Voltage sag detection method combining three-phase voltage break variable and zero-sequence voltage

A technology of voltage mutation and zero-sequence voltage, applied in the direction of fault location, etc., can solve the problems that are difficult to achieve fast and accurate identification of fault types, processing large amounts of data, and large amount of calculations

Active Publication Date: 2015-09-16
STATE GRID CORP OF CHINA +2
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Problems solved by technology

[0004] However, the existing voltage sag detection method has the disadvantages of large amount of calculation and processing data, which makes it difficult to quickly and accurately identify the fault type

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  • Voltage sag detection method combining three-phase voltage break variable and zero-sequence voltage
  • Voltage sag detection method combining three-phase voltage break variable and zero-sequence voltage
  • Voltage sag detection method combining three-phase voltage break variable and zero-sequence voltage

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Embodiment Construction

[0027] see Figure 1 to Figure 3 As shown, a voltage sag detection method combining three-phase voltage mutation and zero-sequence voltage in the present invention comprises the following steps:

[0028] (1) Three-phase voltage acquisition and calculation of characteristic quantities

[0029] figure 1 The voltage on the secondary side of the voltage transformer on the bus side of the distribution network in the distribution network is processed by low-pass filtering and sample-and-hold to obtain the instantaneous value u of the three-phase voltage during the voltage sag of the line a (k), u b (k), u c (k), combined with the instantaneous value u of the power frequency cycle before the sag a (k-N), u b (k-N), u c (k-N) Calculation of sudden change Δu of three-phase voltage instantaneous value φ (k) (φ=A, B, C) and zero-sequence voltage instantaneous value u 0 (k), where:

[0030] Δu φ (k)=u φ (k)-u φ (k-N)=u φ (k 0 +m)-u φ (k 0 +m-N), m≤N / 2

[0031] u 0 (k)=u ...

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Abstract

The invention relates to the electric energy quality monitoring field, and discloses a voltage sag detection method combining three-phase voltage break variables and zero-sequence voltage. The voltage sag detection method comprises the steps of: firstly, acquiring three-phase voltage instantaneous values ua (k), ub (k) and uc (k) of a circuit during the voltage sag period, and calculating corresponding three-phase voltage break variables delta u phi (k) (phi = A, B, C) and a zero-sequence voltage instantaneous value u0 (k); secondly, achieving the distinction of grounding faults and non-grounding faults by utilizing the conditions that the zero-sequence voltage U0 is greater than or equal to U0th which equals to k0*UN, wherein k0 is selected from 1% to 2%; thirdly, confirming fault phases by utilizing characteristics of a phase voltage break variable shown in the description; and finally calculating voltage sag depth by utilizing an equation shown in the description. The voltage sag detection method provides a basis for fast and accurate voltage sag compensation according to phases.

Description

【Technical field】 [0001] The invention relates to the field of electric energy quality detection research, in particular to a voltage sag detection method. 【Background technique】 [0002] Voltage sag is one of the most serious power quality problems in power systems, which seriously threatens the performance of voltage-sensitive equipment such as frequency converters. Among them, the short-circuit fault is the main factor causing the voltage sag. Accurate and fast judgment of the fault type is conducive to the targeted implementation of voltage sag compensation, so as to ensure the voltage quality of voltage-sensitive users. [0003] Existing research on voltage sag detection mainly focuses on voltage sag amplitude and jump phase, and mainly uses the symmetrical component method to construct corresponding criteria to identify fault types, and to study the relationship between fault types and voltage sags less. There are two main types of symmetrical component method and do...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08
Inventor 王建波邵文权锁军张艳丽尹俊钢周倩
Owner STATE GRID CORP OF CHINA
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