Thyristor Controlled Series Capacitor Controller Research Articles

TCSC Application for Transient Stabilization of Wind Turbine with Fixed Speed Induction Generator

Wind turbines (WTs) are a desirable alternative to traditional nonrenewable power resources as a result of recent environmental concerns. Some of them are fixed speed wind generator (FSWG) and have been integrated to power system by squirrel cage induction generator (SCIG). Induction machine absorbs reactive power during all operating conditions, especially at fault condition may result in severe voltage drop which can lead to generator outage. This outage disconnects a significant amount of active power and consequently leads to frequency instability. In order to prevent induction generator (IG) outages in short circuit failures, this paper investigates thyristor-controlled series capacitor (TCSC) device as a candidate solution. TCSC compensates the IG terminal voltage drop by adjusting transmission line impedance at fault condition. In the proposed method, a metaheuristic technique means that shuffled frog leaping algorithm (SFLA) has been utilized to optimize the TCSC controller gains. The proposed scheme can be applied for both SCIGs and wound rotor induction generators (WRIGs) which is another advantage of this method. Single-machine infinite bus system is considered as case study, and various operating conditions and disturbances have been considered to verify the effectiveness of the proposed method.

Three-phase fault analysis of power system transient stability based on TCSC controller using FPA for its location

Preventing the power system from becoming overloaded and under stress to the point where it is on the verge of reaching the limits of its transient stability due to high power consumption. This paper proposed the dynamic security assessment for transient stability using Thyristor controlled series capacitor (TCSC) devices controller. The stability criteria are based on the severity indices for analyzing the fault in the power system. The index uses the time domain analysis simulation, making it easier and simpler to implement for the system operators to better prepare for potential disturbances by anticipating how power systems will behave. The optimal location and parameters setting of the TCSC was determined by Flower Pollination Algorithm (FPA) due to its higher convergence rate. The proposed index is tested on the IEEE 14-bus system and further discusses the effect of a three-phase short circuit fault, different fault locations, and fault clearing method. An analysis is done to determine how the short circuit faults on lines affect the transient voltage stability of the load bus and generator bus in the system. The findings show that by employing TCSC, the voltage drop was acceptable improved and stability margins were greatly increased.

Power flow control of power systems based on a simple TCSC model

Thyristor-Controlled Series Capacitor (TCSC) is used to control the active power flow in transmission lines in the power system to specific values. This paper proposes a simple modeling of TCSC into Newton-Raphson load flow algorithm in order to reduce the complexity and enhance the reusability of the original load flow code. TCSC is represented by two injected loads at the sending and auxiliary buses. These loads are calculated based on the specified active power while the reactive power is calculated based on the systems. The reactive loads are updated during the iterative process until the convergence is achieved. TCSC parameters are calculated based on the voltages of connected buses and the specified active power. This model solves the problem associated with the selection of proper initial values of the TCSC control parameter. The proposed TCSC model is validated using the standard IEEE 14-bus, IEEE 30-bus and IEEE 118-bus test systems.

Transient Stability Assessment by Coordinated Control of SVC and TCSC with Particle Swarm Optimization

This paper aims on improving the stability of a 9 bus power system under fault condition using coordination of FACTS device. Flexible A.C. transmission system (FACTS) can be regulated reliable with faster output and can improve local power grid status with control with appropriate control strategies in very small time period. Based on that, a particle swarm optimization (PSO) algorithm was executed, to design the coordinated parameter of static VAR compensator (SVC) and Thyristor Controlled Series Capacitor (TCSC). Simulation is performed on WSCC 9-bus system in MATLAB software. When 3 phase fault is applied near to generator, frequency and rotor angle changes accordingly. With coordinated control of FACTS devices with PSO has implemented both, near to its normal condition. PSO performed in this paper was structured on identifying the values of L and C of SVC and TCSC, for superior coordination.

ABC Algorithm for Estimation of Dynamic Parameters in Radial Power System Transfer path

In this paper, the artificial bee colony algorithm (ABC) is used to predict the stability of the power system and is evaluated the aggregated machine reactance and inertias in the transfer path. The proposed method is used for estimating the dynamic parameters of the aggregated machines for each area utilising the amplitudes of voltage oscillations measured at any three intermediate points on the transfer path. Two types of voltage control equipment are considered, namely, a static var compensator (SVC) and a thyristor controlled series capacitor (TCSC) including the purpose of voltage support and reducing the disturbance in the system. The proposed methods employ bus voltage phasor data at several buses including the voltage control bus and the line currents on the power transfer path. Here, the three phase fault is applied in the power system. Based on the estimation, the dynamics of the power system is improved and the proposed strategy is utilised for improving the overall dynamic security. The proposed technique is implemented in MATLAB/simulink working platform and the output performance is evaluated and compared with the existing methods such as without facts devices, SVC based controller and genetic algorithm (GA) based TCSC controller respectively.

Robust wide-area TCSC controller for damping enhancement of inter-area oscillations in an interconnected power system with actuator saturation

Actuator saturation is an inevitable phenomenon in control system which degrades the system performance if it is not considered in the controller design. In this paper, a robust wide-area damping controller is designed for a thyristor controlled series capacitor (TCSC) to enhance the damping of inter-area oscillations when the power system is subjected to actuator saturation. A generalized sector condition is used to represent the nonlinear effects introduced by the actuator saturation in the closed-loop system. By using these conditions, the stabilization conditions for ensuring asymptotic stability of the closed-loop system are derived based on an quadratic Lyapunov criterion. The design of damping controller that maximizes the region of attraction is formulated in the form of linear matrix inequality (LMI) and solved as an optimization problem to achieve damping of inter-area oscillations. In addition to the damping controller, further, a robust pole placement approach is employed to place the closed-loop poles in a prescribed stability region. Two case studies, namely, a two-area four-machine power system and 16 machine 68 bus power system are considered to evaluate the performance of the proposed damping controller.

Design and Analysis of Gravitational Search Algorithm Based TCSC Controller in Power System

In present era, the main contact of the power segment engineers is to expand the ability and immovability of the current power segment for attractive system presentation and dependable process. This directs to the growth of FACTS technology. FACTS controllers raise power conveys ability and constancy. This article represents representing and simulation of single machine infinite bus (SMIB) system with TCSC controller. Thyristor Controlled Series Capacitor (TCSC) controller is exercised to improve transient constancy of the SMIB system. In this article propose of TCSC controller is projected. The form of SMIB with TCSC and PID controllers are expanded in MATLAB for simulation. Three phase symmetrical faults are initiated to learn its characteristics. The simulation effects confirm that the constancy of the power system is being developed by TCSC controller and it efficiently damp out the power system oscillations.

A Variable Structured TCSC Controller for Power System Stability Enhancement

In present era, the main contact of the power segment engineers is to expand the ability and immovability of the current power segment for attractive system presentation and dependable process. This directs to the growth of FACTS technology. FACTS controllers raise power convey ability and constancy. This article represents representing and simulation of single machine infinite bus (SMIB) system with TCSC controller. Thyristor Controlled Series Capacitor (TCSC) controller is exercised to improve transient constancy of the SMIB system. In this article propose of TCSC controller is projected. The form of SMIB with TCSC and PID controllers are expanded in MATLAB for simulation. Three phase symmetrical faults are initiated to learn its characteristics. The simulation effects confirm that the constancy of the power system is being developed by TCSC controller and it efficiently damp out the power system oscillations.

Fuzzy based damping controller for TCSC using local measurements to enhance transient stability of power systems

This paper proposes a local fuzzy based damping controller (LFDC) for thyristor controlled series capacitor (TCSC) to improve transient stability of power systems. In order to implement the proposed scheme, detailed model of TCSC, based on actual behavior of thyristor valves, is adopted. The LFDC uses the frequency at the TCSC bus as a local feedback signal, to control the firing angle. The parameters of fuzzy controller are tuned using an off-line method through chaotic optimization algorithm (COA). To verify the proposed LFDC, numerical simulations are carried out in Matlab/Simpower toolbox for the following case studies: two-area two-machine (TATM), WSCC three-machine nine-bus and Kundur’s two-area four-machine (TAFM) systems under various faults types. In this regard, to more evaluate the effectiveness of the proposed method, the simulation results are compared with the wide-area fuzzy based damping controller (WFDC). Moreover, the transient behavior of the detailed and phasor models of the TCSC is discussed in the TATM power system. The simulation results confirm that the proposed LFDC is an efficient tool for transient stability improvement since it utilizes only local signals, which are easily available.

Performance comparison of TCSC with TCPS and SSSC controllers in AGC of realistic interconnected multi-source power system

Abstract The primary goals of employing series flexible ac transmission system (FACTS) in automatic generation control (AGC) studies of interconnected power systems are mitigating area frequency and tie-line power oscillations. This paper compares dynamic performance of thyristor controlled series capacitor (TCSC) as damping controller with thyristor controlled phase shifter (TCPS) and static synchronous series compensator (SSSC) which are series FACTS damping controllers. Commonly used lead-lag controllers are used in structure of damping controllers. The effect of TCSC in tie-line power exchange is modeled mathematically based on the Taylor series expansion for small-signal load disturbance. The performance of the proposed TCSC controller in coordination with integral AGC is compared with cases of TCPS–AGC and SSSC–AGC. An improved particle swarm optimization (IPSO) algorithm and integral of time multiplied squared error (ITSE) performance index are used to design the damping controllers. A two-area power system having generations from reheat thermal, hydro, and gas units in each area is evaluated regarding nonlinearity effects of generation rate constraint (GRC) and governor dead band (GDB). The simulations results in MATLAB/SIMULINK environment show that the proposed TCSC–AGC yields superior performance than others in damping of area frequencies and tie-line oscillations. Furthermore, sensitivity analyses are performed to show greater robustness of TCSC–AGC.

Coordinated design of power system stabilizers and TCSC employing improved harmony search algorithm

Power System Stabilizers (PSS) are generally employed to damp electromechanical oscillations by providing auxiliary stabilizing signals to the excitation system of the generators. But it has been found that these Conventional PSS (CPSS) do not provide sufficient damping for inter-area oscillations in multi-machine power systems. Thyristor Controlled Series Capacitor (TCSC) has immense potential in damping of inter-area power swings and in mitigating the sub-synchronous resonance. In this paper Improved Harmony Search Algorithm (IHSA) has been proposed for coordinated design of multiple PSS and TCSC in order to effectively damp the oscillations. The results obtained by using IHSA on WSCC 3-machine, 9-bus system are found to be superior compared to the results obtained using Bacterial Swarm Optimization (BSO) algorithm. The damping performance of conventional PSS and TCSC controllers is also compared with coordinated design of IHSA based PSS and TCSC on New England 10-machine, 39-bus system over wide range of operating conditions and contingencies. To demonstrate the effectiveness of the proposed technique the results obtained on this test system are also compared with the results obtained with Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Harmony Search Algorithm (HSA) and Bacterial Swarm Optimization (BSO).

Perturbation estimation based coordinated adaptive passive control for multimachine power systems

This paper proposes a perturbation estimation based coordinated adaptive passive control (PECAPC) of generators excitation system and thyristor-controlled series capacitor (TCSC) devices for complex, uncertain and interconnected multimachine power systems. Discussion begins with the PECAPC design, in which the combinatorial effect of system uncertainties, unmodelled dynamics and external disturbances is aggregated into a perturbation term, and estimated online by a perturbation observer (PO). PECAPC aims to achieve a coordinated adaptive control between the excitation controller (EC) and TCSC controller based on the nonlinearly functional estimate of the perturbation. In this control scheme an explicit control Lyapunov function (CLF) and the strict assumption of linearly parametric uncertainties made on system structures can be avoided. A decentralized stabilizing EC for each generator is firstly designed. Then a coordinated TCSC controller is developed to passivize the whole system, which improves system damping through reshaping the distributed energies in power systems. Case studies are carried out on a single machine infinite bus (SMIB) and a three-machine system, respectively. Simulation results show that the PECAPC-based EC and TCSC controller can coordinate each other to improve the power system stability, finally a hardware-in-the-loop (HIL) test is carried out to verify its implementation feasibility.

Coordinated design of TCSC and PSS controllers using VURPSO and Genetic algorithms for multi-machine power system stability

Thyristor controlled series capacitor (TCSC) can regulate line impedance and therefore increase transferred power of the system. On the other hand power system stabilizer (PSS) increases dynamic stability of generator. To enhance the stability, combination of TCSC and PSS can be applied, and in such a case coordination of TCSC and PSS is essential. This paper applies this combined controller in order to enhance the stability of multi-machine system. Parameters of these controllers are optimized by velocity update relaxation particle swarm optimization (VURPSO) algorithm and Genetic algorithm (GA). The simulation results show that the combination of VURPSO algorithm and GA leads to a better design and stability.

Comparative Assessment of SVC and TCSC Controllers on the Small Signal Stability Margin of a Power System Incorporating Intermittent Wind Power Generation

Wind power is highly variable due to the stochastic behavior of wind speeds. This intermittent nature could excite the electromechanical modes resulting in the small signal instability of a power system. In this study, the performance of static VAR compensation (SVC) and thyristor controlled series capacitor (TCSC) controllers in the damping of electromechanical modes is analyzed and compared. The study employs probabilistic modal analysis method using Monte Carlo simulation and Latin hypercube sampling techniques. Various scenarios are created to get insight into the study. The results obtained from the modal analysis are verified by using the time-domain simulation. Some of the key results show that SVC is more robust in the damping of electromechanical modes compared to TCSC. The result also reveals that allocation of power system stabilizer (PSS) using probabilistic method is more effective and robust compared to deterministic approach.

Coordinated Design of PSS and TCSC Controller for Power System Damping Improvement with Multiple Control Design Requirements

In this paper an Optimization based linear control design method is used to achieve a coordinated design of Power System Stabilizer (PSS) and Thyristor Controlled Series Capacitor (TCSC) for power system damping improvement with pre specified control design requirements. The settling time is considered as main performance criteria in time domain specification and gain and phase margins for frequency domain specifications. The main objective of the coordination of controllers is to improve the global stability through damping of oscillations by improving the damping ratio of the system and minimizing the settling time of the system response. Thus coordination increases the reliability of the system and maintains the required damping even one or more controllers are out of service and hence reduces the need for additional controller. Optimization based linear control design is used to determine the optimal gain and time constant setting of lead-lag controller parameters for PSS and TCSC. The coordinated PSS and TCSC controller is tested in the Single Machine Infinite Bus Power System (SMIB). Simulation is carried out using Matlab2011b. From the time domain simulation results it is observed that oscillations are damped out, settling time is reduced and damping ratio is improved. From bode plot it is inferred that gain and phase margin of the system is further improved to satisfy the system requirements. In the overall analysis, optimization based linear control design implemented for the coordination of PSS and TCSC controller satisfies the practical requirements of the power system oscillation damping problem, also shift the eigen values to the left half of the s-plane as far as possible and hence enhances the overall system stability

An interval type-2 fuzzy logic controller for TCSC to improve the damping of power system oscillations

In this paper an interval type-2 fuzzy logic controller (IT2FLC) was proposed for thyristor controlled series capacitor (TCSC) to improve power system damping. For controller design, memberships of system variables were represented using interval type-2 fuzzy sets. The three-dimensional membership function of type-2 fuzzy sets provided additional degree of freedom that made it possible to directly model and handle uncertainties. Simulations conducted on a single machine infinite bus (SMIB) power system showed that the proposed controller was more effective than particle swarm optimization (PSO) tuned and type-1 fuzzy logic (T1FL) based damping controllers. Robust performance of the proposed controller was also validated at different operating conditions, various disturbances and parameter variation of the transmission line parameters.

Gravitational search algorithm for coordinated design of PSS and TCSC as damping controller

A newly developed heuristic global optimization algorithm, called gravitational search algorithm (GSA), was introduced and applied for simultaneously coordinated designing of power system stabilizer (PSS) and thyristor controlled series capacitor (TCSC) as a damping controller in the multi-machine power system. The coordinated design problem of PSS and TCSC controllers over a wide range of loading conditions is formulated as a multi-objective optimization problem which is the aggregation of two objectives related to damping ratio and damping factor. By minimizing the objective function with oscillation, the characteristics between areas are contained and hence the interactions among the PSS and TCSC controller under transient conditions are modified. For evaluation of effectiveness and robustness of proposed controllers, the performance was tested on a weakly connected power system subjected to different disturbances, loading conditions and system parameter variations. The eigenvalues analysis and nonlinear simulation results demonstrate the high performance of proposed controllers which is able to provide efficient damping of low frequency oscillations.

Fuzzy Controller Design of TCSC with ANFIS to Improve the Dynamic Stability of Power System

In this paper, a new variable fuzzy control algorithm is proposed for thyristor-controlled series capacitor (TCSC) to improve power system dynamic performance. Rules of adaptive neuron fuzzy inference system (ANFIS) devise this fuzzy controller for TCSC in power system. ANFIS uses a hybrid learning algorithm to identify the membership function parameters of Sugeno-type fuzzy inference system. Consequences of this control trend are compared with PI controller and it is shown by using fuzzy controller the system has more stable power flow and less power oscillations. Simulation results signify power stability improvement of two-area power system by using fuzzy controller in TCSC than traditional PI controller.

Coordinated design of PSSs and TCSC via bacterial swarm optimization algorithm in a multimachine power system

This paper develops a novel algorithm for simultaneous coordinated designing of power system stabilizers (PSSs) and thyristor controlled series capacitor (TCSC) in a multimachine power system. The coordinated design problem of PSS and TCSC over a wide range of loading conditions is formulated as an optimization problem. The bacterial swarm optimization (BSO) algorithm is employed to search for optimal controllers parameters. By minimizing the proposed objective function, in which the speed deviations between generators are involved; stability performance of the system is improved. To compare the capability of PSS and TCSC, both are designed independently, and then in a coordinated manner. Simultaneous tuning of the bacterial swarm based coordinated controllers gives robust damping performance over wide range of operating conditions, and different disturbances in compare to optimized PSS controller based on BSO (BSOPSS) and optimized TCSC controller based on BSO (BSOTCSC). Moreover, the results are compared to the results obtained using the bacteria foraging (BF) and particle swarm optimization (PSO) to show the effectiveness of using BSO to attain a global optimal solution of the proposed coordinated design problem.

Controlling SSR of the IEEE Second Benchmark Model Using TCSC and SSSC: a Comparativestudy

This paper investigates the effect of using two types of flexible alternating current transmission system (FACTS) devices on sub-synchronous resonance (SSR) phenomenon in power system. The devises are thyristor controlled series capacitor (TCSC) and static synchronous series compensator (SSSC .)The system under study, which is the first system of the IEEE second benchmark model of SSR, is modified such that the conventional variable series capacitor is replaced by TCSC and SSSC. The effects of TCSC and SSSC controllers are studied in terms of stability and damping. The stability of the operating point of TCSC- and SSSC-compensated systems is analysed using eigenvalue analysis of the linearized model. Time domain simulations based on the nonlinear model have also been carried out. It is found that both TCSC and SSSC have increased the operating point stability regions.