Method and device for monitoring resistive current of voltage-limiting type surge protection device on line

Abstract

The invention discloses a method and a device for monitoring resistive current of a voltage-limiting type surge protection device on line. The method comprises the following steps: acquiring a surface temperature and total leakage current of a pressure-sensitive plate in the surge protection device and performing fast Fourier transform on the total leakage current to obtain total resistance current; calculating the total resistance current to obtain 1-7-order resistance harmonic current. The device comprises a voltage signal acquisition module, a current signal acquisition module, a dsPIC chip processing module, an output module and an external clock module, wherein the voltage signal acquisition module, the current signal acquisition module and the external clock module are connected with the dsPIC chip processing module through an A / D (analog to digital) conversion interface; the output module is connected with the dsPIC chip processing module. According to the method and the device, the problem of distinguishing and extracting on-line monitored current components can be effectively coordinated, the cost in production of the device for monitoring the voltage-limiting type SPD resistance current on line can be reduced, local network monitoring is convenient, and the conditions that an electrical fire or over voltage protection failure cannot be timely found due to SPD degradation can be effectively reduced.

Description

technical field [0001] The invention relates to the technical field of lightning prevention equipment, in particular to an on-line monitoring method and device for resistive current of a voltage-limiting surge protector. Background technique [0002] Surge protector (SPD) mainly uses shunt technology to quickly release pulse energy to limit the voltage amplitude on equipment and lines to achieve overvoltage protection. Its performance not only affects the safety of the entire power distribution system and communication system, It is also related to the economic benefits of operating the system. From the high-voltage system surge arresters that appeared in the 20th century to the current surge protectors for low-voltage circuits, the ultimate goal is to improve their shunt capacity. The types of existing surge protection devices mainly include switch type and voltage limiting type. The voltage limiting type surge protector uses zinc oxide as the main material. In the early 1...

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Problems solved by technology

Although the total leakage current method can reflect the defects of the overall damping of the arrester and the serious aging of the valve plate to a certain extent, because the resistive component accounts for a small proportion of the total leakage current (about 5% when it is degraded), it may be used as a resistance component. When the resistive current has increased a lot, the change of the total leakage current is still small, and the resistive current is often the main reason for the heating of the valve, so the sensitivity of this method is not high, and the collected data can only be used for the operation of the surge protector. In order to reduce the interference of capacitive currents, some experts and scholars mentioned in the paper "Testing Research on Surge Protectors Used in Lightning Protection Projects" that the meteorological department often Disassemble the surge protector and send it to the laboratory for offline testing. This detection method is time-consuming and labor-intensive, and cannot truly reflect the working status of the surge protector when it is working online; due to the inability to coordinate online monitoring and current component distinction For the problem of extraction, the double CT method and the temperature measurement method have been invented abroad to monitor the working status of the arrester. However, these two methods have certain advantages for the arrester monitoring of the high-voltage power transmission system, but for the low-voltage power distribution system , due to the complex structure of the power distribution network itself, many nodes, and a large number of surge protectors, it is economically impossible to use these two foreign methods

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