Bus protecting method based on relevancy of virtual electric currents
A technology of virtual current and busbar protection, applied in emergency protection circuit devices, electrical components, etc., can solve the problems of being susceptible to interference, protection misoperation or refusal, and uncertain protection action boundaries, so as to improve accuracy and rapidity. , the effect of eliminating high frequency components
Active Publication Date: 2015-07-15
NARI TECH CO LTD +1
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Problems solved by technology
However, the protection action boundary is uncertain, there is a certain range of fuzzy areas, and it is easily affected by interference. If the setting is not appropriate, it may lead to misoperation or refusal of protection. The anti-interference ability and reliability of its protection need further research
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[0031] The present invention will be described in further detail below with reference to the accompanying drawings.
[0032] figure 1 It is a schematic diagram of the connection of each branch of the power system bus system of the present invention. Such as figure 1 As shown in , it is assumed that the busbar system consists of n branches, and the branches include bus tie circuit breakers, lines and / or transformers. The A, B, and C three-phase currents of each branch on the bus are sampled at a constant sampling frequency. The analysis in this embodiment takes 40 points / cycle as an example for sampling (for a 50Hz power system, a cycle is 20ms). Take 5ms sampling value data after the fault occurs, and carry out rolling integration processing on the current sampling value of each branch at each sampling point. For example, for the current sampling value of the nth branch, when the sampling point is k, this point The data rolling integral can be calculated by the following f...
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The invention discloses a bus protecting method based on the relevancy of virtual electric currents, and belongs to the technical field of electric power systems and automation thereof. The bus protecting method disclosed by the invention comprises the following steps: performing sampling on each branch according to a fixed sampling interval; performing rolling integral processing on the sampled current value of each branch at each sampling point, wherein the processing results are used as a basis for judging the polarity of the branch current; combining sampled values obtained at the same time so as to simplify the multi-branch bus system into a simple bus which only has virtual currents flowing in and out; continuously calculating the relevancy of waveforms of virtual currents by utilizing short data windows according to the characteristic difference of the waveforms of virtual currents under different running states of the bus, and distinguishing internal and external faults of bus areas according to the distributing situation of values according to the multi-point relevancy. Through the adoption of the bus protecting method disclosed by the invention, the internal and external faults of bus areas can be quickly and reliably judged without being influenced by the fault types or the transition resistance of faults; the bus protecting method is resistant to TA saturation and frequency deviation, so that the accuracy and the rapidity of action are improved.
Description
technical field [0001] The invention belongs to the technical field of electric power systems and automation thereof. More precisely, the invention relates to a relay protection method for a busbar system. Background technique [0002] The busbar is an important part of power plants and substations. Once a fault occurs, it will seriously affect the normal operation of other electrical equipment connected to the busbar, resulting in a large-scale power outage. At present, the key to the correctness of busbar protection operation is the saturation of external fault current transformers. Although relay protection workers have proposed various criteria and methods for detecting current transformer saturation, which have solved the influence of current transformer saturation on busbar protection to a certain extent, there are still many problems caused by current transformer saturation in actual operation. And lead to the serious situation of protection false action and refusal ...
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Inventor 李肖博罗剑波谭凌李雪明揭萍陈汹郝后堂朱开阳
Owner NARI TECH CO LTD