Phase modifier frequency conversion starting process short circuit fault protection method and device

Abstract

The invention discloses a phase modifier frequency conversion starting process short circuit fault protection method and device. The method comprises the following steps of acquiring a phase modifiermachine end side voltage, a phase modifier neutral point side current, a computer end side voltage amplitude and frequency, and a ratio of the machine end side voltage to a frequency per unit value, and calculating a neutral point side current amplitude and a neutral point side current amplitude variation; in an initial constant magnetic flux starting stage, when the ratio of the phase modifier machine end side voltage to the frequency per unit value is reduced to exceed a setting value and a neutral point side current amplitude is increased to exceed the setting value, determining to be a short-circuit fault; or in a constant-voltage starting stage, when the machine end side voltage is reduced to exceed the setting value and the neutral point side current amplitude is increased to exceedthe setting value, determining to be the short-circuit fault; and after the short-circuit fault is judged, carrying out short-time delay protection on alarming or tripping. In the technical scheme, short-circuit fault protection criteria in the frequency conversion starting process are proposed in a segmented mode, and sensitivity of short-circuit fault protection in the phase modifier frequency conversion starting process can be improved.

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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