Series arc fault positioning device and method under condition of parallel connection of multiple photovoltaic branches

Abstract

The invention discloses a series arc fault positioning device and method under the condition of parallel connection of multiple photovoltaic branches, and the method comprises the steps: constructing a unified mathematical model of the output characteristics of a photovoltaic group string, substituting a current sampling value of each photovoltaic branch into a mathematical expression, and calculating the output total voltage of all assemblies in the photovoltaic branch; subtracting the total output voltage of components in each branch from the direct current side input voltage of an inverter to obtain a voltage difference value, and further calculating a power value and an energy value which reflect the intensity of the series arc of each branch according to the voltage difference value and the current value of each branch; when the power value is larger than a set threshold, judging whether an arc event occurs in the photovoltaic system according to the parallel loop common-mode current, further judging the grade and positioning of an arc fault according to the magnitude of the energy value, and sending a grading alarm signal to a photovoltaic power station monitoring system to ensure safe and stable operation of the photovoltaic system.

Description

technical field [0001] The invention relates to a device and method for locating a series arc fault in the case of parallel connection of multiple photovoltaic branches, belonging to the field of photovoltaic fault diagnosis. Background technique [0002] When an arc fault occurs in a photovoltaic power station, high temperatures will be generated when the arc continues to discharge, which will lead to fires and power outages. The UL 1699B standard provides the relationship between arc energy and fire risk. [0003] The existing photovoltaic system arc fault detection technology is mainly the loop current detection technology proposed for a single photovoltaic branch. Ensemble Empirical Mode Decomposition. In an actual photovoltaic power station, multiple photovoltaic branches are usually connected in parallel and then connected to the combiner box or inverter. When a series arc fault occurs in the photovoltaic branch, the loop current of the faulty branch will flow to the ...

AI Technical Summary

Problems solved by technology

[0004] The loop current detection technology has certain defects in the detection of series fault arcs. It is mainly reflected in the fact that it is susceptible to the high-frequency noise of the inverter switching tube. The characteristic frequency band of the fault arc overlaps with the high-frequency noise of the system, thereby interfering with the frequency domain characteristics. Identification results; on the other hand, whether the actual arc fault occurs at the DC bus or in the string, the existing detection technology fails to solve the problem of series arc fault location, which brings difficulties to the operation and maintenance personnel to troubleshoot the fault

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