Research on Reactive Power Compensation and Harmonic Elimination Based on Current Predictive Control Method

As more and more photovoltaic power stations and wind farms are connected to the urban distribution network, the power quality problems that they caused are also becoming more and more prominent. Renewable energy power generation systems are connected to distribution networks through power electronic conversion devices, which bring a lot of harmonic problems to the power grid. In addition, the power electronic device consumes a certain amount of reactive power in the process of work, which leads to the insufficient of reactive power, and causes the voltage drop at the end of the transmission line. As a result, the power quality problems are seriously affecting the normal power consumption of users. In order to solve the problems of harmonics and reactive power brought by renewable energy systems, a compensation method based on current prediction control strategy is proposed in this paper. Firstly, a discrete-time model of the three-phase four-leg inverter is developed in synchronous reference frame. Then, the controller uses all the possible switching states of the inverter for the prediction and evaluates them using a cost function. The switching state, which minimizes the cost function, is then chosen and applied at the next sampling interval. Finally, theoretical analysis and simulation results show that the proposed method can realize reactive power compensation and harmonic elimination of distribution network.