Research On Power Grid Operation And Control Technology Adaptive To High Temperature Superconducting Cable Access

Compared with common cables,high temperature superconducting(HTS)cable has many advantages including large transmission capacity,low power loss,compact structure and low effect of environment.It is suitable for high density load supply in modern cities and largescale power transmission in power grid.Nowadays the HTS cable has gradually developed from experimental research to engineering pilot application.The HTS cable brings many problems and challenges to the operation control of the power grid because that its operation characteristics are different from conventional cable.The study of the paper is based on the project of China southern power grid company called “research on the operation mode and protection and control technology of the power grid suitable for the superconducting cable access”.The work bases on the engineering practice and systematically focuses on the parameter calculation of the HTS Cable,power flow control and analysis of loop closing current as well as automatic switching control of the network with HTS Cables.The work is aimed at providing guidance and suggestions to the popularizing application of HTS cable.The calculation of electrical parameters of HTS cables is an important basis for the research of power grid operation control of HTS cable.According to the structural features and electromagnetic coupling,mathematical models based on branch parameter method for three typical configurations of HTS cable are established and a method for calculating the electrical parameters of HTS cables is proposed.The correctness of the method is verified by comparing the simulation result with the calculation result.According to the characteristic that the resistance of HTS cable will change afer quench,the resistance calculation method considering quench is proposed.Based on the above study,the simulation modeling considering resistance change of the HTS cable after quench is established.The simulation modeling provides a powerful simulation analysis tool for study on quench characteristics of HTS cables.According to the demonstration project,the power optimization and control methods after different closed loop operations are analysed.A power flow optimization method is proposed to reduce the network loss by adjusting transformer taps.Effectiveness of the method is verified by simulation calculation.The paper also analyses the characteristics of loop closing surge current theoretically and proposes calculation method.The aximum phase angle difference of the port voltages is proposed which can ensure the HTS cable safe operation.As a result,the safety after different closed loop operations of different loads is verified.The analysis conclusion has a good guiding role for practical engineering application.Based on the present situation that the traditional automatic bus changeover can’t meet the demand of power supply reliability after the large capability HTS cable accessing substations with multi sectionalized bus wiring,a automatic bus changeover using multi interval information is proposed.The method can chose the suitable standby power supply according to the load margin of the backup power supply,the load level of the power loss bus and number of bus sections.It can improve the posibility of service restoration in power grid.The paper analysis the action result after the automatic bus changeover in a substation of the demonstration project.The result shows that the method is suitable for different faults and can make the buses losing power match appropriate power sources,which can reduce the risk of power loss and improve the reliability of power supply.