Photovoltaic Based On Virtual Motor Research On Grid-Connected Control System Of Power Generation

Solar energy has the characteristics of renewability and non-pollution,so it provides a idea for solving the increasingly prominent energy and environmental problems.The traditional control strategy of grid-connected photovoltaic inverter control system is replicated in topology structure,which is too expensive and vulnerable to power grid frequency fluctuations.This paper presents a control strategy of grid-connected photovoltaic inverters based on virtual motors.Taking the whole photovoltaic grid-connected system as the research object,the main technologies such as photovoltaic cell characteristics,maximum power point tracking,virtual motor characteristics and control strategy of photovoltaic inverters are analyzed theoretically.The design method of relevant parameters and the model structure are given.Finally,the effectiveness of the proposed control strategy is verified by numerical simulation and experiment.The stable DC voltage is the basic condition for the stable operation of the system.In this paper,a photovoltaic array power generation system is built based on the characteristics of photovoltaic cells,and the maximum power tracking control strategy is realized by using perturbation observation method.At the same time,in order to stabilize the DC side output voltage,a battery model is added to stabilize the DC side voltage by utilizing its bidirectional charging characteristics.The simulation results show that the output DC voltage has good dynamic and steady-state performance against external environmental interference.The realization of inverter control strategy in grid-connected photovoltaic systerm is the key condition for the stable operation of the system.Firstly,the theory and principle of traditional direct power control are analyzed,and the shortcomings of its control strategy are further explored,such as complex topology and susceptibility to interference.On this basis,the concept of virtual motor is put forward,and the principle of optimization and improvement of direct power control method for Inverters Based on virtual motor characteristics is studied and expounded.Finally,the system model is built and tested on the simulation software.and the simulation results prove the effectiveness of the proposed control strategy.Based on the above theoretical research and simulation analysis,an experimental platform is built to verify the proposed control strategy and model.The experimental platform uses the DSP chip of model TMS320F28335 as the controller,and the capacity of photovoltaic inverters is 5 kW.Firstly,the different modules are tested separately,and then the control modules are transplanted to the DSP to realize the overall control of the photovoltaic grid-connected system using the DSP.The control module includes maximum power point tracking,PI control,virtual torque calculation,virtual flux observation and so on.The experimental results show that the PV grid-connected inverter control system based on virtual motor can achieve the goal of voltage stability control on DC side and ensure the quality of AC output power.At the same time,it can restrain the power grid frequency interference and ensure the normal and stable operation of the whole PV grid-connected system.