Analytical model method for current conversion ratio and phase difference of open-type current transformer

A technology of current transformers and analytical models, applied to the phase angle between voltage and current, measuring electrical variables, instruments, etc., can solve problems such as incompatibility, waste, and measurement errors

Active Publication Date: 2014-12-17
STATE GRID CORP OF CHINA +1
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Problems solved by technology

This is because the change of the air gap will obviously change the impedance of the magnetic circuit, so that the accuracy of the current transformer will also change, resulting in measurement errors
Therefore, in the actual power grid, the current transformer for measurement and the current transformer for protection are two independent devices, which are not compatible with each other.
Obviously, such a design increases the volume and functional redundancy of the current transformer, resulting in a large waste

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  • Analytical model method for current conversion ratio and phase difference of open-type current transformer
  • Analytical model method for current conversion ratio and phase difference of open-type current transformer
  • Analytical model method for current conversion ratio and phase difference of open-type current transformer

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[0065] In order to further quantify and more intuitively display the analytical model of the open-type current transformer established in this patent application, the main working characteristics of the open-type current transformer considering the secondary load are discussed in conjunction with a specific embodiment. The relative difference between the actual current ratio of the open-type current transformer and the ideal current transformer current ratio is defined as:

[0066] ϵ = 1 αN - 1 = [ 1 + L N ...

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Abstract

The invention relates to an analytical model method for the current conversion ratio and the phase difference of an open-type current transformer. The analytical model method comprises the following steps of: (1) establishing the principle model of the open-type current transformer; (2) deriving the magnetic path time-domain equation of the open-type current transformer according to an ohm law for magnetic path, calculating a circuit time-domain equation considering a secondary side load according to a Faraday law of electromagnetic induction and the ohm law, obtaining the actual current conversion ratio and phase difference calculation formulas of the primary side and the secondary side of the open-type current transformer by the magnetic path and circuit time-domain equations, so as to complete an analytical model for the current conversion ratio and the phase difference of the open-type current transformer. The analytical model established by the method disclosed by the invention has an important theoretical direction value on realization for compatibility between the current transformer for measurement and a current transformer for protection, and is capable of providing a theoretical basis for the error compensation of a split core type current transformer used for online calibration for an electric energy meter.

Description

technical field [0001] The invention belongs to the technical field of electromagnetic measurement, in particular to an analytical model method for the current transformation ratio and phase difference of an open-type current transformer. Background technique [0002] Current transformers are widely used in power plants, substations and distribution networks. They are one of the key equipment for power system energy metering, status detection, fault diagnosis and protection, and are also the basis for real-time information management of power supply and consumption under smart grids. One of the sensor devices. Traditional current transformers generally adopt a closed magnetic circuit design, that is, the core of the current transformer is designed as a closed magnetic ring, and the primary winding and the secondary winding are wound on the closed circular core. [0003] The closed magnetic circuit design can ensure that the magnetic circuit has a small magnetic impedance, s...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R25/00G01R35/02G01R29/20
Inventor 陈彬卢欣刘洋洋
Owner STATE GRID CORP OF CHINA
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