NB/T 31041-2019Technical specification for converter of offshore doubly-fed wind turbine generator (English PDF)

3.1 Converter control unit(CCU)

The control system of the converter, which mainly includes the core processor, coprocessor, input and output interface, communication interface, etc., is to control the converter An important component that completes various functions and performs data interaction with related peripherals.

3.2 Redundancy

Repeatedly configure some components of the system. When the system fails, the redundantly configured components intervene and assume the work of the failed component, thereby reducing Less system downtime.

3.3 Line-side converter power factor

The ratio of active power to apparent power at the AC side of the grid-side converter.

3.4 Common mode voltage

The average value of the phasor voltage that appears between each conductor and the specified reference point (usually the ground or the frame). Or add at the same time One third of the input voltage between the two measurement terminals of the voltmeter and the specified common terminal, that is, (Va Vb Vc)/3.

3.5 Differential mode voltage

The potential difference between phases.

3.6 4 Technical requirements

4.1 Product type and main parameters

4.1.1 Product Type

The product types are divided into.

a) According to the ambient temperature, it is divided into normal temperature type and low temperature type;

b) According to the cooling method of the power module, it is divided into air-cooled, liquid-cooled, mixed-cooled, etc., and the liquid-cooled type should be adopted.

4.1.2 Grid side voltage level (kV)

The grid side voltage level of the converter preferentially adopts the following series.

Note: The voltage level beyond the above priority series is determined by the user and the manufacturer through negotiation.

4.2 Conditions of use

4.2.1 Environmental conditions for normal use

a) According to 4.2 of NB/T 31094-2016, the ambient temperature for normal use of the converter is divided into. Normal temperature type. -10 °C~+45 °C. Low temperature type. -20 °C~+45 °C;

b) Relative air humidity. <=95% (when below 20 °C);

c) Altitude. <=1000 m;

d) Influence of salt spray. Yes;

e) Mould influence. Yes.

4.2.2 Normal test environmental conditions

Mainly including the use of climatic conditions, the converter should be tested under the following atmospheric environment.

a) Ambient temperature. -5 °C~40 °C;

b) Relative humidity. 30%~90% (below 20°C);

c) Atmospheric pressure. 86kPa~106kPa.

4.2.3 Ambient temperature during storage and transportation

The limit temperature range of ambient air during storage and transportation of the converter is. -40 °C ~ +70 °C.

4.2.4 Electrical conditions for normal use

4.2.4.1 Grid frequency variation range

The range of power grid frequency. 47.5 Hz~51.5 Hz.

4.2.4.2 Grid voltage fluctuation range

If the grid voltage is within ±10% of the rated value, the converter should be able to operate normally.

When the grid voltage exceeds the above range, the user shall negotiate with the manufacturer.

4.2.4.3 Grid voltage unbalance

According to the provisions of GB/T 15543-2008 in 4, the voltage unbalance of the power grid should not exceed 2%, and it should not exceed 4% in a short time.

4.3 Performance requirements

4.3.1 Structure and appearance requirements

a) The cabinet body should adopt steel anti-corrosion design;

b) The cabinet is provided with a public grounding point, and all parts of the cabinet shall be well connected to the public grounding point, and electric shock prevention measures shall be provided. Complete protective grounding;

c) Dehumidification device should be installed inside the cabinet;

d) The power supply of the internal control unit of the cabinet should be powered by a shielded isolation transformer;

e) The cabinet design should meet the installation and maintenance requirements in the tower and engine room, and be easy to install, debug and maintain;

f) The selection and installation process of buttons, switches, display screens, signal lights and alarm devices of the cabinet, as well as the way of entering and exiting the cabinet Should match the protection level of the cabinet;

g) The cabinet has a firm structure and should be able to withstand the influence of electricity, heat, mechanical strength and vibration on the equipment in the operating environment;

h) The operating device should be installed in a position that is easy for the operator to operate, and the emergency stop button should be placed in the most conspicuous and easy-to-operate position of the cabinet. And the button itself is equipped with a protective cover;

i) The surface of the cabinet body should be smooth and without unevenness, and coating treatment should be adopted, and the color of the paint layer should be uniform, and there should be no blistering, cracks and flow.

The cabinet door should be able to open and close flexibly within an angle of not less than 90 degrees;

j) The cabinet structure should be simple and open, easy to reach, and the corrosion-prone surface design should be as smooth as possible. Any necessary reinforcements, Joints and pipes should be arranged as far as possible in places with low corrosion risk, and hollow parts that are difficult to maintain should be welded firmly. other Metal exposed to the air should be protected by plating. Generally, electroplating should be used.

4.3.2 Requirements for electrical components

a) The components listed in Table 1 should meet the requirements of 7.1.1.2 in GB/T 3783-2008;

b) All solid insulating parts except ceramic materials should have heat resistance, that is, after the parts are subjected to the heat resistance test, the indentation spans the largest dimension The inch is not more than 2mm;

c) All solid insulating parts except ceramic materials should have flame resistance, that is, the parts will not Ignition, or even if ignition occurs, the combustion and heat can be completely extinguished within 30s after the glow wire (or needle flame) is removed, and the indication Silk paper does not burn. At the same time, all plastic parts should also have flame retardancy, that is, after flame retardance test, these parts burn or damage The length of the part is not more than 60mm;

d) All components should be installed in accordance with the manufacturer's instructions and meet the requirements of their respective standards.

4.3.3 Electrical connection requirements

a) The correctness of each electrical connection should be ensured. Auxiliary devices such as capacitors, fast fuses, electronic components, etc. should be screened before assembly, Test and confirm that it has normal functions. The cross-sectional area of the cable and the crimping of the cable head should meet the maximum current carrying capacity of the converter. cloth The line should be in accordance with 6.7 of GB/T 3797-2016;

b) All exposed conductors, connectors, terminal blocks, soldering points and circuit boards should be treated with anti-corrosion and moisture-proof treatment;

c) The conductive part should be made of copper or copper alloy;

d) When non-aluminum electrical accessories are connected to aluminum parts, appropriate measures should be taken to prevent electrolytic corrosion;

e) The wiring process and electrical connection in the cabinet should consider the influence of external insulation corrosion and condensation on the creepage distance, and the high humidity on the air insulation The influence of fate;

f) Magnetic materials should not be used for shielding when multi-core cables are used in the AC system;

g) When single-core cables need to be connected in parallel, the type, length, and end technology of the parallel cables must be the same;

h) Permanent anti-corrosion non-magnetic clamps and brackets should be used for fixed cables;

i) Shielded cables or cables in metal pipes, shielded nets or metal pipes should be equipotentially connected.

4.3.4 Measures to prevent electric shock

The protective ground terminal shall have appropriate anti-corrosion measures, and the rest shall be in accordance with the provisions of 5.12 in JB/T 5777.2-2002.

4.3.5 Insulation performance

4.3.5.1 Insulation resistance

Under the normal test atmospheric conditions specified in 4.2.2, between each independent circuit of the converter and the exposed conductive part, as well as with each independent Between the circuits, use a DC megohmmeter to measure the insulation resistance, which should not be less than 1 Mohm.

4.3.5.2 Dielectric strength

Under the normal test atmospheric conditions specified in 4.2.2, the converter should be able to withstand a power frequency withstand voltage test with a frequency of 50 Hz and a duration of 1 min. No breakdown flashover and component damage.

4.3.5.3 Electrical clearance and creepage distance

The electrical clearance and creepage distance between the live circuits of the converter and between the live parts, conductive parts, and grounding parts should comply with Table 2. Requirements.

4.3.6 Load control function

Within the allowable generator speed range and specified load level, the converter should be able to normally control the grid-connected operation and phase of the wind turbine. Response power output.

4.3.7 Overload capacity

The overload capacity of the converter, including the motor side and the grid side, should match the overload capacity of the doubly-fed generator. In the converter rated operation bar Under 110% of the nominal current, the continuous running time should be no less than 1 min.

4.3.8 Protection function

The converter should have at least the following protection functions.

a) Overcurrent protection;

b) Lack of phase protection;

c) Phase sequence error protection;

d) Protection of grid voltage imbalance;

e) Ground fault protection;

f) Cooling system failure protection;

g) Over temperature protection;

h) Generator under/over speed protection;

i) Over/under voltage protection;

j) Communication failure alarm;

k) Over/under frequency protection;

l) Power grid power failure protection;

m) Grid current imbalance protection;

n) Power device hardware protection;

o) Surge over-voltage protection; p) Lightning protection.

The lightning protection of the converter shall meet the requirements of GB/T 21714.4. The converter should be installed with a lightning electromagnetic pulse protection system (LEMS)

In the area of wind power equipment, one of the following two situations is met.

--It is recommended to use a surge protector (SPD) external to the converter to suppress the impact of induced lightning. Load the variable flow of SPD device The minimum withstand the nominal discharge current In is 20kA (waveform 8/20µs);

--The converter itself can withstand the minimum nominal discharge current In of 20kA (waveform 8/20µs).

In addition, the protection shutdown should be able to be released by remote or local self-reset after the protection conditions are released.

4.3.9 Temperature rise

Under the operating conditions of nominal current, after the thermal stability of each element, the limit temperature rise of each part of the converter is shown in Table 3.

4.3.10 Grid-connected cut-in current

The grid-connected cut-in current of the generator should not exceed the peak value of the stator rated current.

4.3.11 Communication requirements

The converter should have a corresponding communication interface and be able to communicate with the main control system of the unit. The communication protocol can be CDT, Modbus, CANopen or PROFIBUS etc.

4.3.12 Power factor

Including the grid side of the converter and the output end of the unit, the converter should have a certain power factor adjustment capability, and the grid side of the converter should have Certain power factor adjustment capability, the power factor can be adjusted between ±0.95.

4.3.13 Common mode voltage requirements

The filter link or filter of the converter should be designed to match the common mode voltage tolerance level at the motor end.

4.3.14 Differential mode voltage requirements

The filter link or filter of the converter should be designed to match the differential mode voltage tolerance level at the motor end.

4.3.15 Du/dt requirements

The converter should be designed with filtering links or filters to match the tolerance level of the motor end to du/dt.

4.3.16 Efficiency

Under rated operating conditions, the converter efficiency should not be less than 97%.

4.3.17 Redundancy

The converter shall have redundant functions. It is advisable to use redundant components. power supply, converter control unit.

The converter should have strong fault-tolerant operation capability, and redundancy should be adopted to reduce the impact of a single fault on the entire system.

4.3.18 Stability running time

The continuous operation time of the converter at full load shall not be less than 72 h.

4.3.19 EMC performance

4.3.19.1 Electrostatic discharge immunity

The converter should be able to withstand the rigorous electrostatic discharge immunity test specified in Chapter 5 of GB/T 12668.3-2012.

4.3.19.2 Electrical fast transient pulse group immunity

The converter shall be able to withstand the severe electrical fast transient pulse group immunity test specified in Chapter 5 of GB/T 12668.3-2012.

4.3.20 Total harmonic distortion (THD)

It shall meet the requirements of 7.4 on harmonics in GB/T 20320-2013.

4.3.21 Grid adaptability

It should meet the requirements of GB/T 19963, and negotiate with the manufacturer if it exceeds this condition.

4.3.22 Fault ride-through capability

When a low/high voltage fault occurs, the converter should be coordinated with the main control system of the unit within the specified voltage amplitude and duration.

To ensure that the unit does not run off the grid, it should meet the requirements of NB/T 31051 and NB/T 31111.

4.3.23 Low temperature performance