Medium-voltage bus differential protection device

Abstract

The invention provides a medium-voltage bus differential protection device. The device comprises a plurality of branch current acquisition units, a differential protection unit and a CT monitoring andselecting device. The output end of each branch current acquisition unit is connected with the differential protection unit, and an incoming line of a bus is connected with the differential protection unit through a CT. A secondary side split-phase current and a secondary side zero sequence current of a plurality of load branches CT penetrate into the corresponding branch current acquisition units in a mode of the same polarity for electromagnetic confluence, and the branch current acquisition units send the generated electromagnetic confluence into the differential protection unit. A currentof the incoming line is inputted to the differential protection unit, and the differential protection unit carries out bus fault judgment and CT broken line blocking bus differential protection according to the current of the incoming line, the electromagnetic confluence of a split-phase current and the electromagnetic confluence of a broken line current. A CT monitoring selection and judgment device carries out disconnection judgment according to a secondary side zero sequence current of the load branch CT. The differential protection of the medium-voltage distribution buses with a large number of intervals can be realized, and the load rate of a bus differential protection CPU is greatly reduced.

Description

technical field [0001] The invention relates to differential protection technology, in particular to a medium-voltage bus differential protection device. Background technique [0002] According to statistics, there are nearly 2,000 generating units of 300MW and above in my country, and the total capacity of 10kV users in the country is about 2.917 billion kVA. It is estimated that there are about 100,000 sections of 10kV (6kV) busbars on the power grid and power plant side. Therefore, medium voltage busbars play a pivotal role in the distribution network structure. However, the existing medium-voltage power distribution busbars are not equipped with mature fast protection devices, and the short-circuit current level of the busbar is relatively high, and the load switch operation is frequent, which is prone to short-circuit faults, and once a short-circuit fault occurs, it is easy to cause severe burning of the busbars Vicious accidents, repair failures as long as several mo...

AI Technical Summary

Problems solved by technology

However, the existing medium-voltage power distribution busbars are not equipped with mature fast protection devices, and the short-circuit current level of the busbar is relatively high, and the load switch operation is frequent, which is prone to short-circuit faults, and once a short-circuit fault occurs, it is easy to cause severe burning of the busbars Catastrophic accidents, repair failures can take months

[0003] Conventional busbar differential protection device, due to its limited number of intervals, in the case of general three-phase CT (current transformer), only meets the requirements of less than 26 intervals, and is not suitable for buses with too many intervals in each section of medium voltage

In addition, if there are too many intervals, the CPU occupancy rate will be too high, which will affect the speed, reliability and stability of the device.

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