A fault detection method for grid-connected relays of photovoltaic inverters

Abstract

The invention discloses a fault detection method for a grid-connected relay of a photovoltaic inverter. The fault detection method comprises the following steps of sampling circuit detection, impedance grounding detection, and Relay contact impedance detection. At the step of sampling circuit detection, whether a grid voltage sampling circuit becomes abnormal is determined. At the step of impedance grounding detection, whether a live wire impedance grounding situation occurs is determined; if so, relay detection under the impedance grounding condition is carried out and thus relay abnormity detection under the live wire impedance grounding condition is carried out; and if not, relay detection under the non-impedance grounding condition is carried out to realize relay abnormity detection under the non-live wire impedance grounding condition. At the step of Relay contact impedance detection, whether the contact impedance of the relay is too large is detected. According to the invention,inverter grid-connected relay faults as well abnormal situations causing the grid-connected relay fault false reporting can be distinguished; and thus the fault cause can be located quickly and the machine can carry out grid connection reliably.

Description

technical field [0001] The invention relates to the field of grid-connected relays of photovoltaic inverters, in particular to a fault detection method for grid-connected relays of photovoltaic inverters. Background technique [0002] With the continuous development of the photovoltaic industry, the requirements for reliable and stable operation of photovoltaic power generation systems are getting higher and higher. In order to ensure that the photovoltaic inverter can be reliably disconnected from the grid at the moment of failure, the safety regulations generally require that the photovoltaic inverter has two sets of grid-connected relays in series. Before the inverter is connected to the grid, it is necessary to check whether the two sets of relays can be disconnected reliably and suction. At present, the conventional detection method only judges whether the grid-connected relay is normal by detecting the grid voltage and inverter voltage, and this method has a large bli...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the problem of false alarms of inverter grid-connected relays, the purpose of the present invention is to provide a fault detection method for photovoltaic inverter grid-connected relays, which can distinguish between inverter grid-connected relay faults and grid-connected relay fault false alarms Abnormal conditions, to ensure the rapid location of the cause of the fault and to ensure that the machine is reliably connected to the grid

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