An Electronic Synchronization Check Relay

Abstract

The invention relates to an electronic synchronous inspection relay of a hydroelectric generator set, which includes an isolation transformer TV1, an isolation transformer TV2, a rectifier bridge, a comparator LM393, a voltage reference circuit, an inverter ULN2003 and a synchronous relay TJ, from the generator The secondary voltage signal of the power grid is connected to the isolation transformer TV1 and the isolation transformer TV2 respectively, and the two identically-named terminals UNIT I‑ and GRID I‑ of the secondary side outputs of the isolation transformer TV1 and TV2 are connected, and the secondary side output terminal UNIT I+ and GRID I+ are connected to the input terminal of the rectifier bridge, and the output filter circuit of the rectifier bridge is composed of C20~C22. The inspection relay of the present invention can accurately compare the voltage and frequency of the generator and the power grid, so that the grid connection is fast and stable.

Description

technical field [0001] The invention relates to a frequency-measuring and grid-connected synchronous inspection relay for a hydroelectric generating set. Background technique [0002] During the start-up and grid-connection process of the hydro-generator set, it is necessary to measure the voltage frequency of the generator set in real time, and track the frequency of the grid, so as to realize the synchronization and paralleling of the generator set and the grid. The synchronous check relay analyzes and compares the voltage signals of the unit and the power grid to output a more accurate grid-connected closing signal. The current conventional synchronization checker simply connects the machine frequency signal and network frequency signal circuit in series for voltage phase comparison, and directly connects the compared voltage difference to the coil of the electromagnetic relay, and the output contact of the relay controls the closing signal of the circuit breaker . Howe...

AI Technical Summary

Problems solved by technology

However, due to the influence of the high-order harmonics of the generator itself, the waveform is distorted. The voltage input signal of the electromagnetic relay often cannot reflect the voltage phase difference and voltage difference between the real generator and the grid, and it is easy to cause the synchronous relay to malfunction and issue a wrong closing switch. Signal

In addition, when the voltage difference between the generator and the power grid is at the critical point of the synchronous relay action, the output contact of the relay is also quite unstable, switching back and forth between on and off frequently, which may easily lead to closing malfunctions. Generator sets and grid shocks

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