| The bus difference and failure protection devices are important relay protection devices to ensure the safe and stable operation of the power grid.The bus protection and the failure protection play an important role in ensuring the power supply reliability of the power grid.In recent years,the parental error and failure protection devices have been continuously updated.At the same time,China's technical specifications for relay protection devices have been continuously improved,from the early "four unifications" to rapid changes to "six unifications",and eventually changed to "new six unifications"(also known as "nine unifications").Due to the rapid replacement of relay protection devices and the continuous improvement of technical regulations and norms,the bus difference and failure protection devices in the early construction and operation of substations in China are in urgent need of transformation.The 220 kV HD substation is an important hub substation in the eastern part of Harbin which is connected to the 500 kV Yongyuan power station,220 kV Taiping and 220 kV Moli stations and plays an important power distribution hub role.The construction of the bus difference and failure protection device in the station was put into operation in September 2006.Its software and hardware level has not met the requirements of the latest technical regulations and specifications of China's relay protection.There are many problems and urgently need to be reformed.In response to this problem,it is urgent to study and formulate a set of transformation plans.In order to carry out the research on the transformation plan,first introduce the principle and logic structure of the mother differential and failure protection,and focus on the principles of ratio differential,double ratio differential and failure protection.Secondly,the common bus connection methods are introduced,and the 220 kV bus in the 220 kV HD substation is a double-bus single-segment with bypass wiring method.The 220 kV bus difference and failure protection configuration are two sets of bus difference protection,and the single failure protection set Configuration,separate configuration of mother difference and failure protection.Through technical investigation again,it was found that the problems of 220 kV bus difference and failure protection in the station include: the protection configuration does not meet the integrated configuration requirements of different manufacturers without the principle,the double sets of bus difference and failure protection take the same DC power supply,and the DC independent requirements are not met.The defects of the bus difference and failure protection logic and the construction of the secondary circuit do not meet the requirements of the latest technical specifications,and corresponding solutions are formulated for these three problems.In addition,the corresponding transformation plan is formulated and implemented in combination with the solution.The transformation plan mainly includes the formulation of the power outage operation plan and the renovation project.The power outage operation plan clarifies the power outage sequence and the operation content of the corresponding power outage branch.According to the failure function of the two sets of bus differential protection The sequence of verification,bypass and the original set of bus differential protection secondary circuit changes,No.1 and No.2 main transformers,9 lines,bus couplers and segmented secondary circuit changes are carried out in sequence.The reconstruction project explained the technical realization method in detail,and upgraded the protection logic through the replacement of the protection device.Through the change of the automatic point table and point number link source to ensure the consistency of the status of the background and protection knife gate.Through the change of the relevant functional logic and circuit of the protection device,the function of bus difference and failure protection is realized and perfected.The specific changes mainly include: protection logic changes,protection function input,automation,DC power supply,AC,knife gate,trip and start failure circuit changes.Finally,the accuracy of the reconstruction project is verified by protection debugging,and the above technical problems in the protection configuration,DC power supply independence,protection logic and related secondary circuits in the original 220 kV bus difference and failure protection in the station are solved,and the integration of bus difference and failure protection is realized The configuration,dual sets of protection power sources are independent,the standardization and standardization of the secondary circuit and the secondary circuit of the failure protection,completely eliminate the potential safety hazards caused by technical problems.After the transformation is completed and put into operation,the 220 kV bus difference and failure protection in the station are in good condition.In this study,through the reasonable formulation of the power outage plan,the power outage time and power outage range were shortened.Due to the introduction of the split pressure plate,when the operation mode of the bus in the station changes,the operation of the 220 kV bus difference and failure protection in the station is more flexible and safe and reliable.Through the upgrade of the protection device,when the short-circuit fault of the 220 kV HD substation bus and the main transformer malfunction,the protection function is continuously improved,the protection sensitivity is enhanced,the protection action speed is further increased,and the background information of the main station is stationed.Through the rational use of some old cables,the cost of the transformation to protect the secondary circuit was saved,and the research on the transformation plan was completed.The research results can be extended to other substations with similar bus difference and failure protection configuration in Harbin. |
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