NB/T 106132021 PDF in English
NB/T 106132021 (NB/T106132021, NBT 106132021, NBT106132021)
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Technical specification of power quality measurement and evaluation for electric vehicle battery charging/swap station
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Standards related to (historical): NB/T 106132021
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NB/T 106132021: PDF in English (NBT 106132021) NB/T 106132021
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ENERGY INDUSTRY STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.020
CCS K 04
Technical specification of power quality measurement
and evaluation for electric vehicle battery
charging/swap station
ISSUED ON: APRIL 26, 2021
IMPLEMENTED ON: JULY 26, 2021
Issued by: National Energy Administration
Table of Contents
Foreword ... 4
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Measurement items ... 8
5 Measurement methods and requirements ... 8
5.1 Selection of measurement points ... 8
5.2 Measurement equipment requirements ... 9
5.3 Measurement duration and measurement conditions ... 9
5.4 Data record ... 10
5.5 Measurement methods ... 10
6 Measurement result evaluation ... 10
6.1 Supply voltage deviation ... 10
6.2 Harmonics ... 11
6.3 Interharmonics ... 11
6.4 Threephase unbalance ... 11
6.5 Voltage flicker ... 11
6.6 Rapid voltage changes ... 11
6.7 Power factor ... 11
6.8 Comprehensive index evaluation ... 12
Annex A (Informative) Schematic diagram of the connection of a typical electric
vehicle charging station or swap station to the power grid ... 13
Annex B (Normative) Measurement method for rapid voltage change ... 15
Annex C (Informative) A brief introduction to the influence of electric vehicle
charging on power quality of power supply points and the countermeasures
when it exceeds the standard ... 17
Annex D (Informative) Example of power quality comprehensive index
evaluation ... 20
Bibliography ... 27
Technical specification of power quality measurement
and evaluation for electric vehicle battery
charging/swap station
1 Scope
This Standard specifies the power quality measurement items, measurement
methods, measurement results evaluation requirements for electric vehicle
battery charging/swap station.
This Standard is applicable to the power quality measurement and evaluation
for electric vehicle battery charging/swap station powered by dedicated power
grids of 10kV and above. Electric vehicle charging stations or swap stations that
are powered by other voltage levels or not powered by the public grid can be
implemented by using this Standard as the reference.
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 123252008, Power quality  Deviation of supply voltage
GB/T 123262008, Power quality  Voltage fluctuation and flicker
GB/T 145491993, Quality of electric energy supply. Harmonics in public
supply network
GB/T 155432008, Power quality  Threephase voltage unbalance
GB/T 17626.30, Electromagnetic compatibility  Testing and measurement
techniques  Power quality measurement methods
GB/T 198622016, General requirements for monitoring equipment of power
quality
GB/T 243372009, Power quality  Interharmonics in public supply network
GB/T 293162012, Power quality requirements for electric vehicle
charging/battery swap infrastructure
GB/T 293172012, Terminology of electric vehicle charging/battery swap
infrastructure
GB 509662014, Code for design of electric vehicle charging station
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T
293172012 as well as the followings apply.
3.1 electric vehicle (EV) battery charging station
a place that provides charging services for electric vehicles and consists of
three or more electric vehicle charging equipment
[Source: GB/T 297812013, 3.4, modified]
3.2 EV battery swap station
a place that provides battery replacement services for electric vehicles and
charges power batteries
[Source: GB/T 293172012, 5.2, modified]
3.3 rapid voltage change; RVC
the phenomenon of rapid transition of the voltage rms value between two
voltage steady states
NOTE 1: The characteristic indexes that characterize the rapid voltage change event
include the start time, the end time (duration), the maximum voltage change ΔUmax, and
the steadystate voltage change ΔUss.
NOTE 2: The rapid voltage changes described in this document are limited to voltage
changes under steady state conditions and do not involve voltage changes under transient
conditions.
NOTE 3: The voltage steadystate is related to the rapid voltage change threshold.
3.4 voltage steadystate
100 consecutive halfcycle voltage rms; slide by half cycle time interval; the
average value after sliding does not exceed the threshold range of rapid voltage
changes based on the average value before sliding
power grid. The measurement duration shall not be less than 24h.
NOTE: The measurement duration can be adjusted according to the change cycle of the
actual load size of the charging station or swap station.
5.4 Data record
The measurement data and its recording interval are as follows:
a) Supply voltage deviation, harmonics, unbalance, power factor
measurement data recording time interval include 1min, 3min, 5min or
10min. It is advisable to use 1min;
b) The longterm voltage flicker value shall be continuously recorded and
stored a set of data every 2h;
c) For the captured rapid voltage change events, the characteristic values
are recorded, including the start time, duration, maximum voltage change
ΔUmax and steadystate voltage change ΔUss.
5.5 Measurement methods
5.5.1 The measurement methods of power supply voltage deviation, harmonics,
interharmonics, threephase unbalance and voltage flicker shall comply with
the requirements of GB/T 123252008, GB/T 145491993, GB/T 243372009,
GB/T 155432008 and GB/T 123262008 respectively.
5.5.2 The rapid voltage change measurement method is carried out in
accordance with Annex B.
5.5.3 The power factor correlation measurement method is as follows:
a) For the voltage and current measurement methods in the power factor
measurement process, see the power supply voltage class A
measurement method in GB/T 17626.30;
b) Conduct simultaneous calculation of active power, reactive power and
power factor.
6 Measurement result evaluation
6.1 Supply voltage deviation
Give the maximum value of positive and negative voltage deviations. Evaluate
whether the measurement results of power supply voltage deviation meet the
limit requirements of GB/T 123252008.
6.2 Harmonics
Give the total harmonic voltage distortion rate, the 2~50th harmonic voltage
content rate, and the 95% probability maximum value of the 2~50th harmonic
current. Evaluate whether the harmonic voltage content rate and the
measurement results of the harmonic current injected into the power supply
point meet the limit requirements of GB/T 145491993.
6.3 Interharmonics
Give the 95% probability maximum value of the interharmonic voltage content
rate in the frequency range of 0Hz~800Hz. Evaluate whether it meets the limit
requirements of GB/T 243372009.
6.4 Threephase unbalance
Give the threephase voltage unbalance, 95% probability maximum value and
maximum value of negative sequence current. Evaluate whether the three
phase voltage unbalance and the negative sequence current injected into the
power supply point meet the limit requirements of GB/T 155432008.
6.5 Voltage flicker
Give the maximum value of longterm voltage flicker. Evaluate whether the
voltage flicker measurement results meet the limit requirements of GB/T 12326
2008.
6.6 Rapid voltage changes
If a rapid voltage change event is captured, the characteristic index of the rapid
voltage change event is given. Analyze the correlation with changes in charging
load.
6.7 Power factor
Give the power factor at peak charging load. Evaluate whether the power factor
at the peak of the charging load meets the level A equipment limit 0.95 specified
in GB/T 293162012 or 0.95 specified in GB 509662014.
Annex C
(Informative)
A brief introduction to the influence of electric vehicle charging on
power quality of power supply points and the countermeasures when it
exceeds the standard
C.1 Overview
The change of electric vehicle charging and swap station load presents
randomness and diversity. It is closely related to the number of charging
vehicles in the region, the type of charging vehicles (residential vehicles or
commercial vehicles, etc.), and the charging cycle (working days or holidays)
and other factors. Therefore, different types of charging facilities and basic
power supply facilities shall be built according to different charging needs.
Reasonable matching of different charging strategies can reduce the impact of
the charging process on the power supply point of the power grid and promote
the coordinated development of electric vehicles and the power grid.
C.2 Impact of electric vehicle charging on power supply point
The influence of electric vehicle charging load on the power supply point is
mainly reflected in the increase in the load rate of the upper line and transformer
at the power supply point and the power quality exceeding the standard. The
increase in the load rate of lines and transformers leads to an increase in the
loss of the distribution network. It makes indirect deterioration of power quality
indexes. The nonlinearity, impact and uncertainty of electric vehicle charging
load are easy to cause power quality indexes such as supply voltage and
harmonics to exceed the standard. It is easy to cause problems such as voltage
harmonic oscillation and voltage mutation and affect the power quality of other
users in the surrounding area. To improve the quality of electric vehicle charging
power and ensure the coordinated development of electric vehicles and power
grids, it needs to start with infrastructure, such as optimal power supply point,
increase power supply point transformer and line power supply capacity. It is
also necessary to start with the power quality control method and take
measures to reduce the impact of power quality.
C.3 Countermeasures for power quality exceeding standard
C.3.1 Supply voltage deviation
The countermeasures for the situation where the power supply voltage
deviation exceeds the standard are suggested as follows:
a) If the deviation of the operating supply voltage of the charging station or
the swap station does not meet the requirements of the national standard
limit, and the deviation of the background power supply voltage does not
exceed the standard, it is advisable to put forward measures to alleviate
the problem of voltage deviation exceeding the standard in combination
with the change of charging power, especially the change of reactive
power (see B.3.6);
b) If the deviation of the operating power supply voltage of the charging
station or the swap station does not meet the requirements of the national
standard limit, and the deviation of the power supply voltage of the
background power grid also exceeds the standard, voltage control
measures shall be taken. If necessary, the power supply lines or power
supply transformers shall be expanded and transformed to reduce the
impact.
C.3.2 Harmonics and interharmonics
The countermeasures for the overstandard harmonics and interharmonics are
suggested as follows:
a) If the harmonic voltage, interharmonic voltage or injected harmonic
current exceeds the standard and the background power grid harmonic
voltage or interharmonic voltage does not exceed the standard,
corresponding harmonic control measures shall be taken at charging and
swap stations. Or combine the relationship between harmonics and
charging power trend and adopt an orderly charging strategy;
b) If the harmonic voltage, interharmonic voltage or injected harmonic
current exceeds the standard and the background power grid harmonic
voltage or interharmonic voltage also exceeds the standard, the reasons
shall be comprehensively analyzed, and corresponding remedial
measures shall be taken.
C.3.3 Threephase unbalance
If the threephase voltage unbalance and the negative sequence current
injected into the power supply point exceed the standard, the charging and
auxiliary power loads in the charging and swap stations shall be reasonably
arranged according to the balance principle, or corresponding control measures
shall be taken.
C.3.4 Voltage flicker
If the voltage flicker exceeds the standard, corresponding voltage control
measures shall be taken.
a) UPQI (avg) represents the normalized average value of each item index
at the measurement point.
b) UPQI (max) represents the normalized maximum value of each item index
at the measurement point.
c) UPQI (node) represents the unified power quality index value of the
measurement point. If the measurement point harmonics, voltage flicker
and other project indexes are all less than 1 after normalization, the value
is the maximum value among the normalized values of each project index.
Otherwise, the value is 1 and gradually accumulates the part of each
exceeding index value minus 1.
d) UPQI (system) represents the unified power quality index value of a
charging and swap station system. Similar approach to single
measurement point: If the UPQI (node) value of each measurement point
is less than 1, the value is the maximum index of UPQI (node) in each
measurement point. Otherwise, the value is 1 and the remaining value
after subtracting 1 from the UPQI (node) value of each exceeding
measurement point is gradually accumulated.
e) UPQI (system/avg) represents the improved unified power quality index
value (referred to as the improved value). If the indexes of each point are
less than 1, the UPQI (system/avg) is the maximum index of the UPQI
(node) value of each measurement point. Otherwise, UPQI (system/avg)
is the average of the sum of the remaining values after subtracting 1 from
the UPQI (node) value of each overstandard point and the number of
nodes.
f) The power quality comprehensive evaluation index results of system 1 are
shown in Table D.5. When the UPQI (avg) results are all qualified, the
conclusion of the characterization measurement is wrong and unscientific.
When the UPQI (max) index value does not affect the measurement
conclusion, but the corresponding measurement point 2 and
measurement point 3 are the same, the measurement point 2 has two
indexes exceeding the standard, and the measurement point 3 has one
index exceeding the standard, it shows that the UPQI (max) index is also
unreasonable. The UPQI (node) index value can also consider the
comprehensive hazards of different indexes without affecting the
measurement conclusion. It has good applicability, so the comprehensive
evaluation index of single measurement point power quality shall use
UPQI (node) index.
Table D.5  Evaluation results of comprehensive indexes of system 1
power quality
...... Source: Above contents are excerpted from the PDF  translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
