Research On Control Technology Of PV And Energy Storage Power Generation System Based On VSM

With the large-scale distributed power supply connected to the grid potentially adverse impact to the grid,intermittent and volatility of renewable energy has brought great impact to the grid,affecting the stability of the grid voltage and frequency.This paper takes photovoltaic power generation system as the research object,adding an energy storage system on the photovoltaic output side,and using virtual synchronous machine technology to control grid-connected inverters.On the one hand,it can solve the intermittent and volatility problems of photovoltaic power generation systems,and on the other hand,the system It has inertia and damping characteristics similar to a synchronous generator,participates in the frequency and voltage regulation of the power grid,and improves the friendliness of renewable energy power generation and grid connection.In this paper,a virtual synchronous machine and its inverter control model are first established.According to the second-order classic model of the virtual synchronous machine,a virtual power frequency controller and a virtual excitation controller are designed to simulate the output characteristics of the synchronous generator,and the virtual rotor algorithm the structure is improved.For the voltage and current double closed-loop control of the grid-connected inverter,the voltage loop uses a PI controller to improve the voltage control accuracy,and the current loop uses a proportional controller to improve the current tracking speed.Then,an overall model of photovoltaic and energy storage systems was established,including photovoltaic cells,photovoltaic DC/DC,energy storage batteries and energy storage DC/DC.The photovoltaic MPPT control adopts the disturbance observation method,and the energy storage DC/DC adopts voltage and current double closed loop maintenance.The bus voltage is constant,and the photovoltaic storage system adopts a two-stage structure with a common DC bus.The photovoltaic energy storage coordinated control strategy is designed.Through the simulation of light changes,the simulation verifies the effectiveness of the proposed photovoltaic energy storage coordinated control strategy.It also simulates system power command changes,voltage frequency changes,and load mutations to verify the operating reliability of the optical storage virtual synchronous machine system in grid-connected and isolated gridconnected modes.By analyzing the influence of the moment of inertia J and the damping coefficient D on the response characteristics of the system,a virtual moment of inertia adaptive control strategy is proposed to flexibly change the value of the virtual moment of inertia J.Starting from the energy storage side,considering the battery’s state of charge and charge and discharge power constraints,as well as the frequency change rate and damping ratio constraints,the virtual synchronous machine operating parameter selection boundary is studied,and the proposed control strategy and parameter boundary are verified through simulation.Validity and correctness.Finally,considering that the resistance of the line in low-voltage transmission cannot be ignored,the coupling of active power and reactive power of virtual synchronous machines and the circulation problems of multiple machines in parallel are analyzed.The virtual impedance method is used to improve the resistance-toinductance ratio of the transmission line,so that the sum of the equivalent output impedance of the virtual synchronous machine and the line impedance is approximately purely inductive,and power decoupling is realized.Based on the virtual impedance method,the active power and reactive power distribution strategy of the virtual synchronous machine multi-machine parallel system is studied,and the correctness and effectiveness of the power distribution strategy are verified by simulation.There are 109 figures,5 charts,and 94 references in the thesis.