Case studies for load compensation using RSDCHBMLI based DSTATCOM using predictive current control

Abstract

In this paper, the load compensation performance of a distribution static compensator connected to a non-stiff distribution network is presented under different conditions of loading and source voltages. The DSTATCOM is implemented using a reduced switch single DC-source based cascaded H-bridge multilevel inverter (RSDCHBMLI). RSDCHBMLI overcomes the problem of high power rating of the switches required for a two level inverter along with providing inherent isolation and a lower component count as compared to other popular multilevel inverter (MLI) topologies. The usage of single DC-bus capacitor in RSDCHBMLI eliminates the need of additional circuits or controls for voltage balancing among them, which is a major drawback of other MLI topologies. In this paper, the voltage control of the DC-bus capacitor is achieved using a current based controller which permits direct calculation of the PI controller gains. The DSTATCOM is operated using finite control set model predictive control (FCS-MPC) algorithm which ensures balanced and sinusoidal source currents along with maintaining a distortion free PCC voltages. The performance of the DSTATCOM is investigated under different conditions of linear and nonlinear loads, with balanced and unbalanced sources.