Nagesh Prabhu - Academia.edu (original) (raw)
Papers by Nagesh Prabhu
Lecture notes in electrical engineering, Nov 14, 2023
IEEE Conference Proceedings, 2016
International Journal of Power Electronics and Drive Systems, 2017
One of the advanced power applications using energy storage is the integration of energy storage ... more One of the advanced power applications using energy storage is the integration of energy storage technologies with VSC-based FACTS controllers. With the support of energy storage device, FACTS controllers will have the ability to exchange active power or energy with the ac network in steady state. This paper discusses the impact of Static Synchronous Compensator incorporating energy storage device (STATCOM-ES) on subsynchronous resonance (SSR). It also proposes the design of an auxiliary SSR damping controller (SSDC) for STATCOM-ES to damp the subsynchronous oscillations which the system is undergoing because of a series capacitor in the transmission system. The system under consideration is IEEE FBM which is modified to incorporate STATCOM-ES at the electrical midpoint. The investigation of SSR characteristics when a STATCOM - ES operating in bus voltage regulation mode is carried out by eigenvalue and damping torque analysis. Transient analysis based on the nonlinear model is also...
2019 Fifth International Conference on Electrical Energy Systems (ICEES), 2019
The application of Fuel Cell Interfaced Distribution STATic COMpensator (DSTATCOM) for active and... more The application of Fuel Cell Interfaced Distribution STATic COMpensator (DSTATCOM) for active and reactive power interaction along with harmonic elimination has been discussed in this paper. The energy interfaced DSTATCOM can be used for (i) Harmonic Elimination, (ii) Load Balancing, (iii)Reactive Power Compensation and (iv) Active Power supportduring peak load period. This paper investigates the effectiveness of performance of Fuel Cell interfaced DSTATCOM and analyses the effectiveness of control law and controllers for Power Quality enhancement. The electrical equivalent model is integrated with the DSTATCOM to study the capability to absorb /supply active power at the DC bus. The control scheme for fuel cell interfaced DSTATCOM is developed to produce the reference mathrmcurrentsifxast\mathrm{currentsi_{fx}^{\ast}}mathrmcurrentsifxast for the current controlled Voltage Source Converter (VSC), which will inject current at the Point of Common Coupling (PCC)to eliminate harmonics and maintain the PCC voltage while supplying a part of active power demanded by the load. This ensures the source current to be balanced and single frequency. The transient simulationis performed on anelaborated nonlinear model of DSTATCOM/Fuel Cell system using MATLAB-SIMULINK toolto validate the satisfactory response of DSTATCOM.
Abstract—In this paper, investigation of subsynchronous resonance (SSR) characteristics of a hybr... more Abstract—In this paper, investigation of subsynchronous resonance (SSR) characteristics of a hybrid series compensated system and the design of voltage controller for three level 24-pulse Voltage Source Converter based Static Synchronous Series Compensator (SSSC) is presented. Hybrid compensation consists of series fixed capacitor and SSSC which is a active series FACTS controller. The design of voltage controller for SSSC is based on damping torque analysis, and Genetic Algorithm (GA) is adopted for tuning the controller parameters. The SSR Characteristics of SSSC with constant reactive voltage control modes has been investigated. The results show that the constant reactive voltage control of SSSC has the effect of reducing the electrical resonance frequency, which detunes the SSR.The analysis of SSR with SSSC is carried out based on frequency domain method, eigenvalue analysis and transient simulation. While the eigenvalue and damping torque analysis are based on D-Q model of SSSC...
Intelligent Renewable Energy Systems
In this 21st century smart grids are considered as one of the most efficient ways of transmission... more In this 21st century smart grids are considered as one of the most efficient ways of transmission of electricity. Electric spring is one of the elements in smart grid technology which improves the power quality and reliability of the power grid. The system consists of parallel operation of Non-critical loads with Critical load that are sensitive to voltage fluctuations. The voltage of Critical load should be maintained constant. The Non critical load is connected in series with the Electric spring to form a smart load. This paper presents the operation of Electric spring as a smart device to enhance the voltage regulation while achieving the load power demand compensation leading to better demand side management.
International Journal of Electrical Power & Energy Systems, 2014
Abstract The Voltage Source Converter based HVDC provides asynchronous interconnection between tw... more Abstract The Voltage Source Converter based HVDC provides asynchronous interconnection between two AC systems. The use of VSC HVDC enables independent control of real and reactive power. Unlike conventional HVDC, the VSC HVDC does not cause Subsynchronous Resonance (SSR) when it is close to turbo-generators. The system strength of long ac transmission line can be enhanced by providing series compensation. However, there is a possibility of SSR interaction with turbine-generator due to the presence of the series capacitor in transmission line and may lead to shaft failure of the turbine-generator. The objective of this paper is to analyze the damping of subsynchronous resonance when the series compensated long AC line and VSC HVDC are originated from the same substation. A simple method for the extraction of subsynchronous component of line current using filter is proposed. The extracted subsynchronous frequency current is injected by the VSC HVDC converter close to the turbine-generator. This suppresses the subsynchronous current flowing through the generator and increases the damping of the system at critical torsional frequencies. This technique is termed as Subsynchronous Current Injection (SSCI). Subsynchronous current injector is designed using D–Q model of VSC HVDC. Genetic Algorithm (GA) is used for tuning the converter controllers and filter parameters. The results show the effectiveness of the proposed subsynchronous current injector in damping of SSR.
The development of power semiconductors, specially IGBTs has led to the small power HVDC transmis... more The development of power semiconductors, specially IGBTs has led to the small power HVDC transmission based on voltage source converters (VSCs). The VSC based HVDC transmission system mainly consists of two converter stations connected by a dc cable. This paper presents the modelling and control design of VSC based HVDC which uses twelve pulse three level converter topology. The reactive current injected by individual VSCs can be maintained constant or controlled to regulate converter bus voltage constant. While one VSC regulates the dc bus voltage the other controls the power flow in the dc link. Each VSC can have up to 4 controllers depending on the operating mode. The controller structure adopted for power controller is of PID type and all other controllers are of PI type. Each operating mode requires proper tuning of controller gains in order to achieve satisfactory system performance. This paper discusses a systematic approach for parameter optimization in selecting controller ...
A STATic synchronous COMpensator (STATCOM) is a shunt connected voltage source converter (VSC) ba... more A STATic synchronous COMpensator (STATCOM) is a shunt connected voltage source converter (VSC) based FACTS controller using Gate Turn Off (GTO) power semiconductor devices employed for reactive power control. The operation principal is similar to that of a synchronous condenser. A typical application of a STATCOM is voltage regulation at the midpoint of a long transmission line for the enhancement of power transfer capability and/or reactive power control at the load centre. This paper presents the modeling of STATCOM with twenty four pulse three level VSC and Type-1 controller to regulate the reactive current or the bus voltage. The performance is evaluated by transient simulation. It is observed that, the STATCOM shows excellent transient response to step change in the reactive current reference. While the eigenvalue analysis is based on D-Q model, the transient simulation is based on both D-Q and 3 phase models of STATCOM (which considers switching action of VSC).
Introduction: Power Generation and Transmission is a complex process, requiring the working of ma... more Introduction: Power Generation and Transmission is a complex process, requiring the working of many components of the power system in tandem. One of the major considerations is to ensure voltage magnitude at the prescribed levels at all the buses in a power transmission network. It is required to maintain the voltage to deliver the active power through the lines. To improve the performance of AC power systems, we need to compensate for the reactive power at load centres in view of minimising the reactive power flow in the transmission network, to reduce the transmission loses. Reactive Power can best be described as the quantity of “unused” power that is developed by reactive components, such as inductors or capacitors in an AC circuit or system. It is a widely accepted idea that instead of depending on the Power system to meet the reactive power demand of the power system components, it is better if dedicated reactive power compensators are used to meet the local reactive power dem...
International Journal of Electrical and Computer Engineering, 2011
263 Abstract—In this paper, investigation of subsynchronous resonance (SSR) characteristics of a ... more 263 Abstract—In this paper, investigation of subsynchronous resonance (SSR) characteristics of a hybrid series compensated system and the design of voltage controller for three level 24-pulse Voltage Source Converter based Static Synchronous Series Compensator (SSSC) is presented. Hybrid compensation consists of series fixed capacitor and SSSC which is a active series FACTS controller. The design of voltage controller for SSSC is based on damping torque analysis, and Genetic Algorithm (GA) is adopted for tuning the controller parameters. The SSR Characteristics of SSSC with constant reactive voltage control modes has been investigated. The results show that the constant reactive voltage control of SSSC has the effect of reducing the electrical resonance frequency, which detunes the SSR.The analysis of SSR with SSSC is carried out based on frequency domain method, eigenvalue analysis and transient simulation. While the eigenvalue and damping torque analysis are based on D-Q model of ...
This paper investigates the impact of static synchronous series compensator with energy storage (... more This paper investigates the impact of static synchronous series compensator with energy storage (SSSC-ES) Hopf bifurcations of Subsynchronous resonance (SSR). The effect of injecting real and reactive voltage by SSSC-ES on SSR is investigated using bifurcation analysis. The IEEE first benchmark model with static exciter and power system stabilizer is considered for the analysis. The results obtained are validated by eigenvalue analysis and transient simulation. The effect of adding SSSC-ES into the power system on the stability boundary is analyzed.
Low frequency oscillations(LFO) in power system are caused due to various anomalies which can res... more Low frequency oscillations(LFO) in power system are caused due to various anomalies which can result in instability and can lead to blackout. This paper presents the refined Prony analysis to optimally locate Supplementary damping controller(SDC) for damping LFO in a high power penetrating Power systems. The proposed method is applied to the active power signals measured with the Wide Area Measurement System(WAMS) for Multimachine Power system. The refined Prony method is vigorous to sampling rate and a better tool to ensure proper activation of SDC in real time control of power systems to ensure dynamic stability and secured system operation.
The STATic synchronous COMpensator (STATCOM) is a voltage source converter (VSC) based FACTS cont... more The STATic synchronous COMpensator (STATCOM) is a voltage source converter (VSC) based FACTS controller. It is a shunt connected FACTS controller and most suitable in long transmission line for regulating voltage, improving stability and enhancing power transfer capability. STATCOM with PI controller based reactive current control experiences oscillatory instability in inductive mode. The incorporation of nonlinear state variable feedback with PI controller can overcome the oscillatory instability predicted in the inductive operation mode of STATCOM. However, the response or performance of the STATCOM depends primarily on the parameters of controller. This paper presents optimization of controller parameters based on Genetic Algorithm (GA) and Particle Swarm Optimization (PSO), and the results are compared. The performance of the designed controller is evaluated by transient simulation. The two methods have good ability in searching global optimum, and it is observed that GA outperf...
Lecture notes in electrical engineering, Nov 14, 2023
IEEE Conference Proceedings, 2016
International Journal of Power Electronics and Drive Systems, 2017
One of the advanced power applications using energy storage is the integration of energy storage ... more One of the advanced power applications using energy storage is the integration of energy storage technologies with VSC-based FACTS controllers. With the support of energy storage device, FACTS controllers will have the ability to exchange active power or energy with the ac network in steady state. This paper discusses the impact of Static Synchronous Compensator incorporating energy storage device (STATCOM-ES) on subsynchronous resonance (SSR). It also proposes the design of an auxiliary SSR damping controller (SSDC) for STATCOM-ES to damp the subsynchronous oscillations which the system is undergoing because of a series capacitor in the transmission system. The system under consideration is IEEE FBM which is modified to incorporate STATCOM-ES at the electrical midpoint. The investigation of SSR characteristics when a STATCOM - ES operating in bus voltage regulation mode is carried out by eigenvalue and damping torque analysis. Transient analysis based on the nonlinear model is also...
2019 Fifth International Conference on Electrical Energy Systems (ICEES), 2019
The application of Fuel Cell Interfaced Distribution STATic COMpensator (DSTATCOM) for active and... more The application of Fuel Cell Interfaced Distribution STATic COMpensator (DSTATCOM) for active and reactive power interaction along with harmonic elimination has been discussed in this paper. The energy interfaced DSTATCOM can be used for (i) Harmonic Elimination, (ii) Load Balancing, (iii)Reactive Power Compensation and (iv) Active Power supportduring peak load period. This paper investigates the effectiveness of performance of Fuel Cell interfaced DSTATCOM and analyses the effectiveness of control law and controllers for Power Quality enhancement. The electrical equivalent model is integrated with the DSTATCOM to study the capability to absorb /supply active power at the DC bus. The control scheme for fuel cell interfaced DSTATCOM is developed to produce the reference mathrmcurrentsifxast\mathrm{currentsi_{fx}^{\ast}}mathrmcurrentsifxast for the current controlled Voltage Source Converter (VSC), which will inject current at the Point of Common Coupling (PCC)to eliminate harmonics and maintain the PCC voltage while supplying a part of active power demanded by the load. This ensures the source current to be balanced and single frequency. The transient simulationis performed on anelaborated nonlinear model of DSTATCOM/Fuel Cell system using MATLAB-SIMULINK toolto validate the satisfactory response of DSTATCOM.
Abstract—In this paper, investigation of subsynchronous resonance (SSR) characteristics of a hybr... more Abstract—In this paper, investigation of subsynchronous resonance (SSR) characteristics of a hybrid series compensated system and the design of voltage controller for three level 24-pulse Voltage Source Converter based Static Synchronous Series Compensator (SSSC) is presented. Hybrid compensation consists of series fixed capacitor and SSSC which is a active series FACTS controller. The design of voltage controller for SSSC is based on damping torque analysis, and Genetic Algorithm (GA) is adopted for tuning the controller parameters. The SSR Characteristics of SSSC with constant reactive voltage control modes has been investigated. The results show that the constant reactive voltage control of SSSC has the effect of reducing the electrical resonance frequency, which detunes the SSR.The analysis of SSR with SSSC is carried out based on frequency domain method, eigenvalue analysis and transient simulation. While the eigenvalue and damping torque analysis are based on D-Q model of SSSC...
Intelligent Renewable Energy Systems
In this 21st century smart grids are considered as one of the most efficient ways of transmission... more In this 21st century smart grids are considered as one of the most efficient ways of transmission of electricity. Electric spring is one of the elements in smart grid technology which improves the power quality and reliability of the power grid. The system consists of parallel operation of Non-critical loads with Critical load that are sensitive to voltage fluctuations. The voltage of Critical load should be maintained constant. The Non critical load is connected in series with the Electric spring to form a smart load. This paper presents the operation of Electric spring as a smart device to enhance the voltage regulation while achieving the load power demand compensation leading to better demand side management.
International Journal of Electrical Power & Energy Systems, 2014
Abstract The Voltage Source Converter based HVDC provides asynchronous interconnection between tw... more Abstract The Voltage Source Converter based HVDC provides asynchronous interconnection between two AC systems. The use of VSC HVDC enables independent control of real and reactive power. Unlike conventional HVDC, the VSC HVDC does not cause Subsynchronous Resonance (SSR) when it is close to turbo-generators. The system strength of long ac transmission line can be enhanced by providing series compensation. However, there is a possibility of SSR interaction with turbine-generator due to the presence of the series capacitor in transmission line and may lead to shaft failure of the turbine-generator. The objective of this paper is to analyze the damping of subsynchronous resonance when the series compensated long AC line and VSC HVDC are originated from the same substation. A simple method for the extraction of subsynchronous component of line current using filter is proposed. The extracted subsynchronous frequency current is injected by the VSC HVDC converter close to the turbine-generator. This suppresses the subsynchronous current flowing through the generator and increases the damping of the system at critical torsional frequencies. This technique is termed as Subsynchronous Current Injection (SSCI). Subsynchronous current injector is designed using D–Q model of VSC HVDC. Genetic Algorithm (GA) is used for tuning the converter controllers and filter parameters. The results show the effectiveness of the proposed subsynchronous current injector in damping of SSR.
The development of power semiconductors, specially IGBTs has led to the small power HVDC transmis... more The development of power semiconductors, specially IGBTs has led to the small power HVDC transmission based on voltage source converters (VSCs). The VSC based HVDC transmission system mainly consists of two converter stations connected by a dc cable. This paper presents the modelling and control design of VSC based HVDC which uses twelve pulse three level converter topology. The reactive current injected by individual VSCs can be maintained constant or controlled to regulate converter bus voltage constant. While one VSC regulates the dc bus voltage the other controls the power flow in the dc link. Each VSC can have up to 4 controllers depending on the operating mode. The controller structure adopted for power controller is of PID type and all other controllers are of PI type. Each operating mode requires proper tuning of controller gains in order to achieve satisfactory system performance. This paper discusses a systematic approach for parameter optimization in selecting controller ...
A STATic synchronous COMpensator (STATCOM) is a shunt connected voltage source converter (VSC) ba... more A STATic synchronous COMpensator (STATCOM) is a shunt connected voltage source converter (VSC) based FACTS controller using Gate Turn Off (GTO) power semiconductor devices employed for reactive power control. The operation principal is similar to that of a synchronous condenser. A typical application of a STATCOM is voltage regulation at the midpoint of a long transmission line for the enhancement of power transfer capability and/or reactive power control at the load centre. This paper presents the modeling of STATCOM with twenty four pulse three level VSC and Type-1 controller to regulate the reactive current or the bus voltage. The performance is evaluated by transient simulation. It is observed that, the STATCOM shows excellent transient response to step change in the reactive current reference. While the eigenvalue analysis is based on D-Q model, the transient simulation is based on both D-Q and 3 phase models of STATCOM (which considers switching action of VSC).
Introduction: Power Generation and Transmission is a complex process, requiring the working of ma... more Introduction: Power Generation and Transmission is a complex process, requiring the working of many components of the power system in tandem. One of the major considerations is to ensure voltage magnitude at the prescribed levels at all the buses in a power transmission network. It is required to maintain the voltage to deliver the active power through the lines. To improve the performance of AC power systems, we need to compensate for the reactive power at load centres in view of minimising the reactive power flow in the transmission network, to reduce the transmission loses. Reactive Power can best be described as the quantity of “unused” power that is developed by reactive components, such as inductors or capacitors in an AC circuit or system. It is a widely accepted idea that instead of depending on the Power system to meet the reactive power demand of the power system components, it is better if dedicated reactive power compensators are used to meet the local reactive power dem...
International Journal of Electrical and Computer Engineering, 2011
263 Abstract—In this paper, investigation of subsynchronous resonance (SSR) characteristics of a ... more 263 Abstract—In this paper, investigation of subsynchronous resonance (SSR) characteristics of a hybrid series compensated system and the design of voltage controller for three level 24-pulse Voltage Source Converter based Static Synchronous Series Compensator (SSSC) is presented. Hybrid compensation consists of series fixed capacitor and SSSC which is a active series FACTS controller. The design of voltage controller for SSSC is based on damping torque analysis, and Genetic Algorithm (GA) is adopted for tuning the controller parameters. The SSR Characteristics of SSSC with constant reactive voltage control modes has been investigated. The results show that the constant reactive voltage control of SSSC has the effect of reducing the electrical resonance frequency, which detunes the SSR.The analysis of SSR with SSSC is carried out based on frequency domain method, eigenvalue analysis and transient simulation. While the eigenvalue and damping torque analysis are based on D-Q model of ...
This paper investigates the impact of static synchronous series compensator with energy storage (... more This paper investigates the impact of static synchronous series compensator with energy storage (SSSC-ES) Hopf bifurcations of Subsynchronous resonance (SSR). The effect of injecting real and reactive voltage by SSSC-ES on SSR is investigated using bifurcation analysis. The IEEE first benchmark model with static exciter and power system stabilizer is considered for the analysis. The results obtained are validated by eigenvalue analysis and transient simulation. The effect of adding SSSC-ES into the power system on the stability boundary is analyzed.
Low frequency oscillations(LFO) in power system are caused due to various anomalies which can res... more Low frequency oscillations(LFO) in power system are caused due to various anomalies which can result in instability and can lead to blackout. This paper presents the refined Prony analysis to optimally locate Supplementary damping controller(SDC) for damping LFO in a high power penetrating Power systems. The proposed method is applied to the active power signals measured with the Wide Area Measurement System(WAMS) for Multimachine Power system. The refined Prony method is vigorous to sampling rate and a better tool to ensure proper activation of SDC in real time control of power systems to ensure dynamic stability and secured system operation.
The STATic synchronous COMpensator (STATCOM) is a voltage source converter (VSC) based FACTS cont... more The STATic synchronous COMpensator (STATCOM) is a voltage source converter (VSC) based FACTS controller. It is a shunt connected FACTS controller and most suitable in long transmission line for regulating voltage, improving stability and enhancing power transfer capability. STATCOM with PI controller based reactive current control experiences oscillatory instability in inductive mode. The incorporation of nonlinear state variable feedback with PI controller can overcome the oscillatory instability predicted in the inductive operation mode of STATCOM. However, the response or performance of the STATCOM depends primarily on the parameters of controller. This paper presents optimization of controller parameters based on Genetic Algorithm (GA) and Particle Swarm Optimization (PSO), and the results are compared. The performance of the designed controller is evaluated by transient simulation. The two methods have good ability in searching global optimum, and it is observed that GA outperf...