GB/T 34120-2023Technical requirements for power conversion system of electrochemical energy storage system (English PDF)

Foreword

This document was issued on 28 December 2023 by the State Administration for Market Regulation; Standardization Administration of the PRC and takes effect on 1 July 2024.

It is a GB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

1 Scope

GB/T 34120-2023 specifies the converter that stands between a storage battery and the grid. The battery holds the energy, but the power conversion system decides what the installation can actually do: it converts between DC and AC in both directions, and it is what responds when the grid frequency moves, what rides through a voltage dip instead of disconnecting, and what holds the battery within the operating window that determines its life. As storage has grown from a niche to a substantial share of new grid connections, its behaviour during disturbances has stopped being the operator's private business — a fleet of converters that all disconnect at the same threshold turns a local fault into a system event. This document specifies the technical requirements for the power conversion system of an electrochemical energy storage system, including functional requirements such as start-up and shutdown and power control, together with the performance, protection and grid interaction requirements and the corresponding tests. Under CCS F19, it is written for converter manufacturers, for storage system integrators and project developers, and for the grid operators who set connection conditions and the laboratories that verify compliance with them.

This document specifies the technical requirements for power conversion system of

electrochemical energy storage system (hereinafter referred to as “power conversion

system”), including functional requirements such as start-up and shutdown, power

control, grid-connected and grid-disconnected switching, alarm and protection,

insulation resistance detection, communication, operation information monitoring,

statistics, data display and storage; the performance requirements such as electrical

performance and safety performance; and the requirements for classification and coding,

normal operating conditions, appearance and protection grade, electromagnetic

compatibility, auxiliary systems, inspection rules, marking, packaging, transportation

and storage, etc.

This document is applicable to the design, manufacture, testing, inspection, operation,

maintenance and repair of power conversion systems using electrochemical cells as the

energy storage medium, with an AC terminal voltage of 35 kV and below.

2 Normative references

The following referenced documents are indispensable for the application 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.

GB/T 191, Packaging - Pictorial marking for handling of goods

GB/T 4208, Degrees of protection provide by enclosure (IP code)

GB/T 4798.2, Classification of environmental conditions - Classification of groups

of environmental parameters and their severities - Part 2.Transportation and

handling

GB/T 12325, Power quality - Deviation of supply voltage

GB/T 12326, Power quality - Voltage fluctuation and flicker

GB/T 13384, General specifications for packing of mechanical and electrical

product

GB/T 14549, Quality of electric energy supply - Harmonics in public supply

network

GB/T 15543, Power quality - Three-phase voltage

GB/T 15945, Power quality - Frequency deviation for power system

GB/T 17626.2, Electromagnetic compatibility - Testing and measurement

techniques－Electrostatic discharge immunity test

GB/T 17626.3, Electromagnetic compatibility - Testing and measurement

techniques - Part 3.Radiated, radio-frequency, electromagnetic field immunity test

GB/T 17626.4, Electromagnetic compatibility － Testing and measurement

techniques - Electrical fast transient/burst immunity test

GB/T 17626.5, Electromagnetic compatibility - Testing and measurement

techniques - Surge immunity test

GB/T 17626.6, Electromagnetic compatibility - Testing and measurement

techniques - Immunity to conducted disturbances, induced by radio-frequency

fields

GB/T 17626.8, Electromagnetic compatibility (EMC) - Part 4-8.Testing and

measurement techniques - Power frequency magnetic field immunity test

GB/T 17799.2, Electromagnetic compatibility - Generic standards - Part 2.

Immunity standard for industrial environments

GB/T 20626.1, Specific environmental condition - Electric and electronic products

for plateau - Part 1.General technical requirements

GB/T 24337, Power quality - Interharmonics in public supply network

GB/T 34133, Testing code for power conversion system of energy storage system

DL/T 860 (all parts), Communication networks and systems for power utility

automation

DL/T 2528, General terminology of electrical energy storage

3 Terms and definitions

For the purposes of this document, terms and definitions given in DL/T 2528, as well

as the following, applies to this document.

3.1

The capability of the power conversion system to continuously operate without being

disconnected from the grid within the specified voltage rise range and time interval

when the AC terminal voltage of the power conversion system increases due to power

system accidents or disturbances.

3.8

primary frequency control

The control function in which the power conversion system automatically adjusts active

power in response to the frequency deviation of the power system when the power

system frequency deviates from the target frequency.

[Source. GB/T 40595-2021, 3.1, modified]

3.9

inertia response

The control function in which the power conversion system adjusts active power in

response to the rate of change of power system frequency when the power system

frequency changes rapidly.

3.10

touch current

The current flowing through the body of a person or livestock when the person or

livestock touches one or more accessible parts of an electrical installation or electrical

equipment.

[Source. GB/T 17045-2020, 3.9]

4 Classification and coding

4.1 Product classification

4.1.1 According to the connection relationship with the power grid

Power conversion systems, according to the connection relationship with the power grid,

can be classified into.

-- grid-connected and grid-disconnected switching type power conversion

systems;

-- grid-connected type power conversion systems;

-- grid-disconnected type power conversion systems.

4.1.2 According to the connected voltage level

Power conversion systems, according to the connected voltage level, can be classified

into.

-- Class A1 power conversion system, a power conversion system applied to

energy storage power stations connected to the power grid through a voltage

level of 10(6) kV and above, and with an AC terminal voltage of the power

conversion system not greater than 1 000 V;

-- Class A2 power conversion system, a power conversion system applied to

energy storage power stations connected to the power grid through a voltage

level of 10(6) kV and above, and with an AC terminal voltage of the power

conversion system greater than 1 000 V;

-- Class B1 power conversion system, a power conversion system applied to

connection to the distribution network through 10(6) kV;

-- Class B2 power conversion system, a power conversion system applied to

connection to the distribution network through 380 V;

-- Class B3 power conversion system, a power conversion system applied to

connection to the distribution network through 220 V.

4.1.3 According to installation and service environment

Power conversion systems, according to the installation and service environment, can

be classified into.

-- indoor type power conversion system, a power conversion system installed

inside a building or an enclosure with a protection grade of IP54 and above;

-- outdoor type power conversion system, a power conversion system with its

structure completely or partially exposed outdoors.

4.1.4 According to cooling method

Power conversion systems, according to the cooling method, can be classified into.

-- natural cooling type power conversion system;

-- air cooling type power conversion system;

-- liquid cooling type power conversion system.

4.1.5 According to topology structure

Power conversion systems, according to the topology structure, can be classified into.

Example 1.

A power conversion system with a DC voltage range of 580 V ~ 1 500 V, an AC terminal

rated voltage of 400 V, a rated power of 50 kW, and a single-stage conversion topology,

is marked as. EES-PCS-580~1 500 V-400 V-50 kW-S-xxxxx.

Example 2.

A power conversion system with a DC voltage range of 350 V ~ 700 V, an AC terminal

rated voltage of 800 V, a rated power of 200 kW, and a two-stage conversion topology,

is marked as. EES-PCS-350~700 V-800 V-200 kW-D-xxxxx.

Example 3.

A power conversion system with a DC operating voltage range of 500 V ~ 1 200 V, an

AC terminal rated voltage of 10 kV, a rated power of 5 MW, and a cascaded topology,

is marked as. EES-PCS-500~1 200 V-10 kV-5 MW-H-xxxxx.

5 Normal operating conditions

5.1 Environmental conditions

The power conversion system shall operate normally under the following

environmental conditions.

a) Temperature. -20 degrees C ~ +40 degrees C;

b) Relative humidity. <=95%;

c) For power conversion systems applied under high-altitude conditions above 2

000 m, comply with the relevant provisions of GB/T 20626.1;

d) For power conversion systems applied in marine climate, meet the salt spray

resistance requirements.

5.2 Electrical conditions for grid-connected operation

Grid-connected and grid-disconnected switching type power conversion systems and

grid-connected type power conversion systems shall operate normally under the

following power grid conditions.

a) The harmonic voltage shall not exceed the limits specified in GB/T 14549;

b) The interharmonic voltage shall not exceed the limits specified in GB/T 24337;

c) The power grid voltage deviation shall not exceed the limits specified in GB/T

12325;

d) The voltage fluctuation and flicker value shall not exceed the limits specified

in GB/T 12326;

e) The three-phase voltage unbalance factor shall not exceed the limits specified

in GB/T 15543;

f) The power grid frequency deviation shall not exceed the limits specified in

GB/T 15945.

5.3 Grid-disconnected operation conditions

Grid-connected and grid-disconnected switching type power conversion systems and

grid-disconnected type power conversion systems shall operate normally under the

following conditions.

a) The rated power of the load shall not be greater than the rated output power of

the power conversion system;

b) The load starting current shall not be greater than 1.2 times the rated current

of the power conversion system.

6 Appearance and protection grade

6.1 Appearance

The appearance of the power conversion system shall meet the following requirements.

a) The appearance shall be complete, without deformation, peeling, corrosion,

cracks or other phenomena;

b) The cabinet doors and switches shall operate flexibly;

c) The nameplate, signs and marks shall be complete and clear;

d) The texts and symbols shall be neat, standardized and correct.

6.2 Protection grade

The protection grade of the enclosure of the power conversion system shall meet the

following requirements.

a) The protection grade of indoor type power conversion systems shall be not

lower than IP20 specified in GB/T 4208;

b) The protection grade of outdoor type power conversion systems shall be not

lower than IP54 specified in GB/T 4208.

7 Basic functions

7.1 Start-up and shutdown

The power conversion system shall have the start-up and shutdown control function,

and be capable of starting up and shutting down the power conversion system according

to control switches or commands.

7.2 Power control

The power conversion system shall have active power control and reactive power

control functions, and be capable of continuously and smoothly adjusting active power

and reactive power as well as switching between charging and discharging according

to the control mode or received power control commands. Class A1 and Class A2 power

conversion systems should have primary frequency control and inertia response control

functions.

7.3 Grid-connected and grid-disconnected switching

The grid-connected and grid-disconnected switching type power conversion system

shall have the grid-connected and grid-disconnected switching function, and be capable

of switching from grid-connected mode to grid-disconnected mode according to the set

conditions, and establishing stable frequency and voltage; and be capable of switching

from grid-disconnected mode to grid-connected mode according to upper-level

commands, meeting the corresponding power requirements.

7.4 Alarm and protection

7.4.1 The power conversion system shall have a fault diagnosis function, and shall be

capable of giving alarms when abnormal conditions occur. The alarm should adopt

audible, visual and other indication methods. The alarm contents shall include. reverse

polarity connection, incorrect phase sequence of AC incoming line, DC voltage

abnormality, overcurrent, overtemperature, communication fault and cooling system

fault, etc.

7.4.2 After the power conversion system sends an alarm signal, it shall enter an

abnormal operation state or fault protection state.

7.4.3 The power conversion system shall have a fault information recording function,

be capable of recording fault and alarm information, and store the information.

7.5 Insulation resistance detection

7.5.1 The power conversion system shall have the DC terminal insulation resistance

detection function, and this function may be enabled or disabled as required.

7.5.2 When the insulation resistance value detected by the power conversion system is

lower than the set protection value, the power conversion system shall give an alarm

and stop operation.

Note. The protection value may be selected by default as the ratio of the maximum

DC voltage to 30 mA.

7.6 Communication

7.6.1 The power conversion system shall have the function of information interaction

with equipment such as battery management systems and monitoring systems.

7.6.2 The communication interfaces between the power conversion system and the

battery management system may adopt controller area network (CAN), RS-485,

Ethernet, wireless and other communication interfaces, and support communication

protocols such as CAN2.0B, Modbus, DL/T 860 (all parts), and Message Queuing

Telemetry Transport (MQTT).

7.6.3 The communication interface between the power conversion system and the

monitoring system may adopt Ethernet communication interface, and support

communication protocols such as Modbus TCP and DL/T 860 (all parts). Dual-network

redundant communication should be adopted.

7.7 Operation information monitoring

7.7.1 The power conversion system shall be capable of monitoring in real time the

voltage, current, power and battery status information of the DC terminal, as well as the

voltage, current, frequency and power information of the AC terminal.

7.7.2 The power conversion system shall be capable of monitoring in real time the

communication status between the power conversion system and equipment such as

battery management systems and monitoring systems.

7.8 Statistics

7.8.1 The power conversion system shall have a fault information statistics function to

realize the query of fault information.

7.8.2 The power conversion system should have charging energy and discharging

energy statistics functions to realize the query of charging and discharging energy

information.

7.9 Data display and storage

7.9.1 The power conversion system shall have a data display function and be capable

of displaying information such as operating status, operating parameters, protection

parameters and event records.

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