Electronic type synchronous check relay

Abstract

The invention relates to an electronic type synchronous check relay of a hydroelectric generating unit. The relay includes an isolation transformer TV1, an isolation transformer TV2, a rectifier bridge, a comparator LM393, a voltage reference circuit, a phase inverter ULN2003 and a synchronous relay TJ; secondary voltage signals from a generator and a power grid are respectively connected with the isolation transformer TV1 and the isolation transformer TV2; two homonym ends UNIT I-and GRID I- of the secondary side output of the isolation transformer TV1 and the isolation transformer TV2 are connected with each other; secondary side output ends UNIT I+ and GRID I+ of the isolation transformer TV1 and the isolation transformer TV2 are connected into the input end of the bridge rectifier; and the output filtering circuit of the bridge rectifier is composed of C20 to C22. With the check relay of the invention adopted, the voltages and frequencies of the generator and the power grid can be compared accurately, and grid connection can be performed fast and stably.

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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