Practical considerations of applying IEC61850 GOOSE based zone selective interlocking scheme in industrial applications

This paper gives an overview on the practical considerations when IEC61850 GOOSE messaging based Zone Selective Interlocking (ZSI) scheme is applied in industrial applications. Considerations are extended from normal instantaneous overcurrent (IOC) protection elements coordination, to timed overcurrent (TOC) protection elements coordination for both phase and ground protection, from one voltage level to multiple voltage levels, from ZSI schemes to fast bus tripping schemes. When transformer feeders are involved with a ZSI scheme, avoiding nuisance trip caused by transformer inrush current is a major concern that makes timed overcurrent protection to be used over IOC only. When motor feeders are involved with a ZSI scheme, motor lockout current need be considered, so timed overcurrent is also used instead of IOC element. The impact of different protection devices used in different motor circuits, breaker or contactor fuse combination is also discussed in the paper. Communication network plays an important role in IEC61850 GOOSE messaging based ZSI schemes. In consideration of ZSI blocking time, all influencing factors have to be taken into account. This includes breaker or contractor opening time, relay I/O response time and messages traveling time in the communication network. Reducing and separating network traffic by using advanced network technology is a key for the success. Communication network redundancy needs to be carefully considered and implemented as an important step in each stage of the project: in the early planning, the setup and the execution. Detailed arrangement and configuration of the switchgear and the motor control center is another factor to consider, in terms to accommodate the number of intelligent electronic devices (IEDs), which communicate using the technology available today.