IEC/TS 62898-3-4 Ed. 1.0 en:2023 PDF

The purpose of this part of IEC 62898 is to provide technical requirements for the monitoring and control of microgrids. This document applies to non-isolated or isolated microgrids integrated with distributed energy resources. This document describes the specific recommendations for low-voltage (LV) and medium-voltage (MV) microgrids.

This document focuses on standardization of the architecture, functions, and operation of microgrid monitoring and control systems (MMCS). It teases out the general functions of MMCS and provides technical requirements for MMCS. This document includes the following aspects of MMCS:
• system architecture,
• information exchange with other devices/functions in microgrid,
• performance requirement,
• main function descriptions.

The system architecture for MMCS:
• For a large scale (installed power > 100 kW) microgrid, microgrid energy management system (MEMS) and MMCS are normally separated. MMCS normally contains data servers, application servers, workstations, routers, information safety devices, SCADA, communication system, distributed generation controller, microgrid central controller, load controller, grid connection interface device and other ancillary equipment.
• For a small user-side microgrid (normally less than 100 kW), MEMS and MMCS are normally merged into one embedded device with system on chip, which is named as microgrid controller.

Main functions of MMCS:
• Data acquisition and processing, including collecting real-time data from the distributed generation, load, switches, transformers and reactive power compensation devices, and calculation and analysis of the acquired data.
• Database management, including maintaining, synchronizing, backing up, restoring the acquired data, and providing the data interface with other internal and external applications.
• Human-machine interface, including the real-time monitor screen and interface which is capable of remote control, mode switching, manual data entry, etc.
• Anti-maloperation locking and alarm, to lock the maloperation based on the predefined rule and logic.
• Time synchronization, including receiving the time synchronization signal from Global Navigation Satellite System (GNSS) or network time protocol (NTP) and synchronizing the time of each device within the microgrid.
• Local power quality evaluation and control the ability to collect information of out-of-limit voltage, power factor, harmonic, etc. and carry out control to improve power quality accordingly.
• Frequency/voltage regulation during steady state operation of an isolated microgrid to provide voltage and frequency inside an accepted operation range.
• Sequence of operations, or steady transition from power-off to start-up and from start-up to power-off.
• Switch control of devices within microgrids, including turning on and off loads, generation units, transformers, reactive power compensation devices, etc.
• Islanding detection, including real-time detection on power outage of the upstream distribution system.
• Operation mode transition, including transition from grid-connected mode to island mode and transition from island mode to grid-connected mode.
• Active and reactive power control, including load shedding (if required), load sharing and controlling the active and reactive power in real time according to the MEMS or manual command.
• Black start, the ability to initiate power sources and loads to ensure the microgrid can initiate
operation from a non-energized state.
• Interface with the protection system or earthing system when adaptations are required
according to the microgrid operating modes.