Composite error test method and system for three-phase zero-sequence current sensor

Abstract

The invention discloses a composite error test method and system for a three-phase zero-sequence current sensor. According to the method, the rated primary current of a current sensor is determined to be 600A, the rated primary zero-sequence current of the current sensor is determined to be 20A, and the accurate value coefficient of the current sensor is determined to be 10 according to typical design parameters of the 10kV alternating current sensor of a power distribution network; by simulating a two-phase short circuit, when a composite error is carried out, the current passing through the zero-sequence current sensor is far less than 20A when the current not less than 6000A is introduced at one time; and the composite errors of the A phase, the B phase and the C phase of the three-phase zero sequence current sensor are respectively measured.

Description

technical field [0001] The present application relates to the technical field of electric power systems, in particular to a method and system for testing composite errors of three-phase zero-sequence current sensors. Background technique [0002] When a fault occurs in the distribution network, the primary short-circuit current is dozens of times the rated current. At this time, the current sensor should be able to accurately provide a large current signal to the distribution network terminal. The accuracy of the composite error of the current sensor is directly related to the relay Whether the protection device can operate correctly will affect the safety and stability of the distribution network system. Therefore, the composite error performance of the current sensor determines the reliability of the distribution network terminal relay protection. [0003] In the distribution network, a three-phase zero-sequence current sensor is generally used to measure the current of e...

AI Technical Summary

Problems solved by technology

According to the general requirements of the accuracy value coefficient of the current sensor, in the distribution network system, when performing the composite error test, the primary current passing through the current sensor reaches up to kA, at this time, the current passing through the zero-sequence magnetic flux is too large, reaching hundreds of times the rated primary zero-sequence current , will cause the zero-sequence iron core saturation sampling resistor current to be too high and be damaged

If the limit value of the three-phase rated primary current is applied, a large power source is required, and the unbalance of the three phases is guaranteed to be less than 1.5%, which brings high equipment investment.

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