Device and method for protection of electric reactors in series connection

Abstract

The invention discloses a device and method for protection of electric reactors in series connection. The method is realized based on a protection device, the reactors in series connection and the capacity ratio of capacitors are determined according to harmonic order which is required to be inhibited; normal impedance ratio and impedance ratio error are further obtained; actual impedance ratio is calculated through collecting busbar voltage value, shunt capacitance voltage value, and loop current value; whether the actual impedance ratio exceeds the set impedance ratio error or not is determined; if the absolute value of the difference between the actual impedance ratio and the normal impedance ratio exceeds the set impedance ratio error, an alarm is sent, and the reactors in series connection is drawn back from the system. The device and the method overcome the problem of safety in operation of reactors in series connection in a conventional shunt capacitance compensation device, solve the short circuit problem of a winding wire compartment in the reactors in series connection, and solve the problems of turn-to-turn short circuit and layer short circuit of the reactors in series connection, so as to guarantee the safety in operation of the reactors in series connection.

Description

technical field [0001] The invention relates to the field of reactive power compensation of shunt capacitors in electric power systems, in particular to a protection device and a protection method applied in the reactive power compensation system of shunt capacitors. Background technique [0002] The reactors used in the power system are mostly divided into series reactors and shunt reactors. Among them, series reactors are mostly used in series or parallel connection with capacitors in the filter circuit to limit the higher harmonics in the power grid, so as to achieve the purpose of protecting capacitors. Series reactors, like capacitors, are very sensitive to overvoltage, overcurrent and high-order harmonics. If series reactors are used improperly, they are prone to damage or even burn out. Therefore, the shunt capacitance compensation device of the power system basically adopts series reactor The wiring type of the setting, and the relay protection device is used to pro...

AI Technical Summary

Problems solved by technology

[0003] However, during the operation of the system, when the series reactor has inter-turn short circuit, interlayer short circuit, winding wire package short circuit, and series reactor and capacitor connection soft wire short circuit to ground, the series reactor is completely or partially bypassed. Keeping the voltage unchanged, the total reactance value of the filter branch increases, the short-circuit current decreases, the short-circuit current is less than the normal working current of the filter, and the terminal voltage of the capacitor decreases, so in the relay protection device, the quick-break that reflects the current increment And the overcurrent protection will not operate, the voltage protection based on the bus voltage will not operate, and the capacitor body differential pressure protection will not operate, so that the current relay protection cannot identify this kind of fault and form a dead zone for operation protection

What's more serious is that due to the close distance between the capacitor and the series reactor, the series reactor burns out and catches fire. If the capacitor bank is endangered and the capacitor explodes, it will lead to a serious power supply liability accident.

Images