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Fault detection method for circuit sent out from wind power plant

A technology for fault detection and sending out lines, applied in emergency protection circuit devices, electrical components, etc., to solve problems such as inaccurate detection results

Active Publication Date: 2015-02-11
ELECTRIC POWER RESEARCH INSTITUTE OF STATE GRID NINGXIA ELECTRIC POWER COMPANY +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] One of the purposes of the present invention is to provide a fault detection method for the outgoing line of a wind farm to solve the problem of inaccurate detection results in the prior art due to non-power frequency fault currents

Method used

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  • Fault detection method for circuit sent out from wind power plant
  • Fault detection method for circuit sent out from wind power plant
  • Fault detection method for circuit sent out from wind power plant

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0026] Step 1: After the fault start module is started, collect the phase current I at the installation place of the line protection sent out from the wind farm through the current transformer A , I B , I C ;

[0027] Step 2: Pass the collected current signal through a low-pass filter to filter out high-order harmonics, and enter step 3 after 0.01s;

[0028] Step 3: Use the least squares fitting method to construct a linear relationship between measurements and estimate the frequency f of the measured signal;

[0029] Step 4: Judging the difference between the frequency f and the system power frequency 50Hz, if they are approximately equal within 0.01s, then go to step 5; Protect the relay and return to step 3;

[0030] Step 5: Use the existing distance protection based on the full-circumference Fourier algorithm to judge the action of the distance protection.

[0031] The details of step 1 are as follows, taking the phase A current as an example:

[0032] After a fault ...

Embodiment 2

[0056] Such as figure 2 As shown, a doubly-fed wind farm simulation model with 50MW installed capacity is given, the positive sequence impedance of the system is 1.0914+j12.45Ω, and the zero sequence impedance is 5.187+j 22.574Ω. When a three-phase fault occurs on the line at f1, the bus voltage on the wind farm side drops to 20%.

[0057] Methods include:

[0058] Step 1: After the fault start module is started, collect the phase current I at the installation place of the line protection sent out from the wind farm through the current transformer A , I B , I C ,Such as image 3 shown;

[0059]Step 2: Pass the collected current signal through a low-pass filter to filter out high-order harmonics, and enter step 3 after 0.01s;

[0060] Step 3: Use the least squares fitting method to construct a linear relationship between measurements and estimate the frequency f of the measured signal. The frequency results calculated at different times are as follows Figure 4 shown; ...

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Abstract

The invention discloses a fault detection method for a circuit sent out from a wind power plant. The method comprises the following steps: 1 collecting phase current of a circuit sent out from a current wind power plant after a fault appears; 2 building a linear relationship between measurement by using the least squares fitting method, and estimating the frequency of the phase current; 3 when the calculated frequency of the phase current is in a normal frequency range, judging that a crowbar protection circuit is not started, and entering the step 4; or else, judging that the crowbar protection circuit is started, and returning to the step 1; 4, finding out the position of sending out the fault in the circuit through a distance protection element. The fault detection method can be immune to non-power frequency current characteristics sent out from a double-fed wind power plant; the operation characteristics of fault impedance and distance protection can be quickly calculated aiming at various fault types; the protection reliability and selectivity are greatly improved.

Description

technical field [0001] The invention belongs to the technical field of fault detection, in particular to a fault detection method for a transmission line of a wind farm. Background technique [0002] At present, doubly-fed wind turbines have been widely used in the field of new energy power generation. Distance protection, as one of the mainstream backup protections, plays an extremely important role in the safe operation of wind farm transmission lines. When the grid voltage drops and the rotor overcurrent is caused by the doubly-fed wind turbine, in order to protect the converter on the rotor side, the crowbar (crowbar) protection circuit will be put into operation. At this time, the stator terminal will send a non-power frequency fault current to the grid. It has brought many practical engineering problems to relay protection, one of which is that the distance protection element based on Fourier algorithm cannot accurately calculate the impedance from the fault point to t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26
Inventor 张爽黄永宁郝治国张军焦龙田蓓
Owner ELECTRIC POWER RESEARCH INSTITUTE OF STATE GRID NINGXIA ELECTRIC POWER COMPANY
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