MANAGING REACTIVE POWER USING CASCADED MULTILEVEL D-STSTCOM IN SUB-TRANSMISSION/11KV DISTRIBUTION SYSTEM

Abstract

This thesis investigates the problems associated with 11kV distribution system in terms of delivery of clean power and their solutions, in particular the reactive power compensation. The abnormalities in the distribution system has been modelled and analysed. Any deviation from the ideal condition has been computed in the time domain at every instant. The deviation so computed has been compensated by use of the D-STATCOM in the real time. A detailed model of 3-phase bridge D-STATCOM for line voltage upto 11kV has been developed using cascaded multilevel voltage source converter structure (VSCs). A same phase multilevel PWM control has been developed for the multilevel inverter for the medium voltage distribution system. The scheme has been replaced for the control of the D-STATCOM so that it maintains the reactive power and THD under control by keeping all the voltage and current waveforms as per their standard sinusoidal forms. The proposed system has been presented with the mathematical equations and block diagrams for detailed illustrations of the control loops. A SIMULINK model using MATLAB/SIMULINK platform has been used to present the proposed system. Simulation result for different operating condition has been obtained and analysed for viewing the merit of the proposed control technique. The obtained results corroborate the effectiveness of control scheme.