Method and device for short-circuit fault protection during frequency conversion start-up of a condenser

Abstract

The invention discloses a short-circuit fault protection method and device in the frequency conversion start-up process of a condenser. The ratio of voltage to frequency per unit value, calculate the current amplitude on the neutral point side, and the change in the current amplitude on the neutral point side; in the initial constant magnetic flux start-up stage, compare the reduction in the ratio of the voltage to the frequency per unit value at the side of the condenser If it exceeds the set value, and the current amplitude on the neutral point side increases beyond the set value, it is judged as a short-circuit fault; When the value is set, it is judged as a short-circuit fault; after it is judged as a short-circuit fault, the short-time delay protection action will alarm or trip. This technical scheme puts forward the short-circuit fault protection criterion in the frequency conversion starting process in sections, which can improve the sensitivity of the short-circuit fault protection in the frequency conversion starting process of the condenser.

Description

technical field [0001] The invention belongs to the field of relay protection, in particular to a short-circuit fault protection method and a device using the method in the frequency conversion start-up process of a condenser. Background technique [0002] The synchronous condenser has a large reactive power compensation capacity. When the grid voltage drops, the excitation system of the condenser can automatically adjust and implement forced excitation, and continuously provide reactive power to the system, especially for improving the UHV AC-DC hybrid grid. Voltage stability and dynamic reactive power support capability are of great significance. [0003] Since there is no prime mover for a large synchronous condenser, it is generally started by a static frequency converter, gradually dragged from zero Hz to the rated frequency, and then checked for synchronization and connected to the grid. Therefore, unlike conventional generators, the stator and rotor windings of the c...

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Problems solved by technology

Therefore, unlike conventional generators, the stator and rotor windings of the condenser are always charged during the start-up phase, and the frequency is the frequency conversion process from zero Hz to rated frequency. The sensitivity of the conventional protection function based on the rated frequency decreases, and there must be a sensitive short circuit during the frequency conversion start process. failsafe

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