A Transformer and Inrush Current Identification Method Based on Online Voltage Integration
An identification method and transformer technology, applied in electrical components, emergency protection circuit devices, etc., can solve problems such as differential protection malfunction, current transformer saturation, complex characteristics, etc., to ensure safe and stable operation, prevent malfunction, improve The effect of action performance
Active Publication Date: 2018-01-12
STATE GRID CORP OF CHINA +1
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Problems solved by technology
However, due to the characteristics of strong concealment, various forms, and complex characteristics of the inrush current, it is also easy to cause saturation of the current transformer, which may lead to the failure of the traditional inrush current identification criterion and cause differential protection misoperation.
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[0042] The technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention.
[0043] The present invention provides an embodiment of a transformer and inrush current identification method based on online voltage integration, which includes the following steps:
[0044] Step 1: Read the sampling value of transformer current and voltage;
[0045] Step 2: Calculate the magnitude of the current mutation according to the read transformer current sampling value, and then judge whether to start and recognize the inrush current according to the magnitude of the current mutation. The startup criterion of the mutation is
[0046]
[0047] where ΔΔI set is the starting threshold, ΔΔI set >0, i(k) is the sampling value of the kth point of transformer excitation current, k represents n or N is the number of current sampling points in one power frequency cycle, and as a preferred embodi...
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The invention provides a method for identifying sympathetic inrush current of a transformer based on online voltage integrating. The method comprises the following steps: step 1, reading current and voltage sampling values of the transformer; step 2, judging whether to start sympathetic inrush current identification or not; step 3, calculating the magnetic flux of the transformer; step 4, calculating the amplitude of the magnetic flux of the transformer; step 5, judging flux saturation on line; step 6, carrying out adaptive adjustment on the fixed value of a differential protection action platform; and improving the original fixed value of the action platform operating transformer differential protection to k1 times higher than the original fixed value, wherein k1 is more than 1. The method disclosed by the invention is not subject to the effects of sympathetic inrush current type and saturation of a current transformer, which prevents false action of transformer differential protection during the generation of sympathetic inrush current and facilitates the engineering application.
Description
technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for identifying transformers and inrush currents based on online voltage integration, which can be used to prevent maloperation of transformer differential protection due to inrush currents. Background technique [0002] The transformer is one of the most important electrical equipment in the power system, and its operation safety is directly related to the safe and stable operation of the power system and the reliability of power supply. Differential protection is widely used as the main protection for transformers, which is characterized by fast action speed and good selectivity, but it is easily affected by inrush current and malfunctions. At present, many studies have been carried out on the inrush current, and some preventive measures have been put forward, such as strengthening the second harmonic criterion (see Zheng Tao, Zhao Ping. ...
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IPC IPC(8): H02H7/045
CPCH02H7/045
Inventor 张侃君尹项根夏勇军张哲周友斌胡伟戚宣威陈堃张时耘文博曹文斌黎恒烜杜镇安叶庞琪雷扬
Owner STATE GRID CORP OF CHINA