MPC Based TLSC-DSTATCOM with VIKOR Approach to Reduce Switching Frequency and Capacitor Voltage Balancing

In this paper, a three-leg split capacitor distribution static compensator (TLSC-DSTATCOM) with chopper circuit is used to mitigate current related power quality issues in the distribution system. In conventional TLSC-DSTATCOM, the split capacitor voltages are unbalanced and switching frequency is high under DC load conditions, which leads to increases in source current THD and switching losses. In order to balance the split capacitor voltages during DC load conditions, a TLSC-DSTATCOM with chopper circuit is used in the proposed method. TLSC-DSTATCOM is controlled using model predictive control (MPC) to increase the steady state response, and control of the chopper circuit is based on the predicted dc link voltage from the optimal switching state and the reference dc link voltage. High switching frequency is a limitation of MPC, considering switching frequency as a cost function with a weighting factor to minimizing switching frequency of voltage source inverter (VSI). When considering two or more cost functions in MPC, it will be difficult to select optimal weighting factors for the intended output. To minimize the complexity of the weighting factor tuning, VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) technique is used in TLSC-DSTATCOM. The proposed method is validated using simulation and experimental tests.