The Use of IEC61850-9-2 (Sampled Values) and 61850-8-1 (Goose Messaging) In a Small Rural Substation

摘要

Orion has a programme of upgrading switchgear and protection at older rural substations. These substations are typically equipped with a single 7.5/10 MVA transformer and supply four or five 11 kV feeders. In some cases both the switchgear and protection was being replaced, in others just the existing electromechanical protection. This was an opportunity to explore the use of IEC61850 as a method of upgrading and improving the substation control and protection systems while significantly simplifying the physical installation. The GE Hardfiber system was chosen to provide the protection and control functions with IEC61850 Merging Units (Bricks) being mounted on or near the primary plant and the protection relays/intelligent electronic devices (IED's) mounted remotely on a separate relay panel. This allows the use of conventional instrument transformers but with very short secondary copper cabling to the Bricks. IEC61850 Sampled Values were used to return real time system analogue values to the protection relays/IED's using Ethernet over point to point fibre connections - otherwise known as the IEC61850 Process Bus. Goose Messaging via the Process Bus was used to provide inter relay signalling for transfer tripping, circuit breaker fail initiation etc. The final design required only three protection relays/IED's for a substation with one 7.5/10 MVA transformer, 33 kV HV breaker, 11 kV incomer breaker and five 11 kV feeder breakers. It provided duplicate feeder protection, low impedance 11 kV bus zone, full transformer differential protection and breaker fail protection. Advantages of the design include very much simplified protection relay/IED panels and virtually no copper cabling (and wiring blocks). It also allows for very much simplified future modifications to the substation requiring virtually no additional protection panel wiring.