Research And Application Of Improving Reliability Of Longitudinal Protection Channels

As an important part of ensuring the safe and stable operation of the power grid,the relay protection device itself must meet the requirements of reliability,selectivity,sensitivity and speed,and but also need transmission channel to accurately and quickly transmit the protection signal.The fault point can be removed in the shortest possible time to avoid the further expansion of the fault affecting the stability of the system,which puts high requirements on the reliability of the transmission channel.In the power grid operation,the relay protection signal is mainly transmitted through the SDH(Synchronous Digital Hierarchy)optical network.At present,the connection between the relay protection device and the SDH optical transmission device is not directly connected,but through the MUX-2MD(photoelectric conversion device)to achieve interface matching and SDH device connection.In practical applications,it is found that such relay protection signal transmission methods have complicated interface connection,many photoelectric conversion links,and poor channel stability.The power supply and grounding problems of the photoelectric conversion device may cause the protection device to malfunction of protection device and the reliability of the protection devices are reduced.And due to the photoelectric conversion device is not monitored by the network management system of the SDH optical transmission system,it bring great inconvenience to the debugging and troubleshooting of the communication department.In order to solve the above problems,this group proposes to develop an optical interface card,that develop a 2M optical interface card to directly transmit the2 M optical signal output from the protection device to the 2M optical interface of the SDH optical transmission device through the optical fiber channel.The use of intermediate photoelectric conversion equipment is reduced,which has great practical value for improving the stability of the relay protection communication system and the convenience of operation and maintenance.Research project group have developed2Mbit/s optical signal transmission devices based on 2Mbit/s optical interface standards,which are operated by the State Grid Shandong Electric Power Company.The verification work was conducted in the Smart Grid Lab of Shandong Electric Power Research Institute.The test includes 2Mbit/s optical interface parameter testing,network management monitoring function testing,interoperability testing,stability testing,and relay protection device hooking action test to verify The 2Mbit/s opticalinterface meets the requirements for interconnection and protection of relay protection devices and transmission equipment,and the relay protection device is based on whether the 2Mbit/s optical interface correctly responds to the protection action.According to the regulation of relay protection signal transmission quality in the current power dispatching and communication technology standards,the transmission error code characteristics and transmission delay of 2Mbit/s optical interface communication system have been calculated,measured and analyzed.The final result accords with the power standard specification.;And in the long-term test relay relay protection device can correctly respond to protection actions,no errors and alarms.The research in this dissertation proves that the reliability of the 2Mbit/s optical interface fully satisfies the transmission requirements of the relay protection signal,and can replace the current connection mode between the relay protection device and the SDH optical transmission device.