Earticle

Flexible Alternating Current Transmission Systems (FACTS) represents a vast development in the area of power system operation and control. As we know that under heavily loaded conditions our power system is at high risks of consequent voltage instability problem. This paper gives an overview about application of series connected Flexible alternating current transmission system (FACTS) for improvement of power system performance like transfer stability, secure voltage profile and reduce the system losses etc. FACTS devices require huge capital investment. Therefore, heuristic techniques are used for optimal location and sizing of series FACTS controllers like Genetic Algorithm (GA), Particle Swarm Optimization (PSO) etc. These techniques are used to solve the optimization problem. This paper gives details of optimal placement and sizing of FACTS devices based on different evolutionary techniques which is used for minimization of transmission loss, enhancement of stability of power system. In this study one of the FACTS devices is used as a scheme for enhancement of power system stability.Proper installation of FACTS devices also results in significant reduction of transmission loss. In this review,TCSC is selected as the compensation device.

Thyristor controlled series capacitors (TCSC) damping controller is considered as a useful device to improve the stability of transmission power systems. Seeking the optimal placement of TCSC controller has become a critical issue for the power system stability. From the working point of view, the TCSC controller is used to improve the voltage magnitude, reactive power and oscillation damping of power systems. The effectiveness of the location of TCSC controller, particularly in the damping of power oscillations depends on its location and input signals in the power system during time of grid fault. In this paper, an energetic method based on controllability and observability Gramians in continuous-time is proposed to determine the optimal location of TCSC. The effectiveness of the proposed method has been verified on the 39-bus New England power system.

This paper proposes a hybrid technique for secured optimal power flow coupled with enhancing voltage stability with FACTS device installation. The hybrid approach of Improved Gravitational Search algorithm (IGSA) and Firefly algorithm (FA) performance is analyzed by optimally placing TCSC controller. The algorithm is implemented in MATLAB working platform and the power flow security and voltage stability is evaluated with IEEE 30 bus transmission systems. The optimal results generated are compared with those available in literature and the superior performance of algorithm is depicted as minimum generation cost, reduced real power losses along with sustaining voltage stability.

Protection system is used to protect components against fault as fast as possible and also to minimize the area around it from fault. Nowadays because of the existence of Distributed Generation in power system, a change is needed to be implemented for protection system at distribution network in order to ensure the electricity can be supplied to the consumer safely. With the presence of distributed generation (DG) units in distribution systems, the function of relay protection is generally going to be changed. In this paper the impact of installing Dis-tributed Generation in radial system on the directional over-current protection relay, in pres-ence of a Thyristor Controlled Series Capacitor on fault courant is investigated. The relays coordination scheme was developed through analysis for three fault location scenarios. A realistic feeder system for a case study with its scheme protection is developed in Matlab software environment.

This paper presents the application of the Modified Particle Swarm Optimization (MPSO) technique for optimal settings zones for distance relay protect 400 kV single transmission line of Eastern Algerian transmission networks at Algerian Company of Electrical and Gas (Group Sonelgaz) compensated by Thyristor Controlled Series Capacitor (TCSC) connected at midpoint for minimized active and reactive power loss. The effects of TCSC insertion on the total impedance of a protected transmission line with respect to injected variable reactance value (XTCSC) in capacitive and inductive boost mode depending of the firing angle (α) is considered. The modified setting zone protection for three zones (Z1, Z2 and Z3) is have been investigate in order to prevent circuit breaker nuisance tripping and improve the performances of distance relay protection. In this work our aim is to compare the performance of the proposed MPSO algorithm with an analytical method (AM). The findings demonstrate the outstanding performance of the proposed MPSO in terms of computation speed, rate of convergence, and feasibility. The simulation results are compared with each other, and then the more perfect algorithm is considered.

Thyristor-controlled series capacitor (TCSC) as one of the most important FACT devices can be used for various purposes such as reactive power compensation, voltage control, dynamic stability improvement and power oscillation damping in power systems. Practical aspects on sizing of TCSC elements must be considered to have the fast and reliable switching from capacitor to inductive region and vice versa which is described in this paper. The influencing factors on TCSC characteristic, the requirements of L and C, practical and exact limits of firing angle are presented by detailed analyzing and simulations. Also exact firing angle limitation and stable thyristor trigger angle are discussed for the first time.

We have proposed a new technology compensating reactance component of line and load. Because capacity of SC is static, it is not appropriate to varing reactance and causes SSR problems. TCSC is introduced for the flecxible control of reactance of SC. If SC voltage is varied when the capacitor current is constant, it can be considered that capacity of SC was varied. SO capacity of SC can be controlled by controlling the voltage of SC. Control reference voltage of SC can be obtained from the condition that sum of reactive powers in all parts is zero.

전력 시스템에서 직렬 보상기의 적용은 회로 차단기 과도 재기 전압 (Transient Recovery Voltage : TRV) 문제와 같은 다른 장치에 영향을 미친다. 본 논문에서는 TCSC (Thyristor-Controlled Series Capacitor)가 있는 경우와 없는 경우의 선로 차단기에 대한 TRV 효과를 시뮬레이션을 통해 분석하고, TCSC 설치로 인한 TRV 증가를 극복하는 효과적인 방법을 제안한다. 또한 금속 산화물 바리스터 (Metal Oxide Varistor : MOV)에 대한 제안된 보호의 영향에 대해서도 설명한다. 시뮬레이션 모델은 국내의 345 kV 송전선로를 사용하였다. 전력 시스템은 PSCAD (Power Systems Computer Aided Design) / EMTDC (Electro Magnetic Transient Direct Current)를 사용하여 모델링하였다. TRV는 송전선로 및 차단기 단자에서 단락 고장을 구현하여 분석하였고, MOV의 에너지는 보호 동작 알고리즘을 적용하여 해석하였다. 제안된 보호 방안을 적용하는 경우 TRV는 표준을 만족시키지만, 지연 시간이 증가함에 따라 MOV 에너지 용량의 증가하여야 한다. 이 결과를 적용하여 실제 전력 시스템에서 예상되는 전송 선로 고장 상태로 인한 TRV 문제를 해결할 수 있다.

The application of series compensator in a power system affects other devices such as circuit breakers transient recovery voltage (TRV) problem. In this paper, we analyze the TRV effect on a line circuit breaker in the cases with and without thyristor-controlled series capacitor (TCSC) via simulation, and suggest an effective method to overcome the increase of TRV due to the TCSC installation. It also discusses the impact of proposed protection on metal oxide varistor (MOV). A 345 kV transmission line in Korea was selected as a study case. Grid system was modelled using PSCAD (Power Systems Computer Aided Design) / EMTDC(Electro Magnetic Transient Direct Current). The TRV was analyzed by implementing a short circuit fault along the transmission line and at the breaker terminal. The proposed protection scheme, the TRV satisfies the standard. However, the MOV energy capacity increased as the delay time increased. This result can solve the TRV problem caused by the expected transmission line fault in a practical power system.

In this paper, the RCF method is applied to analyze small signal stability of power systems including thyristor controlled FACTS equipments such as TCSC. The eigenvalue sensitivity analysis algorithm in discrete systems by the RCF method are presented and applied to the power system including TCSC. The RCF analysis method enabled to precisely calculate eigenvalue sensitivity coefficients of dominant oscillation modes after periodic switching operations. These simulation results are very different from those of the conventional continuous system analysis method such as the state space equation method.

In this paper, the eigenvalue sensitivity analysis algorithm in discrete systems by the RCF method are presented and applied to the power system including TCSC. The RCF analysis method enabled to precisely calculate eigenvalue sensitivity coefficients of dominant oscillation modes after periodic switching operations. These simulation results are very different from those of the conventional continuous system analysis method such as the state space equation method

In this paper, RCF(Resistive Companion Form) analysis method which is used to analyze small signal stability problems of non-continuous systems including switching device. The RCF analysis method are applied to the power systems with the thyristor controled FACTS equipments such as TCSC. As a result of simulation, the RCF method is very powerful to calculate the oscillation modes exactly after the switching operations, and useful to analyze the small signal stability of power systems with switching devices such as FACTS equipments. As an applicable example of the RCF method in power system, the one machine infinite bus system including TCSC at generator terminal bus is investigated and the results proved that variations of oscillation modes after periodic switching operations of TCSC can be calculated exactly.

This paper presents an auxiliary TCSC controller designed for damping SSR. Damping controller for SSR is designed in frequency domain for suppressing resonance. The SSR phenomenon and the performance of damping controller simulated by using PSCAD/EMTDC. In this simulation. the power system model for SSR is IEEE benchmark Model and TCSC is simplified to controllable impedance model.

This paper presented design of an $H_{\infty}$ controller for TCSC to enhance the damping of an inter-area oscillation in KEPCO power system. TCSC location is selected by using eigne sensitivity and frequency response. Nonliner time simulation and eigenvalue analysis show that the proposed TCSC $H_{\infty}$ controller can suppress the inter-area oscillations efficiently with induced reduction model correctly.

The design of an $H{\infty}$ controller for a TCSC to enhance the damping of an inter-area oscillation in a Power system is presented. The paper describes a comprehensive and systematic way of applying the $H{\infty}$ control design algorithm in power systems. Eigen sensitivity analysis to selction a TCSC location is described. Time simulation and eigenvalue analysis show that the proposed TCSC $H{\infty}$ controller can suppress the inter-area oscillations efficiently with robustness.

TCSC is a FACTS device that can control the active power flow and current of transmission lines by adjusting line impedances. In this paper, we study the effect of TCSC on power transfer capability. A static model of TCSC is implemented in the continuation power-flow(CPF) Program and the power transfer capability is measured using the CPF. The site of TCSC is selected to increase power transfer capability by the sensitivity information provided from the CPF. The effect of TCSC with various control mode is tested in IEEE New England 30-bus system.

Thyristor-Controlled Series Compensation (TCSC) is expected to be applied in transmission systems to achieve a number of benefits. TCSC can provide such assistance for stability, as well as helping to direct flows onto desired transmission paths. This paper describess a TCSC model which can be used for typical transient and oscillatory stability studies. Also included is a discussion on relevant information to extend the modeling detail of the TCSC for use stability analysis.

TCSC can not only increase power flow but also damp low frequency oscillation by controlling firing angles of thyristors. But, a model considering voltage, current firing angles is not derived. This paper used a small signal model considirng these variables which was derived in paper [1]. TCSC model is combined with swing equation. Being related to rotor angles and firing angles of thyristors, current and synchronizing torque coefficient is reformulated. Because firing angles of thyristors can be controlled only twice within one period, swing equation is transformed to discrete time model. It is shown that low frequency oscillation can be damped by controlling firing angles in one machine infinite bus power system.

In this paper, we design a Power System Stabilizer for a Thyristor Controlled Series Capacitor(TCSC-PSS) for enhancement of power system stability. Here, PSS parameters are optimized using Genetic Algorithm(GA) in order to maintain optimal operation of TCSC. Simulation results show that the proposed control technique is superior to a conventional PSS in dynamic responses over the wide range of operating conditions and is convinced robustness and reliableness in view of structure.

KERI simulator is a analog simulator for power system at KERI power system division lab. It consist of many power system components, which are a 380V 5kVA generators, scale-downed transmission line modules, transformers, switches, PACTS(Flexible AC Transmission System) devices. As a FACTS device module, 20kVA TCSC(Thyristor Controlled Series Compensator) module was designed and implemented. In this paper, we present the design and implementation of TCSC control hardware for KERI simulator

This paper prescribe the effects of SVC & TCSC in multi-machine power system. EMTP models of two FACTS controllers are proposed to analysis the basic characteristics of SVC & TCSC and the control signal of TCR is determined by rms value which was measured in system. The oscillation model of generator is proposed to analysis the damping effect and the most effective location of TCSC in multi-machine power system is identified by the residues associated with the natural oscillation modes. The 3 generator-9 bus model system is used to demonstrate the applicability of the proposed model.