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Method for detecting any-th harmonic component and reactive current of three-phase four-wire system

A technology of three-phase four-wire system and arbitrary harmonics, applied in the direction of measuring current/voltage, measuring electrical variables, measuring devices, etc., can solve problems such as large detection errors and inability to detect current reactive components

Active Publication Date: 2014-05-07
STATE GRID CORP OF CHINA +4
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Problems solved by technology

However, the p-q method has a large detection error in the case of non-sinusoidal system voltage, i p -i q The method cannot detect the reactive component in the current and is only applicable to the three-phase three-wire system

Method used

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  • Method for detecting any-th harmonic component and reactive current of three-phase four-wire system

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Embodiment Construction

[0063] The present invention will be further described below in conjunction with the accompanying drawings.

[0064] A method for detecting harmonic components of any order and reactive current in a three-phase four-wire system includes the following steps:

[0065] Step (1): If figure 1 As shown, the phase θ of the fundamental positive sequence voltage component of the grid voltage is obtained through the phase-locked loop + (ω 0 t): three-phase grid voltage u a , u b , u c After CLARK transformation and PARK transformation, the d-axis voltage component u is obtained d and the q-axis voltage component u q ; The fundamental positive sequence voltage component appears as a DC quantity on the d-axis and q-axis, while the fundamental negative-sequence voltage component and other sub-harmonic components appear as an alternating current quantity on the d-axis and q-axis; u q The AC flow is filtered out by a low-pass filter (LPF), and the q-axis DC flow is obtained The erro...

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Abstract

The invention discloses a method for detecting an any-th harmonic component and a reactive current of a three-phase four-wire system. The method is characterized by comprising the following steps that (1) phase locking is conducted, and the phase theta [+] (omega [0] t) of the positive sequence voltage of a fundamental wave is obtained; (2) the positive sequence component of the n-th harmonic is detected; (3) the negative sequence component of the n-th harmonic is detected; (4) the zero-sequence component of the n-th harmonic is detected; (5) the reactive current is detected. The method for detecting the any-th harmonic component and the reactive current of the three-phase four-wire system is based on transformation of the coordinates of the n-th harmonic and the LPF technology, and the particularity of the zero-sequence current detection is considered. According to the method for detecting the any-th harmonic component and the reactive current of the three-phase four-wire system, the loop-locked phase locking method is adopted, the accuracy of phase locking is guaranteed, and therefore a reliable phase is provided for transformation of the coordinates; the physical conception is clear, the implementation mode is simple, the application range is wide, the detection accuracy is high, and the practicability is high.

Description

technical field [0001] The invention relates to a method for detecting arbitrary harmonics and reactive currents of a three-phase four-wire system, which can detect arbitrary harmonics in the three-phase four-wire system under the condition of asymmetrical and non-sinusoidal three-phase voltages The positive sequence, negative sequence, zero sequence components and reactive current, this method is also applicable to the detection of three-phase three-wire system, which belongs to the application field of electric power technology. Background technique [0002] Due to the large number of applications of nonlinear loads and induction motors, industrial users generally have problems such as serious harmonic pollution and low power factor. Three-phase four-wire active filter (APF) can be used for harmonic control and reactive power compensation, and the accuracy of harmonic and reactive current detection is the premise and key for APF to perform harmonic and reactive power accur...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R23/165G01R19/00
Inventor 梁营玉刘建政许杏桃王一杨奇逊
Owner STATE GRID CORP OF CHINA
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