Design And Application Of Electric Spring

Since the depletion of traditional energy sources and the environmental problems caused by them,the penetration rate of new energy sources such as wind energy and solar energy is gradually increasing,and the grid-connected scale of new energy power generation is gradually increasing.However,the intermittent and unstable problems of new energy power generation will cause fluctuations and flicker in the grid voltage,resulting in different degrees of instability of the grid.For voltage fluctuations,large grids have a certain degree of self-adjustment,while small microgrids have relatively poor adjustment capabilities.In response to this situation,the Shu Yuen(Ron)Hui team of the University of Hong Kong proposed the power spring as a new type of power electronic device.The ES can effectively suppress the voltage fluctuation caused by the distributed power generation variation.Firstly,this thesis introduces the research background significance of this topic and the research status at home and abroad.Through the definition of electric spring and the analysis of circuit topology,the working principle of electric spring under direct power supply and grid-connected power supply of new energy is studied:When fluctuations occur,voltage fluctuations are transmitted to non-critical loads to stabilize critical load voltages,providing a good environment for the normal operation of critical loads.Secondly,based on the ES circuit topology diagram,a mathematical model is built.Based on the power spring based on PI control,combined with the optimized immune genetic algorithm,the optimal PI parameters suitable for the control system are found,thereby improving the voltage regulation capability and stability of the electric spring.Then the factors affecting the ES critical load regulation are studied.According to the derived mathematical model formula,the non-critical load resistance,the inductance and capacitance of the LC filter in the power spring,the impedance of the transmission line,and the grid frequency of the grid transmission are analyzed.The effect on the stability of critical load voltages.Then the application of ES in the microgrid is studiedFinally,using the Matlab/Simulink simulation test platform,the power spring voltage control method proposed above and the parameters affecting the critical load voltage are simulated and analyzed.The test results verify the feasibility and effectiveness of the voltage regulation control method,and the range of voltage fluctuations that the power spring can suppress when the parameters change.Then,using the computer-aided design of the electromagnetic transient function module of the power system,it is verified that the electric spring can reduce the voltage fluctuation caused by the wind speed fluctuation under the change of wind speed.