Method for single-phase earth fault line selection of neutral non-grounding power grid
A single-phase grounding fault, neutral point ungrounded technology, applied in the fault location, detecting faults according to conductor types, measuring electricity and other directions, can solve the problems of small steady-state components, complex data processing, difficult detection, etc. Small, simple fault criterion, and the effect of improving the speed of line selection
Inactive Publication Date: 2017-02-22
SHANDONG UNIV OF SCI & TECH
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Problems solved by technology
[0003] The line selection method based on steady-state quantities is prone to misselection due to weak ground fault characteristics and too small steady-state components
[0004] The line selection method based on transient quantities is difficult to accurately and fully extract the characteristic quantities after a fault, requires a large amount of complex fault data processing, is affected by the type of fault and the time of fault occurrence, and is susceptible to interference. The actual application effect is not ideal.
[0005] The intelligent line selection method can significantly improve the accuracy of line selection in theory, but it requires complex data processing, and the actual effect has yet to be tested
[0006] The S injection method breaks through the traditional line selection theory and adopts the method of actively injecting signals for fault line selection. This method requires additional equipment. When the grounding resistance value is too high, the injected signal is relatively weak and difficult to detect, and the fault cannot be accurately selected. line
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[0035] Embodiments of the invention are described in detail below, but the invention can be practiced in many different ways as defined and covered by the claims.
[0036] In order to overcome the limitations of existing line selection, the method for line selection for single-phase ground faults in neutral point ungrounded power grids proposed by this patent makes full use of the original fault data after the fault occurs for line selection, and the frequency distribution line graph shows the The overall distribution trend of the zero-sequence current data of the line, and the line is selected according to the frequency distribution value calculated by the Bessel formula.
[0037] refer to figure 1 It can be obtained that after a single-phase ground fault occurs in the neutral point ungrounded system, the magnitude of the zero-sequence current of the fault line is the sum of the zero-sequence current of all non-fault lines to ground, and the magnitude of the zero-sequence cu...
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The invention relates to a method for single-phase earth fault line selection of a neutral non-grounding power grid. The method is characterized by comprising the following steps: 1) monitoring a zero sequence voltage U0 of a power distribution network in real time and judging if the zero sequence voltage of the system is more than 0.15 times of a rated voltage UN of a busbar; 2) if yes, starting a line selection device to record a zero sequence current data in 1 / 2 power frequency period after the fault, and if not, returning to the step 1); 3) performing frequency distribution on the collected zero sequence current data of each line; 4) calculating a frequency distribution value of each line according to the data acquired through the frequency distribution and selecting the fault line according to the frequency distribution value. According to the method, the complex fault data treatment is not required, the original fault data after the fault happening is directly utilized to select the line, the method is more simple, reliable, accurate and quick than the other line selection methods and the engineering can be easily realized according to the method.
Description
technical field [0001] The invention relates to the technical field of power system fault line selection, in particular to a method for single-phase ground fault line selection of a neutral point ungrounded power grid. Background technique [0002] For a long time, experts and scholars at home and abroad have done in-depth research on single-phase ground fault line selection methods. The main methods are the line selection method based on the steady state quantity, the line selection method based on the transient quantity, the intelligent line selection method, and the S injection method. These line selection methods have their own line selection limitations. [0003] The line selection method based on steady-state quantities is prone to misselection due to weak ground fault characteristics and too small steady-state components. [0004] The line selection method based on transient quantities is difficult to accurately and fully extract the characteristic quantities after a...
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IPC IPC(8): G01R31/08
CPCG01R31/086G01R31/088
Inventor于群陈志慧曹娜
OwnerSHANDONG UNIV OF SCI & TECH