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Self-learning-based micro-grid protection method

A micro-grid and self-learning technology, applied in the comprehensive application of electronic technology, network communication technology, and relay protection technology, can solve problems such as unsuitable short-circuit faults, achieve good resolution, high sampling frequency, and improve safety sexual effect

Active Publication Date: 2016-02-10
STATE GRID CORP OF CHINA +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method can identify the short circuit between the stator turns of the generator, but it cannot be applied to the internal short circuit fault of the microgrid of the energy storage power station

Method used

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  • Self-learning-based micro-grid protection method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] The steps of the microgrid protection method based on self-learning in this embodiment are as follows (for the flow chart, see Figure 4 ):

[0042] Step 1. Real-time sampling of the full current I and system frequency f of the microgrid line. The sampling frequency range of the line current and system frequency is 2400Hz, that is, 48 ​​sampling points per cycle, and calculate the total harmonic current I ∑ and fundamental current I, total harmonic current I ∑ Including at least the second, third and fifth harmonic current components, I 2 is the second harmonic current component, I 3 is the third harmonic component of the current, I 5 is the fifth harmonic current component.

[0043] Step 2. Judging the total harmonic current I on the microgrid line within the time range of [T,T+△T] ∑ Whether there is a sudden increase, if it is determined that the total harmonic current has increased sharply, execute the judgment in step 3, otherwise return to step 1.

[0044] ...

Embodiment 2

[0051] The method of this embodiment is basically the same as that of Embodiment 1, the main difference is that in the second step, this example uses the following formula to determine whether the total harmonic current has increased sharply:

[0052] I Σ 2 I 2 ′ - I Σ 1 I 1 ′ > Δ 2

[0053] In the formula, I ∑2 is the total harmonic current at T+△T time, I′ 2 is the fundamental current at T+△T time, I ∑1 is the total harmonic current at time T, I′ 1 is the fundamental current at time T, △ 2 is the preset auxiliary criterion threshold, and its value range is 2-10.

[0054] The dynamic updating method of the auxiliary criterion th...

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Abstract

The invention relates to a self-learning-based micro-grid protection method. The method comprises the steps: a total current I and a system frequency f of a micro-grid line are sampled in real time; a total harmonic current I<sigma> is calculated; within a time range of [T, T+deltaT], when the total harmonic current I<sigma> on the micro-grid line sharply rises and a system frequency change, namely an absolute value of f<2>-f<1>, of the micro-grid exceeds a preset deviation setting valve f<d>, the condition that the micro-grid line is in a short circuit at the moment of T+deltaT is judged; a micro-grid protection is started, wherein T is an arbitrary sampling moment; deltaT is not lower than 1 / F; F is the sampling frequency; f<1> is the system frequency at the moment T; f<2> is the system frequency at the moment T+deltaT; the value range of the f<d> is 2Hz to 3Hz; and an auxiliary criterion threshold for judging whether the total harmonic current I<sigma> sharply rises or not within the time range of [T, T+deltaT] is obtained through a self-cleaning method. According to the self-learning-based micro-grid protection method, the sharp rise quantity of a harmonic component in the short circuit current is adopted as a first criterion; a frequency deviation value is adopted as a second criterion; and dynamic updating is carried out on the threshold in the first criterion, so that a relay protection of the micro-grid can be accurately achieved.

Description

technical field [0001] The invention relates to a new energy micro-grid relay protection method, which belongs to the technical field of comprehensive application of relay protection technology, network communication technology and electronic technology. Background technique [0002] For microgrids that operate flexibly and off-grid in a plug-and-play manner, the existing relay protection equipment can no longer adapt, and new principles and new methods of relay protection must be studied. The relay protection device of the microgrid needs to adapt to the two operation modes of parallel and off-grid, and the two modes should meet the requirements of rapidity, reliability, sensitivity and selectivity. [0003] During grid-connected operation, when the energy storage power station is short-circuited internally, the characteristics of the fault current are the same as those of the large power grid; while the energy storage power station is powered by power electronic equipment,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/22H02H3/52G01R23/02
Inventor 渠展展曹智慧赵玲杨宇王翼
Owner STATE GRID CORP OF CHINA