This document presents a new filtering method and converter transformer design for HVDC systems. The new design aims to address issues with traditional converter transformers and passive filtering methods, such as additional harmonic losses and difficulties meeting insulation requirements.
The new converter transformer uses a prolonged-delta winding configuration and phase shifts of 15 degrees to provide 12-phase commutation voltages. It also employs an inductive filtering mechanism where a tap connects the prolonged and common windings to an LC resonance circuit. This allows harmonic currents to balance out so no inductive harmonics flow in the primary winding.
Simulation results show the new design greatly reduces harmonic content and transformer losses compared to traditional designs. The primary current waveform has lower distortion and THD with the
International Journal of Engineering Research and DevelopmentIJERD Editor
This document summarizes a study investigating two soft-switched isolated DC-DC converter topologies for auxiliary power supply in railways. The converters aim to reduce size and weight by using a lightweight medium frequency transformer instead of heavy 50Hz transformers. One proposed topology uses an auxiliary circuit on the secondary side to achieve zero-current switching for the primary inverter switches. Equations are provided to analyze the operating modes and design considerations of this topology, including resonant component sizing, power device ratings, and output voltage characteristics based on input voltage and load current. Analytical expressions are given to determine maximum stresses on the power devices under different operating conditions.
The document discusses uncontrolled rectifiers, which provide a fixed DC output voltage from an AC supply using diodes. It describes single-phase half-wave and full-wave uncontrolled rectifiers with resistive and resistive-inductive loads. For a half-wave rectifier with resistive load, the average DC output voltage is half the peak AC input voltage. A full-wave rectifier doubles this output voltage by using two pairs of diodes to conduct during both half-cycles of the AC input. Rectifiers with resistive-inductive loads have more complex non-sinusoidal current waveforms that decay during the negative half-cycles.
PWM control techniques for three phase three level inverter drivesTELKOMNIKA JOURNAL
In this paper two very efficient pulse width modulation techniques were discussed named Sin pulse width modulation and space vector pulse width modulation. The basic structure of the three-level inverter neutral-point clamped is introduced and the basic idea about space vector pulse width modulation for three-level voltage source inverter has been discussed in detail. Nearest three vectors space vector pulse width modulation control algorithm is adopted as the control strategy for the three phase three level NPC inverter in order to compensate the neutral-point shifting. Mathematical formulation for calculating switching sequence has determined. Comparative analysis proving superiority of the space vector pulse width modulation technique over the conventional pulse width modulation, and the results of the simulations of inverter confirm the feasibility and advantage of the space vector pulse width modulation strategy over sin pulse width modulation in terms of good utilization of dc-bus voltage, low current ripple and reduced switching frequency. Space vector pulse width modulation provides advantages better fundamental output voltage and useful in improving harmonic performance and reducing total harmonic distortion.
PWM Switched Voltage Source Inverter with Zero Neutral Point Potentialijsrd.com
A three phase three-level pulse width modulation
(PWM) switched voltage source inverter with zero neutral
point potential is designed. It consists of three single-phase
inverter modules and each module is composed of a
switched voltage source and inverter switches. The major
advantage is that the peak value of the phase output voltage
is twice as high as that of the conventional neutral-pointclamped
PWM inverter. Thus, the proposed inverter is
suitable for applications with low voltage sources such as
batteries, fuel cells, or solar cells. Furthermore, three-level
output waveforms of the inverter can be achieved without
the switch voltage unbalance problem. Since the average
neutral point potential of the inverter is zero, a common
ground between the input stage and the output stage is
possible. Therefore, it can be applied to a transformer-less
power conditioning system. The SVS inverter is tested by a
PSIM simulation and hardware is implemented and verified.
The document discusses a fractional frequency transmission system (FFTS) that uses a lower frequency of 50/3 Hz to reduce reactance and increase the transmission capacity of power lines by up to 3 times. It operates by using a cycloconverter to convert the 50/3 Hz electricity to 50 Hz electricity fed into the utility grid. The FFTS approach provides an efficient way to increase long-distance transmission capacity compared to increasing voltage levels or using high-voltage DC transmission. Experimental results show a 1000 km transmission line can transmit more power using FFTS compared to a standard 50 Hz system.
The power electronics device which converts DC power to AC power at required output voltage and frequency level is known as inverter. Multilevel inverter is to synthesize a near sinusoidal voltage from several levels of dc voltages. In order to maintain the different voltage levels at appropriate intervals, the conduction time intervals of MOSFETS have been maintained by controlling the pulse width of gating pulses. In this paper single phase to three phase power conversion using PWM technique. The simulation is carried out in MATLAB/Simulink environment which demonstrate the feasibility of proposed scheme.
To overcome the problem of mismatched voltage levels between parallel-connected low voltage photovoltaic (PV)
arrays and the higher grid voltage, a hybrid boost three level dc-dc converter is developed based on three level inverter with
the traditional single phase diode clamping. Only one inductor, two capacitors in series, and those power switches and diodes,
which are easy to be integrated, are used for establish the topology with transformerless high voltage gain. The operation
principle of the topology is analyzed, and then the pulse width modulation (PWM) control method is obtained according to
the switching functions about the output pulse voltages of both half-bridges. Therefore, the converter can not only operate
with high voltage gain, but also make the duty cycles of power switches closer to 0.5. A feedforward closed loop control
operation is proposed such that even in varying input the converter is capable of giving a constant output. Finally an
experimental is set up in the laboratory for open loop control operation. All experimental results verify the feasibility of the
circuit and validity of the PWM control method.
The document discusses DC to AC conversion using inverters. It describes the basic concept and components of inverters including single-phase, full-bridge, and three-phase inverter topologies. It also covers modulation techniques such as pulse width modulation (PWM) and discusses how they affect the output waveform harmonics.
International Journal of Engineering Research and DevelopmentIJERD Editor
This document summarizes a study investigating two soft-switched isolated DC-DC converter topologies for auxiliary power supply in railways. The converters aim to reduce size and weight by using a lightweight medium frequency transformer instead of heavy 50Hz transformers. One proposed topology uses an auxiliary circuit on the secondary side to achieve zero-current switching for the primary inverter switches. Equations are provided to analyze the operating modes and design considerations of this topology, including resonant component sizing, power device ratings, and output voltage characteristics based on input voltage and load current. Analytical expressions are given to determine maximum stresses on the power devices under different operating conditions.
The document discusses uncontrolled rectifiers, which provide a fixed DC output voltage from an AC supply using diodes. It describes single-phase half-wave and full-wave uncontrolled rectifiers with resistive and resistive-inductive loads. For a half-wave rectifier with resistive load, the average DC output voltage is half the peak AC input voltage. A full-wave rectifier doubles this output voltage by using two pairs of diodes to conduct during both half-cycles of the AC input. Rectifiers with resistive-inductive loads have more complex non-sinusoidal current waveforms that decay during the negative half-cycles.
PWM control techniques for three phase three level inverter drivesTELKOMNIKA JOURNAL
In this paper two very efficient pulse width modulation techniques were discussed named Sin pulse width modulation and space vector pulse width modulation. The basic structure of the three-level inverter neutral-point clamped is introduced and the basic idea about space vector pulse width modulation for three-level voltage source inverter has been discussed in detail. Nearest three vectors space vector pulse width modulation control algorithm is adopted as the control strategy for the three phase three level NPC inverter in order to compensate the neutral-point shifting. Mathematical formulation for calculating switching sequence has determined. Comparative analysis proving superiority of the space vector pulse width modulation technique over the conventional pulse width modulation, and the results of the simulations of inverter confirm the feasibility and advantage of the space vector pulse width modulation strategy over sin pulse width modulation in terms of good utilization of dc-bus voltage, low current ripple and reduced switching frequency. Space vector pulse width modulation provides advantages better fundamental output voltage and useful in improving harmonic performance and reducing total harmonic distortion.
PWM Switched Voltage Source Inverter with Zero Neutral Point Potentialijsrd.com
A three phase three-level pulse width modulation
(PWM) switched voltage source inverter with zero neutral
point potential is designed. It consists of three single-phase
inverter modules and each module is composed of a
switched voltage source and inverter switches. The major
advantage is that the peak value of the phase output voltage
is twice as high as that of the conventional neutral-pointclamped
PWM inverter. Thus, the proposed inverter is
suitable for applications with low voltage sources such as
batteries, fuel cells, or solar cells. Furthermore, three-level
output waveforms of the inverter can be achieved without
the switch voltage unbalance problem. Since the average
neutral point potential of the inverter is zero, a common
ground between the input stage and the output stage is
possible. Therefore, it can be applied to a transformer-less
power conditioning system. The SVS inverter is tested by a
PSIM simulation and hardware is implemented and verified.
The document discusses a fractional frequency transmission system (FFTS) that uses a lower frequency of 50/3 Hz to reduce reactance and increase the transmission capacity of power lines by up to 3 times. It operates by using a cycloconverter to convert the 50/3 Hz electricity to 50 Hz electricity fed into the utility grid. The FFTS approach provides an efficient way to increase long-distance transmission capacity compared to increasing voltage levels or using high-voltage DC transmission. Experimental results show a 1000 km transmission line can transmit more power using FFTS compared to a standard 50 Hz system.
The power electronics device which converts DC power to AC power at required output voltage and frequency level is known as inverter. Multilevel inverter is to synthesize a near sinusoidal voltage from several levels of dc voltages. In order to maintain the different voltage levels at appropriate intervals, the conduction time intervals of MOSFETS have been maintained by controlling the pulse width of gating pulses. In this paper single phase to three phase power conversion using PWM technique. The simulation is carried out in MATLAB/Simulink environment which demonstrate the feasibility of proposed scheme.
To overcome the problem of mismatched voltage levels between parallel-connected low voltage photovoltaic (PV)
arrays and the higher grid voltage, a hybrid boost three level dc-dc converter is developed based on three level inverter with
the traditional single phase diode clamping. Only one inductor, two capacitors in series, and those power switches and diodes,
which are easy to be integrated, are used for establish the topology with transformerless high voltage gain. The operation
principle of the topology is analyzed, and then the pulse width modulation (PWM) control method is obtained according to
the switching functions about the output pulse voltages of both half-bridges. Therefore, the converter can not only operate
with high voltage gain, but also make the duty cycles of power switches closer to 0.5. A feedforward closed loop control
operation is proposed such that even in varying input the converter is capable of giving a constant output. Finally an
experimental is set up in the laboratory for open loop control operation. All experimental results verify the feasibility of the
circuit and validity of the PWM control method.
The document discusses DC to AC conversion using inverters. It describes the basic concept and components of inverters including single-phase, full-bridge, and three-phase inverter topologies. It also covers modulation techniques such as pulse width modulation (PWM) and discusses how they affect the output waveform harmonics.
This document provides an overview of forward-type switched mode power supplies (SMPS). It begins by stating the objectives and introducing the basic topology, which consists of a switching device, transformer, and rectification/filtering circuit. It then explains the principles of operation, including two modes - the powering mode when the switch is on, and the freewheeling mode when it is off. Key points covered include the relationship between input/output voltages and duty cycle, and factors that influence the sizing of filter components like the switching frequency. Practical considerations like non-ideal transformer characteristics necessitate modifications to the basic circuit.
Control of HVDC Transmission System Based on MMC with Three-Level Flying Capa...Anand Parakkat Parambil
The document contains a list of figures for chapters 3-5 of a thesis on controlling an HVDC transmission system based on modular multilevel converters (MMC) with three-level flying capacitor submodules. Chapter 3 describes the system and modeling of the MMC, including the topology and operation of the converter. Chapter 4 discusses the control and modulation of the MMC-HVDC system, including AC and DC current control loops for the two MMC stations and arm balancing control. Chapter 5 presents simulation results evaluating the system.
Application of SVM Technique for Three Phase Three Leg Ac/Ac Converter TopologyIOSR Journals
This paper presents a simulation of a three-phase three-leg AC/AC converter topology using nine IGBTs and space vector pulse width modulation (SVM) technique. The proposed topology reduces the number of switches compared to conventional back-to-back and matrix converters. Simulation results show the converter provides sinusoidal input and output voltages with unity power factor under constant frequency and variable frequency operation. Experimental results from a 5kVA prototype verify the validity of the proposed scheme.
Multi Pulse Rectifier Using Different Phase Shifting Transformers and its THD...IRJET Journal
This document discusses multi-pulse rectifiers and their use in reducing harmonics compared to a standard six-pulse rectifier. It describes how multi-pulse rectifiers use different transformer configurations like star-delta, delta-star, and zig-zag connections to provide phase shifting and produce more than six pulses of DC voltage per cycle. This reduces the total harmonic distortion in the input current. The document analyzes rectifiers with 6, 12, 18, 24 and 36 pulses and their relative THD levels. Higher pulse rectifiers provide better power quality but require more complex transformer designs.
IRJET- Simulation of Energization and De-Energization of Capacitor Banks and ...IRJET Journal
This document discusses simulation of transient overvoltages caused by energization and de-energization of capacitor banks in distribution systems. The key points are:
1. Energization of capacitor banks causes larger transient overvoltage peaks compared to de-energization. Peak voltages of 2.48 PU and currents of 2567 A were observed during energization.
2. Different mitigation techniques for transients were simulated, including pre-insertion resistors, inductors, and impedance. Pre-insertion impedance was found to be most effective at reducing transients.
3. Total harmonic distortion of voltages reached 35.34% during energization and 15.34% during de-energization without
Transients Caused by Switching of 420 kV Three-Phase Variable Shunt ReactorBérengère VIGNAUX
This paper describes transients caused by uncontrolled and controlled switching of three-phase 420 kV variable shunt reactor (VSR).
Inrush currents due to VSR energization and overvoltages due to de-energization were determined at tap positions corresponding to lowest 80 MVAr and highest 150 MVAr reactive power. Based on the calculation results, mitigation measures and operating switching strategy of VSR were proposed.
A Single Switch High Gain Coupled Inductor Boost ConverterIRJET Journal
This document summarizes a research paper on a single switch high gain coupled inductor boost converter with closed loop control and low switch voltage stress. The proposed converter uses a coupled inductor and passive clamp network to achieve high voltage gain without high duty cycles. This prevents problems like reverse recovery and reduces switch voltage stress. Simulation results show the converter operates with a 40V input and 400V/400W output at 50kHz switching frequency using optimized component values determined through design calculations.
This document analyzes a transistor clamped H-bridge split phase PWM inverter. It presents the circuit diagram of the proposed inverter which uses coupled inductors to prevent short circuits and reduce reverse recovery losses. A double reference single carrier modulation technique is used to generate PWM signals from two reference signals and a triangular carrier, producing a five-level output voltage. Simulation results in MATLAB Simulink show the five-level output voltage waveform and total harmonic distortion of 8.43%, demonstrating reduced harmonics compared to conventional inverters. The proposed inverter topology and modulation control method aim to improve efficiency, reliability and output waveform quality.
Iaetsd analysis of zvs, zcs interleaved boost - converterwith ac driveIaetsd Iaetsd
The document analyzes an interleaved boost converter with zero-voltage switching and zero-current switching for improved efficiency. An interleaved boost converter uses two or more boost converters operating in parallel to reduce ripple and improve efficiency. The proposed design adds an auxiliary circuit to achieve soft switching, reducing switching losses. It can operate with duty cycles greater than or less than 50% and maintains low voltage stress on the main switches. Analysis of the circuit operation shows it achieves zero-voltage turn-on and zero-current turn-off of the main switches through resonant charging and discharging of parasitic capacitances during the switching transitions. Simulations and experimental results demonstrate improved efficiency over 90% across a range of loads.
This document discusses Matlab/Simulink implementation for reducing motor derating and torque pulsation of an induction motor using a matrix converter. It provides background on how non-sinusoidal supply from traditional inverters causes harmonic losses and torque pulsation in induction motors. The document summarizes simulation results showing that a matrix converter can provide a pure sinusoidal supply, reducing harmonic losses and torque pulsation. Simulations of a matrix converter driving an induction motor in Matlab/Simulink are presented, showing sinusoidal voltage/current waveforms and reduced torque pulsation at steady state.
International Journal of Engineering Research and DevelopmentIJERD Editor
This document describes a novel bidirectional DC-DC converter that can provide high step-up and step-down voltage gains. It utilizes a coupled inductor with the same number of turns in the primary and secondary windings to achieve these high voltage gains. The steady-state analysis and operating principles of the converter in continuous conduction mode are presented. Simulations in MATLAB are used to verify the performance of the proposed converter and show it can provide constant output voltage when feedback is applied. Compared to a conventional bidirectional DC-DC converter, the proposed design offers higher voltage conversion ratios in both step-up and step-down modes of operation.
The document summarizes a proposed non-isolated ZVZCS resonant PWM converter for high step-up and high power applications. The proposed converter uses an interleaved structure of basic cells connected in series and parallel to achieve flexibility in device selection. It allows soft-switching turn-on of switches via zero-voltage switching and turn-off of diodes via zero-current switching through the use of an auxiliary circuit. Simulation results are provided to validate the converter's operation and advantages over conventional hard-switched converters, such as reduced switch voltage and current stresses leading to higher efficiency.
SIMULATION ANALYSIS OF CLOSED LOOP DUAL INDUCTOR CURRENT-FED PUSH-PULL CONVER...Journal For Research
The current electronic devices require DC power source, which is taken from a battery or DC power supply. DC-DC converter is utilized to get regulated dc voltage from unregulated one. Switched mode power supply (SMPS) are commonly used in industrial applications, because of more advantages compared to linear power supply. In SMPS we have isolated and non-isolated converters, where isolated converters are frequently used, in order to get more voltage with multiple outputs. So among different isolated converters, push-pull converter is chosen for micro converter applications to obtain high voltage conversion ratio by using HF transformer, due to their better utilization of transformer. New methodology of control is implemented for making ZVS and ZCS at same time and to reduce the number of switches in the secondary side of dual inductor CFPP converter, which is a voltage doubler circuit. This becomes the solution for problem identification. Thus this converter with soft-switching reduces the switching losses.The current-fed push-pull converters are used in many applications like photo-voltaic (PV) power converters for boosting the output voltage. Push-pull converter is chosen for micro converter applications, to obtain high voltage conversion ratio by using high frequency (HF) transformer, due to their better utilization of transformer. This deals with the design of dual inductor CFPP converter, where zero voltage switching (ZVS) and zero current switching (ZCS) is achieved for the primary side of the converter by using secondary switches. Primary side switches are controlled by closed loop control topology. The secondary side is made with voltage doubler to obtain high voltage. Open loop and closed loop control of dual inductor current fed push pull converter simulation is finished by MATLAB/SIMULINK and their outcomes are analyzed.
2 twofold mode series echoing dc dc converter for ample loadchelliah paramasivan
The document describes a dual-mode full-bridge series resonant DC-DC converter that can operate at either a variable switching frequency or a fixed switching frequency with phase-shifted pulse width modulation to regulate the output voltage over a wide range of loads. The converter uses a series resonant tank consisting of an inductor and capacitor to achieve soft switching and zero voltage switching of the transistors. It can operate in a frequency modulation mode at high loads by varying the switching frequency, or in a phase modulation mode at light loads using a fixed high switching frequency and varying the duty cycle through phase-shifted pulse width modulation. This dual-mode operation provides high conversion efficiency across a wide range of loads.
Modeling and Simulation of a Carrier-based PWM Voltage Source Inverter for a ...IAES-IJPEDS
The analysis of a carrier-based PWM two level voltage source inverter for a nine phase induction machine drive system is presented in this paper. Methods for generating zero-sequence signals during balanced and unbalanced condition are established. Simulation results for the analysis are presented. Two fault conditions involving the voltage source inverter and the nine-phase squirrel cage induction machine load are investigated. For the two fault scenarios considered, the effects on the performance characteristics of the induction machine load are highlighted. The simulation results obtained show that the two imbalance conditions considered result in substantial oscillations on the electromagnetic torque of the machine with attendant reduction in the torque rating. There is also large slip in the rotor speed.
This document contains 5 problems related to transmission lines and circuits. Problem 1 asks to calculate the ABCD parameters of a transmission line system including transformers. Problem 2 gives the ABCD parameters and asks for the sending end voltage, current, and power factor. Problem 3 asks for the sending end voltage given two lines in parallel. Problem 4 asks for the ABCD parameters and characteristic impedance of a pi network transmission line. Problem 5 asks for the resistances of an equivalent T-network model of a two-port resistive circuit.
This document describes a simulation of a space vector PWM controller for a five-level voltage-fed inverter motor drive. It begins by introducing multilevel inverters and some of the challenges in controlling them, specifically the increased complexity with more levels. It then presents a new approach to implementing space vector PWM for a five-level inverter by treating it as a conventional two-level system, making the calculations simpler. The methodology and implementation are described, including estimating switching times. Simulation results are presented showing the current, voltage and THD waveforms both with and without an LC filter. It is concluded that the proposed 2D system approach allows for simple implementation of SVPWM for a five-level inverter using common D
H6 Transformer less Topology and Its Modulation Strategy for Mitigating Cm Cu...IJERA Editor
MATLABbasedsingle-phase three-level topology for a transformer less photovoltaic system is presented in this paper. Compared with the conventional H-bridge topology, it only needs two additional asymmetrically distributed switches, and the system common-mode voltage can be kept constant with a simple modulation scheme. Family of H6 transformer less inverter topologies with low leakage currents is proposed and highly efficient and reliable inverter concept (HERIC) topology is also presented in this paper. The proposed inverter can also operate with high frequency by retaining high efficiency which enables reduced cooling system. Finally, the proposed new topology is simulated by MATLAB/Simulink software to validate the accuracy of the theoretical explanation.
A Hierarchical Feature Set optimization for effective code change based Defec...IOSR Journals
This document summarizes research on using support vector machines (SVMs) for software defect prediction. It analyzes 11 datasets from NASA projects containing code metrics and defect information for modules. The researchers preprocessed the data by removing duplicate/inconsistent instances, constant attributes, and balancing the datasets. They used SVMs with 5-fold cross validation to classify modules as defective or non-defective, achieving an average accuracy of 70% across the datasets. The researchers conclude SVMs can effectively predict defects but note earlier studies using the NASA data may have overstated capabilities due to insufficient data preprocessing.
The document provides an overview of steganography, including:
1) Steganography is the technique of hiding secret information within a cover file such that the existence of the secret information is concealed. It aims for invisible communication.
2) The main components of a steganographic system are the secret message, cover file, stego file, key, embedding and extracting methods.
3) Steganography differs from cryptography in that it does not alter the structure of the secret message and aims to conceal the very existence of communication, whereas cryptography scrambles messages and is known to transmit encrypted messages.
This document provides an overview of forward-type switched mode power supplies (SMPS). It begins by stating the objectives and introducing the basic topology, which consists of a switching device, transformer, and rectification/filtering circuit. It then explains the principles of operation, including two modes - the powering mode when the switch is on, and the freewheeling mode when it is off. Key points covered include the relationship between input/output voltages and duty cycle, and factors that influence the sizing of filter components like the switching frequency. Practical considerations like non-ideal transformer characteristics necessitate modifications to the basic circuit.
Control of HVDC Transmission System Based on MMC with Three-Level Flying Capa...Anand Parakkat Parambil
The document contains a list of figures for chapters 3-5 of a thesis on controlling an HVDC transmission system based on modular multilevel converters (MMC) with three-level flying capacitor submodules. Chapter 3 describes the system and modeling of the MMC, including the topology and operation of the converter. Chapter 4 discusses the control and modulation of the MMC-HVDC system, including AC and DC current control loops for the two MMC stations and arm balancing control. Chapter 5 presents simulation results evaluating the system.
Application of SVM Technique for Three Phase Three Leg Ac/Ac Converter TopologyIOSR Journals
This paper presents a simulation of a three-phase three-leg AC/AC converter topology using nine IGBTs and space vector pulse width modulation (SVM) technique. The proposed topology reduces the number of switches compared to conventional back-to-back and matrix converters. Simulation results show the converter provides sinusoidal input and output voltages with unity power factor under constant frequency and variable frequency operation. Experimental results from a 5kVA prototype verify the validity of the proposed scheme.
Multi Pulse Rectifier Using Different Phase Shifting Transformers and its THD...IRJET Journal
This document discusses multi-pulse rectifiers and their use in reducing harmonics compared to a standard six-pulse rectifier. It describes how multi-pulse rectifiers use different transformer configurations like star-delta, delta-star, and zig-zag connections to provide phase shifting and produce more than six pulses of DC voltage per cycle. This reduces the total harmonic distortion in the input current. The document analyzes rectifiers with 6, 12, 18, 24 and 36 pulses and their relative THD levels. Higher pulse rectifiers provide better power quality but require more complex transformer designs.
IRJET- Simulation of Energization and De-Energization of Capacitor Banks and ...IRJET Journal
This document discusses simulation of transient overvoltages caused by energization and de-energization of capacitor banks in distribution systems. The key points are:
1. Energization of capacitor banks causes larger transient overvoltage peaks compared to de-energization. Peak voltages of 2.48 PU and currents of 2567 A were observed during energization.
2. Different mitigation techniques for transients were simulated, including pre-insertion resistors, inductors, and impedance. Pre-insertion impedance was found to be most effective at reducing transients.
3. Total harmonic distortion of voltages reached 35.34% during energization and 15.34% during de-energization without
Transients Caused by Switching of 420 kV Three-Phase Variable Shunt ReactorBérengère VIGNAUX
This paper describes transients caused by uncontrolled and controlled switching of three-phase 420 kV variable shunt reactor (VSR).
Inrush currents due to VSR energization and overvoltages due to de-energization were determined at tap positions corresponding to lowest 80 MVAr and highest 150 MVAr reactive power. Based on the calculation results, mitigation measures and operating switching strategy of VSR were proposed.
A Single Switch High Gain Coupled Inductor Boost ConverterIRJET Journal
This document summarizes a research paper on a single switch high gain coupled inductor boost converter with closed loop control and low switch voltage stress. The proposed converter uses a coupled inductor and passive clamp network to achieve high voltage gain without high duty cycles. This prevents problems like reverse recovery and reduces switch voltage stress. Simulation results show the converter operates with a 40V input and 400V/400W output at 50kHz switching frequency using optimized component values determined through design calculations.
This document analyzes a transistor clamped H-bridge split phase PWM inverter. It presents the circuit diagram of the proposed inverter which uses coupled inductors to prevent short circuits and reduce reverse recovery losses. A double reference single carrier modulation technique is used to generate PWM signals from two reference signals and a triangular carrier, producing a five-level output voltage. Simulation results in MATLAB Simulink show the five-level output voltage waveform and total harmonic distortion of 8.43%, demonstrating reduced harmonics compared to conventional inverters. The proposed inverter topology and modulation control method aim to improve efficiency, reliability and output waveform quality.
Iaetsd analysis of zvs, zcs interleaved boost - converterwith ac driveIaetsd Iaetsd
The document analyzes an interleaved boost converter with zero-voltage switching and zero-current switching for improved efficiency. An interleaved boost converter uses two or more boost converters operating in parallel to reduce ripple and improve efficiency. The proposed design adds an auxiliary circuit to achieve soft switching, reducing switching losses. It can operate with duty cycles greater than or less than 50% and maintains low voltage stress on the main switches. Analysis of the circuit operation shows it achieves zero-voltage turn-on and zero-current turn-off of the main switches through resonant charging and discharging of parasitic capacitances during the switching transitions. Simulations and experimental results demonstrate improved efficiency over 90% across a range of loads.
This document discusses Matlab/Simulink implementation for reducing motor derating and torque pulsation of an induction motor using a matrix converter. It provides background on how non-sinusoidal supply from traditional inverters causes harmonic losses and torque pulsation in induction motors. The document summarizes simulation results showing that a matrix converter can provide a pure sinusoidal supply, reducing harmonic losses and torque pulsation. Simulations of a matrix converter driving an induction motor in Matlab/Simulink are presented, showing sinusoidal voltage/current waveforms and reduced torque pulsation at steady state.
International Journal of Engineering Research and DevelopmentIJERD Editor
This document describes a novel bidirectional DC-DC converter that can provide high step-up and step-down voltage gains. It utilizes a coupled inductor with the same number of turns in the primary and secondary windings to achieve these high voltage gains. The steady-state analysis and operating principles of the converter in continuous conduction mode are presented. Simulations in MATLAB are used to verify the performance of the proposed converter and show it can provide constant output voltage when feedback is applied. Compared to a conventional bidirectional DC-DC converter, the proposed design offers higher voltage conversion ratios in both step-up and step-down modes of operation.
The document summarizes a proposed non-isolated ZVZCS resonant PWM converter for high step-up and high power applications. The proposed converter uses an interleaved structure of basic cells connected in series and parallel to achieve flexibility in device selection. It allows soft-switching turn-on of switches via zero-voltage switching and turn-off of diodes via zero-current switching through the use of an auxiliary circuit. Simulation results are provided to validate the converter's operation and advantages over conventional hard-switched converters, such as reduced switch voltage and current stresses leading to higher efficiency.
SIMULATION ANALYSIS OF CLOSED LOOP DUAL INDUCTOR CURRENT-FED PUSH-PULL CONVER...Journal For Research
The current electronic devices require DC power source, which is taken from a battery or DC power supply. DC-DC converter is utilized to get regulated dc voltage from unregulated one. Switched mode power supply (SMPS) are commonly used in industrial applications, because of more advantages compared to linear power supply. In SMPS we have isolated and non-isolated converters, where isolated converters are frequently used, in order to get more voltage with multiple outputs. So among different isolated converters, push-pull converter is chosen for micro converter applications to obtain high voltage conversion ratio by using HF transformer, due to their better utilization of transformer. New methodology of control is implemented for making ZVS and ZCS at same time and to reduce the number of switches in the secondary side of dual inductor CFPP converter, which is a voltage doubler circuit. This becomes the solution for problem identification. Thus this converter with soft-switching reduces the switching losses.The current-fed push-pull converters are used in many applications like photo-voltaic (PV) power converters for boosting the output voltage. Push-pull converter is chosen for micro converter applications, to obtain high voltage conversion ratio by using high frequency (HF) transformer, due to their better utilization of transformer. This deals with the design of dual inductor CFPP converter, where zero voltage switching (ZVS) and zero current switching (ZCS) is achieved for the primary side of the converter by using secondary switches. Primary side switches are controlled by closed loop control topology. The secondary side is made with voltage doubler to obtain high voltage. Open loop and closed loop control of dual inductor current fed push pull converter simulation is finished by MATLAB/SIMULINK and their outcomes are analyzed.
2 twofold mode series echoing dc dc converter for ample loadchelliah paramasivan
The document describes a dual-mode full-bridge series resonant DC-DC converter that can operate at either a variable switching frequency or a fixed switching frequency with phase-shifted pulse width modulation to regulate the output voltage over a wide range of loads. The converter uses a series resonant tank consisting of an inductor and capacitor to achieve soft switching and zero voltage switching of the transistors. It can operate in a frequency modulation mode at high loads by varying the switching frequency, or in a phase modulation mode at light loads using a fixed high switching frequency and varying the duty cycle through phase-shifted pulse width modulation. This dual-mode operation provides high conversion efficiency across a wide range of loads.
Modeling and Simulation of a Carrier-based PWM Voltage Source Inverter for a ...IAES-IJPEDS
The analysis of a carrier-based PWM two level voltage source inverter for a nine phase induction machine drive system is presented in this paper. Methods for generating zero-sequence signals during balanced and unbalanced condition are established. Simulation results for the analysis are presented. Two fault conditions involving the voltage source inverter and the nine-phase squirrel cage induction machine load are investigated. For the two fault scenarios considered, the effects on the performance characteristics of the induction machine load are highlighted. The simulation results obtained show that the two imbalance conditions considered result in substantial oscillations on the electromagnetic torque of the machine with attendant reduction in the torque rating. There is also large slip in the rotor speed.
This document contains 5 problems related to transmission lines and circuits. Problem 1 asks to calculate the ABCD parameters of a transmission line system including transformers. Problem 2 gives the ABCD parameters and asks for the sending end voltage, current, and power factor. Problem 3 asks for the sending end voltage given two lines in parallel. Problem 4 asks for the ABCD parameters and characteristic impedance of a pi network transmission line. Problem 5 asks for the resistances of an equivalent T-network model of a two-port resistive circuit.
This document describes a simulation of a space vector PWM controller for a five-level voltage-fed inverter motor drive. It begins by introducing multilevel inverters and some of the challenges in controlling them, specifically the increased complexity with more levels. It then presents a new approach to implementing space vector PWM for a five-level inverter by treating it as a conventional two-level system, making the calculations simpler. The methodology and implementation are described, including estimating switching times. Simulation results are presented showing the current, voltage and THD waveforms both with and without an LC filter. It is concluded that the proposed 2D system approach allows for simple implementation of SVPWM for a five-level inverter using common D
H6 Transformer less Topology and Its Modulation Strategy for Mitigating Cm Cu...IJERA Editor
MATLABbasedsingle-phase three-level topology for a transformer less photovoltaic system is presented in this paper. Compared with the conventional H-bridge topology, it only needs two additional asymmetrically distributed switches, and the system common-mode voltage can be kept constant with a simple modulation scheme. Family of H6 transformer less inverter topologies with low leakage currents is proposed and highly efficient and reliable inverter concept (HERIC) topology is also presented in this paper. The proposed inverter can also operate with high frequency by retaining high efficiency which enables reduced cooling system. Finally, the proposed new topology is simulated by MATLAB/Simulink software to validate the accuracy of the theoretical explanation.
A Hierarchical Feature Set optimization for effective code change based Defec...IOSR Journals
This document summarizes research on using support vector machines (SVMs) for software defect prediction. It analyzes 11 datasets from NASA projects containing code metrics and defect information for modules. The researchers preprocessed the data by removing duplicate/inconsistent instances, constant attributes, and balancing the datasets. They used SVMs with 5-fold cross validation to classify modules as defective or non-defective, achieving an average accuracy of 70% across the datasets. The researchers conclude SVMs can effectively predict defects but note earlier studies using the NASA data may have overstated capabilities due to insufficient data preprocessing.
The document provides an overview of steganography, including:
1) Steganography is the technique of hiding secret information within a cover file such that the existence of the secret information is concealed. It aims for invisible communication.
2) The main components of a steganographic system are the secret message, cover file, stego file, key, embedding and extracting methods.
3) Steganography differs from cryptography in that it does not alter the structure of the secret message and aims to conceal the very existence of communication, whereas cryptography scrambles messages and is known to transmit encrypted messages.
Some Aspects of Stress Distribution and Effect of Voids Having Different Gase...IOSR Journals
1) The document analyzes the stress distribution and effect of voids with different gases in MV power cables through finite element modeling. It studies the electric field and temperature distribution within cable insulation containing voids.
2) Cylindrical voids are found to have higher electric stress than spherical or elliptical voids. Among gases, oxygen consumption during partial discharge causes greater temperature rise and faster breakdown than nitrogen.
3) The analysis examines factors like void shape, position, and size that influence stress distribution and partial discharge inception voltage. Nearer and larger voids have lower inception voltages. Oxygen consumption leads to uniform erosion and higher temperatures, making its effect greater than other gases.
This document presents the results of an XRF analysis of 23 bentonite samples collected from different parts of Jharkhand, India. The analysis was conducted to determine the chemical composition and theoretical molecular formula of the samples. Key findings include:
- The chemical composition of most samples is comparable to bentonite from Rajmahal hills and literature values, indicating good quality bentonite.
- Composition varied across samples but most were high in silica (50.93-59.87%) and had silica to alumina ratios consistent with bentonite.
- One sample had an unusually low alumina content and high silica to alumina ratio, suggesting poorer quality.
- The theoretical molecular formulas derived were consistent with
An Optimal Approach to derive Disjunctive Positive and Negative Rules from As...IOSR Journals
This document discusses an optimal approach to derive disjunctive positive and negative association rules from association rule mining using a genetic algorithm. It aims to address some shortfalls of conventional algorithms like Apriori by supporting disjunctive rules, using multiple minimum support thresholds, and effectively identifying negative rules. The proposed approach uses a modified FP-Growth algorithm and genetic algorithm to generate conjunctive and disjunctive positive and negative rules in an optimized manner by reducing candidate generation time and capturing useful rare item relationships.
Adjustment of Cost 231 Hata Path Model For Cellular Transmission in Rivers StateIOSR Journals
The document presents an adjustment of the COST 231 Hata path loss model for predicting radio signal propagation in Rivers State, Nigeria. Field measurements of received signal strength were taken in urban, suburban, and rural areas and compared to the COST 231 Hata model, Stanford University Interim model, and ECC-33 model. The COST 231 Hata model gave better predictions but with high error values outside acceptable ranges. The COST 231 Hata model was then adjusted using a linear least squares algorithm based on the field measurements. The adjusted COST 231 Hata model provided better predictions with minimum error within acceptable values and can accurately predict radio characteristics in Rivers State.
The document discusses compressive wideband power spectrum analysis for EEG signals using FastICA and neural networks. It first provides background on EEG signals and how they are measured. It then describes using FastICA to extract independent components from EEG signals related to detecting epileptic seizures. The independent components are then used to train a backpropagation neural network for effective detection of epileptic seizures. The proposed method involves preprocessing EEG signals, performing spectral estimation using FastICA, and classifying brain activity patterns using the neural network.
This document summarizes the results of chemical analysis of two types of freshwater macroalgae, Chara sp. and Spirogyra, collected from Bestansur Village in Iraq. High performance liquid chromatography (HPLC) was used to identify and quantify various chemical constituents. HPLC analysis found that both algae contained alkaloids like kaempfertin, isoquinoline, corilagin and colocynthitin. Spirogyra also contained gallic acid. Both algae contained five steroid compounds and Chara sp. was found to contain high levels of tocopherols like alpha-tocopherol. Inductively coupled plasma analysis also identified various elements in the algae
This document describes the development and validation of a stability-indicating high-performance thin layer chromatography (HPTLC) method for the analysis of modafinil, both as a bulk drug and in tablet formulations. The method utilizes silica gel plates with an ethyl acetate, acetone and methanol mobile phase. Modafinil demonstrates good linearity, precision, accuracy and robustness within the method validation parameters. The method is also shown to distinguish modafinil from its degradation products formed under various stress conditions like acid and base hydrolysis, oxidation, photolysis and heat. The developed HPTLC method can be applied for the quantitative analysis and identification of modafinil in pharmaceutical formulations.
Portfolio Cost Management in Offshore Software Development Outsourcing Relat...IOSR Journals
This document discusses portfolio cost management in offshore software development outsourcing relationships from the vendor's perspective. It aims to identify critical success factors and barriers through a systematic literature review. The objective is to gain an in-depth understanding of portfolio cost management in the context of client-vendor relationships. Portfolio management is important for vendors, especially small vendors, to balance multiple outsourced projects. Effective portfolio cost management can help optimize resource allocation and maximize financial returns. The expected outcomes are identifying key success factors and barriers that influence portfolio cost management in outsourcing relationships.
Performance Evaluation of Routing Protocols for MAC Layer ModelsIOSR Journals
This document evaluates the performance of several routing protocols (Bellman-Ford, AODV, DSR, LAR1, WRP, FSR, ZRP) for different MAC layer models (802.11, CSMA, TSMA) using the GloMoSim simulator. Key metrics analyzed are packet delivery ratio, end-to-end delay, and throughput. The results show that for 802.11, AODV and LAR1 have the highest packet delivery ratios and throughput, while WRP and FSR have the lowest delays. For CSMA and TSMA, ZRP demonstrates the best overall performance due to its ability to use both proactive and reactive routing.
Detecting the High Level Similarities in Software Implementation Process Usin...IOSR Journals
1) The document discusses detecting higher-level structural clones in software, beyond just simple code clones. Structural clones show larger patterns of similarity than simple clones alone.
2) It proposes a technique called Clone Miner to detect structural clones using data mining. Clone Miner formulates the structural clone concept and applies data mining to detect these similarities.
3) Detecting structural clones can help with tasks like software maintenance, reengineering for reuse, and understanding the overall design of a system.
Implementation of FC-TCR for Reactive Power ControlIOSR Journals
This document discusses the implementation of a Fixed Capacitor Thyristor Controlled Reactor (FC-TCR) system for reactive power control. FC-TCR is a type of Static VAR Compensator (SVC) that can inject or absorb reactive power to control voltage. It consists of a fixed capacitor in parallel with a thyristor controlled reactor. The reactor current is controlled by varying the firing angle of thyristors, allowing both lagging and leading reactive power. MATLAB simulation results show that reactive power output from the FC-TCR increases as the reactor inductance increases while keeping the capacitor constant, demonstrating effective reactive power control.
This document describes a column decoder design for memory that aims to minimize power and area. It summarizes the key components of a memory architecture including a 6-transistor memory cell, precharge circuit, sense amplifier, row decoder, column decoder, and control logic. The column decoder is implemented using pass transistor logic to reduce the number of transistors and area. Simulation results show the output waveforms of the column decoder, bidirectional multiplexer, sense amplifier, and control signals, verifying the read and write cycles. The design aims to reduce memory area by using a more efficient multiplexer and reducing the required number of sense amplifiers.
Environmental health Effect and Air Pollution from cigarette smokers in Cross...IOSR Journals
The document examines the environmental health effects and air pollution from cigarette smokers in Cross River State, Nigeria. It analyzes data collected through questionnaires distributed to over 87,000 men across the state's 18 local government areas. The results show high levels of smoking, with the average number of cigarettes consumed per person per day ranging from 12 to 30. Over 900 patients were found to have smoking-related diseases like lung cancer, heart attacks, and respiratory illnesses. The study concludes that air pollution from cigarette smoking is a major contributor to health issues in Cross River State.
Open Source Software Survivability Analysis Using Communication Pattern Valid...IOSR Journals
This document proposes a communication validation tool to analyze the communication patterns of open source software developer communities. The tool would calculate metrics like contribution index, community betweenness centrality, and community density for the Apache Qpid open source project. It outlines formulas to measure these metrics from data extracted from emails between developers, such as number of messages sent and received. The metrics are intended to provide insight into developer contributions, the flow of information between developers, and the cohesiveness of the community over time.
Influence of Different Soil Management Practices On Soil Properties and Its I...IOSR Journals
This document summarizes a study on the influence of different land management practices (forest land, golf course, continuous cropping) on soil properties in southeastern Nigeria. Soil samples were collected from the different land use systems and analyzed. Results showed higher levels of exchangeable bases, organic matter, total nitrogen, and available phosphorus in the top 0-20cm soil layer compared to deeper layers, and forest land generally had higher values than the other land uses. Bulk density decreased and total porosity increased with continuous cropping compared to forest land and golf course. Overall, continuous cultivation was found to deplete soil nutrients and reduce soil productivity more than the other land management practices studied.
Efficient Fpe Algorithm For Encrypting Credit Card NumbersIOSR Journals
This document proposes an efficient format-preserving encryption (FPE) algorithm for encrypting credit card numbers. The algorithm uses AES-128 encryption and adds two additional steps to retain the plaintext format of 16 decimal digits. Specifically, it divides the 128-bit ciphertext into blocks, performs an XOR operation between blocks, and then converts the resulting hexadecimal values to decimal digits. This allows encryption without changing the database structure or queries. The proposed algorithm is faster and requires no additional storage compared to existing FPE techniques like prefix encryption, cycle walking, or Feistel networks. It provides an efficient way to encrypt sensitive numeric fields like credit cards while preserving functionality.
Improved Fuzzy Control Strategy for Power Quality in Distributed Generation’s...IOSR Journals
This document describes an improved fuzzy control strategy for a single-phase inverter used in distributed power generation systems to improve power quality. The control strategy allows the inverter to generate active power from a renewable energy source while also compensating for reactive power and current harmonics from local nonlinear loads. The control scheme uses a reference current generator based on sinusoidal signal integrators and instantaneous reactive power theory. It also employs a dedicated repetitive current controller with a fuzzy controller. Simulation results demonstrate the feasibility of the proposed solution for active power generation, reactive power compensation, and harmonic compensation when connected to the grid.
A Survey on Network Layer Multicast Routing Protocols for Mobile Ad Hoc Netw...IOSR Journals
This document summarizes a survey on network layer multicast routing protocols for mobile ad hoc networks. It begins with an introduction to multicast routing in MANETs and their advantages over unicast. It then provides an overview of the architecture for multicast routing protocols, which consists of three layers: the MAC, routing, and application layers. The document classifies and discusses issues with designing multicast protocols for MANETs. It also categorizes existing multicast routing protocols based on the structure they construct (tree or mesh based), how sessions are initialized (source or receiver initiated), and how topology is maintained (proactively or reactively). Several example protocols are described briefly, including MAODV, AMRIS, and
This document describes an AC-DC matrix converter based on a Cockcroft-Walton voltage multiplier circuit. The converter uses a four bidirectional-switch matrix converter between an AC source and a CW circuit to provide high power factor, adjustable output voltage, and low output ripple. The matrix converter operates at two frequencies - one for power factor correction control and one to set the output frequency. Simulation results show the converter improves efficiency and power factor while reducing output voltage ripple compared to a conventional CW circuit. A 10V AC to 50V DC prototype was built and tested.
Fuzzy Logic Controller Based High Frequency Link AC-AC Converter For Voltage ...IJTET Journal
Abstract—In this paper, an advanced high frequency link AC-AC Push-pull cycloconverter for the voltage compensation is proposed in order to maintain the power quality in electric grid. The proposed methodology can be achieve arbitrary output voltage without using large energy storage elements. So that the system is more steadfast and less costly compared with the conventional inverter topology. Additionally, the proposed converter does not contain any line frequency transformer, which reduces the cost further. The control scheme for the push pull cycloconverter employs the fuzzy logic controller based sinusoidal pulse width modulation (SPWM) to accomplish better performance on voltage compensation, like unbalanced voltage harmonics elimination. The simulation results are given to show the effectiveness of the proposed high frequency link AC-AC converter and fuzzy logic controller based SPWM technology
This document summarizes two possible control techniques for indirectly shaping the input current of a buck power factor correction (PFC) converter by shaping the inductor current. It analyzes the harmonic content of the line current for each control technique to determine the allowable voltage gain (K value) for meeting various harmonic regulations. It then presents a sine-squared modulation control technique that shapes the average inductor current as a sine-squared waveform to indirectly shape the input current in a simplified manner without an averaging circuit. Simulation waveforms and equations are provided to analyze the line current harmonic distortion for different K values using this control technique. Experimental results from a 300W dual interleaved buck PFC converter are also mentioned.
This document presents a simulation study of a novel three-phase AC-AC converter that uses space vector pulse width modulation (SVPWM) at the rectifier and inverter stages. The converter employs unity power factor control to maintain a unity power factor between the input voltage and current. Six cases of simulations were run with varying output voltages, frequencies, and loads. The results show the converter is able to maintain a stable DC link voltage of 1000V while producing sinusoidal output voltages with varying amplitudes and frequencies. The input current is also sinusoidal and in phase with the voltage, demonstrating a unity power factor is achieved across all simulation cases.
International Journal of Engineering Research and DevelopmentIJERD Editor
The document proposes a new multi-string inverter topology for photovoltaic systems connected to the electric grid. It connects multiple PV strings in parallel through diodes before boosting the DC voltage and converting it to AC with an inverter. Simulations show the multi-string topology offers higher efficiency compared to traditional string inverters by reducing losses.
Simulation of H6 full bridge Inverter for grid connected PV system using SPWM...IRJET Journal
This document proposes a new H6 full bridge inverter topology for grid-connected photovoltaic systems using sinusoidal pulse width modulation (SPWM) technique. It aims to reduce common mode leakage currents compared to existing H5 and HERIC inverter topologies. The H6 topology adds two additional switches to the DC side of the full bridge inverter. SPWM pulses for the additional switches are designed to keep the common mode voltage constant during all operating modes, which effectively reduces leakage currents. The MATLAB simulation software is used to simulate the proposed H6 inverter topology and validate the concept.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
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This paper proposed a new sparce matrix converter with Z-source network to provide unity voltage transfer ratio. It is an ac-to-ac converter with diode-IGBT bidirectional switches. The limitations of existing matrix converter like higher current THD and less voltage transfer ratio issues are overcome by this proposed matrix converter by inserting a Z-source. Due to this Z-source current harmonics are totally removed. The simulation is performed for different frequencies. The simulation results are presented to verify the THD and voltage transfer ratio and compared with the existing virtual AC/DC/AC matrix converter. The experimental output voltage amplitude can be varied with the variable frequencies.
A Single-Stage High-Frequency Isolated Secondary- Side Controlled AC-DC Conve...IDES Editor
This paper presents a new single-stage highfrequency
isolated ac-dc converter that uses a simple control
circuit. It is well suitable for wide input variation power
sources. The circuit configuration combines a diode rectifier,
boost converter and half-bridge dc-dc resonant converter. A
high power factor is achieved by discontinuous current mode
(DCM) operation of the front-end integrated power factor
correction circuit. The output voltage is regulated by fixedfrequency,
secondary-side phase-shift active rectifier. Softswitching
operation is achieved for all the switches. This
converter operates in three modes, which is classified
according to conduction of different switches and diodes. The
intervals of operation and steady-state analysis are presented
in detail. Design example of a 100 W proposed converter is
given together with its simulation and experiment results for
wide variation in input voltage.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Modified Bidirectional Converter with Current Fed InverterIJPEDS-IAES
A bidirectional dc-dc converter with multiple outputs are concatenated with a
high frequency current source parallel resonant push pull inverter is
presented in this paper. The two outputs are added together and it is taken as
the input source for the inverter. The current source parallel resonant push
pull inverter implemented here with high frequency applications like
induction heating, Fluorescent lighting, Digital signal processing sonar. This
paper proposes a simple photovoltaic power system consists of a
bidirectional converter and a current fed inverter for regulating the load
variations. Solar power is used as the input source for the system. Simulation
of the proposed system is carried out in PSIM software and experimentally
verified the results.
Efficient Power Factor Correction For Multipulse Bridgeless Active Boost Conv...IRJET Journal
This document presents a modified power factor correction boost converter with a bridgeless active boost converter for a three-phase AC-DC converter system. The proposed design improves upon a conventional 24-pulse rectifier by using a bridgeless topology where the inductor current flows through only two semiconductor devices rather than three. Simulation results show that the proposed bridgeless boost 24-pulse converter improves the power factor from 0.715 to 0.982 compared to the conventional 24-pulse rectifier design.
A New Multilevel Active Power Filter Using Switches Meticulously ControlledIAES-IJPEDS
Shunt active power filter based on multilevel inverter is used to compensate the power factor and to delete the harmonics. This one permits to reduce the inverse voltages applied to the filter switches and their switching frequencies. Nevertheless, the high number of used switches requires a complicated controller and increases the switching losses; where the necessity of finding another resolution system. In this work a new topology of multilevel inverter is proposed as a shunt active power filter using two IGBT transistors in series of opposite sense meticulously controlled by a parallel control algorithm, with the concept of reduced number of six switches which are able to create five levels of the output voltage. This system substute the classical system of eight switches. The harmonic currents identification is carried out using the instantaneous active and reactive power method. The simulation is performed using Matlab/Simulink. The obtained results show that the filtering performances are well enhanced.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
Modeling and Analysis of Transformerless High Gain Buck-boost DC-DC ConvertersIAES-IJPEDS
This paper proposes a transfomerless switched capacitor buck boost converter model, which provides higher voltage gain and higher efficiency when compared to the conventional buck boost converter. The averaged model based on state- space description is analyzed in the paper. The simulation results are presented to confirm the capability of the converter to generate high voltage ratios. The comparison between the proposed model and the traditional model is also provided to reveal the improvement. The proposed converter is suitable for for a wide application which requires high step-up DC-DC converters such as DC micro-grids and solar electrical energy.
International Journal of Engineering Research and DevelopmentIJERD Editor
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Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
This document presents a high efficient loaded resonant converter with feedback for DC-DC energy conversion. The proposed converter consists of a half-bridge inductor-capacitor-inductor resonant inverter connected to a bridge rectifier and load. Soft switching reduces losses and improves efficiency. Simulation results show the converter achieves up to 85.8% efficiency. Feedback control provides accurate output regulation. Analysis and MATLAB simulation demonstrate the converter's improved performance for DC-DC energy conversion applications.
This document provides an overview of EHV AC and DC transmission. It discusses:
1) The construction of EHV AC and DC transmission links, including the components of AC systems and the types of DC links.
2) The limitations and advantages of AC and DC transmission. AC faces challenges with reactive power and stability over long distances, while DC has benefits of lower losses and greater power control.
3) The principal applications of AC and DC transmission, with DC preferred for long distance, asynchronous connections, and submarine cables due to its advantages over AC in these scenarios.
Microcontroller Based Novel Dc-to-Ac Grid Connected Inverter TopologyIDES Editor
The conventional line commutated ac-to-dc
converters/ inverters have square-shaped line current which
contains higher-order harmonics. Moreover, it requires a
costly and bulky dc inductor or choke. The line current with
the high harmonic contents generates EMI and therefore it
causes more heating of the core of distribution or power
transformers. Alternatively, PWM based inverters using
MOSFET/IGBT switches can be used for the above purpose.
However, apart from higher switching losses, the power
handling capability and reliability of these devices are quite
low in comparison to thyristors/ SCR. A thyristor based forced
commutated inverters are not suitable for PWM applications
due to the problems of commutation circuits. A pure sinusoidal
voltage output or waveform with low harmonic contents is
most desirable in the conversion from dc to ac. In the present
work, a novel two pulse line commutated inverter is been
proposed with control signal generated from PIC 16F 877A. It
improves the wave shape hence it reduces the total harmonic
distortion (THD) of the grid interactive-inverter. The
simulation of the circuit is done using SIMULINK. Moreover,
the performance of the proposed circuitry is far better than
the conventional line-commutated inverter. It reduces THD,
number of thyristors and dispenses with the bulky dc inductor/
choke. A prototype model is developed for discontinuous line
current mode. The results are also compared with the
simulation results in SIMULINK/ MATLAB.
This paper introduces a new topology of multilevel inverter, which is able to operate at high performance. This proposed circuit achieves requirements of reduced number of switches, gate-drive circuits, and high design flexibility. In most cases fifteen-level inverters need at least twelve switches. The proposed topology has only ten switches. The inverter has a quasi-sine output voltage, which is formed by level generator and polarity changer to produce the desired voltage and current waveforms. The detailed operation of the proposed inverter is explained. The theoretical analysis and design procedure are given. Simulation results are presented to confirm the analytical approach of the proposed circuit. A 15-level and 31-level multilevel inverters were designed and tested at 50 Hz.
Similar to A New Filtering Method and a Novel Converter Transformer for HVDC System. (20)
This document provides a technical review of secure banking using RSA and AES encryption methodologies. It discusses how RSA and AES are commonly used encryption standards for secure data transmission between ATMs and bank servers. The document first provides background on ATM security measures and risks of attacks. It then reviews related work analyzing encryption techniques. The document proposes using a one-time password in addition to a PIN for ATM authentication. It concludes that implementing encryption standards like RSA and AES can make transactions more secure and build trust in online banking.
This document analyzes the performance of various modulation schemes for achieving energy efficient communication over fading channels in wireless sensor networks. It finds that for long transmission distances, low-order modulations like BPSK are optimal due to their lower SNR requirements. However, as transmission distance decreases, higher-order modulations like 16-QAM and 64-QAM become more optimal since they can transmit more bits per symbol, outweighing their higher SNR needs. Simulations show lifetime extensions up to 550% are possible in short-range networks by using higher-order modulations instead of just BPSK. The optimal modulation depends on transmission distance and balancing the energy used by electronic components versus power amplifiers.
This document provides a review of mobility management techniques in vehicular ad hoc networks (VANETs). It discusses three modes of communication in VANETs: vehicle-to-infrastructure (V2I), vehicle-to-vehicle (V2V), and hybrid vehicle (HV) communication. For each communication mode, different mobility management schemes are required due to their unique characteristics. The document also discusses mobility management challenges in VANETs and outlines some open research issues in improving mobility management for seamless communication in these dynamic networks.
This document provides a review of different techniques for segmenting brain MRI images to detect tumors. It compares the K-means and Fuzzy C-means clustering algorithms. K-means is an exclusive clustering algorithm that groups data points into distinct clusters, while Fuzzy C-means is an overlapping clustering algorithm that allows data points to belong to multiple clusters. The document finds that Fuzzy C-means requires more time for brain tumor detection compared to other methods like hierarchical clustering or K-means. It also reviews related work applying these clustering algorithms to segment brain MRI images.
1) The document simulates and compares the performance of AODV and DSDV routing protocols in a mobile ad hoc network under three conditions: when users are fixed, when users move towards the base station, and when users move away from the base station.
2) The results show that both protocols have higher packet delivery and lower packet loss when users are either fixed or moving towards the base station, since signal strength is better in those scenarios. Performance degrades when users move away from the base station due to weaker signals.
3) AODV generally has better performance than DSDV, with higher throughput and packet delivery rates observed across the different user mobility conditions.
This document describes the design and implementation of 4-bit QPSK and 256-bit QAM modulation techniques using MATLAB. It compares the two techniques based on SNR, BER, and efficiency. The key steps of implementing each technique in MATLAB are outlined, including generating random bits, modulation, adding noise, and measuring BER. Simulation results show scatter plots and eye diagrams of the modulated signals. A table compares the results, showing that 256-bit QAM provides better performance than 4-bit QPSK. The document concludes that QAM modulation is more effective for digital transmission systems.
The document proposes a hybrid technique using Anisotropic Scale Invariant Feature Transform (A-SIFT) and Robust Ensemble Support Vector Machine (RESVM) to accurately identify faces in images. A-SIFT improves upon traditional SIFT by applying anisotropic scaling to extract richer directional keypoints. Keypoints are processed with RESVM and hypothesis testing to increase accuracy above 95% by repeatedly reprocessing images until the threshold is met. The technique was tested on similar and different facial images and achieved better results than SIFT in retrieval time and reduced keypoints.
This document studies the effects of dielectric superstrate thickness on microstrip patch antenna parameters. Three types of probes-fed patch antennas (rectangular, circular, and square) were designed to operate at 2.4 GHz using Arlondiclad 880 substrate. The antennas were tested with and without an Arlondiclad 880 superstrate of varying thicknesses. It was found that adding a superstrate slightly degraded performance by lowering the resonant frequency and increasing return loss and VSWR, while decreasing bandwidth and gain. Specifically, increasing the superstrate thickness or dielectric constant resulted in greater changes to the antenna parameters.
This document describes a wireless environment monitoring system that utilizes soil energy as a sustainable power source for wireless sensors. The system uses a microbial fuel cell to generate electricity from the microbial activity in soil. Two microbial fuel cells were created using different soil types and various additives to produce different current and voltage outputs. An electronic circuit was designed on a printed circuit board with components like a microcontroller and ZigBee transceiver. Sensors for temperature and humidity were connected to the circuit to monitor the environment wirelessly. The system provides a low-cost way to power remote sensors without needing battery replacement and avoids the high costs of wiring a power source.
1) The document proposes a model for a frequency tunable inverted-F antenna that uses ferrite material.
2) The resonant frequency of the antenna can be significantly shifted from 2.41GHz to 3.15GHz, a 31% shift, by increasing the static magnetic field placed on the ferrite material.
3) Altering the permeability of the ferrite allows tuning of the antenna's resonant frequency without changing the physical dimensions, providing flexibility to operate over a wide frequency range.
This document summarizes a research paper that presents a speech enhancement method using stationary wavelet transform. The method first classifies speech into voiced, unvoiced, and silence regions based on short-time energy. It then applies different thresholding techniques to the wavelet coefficients of each region - modified hard thresholding for voiced speech, semi-soft thresholding for unvoiced speech, and setting coefficients to zero for silence. Experimental results using speech from the TIMIT database corrupted with white Gaussian noise at various SNR levels show improved performance over other popular denoising methods.
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A New Filtering Method and a Novel Converter Transformer for HVDC System.
1. IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE)
e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 6, Issue 2 (May. - Jun. 2013), PP 70-76
www.iosrjournals.org
www.iosrjournals.org 70 | Page
A New Filtering Method and a Novel Converter
Transformer for HVDC System.
Mr.A.Hema Sekhar,M.Tech.,(Ph.D), Dr.A.Lakshmi Devi,M.E.,Ph.D
Assosiate Professor & HOD Department. of EEE Sri Venkatesa Perumal college of Engg & Tech,Puttur
Professor ,Dept. of Electrical & Electronics Engineering, Sri Venkateswara University College of
Engineering ,Tirupati
Abstract: A new converter transformer and an inductive filtering method are presented to solve the existing
problems of the traditional converter transformer and the passive filtering method of the high-voltage direct
current (HVDC) system. It adopts the ampere-turn balance of the transformer as the filtering mechanism. A tap
at the linking point of the prolonged winding and the common winding of the secondary windings is connected
with the LC resonance circuit. It can realize the goal that once the harmonic current flows into the prolonged
winding, the common winding will induct the opposite harmonic current to balance it by the zero impedance
design of the common winding and the proper configuration of LC parameters, so there will be no inductive
harmonic current in the primary winding. Moreover, the reactive power that the converter needs can be partly
compensated in the secondary winding. Simulation results have verified the correctness of the theoretical
analysis. The new converter transformer can greatly reduce the harmonic content in the primary winding, loss,
and noise generated by harmonics in the transformer, and the difficulty of the transformer’s insulation design.
Index Terms:Filtering mechanism, harmonic, high-voltage direct current (HVDC), inductive filtering, new
converter transformer
I. Introduction
The high-direct current (HVDC) transmission system has been widely used in remote and large power
transmission, submarine cable transmission, and domain electric network interconnection [1]–[3]. HVDC
transmission system is always made up of a rectifier station, a dc line, and an inverter station. During the
commutating process, a large number of harmonics will be generated by the nonlinear load. Therefore, it is
necessary to carry out harmonic suppression. The traditional HVDC ac passive power filters (PPF) are always
placed at the converter transformer’s primary side (grid side), and the transformer will be adversely affected by
harmonics, which causes a series of problems, such as additional harmonic loss, heat, vibration, and noise [1],
[4]–[7]. In addition, in order to avoid series/parallel resonance between parallel PPF and system impedance, the
traditional PPF cannot reach its tuned point, which greatly affects the filtering effect [8]–[10]. The active
power filter (APF) has better filtering effect than the passive power filter (PPF), but APF needs a complex
regulation and control system, especially a large power harmonic-generating source, which is inapplicable in
current HVDC transmission’s ac system [11]–[13]. A patent named coupling-compensation and harmonic-
shielding converter transformer, that is, the new converter transformer, proposes an ideal solution to harmonic
suppression.
Fig. 1. Traditional converter transformer with ac filters.
(a) Wiring mode. (b) Voltage phasor diagram.
Problems Of Traditional Converter Transformer’s Wiring Mode And Ac Filtering Scheme
As Fig. 1 shows, the traditional converter transformer and ac passive filtering method are commonly
used in 12-pulse HVDC system. It is clear that the transformer adopts wye/wye/delta wiring, and ac filters are
placed at the transformer’s primary side. Although this kind of converter transformer and passive filters are
widely applied in HVDC systems, these structures and designs still have some disadvantages.
2. A New Filtering Method and a Novel Converter Transformer for HVDC System.
www.iosrjournals.org 71 | Page
1) In HVDC transmission systems, the converter is the main harmonic-generating source. A three-phase
bridge converter usually generates characteristic harmonic currents at the ac side because of the turning
of the thyristors [14]. The noncharacteristic harmonic currents can also be generated due to some
factors, such as various unbalances in ac voltages, system impedance, and transformer parameters [15].
All the harmonic currents will flow in the primary and secondary windings of the traditional converter
transformer, which increases the transformer’s additional heat, vibration, and noise. As a result, it
increases the added loss, the difficulty of insulating design, the capacity of the transformer, and the
margin of the design capability, which increases the cost of the traditional converter transformer.
2) In the ac system of HVDC, traditional passive filtering is the main method of harmonic suppression.
However, it still has several disadvantages. The most serious one is that the series/parallel resonance
may occur between the system impedance and the passive power filters. This series/ parallel resonance
will result in the amplification of harmonic current and harmonic voltage, and it may damage the
passive power filters and neighboring power equipment [16], [17]. To avoid the resonance of the
passive power filters, the tuned frequency of passive power filters is designed slightly away from the
dominant harmonic frequency. However, it will degrade the performance of the passive power filter,
and the filtering effect of the traditional passive filter cannot be optimal.
Technical Characteristics Of New Converter Transformer And Corresponding Inductive
Filtering Method
Fig. 2 shows the new converter transformer and the corresponding inductive filtering system, in
which, (a) shows the wiring mode of the transformer, and its secondary winding adopts prolonged-delta wiring.
To facilitate our discussion, the winding of Ai - ai ,Bi - bi,,Ci- ci (i=1,2) is called aprolonged winding, and the
winding of a1-b1,b1-c1,c1-a1 ,a2-c2,b2-a2,c2-a2 is called common winding. (b) shows the transformer’s voltage
phasor diagram, which is used to discuss the phase-shifting of the new transformer. (c) shows the arrangement
of the inductive filters. As can be seen from (c), a tap at the linking point of each single-phase prolonged
winding and common winding is connected with double-tuned (DT) filters. The inductive filtering method will
be discussed later on in this paper.
Fig. 2. New converter transformer and corresponding inductive filtering system. (a) Wiring mode . (b) Voltage
phasor diagram. (c) Arrangement of filters.
A. Phase-Shifting Principle
In order to satisfy the demand of 12-pulse HVDC, the converter transformer has to supply 12-phase
commutating line voltage. The secondary winding of the traditional transformer adopts wye/delta wiring, and
the phase angle difference between the wye winding’s line-voltage and the delta winding’s line-voltage has to
be 30o
, which is shown in Fig. 1(b). As for the new converter transformer, according to Fig. 2(b), we can set the
phase angle difference between the line-voltage VC-A and the VC1-A1 to -15o
, and set the phase angle difference
between the line-voltage VC-A and theVC2-A2 to +15o
. In this way, the phase angle difference between the line-
voltage VC1-A1and the VC2-A2 is 30o
. So we can deduce that the phase-shifting angle Ɵ should be 15o
(ᴨ/12) . Set
that the voltage value of the primary winding of the new converter transformer is V1 , the voltage value of the
secondary prolonged winding is V2 , and the voltage value of the secondary common winding isV3 ; then,
according to Fig. 2(b) and sine rule, the following can be obtained:
V3 / sin (ᴨ/12) = (V3 + V2) / sin(ᴨ/4)
= √ 3 V1 / sin(2ᴨ/3) (1)
According to the above equation, the turn-ratio can be obtained as follows
3. A New Filtering Method and a Novel Converter Transformer for HVDC System.
www.iosrjournals.org 72 | Page
K3 = N3/N1 = V3/V1 = 0.5176
K2 = N2/N1 = V2/V1 = 0.8966 (2)
in which K3,K2 respectively, represent the turn-ratio of the secondary prolonged winding and the common
winding to primary winding.N1,N2,N3 and are the turn number of the primary winding, the secondary common
winding, and the prolonged winding, respectively.
In the actual HVDC systems, the new converter transformer can adopt the single-phase three-winding
method. As long as the relation of the turn-ratio satisfies (2), the new converter transformer can supply 12-phase
commutating line voltage and satisfy the commutating demand of the 12-pulse converter
B. Self-Coupling Action
The secondary prolonged winding and the common winding of the new converter transformer adopt
self-coupling connection, which is similar to the series winding and the common winding of autotransformer
[17], [18]. According to Fig. 2(c), set that the output line-voltage is VL , the voltage of the common winding is
Vd and the voltage of the prolonged winding is Ve; then, the following voltage phasor diagram in Fig. 3 can be
obtained.
Fig. 3. Voltage phasor diagram for secondary winding’s analysis
According to cosine rule, the output line-voltage can be expressed as follows
VL
2
= ( Ve+ Vd)2
+ Ve
2
-2Ve (Ve+Vd) cos (2ᴨ/3) (3)
Then, the voltage of the secondary prolonged winding is deduced as follows:
Ve = -Vd / 2 + √ ((VL
2
/3) – (Vd
2
/12)) (4)
The secondary prolonged and common winding of the new converter transformer is electromagnetic
coupling, which is similar to the series and commonwinding of the autotransformer. When the prolonged
winding and the common winding maintain magnetic force balance, we can obtain the following relation:
Ve Ie =Vd Id (5)
in which Ie and Id are the root-mean-square (RMS) current of the secondary prolonged winding and the common
winding, respectively.
Fig. 2(c) shows that the current of the secondary prolonged winding is equal to the output current , and
its electromagnetic capacity can be expressed as follows:
Se = 3 VeIo (6)
Meanwhile, the output capacity can be expressed as follows:
So = √3 VL Io (7)
Then, the ratio coefficient can be obtained as follows, which is used to analyze the material utilizing
ratio of the transformer:
α = Se / So = √3 Ve / VL (8)
Assuming that the output line-voltage value VL the new converter transformer is 110 kV, and voltage
value of the secondary common winding is 35 kV, then, according to (4)–(8), we can obtain the ratio coefficient
α=0.681<1 , which indicates that new converter transformer is material saving.
4. A New Filtering Method and a Novel Converter Transformer for HVDC System.
www.iosrjournals.org 73 | Page
C. Inductive Filtering Mechanism
Fig. 4. New converter transformer’s single-phase harmonic model.
Fig. 4 shows the single-phase model of the new converter transformer, which is used to analyze the
inductive filtering mechanism. In this figure,Ih indicates the harmonic current source, which is also the harmonic
current of the secondary prolonged winding. Ih1 and Ih3 indicate the harmonic current of the primary winding
and the secondary common winding, respectively. Because of the harmonic current Ih of the secondary
prolonged winding, the primary winding and the secondary common winding will induce harmonic current Ih1
and Ih3 to balance Ih .
According to magnetic force balance, the following results:
N2Ih = N3 Ih3 + N1 Ih1 (9)
in which N1 ,N2,N3 ,and are the turn number of the primary winding, the secondary prolonged winding, and the
common winding, respectively.
If the harmonic ampere-turns of the secondary prolonged winding and those of the common winding
can keep balance, then Ih1 = 0 , that is, there will be no induction harmonic current in the primary winding. That
is to say, the harmonic currents only flow in the secondary winding of the new transformer. To realize the
inductive filtering method, it not only needs the full tuning design of the tapping filter, but also needs the zero
inductance design of the secondary common winding of the new converter transformer, which will be analyzed
in the following equivalent circuit of the single-phase transformer shown in Fig. 5.
Fig. 5. Single-phase model of the new converter transformer. (a) Winding arrangement. (b) Equivalent circuit.
Fig. 5(a) shows the winding arrangement of the single-phase model of the new converter transformer.
According to short-circuit test, we can measure the short-circuit impedance Z12, Z13 and Z23 . Then, the
equivalent impedance shown in Fig. 6(b) can be expressed as follows:
Z1 = 0.5( Z12 + Z13 - Z23
1
)
Z2
1
= 0.5( Z12 + Z23
1
- Z13)
Z3
1
= 0.5( Z13 + Z23
1
- Z12) (10)
By regulating the winding arrangement shown in Fig. 5(a), it can realize the goal that the impedance
Z3
1
of the secondary common winding is approximately equal to 0 (the resistance can be ignored for high-
capacity converter transformers). In Fig. 5(b), the solid arrow and the virtual arrow, respectively, indicate basic
frequency current and harmonic frequency current. Under the specific harmonic frequency of the harmonic
current that needs suppressing, both of the double-tuned filter and the harmonic impedance of the secondary
common winding are approximately 0, so the harmonic current mainly flows into the branch of the secondary
common winding, and there is approximately no harmonic current in the primary winding.
In addition, under the fundamental frequency, the impedance of the filter is capacitive, thus providing
reactive power compensation.
5. A New Filtering Method and a Novel Converter Transformer for HVDC System.
www.iosrjournals.org 74 | Page
Fig. 6. New HVDC transmission analogy system with new converter transformer in rectifier station and
traditional converter transformer in inverter station.
II. System Simulation Study
A. Simulation Model
In order to prove the correctness of the above analyses, according to the new HVDC transmission
testing system shown in Fig. 6, we have established a system simulation model by using
MATLAB/SIMULINK. Fig. 6 shows the rectifier station with the new converter transformer and in the
corresponding inductive filtering method and the inverter station with the traditional converter transformer and
in the passive filtering method. It is necessary to clarify that the double-tuned filter (DT5/7) is not needed when
we consider suppressing fifth and seventh harmonic currents in the wiring method of the new converter
transformer in the rectifier station. Here, due to the high content of fifth and seventh harmonics, in order to
remove their negative effect of fifth and seventh harmonics on the converter transformer, we have designed the
DT5/7. In Fig. 7, HP2 indicates the second-order high-pass filter; Zr and Zi, respectively, indicate the system
impedance of the rectifier and the inverter side, and and Ldr ,Ldi respectively, indicate the inductance of the
rectifier and the inverter side.
Fig. 7. Phase current fast Fourier transform (FFT) of the secondary terminal of the traditional and the new
converter transformer. (a) FFT of secondary phase current IA1 corresponding to Fig. 1. (b) FFT of
secondary phase current IA1 corresponding to Fig. 2.
Fig. 8. Phase current FFT of the primary terminal of the traditional and the new converter transformer.
(a) FFT of primary phase current IA corresponding to Fig. 1.
(b) FFT of primary phase current IA corresponding to Fig. 2.
B. Contrast Analysis of Simulation Results
Fig. 7 shows the phase current FFT of the secondary terminal of the traditional converter transformer
and that of the new converter transformer. It can be seen that the harmonic content of each order of the
traditional and the new converter transformers is similar, which is determined by the nonlinear load, that is, the
converter. However, as for the primary phase current of the transformer shown in Fig. 8, it can be seen that the
primary phase-current waveform of the new converter transformer is better than that of the traditional one,
which is determined by the wiring method of the transformer and by the filtering method. We can see that
adopting the new winding wiring and the inductive filtering method can effectively suppress the 5th, 7th, 11th,
6. A New Filtering Method and a Novel Converter Transformer for HVDC System.
www.iosrjournals.org 75 | Page
and 13th harmonic currents that only flow in the secondary winding of the new transformer, so the THD shown
in Fig. 8(b) is lower than that in Fig. 8(a). Table I shows the FFT value of the exact harmonic contents of Figs. 7
and 8, which further proves the correctness of the above analysis.
TABLE I: Comparison of the harmonic content of the secondary sides of the new and the traditional converter
transformers
Fig. 9 shows the phase current FFT at the grid side of the rectifier and the inverter station,
respectively.We can see that the waveform of the phase current in Fig. 9(a) is better than that in Fig 9(b), which
is caused by the new inductive filtering method Considering the effect of the system impedance, the resonance
point of the passive filters cannot be reached. So the filtering effect is not ideal, as shown in Fig. 9(b). While
adopting the inductive filtering method, the harmonic currents are confined by the coupling-windings of the new
converter transformer, so the resonance point of the tap filters can be reached. Therefore, we can obtain the ideal
phase current waveform at the grid side shown in Fig. 9(a).Acomparison of the exact harmonic contents is
shown in Table II.
TABLE II : Comparison of the harmonic content of the grid sides of the rectifier station and the inverter station
Fig. 9. Phase current FFT at the grid side of the rectifier station and the inverter station, respectively.
(a) FFT of phase current IAG at the grid side of the rectifier station corresponding to Fig. 6.
(b) FFT of phase current IAG at the grid side of the inverter station corresponding to Fig. 6.
III. Conclusion
In 12-pulse HVDC transmission systems, the secondary windings of the new converter transformer
adopt prolonged delta wiring, which brings about good symmetrical characteristics to its structure. Each phase
short-circuit impedance can be equal. It can facilitate the reliable commutation and the sound operation of the
converter. The equivalent impedance of the secondary common winding is approximately 0, which provides
good conditions for inductive filtering. The resonance point of the tap filters of the new transformer can be
reached without the consideration of the effect of the system impedance. Simulation results verify the
correctness of our theoretical analysis, and show that the filtering effect of the inductive filtering method is
better than that of the traditional passive filtering method. Adopting the new converter transformer and the
corresponding inductive filtering method can optimize the structure of HVDC transmission systems, greatly
7. A New Filtering Method and a Novel Converter Transformer for HVDC System.
www.iosrjournals.org 76 | Page
reducing the negative effect of harmonic on the operation of the transformer and improving the filtering effect at
the ac side of HVDC systems.
References
[1]. B. R. Anderson, ―HVDC transmission-opportunities and challenges,‖ in AC and DC Power Transmission, 2006, Proc. 8th Inst. Elect.
Eng. Int. Conf., Mar. 28–31, 2006, pp. 24–29.
[2]. C. Wolff and T. Elberling, ―The Kontek HVDC link between denmark and germany,‖ in Proc. IEEE Power Eng. Soc. Winter
Meeting, Jan. 23–27, 2000, vol. 1, pp. 572–574.
[3]. B. Gemmel and J. Loughran, ―HVDC offers the key to untrapped hydro potential,‖ IEEE Power Eng. Rev., vol. 22, no. 5, pp. 8–11,
May 2002.
[4]. J. Alan, C. Forresta, and B. Allard, ―Thermal problems caused by harmonic frequency leakage fluxes in three-phase, three-winding
converter transformers,‖ IEEE Trans. Power Del., vol. 19, no. 1, pp. 208–213, Jan. 2004.
[5]. J. Alan and C. Forrest, ―Harmonic load losses in HVDC converter transformers,‖ IEEE Trans. Power Del., vol. 6, no. 1, pp. 153–157,
Jan. 1991.
[6]. M. J. Heathcote, The J&P Transformer Book, 25 ed. Oxford, U.K.: Reed, 1998.
[7]. K. Eckholz and P. Heinzig, ―HVDC-transformer-a technical challenge,‖ in Proc. IEEE Int. Conf. Power Syst. Technol., Oct. 13–17,
2002, vol. 1, pp. 547–551.
[8]. J. C. Das, ―Passive filters-potentialities and limitations,‖ IEEE Trans. Ind. Applicat., vol. 40, no. 1, pp. 232–241, Jan.–Feb. 2004.
[9]. H.-L. Jou, J.-C. Wu, and K.-D. Wu, ―Parallel operation of passive power filter and hybrid power filter for harmonic suppression,‖
Proc. Inst. Elect. Eng. Generation, Transmission, Distribution, vol. 148, no. 1, pp. 8–14, Jan. 2001.
[10]. D. Rivas, L. Moran, J. W. Dixon, and J. R. Espinoza, ―Improving passive filter compensation performance with active techniques,‖
IEEE Trans. Ind. Electron., vol. 50, no. 1, pp. 161–170, Feb. 2003.
[11]. W. Zhang, A. Aberg, U. Jonsson, and O. Loof, ―Active DC filter for HVDC system—A test installation in the Konti–Skan DC link at
Lindome converter station,‖ IEEE Trans. Power Del., vol. 8, no. 3, pp. 1599–1606, Jul. 1993.
[12]. T. Westerweller, M. Pereira, H. Huang, and G. Wild, ―Performance calculation and operating results of active AC harmonic filters
for HVDC transmission systems,‖ in Proc. IEEE Power Eng. Soc. Summer Meeting, Jul. 15–19, 2001, vol. 1, pp. 337–342.
[13]. D. Basic, V. S. Ramsden, and P. K. Muttik, ―Harmonic iltering of high-power 12-pulse rectifier loads with a selective hybrid filter
system,‖ IEEE Trans. Ind. Electron., vol. 48, no. 6, pp. 1118–1127, Dec. 2001.
[14]. R. Zhena, Z. Yan, and D. Baoming, ―Optimization model and algorithm of type-c damped filter in high voltage direct current
transmission system,‖ in Proc. CSEE, Dec. 2002, vol. 22, no. 22, pp. 123–126.
[15]. C.-K. Kim, B.-M. Yang, Y.-H. Kim, and H.-W. Rhem, ―HVDC performance analysis according to ER-filter and single tuned filter,‖
in Proc. 29th Annu. Conf. IEEE Ind. Electron. Soc., Nov. 2–6, 2003, vol. 3, pp. 2655–2659.
[16]. H.-L. Jou, J.-C. Wu, and K.-D. Wu, ―Parallel operation of passive power filter and hybrid power filter for harmonic suppression,‖
Proc. Inst. Elect. Eng. Generation, Transmission, Distribution, vol. 148, no. 1, pp. 8–14, Jan. 2001.
[17]. B. Singh, G. Bhuvaneswari, and V. Grag, ―T-connected autotransformer- based 24-pulse ac-dc converter for variable frequency
induction motor drives,‖ IEEE Trans. Energy Conv., vol. 21, no. 3, pp. 663–672, Sep. 2006
Author’s detail
Mr.A.Hema Sekhar Currently Pursuing Ph.D.degree in SVU College of Engineering .He is
Presently working as Associate Professor in Sri Venkatesa Perumal College of Engineering
& Technology,Puttur. he received his B.Tech in EEE from JNT University,Hyderabad,at
SVEC,A.Rangampet.he received his M.Tech in PSOC from SV University College of
Engineering,Tirupati. His area of interest are power systems,Distribution Systems,Electrical
Machines and Power system Stability & Control,power system optimizations .
Mrs.A.Lakshmi Devi She is currently working as Professor in SV University College of
Engineering,Tirupati.She received her B.Tech in Electrical & Electronics Engineering from SV
University College,Tirupati and M.E from IISc,Bangolore and Ph.D from SV University
,Tirupati. Her Area of interest are load flow studies,load frequency control,Reactive power
control,Power system operation & Control and power system stability.