Performance analysis of a hybrid DSTATCOM topology as an effective solution in distribution systems

Zig-Zag transformer is one of the best device employed for nullifying the fundamental and zero-sequence harmonic current on the customer side under balanced voltage. The customer side neutral current becomes dangerously high under polluted distribution voltage. The proposed scheme consist of a combination of Hybrid DSTATCOM topology with a Zig-Zag transformer for solving power quality issue as well as neutral current mitigation. The topology consist of an additional capacitor, which is connected in series with the parallel branch of the hybrid DSTATCOM so as to reduce the DC side capacitor voltage. The selection of the of the series capacitor is in such a way that voltage at the dc side capacitor is reduced. An enhanced PLL (EPLL) based control algorithm is used for DSTATCOM. In this scheme, active and reactive components of a particular phase current can be extracted for the generation of reference source current even under polluted utility voltage. DC link voltage is maintained to a constant value using Fuzzy logic. Fuzzy logic controller is designed so as to change the controller gain under dynamic load disturbances. The effectiveness of the new topology is confirmed using MATLAB environment. The Zig-Zag transformer performance is verified through software as well as hardware experiment.