Research On Control Method Of Distributed Photovoltaic Grid-connected Inverter

As the consumption of traditional energy becoming higher and the problem of environmental pollution becoming more serious, to develop and use renewable green energy has become a research focus of governments and academics. Solar energy is considered as an ideal green energy, and its distributed photovoltaic generation technology is developing rapidly. As the core component of distributed PV system, the distributed grid-connected inverter is researched on its control method in this paper.First of all, the circuit structure of distributed photovoltaic grid-connected inverter is studied. According to the features of distributed generation systems, the basic topology type of the distributed inverter in this paper is determined, the working principle and applicable situation of different types of filter are also analyzed.Then, a new kind of inverter compound control method is proposed and designed in order to make distributed PV system connected to the grid with unit power factor. In photovoltaic grid-connected inverter, the problems of deadbeat control about current predict complexity and the control delay are discussed. When the means of beat control and control gain decrease are applied as the solutions to solve these two problems, the output current will have a phase lag behind the reference current. In order to solve the problem of phase lag, taking the phase lag as a kind of periodic disturbance, thus a beat control method with plug-in repetitive controller is further proposed, and the design process of the repetitive controller is given. Simulated results are given to illustrate the rationality and validity of the proposed method.Finally, the concrete applications of the proposed inverter control method for distributed PV system are studied and analyzed in order to illustrate the ability of the method in solving the special problems of distributed PV system. The control method of distributed photovoltaic grid-connected inverter should be able to solve its problems such as current compensation and cascaded operation. The research meanings of these two problems are discussed, and the feasibility of the beat control method with plug-in repetitive controller about these two aspects is studied. Based on the above control method, effective solutions are respectively proposed, then their simulation verifications are made, showing the applicability of the method when used in distributed system.