Study on Substation Control Interlocking Combined with PKI/PMI Based Access Security Method

An improper switching operation can damage equipment and/or can affect the quality of supply to the customers. Normally, switches are opened and closed by operators using pre-generated guidelines for avoiding human errors. Software applications are used to automatically generate switching schemes which satisfy specified interlocking criteria. IEC 61850 proposed new requirement for switching operation such as Access control and interlocking. An applicable access control module had been designed in some papers known as PKI/PMI based substation access security method. Logical node CILO defined in IEC 61850 appears higher reliability and real-time efficiency on interlocking control, but the computation and store resources in IED are too limited to calculate interlocking rules inside. In this paper, we designed an interlocking method for CILO integrated with PKI/PMI based substation access security, a method of importing switching order rules into extension item of PMI attribute certificate via the customize interface to software applications in control center. The configuration of interlocking rules can be finished on getting access privilege simultaneously before operate. On the basis of information modeling for interlocking equipment, the construction of CILO, method of getting switchgear status, generation of interlocking result and distributed cooperation of interlocking control are analyzed. Finally, on the case study of an operation instance, this method can fulfill the function and Real-time requirements.