Comparison and Performance Analysis of FACTs Controller in System Stability

In large inter connected power systems, inter-area oscillations are turned to be a severe problem. Hence inter-area oscillations cause severe problems like damage to generators, reduce the power transfer capability of transmission lines, increase wear and tear on network components, increase line losses etc. This paper is to maintain the stability of system by damping inter-area oscillations. Implementation of new equipment consists of high power electronics based technologies such as FACTs and proper controller design has become an essential to provide better damping performance than Power System Stabilizer (PSS). With development of Wide Area Measurement System (WAMS), remote signals have become as feedback signals to design Wide Area Damping Controller (WADC) for FACTs devices. In this work, POD is applied to both SVC and SSSC. Simulation studies are carried out in Power System Analysis Toolbox (PSAT) environment to evaluate the effectiveness of the FACTs controller in a large area power system. Results show that extensive analysis of FACTs controller for improving stability of system.

Fault Location Method for STATCOM Connected Transmission Lines Using CCM

Determining the fault location using conventional impedance based distance relay in the presence of FACTS controllers is a challenging task in a transmission line. A new distance protection method is developed to locate the fault in a transmission line compensated with STATCOM with simple calculations. The proposed protection method considers the STATCOM injected/absorbed current to correct the fault loop apparent impedance and accordingly calculates the actual distance to the fault location. The comprehensive equations needed for apparent impedance calculation are also outlined and the performance is evaluated and tested with a typical 400 KV transmission system for different fault types and locations using MATLAB/SIMULINK software. The evaluation results indicate that the new protection method effectively estimates the exact fault location by mitigating the impact of STATCOM on distance relay performance with error less than 0.3%.

Comparison of Optimal Place and Size of TCSC and SVC for Maximum Available Transfer Capability

This paper deals with power transfer capability enhancement using two common Flexible Alternating Current Transmission Systems （FACTS） devices, Thyristor Controlled Series Capacitor （TCSC） and Static Var Compensator （SVC）. For this purpose, at first the optimal place of TCSC and SVC is investigated and the optimal size is determined. At the end, a comparison is made between the two FACTS devices. For calculating Available Transfer Capability （ATC）, Repeated Power-Flow （RPF） rule used, and the network limitations such as voltage, stability, thermal capacity, and power generation limits are taken into consideration. The proposed algorithm is run on a sample network. Results show effectiveness of TCSC in situations where the thermal limit is the dominant limitation of the network. In such situations, SVC is almost useless. It was also seen that under conditions of voltage limitations, both elements are helpful for the enhancement of ATC.

Optimal allocation of multi-type FACTS devices in power systems based on power flow entropy

Flexible AC transmission systems(FACTS)devices can effectively optimize the distribution of power flow.Power flow entropy can be applied as a measure of load distribution.In this paper,a method is proposed to optimize the distribution of power flow with the coordination of multi-type FACTS devices and establishes the corresponding mathematical models.The modified group searcher optimization(GSO)algorithm is proposed,in which the angle search is combined with chaotic search model to avoid jumping into local optimization.Compared with the different optimal allocation of multi-FACTS devices,the optimal allocation of multi-FACTS devices is achieved under the economic constraints.The locations obtained by this method can achieve the purpose of balancing power flow and enhancing the system performances.The simulations are demonstrated in an IEEE 118-bus power system with two classical types of FACTS,namely static var compensator(SVC)and thyristor controlled series Compensator(TCSC).The simulation results show that the proposed method is feasible and effective.

Press-pack IGBTs for HVDC and FACTS

The popularity of insulated gate bipolar transistors(IGBTs)for use in high-voltage direct current(HVDC)transmission and flexible AC transmission systems(FACTS)is increasing.Unfortunately,for these applications wire-bond IGBT technology has a number of shortcomings,such as insufficient current ratings for the most powerful schemes,and inability to fail to short-circuit.Press-pack IGBT technology,conversely,offers increased current ratings,and an inherent short-circuit failure mode,making it a more attractive choice for HVDC and FACTS.However,the design and manufacture of these devices requires a comprehensive understanding of the unique technical challenges,which differ markedly from those for wirebond modules or traditional pressure contact devices.Specific challenges include providing a high degree of mechanical protection for the IGBT chip against normal operating stresses.Furthermore,it is essential to achieve uniform contact pressure across each chip surface to ensure optimum performance.To achieve this,manufacturers have designed products that use rigid copper electrodes manufactured to tighter tolerances than for other pressure contact devices,such as thyristors,and products that use compliant electrodes,incorporating spring assemblies.Dynex is in the advanced stages of development of press-pack IGBT technology with demonstrated robust solutions for the technical challenges outlined in this paper.Design success has been achieved through the use of state-of-the-art simulations in conjunction with a long history of manufacturing expertise for bipolar and IGBT products.Finally,multiple press-pack IGBT variants are currently undergoing evaluation tests prior to product release.

Interactive DE for solving combined security environmental economic dispatch considering FACTS technology

This paper presents an efficient interactive differential evolution ODE） to solve the multi-objective security environmental/economic dispatch （SEED） pro- blem considering multi shunt flexible AC transmission system （FACTS） devices. Two sub problems are proposed. The first one is related to the active power planning to minimize the combined total fuel cost and emissions, while the second is a reactive power planning （RPP） using multi shunt FACTS device based static VAR compensator （SVC） installed at specified buses to make fine corrections to the voltage deviation, voltage phase profiles and reactive power violation. The migration operation inspired from biogeography-based optimization （BBO） algorithm is newly introduced in the proposed approach, thereby effectively exploring and exploiting promising regions in a space search by creating dynamically new efficient partitions. This new mechanism based migration between individuals from different subsystems makes the initial partitions to react more by changing experiences. To validate the robustness of the proposed approach, the proposed algorithm is tested on the Algerian 59-bus electrical network and on a large system, 40 generating units considering valve-point loading effect. Comparison of the results with recent global optimization methods show the superiority of the proposed IDE approach and confirm its potential for solving practical optimal power flow in terms of solution quality and convergence characteristics.

Optimal Coordinated Operation of Distributed Static Series Compensators for Wide-area Network Congestion Relief

Relieving network congestions is a critical goal for the safe and flexible operation of modern power systems, especially in the presence of intermittent renewables or distributed generation. This paper deals with the real-time coordinated operation of distributed static series compensators(DSSCs) to remove network congestions by suitable modifications of the branch reactance. Several objective functions are considered and discussed to minimize the number of the devices involved in the control actions, the total losses or the total reactive power exchanged, leading to a non-convex mixed-integer non-linear programming problem. Then, a heuristic methodology combining the solution of a regular NLP with k-means clustering algorithm is proposed to get rid of the binary variables, in an attempt to reduce the computational cost. The proposed coordinated operation strategy of the DSSCs is tested on several benchmark systems, providing feasible and sufficiently optimal solutions in a reasonable time frame for practical systems.