Research on Current Predictive Control Method for Three-phase Four-leg D-STATCOM

In order to solve the three-phase currents imbalance and harmonic pollution problems in distribution network, a compensation method based on the current predictive control is presented in this paper. In this paper, the instantaneous reactive power theory is used to calculate the compensation current. Then the current predictive control is applied in the D-STATCOM. Firstly, the discrete-time model of D-STATCOM is built, in which the traversal method is used to evaluate the output voltage of compensator in all switching states, and the optimal switching combination is chosen by using suitable cost function. Then the compensating current is rapidly outputted according to its reference value. In the end, simulations are carried out on the PSCAD/EMTDC platform, based on proposed control strategy, the reactive power compensation and harmonic elimination have been studied under such cases as unbalanced reactive load and input harmonic in three-phase four-wire system. The simulation results show that the proposed method can achieve rapid reactive power compensation and harmonic elimination.