Interfacing IEC 61850 Station Bus Protection to Existing Protection in a Brown-field Substation
When retrofitting an in-service substation with IEC 61850 station bus protection, it is not always practical to de-energize the entire substation to install new equipment. In most projects, an outage schedule will be developed to plan when primary system components will be taken out of service and subsequently returned to service with the newly commissioned protection. When upgrades are done one outage at a time, it results in an IEC 61850 scheme with networked trips, adjacent to an existing protection scheme using lockouts and wired trips. Some means of interfacing between the two schemes must be incorporated into the design. Subsequent outages will upgrade the adjacent scheme to IEC 61850, requiring a plan to migrate the protection from one configuration to the next. This paper presents an example of an installed IEC61850 station bus scheme interfaced with existing traditional protection utilizing a protection interface device. It explains the development of the migration plan process, and the advantages of developing a single configuration for a protection interface device to accommodate all steps of the protection scheme migration.