Online evaluation method for capacity of power distribution transformer

Abstract

The invention provides an online evaluation method for the capacity of a power distribution transformer. The method comprises a step of using a correlation coefficient method to realize the automaticidentification of a power distribution transformer connection group, a step of calculating Dyn11 distribution transformer short-circuit impedance and Yyn0 distribution transformer zero-sequence impedance and comparing the impedances with a standard reference value, and a step of finally obtaining a power distribution transformer evaluation capacity. According to the operating voltage data of the power distribution transformer, a correlation coefficient method is applied to realize the self-identification of the power distribution transformer connection group. Under the condition that the primary side electric quantity of the power distribution transformer cannot be obtained, the rated capacity of the power distribution transformer can be accurately evaluated by a Dyn11 distribution transformer capacity online evaluation method. Under the condition that a neutral point of a Yyn0 distribution transformer is offset, the rated capacity of the power distribution transformer can be accurately evaluated by a Yyn0 distribution transformer capacity online evaluation method.

Description

technical field [0001] The invention relates to an online evaluation method for distribution transformer capacity, which belongs to the technical field of transformer operation. Background technique [0002] In the power system, due to special needs, there is a problem of distribution transformers "filling large with small" or "filling small with large". In order to save costs, some manufacturers use small-capacity transformers to pretend to be large-capacity transformers. Electricity bills use large-capacity transformers as small-capacity transformers, so it is necessary to accurately grasp the actual capacity of distribution transformers to ensure the safe and economical operation of the distribution network. [0003] At present, the judgment of distribution transformer capacity mainly judges the actual capacity of distribution transformer by comparing the no-load loss or impedance voltage value with the national standard reference value, but it often needs to be carried o...

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Problems solved by technology

[0003] At present, the judgment of distribution transformer capacity mainly judges the actual capacity of distribution transformer by comparing the no-load loss or impedance voltage value with the national standard reference value, but it often needs to be carried out offline during the capacity test process, which affects the power supply of the distribution network Reliability, the existing method of online detection of distribution transformer capacity cannot be practical due to the huge number of distribution transformers that are actually connected to the grid. For example, the number of distribution transformers in operation in Jiangxi Company exceeds 200,000. , time-consuming and laborious, not suitable for large-scale use

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