Fault current-limiting control method and device for photovoltaic grid-forming system

A fault current-limiting control method for a photovoltaic grid-forming system, comprising:

• acquiring a voltage of a capacitor on an input side of an inverter in the photovoltaic grid-forming system;
• generating a switch transistor control signal based on the voltage of the capacitor on the input side of the inverter;
• acquiring a voltage signal and a current signal of a converter at a common-coupling point in the photovoltaic grid-forming system;
• obtaining a voltage amplitude of the common-coupling point and a voltage signal and a current signal in a stationary synchronous frame system based on the voltage signal and the current signal of the converter at the common-coupling point;
• determining a fault depth based on the voltage amplitude of the common-coupling point, and determining an active power reference of the inverter based on the fault depth;
• generating a voltage reference value and a phase reference value of the inverter based on the voltage signal and the current signal in the stationary synchronous frame system and the active power reference of the inverter;
• converting the voltage reference value and the phase reference value of the inverter into a current reference value through fixed virtual impedance;
• and
• obtaining an inverter modulating wave based on the current reference value, and obtaining a control signal of each switch transistor of the inverter after the inverter modulating wave is modulated by Sinusoidal Pulse Width Modulation (SPWM).