This paper deals with the design and implementation of

a multilevel voltage source converter based static synchronous

compensator (STATCOM) employing an effective modulation

control technique simulated in a MATLAB Simulink

environment. The main objective of this paper is to maintain the

voltage stability by compensating the reactive power in the power

system. Hence, a new efficient control strategy is proposed, in

order to reduce the voltage fluctuations like sag and swell

conditions and also to isolate current and voltage harmonics in

the transmission system. The multilevel STATCOM which can be

used at the point of common coupling (PC C), for improving

power quality is modelled and simulated using proposed control

strategy and the performance is compared by applying it to an

llOkv line with and without STATCOM. Relative Harmonic

analysis is also discussed in this paper based on the total

harmonic distortion (THD) calculations.