Three-phase power supply network electromagnetic voltage transformer harmonic elimination protector

Abstract

The invention relates to a voltage transformer harmonic elimination protector, in particular to a three-phase power supply network electromagnetic voltage transformer harmonic elimination protector, which comprises a capacitor. The capacitor is connected in parallel with a resettable fuse to form the harmonic elimination protector; and the harmonic elimination protector is connected in series between a neutral point and a ground point of a primary side of a three-phase electromagnetic voltage transformer to prevent ferromagnetic resonance overvoltage. The three-phase power supply network electromagnetic voltage transformer harmonic elimination protector can effectively eliminate ferromagnetic resonance caused by using the electromagnetic voltage transformer in a power supply system so as to prevent the generated overvoltage from damaging multiple kinds of equipment in the system, cannot influence normal operation of other protectors in the power supply system, has the advantages of simple structure, convenient use and low manufacturing cost and use cost, and can be widely applied to the power supply system of the 3 to 35kV three-phase power supply network electromagnetic voltage transformer.

Description

【Technical field】 [0001] The invention relates to a voltage transformer harmonic elimination protector, in particular to a three-phase power grid electromagnetic voltage transformer harmonic elimination protector. 【Background technique】 [0002] At present in our country, based on economic reasons, the 3-35kV system in the three-phase power grid adopts the three-wire system with the neutral point not grounded. In order to monitor the insulation status of the system, three-phase voltage transformers are connected to the power plant, substation, and generator bus. When connecting, the primary side (high voltage) winding of the three-phase voltage transformer is connected in a star shape, and the neutral point of the star shape is directly grounded. For cost considerations, three-phase voltage transformers basically use electromagnetic voltage transformers. This kind of power system using three-phase electromagnetic voltage transformers has some changing factors to the ground...

AI Technical Summary

Problems solved by technology

However, although this three-phase electromagnetic voltage transformer with a primary resonance eliminator can eliminate the ferromagnetic resonance problem of the system, it also has shortcomings. First, due to the existence of the resistance value, the voltage transformer primary The neutral point on the side of the voltage transformer is not directly grounded. When the system is running normally, this resistance will cause the neutral point of the voltage transformer to be unbalanced, so that the open delta winding of the voltage transformer will generate a zero-sequence voltage, thereby affecting the protection of the relay protection device in the system. Normal operation; Secondly, when a single-phase ground fault occurs in the system, the existence of the resistance will cause the neutral voltage of the voltage transformer to shift, which will reduce the zero-sequence voltage induced by the open delta winding of the voltage transformer, thereby affecting the relay protection normal operation of the device

In short, while the existing three-phase electromagnetic voltage transformer eliminates the ferromagnetic resonance of the power system, it also brings unstable factors to the system and buryes hidden dangers for the safe operation of the system.

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