Investigations on stability improvement by implementing SSSC optimally with X/R ratio

Abstract

Series compensation is widely used to enhance the transmittable power through an existing transmission line. This is achieved by controlling series reactance of the transmission line by injecting a voltage in series with transmission line and is perpendicular to the line current. However, X/R ratio of the transmission line gets deteriorated with series compensation. X/R ratio plays an important role in maintaining stability and damping oscillation in power system. In the proposed scheme, X/R ratio of the line has been included as one of the constraints along with midpoint voltage and power balance equation, with the objective of minimizing power system losses while enhancing the power. It is found that by maintaining X/R ratio of the transmission line same as the original designed value, stability of the system can be improved while making an attempt to enhance the transmittable power capacity. Steady state and transient stability, voltage stability and damping oscillations are analyzed with proposed optimal control of statis synchronous series compensator (SSSC), and results are produced. Validation of proposed optimal control of SSSC is done by using MATLAB platform for enhancing transmittable power of a 400 kV, 400 km transmission line and results are presented here. The paper investigates the effectiveness of the proposed optimization technique on improvement of power system stability and oscillations damping as well.