ABSTRACT

 Flexible AC Transmission System (FACTS) devices such as Static Var Compensator (SVC) and Static Synchronous Compensator (STATCOM) when placed at the midpoint of a long transmission line play an important role in controlling the reactive power flow into the power network. This Thesis explores the effect of STATCOM and SVC on voltage stability. The Nigerian 24-bus system has been used to demonstrate the ability of STATCOM and SVC in improving the voltage stability of a power system network. The structure of STATCOM and SVC are explained and their impact on midpoint voltage regulation. Furthermore, the performance of the STATCOM is compared with that of conventional static var compensator (SVC). Newton Raphson load flow analysis was carried out on the Nigerian 24-bus 330KV network using Neplan Engineering software. It was discovered that STATCOM provided a high reactive power support than SVC and also improved the static voltage of the buses to which it was connected to, as well as other buses that were not directly connected to the STATCOM. Although SVC improved the voltages of the buses to which it was connected to as well as other buses not directly connected to it, STATCOM displayed a greater improvement of the bus voltages to which it was connected to, with STATCOM offering the highest voltage improvement of 1.0388pu while SVC offered an improvement of 1.0282pu. The real and reactive power losses in the system network were reduced when STATCOM and SVC were inserted into the network, however the real and reactive power losses were lower when STATCOM was inserted than when SVC was inserted with STATCOM having a reactive power loss of 467.2285MVar giving a total reduction of 32.01% in the reactive power loss of the network while SVC had a total reactive power loss of 481.4609MVar giving a total reduction of 29.94% in the reactive power loss in the network. Similarly, STATCOM had an active power loss of 53.8229MW giving a total reduction of 17.96% in the active power loss of the network while SVC had an active power loss of 54.2594MW giving a total reduction of 17.30% in the active power loss of the network.