Zero sequence voltage detection method for voltage transformer

Abstract

The invention provides a zero sequence voltage detection method for a voltage transformer. The zero sequence voltage detection method comprises the steps of including three opening triangle windings and measuring windings at the secondary side of a voltage transformer, and adding three-phase AC voltage U square root 3 with equal phase and equal amplitude to the three phase of a measuring winding terminal row (the voltage phase of the three phase is zero); observing the value of an analog zero sequence voltage through a display screen of a protection device, connected to the opening triangle winding; observing the value ULN of the analog zero sequence voltage through an AC voltmeter connected to the opening triangle winding and a neutral point N, if the protection device is of an electromagnetic type; determining whether it is abnormal based on U square root 3 and ULN. The zero sequence voltage detection method for a voltage transformer is advantageous in that the whole process of generating zero sequence voltage can be correctly simulated; whether the loop of each winding is defected or not can be accurately detected without disassembling the secondary terminal line of the voltage transformer; the time for the whole test is very short.

Description

technical field [0001] The invention belongs to the field of relay protection, and specifically relates to a zero-sequence voltage detection method of a voltage transformer. Background technique [0002] In the small current grounding system, the function of the voltage transformer is metering, monitoring and relay protection. Among them, whether the open delta winding generates zero-sequence voltage is an important basis for judging the grounding and disconnection of the primary line, and plays the role of relay protection. [0003] In the traditional relay protection test, it is quite troublesome to disassemble and calibrate the secondary line of the voltage transformer, and then simply add a protection constant value voltage to the relay coil to make the relay operate, even if the zero sequence voltage (grounding protection) is completed Experiments, but did not correctly simulate the whole process of zero-sequence voltage generation based on the principle of electromagn...

AI Technical Summary

Problems solved by technology

Therefore, the disadvantages and deficiencies of this test method are obvious: one is to disassemble the secondary line end of the voltage transformer to calibrate the line, the time for dismantling and restoring the terminal line is longer and error-prone; the other is that it is impossible to verify zero Third, it is impossible to verify the mutual ratio relationship between the measurement winding and the open delta winding; Fourth, it is impossible to verify the internal connection mode of the open delta winding; Fifth, it is impossible to verify whether the outlet end of the open delta winding is connected to the external protection device Complete and correct; Sixth, it is impossible to verify whether there are defects inside each winding

Images