Large-scale hydro-generator rotor de-excitation and overvoltage protection combined device

Abstract

Provided is a large-scale hydro-generator rotor de-excitation and overvoltage protection combined device. The large-scale hydro-generator rotor de-excitation and overvoltage protection combined device comprises an excitation system silicon controlled rectifier bridge, a dual-fracture DC circuit breaker with a normally-closed contact, and a forward and backward rotor overvoltage protection device formed by an overvoltage trigger and a zinc oxide nonlinear resistor. A current relay with a time-delay function is connected in series in an overvoltage protection loop. A de-excitation device is formed by a silicon carbide nonlinear resistor which is connected in parallel between the positive and negative electrodes of a power generator rotor. The silicon carbide nonlinear resistor is connected with an auxiliary switch. De-excitation can be rapidly and reliably performed, and automatic disconnection of the loop after overvoltage disappearance can also be guaranteed.

Description

technical field [0001] The invention belongs to the field of water conservancy and hydropower facilities, and in particular relates to a combined device for demagnetization and overvoltage protection of a large generator. Background technique [0002] In recent years, my country's hydropower construction has developed by leaps and bounds. With the increase of unit capacity, the excitation voltage and current of generators have also risen to a new level. This brings severe challenges to the scheme design and equipment selection of the demagnetization system of the unit. The important function of the de-excitation device is to quickly cut off the excitation of the generator when accidents such as short circuit and grounding occur inside and outside the generator, and quickly consume the magnetic field energy stored in the excitation winding of the generator in the energy-consuming components of the de-excitation device. Avoiding or reducing damage to equipment and limiting the...

AI Technical Summary

Problems solved by technology

However, the silicon carbide resistor has a large leakage current and cannot be directly connected in parallel at both ends of the generator. A jumper or auxiliary fracture must be used to isolate it. When used as an overvoltage protection resistor, it cannot be automatically shut down after the positive overvoltage disappears. Can use the inverter demagnetization method to cause the shutdown of the unit

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