Enhancement of power transmission capability of East - West interconnector using controlled series compensation

Abstract

Series inductive reactance of a given transmission line is a significant governing factor for the power transmission capability of that line and as the length of line increases beyond a certain range, this reactance may impose considerable limitations on the amount power that can be transferred without violating the prudent operational constraints. Transfer beyond that level can make the system significantly stressed and may even drive into the region of instability. In many practical cases this transfer limit has been observed to be noticeably lower than the thermal capability of conductors physically used to construct the line and hence creates a scope for finding ways to exploit this otherwise unused capacity. In the cases, where the transmission lines in discussion are interconnections among utilities, urge for maximum capacity utilization is much stronger due the constraints related to additional line construction. This dissertation deals with enhancement of power transmission capability of interconnections using series capacitive compensation. In most of the real world cases, tielines among utilities are medium to long high voltage lines, which are usually more susceptible to the power, transfer limitations imposed by series inductive reactance. Introducing series capacitive compensation provides with a negative reactance, resulting in a reduced net transfer reactance between two ends of a transmission line and hence the electrical length of the line becomes shorter to facilitate loading towards thermal limit. The Two-Area system and an approximate model of the Western Grid of Bangladesh Power System network have been used as case study; both old and new East West Interconnection has been considered. Controlled series compensation has been applied through Thyristor Controlled Series Capacitor. Improvement of steady state, dynamic and transient performance by applying series compensation has been presented based on the results obtain by standard static and dynamic analyses, i.e., Load Flow, Continuation Power Flow, Modal Analysis and Transient Analysis. Comparison of loading margins, corresponding to Saddle-Node and Hopf Bifurcation of the system, with and without compensation has been performed to reveal the effect of Series compensation' on transmission capability. Financial feasibility of series compensation project for these interconnections has been performed in a simplified manner arid findings are presented in the thesis.