Thyristor Controlled Series Compensator Research Articles

Improved Power System Stability Using Backtracking Search Algorithm for Coordination Design of PSS and TCSC Damping Controller

Power system oscillation is a serious threat to the stability of multimachine power systems. The coordinated control of power system stabilizers (PSS) and thyristor-controlled series compensation (TCSC) damping controllers is a commonly used technique to provide the required damping over different modes of growing oscillations. However, their coordinated design is a complex multimodal optimization problem that is very hard to solve using traditional tuning techniques. In addition, several limitations of traditionally used techniques prevent the optimum design of coordinated controllers. In this paper, an alternate technique for robust damping over oscillation is presented using backtracking search algorithm (BSA). A 5-area 16-machine benchmark power system is considered to evaluate the design efficiency. The complete design process is conducted in a linear time-invariant (LTI) model of a power system. It includes the design formulation into a multi-objective function from the system eigenvalues. Later on, nonlinear time-domain simulations are used to compare the damping performances for different local and inter-area modes of power system oscillations. The performance of the BSA technique is compared against that of the popular particle swarm optimization (PSO) for coordinated design efficiency. Damping performances using different design techniques are compared in term of settling time and overshoot of oscillations. The results obtained verify that the BSA-based design improves the system stability significantly. The stability of the multimachine power system is improved by up to 74.47% and 79.93% for an inter-area mode and a local mode of oscillation, respectively. Thus, the proposed technique for coordinated design has great potential to improve power system stability and to maintain its secure operation.

Impact of TCSC Installation on ATC in a System Incorporating Wind and Hydro Generations

This paper examines the impact of installing Thyristor Controlled Series Compensator (TCSC) on Available Transfer Capability (ATC) in a system with wind and hydro generations. Wind resource is modelled as an active power generation, wind power being decided by average wind velocity values over 24 hour duration. Hydro power output is represented as a polynomial in two variables, water discharge and volume of water in the reservoir. The variation in ATC is first observed with varying wind and hydro generations over 24hours and then a steady state model for TCSC is used to bring out its effect on ATC. The ATC values with TCSC are obtained by varying the location of the device through different lines. The site which gives the maximum values for ATC is chosen as the optimal placement of TCSC. Modified IEEE 24 bus reliability test system (RTS) is used for the study.

Comparison of BBO, WIPSO & PSO Techniques for the Optimal Placement of FACTS Devices to Enhance System Security

Nowadays power systems are heavily loaded and are being operated in ways not originally envisioned. Flexible AC Transmission System (FACTS) devices play a vital role in improving the static as well as dynamic performance of the power systems. FACTS devices are based on solid-state control and so the control actions at far higher speed is possible. However the location and rating of the FACTS devices play a major role in deciding the extent to which the objective of improving the system performance is achieved in a cost effective manner. In this work an objective function comprising of cost, line loadings and load voltage deviations is proposed to tap maximum benefits out of their installation and the weights assigned to them decide their relative importance. FACTS devices such as Thyristor Controlled Series Compensator (TCSC) and Static VAR Compensator (SVC) are considered. The optimization is carried out considering four parameters namely the number of FACTS device, location, type and rating of the device. In this work three cases (only TCSC, only SVC, TCSC & SVC) are considered forthe optimal placement of the devices, using PSO, WIPSO and BBO techniques.

Optimal Placement of FACTS Devices to Improve Power Flow Using Bees Algorithm

Flexible AC Transmission System (FACTS) device has gained popularity recently as an essential device in power systems. The introduction of FACTS technology in power systems has seen increased flexibility and control of power flow along the transmission lines. This paper focuses on three FACTS devices namely Static VAR Compensator (SVC), Thyristor Controlled Series Capacitor (TCSC) and Unified Power Flow Controller (UPFC). The devices will be optimally placed to simultaneously minimize system real power loss and maximize the inter-tie flow using Bee Algorithm (BA). BA is a simple and efficient heuristic search method based on the foraging behavior of honey bees searching for the best food source in a recently proposed multi objective optimization algorithm. The performance of presented BA algorithm is tested and verified on the IEEE 30-bus power systems. A Genetic Algorithm (GA) configured for the same purpose is used for evaluation. Results show the difference of performance of the devices used in this situation. The results achieved in this work illustrated that BA can successfully be used to solve the nonlinear problems related to power system optimization. Keywords— Bee algorithm, Static VAR compensator, Thyristor Controlled series compensator,

Optimal Placement of Thyristor Controlled Series Compensator (TCSC) on Nigerian 330kV Transmission Grid to Minimize Real Power Losses

Optimal Placement of Thyristor Controlled Series Compensator (TCSC) on Nigerian 330kV Transmission Grid to Minimize Real Power Losses

Oppositional biogeography-based optimisation applied to SMES and TCSC-based load frequency control with generation rate constraints and time delay

This article introduces biogeography-based optimisation (BBO) and oppositional BBO for solving load frequency control (LFC) in power system. Two widely employed test systems, viz. two-area multi-unit thermal-thermal and three-area thermal power plant, are considered for analysis. To make the study realistic, inherent power system nonlinearities like time delay, generation rate constraint and reheater are included. 2nd order Pade approximation is used to find linear model of time delay. To provide additional damping to frequency and tie-line power oscillations caused by sudden load perturbation, optimal thyristor controlled series compensator (TCSC) and superconducting magnetic energy storage (SMES) are design in coordination to LFC for the concerned power systems. An extensive comparative analysis is performed to established superiority of proposed method over other recently published algorithms. Simulation results show that coordinated LFC-TCSC-SMES controller yields greater dynamic performance compared to other. Finally, sensitivity analysis is performed to demonstrate the robustness of the proposed controller.

Oppositional biogeography-based optimisation applied to SMES and TCSC-based load frequency control with generation rate constraints and time delay

This article introduces biogeography-based optimisation (BBO) and oppositional BBO for solving load frequency control (LFC) in power system. Two widely employed test systems, viz. two-area multi-unit thermal-thermal and three-area thermal power plant, are considered for analysis. To make the study realistic, inherent power system nonlinearities like time delay, generation rate constraint and reheater are included. 2nd order Pade approximation is used to find linear model of time delay. To provide additional damping to frequency and tie-line power oscillations caused by sudden load perturbation, optimal thyristor controlled series compensator (TCSC) and superconducting magnetic energy storage (SMES) are design in coordination to LFC for the concerned power systems. An extensive comparative analysis is performed to established superiority of proposed method over other recently published algorithms. Simulation results show that coordinated LFC-TCSC-SMES controller yields greater dynamic performance compared to other. Finally, sensitivity analysis is performed to demonstrate the robustness of the proposed controller.

Optimal Placement of Thyristor Controlled Series Compensators for Sensitive Nodes in Transmission System Using Voltage Power Sensitivity Index

Optimal Placement of Thyristor Controlled Series Compensators for Sensitive Nodes in Transmission System Using Voltage Power Sensitivity Index

Coordination Tuning PID-PSS and TCSC Based Model of Single Machine Infinite-Bus Using Combination Bacteria Foraging-Particle Swam Optimization Method

The power system requires optimal tuning of automatic voltage regulator (AVR) controller and power system stabilizer (PSS) parameters to get a satisfactory operation. With the increase of transmission line loading over long distances, the use of PSS in some cases may not provide sufficient damping. Application method to get the optimal parameter tuning individual controller causes the AVR to improve voltage regulation and PSS to increase the damping of the system. Simultaneous tuning of AVR, PSS and flexible ac transmission systems (FACTS) damping controller is needed to guarantee a kind closed loop system outcome and to obtain a better voltage regulation and oscillation damping in the system. This paper presents coordination tuning power system stabilizer and a thyristor controlled series compensator (TCSC) using evolutionary computation. The problem of obtaining the optimal controller parameters was formulated as an optimization problem and bacteria foraging-particle swarm optimization with time varying acceleration-differential evolution algorithm applied to solve the optimization problem. The parameters such as proportional gain, integral factor, differential coefficient were selected and optimized by bacteria foraging-particle swarm optimization with time varying acceleration-differential evolution algorithm (BFOPSOTVACDE). The suggested methods applied to tuning PSS and TCSC are compared to another method, as shown in the result. Performance index of systems obtained using suggested method was 0.9053.

Design and analysis of tilt integral derivative controller with filter for load frequency control of multi-area interconnected power systems

In this paper, a novel Tilt Integral Derivative controller with Filter (TIDF) is proposed for Load Frequency Control (LFC) of multi-area power systems. Initially, a two-area power system is considered and the parameters of the TIDF controller are optimized using Differential Evolution (DE) algorithm employing an Integral of Time multiplied Absolute Error (ITAE) criterion. The superiority of the proposed approach is demonstrated by comparing the results with some recently published heuristic approaches such as Firefly Algorithm (FA), Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) optimized PID controllers for the same interconnected power system. Investigations reveal that proposed TIDF controllers provide better dynamic response compared to PID controller in terms of minimum undershoots and settling times of frequency as well as tie-line power deviations following a disturbance. The proposed approach is also extended to two widely used three area test systems considering nonlinearities such as Generation Rate Constraint (GRC) and Governor Dead Band (GDB). To improve the performance of the system, a Thyristor Controlled Series Compensator (TCSC) is also considered and the performance of TIDF controller in presence of TCSC is investigated. It is observed that system performance improves with the inclusion of TCSC. Finally, sensitivity analysis is carried out to test the robustness of the proposed controller by varying the system parameters, operating condition and load pattern. It is observed that the proposed controllers are robust and perform satisfactorily with variations in operating condition, system parameters and load pattern.

Coordinated design of PSS and TCSC to mitigate interarea oscillations

Abstract Thyristor controlled series compensator (TCSC) as a promising series flexible AC transmission system (FACTS) device is generally used for controlling the real power flow in transmission lines. It can increase the system stability as the complementary functionality by minimizing the power oscillations. The effectiveness of TCSC in its primary and supplementary applications depends on the selection of its optimal location and defining a proper input signal. In this paper, a new method based on the active power sensitivity approach is applied to find the optimal location of TCSC. In addition, Hankel singular values (HSVs) and right half plane-zeros (RHP-zeros) analyses have been proposed to find the most appropriate stabilizing input signal for the supplementary functionality of TCSC to damp out the interarea modes of oscillation. Finally, the optimal design of power oscillation damper (POD) and simultaneous coordinated design of power system stabilizer (PSS) and POD are implemented separately in a large-scale power system. The tuning problem of POD-TCSC parameters as well as the coordinated POD-TCSC & PSS are converted to a multi-objective optimization problem and solved using particle swarm optimization (PSO) algorithm. The performance of the proposed method has been validated through eigenvalue analysis and nonlinear time domain simulation in a 16-machine 68-bus test system. The simulation results show a satisfactory robust performance with an excellent capability in damping of local and interarea power oscillations.

Optimal placement of TCSC using controllability Gramian to damp power system oscillations

Summary The increase of the scale and complexity of interconnected power systems leads to power system oscillations. Therefore, the electric network needs to be improved to be more stable. One type of flexible AC transmission system devices, namely, the thyristor-controlled series compensator (TCSC), can be placed in the transmission line to increase stability margins and dampen power oscillations by means of adjusting the impedance of the compensated line. The efficiency and robustness of TCSC controller depend on its optimal location in network. Hence, finding the optimal placement for TCSC has become a key issue. In this paper, a novel method based on a two-step approach is proposed to find the optimal location for TCSC. First, the energetic approach based on the combination of the controllability Gramian with the balanced realization reduction technique is applied to search feasible locations, and then the transient stability analysis is performed to compare and determine the optimal location through various test cases. The effectiveness of the proposed method has been demonstrated on the IEEE 39-bus England network. Copyright © 2015 John Wiley & Sons, Ltd.

Pattern Recognition Application of Support Vector Machine for Fault Classification of Thyristor Controlled Series Compensated Transmission Lines

Application of series compensation in extra high voltage (EHV) transmission line makes the protection job difficult for engineers, due to alteration in system parameters and measurements. The problem amplifies with inclusion of electronically controlled compensation like thyristor controlled series compensation (TCSC) as it produce harmonics and rapid change in system parameters during fault associated with TCSC control. This paper presents a pattern recognition based fault type identification approach with support vector machine. The scheme uses only half cycle post fault data of three phase currents to accomplish the task. The change in current signal features during fault has been considered as discriminatory measure. The developed scheme in this paper is tested over a large set of fault data with variation in system and fault parameters. These fault cases have been generated with PSCAD/EMTDC on a 400 kV, 300 km transmission line model. The developed algorithm has proved better for implementation on TCSC compensated line with its improved accuracy and speed.

Optimal Location of Thyristor-Controlled Series Compensation and Static VAR Compensator to Enhance Steady-state Performance of Power System with Wind Penetration

Wind generation connection to power system affects steady-state and transient stability. Furthermore, this effect increases with the increase of wind penetration in generation capacity. In this article, optimal location of flexible AC transmission system devices is carried out to solve the steady-state problems of wind penetration using a genetic algorithm. Case study is carried out on modified IEEE 39-bus system with wind penetration increases by 50%; the system suffers from outage of one generator with load decrease in one of system buses by 15%. The system suffers from minimum voltage reduction, total loss increase, and violation of power and power angle limits. Series and shunt flexible AC transmission system devices are used in this article. Results showed that series flexible AC transmission system devices in certain range are able to solve these problems associated with wind penetration in power systems with acceptable cost saving.

Lead Lag Controller of TCSC Optimized by Bees Algorithm for Damping Low Frequency Oscillation Enhancement in SMIB

Power system is often vulnerable to low frequency electromechanical oscillations due to the interconnected configuration. A common lead-lag controller is used for one of the FACTS devices known as Thyristor Controlled Series Compensator (TCSC) as supplementary controller for damping purpose in order to improve transient stability and power oscillation damping of the system. As Bees Algorithm (BA) optimized the parameters of the TCSC lead-lag controller, thus its named is TCSC-BALL. In this study, the optimization problem is formulated as a constrained optimization with the main objective is to move the system eigenvalues to the left as far as possible in order to improve the system stability. Then, the system is simulated in MATLAB by using The Phillips-Heffron model for single machine infinite bus (SMIB) with responses of increases in mechanical power at t=1 second. The performance is observed in terms of electromechanical eigenvalues position on s-plane and damping responses of low-frequency oscillations where the system implemented with the TCSC-BALL controller given better results as compared to the system without and with the inclusion of conventional Power System Stabilizer (CPSS).

Comparison of SVC and TCSC Installation in Transmission Line with Loss Minimization and Cost of Installation via Particle Swarm Optimization

The paper presents a comparison of performance Static Var Compensator (SVC) and Thyristor Controlled Series Compensator (TCSC) with objective function to minimize the transmission loss, improve the voltage and monitoring the cost of installation. Simulation performed on standard IEEE 30-Bus RTS and indicated that EPSO a feasible to achieve the objective function.

FACTS Devices Cost Recovery During Congestion Management in Deregulated Electricity Markets

In future electricity markets, flexible alternating current transmission system (FACTS) devices will play key role for providing ancillary services. Since huge cost is involved for the FACTS devices placement in the power system, the cost invested has to be recovered in their life time for the replacement of these devices. The FACTS devices in future electricity markets can act as an ancillary services provider and have to be remunerated. The main contributions of the paper are: (1) investment recovery of FACTS devices during congestion management such as static VAR compensator and unified power flow controller along with thyristor controlled series compensator using non-linear bid curves, (2) the impact of ZIP load model on the FACTS cost recovery of the devices, (3) the comparison of results obtained without ZIP load model for both pool and hybrid market model, (4) secure bilateral transactions incorporation in hybrid market model. An optimal power flow based approach has been developed for maximizing social welfare including FACTS devices cost. The optimal placement of the FACTS devices have been obtained based on maximum social welfare. The results have been obtained for both pool and hybrid electricity market for IEEE 24-bus RTS.

Challenges in Model Predictive Control Application for Transient Stability Improvement Using TCSC

Performance of a system is always dominated by constraints rather than dynamics. Conventional controllers determine off-line, a feedback policy that provides optimal control action based on minimization of one or more cost functions with or without constraints using linear or nonlinear model of the system. Increased system complexity and demanding performance requirements have rendered classical control laws inadequate in spite of their simplicity as in case of PID loop or robustness in case of H2 or H∞ control designs. The only generic control that can meet these challenges is Model Predictive Control (MPC). The most challenging MPC application would be maintaining stability after large disturbances in highly nonlinear, complex and hybrid system such as power system. The practical difficulties are due to large system having strong interactions in various parameters with hard constraints. The paper discusses various issues in tuning and maintaining constraints on states and control variables for a Single Machine Infinite Bus (SMIB) system using Thyristor Controlled Series Compensator (TCSC) as a controller.

Backstepping silding-mode control of nonlinear TCSC System based on adaptive observer

This paper proposes new approaches for nonlinear thyristor controlled series compensator (TCSC) controller design. The uncertain parameter and external disturbances are considered for practical implementation in power systems. The control law and the adaptive law are designed separately, which can avoid the oscillation of states caused by the coupling between parameter estimator and system states. The adaptive laws of uncertain parameters are estimated by using adaptive observer. The designed adaptive law can ensure that estimation error converge to zero in finite time. Furthermore, the backstepping control and sliding-mode control method is adopted to derive the control law recursively. By using the proposed method, all the state variables in the TCSC system will theoretically attain stability and eventually converge to desired values. Compared with other algorithms, the oscillation amplitudes of transient responses are reduced by nearly half, and the time of reaching steady state is shortened by at least 12%. The results indicate better performance of the proposed controller in both the transient and steady states.

English

The increase in power demand has forced the power system to operate closer to its stability limit. Voltage instability and line overloading have become challenging problems due to the strengthening of power system by various means. The nature of voltage stability can be analysed by the production, transmission and consumption of reactive power. One of the major causes of voltage instability is the reactive power unbalancing which occurs in stressed condition of power system. Flexible AC transmission system (FACTS) devices play an important role in improving the performance of a power system, but these devices are very costly and hence need to be placed optimally in power system. FACTS device like static var compensator (SVC) and thyristor controlled series compensator (TCSC) can be employed to reduce the flows in heavily loaded lines, resulting in a low system loss and improved stability of network. In this paper, a method based on line stability index, real power performance index and reduction of total system VAR power losses has been proposed to decide the optimal location of TCSC. Now a day, Voltage Stability has become a major concern in power systems planning and operation. This problem has become very complex due to the continuous growing on system interconnections and demand for electricity and also due to economical and environmental constraints to properly expand the system. This has increased the importance of implementing suitable and efficient techniques for improving voltage stability of stressed power system. FACTS are one aspect of the power electronics revolution that is taking place in all areas of electric energy.