Method for Determining DC Time Constant of Short-Circuit Fault Current at Generator Outlet

Abstract

The embodiment of the invention provides a method for determining a direct current time constant of a short circuit fault current at the outlet end of a generator, belonging to the technical field ofshort circuit fault at the outlet end of the generator of a thermal power station. The method for determining the direct current time constant of the short circuit fault current at the outlet end of the generator comprises the following steps: collecting short circuit current waveform data; performing normalization processing on the collected short circuit current waveform data to obtain processedcurrent data; determining a time corresponding to an extreme point of the current data in a predetermined time interval to calculate a short circuit closing angle [Phi]; integrating the current datain a time domain to obtain an integrated waveform data; calculating a first time T<1> and a second time T<2>; calculating a first time constant Ta<1> and a second time constant Ta<2>; calculating a relative deviation x of the direct current time constant; and judging whether the relative deviation x is less than or equal to a deviation threshold [Delta], and the time constant calculation result isthe direct current time constant when it is judged that the relative deviation x is less than or equal to the threshold [Delta].

Description

technical field [0001] The invention relates to the technical field of short-circuit fault at the outlet end of a thermal power station generator, in particular to a method for determining the DC time constant of an asymmetric short-circuit fault current at the outlet end of a generator. Background technique [0002] When a thermal power station generator has an asymmetric short-circuit fault at the outlet, since the generator is a hidden pole type, the short-circuit current has the following expression: [0003] [0004] It can be seen from the above formula that the AC component of the asymmetric short-circuit fault current at the outlet of the generator has attenuation characteristics ( figure 1 Among them, I0 is the asymmetrical short-circuit current, I1 is the DC component, and I2 is the AC component). Therefore, using the envelope method given in "GB1984 High Voltage AC Circuit Breaker" to calculate the DC component at any time to calculate the DC time constant can...

AI Technical Summary

Problems solved by technology

Therefore, using the envelope method given in "GB1984 High Voltage AC Circuit Breaker" to calculate the DC component at any time to calculate the DC time constant cannot solve such problems

Therefore, it is impossible to accurately evaluate and calculate the DC time constant of the thermal power station from the asymmetric short-circuit fault current waveform at the generator outlet of the power station, nor can it provide accurate technical parameters for the generator circuit breaker to break the asymmetric short-circuit fault at the generator outlet of the power station

Images