Power quality evaluation of photovoltaic grid interfaced cascaded H-bridge nine-level multilevel inverter systems using D-STATCOM and UPQC

The enhancement in Power Quality (PQ) becomes essential to increase the overall performance of equipment in utility-grid tied systems. To enhance PQ, this paper enumerates operational impact of Distribution Static Compensator (D-STATCOM) and Unified Power Quality Conditioner (UPQC) into a cascaded H-bridge Nine-Level Multi-Level Inverter (NL:MLI). The effectiveness of proposed topology is evaluated at a constant 200 V DC voltage and two SPV arrays of 100 kW each. A PQ comparative analysis is presented under faulted conditions at linear load. In order that the proposed system operates effectively under changing environment conditions, the implementation of a competent control techniques is dominant. Consequently, the control approach for D-STATCOM and UPQC compensates reactive power requirement of load and utility-grid. Total Harmonic Distortion (THD) and DC offset current are estimated, with distortion-less current-voltage waveforms obtained at coupling points. THD levels are validated in agreement with IEEE-519 standard. Indeed, the effectiveness of UPQC is demonstrated by feeding excess power through SPV arrays into variable DC link. Overall, the operation of UPQC interfaced with NLMLI is effective over D-STATCOM in alleviatin g harmonics, DC-offsets, and voltage-current imbalances during faulted conditions. The accurateness of simulation results and their comparative analysis is found to be satisfactory. © 2021 Elsevier Ltd