What is islanding ?
Consider the power network as shown in fig.1
Now if we disconnect the line AB from the infinite transmission grid there will be an isolated region . The D1, D2 are power sources (eg : inverter , solar power cells ). The power generated in this region is fed to the island only.
We see that there no longer is any control over the island voltage at the bus X . Also there is no mechanism here for control of frequency.
This state is referred to as islanding.
What is islanding ?
Consider the power network as shown in fig.1
Now if we disconnect the line AB from the infinite transmission grid there will be an isolated region . The D1, D2 are power sources (eg : inverter , solar power cells ). The power generated in this region is fed to the island only.
We see that there no longer is any control over the island voltage at the bus X . Also there is no mechanism here for control of frequency.
This state is referred to as islanding.
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.
Classification Of Power System StabilityAravind Shaji
The Slide Deals With Power System Stability. Contents Include
Power System Stability Overview
Power System Stability: A Proposed Definition
Need of Stability Classification
Classification of stability
Power System Stability Classification
Rotor Angle Stability
Voltage Stability
Frequency Stability
Rotor Angle Stability vs. Voltage Stability
References
Introduction to reactive power control in electrical powerDr.Raja R
Introduction to reactive power control in electrical power
Reactive power in transmission line :
Reactive power control
Reactive power and its importance
Apparent Power
Reactive Power
Apparent Power
Reactive Power Formula
##CONTENT##
Introduction
Voltage control
Power system control
Control of reactive power and power factor
Interconnected control and frequency ties
Supervisory control
Line compensation
Series compensation
Series and shunt compensation schemes for ac transmission system
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.
discusses about the reduction of commutation torque ripple in BLDC motor and various convention methods and the proposed method for 2 level inverter and 3 level inverter
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.
Classification Of Power System StabilityAravind Shaji
The Slide Deals With Power System Stability. Contents Include
Power System Stability Overview
Power System Stability: A Proposed Definition
Need of Stability Classification
Classification of stability
Power System Stability Classification
Rotor Angle Stability
Voltage Stability
Frequency Stability
Rotor Angle Stability vs. Voltage Stability
References
Introduction to reactive power control in electrical powerDr.Raja R
Introduction to reactive power control in electrical power
Reactive power in transmission line :
Reactive power control
Reactive power and its importance
Apparent Power
Reactive Power
Apparent Power
Reactive Power Formula
##CONTENT##
Introduction
Voltage control
Power system control
Control of reactive power and power factor
Interconnected control and frequency ties
Supervisory control
Line compensation
Series compensation
Series and shunt compensation schemes for ac transmission system
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.
discusses about the reduction of commutation torque ripple in BLDC motor and various convention methods and the proposed method for 2 level inverter and 3 level inverter
Simulation of 3-phase matrix converter using space vector modulationIJECEIAES
This paper illustrates the simulation of 3-phase matrix converter using Space Vector Modulation (SVM). Variable AC output voltage engendered using matrix converter with bidirectional power switches controlled by appropriate switching pulse. The conventional PWM converter engenders switching common mode voltage across the load system terminals, which cause to common mode current and its leads to bearing failure in load drive. These problems can be rectified using SVM and which minimize the effect on the harmonic fluctuation in AC output voltage and stress on the power switch is reduced using bidirectional switch for proposed 3-phase matrix converter. The simulation results have been presented to validate the proposed system using matlab / simulink.
Evolve the Controller for Static Synchronous Series Compensator Based on Cont...IJPEDS-IAES
Real and Reactive power flow in an alternating current transmission line can be independently controlled by connecting, to the transmission line, a series- compensating voltage, which is variable in magnitude and phase angle. The Static Synchronous Series Compensator (SSSC), a solid-state voltage source inverter (VSC) coupled with a transformer, is connected in series with a transmission line. An SSSC injects an almost sinusoidal voltage, of variable magnitude, in series with a transmission line. This injected voltage is almost in quadrature with the line current, thereby emulating an inductive or a capacitive reactance in series with the transmission line. This emulated variable reactance, inserted by the injected voltage source, influences the electric power flow in the transmission line. In this report, an attempt is made to evolve the model of SSSC and VSC with preliminary studies for the controller design.
A Novel Control Strategy of Indirect Matrix Converter Using Space Vector Modu...IJPEDS-IAES
This paper introduces a control scheme of Indirect Matrix Converter which includes space vector modulation to stabilize the frequency variations. The terminal voltage and frequency of any synchronous machine can be controlled easily with this scheme. Further the control strategy is proposed and implemented in Matlab/Simulink Embedded system which gives significant better performance compared to conventional control technique like better Total Harmonic Distortion (THD), more output voltage with same Modulation Index, less switching stress and less switching loss. This method might prove effective for wind energy conversion system using DFIG as the DFIG speed is close to synchronous speed. The complete control strategy is verified using MATLAB/Simulink.
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.
SOLID STATE TRANSFORMER - USING FLYBACK CONVERTERAbhin Mohan
FUTURISTIC ELECTRICAL ENGINEERING PROJECT.
A Device that can step up as well as step down coltage and get output as both DC or AC. Total flexibility of Power using DC link by Flyback Coverter.
A survey on Single Phase to Three Phase Cyclo-Converter fed Induction MotorIJSRD
In various application of electrical energy especially in in industrial areas there are two type of current, Direct Current and Alternating Current are used. Generally fixed voltage, constant frequency Single-Phase or Three-Phase AC is easily available, yet for different applications various types of magnitudes and/or frequencies are essential. This paper presents a survey on 1-̉ۢ to 3-̉ۢ cycloconverter technique using thyristor with 3-̉ۢ induction motor along load frequency analysis. The cycloconverter is inspected in its utmost straight forward form without further output filters or elaborate control technique.
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
Performance of PWM Rectifier with Different Types of Loadijsrd.com
The paper presents the decoupled vector control of the PWM rectifier with the nonlinear DC-link voltage regulation and the load compensating feed forward. The concept of the proposed control system is based on Voltage Oriented Control with Space-Vector Pulse Width Modulation (SV-PWM). For the high-performance operation of the PWM rectifier and the satisfactory current tracing the decoupled current control has been introduced. The performance of the linear PI controller of the DC-link voltage is strictly dependent on its settings and it may introduce a disadvantageous voltage overshoot under a heavy load impact. In order to improve the transient response of the DC-link voltage control loop a load compensation has been proposed. The different approach to the control of the DC-link voltage based on the regulation of the square power of the DC voltage has been introduced.
Fuzzy logic Control & Minimizing Commutation Torque Ripple for Brushless DC M...Editor IJMTER
Brushless dc motor still suffers from commutation torque ripple, which mainly depends
on speed and transient line current in the commutation interval. This paper presents a novel circuit
topology and a dc link voltage control strategy to keep incoming and outgoing phase currents
changing at the same rate during commutation. A dc–dc single-ended primary inductor converter
(SEPIC) and a switch selection circuit are employed in front of the inverter. The desired
commutation voltage is accomplished by the SEPIC converter. The dc link voltage control strategy is
carried out by the switch selection circuit to separate two procedures, adjusting the SEPIC converter
and regulating speed. The cause of commutation ripple is analyzed, and the way to obtain the desired
dc link voltage is introduced in detail. Finally, simulation and experimental results show that,
compared with the dc–dc converter, the proposed method can obtain the desired voltage much faster
and minimize commutation torque ripple more efficiently at both high and low speeds and the closed
loop control is achieved by Fuzzy logic control.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Basic Configurations of Thyristor Controlled Phase Shifting Transformer or Phase angle Regulators
1. Flexible AC Transmission System (FACTS)
Todays Topic
Unit-2 –Description & Characteristics of Voltage Source Converter Based
FACTS Controller
Presented by
Sushovan Roy
Assistant Professor
Dream Institute of Technology, Kolkata-700104
Department of Electrical Engineering (EE)
2. Table of Contents
▪ Introduction to Phase Shifting Transformer (PST)
▪ Basic Operating Principle of Phase Shifting Transformer (PST) or Thyristor Controlled Phase angle Regulator (TCPAR)
▪ Basic Configurations of Phase Shifting Transformer (PST)
▪ Applications of Phase Shifting Transformer (PST)
▪ Advantages & Drawbacks of Phase Shifting Transformer (PST)
▪ Conclusions
3. Phase Shifting Transformer (PST)
▪ A phase shifting Transformer (PST) is another name is Thyristor Controlled Phase angle Regulator (TCPAR) or Thyristor Controlled
Phase shifting Transformer (TCPST)
▪ It is defined as the “A phase-shifting transformer adjusted by thyristor switches to provide a rapidly variable phase angle”. In general,
phase shifting is obtained by adding a perpendicular voltage vector in series with a phase. This vector is derived from the other two
phases via shunt connected transformers”
▪ The basic concept of phase angle regulation is the addition of an appropriate in-phase or a quadrature component to the prevailing terminal
(bus) voltage in order to change (increase or decrease) its magnitude or angle to the value specified (or desired).
Fig:1 Concept and basic implementation of a Phase Angle Regulator(PAR)
4. Phase Shifting Transformer (PST) Continued
▪ voltage regulation could, theoretically, be achieved by a synchronous, in-phase voltage source with controllable amplitude, in series with the
ac system and the regulated terminal In a similar manner, the arrangement of Figure can be used for phase angle control simply by
stipulating the injected voltage, to have a phase of ±90° relative to the system voltage, u, as illustrated in Figure 1
▪ A possible arrangement for phase angle regulator (PAR) is shown schematically in Figure 1 with the corresponding phasor diagram in
Figure For relatively small angular adjustments, the resultant angular change is approximately proportional to the injected voltage, while
the voltage magnitude remains almost constant.
▪ However, for large angular adjustments, the magnitude of the system voltage will appreciably increase and, for this reason, is often referred
to as a quadrature booster transformer (QBT) .
▪ The voltage magnitude could be maintained independent of the angular adjustment by a more complex winding arrangement. Nevertheless,
because of its relative simplicity, the QBT arrangement has typically been used in conventional phase shifting applications.
6. Pictorial Representation of Phase Shifting Transformer (PST)
Fig:2 Thyristor-Controlled Phase-Shifting Transformer (TCPST) or Thyristor- Controlled
Phase Angle Regulator (TCPR)
7. Performance of PST in the Transmission line
▪ The optimal loading of transmission lines in practical power systems cannot always be achieved at the prevailing transmission angle. Such
cases would occur for example, when power between two buses is transmitted over parallel lines of different electrical length or when two
buses are inserted whose prevailing angle difference is insufficient to establish the desired power flow.
▪ The basic concept of power flow control by angle regulation, illustrated in Fig.3, is represented in terms of the usual two-machine model in
which a Phase Angle Regulator is inserted between the sending-end generator (bus) and the transmission line. Theoretically, the Phase
Angle Regulator can be considered a sinusoidal (fundamental frequency) ac voltage source with controllable amplitude and phase angle.
▪ With the phase-angle control arrangement is the effective phase angle between the sending and receiving-end voltages becomes and with
this the transmitted power P and the reactive power demands at the ends of the line.
Fig:3 Two-machine power system with a Phase Angle Regulator, corresponding phasor diagram and
transmitted power vs. angle characteristics
8. Classification of Phase Shifting Transformer (PST)
The classification of the phase-shifting transformer can be done based on the characteristics like the following,
▪ Direct Phase Shifting Transformer (PSTs)
The direct PSTs or direct phase-shifting transformers mainly depend on the three-phase core and its phase shift can be obtained by connecting the
windings within a suitable way
▪ Indirect Phase Shifting Transformer (PSTs)
The indirect PSTs or indirect phase-shifting transformers mainly depend on a design using two separate transformers like variable tap exciter and
another one is the series transformer. So, variable tap exciter is used to change the quadrature voltage’s amplitude whereas the series transformer
is used to insert quadrature voltage within the correct phase.
▪ Asymmetrical Phase Shifting Transformer (PSTs)
Asymmetrical phase-shifting transformers are used to generate an output voltage through changed amplitude as well as phase angle as compared
to the input voltage.
▪ Symmetrical Phase Shifting Transformer (PSTs)
Symmetrical phase-shifting transformers generate an output voltage through a changed phase angle as compared to the input voltage, however
with a similar amplitude.
10. Basic Operating Principle of Phase Shifting Transformer (PST)
▪ By applying power electronic controllers the operation of PSTs can be made fast which enables dynamic regulation of power flow and
improvement of system stability and dynamic security. These are called Static Phase Shifting Transformers (SPST) or Thyristor Controlled
Phase Angle Regulator (TCPAR) as thyristor devices have been primarily suggested to achieve the objective. However, with the advent of
Voltage Source Converter (VSC) based FACTS controllers it is also possible to apply a UPFC type device for SPST.
Fig:4 Phase Shifting Transformer(PST)
connected in a network Fig:5 The equivalent circuit referred to
primary of PST
11. Basic Operating Principle of Phase Shifting Transformer (PST)
Fig:6 representation for Phase Shifting
Transformer (PST)
Fig:7 Schematic diagram of a Static Phase Shifting
Transformer (SPST)or TCPAR
12. Basic Configurations of Phase Shifting Transformer (PST)
▪ we will consider here only 3 configurations given below for forming Thyristor Controlled Phase Angle Regulator
(1) Point-on-wave controlled phase angle regulator
(2) Discrete step controlled phase angle regulator
(3) Using voltage source converter (VSC)
(1) Point-on-wave controlled phase angle regulator (PAR)
▪ For configuration-1, a single secondary winding (per phase) of the excitation transformer (ET) is adequate as the control of the phase angle is
provided by controlling the firing (delay) angle of the thyristor switch in relation to the applied voltage.
▪ The switches T1 and T2 are used for injecting the series voltage with positives polarity (boost), whereas T3 and T4 are used to inject the
series voltage with negative or reverse polarity (buck).
▪ Thus, the phase shift of positive or negative angle can be achieved. If switches T1 and T4 (or T2 and T3) conduct, the output voltage remains
zero
13. Basic Configurations of Phase Shifting Transformer (PST)
(2) Discrete step controlled phase angle regulator
▪ For configuration 2 with discrete control, the conduction angle of the thyristor switches is maximum at 180°. The advantage is
that the harmonic generation is eliminated. On the other hand, several secondary windings have to be provided on E.T. to have
discrete control of the phase angle. With three secondary windings whose voltages (number of turns) are in the ratios of 1:3:9,
it is possible to have 13 steps for each polarity. This requires a converter in one phase to have 3 sub-converters (each connected
to its individual winding) connected in series. Note that the voltage ratings of the thyristor valves (made up of series connection
of thyristor pairs connected back to back) in converter C3 and C9 are three times and nine times respectively, the voltage rating
of valves in converter C1
Fig:8 Simplified single phase representation of a discrete step SPST
14. Basic Configurations of Phase Shifting Transformer (PST)
(3) Using voltage source converter (VSC)
▪ For configuration 3, The converter shown in Fig.9 can be made up of two, three phase Voltage Source Converters (VSC) connected to each
other on the DC side as shown in Fig. 10. The equivalent circuits of this type of SPST is shown in Fig.11.
▪ Neglecting losses in the SPST (made up of the excitation and boost transformers, VSC1 and VSC2 and the DC capacitor), the power balance
in the DC side requires. Actually, the SPST configuration shown in Fig. 9 is a special case of the Unified Power Flow Controller where the
series voltage injected is controlled according to Eq. to provides variable phase shift within the limitations of its rating.
Fig:10 Equivalent circuit of a VSC based
SPST
Fig:9 A single line diagram of VSC based
SPST
15. Applications of Phase Shifting Transformer (PST)
There are different techniques of applications of Static Phase Shifting Transformer(SPST) or Thyristor Controlled Phase
angle Regulator (TCPAR) they are as follows
1.) Improvement of Transient Stability Using SPST
This will be illustrated using a Single Machine connected to an Infinite Bus (SMIB) system and from equal area criterion.
Fig:11 A SMIB system with
SPST
Fig:12 Power angle characteristics of a SMIB system
Fig:13 Power angle
characteristics with the
controlled SPST
16. Applications of Phase Shifting Transformer (PST)
2.) Damping of Low Frequency Power Oscillations
▪ The problem of low frequency oscillations involving rotor swings is an old one, observed for the first time in the 1960s after
the introduction of the fast acting exciters and electronic AVRs (Automatic Voltage Regulator).
▪ With the advent of the power electronic controllers such as HVDC converters and SVC, an auxiliary damping controller
could be easily implemented as a Supplementary Modulation Controller (SMC) to the power or voltage scheduling controller.
▪ Generally, damping controllers for low frequency (0.2 to 2.0 Hz) oscillations can destabilize sub synchronous frequency (10-
50 Hz) oscillations due to the torsional modes. Generally, an AVR enhances synchronizing torque, but can reduce damping
torque in stressed conditions (involving maximum power transfer and weak transmission network). By designing a SMC for
the SPST based on the rotor speed signal, it is possible to enhance the damping torque and stabilize the swing mode The
SMC is expected to act only during dynamic conditions involving oscillations.
17. Applications of Phase Shifting Transformer (PST)
▪ some applications of SPST were considered for enhancing the transfer capability of AC ties (interconnecting two systems) they have not been
implemented, An interesting new technology introduced recently is the Variable Frequency Transformer (VFT) developed by General
Electric (U.S.A) to transfer power between two asynchronous networks. The first installation of this new technology is located at Langlois
substation, interconnecting the New York (USA) and the Hydro-Quebec (Canada) system. The technology is based on a rotary transformer
(continuously variable phase-shifting transformer) with three phase windings on both rotor and stator.
▪ A drive system adjusts the VFT rotor in order to control the phase shift between the networks through the action of a fast power
controller. The first installation at Langlois controls power transfer up to 100 MW in both directions. The development of VFT shows that a
360° PST is feasible with a rotary device which is essentially based on old technology. However, the control and drive system for VFT are
based on modern technology. It is to be noted that by regulating torque applied to the rotor, through a motor drive system, the power transfer
through the VFT is controlled. The rotor will rotate continuously if the two grids operate at different frequencies. Incidentally, the principle
of phase shifting transformer can also be applied to in-phase regulators for controlling the voltage magnitude. For example, the boost
transformer is used to inject a voltage in phase with the line voltage (which can be in positive or negative direction). Alternately, thyristor
switched tap changers are used to vary the turns ratio and control the magnitude of the secondary voltage.
18. Advantages Drawbacks &Applications of TCPST or TCPAR
The advantages of phase-shifting transformers include the following.
1.) The phase shift transformer allows the operator of the grid to manage loop flows that occur suddenly, so these transformers are utilized for
congestion relief.
2.) These transformers manage power flow among two grids and they cannot enhance the capability of the lines, however, if some lines are
overloaded when capacity is still obtainable on others which are parallel to them, then optimizing the flow of power these transformers can
enhance the overall capacity of the power grid.
3.) These transformers are frequently the most economic as well as consistent approach for power supply management & system design
allowing the operators of the transmission systems to acquire more out of their accessible assets.
4.) The transmission lines which exist can be loaded up toward the thermal edge without being overloaded. So, the investment within new lines
can be postponed.
The main drawbacks of phase-shifting transformers include the following
1.) the phase shifting transformer is experienced to all overvoltage and through faults,
2.) It has Higher cost & Increased size & height