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A Method of Quickly Detecting Three-phase Voltage Sag

A three-phase voltage, fast technology, applied in the detection of negative sequence and zero sequence voltage, positive sequence field, can solve the problem of slow extraction of negative sequence components

Active Publication Date: 2021-09-14
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Abstract
  • Description
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Problems solved by technology

[0004] The invention solves the problem of slow extraction of positive sequence components and negative sequence components when a three-phase unbalanced voltage sag fault occurs

Method used

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  • A Method of Quickly Detecting Three-phase Voltage Sag
  • A Method of Quickly Detecting Three-phase Voltage Sag
  • A Method of Quickly Detecting Three-phase Voltage Sag

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Embodiment Construction

[0054] The content of the invention is a fast detection method for three-phase voltage sag, which includes three parts: extraction of positive sequence component amplitude and phase, negative sequence component amplitude and phase extraction, and zero sequence component amplitude and phase extraction. Below in conjunction with a specific example, the present invention is described in more detail, the three-phase grid voltage frequency f=50Hz is set, that is, the rotational angular velocity ω=2πf; the system sampling average rate is 20Khz, that is, the sampling interval T s = 0.005ms. Note: Considering the actual situation, the following implementation will be expressed in a discrete form, with k representing the current sampling point, and since the above three parts are performed synchronously, the three parts will be discussed separately.

[0055] The specific steps for the magnitude and phase of the positive sequence component are discussed as follows:

[0056] Step 1: Rea...

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Abstract

The invention belongs to the field of power system power quality state monitoring. At present, the relatively mature and commonly used dq transformation detection method is only suitable for three-phase symmetrical sags, and the detection time of the commonly used two-vector based control algorithm for the detection of three-phase asymmetrical voltage sags is relatively slow. Therefore, a new method is proposed. A fast detection method for three-phase unbalanced voltage sags. The invention includes three parts: using three continuous sampling points to quickly extract the amplitude and phase of the positive sequence component and negative sequence component and using a direct derivative algorithm to extract the amplitude and phase of the zero sequence component. The method can quickly detect the amplitude and phase of the positive sequence, negative sequence and zero sequence components in the three-phase unbalanced voltage, which satisfies the rapidity requirement of the dynamic voltage restorer.

Description

technical field [0001] The invention belongs to the field of power system power quality state monitoring, and relates to a detection method for positive sequence, negative sequence and zero sequence voltages in the detection of three-phase unbalanced voltage sags in grid voltages. Background technique [0002] Voltage sag is a power quality problem that has always existed in power systems. With the continuous development and progress of power equipment, equipment is becoming more and more sensitive to voltage sag, and the impact of voltage sag on power equipment is becoming more and more serious. One of the most important power quality problems affecting users. Therefore, rapid detection of grid voltage is one of the key technologies to ensure that the voltage of sensitive loads is still within an acceptable range when disturbed by system voltage. [0003] The existing research work shows that most of the detection of voltage sags is on single-phase fault events. The common...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R19/04G01R25/00
CPCG01R19/04G01R25/00
Inventor 郝晓红彭诚王子琦
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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