Research On Electric Spring Voltage And Frequency Control Method Applied To AC Microgrid

Electric spring is a new type of power electronic device used in power system,which changes the traditional way of determining the amount of electricity generated by electricity demand in the power system,realizes that electricity consumption can change with the amount of power generation,and effectively alleviates the intermittent and unstable problems of new energy generation such as solar energy and wind energy.In the current study,electric spring is mainly used to solve the problem of bus voltage fluctuation caused by new energy generation in distribution network.But the control method of electric spring participating in the system frequency adjustment while solving the voltage fluctuation problem is not complete.This paper studies the electric spring applied to AC microgrids.The main research work is as follows:(1)At first,The topology of single-phase and three-phase electric springs is summarized and the capacitive electric spring is selected as the research object.A mathematical model of single-phase electric spring is established,and the relationship between the active power of the system and the critical load voltage is derived.(2)The control method of electric spring is studied.The single-degree-of-freedom control method based on amplitude-phase angle constraint and virtual capacitance control method are proposed for single-phase electric spring.The method of single-degree-of-freedom control based on amplitude-phase angle constraint is extended to the three-phase.A frequency-regulation control method applied to a three-phase electric spring is proposed.(3)A frequency-voltage optimization method based on electric spring is proposed for the high-permeability AC microgrid system of renewable energy.The influence of the electric spring permeability on the frequency stability of the microgrid system with multiple electric springs is analyzed.(4)Finally,according to the above theoretical analysis,the corresponding simulation model is built in the PSCAD simulation software,and the obtained analysis results are verified by simulation,which proves the correctness of the theoretical analysis conclusion and the effectiveness of the proposed method.In this paper,a control method that can stabilize the voltage and participate in the system frequency adjustment is proposed for the electric spring.The voltage and frequency fluctuation of the AC microgrid system with high permeability of renewable energy is solved.