Photovoltaic grid-connected inverter insulation resistance detecting method and detecting device for implementing same

Abstract

The invention discloses a grid-connected inverter insulation resistance detecting method. The method aims at solving the problem of multi-way input photovoltaic grid-connected inverter insulation resistance detection, unbalanced bridges are established in a main circuit, a series of circuit equations are generated by detecting changes of the input voltage, an equation set formed by all the equation is solved in the end, and insulation against ground resistance input by each circuit are obtained. The invention further discloses a detecting device for implementing the photovoltaic grid-connected inverter insulation resistance detecting method. Compared with the prior art, the detecting device can carry out accurate measurement on the insulation against ground resistance of each input end of a multi-way input photovoltaic grid-connected inverter, and therefore defects of insulation resistance can be found before hand on the premise that grid-connection exists, and the safety and reliability of grid-connected operation of the photovoltaic grid-connected inverter can be improved; meanwhile, the circuit for implementing the method is simple in structure, easy to achieve, and low in cost.

Description

technical field [0001] The invention relates to a method for detecting insulation resistance of a photovoltaic grid-connected inverter, in particular to a method capable of detecting the insulation resistance of a photovoltaic grid-connected inverter with multiple inputs. Background technique [0002] In the photovoltaic grid-connected standards of many countries, there are regulations on the insulation resistance of non-isolated photovoltaic grid-connected inverters, which require that the insulation resistance of the positive and negative terminals connected to the photovoltaic input of the inverter to the chassis (earth) is not less than the specified Therefore, it is very necessary to add insulation resistance detection to non-isolated grid-connected inverters. At present, the insulation resistance of photovoltaic grid-connected inverters is mostly detected by the method of bus voltage division to detect the insulation resistance of single input to ground, that is, there...

AI Technical Summary

Problems solved by technology

At present, the insulation resistance of photovoltaic grid-connected inverters is mostly detected by the method of busbar voltage division to detect the insulation resistance of single input to ground, that is, there are two unknown impedances, which is relatively simple

For a multi-input photovoltaic system, the number of input channels is large, and there are relatively many unknown impedances. It is impossible to simultaneously detect the insulation resistance of each input to ground in the multi-channel photovoltaic input through a simple resistance ratio.

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