Overview
IEC TS 62786:2017 - Distributed energy resources connection with the grid is an IEC Technical Specification that defines principles and interface requirements for connecting distributed energy resources (DERs) to medium-voltage (MV) and low-voltage (LV) distribution networks. Applicable to systems operating at a nominal frequency of 50 Hz or 60 Hz, the document covers planning, design, operation, connection and conformance testing for DERs such as synchronous and asynchronous generators, converter-interfaced generation and permanently connected electrical energy storage.
Key Topics
This technical specification organizes practical technical requirements and tests into clear topic areas, including:
- General requirements and connection scheme - recommended arrangements for point(s) of connection and interface switchgear.
- Choice of switchgear and interface switching - selection and operational considerations for protective and isolation devices.
- Normal operating range - permitted operating frequency and voltage ranges during normal and limited conditions.
- Immunity to disturbances - requirements for ROCOF (rate of change of frequency), under-voltage ride-through (UVRT) and over-voltage ride-through (OVRT) capabilities.
- Active power response to frequency deviation - how DERs should respond to system frequency changes to support stability.
- Reactive power and voltage control - reactive power response characteristics and dynamic support for voltage variations and steps.
- EMC and power quality - emission limits, DC injection control, flicker and harmonics considerations.
- Interface protection - specified protection functions and coordination with distribution system operator (DSO) requirements.
- Connection, start-up and auto-reclose - safe connection procedures including synchronous generator specifics and reclosing practices.
- Active power management, monitoring, control and communication - supervisory control, telemetry and interoperability requirements.
- Conformance tests - test methods and normative annexes for validating UVRT/OVRT, frequency/voltage ranges and other interface behaviors.
Applications
IEC TS 62786:2017 is intended for practical use in:
- DER manufacturers (inverter and generator design)
- Distribution System Operators (DSOs) and planners for grid integration rules
- System integrators and EPC firms deploying DERs and storage
- Test laboratories and certification bodies performing conformance testing
- Regulators and network operators developing connection agreements and technical codes
Using this TS helps ensure DERs provide predictable frequency and voltage support, comply with EMC/power quality limits and integrate safely into distribution networks.
Related Standards
Normative references in IEC TS 62786:2017 include:
- IEC 61000 series (Electromagnetic compatibility)
- IEC TS 62749 (Assessment of power quality)
Note: this Technical Specification can be superseded by national regulations. Future editions may extend scope (e.g., mobile storage/EVs).