Hydroelectric generating set frequency measurement method and system

Abstract

The invention relates to a hydroelectric generating set frequency measurement method and system. The method comprises the steps of sampling a line voltage signal of a hydroelectric generating set, carrying out the preprocessing of the line voltage signal, and synchronously transmitting the line voltage signal to an A channel and a B channel, wherein the channel A is used for processing a residualvoltage state signal, and the B channel is used for processing a rated state signal; and judging whether the hydroelectric generating set is in grid-connected operation, and selecting the output valueof the channel A or the channel B to calculate the hydroelectric generating set frequency according to the judgment result. According to the invention, double-channel frequency measurement is adopted; residual voltage state signals can be collected, and rated state signals can also be collected; the redundancy and the measurement accuracy of the system are improved; and by using the method provided by the invention, the measurement accuracy of the machine frequency signal is improved, and the probability of non-accident shutdown of the unit and other related misoperation caused by interference of the machine frequency signal is reduced.

Description

technical field [0001] The invention relates to the field of hydroelectric generator control, in particular to a method and system for measuring the frequency of a hydroelectric generator. Background technique [0002] The frequency of the hydroelectric generating set (abbreviated as machine frequency) is an extremely important input signal of its control system. The start-up and shutdown of the unit, especially the safety, are directly related to the machine frequency signal. Therefore, the reliability of the machine frequency signal acquisition determines the Performance of the unit control system. Independent devices such as governors and speed relays in the hydroelectric unit control system need to sample and measure the machine frequency. The residual voltage of the machine frequency signal at the beginning of the unit’s startup or at the end of the shutdown shows low-voltage and low-frequency characteristics. In order to collect weak For the residual voltage signal, t...

AI Technical Summary

Problems solved by technology

Although such a processing method can meet the measurement requirements of the machine frequency signal from the residual voltage state to the rated state, but because of the large amplification factor, it is easy to amplify the interference signal to a non-negligible amplitude at the same time, which seriously affects the machine frequency measurement. , the control system will collect a frequency other than 50Hz when the unit has been connected to the grid, resulting in a malfunction and emergency shutdown when it should not be stopped, affecting the power generation efficiency and assessment indicators of the power station

There are also designs that use dual-channel or multi-channel redundant frequency measurement, but it involves double voting or multiple voting methods. How to correctly select two or more frequency values ​​is not easy to implement and difficult to adapt to various situations.

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