Congestion Management in Deregulated Power System using Facts Controller

Congestion in the transmission lines is one of the technical problems that appear particularly in the deregulated environment. There are two types of congestion management methodologies to relieve it. One is non-cost free methods and another is cost-free methods, among them later method relieves the congestion technically whereas the former is related with the economics. In this paper congestion is relieved using cost free methods. Using FACTS devices, congestion can be reduced without disturbing the economic matters. STATCOM and UPFC are two mainly emerging FACTS devices and they are used in this paper to reduce the congestion. Above method is tested on 5-bus system and it can be extended to any practical system. FACTS devices can be an alternative to reduce the flows in heavily loaded lines, resulting in an increased power capability, low system loss, improved stability of the network, by controlling the power flows in the network. Modeling, simulation and analysis of 5 bus system in MATLAB environment is proposed in this paper. Comparison with and without FACTS devices is done to control the power flow and obtain the power system steady state operation. The same system is again analyzed under dynamic conditions and the performance of these devices is observed. Keywords— FACTS, Congestion, UPFC , STATCOM, Power FlowDynamic analysis ,Steady state Analysis INTRODUCTION Growth in load demand and the push to change the generation sources to smaller plant utilizing renewable energy sources along with uncertainty of transaction is likely to strain existing power system. This will lead to transmission system functioning closer to their operating limits and caused increased congestion .Therefore ensuring the transmission system is flexible enough to meet new and less predictable power supply and demand condition in competitive electricity market will be a real challenge. In India the power sector was mainly under the government ownership (>95% distribution and ~98% generation) under various states and centaral government utilities, till 1991. The remarkable growth of physical infrastructure was facilitated by four main policies: 1) centralized supply and grid expansion 2) large support from government budgets, 3) development of sector based on indigenous resources. In mid 1990’s Orissa began a process of fundamental restructuring and deregulation of the state power sector. Thereby effective means for congestion management has become an increasingly important issue, especially for deregulated system. New enabling technologies that can maintain the stability and reliability of power system while handling large volume of transmission are able to provide solution .One example of such technology is the Flexible AC Transmission Sysytem .The ability of FACTS controller to support and control power flows in system networks is well known [1-3]. And it is anticipated that the application of FACTS controller will grow in future power system .The UPFC and STATCOM are the example of second and third generation type of FACTS controller, based on power electronics switches. UPFC has the advantage of controlling both active and reactive power flow simultaneously over STATCOM. The first aspect is the flexible power system operation according to the power flow control capability of FACTS devices. The other aspect is the improvement of transient and steady-state stability of power systems. FACTS devices are the right equipment to meet these challenges [7]. The first aspect is the flexible power system operation according to the power flow control capability of FACTS devices. The other aspect is the improvement of transient and steady-state stability of power systems. FACTS devices are the right equipment to meet these challenges [7]. International Journal of Engineering Research and General Science Volume 2, Issue 6, October-November, 2014 ISSN 2091-2730 654 www.ijergs.org I. FLEXIBLE AC TRANSMISSION SYSTEM Flexible AC Transmission System (Facts) is a new integrated concept based on power electronic switching converters and dynamic controllers to enhance the system utilization and power transfer capacity as well as the stability, security, reliability and power quality of AC system interconnections. II. UPFC STRUCTURE, OPERATION AND CONTROL Two main blocks of UPFC are Shunt inverter and series inverter. Fig 1: Block diagram of UPFC