Research on DC Bus Capacitance Health Status by Capacitance Temperature Voltage and Current of Photovoltaic Centralized Inverter

The photovoltaic centralized inverter is the core component of the photovoltaic power generation system, and its health status is critical to the output power quality. In PV inverter failures, more than half of the faults occur on the bus capacitor, and its capacity drop will increase the harmonic output, and the complete failure state will cause the power generation system to stop. The causes that affect the capacitor life are overvoltage, harmonic current, high temperature, etc. The inverter fault caused by the degradation of capacitor performance causes the operation of the photovoltaic power generation system to be interrupted, and the replacement and maintenance of the faulty module brings time and power generation benefit loss. Temperature is the main factor affecting the life of the capacitor, the temperature rise of the bus capacitor is mainly affected by the ripple current flowing through, the operating state of the inverter unit of the photovoltaic power generation system is changed with the uncontrollable photovoltaic input and AC bus bar, the temperature rise of the capacitor under different operating conditions, and the voltage and current output change of the capacitor capacitance under the same conditions, etc., analyze the relationship between the temperature rise of the capacitor and the operation and the relationship between the inverter output characteristics of the capacitance change, and provide theoretical support for the identification of the capacitor health state.