International Journal of Computer Applications (0975 – 8887) Volume 72– No.11, May 2013 16 Voltage Profile Analysis during Fault with STATCOM Amit Debnath Deptt. Of Electrical Engineering Tripura University (A Central University) India Champa Nandi Assistant Professor Deptt. Of Electrical Engineering Tripura University, India ABSTRACT This paper deals with comparative study of voltage and angle stability analysis with and without STATCOM. This paper makes the assumption that under voltage is caused by a Single phase to ground fault. Single phase to ground fault is applied in IEEE 57 bus system for analysis the effected voltage dip area in IEEE 57 bus system. The effect of fault on voltage profile and angle of IEEE 57 bus system has been analyzed with and without STATCOM. The studies are performed based on MATLAB software package tool box. General Terms STATCOM FACTS Controller Algorithm, Fault Algorithm, FACTS, MATLAB software package tool box. Keywords Power flow, STATCOM, FACTS Controller, Single line to ground fault, under voltage 1. INTRODUCTION Power flow is very important tool for the analysis power systems and it is used in operational and planning [2]. They are necessary for economic scheduling and exchange of power between utilities. In this analysis, iterative techniques are used due to there no known analytical method to solve the problem. This resulted nonlinear set of equations or called power flow equations are generated. The principal information of power flow analysis is to find the unspecified bus voltage angles and magnitudes, active and reactive powers, [6] as well as line loadings and their associated real and reactive losses for certain generation and load conditions. Recent attention on the providing & demanding of power to the entire load while maintaining the voltage magnitude at an acceptable range is one of the major system constraints in transmission and distribution of power system. Power Generation and Transmission is a complex process, requiring the working of many components of the power system in tandem to maximize the output. One of the main components to form a major part is the reactive power in the system. It is required to maintain the voltage to deliver the active power through the lines. Loads like motor loads and other loads require reactive power for their operation. To improve the performance of ac power systems, we need to manage this reactive power in an efficient way and this is known as reactive power compensation. There are two aspects to the problem of reactive power compensation: load compensation and voltage support. Load compensation consists of improvement in power factor, balancing of real power drawn from the supply, better voltage regulation, etc. of large fluctuating loads. Voltage support consists of reduction of voltage fluctuation at a given terminal of the transmission line. Two types of compensation can be used series and shunt compensation. These modify parameters of the system to give enhanced VAR compensation. The VAR compensators like the STATCOM have been developed. The development and use of STATCOM FACTS controllers for power transmission systems has led to the application of these controllers to improve the stability of power networks [3] [4]. Many studies have been carried out and reported in the 1iterature on the use of these controllers in a variety of voltage stability applications, proposing diverse control schemes and location techniques for enhancing voltage oscillation control [5].These quite satisfactorily do the job of absorbing or generating reactive power with a faster time response and come under Flexible AC Transmission Systems (FACTS). This allows an increase in transfer of apparent power through a transmission line, and much better stability by the adjustment of parameters that govern the power system i.e. current, voltage, phase angle, frequency and impedance. In a transmission line three phase fault occur in order of frequency of occurrence. The path of fault current may have either zero impedance, which is called a bolted short circuit, or nonzero impedance. When this types of three phase faults occurs the magnitude of bus voltage cannot exist the suitable range, either voltage drops or high. To prevent this effect, STATCOM FACTS controller is the best solution for maintain bus voltage magnitude in a suitable range [9]. 2. STATCOM OVERVIEW A static synchronous compensator (STATCOM), also known as a "static synchronous condenser" ("STATCON"), is a regulating device used on alternating current electricity transmission networks [7]. STATCOM is a self commutated switching power converter supplied from an appropriate electric energy source and operated to produce a set of adjustable multiphase voltage, which may be coupled to an AC power system for the purpose of exchanging independently controllable real and reactive power. The controlled reactive compensation in electric power system is usually achieved with the variant STATCOM configurations. The STATCOM has been defined with following three operating structural components. First component is Static: based on solid state switching devices with no rotating components; second component is Synchronous: analogous