Study on the inverter performance of a new sliding mode phase-locked loop in VSG of photovoltaic system
In order to study the performance of inverters under unbalanced voltage in photovoltaic systems,a new reaching law sliding mode control phase-locked loop is introduced on the basis of virtual synchronous generator control.Firstly,the new sliding mode phase-locked loop is used in the virtual synchronous generator to regulate the positive sequence components of the voltage separated from the decoupled dual synchronous reference coordinate system;then,the positive and negative sequence components of the voltage and the current are separated using the decoupled dual synchronous reference coordinate system and the symmetric component method respectively;and then they are individually controlled and generated as voltage modulated signals.Simulation results show that the phase-locking error of the new sliding mode phase-locked loop are only 0.019 7 and 2.401 5×10-10,which are much smaller than 1.485 3 and 1.640 5 of the decoupled double synchronous phase-locked loop,when the grid voltage drops and the phase jumps occur.The introduction of a new sliding mode phase-locked loop can enhance the stability and robustness of the system and improve the operational performance of PV inverters under voltage imbalance conditions,which provides a certain reference for the design and optimization of PV system inverters.
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