Research on the Insulation Detection Technology of the AC Cable in Distributed Photovoltaic Power Station Considering Photovoltaic Inverter

The traditional insulation detection technology of the AC cable in power system which using AC voltage source, which cannot be applied to the power system using the DC voltage source in photovoltaic power station. At the same time, due to the nonlinear characteristics of power electronic components, it is difficult to find the fault criterion of the AC cable insulation in photovoltaic power station. This paper proposes an insulation detection mothed of AC cable based on the DC-signal injection method and considering the photovoltaic inverter. First, by establishing theoretical circuit model of the detection system, the calculation formula of the resistance of the AC cable insulation is deduced, and the signal extraction method is improved, an unbalanced bridge design is proposed to detect the DC-signal, which greatly improves the detection sensitivity and anti-interference. And then the simulation by using the MATLAB-Simulink verification shows that the method is effective. The influence of other parameter changes in the line on the accuracy of insulation detection is studied, which shows the applicability of this method.