Research On Tracking Technology Of Photovoltaic Reserve Capacity Based On Virtual Synchronous Generator

At present,photovoltaic(PV)power generation play an increasingly important role in power system due to the rapid growth of PV.They are composed of power electronic inverters,therefore,the design of grid-connected inverter feeding units has become main problem in the field of power grid control.In order to improve the stability of microgrid system and make efficient use of PV,the PV reserve capacity tracking technology based on Virtual Synchronous Generator is studied.First of all,the paper introduces the idea of source control of PV power system,and the PV arrays are designed by series-parallel PV power generation units;describes the proposed maximum power point tracking strategy with reserve capacity,qualitatively and quantitatively analyzes the PV power supply stable operation area,and tracks the stable operation point of MPPT strategy using curve implicit fitting method.This method ensures rapid switching of standby capacity when load demand increases,thus completing the flexible operation of reserved spare capacity.Simulation verifies correctness of the theoretical analysis and the proposed strategy.Then,with the help of Lyapunov's stability criterion,a new VSG control strategy with boundary condition is proposed to keep the frequency and voltage stability within the allowable range of rated,so as to ensure the stability of closed-loop power system.The simulation results show that the poposed strategy can make the grid-connected inverter maintain the power droop characteristic similar to that of the traditional synchronous generator during normal operation of grid,and guarantee the angular frequency and excitation current balance point of stability and convergence during abnormal of grid,which can ensure that the frequency and voltage fluctuations remain within the allowable range all the time.Finally,an additional control model of PV power has been established,so that the active output tracks load demand in real time;the PV reserve capacity tracking technology based on the new VSG control is proposed by rational design of LCL filter parameters and effective combination of the maximum power point tracking method with the reserve capacity and the new VSG control strategy with boundary conditions.Simulation was performed with MATLAB/Simulink.