Research and application of the detection technology of low voltage photovoltaic grid-connected circuit breaker

Low-voltage photovoltaic grid-connected circuit breaker is the key equipment for distributed photovoltaic grid-connected power generation system to connect to the power distribution network. Its function and performance determine the normal grid-connected operation of the system and the quality of power supply. Due to the lack of professional detection tools, this paper studies its test technology. This paper analyzes the characteristics and functions of photovoltaic grid-connected circuit breakers and puts forward the test requirements. According to the requirements, the overall design scheme of the detection system is proposed, and the solutions of several key detection technologies are put forward, including: the voltage and current output technology of "same line but different loop" is proposed to achieve the accurate output of the amplitude and phase of the current and voltage in a large range; the residual current equivalence test technology is proposed to realize the high precision and high efficiency detection of residual current; the voltage power source is developed to support the step change of the output amplitude, phase, frequency and harmonics, so as to realize the simulation of the electrical quantity when the islanding effect occurs, and verify the islanding protection function; a closed-loop automatic detection technique is proposed to realize the highly effective automatic test of low-voltage photovoltaic grid-connected circuit breakers.