Judgment method of line breakage of special TV for inter-turn protection of generator

Abstract

A judgment method of line breakage of a special TV for inter-turn protection of a generator comprises the following steps: a generator terminal is provided with a general voltage transformer TV1 and aspecial voltage transformer TV2 for inter-turn protection; a protection device is used for sampling secondary side voltages of the voltage transformers, thus respectively obtaining negative sequencevoltage 3U2 of the TV1, negative sequence voltage 3U2' and foundational wave zero sequence voltage 3U0' of the TV2 based on holocycle Fourier filtering and calculation; and fixed values U2.set1, U2.set2 and U0.set2 are preset inside the protection device, wherein, 3U2 is smaller than U2.set1(1), 3U2' is greater than U2.set2 (2) and 3U0' is greater than U0.set2 (3). When meeting inequations (1)-(3)simultaneously, a line breakage alarm signal of the TV2 is generated after short delay t1, and the inter-turn protection is locked; and if the TV2 has no line breakage later, that is, that is, the inequations (1)-(3) can not be met simultaneously, line breakage alarm of the TV2 is canceled after long delay t2, and longitudinal fundamental wave zero voltage inter-turn protection is re-started.

Description

technical field [0001] The invention relates to a method for judging the disconnection of a voltage transformer dedicated for inter-turn protection of a generator, which is used to prevent malfunction of the inter-turn protection of the longitudinal fundamental wave zero-sequence voltage of the generator, and a protection device using the method. Background technique [0002] Large-scale generators are equipped with voltage transformers (TV) at the machine end to monitor the voltage output of the generator during operation. Most of the steam turbine generators, gas turbine generators and nuclear power generators are installed A special TV for inter-turn protection is installed at the end. The three-phase windings on the primary side of the special TV are connected in star form, and the neutral point is directly connected to the neutral point of the generator through a high-voltage insulated cable. Open triangle connection is adopted. Through a dedicated TV, the three-phase...

AI Technical Summary

Problems solved by technology

In the former method, when the generator is running at no load, there is no current at the machine terminal, and there is no current signal at the machine terminal TA, so the negative sequence current cannot be calculated, and effective judgment cannot be made

The latter method only recognizes that the TV is disconnected, and does not distinguish whether it is a dedicated TV disconnection or a conventional TV disconnection. It needs to be further judged by combining the positive sequence voltage or negative sequence voltage of the TV, which is a bit complicated.

Images