Inverse time limit overcurrent protection method based on impedance correction
An overcurrent protection and inverse time limit technology, applied in emergency protection circuit devices, electrical components, etc., can solve the problems of reduced quickness and increased delay of the backup protection section, and achieves the effect of good quickness and shortened action time.
Active Publication Date: 2020-01-31
CHINA THREE GORGES UNIV
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However, this scheme still uses the original inverse time-lag characteristic curve in the event of an out-of-area fault, but the access of the distributed power supply will increase the delay of the backup protection section of the upstream protection of the access point and reduce the quick action
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[0028] Such as figure 1 As shown, based on the inverse time overcurrent protection method based on impedance correction, when a fault occurs on the line, it is judged whether it is an internal fault or an external fault, and the impedance correction coefficient is determined in a targeted manner, and the line protection is calculated through the inverse time overcurrent protection action equation. The action time is to perform inverse time overcurrent protection on the line, and the inverse time overcurrent protection method based on impedance correction includes the following steps,
[0029] Step 1: Collect Z m ,Z line ,Z all , calculate Z=Z m / Z line , where Z m To protect the measured impedance, Z line For this line impedance, Z all is the impedance value of all lines downward from the protection installation, Z is the measured impedance percentage;
[0030] Step 2: According to the size of Z, judge whether the line fault is an internal fault or an external fault; ...
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The invention discloses an inverse time limit overcurrent protection method based on impedance correction. When a line fault occurs, whether it is an in-area fault or an out-of-area fault is judged and the impedance correction coefficient is determined accordingly. The impedance correction coefficient is introduced into an inverse time limit overcurrent protection action equation and the action time of line protection is calculated to perform inverse time limit overcurrent protection on the line. Whether the line fault is the in-area fault or the out-of-area fault is judged, the impedance correction coefficient is determined accordingly and the overcurrent protection of the out-of-area fault has better quick action performance. The impedance correction index is adopted to adjust the impedance correction coefficient, i.e. to adjust the correction degree of the inverse time limit characteristic curve so as to shorten the action time of the protection to the greatest extent on the premiseof ensuring the coordination relationship between the upper and lower protection.
Description
technical field [0001] The invention belongs to the field of relay protection for distribution networks, and in particular relates to an inverse time overcurrent protection method based on impedance correction. Background technique [0002] The action speed of inverse time overcurrent protection is easily affected by the system operation mode, fault type and line series. In addition, the widespread access of distributed generation (DG) also has an adverse effect on the selectivity and quick action of inverse time overcurrent protection. [0003] In response to the above problems, the current existing solutions mainly reflect the characteristics of the fault location according to the voltage or impedance, and introduce a voltage correction factor or impedance correction factor into the inverse time-limit action equation to correct the inverse-time characteristic curve to improve the protection speed. dynamic and selective purposes. The paper "Application of Low Voltage Acce...
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CPCH02H7/26
Inventor 黄景光张宇鹏杨鼎翁汉琍李江峡黄静梅郑钦杰
Owner CHINA THREE GORGES UNIV