Intelligent transformer station transformer ratio differential protection false operation prevention method

Abstract

The invention relates to an intelligent transformer station transformer ratio differential protection false operation prevention method. The method comprises steps that AC digital sampling values of each side of a transformer are acquired by a microcomputer relay protection device and are further transmitted through a data bus to a protection module, and the original sampling values and the fundamental amplitude obtained through calculation are stored in the protection module; the middle and low voltage side current of the transformer is converted to the high voltage side current through the AC digital sampling values of each side and the fundamental amplitude, and the fundamental differential current of each phase of the transformer, the fundamental braking current, the sampling value differential current and the sampling value braking current of the transformer are calculated; the calculation results are processed; data window point sampling is carried out according to the processingresult, if an S point of R points of a data window satisfies the processing result, a sampling value differential protection motion sign is outputted; AND logic is employed to determine the operationresult and the sampling value differential protection motion sign, if conditions are satisfied, a final protection motion outlet sign is outputted. The method is advantaged in that when main transformer sampling encounters relatively large DC components or is disturbed during operation, differential protection false operation of a flying spot is prevented, and relay protection reliability is improved.

Description

technical field [0001] The invention relates to a method for relay protection of an electric power system, in particular to a method for an intelligent substation to prevent maloperation of a transformer ratio differential protection caused by flying spots of alternating current and direct current components. Background technique [0002] With the promotion of smart substations and the emergence of new protection principle devices based on smart grids, the number of projects using digital access protection devices has increased. The flying point data of electrical quantity sampling in the power system (abnormal sampling data on the continuous smooth electrical quantity sampling curve, hereinafter referred to as "flying point" such as image 3 Shown) The phenomenon of misoperation of protective devices is gradually increasing. Although the flying point criterion and processing in the collection process can filter it to a certain extent, it cannot completely eliminate the infl...

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Problems solved by technology

[0004] The fast action of protection requires that the flying point detection delay must be very short, but it is very difficult to accurately distinguish the flying point sampling data from the normal transient sampling value when the system fails within a short detection data window

Since the construction time of the smart grid is not long, there are currently few detection methods for abnormal sampling such as flying points. At the same time, these methods have some shortcomings, such as poor pertinence, low sensitivity, difficult threshold setting, and long data window requirements. , poor real-time performance, unable to apply fast protection, easy to misjudgment, etc.

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