Harmonic error measurement correction device for capacitive voltage transformer

Abstract

The invention provides a harmonic error measurement correction device for a capacitive voltage transformer. The device comprises a harmonic generation module, a high voltage generation module, an accurate value output module, a measured CVT output module, a data processing module, and a result output module. An output value of a capacitive voltage divider and an output value of a test capacitor voltage transformer are compared, so as to obtain an actual transfer coefficient of the capacitive voltage transformer under a certain harmonic frequency, transfer coefficients of the capacitive voltagetransformer under 2-50 harmonic frequencies can be deduced through a neural network model according to transformation ratio coefficients under a plurality of frequencies, and a correction coefficientof 2-50 harmonic is output according to the transfer coefficient of each harmonic.

Description

technical field [0001] The invention belongs to the technical field of voltage measurement, in particular to a device for measuring and correcting harmonic errors of capacitive voltage transformers. Background technique [0002] In 110kV, 220kV and higher voltage grids, the main voltage transformer used is the Capacitor Voltage Transformer (CVT). my country's CVT has very mature experience in design and manufacturing level and product quality, and its operation reliability has been significantly improved. It is widely used in high-voltage and ultra-high-voltage systems. According to some data, since 1995, the production and sales of CVT have grown at an average annual rate of 25%. CVT is used in a small number of 35kV substations. At 110-220kV, CVT has outstanding advantages, so it is generally used in new substations. Some substations that need to be renovated often use CVT instead of PT, and almost all 330-500kV use CVT. . When using a CVT to measure voltage, since the ...

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Problems solved by technology

According to the standard, when using CVT for voltage measurement, the accuracy of fundamental voltage can be guaranteed, but the frequency range of CVT is limited, and distortion and deviation will appear in the measurement results of harmonic voltage, so it cannot be used for harmonic measurement

GB / T 15459 Power Quality Public Grid Harmonics (Draft for Comments) also stipulates that CVT cannot be used for harmonic voltage measurement, but it does not specify the test instruments and methods that should be selected

[0003] However, in the 110kV and above voltage level grid application CVT site, the harmonic measurement results basically come from the CVT, and the transmission of the harmonics by the CVT has actually undergone nonlinear changes

The CVT secondary side harmonic voltage can no longer truly reflect the high voltage side harmonics. Although the accuracy of the low voltage side harmonic measurement equipment can meet the requirements, it can only restore the high voltage side harmonic level after CVT distortion.

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