IEC TS 62786-3:2023

Distributed energy resources connection with the grid - Part 3: Additional requirements for stationary battery energy storage system

IEC TS 62786-3:2023, which is a Technical Specification, provides principles and technical requirements for interconnection of distributed Battery Energy Storage System (BESS) to the distribution network. It applies to the design, operation and testing of BESS interconnected to distribution networks. It includes the additional requirements for BESS, such as connection scheme, choice of switchgear, normal operating range, immunity to disturbance, active power response to frequency deviation, reactive power response to voltage variations and voltage changes, EMC and power quality, interface protection, connection and start to generate electric power, active power management, monitoring, control and communication, and grid-connected tests.
The stationary BESSs considered within the scope of this document include electrical forms such as lead-acid, lithium-ion, liquid flow and sodium-sulfur batteries, interconnected to medium voltage (MV) or low voltage (LV) distribution networks via bidirectional DC to AC power converters. This document will specify active and reactive power response and grid-connected testing for distributed BESS, as a supplement for IEC TS 62786-1:2023.
This document specifies interface requirements for connection of distributed BESS with the distribution network operating at a nominal frequency of 50 Hz or 60 Hz.

General Information

• Status: Published
• Publication Date: 27-Nov-2023
• ICS: 29.240.01 - Power transmission and distribution networks in general
• Technical Committee: TC 8 - System aspects of electrical energy supply
• Drafting Committee: JWG 10 - TC 8/JWG 10
• Current Stage: PPUB - Publication issued
• Start Date: 17-Nov-2023
• Completion Date: 28-Nov-2023

Standards Content (Sample)

IEC TS 62786-3 ®
Edition 1.0 2023-11
TECHNICAL
SPECIFICATION
colour
inside
Distributed energy resources connection with the grid –
Part 3: Additional requirements for stationary battery energy storage
system
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IEC TS 62786-3 ®
Edition 1.0 2023-11
TECHNICAL
SPECIFICATION
colour
inside
Distributed energy resources connection with the grid –
Part 3: Additional requirements for stationary battery energy storage
system
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.01 ISBN 978-2-8322-7667-9
– 2 – IEC TS 62786-3:2023 © IEC 2023
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions, abbreviated terms and symbols . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms and symbols . 9
3.2.1 Abbreviated terms . 9
3.2.2 Symbols . 9
4 Requirements for distributed BESS . 11
4.1 General . 11
4.2 Connection scheme . 11
4.3 Choice of switchgear . 11
4.3.1 General . 11
4.3.2 Interface switch . 11
4.4 Normal operating range . 11
4.4.1 General . 11
4.4.2 Operating frequency range . 11
4.4.3 Operating voltage range . 12
4.5 Immunity to disturbances . 12
4.5.1 General . 12
4.5.2 Rate of change of frequency (ROCOF) immunity . 12
4.5.3 Under voltage ride through (UVRT) requirements . 12
4.5.4 Over voltage ride through (OVRT) requirements . 12
4.5.5 Rapid phase angle change immunity . 12
4.6 Active power response to frequency deviation . 13
4.6.1 General . 13
4.6.2 Active power response to over frequency . 14
4.6.3 Active power response to underfrequency . 14
4.7 Power response to voltage changes . 15
4.7.1 General . 15
4.7.2 Voltage support by reactive power . 15
4.7.3 Reactive power control modes . 15
4.7.4 Voltage related active power control . 15
4.7.5 Voltage related reactive power response . 16
4.7.6 Additional reactive current requirements on BESS . 16
4.8 EMC and power quality . 16
4.8.1 General . 16
4.8.2 Direct current (DC) injection . 16
4.9 Interface protection . 17
4.9.1 General . 17
4.9.2 Requirements on voltage and frequency protection . 17
4.9.3 Means to detect islanding situation . 17
4.9.4 Digital input to the interface protection . 17
4.10 Connection and starting to generate electrical power . 17
4.10.1 General . 17
4.10.2 Connection of BESS . 17
4.10.3 Auto reclose of distribution lines . 17

4.10.4 Black start capability and intentional islanding control . 17
4.11 Ceasing and reduction of active power on set point. 17
4.12 Remote information exchange . 17
4.12.1 General . 17
4.12.2 Monitoring and control . 18
4.12.3 Communication . 18
5 Conformance tests . 18
Annex A (normative) Operating frequency range . 19
Annex B (normative) Operating voltage range . 20
Annex C (normative) Summary of power thresholds to be defined by individual
countries . 21
Bibliography . 22

Figure 1 – Example of the interconnection interface concept . 8
Figure 2 – Typical power-frequency response curve for BESS charging and discharging

modes under operating frequency range . 13
Figure 3 – Example of reactive power capability range of BESS in per unit at nominal
voltage . 15
Figure 4 – Typical voltage related active power regulation of BESS . 16

Table 1 – Operating frequency requirements of BESS. 11
Table 2 – Operating voltage requirements of BESS with LV distribution network . 12
Table A.1 – Continuous operating frequency range . 19
Table A.2 – Limited operating frequency range . 19
Table A.3 – Limited charging/discharging time . 19
Table B.1 – Continuous operating POC voltage range . 20
Table B.2 – Limited operating voltage range . 20

– 4 – IEC TS 62786-3:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DISTRIBUTED ENERGY RESOURCES CONNECTION WITH THE GRID –

Part 3: Additional requirements for stationary
battery energy storage system
FOREWORD
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