IEC TS 62933-3-3:2022

Electrical energy storage (EES) systems - Part 3-3: Planning and performance assessment of electrical energy storage systems - Additional requirements for energy intensive and backup power applications

IEC TS 62933-3-3:2022 provides requirements, guidelines and references when EES systems are designed, controlled and operated for energy intensive, islanded grid and backup power supply applications. In energy intensive applications, the EES system provides long charge and discharge phases at variable powers to the supported grid or user equipment. In islanded operation, the EES system provides energy to the islanded grid and coordinates other power generation systems in the islanded grid. In backup power supply and emergency support, the EES system provides energy to the internal grid or a set of emergency loads when the main grid power supply is not available.

General Information

• Status: Published
• Publication Date: 03-Nov-2022
• ICS: 13.020.30 - Environmental impact assessment
• Technical Committee: TC 120 - Electrical Energy Storage (EES) systems
• Drafting Committee: WG 3 - TC 120/WG 3
• Current Stage: PPUB - Publication issued
• Start Date: 04-Nov-2022
• Completion Date: 06-Dec-2022

Overview

IEC TS 62933-3-3:2022 - "Electrical energy storage (EES) systems - Part 3-3" provides requirements, guidelines and references for the planning and performance assessment of electrical energy storage systems when used in energy intensive, islanded grid, and backup power / emergency support applications. The technical specification addresses design, control, operation, monitoring, sizing and service‑life considerations specific to long-duration charge/discharge duties, islanded coordination with distributed generation, and backup-power scenarios.

Key topics and technical requirements

• Scope and terminology: normative references, terms, definitions and symbols to ensure consistent planning and assessment.
• Application-specific design: structure and subsystem requirements tailored for peak shaving, load levelling, islanded grids and backup power.
• Grid integration and interconnection: guidance on point-of-connection conditions, grid parameters and technology‑dependent interconnection schemes (see Annex A).
• Operation and control strategies: control modes for variable charge/discharge, coordination with other generation in islanded operation, and emergency switching for backup supply.
• Sizing and planning processes: methods and example processes to determine energy and power sizing, duty cycles, and resulting operational constraints (illustrated with figures and flowcharts).
• Monitoring, communications and interfaces: required monitoring data, communication interfaces and information exchange use cases between EES, power conversion systems and grid/plant controllers (see Annex B for battery-specific monitoring items).
• Maintenance and service life: installation, performance assessment, maintenance strategies and end‑of‑service considerations for different application profiles.
• Performance assessment: metrics and assessment procedures to verify that EES systems meet application requirements over their service life.

Practical applications

IEC TS 62933-3-3:2022 is intended for projects where EES systems are used to:

• Provide long-duration peak shaving and load levelling in energy-intensive facilities.
• Operate as the primary energy source and coordinate distributed resources in islanded microgrids.
• Deliver reliable backup power and emergency support for critical loads, or replace/augment diesel generators.

Who should use this standard

• System designers and integrators planning EES installations for industrial, commercial or microgrid use.
• Asset owners and operators specifying performance, monitoring and maintenance regimes.
• Grid and distribution operators assessing connection conditions and operational limits.
• Consultants, certifiers and regulators reviewing compliance, safety and performance claims.
• Manufacturers of batteries, BMS, PCS and energy management systems who need to align products with planning and operational requirements.

Related standards

Refer to other parts of the IEC TS 62933 series and IEC standards covering grid interconnection, battery safety and power conversion systems for complementary requirements and detailed technology standards.

Standards Content (Sample)

IEC TS 62933-3-3 ®
Edition 1.0 2022-11
TECHNICAL
SPECIFICATION
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inside
Electrical energy storage (EES) systems –
Part 3-3: Planning and performance assessment of electrical energy storage
systems – Additional requirements for energy intensive and backup power
applications
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IEC TS 62933-3-3 ®
Edition 1.0 2022-11
TECHNICAL
SPECIFICATION
colour
inside
Electrical energy storage (EES) systems –

Part 3-3: Planning and performance assessment of electrical energy storage

systems – Additional requirements for energy intensive and backup power

applications
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.020.30 ISBN 978-2-8322-6007-4

– 2 – IEC TS 62933-3-3:2022  IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, abbreviated terms and symbols . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms and symbols . 10
3.2.1 Abbreviated terms . 10
3.2.2 Symbols . 11
4 General planning and performance assessment considerations for EES systems . 11
5 Peak shaving and load levelling . 11
5.1 Application of EES system . 11
5.1.1 Functional purpose . 11
5.1.2 Applications related requirements . 11
5.2 Conditions and requirements for connection to the grid . 11
5.3 Design of the EES systems . 12
5.3.1 Structure of the EES systems . 12
5.3.2 Subsystem specification and requirements . 12
5.3.3 Grid integration of the EES systems . 12
5.3.4 Operation and control . 12
5.3.5 Monitoring . 15
5.3.6 Maintenance . 15
5.3.7 Communication interface . 15
5.4 Sizing and resulting parameters of the EES system . 16
5.4.1 Sizing . 16
5.4.2 Characteristics and restrictions of the EES system . 17
5.5 Service life of the EES system . 17
5.5.1 Installation . 17
5.5.2 Performance assessment . 17
5.5.3 Operation and control . 18
5.5.4 Monitoring . 21
5.5.5 Maintenance . 21
6 Islanded grid application . 21
6.1 Application of the EES system . 21
6.1.1 Functional purpose . 21
6.1.2 Applications related requirements . 21
6.2 Conditions and requirements for connection to the grid . 21
6.2.1 Grid parameters at the intended POC . 21
6.2.2 Service conditions . 21
6.2.3 Requirements and restrictions of the grid or system operator . 21
6.2.4 Standards and local regulations . 21
6.3 Design of the EES system . 22
6.3.1 Structure of the EES system . 22
6.3.2 Subsystem specifications . 23
6.3.3 Grid integration of the EES system . 23
6.3.4 Operation and control . 23

6.3.5 Monitoring . 24
6.3.6 Maintenance . 24
6.3.7 Communication interface . 24
6.4 Sizing and resulting parameters of the EES system . 24
6.4.1 Sizing . 24
6.4.2 Characteristics and restrictions of the EES system . 26
6.5 Service life of the EES system . 26
6.5.1 Installation . 26
6.5.2 Performance assessment . 26
6.5.3 Operation and control . 26
6.5.4 Monitoring . 27
6.5.5 Maintenance . 27
7 Backup power supply and emergency support . 28
7.1 Applications of the EES system. 28
7.1.1 Functional purpose of the EES system. 28
7.1.2 Applications related requirements . 28
7.2 Conditions and requirements for connection to the grid . 28
7.3 Design of the EES system . 28
7.3.1 Structure of the EES systems . 28
7.3.2 Subsystem specifications and requirements . 28
7.3.3 Grid integration of the EES system . 28
7.3.4 Operation and control . 32
7.3.5 Monitoring . 32
7.3.6 Maintenance . 32
7.3.7 Communication interface . 32
7.4 Sizing and resulting parameters of the EES system . 33
7.4.1 Sizing . 33
7.4.2 Characteristics and restrictions of the EES system . 34
7.5 Service life of the EES system . 34
7.5.1 Installation . 34
7.5.2 Performance assessment . 35
7.5.3 Operation and control . 35
7.5.4 Monitoring . 39
7.5.5 Maintenance . 39
Annex A (informative) Technology dependent requirements for grid interconnection
scheme . 40
Annex B (informative) Specific requirements for battery-based EES systems . 44
Bibliography . 46

Figure 1 – An example of peak shaving and fluctuation reduction of consumption
consisting of charge and discharge events . 13
Figure 2 – One charge and one discharge duty cycle for peak shaving application . 14
Figure 3 – Two charges and two discharges duty cycle for peak shaving application. 15
Figure 4 – Use case for information exchange between grid and EES system . 16
Figure 5 – Process to determine the sizing and planning of the EES system applied in
peak shaving and fluctuation reduction of consumption applications . 17
Figure 6 – Sequence of charging events in peak shaving application . 19
Figure 7 – Sequence of discharging events in peak shaving application . 20

– 4 – IEC TS 62933-3-3:2022  IEC 2022
Figure 8 – Example configuration for applying an EES system to an islanded grid
containing distributed energy resources . 23
Figure 9 – Example process to determine the sizing and planning of EES system

applied in islanded grid application . 25
Figure 10 – Example use case for backup power using a diesel generator . 29
Figure 11 – Simple replacement of diesel generator with EES system for backup power
support . 30
Figure 12 – EES system use case for both backup power and EES’s own functions . 31
Figure 13 – EES system use case for communication with distribution panel . 32
Figure 14 – Example process to determine the sizing and planning of the EES system
applied to the backup power supply and emergency support application . 33
Figure 15 – Example operation flow for backup power support during grid outage . 36
Figure 16 – Example operation flow for backup power support when grid is recovered . 36
Figure 17 – Example of configuration for low voltage connection . 38
Figure 18 – Example of configuration for high voltage connection . 39
Figure A.1 – Grounded Y-Δ (GY-Δ) interconnection between grid and EES system . 40
Figure A.2 – Grounded Y-grounded Y (GY-GY) interconnection between grid and EES

system . 41
Figure A.3 – Δ-grounded Y (Δ-GY) interconnection between grid and EES system . 42
Figure A.4 – Non-transformer direct interconnection between grid and EES system . 43

Table 1 – Operation modes of EES system for peak shaving and fluctuation reduction
of consumption . 12
Table 2 – Conditions for charging/discharging limitation . 21
Table 3 – Example of the operation time for emergency load facilities. 34
Table A.1 – Pros and cons of grounded Y-Δ (GY-Δ) interconnection scheme . 41
Table A.2 – Pros and cons of grounded Y-grounded Y (GY-GY) interconnection
scheme . 42
Table A.3 – Pros and cons of Δ-grounded Y (Δ-GY) interconnection scheme . 43
Table A.4 – Pros and cons of non-transformer direct interconnection scheme . 43
Table B.1 – BMS data monitored by PMS . 45
Table B.2 – PCS data monitored by PMS . 45
Table B.3 – PCS controls sent by PMS . 45

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –

Part 3-3: Planning and performance assessment of electrical energy
storage systems – Additional requirements for energy intensive and
backup power applications
FOREWORD
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC TS 62933-3-3 has been prepared by IEC technical committee 120: Electrical Energy
Storage (EES) Systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
120/262/DTS 120/275/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.

– 6 – IEC TS 62933-3-3:2022  IEC 2022
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts in the IEC 62933 series, published under the general title Electrical energy
storage (EES) systems, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
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INTRODUCTION
Electrical energy storage (EES) systems can provide solutions to multiple energy storage
scenarios. The objective of this document is to provide requirements, guidelines and references
when EES systems are designed, controlled and operated for energy intensive, islanded grid
and backup power supply applications.

– 8 – IEC TS 62933-3-3:2022  IEC 2022
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –

Part 3-3: Planning and performance assessment of electrical energy
storage systems – Additional requirements for energy intensive and
backup power applications
1 Scope
This part of IEC 62933 provides requirements, guidelines and references when EES systems
are designed, controlled and operated for energy intensive, islanded grid and backup power
supply applications. In energy intensive applications, the EES system provides long charge and
discharge phases at variable powers to the supported grid or user equipment. In islanded
operation, the EES system provides energy to the islanded grid and coordinates other power
generation systems in the islanded grid. In backup power supply and emergency support, the
EES system provides energy to the internal grid or a set of emergency loads when the main
grid power supply is not available.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 61850-7-420, Communication networks and systems for power utility automation – Part 7–
420: Basic communication structure – Distributed energy resources and distribution automation
logical nodes
IEC TR 61850-90-9, Communication networks and systems for power utility automation –
Part 90-9: Use of IEC 61850 for Electrical Energy Storage Systems
IEC 62933-1:2018, Electrical energy storage (EES) systems – Part 1: Vocabulary
IEC 62933-2-1, Electrical energy storage (EES) systems – Part 2-1: Unit parameters and testing
methods – General specification
IEC TS 62933-2-2, Electrical energy storage (EES) systems – Part 2-2: Unit parameters and
testing methods – Application and performance testing
IEC TS 62933-3-1:2018, Electrical energy storage (EES) systems – Part 3-1: Planning and
performance assessment of electrical energy storage systems – General specification
IEC TS 62933-3-2:2022, Electrical energy storage (EES) systems – Part 3-2: Planning and
performance assessment of electrical energy storage systems – Additional requirements for
power intensive and renewable energy sources integration related applications
3 Terms, definitions, abbreviated terms and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62933-1 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/;
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
backup power supply
provision of power to all internal loads connected to user side equipment during a specified time
period without relying on an external power source in the event of electrical grid outage
3.1.2
black start capability
capability of the EES system to start the electric power system (IEV 601-01-01) only with
internal energy resources
3.1.3
allowed charging time
time period when an EES system is allowed to charge the accumulation subsystem in the peak
shaving application
3.1.4
allowed discharging time
time period when an EES system is allowed to discharge the accumulation subsystem in the
peak shaving application
3.1.5
duty cycle roundtrip efficiency
energy discharged measured at the primary POC divided by the energy absorbed by the EES
system, as a sum of what is measured at all the POCs (primary and auxiliary), during duty
cycles in a specified operating mode at continuous operating conditions with the same final
state of charge as the initial state of charge
[SOURCE: IEC 62933-1:2018, 4.12.1, modified – the notes have been deleted.]
3.1.6
emergency load
set of devices and equipment that should be operated during electrical grid outage
3.1.7
emergency support
provision of power to emergency loads within a specified time and duration without relying on
an external power source in the event of electrical grid outage
3.1.8
energy intensive application
EES system application generally not very demanding in terms of step response performances
but with long charge and discharge phases at variable powers
[SOURCE: IEC 62933-1:2018, 3.12, modified – the terms “long duration application” and “long
term application” have been deleted and the notes have been deleted.]
3.1.9
fluctuation reduction of consumption
reduction of power oscillation of power consumption at the grid connection point by absorbing
the active power of the grid by EES systems at low power demand phases and by feeding in
additional active power by EES systems at high power demand phases

– 10 – IEC TS 62933-3-3:2022  IEC 2022
3.1.10
islanded grid
part of an electric power system that is electrically disconnected from the remainder of the
interconnected electric power system but remains energized from the local electric power
sources
3.1.11
islanded operation
function to provide power to the islanded grid and to control the coordination with other power
generation systems and the system voltage and frequency
3.1.12
load profile
line graph illustrating the variation in loads over a specific time
3.1.13
peak shaving
limitation of the power consumption from the power grid to a maximum value by providing the
power exceeding the maximum value from other active power sources
3.1.14
rated AC current
AC current that the EES system can provide to the grid continuously and can accept from the
grid continuously without exceeding the maximum operating temperature of the EES system
3.1.15
self-discharge
phenomenon by which the EES system accumulation subsystem loses energy in other ways
than by discharge through the primary POC
[SOURCE: IEC 62933-1:2018, 4.12.7, modified – the note has been deleted.]
3.2 Abbreviated terms and symbols
3.2.1 Abbreviated terms
ACB air circuit breaker
ATS automatic transfer switch
BMS battery management system
CVCF constant voltage constant frequency
DER distributed energy resources
DNP distributed network protocol
EES electrical energy storage
EMS energy management system
GHG greenhouse gas
HVAC heating, ventilation, and air conditioning
PCS power conversion system
PMS power management system
POC point of connection
PV photovoltaics
SOC state of charge
SOH state of health
TR transformer
UVRT under voltage ride through
VT voltage transformer
3.2.2 Symbols
f frequency
P active power
Q reactive power
S apparent power
Y star configuration
Δ delta configuration
4 General planning and performance assessment considerations for EES
systems
Clause 4 presents the general and common requirements for various applications of EES
systems. IEC TS 62933-3-1 shall be applied. Clause 4 of IEC TS 62933-3-2:2022 is also
applicable.
5 Peak shaving and load levelling
5.1 Application of EES system
5.1.1 Functional purpose
The EES system performs a shift, in time, of available energy to achieve more uniformity in
power generation and consumption pattern. With this activity, peaks in power consumption and
associated power generation demand are smoothed. This results in a reduction in behind-the-
meter demand charges by an appropriate timing of the activation of power generation or power
storage assets.
NOTE This document covers peak shaving and load levelling application from the perspective of behind the meter.
5.1.2 Application related requirements
5.1.2.1 General
In the peak shaving and fluctuation reduction of consumption applications, in addition to the
application independent requirements listed in 4.1.2 of IEC TS 62933-3-2:2022, the following
application specific requirements shall be considered.
5.1.2.2 Specific requirements
In energy fluctuation reduction applications, the following application specific recommendations
should be considered:
• load profile;
• charging-discharging time;
• rated AC current;
• duty cycle efficiency.
5.2 Conditions and requirements for connection to the grid
Subclause 4.2 of IEC TS 62933-3-2:2022 is applicable.

– 12 – IEC TS 62933-3-3:2022  IEC 2022
5.3 Design of the EES systems
5.3.1 Structure of the EES systems
The EES system structure and components defined in 4.3.2 of IEC TS 62933-3-2:2022 shall
also be applied to the peak shaving and fluctuation reduction of consumption applications.
5.3.2 Subsystem specifications and requirements
Subclause 4.3.3 of IEC TS 62933-3-2:2022 is applicable. Further, additional technology
dependent requirements are defined in Annex B.
5.3.3 Grid integration of the EES systems
Subclause 4.3.4 of IEC TS 62933-3-2:2022 is applicable. Further, additional technology
dependent requirements are defined in Annex A.
5.3.4 Operation and control
5.3.4.1 Overview
Subclause 4.3.5 of IEC TS 62933-3-2:2022 is applicable. In addition, the following
recommendations should be considered.
5.3.4.2 General
There are three types of operation periods of the EES system for peak shaving and fluctuation
reduction of consumption applications, namely peak period, idle period, and off-peak period.
The EES system operation modes for each operation period are listed in Table 1.
Table 1 – Operation modes of EES system for peak shaving
and fluctuation reduction of consumption
Operation mode Discharge Standby Charge
(type of period) (peak period) (idle period) (off-peak period)
Try not to take power Minimize the interaction Try not to discharge to
Scheduling principle
from the grid. with the grid. the grid.
Avoid charging and
The EES system EES system charges from
Approach discharging from the grid
discharges to the grid. the grid.
to EES system.
Restore EES system to a
predefined SOC.
Reduce the pressure on
Maintain stable operation
Absorb excess energy
Purpose the grid during peak
of the grid.
from the grid and
period.
increase energy
efficiency.
The EES system for peak shaving and fluctuation reduction of consumption can be operated to
provide one or multiple charge and discharge sequences or cycles per day. Figure 1 shows the
operation modes and effect of the EES system using "one charging and one discharging" as an
example. In Figure 1, the dashed line indicates the target input power from the grid and the
solid line indicates the load over time. When the load level is below the target input power
during the off-peak period, the EES system charges from the grid. When the load level exceeds
the target input power during the peak period, the EES system performs a discharging operation.

Figure 1 – Example of peak shaving and fluctuation reduction
of consumption consisting of charge and discharge events
5.3.4.3 Operation modes of control subsystem
The operation modes of the EES system are charge, discharge, and standby. The operation
modes over time are determined by a duty cycle. When determining the duty cycle, the following
recommendations should be considered.
• The EES system should be charged at the off-peak period (usually at night), and the EES
system should be put into standby mode after the accumulation subsystem is fully charged.
• The EES system can be operated in various duty cycles, such as "one charge and one
discharge", "one charge and two discharges", "two charges and two discharges", and
"multiple charges and multiple discharges". The specific charge-discharge power and time
of the EES system are set by the operating mechanism and the scheduling mechanism.
• The scheduling mechanism manages the EES system at peak period to discharge, and the
power response time of the EES system does not exceed a predetermined time.
• The EES system can automatically receive the dispatching curve issued by the grid system
and operate according to the power generation plan curve. The deviation between the actual
output curve and the scheduling command curve needs to be determined before this
operation.
In the case that the power curve is not formulated by the grid dispatch organization, the EES
system should distribute the charge-discharge power and time according to the loads and the
internal constraints of the EES system.
Subclause 5.3.4.3 presents one charge and one discharge duty cycle, and two charges and two
discharges duty cycle as examples. Other duty cycles may be used depending on the situation,
and are presented in IEC 62933-2-1 and IEC TS 62933-2-2.
a) One charge and one discharge duty cycle
Figure 2 displays the example of duty cycles for a midnight-to-midnight day with an
afternoon peak. Each duty cycle in the figure consists of a total of 12 h duration for charging.
The required discharge duration and a standby duration after charge and discharge bring
the total duration for each of the A, B, and C duty cycles to one 24 h cycle. The peak period
for discharging starts at 13:00 for duty cycle A, 14:00 for duty cycle B, and 15:00 for duty
cycle C, respectively. Prior to the peak period, the EES system should be charged to
maximum SOC. When operating the A, B, and C cycles, the EES system should be returned
to the same SOC as the SOC at the start of the duty cycle, which in this case is the maximum
SOC. Thus, each duty cycle A, B, and C consists of a discharge followed by standby, charge,
and standby to bring the EES system to the initial SOC.
• Off-peak period (charge mode): During the off-peak period, the EES system is charged
generally with a sequential constant power–constant voltage charging profile to bring

– 14 – IEC TS 62933-3-3:2022  IEC 2022
the accumulation subsystem of the EES system to its upper SOC limit. The exact profile
and associated conditions are specified by the manufacturer of the battery system.
• Peak period (discharge mode): During the peak period, the EES system is discharged
at constant power until the minimum SOC level for the discharge power is reached. The
minimum SOC level is specified by the EES system operator.
• Idle period (standby mode): During the idle period, the EES system does not perform a
charge or discharge operation to an external load of EES system. When the EES system
does not have an auxiliary POC, the lower SOC limit might not be maintained and the
operation of any internal support loads for the EES system, such as, but not limited to,
heating, ventilation, and air-conditioning systems, continues to operate as required in
accordance with the EES system manufacturer’s specifications and operating
instructions. Discharging of the EES system that does not serve a load external to the
EES system is permitted during the idle period.

a) Peak shaving duty cycle A, 6 h discharge

b) Peak shaving duty cycle B, 4 h discharge

c) Peak shaving duty cycle C, 2 h discharge
[Source: IEC TS 62933-2-2.]
Figure 2 – One charge and one discharge duty cycle for peak shaving application
b) Two charges and two discharges duty cycle
Figure 3 displays an example of duty cycle for a midnight-to-midnight day with a morning
peak and an evening peak. The duty cycle has a total of 13 h duration for charging and a
total of 8 h duration for discharging. The required off-peak periods are 00:00 ~ 8:00 and
12:00 ~ 17:00. The required peak periods are 8:00 to 12:00 and 17:00 to 21:00. The required
peak period and required off-peak period are set by the EES system operator according to
the investigated load profiles. There is an idle period between 21:00 and 00:00 that brings

the total duration for each duty cycle to one 24 h period. The EES system starts with a
charge at 00:00 for a duty cycle. The EES system will be charged and discharged two times
a day in an optimal capacity configuration, which can effectively achieve the function of peak
shaving and fluctuation reduction of consumption, and economic efficiency.
When applying the duty cycle shown in Figure 3, the duty cycle might not be adequate
depending on the type of accumulation subsystem. For example, in a battery-based
accumulation subsystem, a two-cycles per day with charge, discharge, charge and
discharge with no rest time can decrease battery life. Depending on the cell/module
temperature, it could be necessary to wait some time until the temperature decreases below
a safe level between each consecutive phase of charge or discharge.

[Source: IEC TS 62933-2-2]
Figure 3 – Two charges and two discharges duty cycle
for peak shaving application
5.3.5 Monitoring
Subclause 4.3.6 of IEC TS 62933-3-2:2022 is applicable.
5.3.6 Maintenance
Subclause 4.3.7 of IEC TS 62933-3-2:2022 is applicable.
5.3.7 Communication interface
Subclause 4.3.8 of IEC TS 62933-3-2:2022 is applicable. In addition, the following
recommendations should be considered. Further additional technology dependent requirements
are defined in Annex B.
An EES system interacting, as distributed energy source, with a transmission, distribution or
islanded grid, should exchange relevant information with their management entities as defined
in IEC 61850-7-420 and IEC TR 61850-90-9. The operational procedures for information
exchange shown in Figure 4 are presented in IEC TR 61850-90-9.

– 16 – IEC TS 62933-3-3:2022  IEC 2022

[Source: IEC TR 61850-90-9]
Figure 4 – Use case for information exchange between grid and EES system
5.4 Sizing and resulting parameters of the EES system
5.4.1 Sizing
5.4.1.1 General
Subclause 4.4.2 of IEC TS 62933-3-2:2022 is applicable. In addition, the following
recommendations should be considered.
5.4.1.2 Sizing and planning process of the EES system
The general sizing and planning process of the EES system applied in the peak shaving and
fluctuation reduction of consumption applications is depicted in Figure 5.

Figure 5 – Process to determine the sizing and planning of the EES system applied in
peak shaving and fluctuation reduction of consumption applications
5.4.1.3 Requirements for sizing and planning
When performing the sizing and planning process of EES system, the following
recommendations should be met:
• the effect of different types of energy storage technologies on peak shaving/fluctuation
reduction of consumption;
• the charge and discharge power, and energy storage capacity of the EES system;
• different control strategies;
• the life of the accumulation subsystem, the charge-discharge characteristics and the optimal
charge-discharge cycles.
The sizing and planning of the EES system shall be set according to the power and the operation
mode of the accumulation subsystem. The initial accumulation subsystem size can be
configured as 5 % to 20 % of the transformer capacity interconnecting the EES system and grid,
and subsequently determined after calculation.
5.4.2 Characteristics and restrictions of the EES system
Subclause 4.4.3 of IEC TS 62933-3-2:2022 is applicable.
5.5 Service life of the EES system
5.5.1 Installation
Subclause 4.5.2 of IEC TS 62933-3-2:2022 is applicable.
5.5.2 Performance assessment
Subclause 4.5.3 of IEC TS 62933-3-2:2022 is applicable.

– 18 – IEC TS 62933-3-3:2022  IEC 2022
5.5.3 Operation and control
5.5.3.1 General
Subclause 4.5.4 of IEC TS 62933-3-2:2022 is applicable. In addition, the following
recommendations should be considered. Further additional technology dependent requirements
are defined in Annex B.
5.5.3.2 Control process of the EES system
The EMS determines the working state of the EES system by predicting the load demand (MW)
and the real-time power value (MW) of the power grid, and calculates the charge-discharge
power of the EES system under the different states defined in Table 1. The example control
process of the EES system for charging in the peak shaving and fluctuation reduction of
consumption is shown in Figure 6. Additional descriptions for the numbered processes in
Figure 6 are as follows.
1) During the system status check in (1), the functions of the distribution panel, power
conversion subsystem, accumulation subsystem, air conditioning and ventilation system,
fire extinguishing system, and emergency stop function should be checked.
2) The allowed charging time period in (2) is determined by checking the allowed charging
period, configured charging time, or off-peak period.
3) The configured threshold value for the charging state in (4) depends on the type of
accumulation subsystem. For example, a SOC of 95 % can be the threshold in the bat
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