Research On The Control Problems Of Single-phase Energy Feedback Analog Load For Microgrid

Microgrid requires all kinds of high power load in operation and debugging. The traditional load of resistance, capacitance or inductance has energy loss. To save energy, single phase energy feedback analog load for Microgrid is studied and has important practical significance and application value.According to the actual situation of the microgrid laboratory in liaoning university of technology, the capacity and main circuit topology of two-level PWM converter are selected. Based on the system capacity, speed of response, allowing harmonic requirement and the modulation method, the parameters of capacitance and inductance are designed.In order to realize load simulation and energy feedback, the cycle average model of voltage source PWM converter is set up, the control system of single-phase energy feedback analog load is designed. The PI is adopted to track the current of the constant impedance, constant power, constant current or nonlinear load by load simulation converter. The dual-loop control of voltage loop and current loop is adopted to track the feed net current by grid-connected converter. The simulation circuit is built and verified in the MATLAB/Simulink software. The result shows that this model can complete the basic functions, but also have three problems that the current tracking accuracy is not enough, the grid current harmonics and inrush current to be solved.The combination of repetitive control and P control is adopted to solve the current tracking accuracy and proved to be effective through the simulation. The low pass filter is designed to solve the grid current harmonic and proved to be effective through the simulation. A new method is that the input of load simulation converter is small power and grid-connected converter does not work at the starting and the input of load simulation converter is devises under test and grid-connected converter start to work when the DC bus voltage is charged to the working voltage. The method is proposed to solve the inrush current and proved to be effective through the simulation.