Self-adaptive sampling delay compensation method of differential protection

Abstract

The invention discloses a self-adaptive sampling delay compensation method of differential protection. Two line differential protection devices are installed at two sides of a line; the protection device at one side of the line samples through an electromagnetic transformer; and the protection device at the other side of the line is connected to a merging unit and samples through an electronic transformer. The protection device connected with the merging unit acquires the sampling delayed time of the merging unit from the communication messages of the merging unit, and when a communication link is conducted for the first time, the protection device connected with the merging unit records the sampling delayed time in the communication frames and then saves the sampling delayed time to be used as the basis for time difference compensation. When the communication link is disconnected and then reconnected, the sampling delay in the communication frames is verified and is compared with the originally recorded data; if the sampling delay is consistent with the originally recorded data, approval is given to the sampling delay; and if the sampling delay is not consistent with the originally recorded data, an alarm is given and differential protection is quitted. The self-adaptive sampling delay compensation method of differential protection can be flexibly applied in various occasions with the mixed applications of the electric transformer and the electromagnetic transformer at the two sides of the line, and is suitable for various types of transformer substations.

Description

technical field [0001] The invention relates to an adaptive sampling delay compensation method in the application process of current differential protection in intelligent substations and conventional substations. Background technique [0002] At present, a large number of conventional electromagnetic current and voltage transformers are used in the substation, which are connected to the protection device through cables. During the data transmission process, there will be no data delay. With the vigorous development of smart grids, especially intelligent substations, after a large number of electronic transformers are applied, the sampled data is collected by remote modules, sent to the merging unit for merging, and then transmitted to the protection device through optical fibers. In this process, the sampling data is processed by many devices and transmitted through various connection methods, so there will inevitably be data delays. [0003] The principle of differential ...

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Problems solved by technology

[0004] like figure 1 As shown, when electronic current transformers are used on one side of the line and conventional electromagnetic current transformers are used on the other side, there will be a large amount of delayed intermediate links (including remote Low-pass, data processing, sending delay and transmission delay of the module, data receiving, processing, sending delay, sampling value transmission delay of the merging unit, etc.), different networking methods, and the use of different transmission protocols lead to sampling The uncertainty of the delay, while the conventional transformer has no other delay time link except the transmission angle difference. It is precisely because of the difference in the delay time between the electronic transformer and the conventional transformer that the time difference of the sampling waveform is caused, giving the differential Protected applications create new problems

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