Method for extracting resistive current of metal oxide arrester (MOA)

A technology of resistive current and extraction method, which is applied in the direction of measuring current/voltage, instrument, measuring electricity, etc., and can solve problems such as method error

Inactive Publication Date: 2011-03-16
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Abstract
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Problems solved by technology

The harmonic analysis method decomposes the voltage and current signals into harmonics by FFT, and considers that the harmonics of the voltage and the harmonics corresponding to the resistive current are in the same phase. This characteristic is true for linear resistors, but for non Linear resistance does not have the above relationship, so the method also has errors

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  • Method for extracting resistive current of metal oxide arrester (MOA)
  • Method for extracting resistive current of metal oxide arrester (MOA)
  • Method for extracting resistive current of metal oxide arrester (MOA)

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Embodiment Construction

[0018] When the leakage current flowing through the MOA is less than 1mA, the MOA is in the small current region, and the MOA equivalent circuit model in the small current region is as attached figure 1 shown.

[0019] attached figure 1 R is the non-linear resistance of MOA; C is the dielectric capacitance; i R is the resistive current; i C Is the capacitive current; i is the full current; u is the voltage applied to the arrester.

[0020] Voltage u, full current i, resistive current i R and capacitive current i C Satisfy the following relationship:

[0021] i R = f(u) (1)

[0022] i C = C du dt - - - ( 2 )

[0023] i=i C + i R (3)

[0024] where i R =f(u) is the voltage-current relationship of the non-linear resistor, which is an algebraic relationship.

[0025] Let T be the period of the volta...

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Abstract

The invention provides a method for extracting the resistive current of a metal oxide arrester (MOA). The technical scheme comprises the following steps of: acquiring a voltage signal applied to the arrester and leakage current flowing through the MOA and performing fast Fourier transform on the voltage signal to acquire the amplitude and phase of each subharmonic; acquiring a capacitive current signal of which the waveform is the same as that of capacitive current of the arrester and the amplitude is in proportion to that of the capacitive current of the arrester according to a phase relationship between a voltage signal and a current signal on a capacitor and the acquired amplitude and phase of each subharmonic of voltage; and acquiring the resistive current of the arrester according to the principle that the resistive current is orthogonal to the capacitive current of the arrester. The method has a rigorous principle and is convenient to implement; a digital signal has high anti-jamming capability; phase shift is processed by the fast Fourier transform, so even if each subharmonic exists theoretically, errors cannot be generated; and the measurement accuracy of the resistive current can be effectively improved in practical application.

Description

technical field [0001] The invention belongs to the field of electrical equipment testing, and in particular relates to a method for extracting resistive current from a metal oxide arrester. Background technique [0002] Metal Oxide Arrester (MOA) is an important overvoltage protection device in power system because of its small size, low cost, superior protection performance, good nonlinear characteristics, large flow rate, and low residual voltage. At present, MOA is not only used in almost all high-voltage and ultra-high-voltage power systems, but also used in a large number of power systems that have been put into operation. With the wide application of MOA in the power system, the security of the power system has been greatly improved, and the cost of equipment has also been reduced, resulting in huge economic and social benefits. After decades of on-site operation, while MOA has fully demonstrated its advantages, it has also exposed its shortcomings and deficiencies. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/00G01R19/00
Inventor 律方成徐志钮李燕青王永强谢红玲
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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