Motor differential protection method based on optical fiber communication

Abstract

The invention provides a motor differential protection method based on optical fiber communication. The motor differential protection method comprises the step that a far-end acquisition unit in a distributed differential protection network system autonomously completes sampling synchronization with a differential protection main device through communication exchange with the protection main device. Through sampling clock synchronization between the far-end acquisition unit and the protection main device, distributed synchronous acquisition of motor tail-end data is realized. By means of the high-speed and large-capacity data transmission capacity of the Ethernet, protection original data synchronously collected at the far end are rapidly and completely transmitted to the differential protection main device, complete differential protection data are constructed by the protection main device, and the high-precision and rapid longitudinal differential function is achieved. According to the distributed differential protection communication network for the motor, an optical fiber Ethernet is adopted, an external clock source is not needed, the differential protection main device is a main clock source, the far-end acquisition unit is a slave clock device, and the distributed far-end acquisition unit autonomously realizes sampling clock synchronization with the protection main device.

Description

technical field [0001] The invention relates to the technical fields of relay protection and automation of power systems, in particular to a method for differential protection of electric motors based on optical fiber communication. Background technique [0002] The basic principle of current differential protection is based on Kirchhoff's current law. It can ideally realize the unitization of protection. The principle is simple, the response is sensitive, and it is not affected by the change of operation mode. It is widely used on lines and buses, and has the advantages of high sensitivity, simple, reliable and fast action, and can adapt to various operating modes of the power system. The incomparable advantages of current differential protection in other forms of protection make it widely used in the main protection of large motors. The traditional differential protection of motors is through the centralized differential protection device arranged on the power switch side ...

AI Technical Summary

Problems solved by technology

The currently used method of directly simulating the access to the motor to measure the CT current, due to the relatively large distance difference between the transformers at both ends and the installation of the protection device, makes the secondary impedance of the CTs on both sides seriously mismatch, and the linearity of the CT is affected. different, resulting in large deviations in the current data on both sides collected by the protection device during the change of the motor current, resulting in frequent occurrence of protection misoperation; In the selection, it is necessary to choose a large iron core transformer, which not only increases the system cost burden, but also affects the convenience of installation due to the large size of the large capacity CT

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