NB/T 32004-2018 (NB/T32004-2018, NBT 32004-2018, NBT32004-2018) & related versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Standard Title (Description) | See Detail | Status | Similar PDF |
| NB/T 32004-2018 | English | 1220 |
Add to Cart
|
0-9 seconds. Auto delivery.
|
Technical specification of PV grid-connected inverter
|
NB/T 32004-2018
| Valid |
NBT 32004-2018
|
| NB/T 32004-2013 | English | 520 |
Add to Cart
|
0-9 seconds. Auto delivery.
|
Technical specification of grid-connected PV inverter
|
NB/T 32004-2013
| Obsolete |
NBT 32004-2013
|
Buy with any currencies (Euro, JPY, KRW...): NB/T 32004-2018 Preview this PDF: NB/T 32004-2018
NB/T 32004-2018: PDF in English (NBT 32004-2018)
NB/T 32004-2018
NB
ENERGY INDUSTRY STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
ICS 29.120.01
K 46
Filing number: 64298-2018
Replacing NB/T 32004-2013
Technical specification of PV grid-connected inverter
ISSUED ON: APRIL 03, 2018
IMPLEMENTED ON: JULY 01, 2018
Issued by: National Energy Administration
Table of Contents
Foreword ... 3
1 Scope ... 8
2 Normative references ... 8
3 Terms and definitions ... 11
4 Inverter type ... 22
5 Environmental and use requirements ... 23
6 Safety requirements ... 24
7 Basic functional requirements ... 45
8 Performance requirements ... 45
9 Protection requirements ... 62
10 Identification and documentation ... 65
11 Test method ... 70
12 Inspection rules ... 115
Appendix A (Normative) Symbols used on equipment identification ... 119
Appendix B (Normative) Humidity preconditioning ... 120
Appendix C (Informative) Measurement of inverter efficiency ... 121
References ... 128
Technical specification of PV grid-connected inverter
1 Scope
This standard specifies the product types, technical requirements and test
methods of photovoltaic grid-connected inverters used in photovoltaic (PV)
power generation systems.
This standard applies to photovoltaic grid-connected inverters connected to the
PV source circuit whose voltage does not exceed 1500V DC and whose AC
output voltage does not exceed 1000V. The preparatory photovoltaic inverter
where the integrated step-up transformer is grid-connected to the grid of 35kV
and below voltage level can refer to this standard.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 2423.1-2008 Environmental testing - Part 2: Test methods - Tests A:
Cold
GB/T 2423.2-2008 Environmental testing - Part 2: Test methods - Tests B:
Dry heat
GB/T 2423.3-2016 Environmental testing - Part 2: Testing method - Test Cab:
Damp heat, steady state
GB/T 2423.4-2008 Environmental testing for electric and electronic products
- Part 2: Test method - Test Db: Damp heat, cyclic ( 12h+12h cycle)
GB/T 2423.10-2008 Environmental testing for electric and electronic
products - Part 2: Tests methods - Test Fc: Vibration (sinusoidal)
GB/T 2828.1-2012 Sampling procedures for inspection by attributes - Part 1:
Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot
inspection
GB/T 3805 Extra-low voltage (ELV) - Limit values
GB/T 16842-2016 Protection of persons and equipment by enclosures -
Probe for verification
GB 16895.3 Low-voltage electrical installations - Part 5-54: Selection and
erection of electrical equipment - Earthing arrangements and protective
conductors
GB/T 16895.10-2010 Low-voltage electrical installations - Part 4-44:
Protection for safety - Protection against voltage disturbances and
electromagnetic disturbances
GB 16895.21 Electrical installations of buildings - Part 4-41: Protection for
safety - Protection against electric shock
GB/T 16935.1-2008 Insulation coordination for equipment within low-voltage
systems - Part 1: Principles requirements and tests
GB/T 17626.2 Electromagnetic compatibility (EMC) - Testing and
measurement techniques - Electrostatic discharge immunity test
GB/T 17626.3 Electromagnetic compatibility- Testing and measurement
techniques - 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 8: Testing and
measurement techniques - Power frequency magnetic field immunity test
GB/T 17626.11 Electromagnetic compatibility - Testing and measurement
techniques - Voltage dips, short interruptions and voltage variations
immunity tests
GB/T 17626.12 Electromagnetic compatibility - Testing and measurement
techniques - Ring wave immunity test
GB/T 17626.18 Electromagnetic compatibility - Testing and measurement
techniques - Damped oscillatory wave immunity test
GB/T 17626.34 Electromagnetic compatibility - Testing and measurement
techniques - Voltage dips, short interruptions and voltage variations
4 Inverter type
4.1 Classification by the number of output phases on the AC side
According to the number of output phases on the AC side, it can be divided into:
- Single-phase inverter;
- Three-phase inverter.
4.2 Classification by installation environment
According to the installation environment, it can be divided into:
- Indoor Type I (with temperature adjustment device);
- Indoor type II (without temperature adjustment device);
- Outdoor type.
4.3 Classification by electrical isolation
According to the electrical isolation, it can be divided into:
- Isolated type;
- Non-isolated type.
4.4 Classification by access voltage level
According to the access voltage level, it can be divided into:
- A type inverter.
Refers to photovoltaic inverters used in photovoltaic power stations that are
connected to the grid through voltage levels of 35 kV and above, or
connected to the public grid through voltage levels of 10 kV and above;
- Type B inverter.
Refers to photovoltaic inverters used in photovoltaic power generation
systems that are connected to the grid through a voltage level of 380 V and
connected to the user side of the grid through a voltage level of 10 kV and
below, including inverters used in residential environments and directly
connected to residential low-voltage power supply network facilities.
Note: In the electromagnetic compatibility test of the inverter connected to
the grid via an independent power transformer, the type A limit is adopted.
resistance to material aging caused by ultraviolet (UV) radiation; it needs to be
evaluated for resistance to ultraviolet radiation or provide a third-party qualified
test report. After the UV radiation test, the sample shall show no obvious signs
of deterioration, including cracks or breaks. If the degradation of the component
does not affect the protection it provides, the requirements of this clause can
be ignored.
5.8 Pollution degree
In order to facilitate the determination of electrical clearance and creepage
distance, the environmental pollution levels are classified as follows:
1) Pollution level 1: No pollution or only dry non-conductive pollution.
2) Pollution level 2: Generally speaking, only non-conductive pollution occurs,
but temporary conductive pollution caused by condensation must be taken
into consideration.
3) Pollution level 3: Conductive pollution, or dry non-conductive pollution
becomes conductive pollution due to condensation.
4) Pollution level 4: Persistent conductive pollution, such as pollution caused
by conductive dust or rain and snow.
Outdoor type and indoor type II inverters shall meet pollution level 3
environment; indoor type I inverters shall meet pollution level 2 environment.
For special purposes and micro-environment, other pollution levels can be
considered. If the inverter is scheduled to be used in a pollution level 4
environment, measures must be taken to reduce the pollution level of the micro-
environment inside the inverter to levels 1, 2, 3.
6 Safety requirements
6.1 Temperature limit
The temperature of the materials and components used in the equipment must
not exceed the limits specified in Table 1 to Table 3. In general, if the inverter's
related components or their surface temperature does not change more than
1 °C/h, it is considered that the inverter has reached a thermally stable state.
Under full power conditions, the temperature rise test lasts for up to 7 hours
(simulating one day's sun exposure), except that if a longer test can prove that
it will produce greater danger.
1) The voltage of live parts is less than or equal to the specified safe
voltage - It is accessible;
2) The voltage of live parts is greater than the specified safe voltage - It is
not accessible, meanwhile there must be sufficient electrical clearance
between the live parts.
Note: The safety voltage limit is specified in accordance with the requirements
of the standard GB/T 3805.
b) The inverter adopts enclosure or shielding protection; it shall be inspected
according to the method of 11.2.2.1, to prevent the dangerous live parts
from being touched.
6.2.1.2.3 Maintenance personnel contact area
When the enclosure needs to be opened during installation or maintenance,
meanwhile the inverter needs to be energized, protection against contact shall
be provided for live parts with a voltage greater than the specified safe voltage
that may be unintentionally touched during the maintenance process. The
protection requirements shall be inspected according to the method of 11.2.2.1.
6.2.1.3 Insulation protection of live parts
Insulation shall be determined according to the impulse voltage, temporary
overvoltage or working voltage of the inverter; the most severe condition shall
be selected according to the requirements of 6.2.3. Without the use of tools, the
insulation protection shall not be removed.
6.2.2 Requirements for indirect contact protection
6.2.2.1 General requirements
a) In the case where the insulation between the contactable conductor and
the live parts of the inverter fails, in order to prevent contact with the
current that has the risk of electric shock, protection of indirect contact is
required. There are generally 2 ways of indirect contact protection:
Protective class I: Basic insulation and protective grounding;
Protective class II: Double insulation or reinforced insulation.
b) If the indirect contact protection depends on the installation method, the
installation manual shall clearly indicate the relevant hazards and specify
the installation method in detail.
c) Circuits that use insulation for indirect protection shall meet the
requirements of 6.2.3.
external protective grounding conductor shall use a separate connection
method and cannot be used as a mechanical component for other connections.
Short-circuit protection devices such as fuses shall not be installed in the
grounding loop.
The connection of the protective conductor shall be marked with the seventh
symbol in Appendix A; the protective grounding cable shall be in alternative
yellow and green colors.
6.2.2.2.5 Contact current
In order to maintain safety when the protective grounding conductor is damaged
or disconnected, for the inverter connected through the plug, the measured
contact current shall not exceed 3.5mA a.c. or 10mA d.c.; for all other inverters,
if the contact current exceeds 3.5mA a.c. or 10mA d.c., one or more of the
following protective measures shall be adopted and the 15th warning sign of
Appendix A shall be marked:
1) Use a fixed connection and the cross-sectional area of the protective
grounding conductor is at least 10 mm2 (copper) or 16 mm2 (aluminum);
2) Adopt a fixed connection and automatically disconnect the power supply
when the protective grounding conductor is interrupted;
3) Use the industrial connector specified in GB/T 11918.1 for connection;
meanwhile the minimum cross-sectional area of the protective grounding
conductor in the multi-conductor cable is 2.5 mm2.
6.2.3 Insulation coordination
6.2.3.1 Insulation voltage
The impulse withstand voltage and temporary overvoltage are specified in Table
5 according to the circuit system voltage and overvoltage level. The overvoltage
category shall be judged according to the description of clause 443 in GB/T
16895.10-2010.
Under normal circumstances, the overvoltage level of the grid power circuit is
considered to be level III, whilst the overvoltage level of the PV circuit that is
galvanically isolated from the grid power circuit is set to level II; for inverters
that do not have galvanic isolation between the grid power circuit and the PV
circuit, determine the pulse withstand voltage according to the overvoltage level
of the grid power circuit, compare it with the pulse withstand voltage of the PV
circuit, select the larger one as the pulse withstand voltage of the combined
circuit of the PV circuit and the grid power circuit.
For other circuits, make judgement according to the following requirements
of the capacitor after the inverter is powered off. If the discharge time of the
capacitor cannot be accurately calculated, it shall be measured.
6.4 Mechanical protection requirements
6.4.1 General requirements
Operating the inverter under normal use conditions and any fault conditions
shall not cause mechanical hazards. The edges, protrusions, corners, holes,
shields, handles and other parts that can be touched by the operator must be
smooth and free of burrs; meanwhile it shall not cause injury during normal use.
6.4.2 Requirements for moving parts
The moving parts of the inverter (such as the cooling fan, etc.) shall not cause
injury to the operator's body; the dangerous moving parts of the equipment shall
provide adequate protection measures.
During routine maintenance, if the operator is inevitably required to touch
dangerous moving parts due to technical reasons, such as adjusting the moving
parts, the inverter must provide all the following precautions before allowing the
operator to touch:
a) It can be accessed only with the help of tools;
b) The instruction manual shall state that: the operator must be trained to be
allowed to perform dangerous operations;
c) The cover or parts that can be disassembled to reach the dangerous part
must have warning signs, to prevent accidental contact by untrained
operators;
d) There is no automatic reset thermal circuit breaker, overcurrent protection
device or automatic timing start device, etc.
For inverters that have not taken the above precautions, the test finger shall not
touch the dangerous moving parts from any direction with insignificant force.
For the hole to prevent the test finger from entering, it is necessary to further
use a straight test finger without joints and apply a 30N force to test. If such a
test finger can enter the hole, a new test finger shall be used for the test; if
necessary, the test finger shall be pushed into the hole with a force of 30N.
6.4.3 Stability
If the inverter is not fixed to the building component, it must have physical
stability during normal use. After the operator opens the door or drawer of the
inverter, the inverter itself needs to be able to maintain stability. If not, the
than the conductor cross-section as specified in the temperature rise test of
11.2.1. The conductors that can be used for the terminal shall be of the same
type (hard wire or flexible wire, single-core wire or multi-strand wire).
6.4.6.3 Design of terminal blocks
The terminal shall be designed so that it can clamp the wire between the metal
surfaces with sufficient contact pressure without damaging the wire. The design
or configuration of the wiring terminal shall ensure that the wire does not slip off
when the screw or nut holding the wire is tightened.
Terminals shall be equipped with appropriate accessories for fixing the wires
(such as nuts and washers).
The terminal shall be fixed so that the accessories holding the wire are
tightened or loosened,
- The terminal itself will not loosen;
- The internal wiring does not bear stress;
- The clearance and creepage distance will not be reduced to less than the
specified values in 6.2.3.3 and 6.2.3.4.
6.5 Fire hazard protection
6.5.1 General requirements
Inside the inverter and outside the inverter, use appropriate materials and
components and use the appropriate structures, in order to reduce the risk of
ignition and flame spread.
- Method 1: Select and use components, wiring and materials that can
reduce the risk of ignition and the possibility of flame spread; use a fireproof
enclosure if necessary.
Note: For inverters with a large number of components, method 1 is
recommended.
- Method 2: All simulation tests will not cause components to ignite, or bring
the temperature to the ignition point, or cause other signs of fire hazard.
Therefore, this type of inverter or part of the inverter does not require a
fireproof enclosure.
Note: For inverters with a relatively small number of components, method
2 is recommended.
6.5.2 Flammability requirements of materials
b) For non-isolated inverters or inverters that are isolated but their leakage
current does not meet the requirements, faults shall be indicated and their
access to the grid shall be restricted.
At this time, it is allowed to continue to monitor the insulation resistance
of the square array; when the insulation resistance meets the above
requirements, it is allowed to stop the alarm and also allow to connect to
the grid.
6.7.1.2 Inverters requiring functional grounding
If an inverter with an integrated resistor is needed to realize the functional
grounding of the photovoltaic array, the inverter shall meet the requirements of
a) and c), or b) and c) of this clause.
a) Including the preset resistance for functional grounding, the total
grounding resistance shall not be less than R=Umaxpv/30mA. The expected
insulation resistance value can be calculated based on the insulation
resistance of 40MΩ per square meter of the square array when the area
of the connected photovoltaic array is known. It can also be calculated
based on the rated power of the inverter and the efficiency of the worst
photovoltaic array to which the inverter can be connected.
b) If the resistance is less than that specified in a), then the inverter shall be
able to provide a method to monitor the current through the resistor and
any parallel network line (such as the test line) during operation. If the
response time of the sudden current exceeds the limit in Table 14, the
resistor shall be disconnected or use other methods to limit current. If it is
a non-isolated inverter, or an inverter that is isolated but cannot meet the
minimum leakage current requirements, it must be disconnected from the
grid.
c) Before normal operation, the inverter must be able to test the grounding
resistance.
6.7.2 Testing of array residual current
6.7.2.1 General requirements
a) Ungrounded photovoltaic arrays working above the safe voltage level may
cause electric shock hazards. The inverter is not isolated, or although it
has isolation measures but cannot guarantee that the contact current is
within a reasonable range, if the user touches the live part of the array and
the ground at the same time, the connection between the grid and the
ground (such as the grounded neutral line) will provide a loop for the
contact current, thereby creating a risk of electric shock. This hazard can
be eliminated by the protection method described in 6.7.2.4, or the contact
measured continuous maximum input current or power shall not exceed 110%
of the nominal maximum input value; the measured inverter working voltage
range shall not exceed the value declared by the manufacturer plus the voltage
control accuracy declared by the manufacturer.
8.1.2 Output requirements
When the inverter is working within the normal input and output operating
voltage range, the continuous output current of the inverter shall not exceed
110% of the nominal maximum continuous output current. At this time, the over-
current protection device and the over-temperature protection device shall not
act.
When the inverter is working within the normal input and output working voltage
range, it can continuously output the nominal rated power, meanwhile it shall
not exceed 110% of the nominal rated output power. At this time, the over-
current protection and over-temperature protection devices shall not operate.
8.2 Efficiency requirements
For the inverter, the efficiency of its energy conversion is determined by
dynamic MPPT efficiency, static MPPT efficiency and conversion efficiency.
The maximum conversion efficiency ηmax and the average weighted total
efficiency ηt,c of the inverter shall not be lower than the requirements in Table
15. It is required that the dynamic MPPT efficiency calculated by the test shall
not be less than 90%. Among them, the average weighted total efficiency is the
average weighted efficiency of static MPPT efficiency and conversion efficiency
under different voltages calculated according to the efficiency weighting
coefficients of typical solar resource areas in China.
The conversion efficiency includes all auxiliary power and control power losses.
For inverters with external independent dedicated isolation transformers, they
may be assessed according to the conversion efficiency limits of non-isolated
inverters without transformers; they can also be assessed according to the
conversion efficiency limits of isolated inverters with isolation transformers. The
loss includes loss of the isolation transformer. The conversion efficiency limit of
the preparatory photovoltaic grid-connected inverter device can refer to the limit
of the isolated inverter, which needs to include the loss of the isolation
transformer.
Pout - Total active power output of the inverter;
Qout - The total reactive power output of the inverter.
8.3.1.3 Three-phase current unbalance
When the inverter is in normal operation, the negative sequence three-phase
current unbalance degree shall not exceed 2%; it shall not exceed 4% in a short
time.
8.3.1.4 DC component
When the inverter is operating normally, the DC current component fed to the
grid shall not exceed 0.5% of its output current rating.
8.3.2 Active power control
8.3.2.1 Change rate control
The active power change rate of the inverter during normal operation shall not
exceed ±10% PN/min, including when the inverter is started and stopped, the
actual active power change rate caused by the decrease in solar irradiance as
allowed to occur during the operation of the photovoltaic power station exceeds
the limit.
Class A inverters shall be able to set the rate of change of active power when
starting and stopping, the active power control error shall not exceed ±5% PN
when starting and stopping; the maximum peak current output on the AC side
during starting and stopping shall not exceed 1.1 times the rated AC peak
current value. Class B inverters can be implemented by reference, but do not
need to have the function of start-stop change rate control.
8.3.2.2 Setpoint control
Class A inverters shall have the ability to continuously and smoothly adjust
active power; be able to accept commands from the power control system to
adjust the active power output value. The control error shall not be greater than
±1% PN; the response time shall not be greater than 1s. Class B inverters shall
be implemented by reference.
8.3.2.3 Over-frequency derating control
Class A inverter should have over-frequency derating control function. When
the system frequency deviation is greater than +0.03Hz (allowable error range:
±0.01Hz) and the inverter's active power output is greater than 10% PN, the
inverter shall be able to adjust the active output; the active power adjustment
curve is as shown in Figure 2. The specific requirements are as follows:
are correctly connected, the inverter shall be able to work normally.
9.3.2 AC phase loss protection
When the AC output phase of the inverter is missing, the inverter will
automatically protect and stop working. The inverter shall be able to operate
normally after correct connection.
9.4 DC input overload protection
9.4.1 If the inverter's input terminal does not have the power limiting function,
protection is required when the inverter's input power exceeds 1.1 times the
nominal maximum DC input power.
9.4.2 If the inverter's input terminal has a power limiting function, when the
output power of the photovoltaic array exceeds the maximum DC input power
allowed by the inverter, the inverter shall automatically limit the current and work
at the maximum AC output power allowed.
9.5 Output short circuit protection
When the inverter is turned on or running, if a short circuit on the output side is
detected, the inverter shall be able to automatically protect. It is required that
there is no electric shock hazard in the accessible conductive parts, meanwhile
the parts with electric hazard and mechanical hazard shall not be touched. If
the recorded short-circuit current exceeds the maximum rated current of the
circuit, the measured maximum short-circuit current must be written in the
installation manual.
9.6 Reverse discharge protection
When the DC side voltage of the inverter is lower than the allowable working
range or is in the shutdown state, there shall be no reverse current flowing out
of the inverter DC side.
9.7 Anti-islanding protection
Class B inverters shall have the ability to quickly monitor islanding and
immediately disconnect from the grid. The anti-islanding protection action time
shall be no more than 2s, meanwhile a warning signal shall be sent at the same
time. The islanding protection shall also be coordinated with the grid-side line
protection.
9.8 Restoration of grid connection
After the Class B inverter trips due to abnormal voltage or frequency, when the
voltage and frequency return to normal, the photovoltaic inverter shall be
30 years.
The compliance of this clause is verified by inspection.
10.1.2 Rated parameters
Unless there are special requirements in other parts of this standard, the
following applicable parameters shall be marked on the inverter:
- Input voltage range, maximum input voltage, voltage type, maximum input
current, maximum DC short-circuit current;
- Output voltage level, voltage type, frequency, maximum continuous output
current, rated output power;
- IP protection degree, protection level.
Compliance with this clause is verified by inspection.
10.2 Documentation
10.2.1 General requirements
10.2.1.1 The document needs to explain the safe operation and installation of
the inverter; if necessary, it can also give instructions on the maintenance of the
inverter and the following content:
1) Explain the markings on the inverter, including the symbols used.
2) The location and function of the terminals and the controller.
3) All parameters and specifications related to the installation and operation
of the inverter, including the following environmental parameters, as well
as......
......
| Standard ID | NB/T 32004-2018 (NB/T32004-2018) | | Description (Translated English) | Technical specification of PV grid-connected inverter | | Sector / Industry | Energy Industry Standard (Recommended) | | Classification of Chinese Standard | K46 | | Classification of International Standard | 29.120.01 | | Word Count Estimation | 84,814 | | Date of Issue | 2018-04-03 | | Date of Implementation | 2018-07-01 | | Older Standard (superseded by this standard) | NB/T 32004-2013 | | Quoted Standard | GB/T 2423.1-2008; GB/T 2423.2-2008; GB/T 2423.3-2016; GB/T 2423.4-2008; GB/T 2423.10-2008; GB/T 2828.1-2012; GB/T 3805; GB/T 4207; GB/T 4208; GB 4824; GB/T 5169.10; GB/T 5169.11; GB/T 5169.17; GB/T 5465.2-2008; GB 7251.1-2013; GB/T 11918.1; GB/T 12113-200 | | Drafting Organization | Shanghai Electrical Equipment Testing Co., Ltd. | | Administrative Organization | China Electrical Equipment Industry Association | | Regulation (derived from) | National Energy Administration Announcement No. 4 of 2018 | | Summary | This standard specifies the product types, technical requirements and test methods for photovoltaic grid-connected inverters used in photovoltaic (PV) power generation systems. This standard is applicable to photovoltaic grid-connected inverters connected to the PV source circuit voltage not exceeding 1500V DC and AC output voltage not exceeding 1000V. Pre-installed PV grid-connected inverters with integrated step-up transformers connected to the grid of 35kV and below can be implemented. |
|