SERIES CAPACITORS COMBINED WITH STATIC VAR COMPENSATORS FOR ENHANCEMENT OF STEADY-STATE VOLTAGE STABILITIES

Abstract

The world has evolved very rapidly for the past few years. Huge developments have taken place in many countries. In order to support these progressive developments, a huge amount of energy is needed, in terms of electricity. Thus, the power system now-a-days, becomes more and more complicated and large, just to ensure enough energy for all activities. Due to this complexity, the power engineers would face problems like power system stability and power quality, among others. The demand of the electrical energy is ever increasing and it is desired to use the existing transmission network to its thermal stability limits. The transmission capacity can be increased by using certain compensation devices. Both series capacitor and static VAR compensators can contribute to power systems voltage stabilities. Combining these two methods is the subject of this thesis. Effect of the presence of series capacitor on static VAR compensator controller parameters and ratings required to stabilize load voltages at certain values are highlighted. The interrelation between series compensation and the SVC controller gains and droop slopes and the SVC rating are found. For any large power system represented by its equivalent two nodes system, the power/voltage nose curves are found and their influences on the maximum power/critical voltage are studied. This is the main aim of the thesis, effects of series capacitor alone forms the first part of this thesis, static VAR compensator (SVC) effects alone is given in another study. The influence of the series capacitor on compensator gains, reference voltage values and ratings are given in detail. The studied system represents any large system seen from the load node under consideration. Static VAR compensator rating and controller references and gains are found in order to stabilize load voltage at certain specified values. Interrelation between these two means parameters are highlighted.