Research On Control Technology Of 500kW Power Conversion System

In order to solve the energy crisis and the serious problem of the traditional energy sources, an increasing attention has been paid on the development and application of the distributed power supply of wind energy and solar energy. With the rapid development of China’s economy, the distributed power is deeply and widely developed, which is mostly used to constructs a flexible micro-grid. It is an effect way to solve the problem of energy crisis by making full use of the renewable energy to generate electricity. But with the increase of renewable energy power generation and power grid access rate, the volatility and uncertainty of the intermittent energy resources have brought great challenges to the stable operation of power grid.As an important part of the micro grid, Energy storage system is essential for stable operation of the micro grid in restraining power fluctuations, cutting peak and filling valley of the power, stabilizing voltage and improving the power quality of micro grid. High power conversion system (PCS) is used as the interface of the energy storage device and micro grid to realize the bidirectional flow of energy. In this paper, the energy storage converter in the micro grid application is studied, and the control of energy storage battery and the method of energy scheduling are mainly studied.The storage battery is an important part of the whole storage system. Firstly, the cell types and their respective characteristics are enumerated, and then this paper analyzes the battery charge and discharge theory basis and operation characteristics of the battery. At last, the paper introduces the current energy storage battery charging methods commonly used, and then to determine the charge and discharge control strategy that the system uses.An accurate mathematical model is the basis for the derivation of the control strategy. Firstly, the working principle of PWM converter analysis, switch function, derived from the switching function model based on is introduced, and then the average operator obtains the cycle switch average model, finally taking advantage of the small signal perturbation method, DC operating point near the AC small signal model, which lays the mathematical foundation for deduction of PWM converter control strategy.On the basis of the mathematical model, the final control strategy is obtained according to the control objectives. Control strategy is divided into three parts:the first part is the DC energy storage battery control; the second part is control of grid connected AC side. The third part is the under different load condition according to the setting of grid distribution instruction. Through the automatic power distribution control method, the balance of power in the whole micro grid can be realized, and the power quality of the grid connected current can be guaranteed. Finally, the control strategy is verified by the Matlab/Simulink simulation and the semi physical simulation platform based on APPSIM.Based on the model of Matlab/Simulink simulation, the hardware in the loop simulation platform based on APPSIM software is used to verify the control strategy proposed in this paper. Finally, the simulation results are analyzed, which verifies the effectiveness and correctness of the control strategy.