3.7 Interoperability, DER Interconnection, and Communication Standards and Technologies

3.7.4 IEC 61850 as Information Model for DER

IEC 61850 was originally developed as an information model and protocol for substation automation. However, it became clear that this information model could be extended to cover DER systems and eventually the advanced “smart inverter” functionality as well.

The IEC 61850-7-420 standard on information models for distributed energy resources (DER) was published in 2009. It covers the management of DER systems as well as details on reciprocating engines, fuel cells, microturbines, photovoltaics, combined heat and power, energy storage, and other generation and storage systems connected at medium and low voltage levels.

IEC 61850-90-7 was published in 2013. It provides the information models for inverter-based DER functions, covering the following :

• Immediate control functions for inverters
• Function INV1: connect / disconnect from grid
• Function INV2: adjust maximum generation level up/down
• Function INV3: adjust power factor
• Function INV4: request active power (charge or discharge storage)
• Function INV5: pricing signal for charge/discharge action
• Volt-var management modes
• Volt-var mode VV11: available vars support mode with no impact on watts
• Volt-var mode VV12: maximum var support mode based on WMax
• Volt-var mode VV13: static inverter mode based on settings
• Volt-var mode VV14: passive mode with no var support
• Frequency-watt management modes
• Frequency-watt mode FW21: high frequency reduces active power
• Frequency-watt mode FW22: constraining generating/charging by frequency
• Dynamic reactive current support during abnormally high or low voltage levels
• Dynamic reactive current support TV31: support during abnormally high or low voltage levels
• Functions for “must disconnect” and “must remain connected”
• “Must disconnect” MD curve
• “Must remain connected” MRC curve
• Watt-triggered behavior modes
• Watt-power factor WP41: feed-in power controls power factor
• Alternative Watt-power factor WP42: feed-in power controls power factor
• Voltage-watt management modes
• Voltage-watt mode VW51: volt-watt management: generating by voltage
• Voltage-watt mode VW52: volt-watt management: charging by voltage
• Non-power-related modes
• Temperature-function mode TMP: ambient temperature indicates function
• Pricing signal-function mode PS: pricing signal indicates function to execute
• Parameter setting and reporting
• Function DS91: modify inverter-based DER settings
• Function DS92: event/history logging
• Function DS93: status reporting
• Function DS94: time synchronization
• Scheduled commands, in which a schedule is sent to the inverter with commands scheduled for particular times. These commands can also invoke pre-established parameters. Examples include:
• Week-day schedule for volt-var actions
• Weekly schedule for frequency-watt actions

The IEC 6150 information models have been “mapped” to different protocols:

• IEC 61850-8-1 MMS (Manufacturing Messaging Specification). It is the primary and most implemented mapping for substation automation
• IEEE 1815 (DNP3) and IEEE 1815.1 (DNP3 mapping to IEC 61850)
• IEEE 2030.5 (SEP 2.0 - Smart Energy Profile Application Protocol)
• IEC 61850-8-2 (pending) Web services (Extensible Messaging and Presence Protocol (XMPP), OPC/UA, or other).

The IEC 61850 information model has been selected as providing the basis for the communications required for the California SIWG Phase 1 and Phase 3 functions, while IEEE 2030.5 has been selected as the default protocol