This document summarizes a research paper on a hybrid active power filter with a control scheme to compensate industrial power supplies. The hybrid active power filter combines a passive filter with an active power filter to compensate for non-linear loads. It can improve power factor and eliminate lower harmonic currents simultaneously. The control scheme uses a microcontroller to calculate the compensating current needed from the active filter based on measurements of the load and line currents. Experimental results showed the hybrid active power filter provided better compensation of harmonics compared to just a passive filter. It allowed the input current, voltage, and compensated output current to be closer to sinusoidal waveforms.
POWER HARMONICS- SOURCES, ISSUES AND MITIGATIONASHIKS842
Various developments in the field of power system are being carried out to find a fruitful solution to mitigate the harmonics. some of the basic solutions are being described here.
SEMINAR PRESENTED ON 21 JANUARY 2017 CONDUCTED BY KERALA STATE ELECTRICITY BOARD ENGINEER'S ASSOCIATION.
The presentation is delivering the general aspects of transmission of electric energy. At the beginning need of transmission is presented, and then the various aspects of transmission, which affect the choice of scheme of transmission are presented. At the end of presentation, the topic is summarized as comparison among the HVAC and HVDC transmission.
This presentation was given by shivlal mohal, during the final semester of electric engineering.
POWER HARMONICS- SOURCES, ISSUES AND MITIGATIONASHIKS842
Various developments in the field of power system are being carried out to find a fruitful solution to mitigate the harmonics. some of the basic solutions are being described here.
SEMINAR PRESENTED ON 21 JANUARY 2017 CONDUCTED BY KERALA STATE ELECTRICITY BOARD ENGINEER'S ASSOCIATION.
The presentation is delivering the general aspects of transmission of electric energy. At the beginning need of transmission is presented, and then the various aspects of transmission, which affect the choice of scheme of transmission are presented. At the end of presentation, the topic is summarized as comparison among the HVAC and HVDC transmission.
This presentation was given by shivlal mohal, during the final semester of electric engineering.
The concept of FACTS (Flexible Alternating Current Transmission System) refers to a family of power electronics-based devices able to enhance AC system controllability and stability and to increase power transfer capability.
The significance of power factor correction (PFC) has long been visualized as a technology requirement for improving the efficiency of a power system network by compensating for the fundamental reactive power generated or consumed by simple inductive or capacitive loads. With the Information Age in full swing, the growth of high reliability, low cost electronic products have led utilities to escalate their power quality concerns created by the increase of such “switching loads.” These products include: entertainment devices such as Digital TVs, DVDs, and audio equipment; information technology devices such as PCs, printers, and fax-machines; variable speed motor drives for HVAC and white goods appliances; food preparation and cooking products such as microwaves and cook tops; and lighting products, which include electronic ballasts, LED and fluorescent lamps, and other power conversion devices that operate a variety of lamps. The drivers that have resulted in this proliferation are a direct result of the availability of low-cost switch-mode devices and control circuitry in all major end-use segments: residential, commercial, and industrial.
Power Quality is a combination of Voltage profile, Frequency profile, Harmonics contain and reliability of power supply.
The Power Quality is defined as the degree to which the power supply approaches the ideal case of stable, uninterrupted, zero distortion and disturbance free supply.
Introduction
Definition of FACTS system
Necessity of facts devices
Shunt connected controllers
Types of facts controllers
Shunt connected controllers
Benefits of FACTS
The concept of FACTS (Flexible AC Transmission System) refers to a family of power electronics based devices able to enhance AC system controllability and stability and to increase power transfer capability.
The design of the different schemes and configurations of FACTS devices is based on the combination of traditional power system components (such as transformers, reactors, switches, and capacitors) with power electronics elements (such as various types of transistors and thyristors).
Nowadays, it is very important to maintain voltage level. Controlling of that voltage is also important. This Presentation contains methods of voltage control.
This directional over current relay employs the principle of actuation of the relay....It has a metallic disc free to rotate between the poles of two...
In the modern power system the reactive power compensation is one of the main issues, the transmission of active power requires a difference in angular phase between voltages at the sending and receiving points (which is feasible within wide limits), whereas the transmission of reactive power requires a difference in magnitude of these same voltages (which is feasible only within very narrow limits). The reactive power is consumed not only by most of the network elements, but also by most of the consumer loads, so it must be supplied somewhere. If we can't transmit it very easily, then it ought to be generated where it is needed." (Reference Edited by T. J. E. Miller, Forward Page ix).Thus we need to work on the efficient methods by which VAR compensation can be applied easily and we can optimize the modern power system. VAR control technique can provides appropriate placement of compensation devices by which a desirable voltage profile can be achieved and at the same time minimizing the power losses in the system. This report discusses the transmission line requirements for reactive power compensation. In this report thyristor switched capacitor is explained which is a static VAR compensator used for reactive power management in electrical systems.
Seminar Topic For Electrical and Electronics Engineering (EEE)
report of Improvement of the Electric Power Quality Using Series Active and S...Vikram Rawani
The increase of nonlinear loads due to the proliferation of electronic equipment causes power quality in the power system to deteriorate. Harmonic current drawn from a supply by the nonlinear load results in the distortion of the supply voltage waveform at the point of common coupling (PCC) due to the source impedance. Both distorted current and voltage may cause end-user equipment to malfunction, conductors to overheat and may reduce the efficiency and life expectancy of the equipment connected at the PCC.
The concept of FACTS (Flexible Alternating Current Transmission System) refers to a family of power electronics-based devices able to enhance AC system controllability and stability and to increase power transfer capability.
The significance of power factor correction (PFC) has long been visualized as a technology requirement for improving the efficiency of a power system network by compensating for the fundamental reactive power generated or consumed by simple inductive or capacitive loads. With the Information Age in full swing, the growth of high reliability, low cost electronic products have led utilities to escalate their power quality concerns created by the increase of such “switching loads.” These products include: entertainment devices such as Digital TVs, DVDs, and audio equipment; information technology devices such as PCs, printers, and fax-machines; variable speed motor drives for HVAC and white goods appliances; food preparation and cooking products such as microwaves and cook tops; and lighting products, which include electronic ballasts, LED and fluorescent lamps, and other power conversion devices that operate a variety of lamps. The drivers that have resulted in this proliferation are a direct result of the availability of low-cost switch-mode devices and control circuitry in all major end-use segments: residential, commercial, and industrial.
Power Quality is a combination of Voltage profile, Frequency profile, Harmonics contain and reliability of power supply.
The Power Quality is defined as the degree to which the power supply approaches the ideal case of stable, uninterrupted, zero distortion and disturbance free supply.
Introduction
Definition of FACTS system
Necessity of facts devices
Shunt connected controllers
Types of facts controllers
Shunt connected controllers
Benefits of FACTS
The concept of FACTS (Flexible AC Transmission System) refers to a family of power electronics based devices able to enhance AC system controllability and stability and to increase power transfer capability.
The design of the different schemes and configurations of FACTS devices is based on the combination of traditional power system components (such as transformers, reactors, switches, and capacitors) with power electronics elements (such as various types of transistors and thyristors).
Nowadays, it is very important to maintain voltage level. Controlling of that voltage is also important. This Presentation contains methods of voltage control.
This directional over current relay employs the principle of actuation of the relay....It has a metallic disc free to rotate between the poles of two...
In the modern power system the reactive power compensation is one of the main issues, the transmission of active power requires a difference in angular phase between voltages at the sending and receiving points (which is feasible within wide limits), whereas the transmission of reactive power requires a difference in magnitude of these same voltages (which is feasible only within very narrow limits). The reactive power is consumed not only by most of the network elements, but also by most of the consumer loads, so it must be supplied somewhere. If we can't transmit it very easily, then it ought to be generated where it is needed." (Reference Edited by T. J. E. Miller, Forward Page ix).Thus we need to work on the efficient methods by which VAR compensation can be applied easily and we can optimize the modern power system. VAR control technique can provides appropriate placement of compensation devices by which a desirable voltage profile can be achieved and at the same time minimizing the power losses in the system. This report discusses the transmission line requirements for reactive power compensation. In this report thyristor switched capacitor is explained which is a static VAR compensator used for reactive power management in electrical systems.
Seminar Topic For Electrical and Electronics Engineering (EEE)
report of Improvement of the Electric Power Quality Using Series Active and S...Vikram Rawani
The increase of nonlinear loads due to the proliferation of electronic equipment causes power quality in the power system to deteriorate. Harmonic current drawn from a supply by the nonlinear load results in the distortion of the supply voltage waveform at the point of common coupling (PCC) due to the source impedance. Both distorted current and voltage may cause end-user equipment to malfunction, conductors to overheat and may reduce the efficiency and life expectancy of the equipment connected at the PCC.
Improvement of the electric power quality usingVikram Rawani
A control algorithm for a three-phase hybrid power
filter is proposed.It is constituted by a series active filter and a passive filter connected in parallel with the load.
Harmonic Compensation for Non Linear Load Using PWM Based Active Filteridescitation
In this paper the elimination of the current harmon-
ics of injected by nonlinear loads is investigated. The active
power filter proposed in this study is a Single phase voltage
source inverter (VSI) connecting to the AC mains. The dspic
controller is used to control the operation of the switches of
the inverter. Active filtering is achieved through PWM in-
verter connected next to a given nonlinear load or at the point
of the common coupling (PCC). The simulation results show
that how well the filter eliminates the harmonics of the source
current.
Mitigation of Harmonic Current through Hybrid Power Filter in Single Phase Re...IDES Editor
This paper presents a single-phase Hybrid Power
Filter (HPF) for harmonics and reactive power compensation.
This proposed topology reduces the rating and size of the
filter components. A combination of Passive and Active Filter
is proposed for reducing the rating of filter. In the proposed
technique Passive Filter (PF) is tuned to compensate 3rd and
5th order harmonics and Active Power Filter (APF) compensates
all remaining harmonic components which are not
compensated by passive filter. A half bridge inverter with DC
bus capacitor is used as active filter. It has only two power
switches. The active power filter control is based on DC side
voltage control. The effectiveness of the proposed algorithm
is demonstrated by its simulation in PSIM software. The
simulation results show that the designed hybrid filter
compensate the harmonic currents produced by loads and the
power factor, making the current at the source side to become
sinusoidal and in phase with the system voltage.
Performance analysis of three phase shunt hybrid active power filtereSAT Journals
Abstract Active filtering of electric power has now become a mature technology for harmonic and reactive power Compensation in AC networks. The past several years have seen a rapid increase of power electronics-based loads connected to low and medium voltage power distribution systems. These loads draw non-sinusoidal current from the mains, degrading the power quality by causing harmonic distortion. This paper proposes a three phase Shunt Hybrid Active Filter (SHAF) topology for harmonic reduction and power factor improvement in low voltage power distribution systems. The compensation current reference for the proposed SHAF topology is obtained by using synchronous reference frame theorem. This theorem simplifies the equations for the current reference estimation in d-q co-ordinates thus leading to a more efficient and fast computation. To generate the compensation current that follows the current reference, the hysteresis current control method is adopted for 2-level VSI in low voltage system, the system is verified by developing simulation model using MATLAB/Simulink simulation package and the results are presented. The performance of shunt active filter and the proposed shunt hybrid active filter topology in reducing total harmonic distortion (THD) is compared for low voltage distribution system. Keywords: SAPF, SHPF, PI control, THD, Hysteresis current pulse width modulation, D-Q reference frame theory.
What is a Smart Grid?
The Smart Grid Enables the ElectriNetSM
Local Energy Networks
Electric Transportation
Low-Carbon Central Generation
What Should Be the Attributes of the Smart Grid?
Why Do We Need a Smart Grid?
Is the Smart Grid a “Green Grid”?
Alternative Views of a Smart Grid
Mitigation of the Harmonics under Reactive Power Compensation by SHPF-TCR Usi...IJERA Editor
In this paper, a combined system of a thyristor-controlled reactor (TCR) and a shunt hybrid power filter
(SHPF)has been designed by MATLAB/SIMULINK approach for harmonic and reactive power compensation.
The quality of the power is effected by many factors like harmonic contamination, due to the increment of nonlinear
loads, sag and swell due to the switching of the loads etc. Also control schemes based on PI and Fuzzy
logic controllers have been proposed to mitigate the harmonics and neutral current . The proposed methodology
not only reduces the complexity but also offers simplicity to implement and increases reliability of the system.
These control strategies also help in achieving a low cost highly effective control. The performance is also
observed under influence of utility side disturbances such as harmonics, flicker and spikes with Non-Linear and
Reactive Loads with different control strategies.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
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Power system harmonics are a menace to electric power system with disastrous consequence. Due to the presence of non linear load, power quality of the system gets affected. To overcome this, shunt active power filter have been used near harmonic producing loads or at the point of common coupling to block current harmonics. The shunt active power filter is designed to minimize harmonics in source current and reactive power in the non linear power supplies which are creating harmonics. In this paper, Instantaneous power of p-q theory is employed to generate the reference currents and PI controller is used to control the dc link voltage. In addition to this, Artificial Intelligence (AI) technique is used to minimize the harmonics produced by nonlinear load. The main objective of this paper is to analyze and compare THD of the source current with PI controller and by artificial neural network based back propagation algorithm. The proposed system is designed with MATLAB/SIMULINK environment.
Distribution Static Synchronous Compensator (DSTATCOM) is a shunt compensating device which is used
to improve current profile by exchanging of reactive power with unbalanced and nonlinear load. DSTATCOM is a
shunt compensating device used for power quality improvement in distribution systems. Relevant solutions are
applied for harmonics, fluctuation of voltage, voltage deviation, unbalance of three phase voltage and current and
frequency deviation. Different controlling schemes such as Phase Control Method (PCM), Fryze Power Theory
(FPT), Synchronous Reference Frame Theory (SRFT) and Instantaneous Reactive Power Theory (IRPT) are used
for reactive power compensation with the help of Voltage source Inverter (VSI). In this project we are going to
balance the source current using different control schemes. The results of different source currents are compared
with a different control schemes in terms of active and reactive power and in terms of Total Harmonic Distortion
(THD) for nonlinear load using Fryze Power Theory (FPT) and Instantaneous Reactive Power Theory (IRPT).
Reference currents are generated by the different control schemes have been dynamically traced in a hysteresis
current controller. The performance of DSTATCOM for different control schemes is validated for load balancing
and harmonic elimination by using simulation models in MATLAB/SIMULINK
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Power System Harmonic Compensation Using Shunt Active Power FilterIJERA Editor
This paper shows the method of improving the power quality using shunt active power filter. The proposedtopic comprises of PI controller, filter hysteresis current control loop, dc link capacitor. The switching signal generation for filter is fromhysteresis current controller techniques. With the all these element shunt active power filter reduce the total harmonic distortion. Thispaper represents the simulation and analysis of the using three phase three wire system active filter to compensate harmonics .Theproposed shunt active filter model uses balanced non-linear load. This paper successfully lowers the THD within IEEE norms and satisfactorily works to compensatecurrent harmonics.
POWER STABILITY ANALYSIS OF A TRANSMISSION SYSTEM WITH A UNIFIED POWER FLOW C...IJITE
The unified power quality conditioner is the equipment used for regulated voltage distortion and voltage
unbalance in a power system. UPFC can enhance the power to flow through the transmission system by
controlling the power flow and voltage stability of the transmission line within their limits. This paper
presents a control scheme and Theoretical derivation of the unified power flow conditioner and the
simulation results are compared and contrasted in detail. UPFC is a combination of shunt Active and
series active power filters. UPFC contains a DC link capacitor in a single-phase voltage source inverter
with two back to back connected, three-phase three-wire and three-phase four-wire are arranged. The
fundamental target of this work is to determine the causes and impacts of power quality problems,
specifically voltage sag, voltage swell, power factor, and Total Harmonics Distortion (THD) and enhance
the power quality of a transmission system by UPFC based Transformative Intrinsic Algorithm (TIA). The
Simulation of the proposed method is developed by Mat lab Simulink software, and the simulation result
shows, the proposed method gives better solutions to control the power imbalance in the distribution
system with its cost-effectiveness.
Power factor correction using bridgeless boost topologyDHEERAJ DHAKAR
Power quality is becoming a major concern for
many electrical users. The high power non linear loads
(such as adjustable speed drives, arc furnace, static power
converter etc) and low power loads (such as computer, fax
machine etc) produce voltage fluctuations, harmonic
currents and an inequality in network system which results
into low power factor operation of the power system. The
devices commonly used in industrial, commercial and
residential applications need to go through rectification for
their proper functioning and operation. Due to the
increasing demand of these devices, the line current
harmonics create a major problem by degrading the power
factor of the system thus affecting the performance of the
devices. Hence there is a need to reduce the input line
current harmonics so as to improve the power factor of the
system. This has led to designing of Power Factor
Correction circuits. Power Factor Correction (PFC)
involves two techniques, Active PFC and Passive PFC. An
active power factor circuit using Boost Converter is used for
improving the power factor. This thesis work analyzes the
procedural approach and benefits of applying Bridgeless
Boost Topology for improving the power factor over Boost
Converter Topology. A traditional design methodology
Boost Converter Topology is initially analyzed and
compared with the Bridgeless Boost topology and the
overall Power Factor (PF) can be improved to the
expectation. Method of re-shaping the input current
waveform to be similar pattern as the sinusoidal input
voltage is done by the Boost converter and the related
controls that act as a Power Factor Correction (PFC)
circuit. Higher efficiency can be achieved by using the
Bridgeless Boost Topology. In this paper simulation of Boost
Converter topology and Bridgeless PFC boost Converter is
presented. Performance comparisons between the
conventional PFC boost Converter and the Bridgeless PFC
Boost Converter is done.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
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Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
2. 108
Kalpana. K, Madhumathi. M. A & Madhumitha M
interestingly these new generation equipments are more sensitive to power quality problems such as harmonics. Secondly
these harmonics creates various adverse effects in the power system. More over the customers are becoming more and
more aware about the financial impacts of the power quality problems such as harmonics, reactive power, transients etc.
Hence it becomes essential for the customers as well as the utilities to limit the harmonic distortion and reactive power
consumption to minimum. One of the solutions to limit the harmonic distortion and power factor correction is the use of
filters.
HYBRID ACTIVE POWER FILTER
The hybrid active power filter is nothing but the series combination of active power filter and the passive
elements. The harmonics in the power system can be removed in the following ways.
By providing a low impedance path to ground for harmonic signal.
By injecting compensating signals which are in phase opposition with the harmonic signal present in the system.
o
For the first one we can use passive tuned filter and for the latter active filter can be used.
o
Active filter is connected in series with the passive filter through a coupling transformer.
Figure 1: PWM VSI Unit
Figure 2: Hybrid Active Power Filter
ACTIVE POWER FILTER
The basic concept of active power filter is that, a harmonic current or voltage can be eliminated by injecting the
same harmonic component of current or voltage with equal magnitude and opposite phase. This concept can be
implemented using power electronics switches such as IGBT’s, & MOSFET’s and advanced microcontrollers. Apart from
compensating the harmonics, the active power filters can supply the reactive power required for the load. Thus, an active
power filter can compensate for a wide range of harmonic components and at the same time improve the power factor of
the current. The basic functions of an active power filter can be summarized as,
Harmonic compensation, harmonic isolation, harmonic damping and harmonic Termination.
3. A Hybrid Active Power Filter with Control Scheme for the Effective Compensation of Industrial Power Supply
Reactive power compensation.
109
Negative sequence current/voltage compensation.
The passive filter is the combination of resistance, inductance, and capacitance element and tuned to control the
particular harmonic frequencies.
PROPOSED SYSTEM
Figure 3: Block Diagram of the Proposed Filter Unit
In this paper we deal with the reactive power compensation using PWMVSI active filter with the shunt passive
filter to eliminate the harmonics.
Voltage Source Inverter
IRF840 MOSFETS are used here (figure.4). Inverter Used here is a voltage source inverter, which is used to
switch the supply from the capacitor to the distribution line. It also consists of a diode connected anti parallel to the
MOSFET inside will charge the capacitor with the supply voltage.
Switching speed depends on the pulse produced by the dsPIC microcontroller based on the values obtained for the
compensation current. Its turn off time is 90ns. The voltage that is stored in the capacitor is discharged to the supply line
through this inverter circuit. The capacitor will in turn get charged via the diode connected anti parallel to the MOSFET
inside the chip.
Due to non linear load the current wave form will got distorted by harmonics, so to eliminate the harmonic current
we are injecting the same value of current with the help of an inverter and the dc storage capacitor.
The switching pulses to the MOSFET gate is provided by the dsPIC30F2010 on calculating the compensator
current. Then it is fed to the gate as pulses through gate driver circuit.
Each diagonal pair conducts only for one half cycles. That is MOSFET S1 and S2 for positive half cycle and S3
and S4 for negative half cycle.
4. 110
Kalpana. K, Madhumathi. M. A & Madhumitha M
Figure 4: Voltage Source Inverter
When the MOSFET is on there is line current injecting to the source and vice versa.
We need to know the load current, line current to determine the injecting current so that it is compensated. This
current can be derived from the following equations.
5. A Hybrid Active Power Filter with Control Scheme for the Effective Compensation of Industrial Power Supply
111
The voltage equation before non linear load (ac load) is,
Vt(t) = vm1 sin (t)
The voltage and current equation after adding dc load is,
Vt(t)= vdc + vm1sin(t+φv1)+ vm2sin(2t+φv2)+ vm3sin(3t+φv3)+
iL(t)= idc +im1sin(t+φi1)+im2sin(2t+φi2)+ im3sin(3t+φi3)+
…+vmnsin(nt+φvn)
…imnsin (nt+φin)
The source power can be calculated as,
Ps = [vm1imscosφs] / 2
With that the average power can be calculated as the product of vt(t) and iL(t),
Plavg= vdcidc+ [vm1im1cosφ1] / 2+ vm2im2cosφ2] / 2+ [vm3im3cosφ3] / 2 +… [vmnimncosφn] / 2
Due to the VSI circuit the dc link capacitor acts as a load. Hence some of the power will be lost in the capacitor. It
is obtained by providing PI control loop.
Ploss= kp . ev + ki evdt
where, kp = gain of proportional controller;
ki = gain of integral controller;
error voltage, ev = vref - vact
The maximum value of source current can be calculated as,
ims = 2[Plavg+Ploss] / (vm1cosφs)
The above equation can be reduced as,
is(t) = imssin(t-φs)
With the load current and the fundamental current, the injecting current can be found out as,
ic*(t) = iL(t) – is(t)
Hence by injecting this compensator current into the line, the affected voltage regulation due to harmonic
distortion can be eliminated.
Filtering is the most common signal conditioning function, as usually mot all the signal frequency spectrum
contains valid data. The common example is 50 Hz AC power line, present in most environments, which will produce
noise if amplified. As we are using non linear loads that is both ac and dc loads the load current will be distorted. This in
turn affects the supply voltage. This will end by providing multiple zero crossings at the voltage waveforms. So in order to
find the accurate amount of magnitude of filter current and its phase angle, we need to know whether the current is lagging
or leading. For that we go for synchronous circuit. It does consist of two low pass filter circuits; all pass filters and a z ero
crossing circuit.
The microcontroller dsPIC30F2010 is used for the computation of filter current and control of the active power
filter. The processor has 40MHz clock frequency with an inbuilt analog to digital converter. The ADC is of 10 bit with an
input voltage level 0-3V.
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Kalpana. K, Madhumathi. M. A & Madhumitha M
The analogue to digital converter of the dsPIC30F2010 accepts only the signal in the range of 0-3V. Hence, the
bipolar ±5V output of the sensors is processed to the required voltage level using the signal conditioning circuit.
The circuit consists of three stages, those are
Attenuator
Summer
Precision rectifier
An attenuator has an attenuation ration of 0.3. Therefore, output of first amplifier is within the range of ±1.5 V.
A level shifter is used to shift the signal such that the output is always a uni-polar signal. In the second stage, the
bipolar signal of ±1.5 V is shifted by +1.5 V. Thus, the output of second stage amplifier is 0-3 V. The reference of -1.5 V is
generated using an adjustable negative voltage regulator (LM337) the input to this regulator is -15 V, which is drawn from
the supply of OPAMPs (±15 V).
The final stage uses a precision rectifier and a zener diode. The precision rectifier block any negative voltage and
zener is used to clip any voltage higher than 3.3V. Hence the output signal obtained after the signal conditioning circuit is
always a uni-polar signal of value 0-3V which is compatible with the ADC of dsPIC30F2010.
The output from the signal conditioning circuit is fed to the dsPIC micro controller with which the controller will
calculate the compensator current.
Thus the injecting current is calculated and the VSI is triggered in such a way to compensate the harmonic
current.
EXPERIMENTAL RESULTS
Input Current
The input current is sinusoidal waveforms with much less distortion.
Figure 5: Input Current
Output Current (Uncompensated)
The output current will be sinusoidal with more harmonics.
7. A Hybrid Active Power Filter with Control Scheme for the Effective Compensation of Industrial Power Supply
113
Figure 6: Uncompensated Output Current
Input Voltage
The input voltage as shown below is a sinusoidal waveform.
Figure 7: Input Voltage
Compensated Current From Passive Filter
The passive filter give the output with much limited harmonics.but it is not a pure sine waveform.
Figure 8: Compensated Current Output from the Passive Filter
Compensated Current From Hybrid Active Power Filter
The combination of passive filter with the shunt active power filter will produce the compensated current (shown
in light shade figure.) and the dark shade shows the output from the HAPF.
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Figure 9: Compensated Current Output from the HAPF
CONCLUSIONS
The HAPF is considered effectual means for harmonics restraint and reactive power compensation in the high
capacity power filter. In this paper, based on the filtering principle and parameters, the simulation model is established by
MATLAB/Simulink. The simulation conclusion can prove the better performance of the HAPF topology and the control
method.
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