Research On Control Strategy Of Photovoltaic In Inverter Parallel System

From the beginning of the industrial revolution, the social economy has been booming, at the same time, human civilization has made great progress. The consumption of energy resources provides a strong driving force for the progress of social economy, and the final result of a large number of energy consumption is a serious environmental pollution. At present, one of the important ways to solve the problem of environmental pollution is to develop an energy substitute, and with environmental protection, no pollution, good economic benefits and other characteristics of the solar energy stand out. At present, the development of solar energy resources is mainly used for heating and power generation in two ways, among them, the most widely used is the photovoltaic power generation, so its development prospect is quite broad, however, the photovoltaic power generation process is the core of the device is the inverter, Its energy conversion efficiency determines the whole power generation process. The effective response to large power and redundant power supply requirements is the parallel operation of several inverters, so it is regarded as the main direction of the current inverter technology progress. According to the principle of whether there is interconnection line, the classification of parallel system is divided as two kinds of parallel connection and parallel connection.There is a connection between each inverter is connected to the communication between the lines, however, there is no such kind of communication link in parallel.and the trend of development in the future is the tendency of parallel connection. And for the control algorithm without interconnection, it is based on the principle of active power regulating frequency and reactive power regulating voltage in power system. The focus of this topic is photovoltaic inverter, particularly emphasised on the control mode and application of parallel inverters.This paper briefly describes the development of photovoltaic inverter and the necessity of parallel inverter, then the topology structure of the parallel system of inverter is built and the model is built, based on the modeling of parallel system, the control strategy of parallel system is developed, control strategies, such as master slave control, centralized control, decentralized logic control, and non interconnection control, are involved. Among them, the strategy is similar to the droop synchronous generator with flow characteristic droop performance of parallel inverter system, and the average current mutual connection does not exist between each inverter, But at the same time, it is a problem that the interaction between active power and reactive power is caused by the coupling of active power and reactive power. In view of this, in this paper, a new decoupling control strategy based on droop characteristic is considered, the basic principle of decoupling control and its application are described in detail, according to the mathematical model of decoupling control and the technical requirement of parallel operation of inverter, the corresponding hardware circuit and software program are designed.The simulation system of the system is constructed by combining with MATLAB/SIMULINK simulation software, at the same time, the system is modeled in the laboratory, in order to test the effect of the new decoupling control on parallel system, at the same time, the simulation and experiment results are analyzed carefully. Simulation and experimental results show that the inverter parallel system based on decoupling control has good current sharing capability, can meet the technical requirements of parallel operation of inverters.