Enhancement of Dynamic Performance of Transmission Line using Static Synchronous Series Compensator

Static synchronous series compensator (SSSC) belongs to the facts family. It controls the flow of power in transmission line. The SSSC is a voltage source inverter connected in series with the transmission line and injects the voltage in quadrature with line current. Demand of power is growing day after day. Installation of new transmission lines is difficult because of environmental factors. The power flow capacity of existing transmission line has to be increased which is done by using compensation devices. The main reason behind poor performance of transmission system is the power flow capacity of existing transmission line under dynamic situations subjected to disturbances. FACTS technology opens new opportunities for controlling power and increases the usable capacity. It enhances corresponding power to flow through such lines under normal and contingency conditions. Recently new advancement in FACTS technology has introduced devices for reactive power compensation.  In this paper, a case study is discussed and test system is simulated in MATLAB/Simulink under normal conditions and also under fault conditions to improve the transient stability of the system. A 132kv transmission line coming from Kohat grid station to tall grid station has been selected as a test system which is suspected to overloaded conditions due to which voltage stability could not be maintained especially during the months of June, July and August. Static synchronous series compensator (SSSC) is installed near the Kohat bus. The results of current, voltage, active power and reactive power have been analysed with and without SSSC in the test system. Results shown that the stability of power system, voltage profile and power flow capability enhances by using SSSC. Also by using SSSC the oscillations were damped very quickly as compared to the circuit without using SSSC and the stability is maintained.