A small current grounding line selection method based on the principle of transient variation power direction
A technology of small current grounding and line selection method, applied in the direction of the fault location, etc., can solve the influence of the center point grounding mode of the steady-state signal method, the effect of line selection is not very ideal, and the multi-level ladder power supply coordination ground point location cannot be achieved, etc. problems, to achieve the effect of improving accuracy and line selection speed, high reliability and accuracy
Active Publication Date: 2017-12-19
BEIJING SIFANG JIBAO AUTOMATION +1
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Problems solved by technology
Among them, the transient signal line selection method currently used has not solved the problem of accurate transient state criteria; the steady state signal method is seriously affected by the system operation mode and the center point grounding method, and the line selection effect is not ideal; the injection signal method not only needs to add a device , and will add additional hidden troubles to the system, there are also problems of reliable transmission, acquisition and processing of injected signals, and the actual effect is not ideal, especially in special operating environments such as underground coal mines
More importantly, none of the above three types of methods can achieve multi-level ladder power supply coordinated grounding point positioning
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[0020] The present invention will be described in further detail below in conjunction with accompanying drawing and example.
[0021] The present invention specifically adopts the following technical solutions.
[0022] Below to figure 1 The power distribution network system shown is taken as an example, and the method for selecting the small current grounding line of the present invention is introduced. figure 1 As shown, the power supply is a step-down transformer whose neutral point is grounded through the arc-suppressing coil, with three busbars underneath, and each busbar has a load. according to figure 1 Real-time measurement of the zero-sequence current at the outlet of each line (3I 0 ) and bus zero-sequence voltage (3U 0 ), combined with the 3U0 steady-state value cross-limit criterion to determine the occurrence of a single-phase grounding fault, and accurately select the grounding line by comparing the zero-sequence transient power characteristic quantities of e...
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The invention discloses a small current grounding line selection method based on the principle of transient variation power direction. The method utilizes high-speed sampling zero-sequence current and zero-sequence voltage variation power, combined with 3U0 steady-state value over-limit criterion to determine occurrence For single-phase grounding faults, the grounding line is accurately selected by comparing the zero-sequence transient power characteristic quantities of each branch when a single-phase grounding occurs. The invention has high reliability and accuracy, is not affected by grounding mode and compensation device, does not need additional signal source, and improves the accuracy and speed of line selection.
Description
technical field [0001] The invention belongs to the technical field of relay protection and automation of power systems, and in particular relates to a small current grounding line selection method based on the power direction principle of transient variation. Background technique [0002] Since the small current grounding system will not generate a large short-circuit current when a single-phase ground fault occurs, and the line voltage between phases remains symmetrical, there is no need to disconnect the fault circuit immediately, and it does not affect the power supply to the load. my country's 6 ~ 66kV distribution network widely adopts the small current grounding method. However, if the system runs for a long time after single-phase grounding, the fault will easily develop into a two-point or multi-point grounding short circuit. Arcing grounding will also cause overvoltage in the entire system, which will damage the equipment and endanger the safe operation of the syste...
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IPC IPC(8): G01R31/08
Inventor 耿勇齐李继晟
Owner BEIJING SIFANG JIBAO AUTOMATION