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Some special applications of 220kV bypass breakers, Cai Baorui (Yunnan Power Group Co., Ltd., Kunming, Yunnan 650011, China) were analyzed and summarized. These methods have been widely used in the operation of Yunnan Power Grid, power grid operators, managers and designers.
Bypass breaker can be understood as a backup breaker. When the main breaker is out of service due to overhaul or abnormality, we can use the bypass breaker for the supply, without the need to power off the line. This is familiar to everyone. common. In fact, due to the special wiring of the bypass, the bypass circuit breaker still has many flexible applications in the operation and operation of the power grid. These contents are common in practical work, but few articles are devoted to discussion. The wiring method of the 220kV double bus with bypass is now discussed.
1 By using the bypass breaker to impact the new production line. For the line to be put into operation, the primary and secondary equipment have not been tested in actual operation, and the CT polarity and protection direction of the protection are not detected. In order to prevent the new line from failing when the new line is put into operation, its protection fails to operate correctly, and the accident is expanded. The bypass circuit breaker can be used to impact the new production line to ensure that when the line is faulty, the bypass circuit breaker is used. Can quickly break open the fault. After the line impact is normal, the circuit breaker of the line is put into operation.
Before the bypass breaker is used to put the new production line into operation, the protection setting of the bypass breaker should be set to the value of the new line. If there is no fixed value for the new line, according to the length of the line, select a line with the same length as the new line or the new line to meet the requirements of the "long line protection short line".
If the bypass circuit breaker is equipped with a latching high frequency protection, the high frequency protection can be put into operation, and the DC power supply of the high frequency protection transceiver on the opposite side of the line can be disconnected. In this way, the high-frequency protection of the bypass circuit breaker can play a full-line rapid protection function for the new line.
2 Detection of the protection direction of the newly-launched unloaded line 1) We often encounter such a situation. The newly-introduced line has no load or low load when it is put into production, and cannot meet the requirements of line protection direction and CT polarity detection. At this time, we can borrow the supply, so that the protection direction of the newly-produced circuit breaker can be detected. For the wiring method of the double busbar with bypass, the general operation is as follows: The circuit breaker material DL will be put into production! The remaining components of the same bus (such as IM) are placed on the same busbar DL2 to the other busbar.
The isolating switch GKi5 bypassing the production circuit breaker DLi is closed. (GK25 ​​is the ration) (Upper M) and the bypass bus is put into operation.
Pathway.
In this way, the load current of the DL2 line also flows through the DL! The line protection direction and CT polarity can be detected for DLi.
2) For this special operation mode, the protection considerations have the following points: 1 Before the bypass circuit breaker PD is put into operation, its protection setting needs to be accounted for. The protection range of the bypass breaker must be the full length of the new production line. In addition, the protection value of the bypass breaker from the three sections should be able to avoid the maximum load current of the DL2 line. This special mode has a short running time. For the sake of simplicity, it is usually also possible to use a set of protection settings for the long line to meet the protection of the bypass circuit breaker with sufficient sensitivity.
2 If the newly commissioned line fails in this special mode of operation, the bypass breaker PD may trip. It should affect the normal power supply of the DL2 line. Therefore, the selection of DL2 lines should be carefully considered. Generally, one of the double-circuit lines with less load is selected to reduce the threat to the normal power supply of the power grid.
3 The application of the bypass circuit breaker in the abnormality of the main circuit breaker 1) In the operation of the power grid, we often encounter abnormal or emergency defects of the circuit breaker. The common SF6 air pressure is low, and the operating mechanism pressure of the circuit breaker is low. It may cause the circuit breaker to be closed and closed. At this time, if the leakage is serious, the on-site personnel cannot handle it, and the maintenance personnel cannot arrive in time, they must find a way to stop the abnormal circuit breaker as soon as possible.
In the above case, the abnormal circuit breaker can be powered off by switching the remaining normal components to the other busbar and using the bus coupler and the line-side circuit breaker to power off the line. However, such operations have two major drawbacks. First, the operation time of the switching operation is delayed, and the processing time is delayed, which is particularly prominent for substations with more outlets. Second, the line needs to be powered off, and sometimes the power grid may not have the conditions.
This problem can be easily handled if bypass is used.
The general operation is as follows: a. Quickly put the bypass circuit breaker PD into operation, and supply the abnormal circuit breaker DLi (see the figure is in the running state. b. Because DLi is locked and closed, can not directly operate to disconnect DLi, can operate When the isolating switch GK6 is broken (equal potential breaking), and then the GIKi is disconnected, the DLi is powered off. c. When the isolating switch GK6 is broken, it is better to remove the closing insurance of the bypass breaker PD to avoid When the PD sneaked, it caused a load to pull the knife.
d For the operation of breaking the ring with the isolating switch GK6, due to the circulation, it needs to be accounted for and approved by the relevant production authority.
4 Summary above only for the double busbar with bypass wiring, listed some of the flexible use of bypass breakers when new equipment is put into production and when handling circuit breaker emergency defects. For other special wiring methods, such as single mother section with bypass, double busbar bus and bypass, double busbar bypass and busbar connection, the bypass still has many flexible uses, and also has special The requirements are worthy of everyone to think about and summarize.
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