Electrical energy storage (EES) systems - Part 2-200: Unit parameters and testing methods - Case study of electrical energy storage (EES) systems located in EV charging station with PV

IEC TR 62933-2-200:2021(E) presents a case study of electrical energy storage (EES) systems located in electric vehicle (EV) charging stations with photovoltaic (PV) power generation (PV-EES-EV charging stations) with a voltage level of 20 kV and below. EES systems are highlighted in this document because they are a desired option to make the charging stations (especially the high-power fast charging stations) grid-friendly, improve the self-consumption of clean energy generation, and increase the revenue of stations. In this application, EES systems show excellent performance by running in a variety of available operating modes, such as peak shaving, power smoothing, load tracing, time-of-use (TOU) price arbitrage, and ancillary services. The general duty cycle is recommended based on the summary of the operation characteristics of the EES systems.

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Status
Published
Publication Date
02-Sep-2021
Current Stage
PPUB - Publication issued
Completion Date
03-Sep-2021
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IEC TR 62933-2-200:2021 - Electrical energy storage (EES) systems - Part 2-200: Unit parameters and testing methods - Case study of electrical energy storage (EES) systems located in EV charging station with PV
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IEC TR 62933-2-200
Edition 1.0 2021-09
TECHNICAL
REPORT
colour
inside
Electrical energy storage (EES) systems –
Part 2-200: Unit parameters and testing methods – Case study of electrical
energy storage (EES) systems located in EV charging station with PV
IEC TR 62933-2-200:2021-09(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TR 62933-2-200
Edition 1.0 2021-09
TECHNICAL
REPORT
colour
inside
Electrical energy storage (EES) systems –
Part 2-200: Unit parameters and testing methods – Case study of electrical
energy storage (EES) systems located in EV charging station with PV
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.020.30; 27.160; 43.120 ISBN 978-2-8322-1021-0

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TR 62933-2-200:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 5

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms, definitions and abbreviated terms ........................................................................ 7

3.1 Terms and definitions .............................................................................................. 7

3.2 Abbreviated terms ................................................................................................... 7

4 Overview of EES systems located in EV charging stations with PV power

generation ....................................................................................................................... 8

4.1 General ................................................................................................................... 8

4.2 Application scenarios .............................................................................................. 8

4.3 System communication architecture ........................................................................ 9

4.4 Duty cycle analysis ............................................................................................... 10

5 Project of commercial PV-EES-EV charging station based on common DC bus ............. 11

5.1 Case project overview ........................................................................................... 11

5.2 System operation and control ................................................................................ 12

5.2.1 Operation data analysis ................................................................................. 12

5.2.2 Operation mode analysis ............................................................................... 13

5.3 Summary .............................................................................................................. 15

6 Project of commercial PV-EES-EV charging station based on common AC bus ............. 17

6.1 Case project overview ........................................................................................... 17

6.2 System operation and control ................................................................................ 18

6.2.1 Operation data analysis ................................................................................. 18

6.2.2 Operation mode analysis ............................................................................... 19

6.3 Summary .............................................................................................................. 21

7 Project of business PV-EES-EV charging station based on common DC bus ................. 23

7.1 Case project overview ........................................................................................... 23

7.2 System operation and control ................................................................................ 24

7.2.1 Operation data analysis ................................................................................. 24

7.2.2 Operation mode analysis ............................................................................... 25

7.3 Summary .............................................................................................................. 27

8 Project of business PV-EES-EV charging station based on common AC bus ................. 29

8.1 Case project overview ........................................................................................... 29

8.2 System operation and control ................................................................................ 29

8.2.1 Operation data analysis ................................................................................. 29

8.2.2 Operation mode analysis ............................................................................... 30

8.3 Summary .............................................................................................................. 33

9 Recommendation for operation modes of EES systems located in EV charging

station with PV panels ................................................................................................... 34

Annex A (informative) Duty cycles of the EES systems located in EV charging station

with PV ................................................................................................................................. 36

A.1 General ................................................................................................................. 36

A.2 Project of commercial PV-EES-EV charging station based on common DC

bus ....................................................................................................................... 36

A.3 Project of commercial PV-EES-EV charging station based on common AC

bus ....................................................................................................................... 38

A.4 Project of business PV-EES-EV charging station based on common DC bus ........ 45

Bibliography .......................................................................................................................... 47

---------------------- Page: 4 ----------------------
IEC TR 62933-2-200:2021 © IEC 2021 – 3 –
Figure 1 – Example of communication system architecture of PV-EES-EV charging

station ........................................................................................................................... 10

Figure 2 – System structure of case commercial PV-EES-EV charging station based on

common DC bus ................................................................................................................... 11

Figure 3 – EV load and PV power for the case of a commercial charging station based

on common DC bus .............................................................................................................. 12

Figure 4 – TOU and charging service prices for the case of a commercial charging

station based on common DC bus ......................................................................................... 12

Figure 5 – Operating power in low- and medium-price periods in the case of a

commercial charging station based on common DC bus ........................................................ 14

Figure 6 – Operating power in high-price periods in the case of commercial charging

station based on common DC bus ......................................................................................... 15

Figure 7 – EES system duty cycle in the case of a commercial charging station based

on common DC bus .............................................................................................................. 15

Figure 8 – Daily electricity flow for the case of a commercial charging station based on

common DC bus ................................................................................................................... 17

Figure 9 – System structure for the case of a commercial PV-EES-EV charging station

based on common AC bus .................................................................................................... 18

Figure 10 – EV load and PV power for the case of a commercial charging station based

on common AC bus ............................................................................................................... 19

Figure 11 – Operating power in power smoothing mode for the case of a commercial

charging station based on common AC bus........................................................................... 19

Figure 12 – Operating power in peak shaving mode for the case of a commercial

charging station based on common AC bus........................................................................... 20

Figure 13 – Operating power in the TOU price arbitrage mode for the case of a

commercial charging station based on common AC bus ........................................................ 21

Figure 14 – EES duty cycle for the case of a commercial charging station based on

common AC bus ................................................................................................................... 22

Figure 15 – Daily electricity flow of for the case of a commercial charging station based

on common AC bus ............................................................................................................... 22

Figure 16 – System structure for the case of a business PV-EES-EV charging station

based on common DC bus .................................................................................................... 23

Figure 17 – PV power, EV load and output power for the case of a business charging

station based on common DC bus ......................................................................................... 24

Figure 18 – TOU and charging service prices for the case of a business charging

station based on common DC bus ......................................................................................... 24

Figure 19 – Operating power in equivalent load tracing mode for the case of a

business charging station based on common DC bus ............................................................ 25

Figure 20 – Operating power in TOU price arbitrage mode for the case of a business

charging station based on common DC bus .......................................................................... 26

Figure 21 – Operating power in demand response mode for the case of a business

charging station based on common DC bus .......................................................................... 27

Figure 22 – Operating power involved in TOU arbitrage and demand response for the

case of a business charging station based on common DC bus ............................................ 27

Figure 23 – EES duty cycle for the case of a business charging station based on

common DC bus ................................................................................................................... 28

Figure 24 – Daily electricity flow for the case of a business charging station based on

common DC bus ................................................................................................................... 28

Figure 25 – System structure for the case of a business PV-EES-EV charging station

based on common AC bus .................................................................................................... 29

---------------------- Page: 5 ----------------------
– 4 – IEC TR 62933-2-200:2021 © IEC 2021

Figure 26 – EV load and PV power for the case of a business charging station based

on common AC bus ............................................................................................................... 30

Figure 27 – Simulation results for operation strategy 1 for the case of a business

charging station based on common AC bus........................................................................... 31

Figure 28 – Simulation results for operation strategy 2 for the case of a business

charging station based on common AC bus........................................................................... 31

Figure 29 – Simulation results for operation strategy 3 for the case of a business

charging station based on common AC bus........................................................................... 33

Figure 30 – Three operation strategies and resultant operation modes of the EES

system for the case of a business charging station based on common AC bus ...................... 33

Table 1 – Time division of EES system’s operation modes in the case of a commercial

charging station based on common DC bus .......................................................................... 16

Table 2 – Time division of the EES system’s operation modes for the case of a

commercial charging station based on common AC bus ........................................................ 21

Table 3 – Time division of EES operation modes for the case of a business charging

station based on common AC bus ......................................................................................... 34

Table 4 – Recommended operation modes of the EES system in various installation

scenarios of a PV-EES-EV charging station .......................................................................... 35

Table A.1 – Charging-discharging power of EES system for the case of a commercial

charging station based on common DC bus (per-unit value) .................................................. 36

Table A.2 – Charging-discharging power of EES system for the case of a commercial

charging station based on common AC bus (per-unit value) .................................................. 38

Table A.3 – Charging-discharging power of EES system for the case of a business

charging station based on common DC (per-unit value) ........................................................ 45

---------------------- Page: 6 ----------------------
IEC TR 62933-2-200:2021 © IEC 2021 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –
Part 2-200: Unit parameters and testing methods –
Case study of electrical energy storage (EES) systems
located in EV charging station with PV
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international

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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

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interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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6) All users should ensure that they have the latest edition of this publication.

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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent

rights. IEC shall not be held responsible for identifying any or all such patent rights.

IEC 62933-2-200 has been prepared by IEC technical committee TC 120: Electrical Energy

Storage (EES) Systems. It is a Technical Report.
The text of this Technical Report is based on the following documents:
Draft Report on voting
120/231/DTR 120/238/RVDTR

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 Report is English.
---------------------- Page: 7 ----------------------
– 6 – IEC TR 62933-2-200:2021 © IEC 2021

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

contains colours which are considered to be useful for the correct understanding of its

contents. Users should therefore print this document using a colour printer.
---------------------- Page: 8 ----------------------
IEC TR 62933-2-200:2021 © IEC 2021 – 7 –
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –
Part 2-200: Unit parameters and testing methods –
Case study of electrical energy storage (EES) systems
located in EV charging station with PV
1 Scope

This part of IEC 62933, which is a Technical Report, presents a case study of electrical energy

storage (EES) systems located in electric vehicle (EV) charging stations with photovoltaic (PV)

power generation (PV-EES-EV charging stations) with a voltage level of 20 kV and below. EES

systems are highlighted in this document because they are a desired option to make the

charging stations (especially the high-power fast charging stations) grid-friendly, improve the

self-consumption of clean energy generation, and increase the revenue of stations. In this

application, EES systems show excellent performance by running in a variety of available

operating modes, such as peak shaving, power smoothing, load tracing, time-of-use (TOU) price

arbitrage, and ancillary services. The general duty cycle is recommended based on the

summary of the operation characteristics of the EES systems.
This document includes the following elements:
– overview of general PV-EES-EV charging stations;
– operational analysis of EES systems in typical project cases;
– summary and recommendation of EES systems’ operation modes.
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 62933-1, Electrical energy storage (EES) systems – Part 1: Vocabulary
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 62933-1 apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.2 Abbreviated terms
AC Alternating current
BAMS Battery array management system
BCMU Battery cluster measurement unit
BMU Battery measurement unit
---------------------- Page: 9 ----------------------
– 8 – IEC TR 62933-2-200:2021 © IEC 2021
CAN Controller area network
DC Direct current
EES Electrical energy storage
EMS Energy management system
EV Electric vehicle
EVSE Electric vehicle supply equipment
PCS Power conversion system
POC Point of connection
PV Photovoltaic
SOC State of charge
TOU Time-of-use
V2G Vehicle-to-grid
4 Overview of EES systems located in EV charging stations with PV power
generation
4.1 General

The growing problems of climate change and environmental degradation on a global scale are

the great challenges faced by people all over the world. Electric vehicles (EVs), which help

reduce dependence on fossil fuels, are the key to advancing energy transition in the

transportation sector. The convenience of charging has always been an important factor that

affects whether consumers consider electric vehicles as an option. In recent years, EV charging

infrastructures, especially the commercial charging stations and the business charging stations,

have achieved rapid growth.

The integration of renewable power generation in the charging stations is conducive to further

improving the use of clean energy while reducing the energy cost of the charging stations.

Limited by the size of the site, PV power generation is often the primary choice for the charging

stations. PV panels can be deployed on the roof of the station or integrated on the top of the

charging infrastructure according to local conditions, which show significant advantages over

wind turbines. However, both PV power and EV charging load are highly uncertain, and the

charging demand of EV users during peak hours sometimes has a huge impact on the stable

operation of the external power grid. EES systems can smooth the charging load of EV users

and promote the local consumption of PV power generation. As for the operation of the charging

station, EES systems can delay the expansion of the transformer at the charging station due to

the rapidly increasing load, achieve peak-valley arbitrage according to TOU prices, and even

assist the charging station to participate in ancillary service of the power grid.

The integration of PV and EES systems is the development trend of the EV charging stations.

Many countries in the world, such as China, the United States, Germany, the United Kingdom,

and Australia, have deployed the projects of EV charging stations integrated with PV and EES

systems.
4.2 Application scenarios

Some PV-EES-EV charging stations are designed to operate off-grid, where the PV system

provides the initial energy and the EES system serves as the storage place for electricity and

timely power EVs. The entire station does not exchange energy with the external grid. At a

charging station that operates in this mode, the capacity of EES systems is the key parameter

that directly determines how many EVs can continue to serve.

Compared with the off-grid ones, the more common operation modes of charging stations are

based on grid-connected operation. In this case, the charging needs of EV owners are always

met even if the installed capacity of the EES system and PV is not sufficient. These kinds of

---------------------- Page: 10 ----------------------
IEC TR 62933-2-200:2021 © IEC 2021 – 9 –

charging facilities are widely deployed in residents’ homes, parking lots, highway service areas

and other places with high traffic flow.

In the grid-connected charging stations, EES systems can operate in a variety of modes, such

as load tracing, peak shaving, power smoothing, TOU price arbitrage, and ancillary service,

rather than simply balancing PV generation and charging load as in off-grid settings.

After investigating a large number of charging stations around the world, four typical application

scenarios for the grid-connected PV-EES-EV charging stations from the perspective of electrical

structure were found, namely commercial charging stations with common direct current (DC)

bus, commercial charging stations with common alternating current (AC) bus, business charging

stations with common DC bus, and business charging stations with common AC bus.

The main purpose of commercial charging stations is to provide charging services for general

EV users and obtain economic revenues. In general, the commercial charging station is an

independent interest subject and can be seen as a general load from the grid point of view due

to the forbidden power feedback to the external grid in most cases. In this document, two

practical cases are discussed in Clause 5 and Clause 6, respectively. In Clause 5, a DC

common bus based PV-EES-EV charging station is introduced. The EES system in this station

plays the role of load tracing and TOU price arbitrage. Alternatively, the PV-EES-EV charging

station in Clause 6 is an AC common bus based station, and the EES system of this station

mainly operates in power smoothing, peak shaving and TOU price arbitrage mode.

Business charging stations generally refer to charging stations built alongside commercial malls,

office buildings, communities, campuses, which can not only provide services for EVs, but also

power the surrounding load. In Clause 7, a common DC bus based PV-EES-EV charging station

is analysed, where the EES system plays a comprehensive role in load tracing, TOU price

arbitrage, and demand response. The entire charging station also undertakes the task of

supplying power to a nearby shopping mall in the price peak time periods
...

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