Capacitive electromagnetic potential transformer used in power system

Abstract

The invention provides a capacitive electromagnetic voltage transformer which is applied to a power system and characterized in that the primary side winding turns are arranged so as to lead the grounding equivalent capacitance 1 / Omega C of the primary side winding of the voltage transformer is less than the primary side winding inductance Omega L; the primary side resistance of the transformer presents capacitive. By reasonably arranging the primary winding turns, the capacitive electromagnetic voltage transformer leads the voltage transformer to present capacitive; the capacitive voltage transformer and a system capacitor can not form an LC circuit, thus effectively preventing the generation of ferromagnetic resonance of the voltage transformer; meanwhile, advantages of the electromagnetic voltage transformer such as simple structure, good transient response characteristic and being not affected by environmental temperature are sufficiently exerted.

Description

technical field [0001] The invention relates to the application of voltage transformers for power transmission and distribution, power plants and substations in power systems. Background technique [0002] Electromagnetic voltage transformers are widely used in power systems. Ferromagnetic resonance occurs in systems above 110kV, so CVT capacitor voltage transformers are used in 110kV systems. Corresponding to each phase, separate independent voltage transformers are set up. One end of the primary side of each voltage transformer is connected to the phase line, and the other end is grounded. The voltage is output on the secondary side of the voltage transformer for use by instruments and related protection controls. . [0003] Under the normal working voltage of the electromagnetic voltage transformer in the prior art, the magnetic density of the iron core is usually not high, the iron core is not saturated, the equivalent capacitive reactance to the ground is greater than ...

AI Technical Summary

Problems solved by technology

After the voltage transformer resonates, the non-power frequency energy or "excited" energy generated by its own saturation makes the voltage transformer deeply saturated, so it is difficult for the voltage transformer to disappear after saturation

The current solutions mainly include: choose a voltage transformer with better excitation characteristics, add a linear resistor to the open triangle winding of the voltage transformer, install an automatic microcomputer harmonic elimination device on the open triangle of the voltage transformer, and connect the primary neutral point of the voltage transformer to zero sequence. The voltage transformer, the LXQ resonance eliminator connected between the primary neutral point of the voltage transformer and the ground, etc. have their own advantages, but also have their own disadvantages, and they cannot fully solve the problem of ferromagnetic resonance of the voltage transformer.

[0006] In order to prevent ferromagnetic resonance at voltage levels above 110kV, CVT capacitive voltage transformers are used, but the transient response characteristics are worse than electromagnetic ones, the structure is complex, the volume is large, the manufacturing price is high, the stability is poor, and the accuracy is greatly affected by temperature.

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