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Method for detecting voltage drop of three-phase power network based on mean-value filter

A technology of grid voltage and voltage sag, applied in the direction of measuring current/voltage, measuring device, measuring electrical variables, etc., to achieve the effect of small calculation amount and high reliability

Inactive Publication Date: 2011-08-17
SAMIL POWER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

If judged according to the voltage effective value in the prior art, it can only be detected within 10ms (1 / 2 mains cycle) at the fastest

Method used

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  • Method for detecting voltage drop of three-phase power network based on mean-value filter
  • Method for detecting voltage drop of three-phase power network based on mean-value filter
  • Method for detecting voltage drop of three-phase power network based on mean-value filter

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Embodiment 1

[0012] Such as figure 2 As shown, when the power grid is in a three-phase short circuit, the d-axis voltage is a stable DC flow. When the power grid is in a single-phase short circuit and phase-to-phase short circuit, the power grid voltage is asymmetrical, and there will be a second harmonic component on the d-axis component of the voltage.

[0013] S101. Use an average value filter to perform average value filtering on the d-axis component of the voltage to obtain an average value of the d-axis voltage.

[0014] Use 1 / 4 mains cycle (5ms) average value filter to carry out average value filtering on the d-axis component of the voltage to obtain the average value of the d-axis voltage, which can filter out the second harmonic component.

[0015] S102. Determine whether the grid voltage drops according to the average value of the d-axis voltage.

[0016] Specifically:

[0017] S1021. Sampling the switching frequency of the inverter and the number of points at which the mains ...

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Abstract

The invention provides a method for detecting voltage drop of a three-phase power network based on a mean-value filter, comprising the steps of utilizing the mean-value filter to carry out mean-value filtering on d-axis component of the voltage and obtaining the mean value of the d-axis voltage; and judging the drop situation of the voltage in the power network according to the mean value of the d-axis voltage. According to the method, the metering quantity is small and the reliability is high, and a negative-sequence current component can be inhibited when the voltage of power network is unbalanced. The invention provides the method for quickly detecting the voltage drop, can be used for detecting the drop situation of the voltage within the 1 / 4 commercial electricity period, and is easy to be applied in practical situation, and the metering quantity is small and the reliability is high,.

Description

technical field [0001] The invention particularly relates to a three-phase grid voltage drop detection method based on average value filtering. Background technique [0002] At present, with the gradual development of new energy grid-connected power generation such as wind power and photovoltaics, MW-level grid-connected inverters are widely used. In order to ensure the stability of the power grid, the demand for low voltage ride through (LVRT) is put forward for the grid-connected inverter. In the low-voltage ride-through standard, the inverter is required not to disconnect from the grid after the grid voltage drops, and can inject reactive current into the grid within 20ms to raise the grid voltage. This puts forward requirements on the detection time of the three-phase grid voltage drop. The power grid drop is caused by the short circuit of the power grid. There are three types of short circuit, namely single-phase short circuit, phase-to-phase short circuit, and three-...

Claims

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Application Information

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IPC IPC(8): G01R19/165
Inventor 周谦陈晓高
Owner SAMIL POWER
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