Research On Control Strategies Of Energy Storage Inverter

In order to improve the reliability and safety of the power grid, and mitigate the problem of the resource shortage and environmental issues caused by the traditional power electronic system, the micro grid has been widespread concerned and researched. It has flexible configuration and the operation is convenient. The energy storage inverter is the key conversion device of the micro grid system, which plays an important role in regulating the surplus and deficiency of the electricity between the storage battery and the grid. The key technology of the energy storage inverter is its control strategies, which will effect the p ower quality and the control effect of the voltages and currents of the system. Therefore, the research on control strategies of energy storage inverter is of great significance.This dissertation introduces the bi-directional flow principle and the topological structure, and on this basis we establish the mathematical model working in energy invertion situation and energy storage invertion, respectively. We discuss the control structure and control strategies in these two working conditions. When working in energy invertion situation, we use the current single loop control structure to simplify the analysis and guarantee the currents meet the requirements. When working in energy storage situation, the double loop control structure is adopted to make both currents and voltages stable. This dissertation analyses the traditional proportional-integral( PI) control strategies used in energy storage inverter. As the loop resistance may changes, and the situation of nonlinearity and disturbance are complicated, the traditional PI control can not guarantee the stability and robustness within the large range. Therefore, we adopt the passivity-based control and the active disturbance rejection control technologies to current and voltage loops control.To verify the control effects of the control strategies, the model of the system and controllers under the Matlab/Simulink environment are established. This dissertation analyses the PBC scheme in energy invertion situation and make a comparison with the PI control. In energy storage situation, the combination of passivity-based control scheme and active disturbance rejection control are compared with PI double loop control and the combination of passivity-based control and PI control. By simulating in Matlab/Simulink, the passivity-based control scheme can make the current tracking to the setting point with no ste ady state error, and have good robustness to the resistance. When using the active disturbance rejection voltage loop control, the voltage can reach the reference value with the fastest speed, and have good capacity of resisting disturbance.