Research On Control Strategy Of Power Conversion System In Distributed New Energy Power Generation

As an important clean energy,distributed wind power and photovoltaics generation accounts for an increasing proportion of the energy network,but due to its own limitations,direct grid connection will have an impact on the grid,so energy storage converters have emerged.Through the coordinated operation of multiple energy storage units in the power grid,the power fluctuations caused by environmental factors of clean energy can be suppressed,and the stability of the bus voltage can be maintained while ensuring the reasonable load distribution.In this paper,based on the control strategy of virtual synchronous machine,the energy storage converter is studied,and the power distribution problem based on the loss of different energy storage systems in the multi-source parallel scenario is analyzed in depth.First,introduce conventional energy storage converter control technology,including PQ control,V-f control and Droop control,is introduced.Because traditional control technology cannot solve the shortcomings of low inertia and no damping of the inverter circuit,VSG control technology has become a research hotspot.This article introduces the working principle and vector control of the wind turbine,establishes the doubly-fed wind turbine model,wind turbine converter model and energy storage system model,and analyzes the working principle of the bidirectional DC-DC converter.Secondly,in order to reduce the impact of conventional power conversion system operation on system stability,this paper adopts a PCS-based virtual synchronous generator VSG control strategy.According to the control target of the virtual synchronous generator,the active power control loop and the reactive power control loop are designed,and the virtual synchronous generator is simulated and analyzed for off-grid and grid-connected to verify the effectiveness of the virtual synchronous generator control strategy.The doubly-fed wind generator is simulated,its output characteristics are studied,and it is simulated online with an energy storage converter under the control of a virtual synchronous generator.Research on the parallel coordinated control scheme of traditional energy storage converters,and put forward the shortcomings of the traditional scheme.The droop coefficient is adjusted for different load conditions,and the virtual impedance method is used to achieve the same line impedance between each converter and the public AC bus,so as to reduce the impact of different line impedances on the coordinated control of the multi-converter system.Perform simulation experiments on energy storage batteries,study the differences in SOC curves of different energy storage batteries,and propose a power distribution optimization scheme based on changes in the SOC curve of energy storage batteries,so that the distribution of power between the converters is based on the voltage of the energy storage battery terminal.Finally,based on the theoretical analysis and research of different component modules,a control logic framework for system operation is constructed,and a simulation model is built in Matlab/Simulink,the designed simulation circuit is tested,and the experimental results are analyzed and summarized.The results show the correctness of the built model and the effectiveness of the control strategy.