Neutral point controllable impedance harmonic elimination device on primary side of voltage transformer

Abstract

The invention discloses a neutral point controllable impedance harmonic elimination device on the primary side of a voltage transformer, which includes a controller and a primary harmonic elimination controllable impedance. The primary harmonic elimination controllable impedance is composed of a switch K and an impedance Z. The switch K and the impedance Z is parallel or series; one end of the primary harmonic elimination controllable impedance is connected to the primary neutral point of the voltage transformer, and the other end is grounded; Voltage judgment The resonance of the voltage transformer and the single-phase grounding of the system occur. When the voltage transformer resonates or the single-phase grounding occurs in the power grid, the controller controls the switch K to open and close alternately, and alternately changes the circuit parameters of the circuit where the voltage transformer is located. Make the resonance disappear, or prevent the voltage transformer from resonating; during normal operation, the switch K remains open and closed. The invention can realize the primary resonance elimination of the voltage transformer and ensure the safe operation of the system.

Description

technical field [0001] The invention relates to a primary harmonic elimination device for a voltage transformer and a device for automatically insulating the neutral point of the voltage transformer in a line power failure from the ground. Background technique [0002] The voltage transformer is referred to as PT, and the resonance of the voltage transformer is a common fault in the power grid. GB50064 "Code for Design of Overvoltage Protection and Insulation Coordination of AC Electrical Installations" provides a variety of measures to eliminate resonance and overvoltage in Article 6, including : [0003] 1. Select an electromagnetic voltage transformer with a higher excitation characteristic saturation point; [0004] 2. Reduce the number of neutral point grounding of voltage transformers in the same system. Except for the neutral point grounding of high-voltage windings of voltage transformers on the power supply side, the neutral points of other voltage transformers sho...

AI Technical Summary

Problems solved by technology

In recent years, there have been primary resonance eliminators using nonlinear resistors such as silicon carbide and thermistors. However, on the one hand, nonlinear resistors affect the accuracy and reliability of voltage criterion protection, and injecting nonlinear quantities into the system does not It is conducive to the safe operation of the system; on the other hand, the nonlinear resistance makes the neutral point of the voltage transformer equivalent to the ground, which makes the protection equipment that needs to protect the ground voltage unable to work normally; Accidents where mutual inductors burnt together occur frequently

[0010] In addition, after a power outage, especially after a system failure, when performing a voltage withstand test on the line before power transmission, if a DC tester is used to perform a DC withstand voltage test on the line, all PTs on the line need to be manually pulled apart. , this process is time-consuming and laborious, as long as one PT is not pulled apart, the test cannot be implemented

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