IEC 61850 and SCADA systems

Many of today's substation devices like protection relays are IEC 61850 compatible - one way or the other. From a SCADA point-of-view these and other devices can easily interface with such devices using the client/server communication services:

• Get a value of single data object (GetDataValues – Client driven)
• Get a list of values of data objects (GetDataValues with list sent in each request – Client driven)
• Get the complete list values of data objects using a dataset object (GetDataSetValues – Client driven)
• Get the complete list of values of data objects (of a dataset) using reporting (reporting, General Interrogation – Client driven)
• Get the complete list of values of data objects (of a dataset) using reporting (reporting, Integrity period – Server driven)
• Get one (BufTm=0) or more (BufTm>0) value(s) of data objects (of a dataset) using reporting on data and quality change and data update – Server driven)
• GOOSE and Sampled Values … exchanges complete list of values of data objects of a dataset (events: application specific – Server driven
• Get sequence of value(s) of data objects (of a dataset) using logging (on data and quality change and data update – Client driven)

These IEC 61850 services (except for GOOSE and SV) are mapped to the MMS protocol.

In IEC 61400-25-4 the IEC 61850 services are mapped to:

• IEC 61950-7-2 ACSI and Information Models (LD, LN, DATA, DA, …) defined as webservices (almost all service in IEC 61850 become a corresponding WS in 61400-25-4)
• (full) Mapping according to IEC 61850-8-1 MMS
• (subset) Mapping to OPC XML DA
• (small subset) Mapping to IEC 60870-5-104
• (small subset) Mapping to DNP3

In the current scenario what should a SCADA vendor support in order to interface with 61850-compatible devices?

In existing installations with DNP3 or IEC 60870-5-101/104 it is recommended to keep these solutions. It is not recommended to just replace one protocol by another! IEC 61850 should be considered if SCADA systems want to benefit from the 3000+ standard information models and the substation configuration language (SCL, IEC 61850-6) to simplify the configuration of Gateways, RTUs, Data Management Systems, and SCADA systems and to simulate easily the Gateways, RTUs, and Data Management Systems!! Direct access from SCADA systems to IEDs may be required. Some utilities get rid of HMIs in Substations and provide IP access directly from the control center to the IEDs (trough routers).

EMS and SCADA systems of the big vendors have already or will have soon direct access to IEC 61850 compliant devices or systems. More to come soon.