A Differential Protection Method Against Abnormally Large Number of Sampling Values

Abstract

The invention provides a differential protection method for preventing abnormally great number of sampling values. The differential protection method includes steps of starting sudden change of current or current effective value when abnormally great number of sampling values of a device to be protected is generated; after starting protection, waiting for a cycle of data, and starting allowance criteria if the abnormally great number of the sampling values in one cycle is continuously or intermittently generated and data calculated by full-cycle Fourier algorithm satisfy action criteria. The differential protection method is applicable to various differential protections such as differential protection of transformer and other quick-break actions, and the problem that misoperation of the protection device is caused by abnormalities of the sampling value of a data acquisition system of the protection device when electromagnetic interference occurs at the mounting position of the protection device or hardware of the protection device is abnormal is avoided.

Description

technical field [0001] The invention relates to a method in the technical field of electric power system relay protection, in particular to a differential protection method for preventing abnormally large sampling values. Background technique [0002] The current differential protection principle is the most ideal relay protection principle. Differential protection regards the protected device as a node, and the currents flowing into and out of the protected device are equal in normal conditions, and its differential current is equal to zero; when the protected device fails, the two currents are not equal, and the differential current is greater than zero ; When the differential current is greater than the setting value of the differential protection device, the protection outlet will act, and the circuit breakers on each side of the protected equipment will trip, so that the faulty equipment will be disconnected from the power supply. [0003] The principle of differential...

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Problems solved by technology

[0004] However, there are electromagnetic interference problems on the site where the protection device is installed, and the hardware of the protection device is often abnormal, which leads to abnormal sampling values ​​in the data acquisition system. When the current sampling values ​​are continuously or intermittently large, it will cause differential protection to malfunction. , a serious threat to power grid security

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