NB/T 10220-2019Structural design specification for electrical control equipment of plateau wind turbines (English PDF)

3.1 Electrical control assemblies

It is mainly used to control the switching equipment of the power receiving equipment and the combination of the control, measurement, protection and regulation equipment associated with it.

Called. It also refers to the combination of these electrical appliances and the associated internal connecting wires, auxiliary parts, housing and supporting members. [GB/T 3797-2016, definition 3.1].

3.2 Degree of protection

In accordance with the inspection method specified in the standard, determine the protection provided by the enclosure against people approaching dangerous parts and preventing solid foreign objects from entering or water entering. Degree of protection. [GB/T 4208-2017, definition 3.3].

4.1 Environmental conditions parameters

In addition to the environmental condition parameters in accordance with GB/T 31140, other operating environment requirements are as follows.

a) Corrosion grade and durability. C3-high and above, see Appendix A;

b) Pollution degree. Level 3 and above, see Article 7.1.3 in GB/T 7251.1-2013;

c) Overvoltage category. Category IV, see Article 4.3.3.2.2 in GB/T 16935.1-2008;

d) When there are special requirements, such as molds, fungi, and animals that are harmful to the product, the supplier and the buyer shall negotiate by themselves.

6.1 Design and process technical requirements

6.1.1 Cabinet

The cabinet design and process requirements are as follows.

a) The form of the cabinet can be a box type welded cabinet or a frame type cabinet;

b) The protection level of the cabinet with forced air cooling, liquid cooling and natural cooling is not less than IP54.For forced air cooling The dust-proof net of the cabinet should be convenient for regular cleaning and replacement;

c) If the cabinet is composed of parts with different protection levels, the complete set of equipment manufacturers should separately mark the protection levels of different parts;

d) The cabinet should have sufficient strength and rigidity as well as the ability to withstand vibration and impact to meet the requirements of the equipment, components, The installation, commissioning and operation requirements of the wiring and its accessories can meet the requirements of cabinet combining of complete sets of equipment, and meet the requirements of transportation and hoisting;

e) The cabinet body should be designed with safe and reliable fixed installation holes and lifting installation holes according to the carrying capacity, and enter according to GB/T 22764.5 Perform no-load lifting and stiffness characteristic test. After the test, no deformation or damage of parts that affect the fit or function is allowed;

f) The cabinet shall be subjected to vibration and shock tests in accordance with GB/T 18663.1. After the test, the parts shall not be allowed to affect the shape, fit or Functional deformation or destruction.

g) The combination form and external dimensions of the cabinet should consider the possibility of maintenance, disassembly and replacement during the whole life cycle, and it should be in advance Fully evaluate the space constraints of the hub, nacelle, and tower;

h) The independent shell, frame, front door, back panel, top cover, mounting plate, door lock and other metal structural parts of the cabinet shall pass Direct mutual effective connection or mutual effective connection completed by the protective conductor to ensure the continuity of the circuit;

i) The cabinets that realize conductive interconnection should be equipped with safety grounding points or safety grounding terminals, and there should be obvious protective grounding signs;

j) The resistance between the exposed conductive part of the cabinet and the protective grounding point should not be greater than 1ohm, and the contact resistance of each connection point should not Greater than 0.1ohm;

k) Cabinet doors and other movable parts should be opened and closed flexibly, door locks should be reliable, and the coating or plating should not be damaged during the opening and closing process.

The opening angle of the door should not be less than 90 degrees, and the door limit mechanism should be set if necessary;

l) The structure should prevent the gap caused by the stress and deformation of the door and affect the sealing performance;

m) The anti-corrosion grade of cabinet door locks and hinges and other accessories is not lower than the cabinet anti-corrosion grade; when the door lock is set outside the sealing strip, the door lock The protection level can be lower than the cabinet protection level. When the door lock is installed in the door sealing strip, the door lock protection level shall not be lower than the cabinet protection level. Body protection level;

n) The joints of the sealing strips between the cabinets of the combined cabinets should be under the water flow, and glued and smoothed to prevent water seepage;

o) Sealant should be applied to the welded joints of the welding cabinet.

6.1.2 Metal structural parts outside and inside the cabinet

The design and process requirements are as follows.

a) The hoisting beams, cabinet bases, beams, supports, etc. outside the cabinet should be made of profile or sheet metal bending;

b) At the beginning of the design of the load-bearing parts, load simulation should be carried out according to the load and force condition, or use the verified Structural parts of the same type;

c) Minimize the use of welding structures. Welding structures are inevitable. The welding should be firm and uniform. There should be no false welding, pores, cracks, For defects such as weld penetration, gaps, undercuts, arc craters, scratches, etc., the hot-dip galvanized parts shall be fully welded;

d) Assembled parts of different types of metal materials cannot be treated together in solution, spraying or after electrochemical treatment should be used as much as possible Make a combination

e) When two metals (or plating) are in contact, use two metal contacts with similar potentials;

f) The potential difference between the two metals (or plating) inside the cabinet should not exceed 0.5V at most;

g) The potential difference between the two metals (or plating) outside the cabinet should not exceed 0.25V;

h) When two metals (or plating) that are not allowed to contact are in contact, use plating or coating to reduce the potential difference, or add The method of compatible metal gaskets should be adjusted to meet the requirements of f) and g) for potential difference;

i) The edges of all parts and openings should be flat and smooth, flash burrs should be removed, sharp edges should be blunt, and the edges should be rounded as far as possible, half rounded The diameter is at least 0.8mm;

j) For electroplating and oxidizing parts, avoid deep recesses, blind holes and water accumulation structures, and reserve overflow holes for plating solution and gas where there is a ring profile;

Prevent the accumulation of corrosive liquid and it is difficult to remove;

k) Try to avoid the joint structure to prevent the storage of corrosive liquid; seal the inevitable welds and riveting gaps with sealant;

l) The overall design of the structure should be conducive to surface treatment, painting, inspection and maintenance;

m) The design should be as simple as possible, avoid being too complicated, and be easy to install and disassemble;

n) Avoid corrosion caused by design stress, processing and assembly stress;

6.1.3 Copper bar structure

The design and process requirements are as follows.

a) The lap and installation of copper bars meet the requirements of GB 50149;

b) On the premise of satisfying the current carrying capacity, the copper busbar shall give a design margin, and try to use common specifications copper busbar;

c) Copper bars are the main conductors of electrical control equipment. In addition to meeting electrical performance, the structure design and processing also need to consider such as The following factors.

1) When an AC circuit passes through a metal frame forming a closed magnetic circuit, the three-phase copper bar should pass through the same frame hole;

2) There should be no cracks in the bend of the copper bar, and no defects such as indentations, pits, burrs, etc. on the surface;

3) A gap of more than 3mm must be maintained between the steel washer and the steel washer on the copper bar to prevent the closed magnetic circuit formed by the steel nail vortex;

4) The copper bars should have sufficient mechanical strength, and the insulation support spacing of the busbars is shown in Table 1;

5) When the copper bar is too long, in order to make the copper bar have expansion and contraction margin in the longitudinal direction, expansion and contraction compensation should be set in the appropriate part of the bus bar. Joint

6) The connecting hole of the copper bar is generally a round hole, only the longer copper bar is directly fixed on the supporting insulator with bolts Or other special circumstances, long round holes are allowed;

7) To avoid arc discharge, the ends of the copper bars between two adjacent items are rounded.

6.2 Calculation of clearance and creepage distance

6.2.1 General

According to Article 8.3.1 of GB/T 7251.1-2013, electrical clearance and creepage distance are applicable to phase-to-phase and relatively neutral lines; except for conductors Direct grounding is also suitable for relative ground and neutral to ground. For bare live conductors and terminals (e.g., busbars, devices and cable joints Connection) The electrical clearance and creepage distance should at least comply with the relevant regulations of the equipment directly connected to it. When the clearance and creepage distance When the parameter requirements of 6.2.2 a) and b) cannot be met, insulation protection treatment is required.

For the electrical clearance and creepage distance involved in withdrawable structural parts, manufacturing tolerances and dimensions due to wear should be considered For changes, see Article 8.3.2 of GB/T 7251.12-2013.

6.2.2 Electrical clearance

The electrical clearance design requirements are as follows.

a) To determine the rated impulse withstand voltage, the overvoltage category is Category IV, according to Appendix G of GB/T 7251.1-2013, which is determined by the nominal voltage To determine the rated impulse withstand voltage of the equipment, see Appendix C, Table C.1;

b) Determine the correction factor of the rated impulse withstand voltage according to the altitude, in accordance with Article 5.5.1 of GB/T 20626.1-2017, in the product When the operating altitude is different from the test altitude, the power frequency withstand voltage and impulse withstand voltage are corrected according to the altitude where the product is installed. The correction factor is shown in Appendix C, Table C.2;

c) The determination of the electrical clearance from sea level to 2000 m above sea level is based on Article 8.3.2 of GB 7251.1-2013.

The minimum electrical clearance from the plane to 2 000 m. Considering that the circuit should be able to withstand temporary overvoltage and transient overvoltage, shock is recommended The voltage is determined by a value higher than the rated impulse withstand voltage determined by the basic insulation. The highest altitude from sea level to 2 000 m See Appendix C, Table C.3 for small electrical clearance;

d) The clearance of electrical control equipment of the prototype wind turbine generator set with air as the insulating medium is in accordance with GB/T 20626.1-2017 Article 5.2 The clearance correction factor shall be corrected.

See Appendix C, Table C.4, and the revised minimum electrical clearance of high altitude electrical control equipment is shown in Table 2.

6.2.3 Creepage distance

The design requirements for creepage distance are as follows.

a) The rated insulation voltage is selected from the nominal voltage, according to Article 4.3.2.2 of GB/T 16935.1-2008, Table F.3a and Table F.3b, See Table 3;

b) According to Article 8.3.3 of GB/T 7251.1-2013 and Table 2, the altitude from sea level to 2 000 m is determined by the rated insulation voltage The minimum creepage distance for electrical control equipment is 3, the material group is classified as Class III, and the altitude ranges from sea level to 2 000 m The minimum creepage distance is shown in Table 3;

c) The minimum creepage distance is determined at an altitude of 2000 m to 4000 m, and the standard does not specify a correction system for high altitude creepage distance.

The minimum creepage distance is required to be no lower than the electrical clearance. See Table 3.

A.1 Corrosion levels of atmospheric environment and typical environment examples

The atmospheric environment corrosiveness classification can be divided into 6 levels. The classification definition and corresponding durability levels are shown in Table A.1.

B.1 The influence of plateau environment on the structural parts of electrical control equipment

The most obvious impact of the plateau environment on the structural parts of electrical control equipment is that as the altitude increases, the air density decreases, and the device Insulation capacity decreases, electrical clearance and creepage distance need to be increased, and structural design needs to be checked and adjusted;

The range and rate of change of the air temperature in the plateau environment will exceed that of the ordinary land environment. If the temperature difference between day and night is too large, it is easy to produce condensation and make Reduced insulation performance will also deform and crack parts and deform plastic materials. Low relative humidity can easily lead to plastics, etc. The insulating material is deformed or cracked.

Changes in the humidity of the plateau environment, condensation, reasonable selection of materials, design and protection, improve product environmental adaptability. Affect electrical control equipment The factors of preparation materials and structural performance are shown in Table B.1.

C.1 Rated impulse withstand voltage

The clearance should be determined according to the rated impulse withstand voltage, and the rated impulse withstand voltage of the equipment is determined by the nominal voltage, see Table C.1.

C.2 Altitude correction factor for power frequency withstand voltage and impulse withstand voltage

When the product use altitude is different from the test altitude, the power frequency withstand voltage and impulse withstand voltage are corrected according to the altitude where the product is installed. The correction factor is shown in Table C.2.

Note 1. In the routine test focusing on the assessment of internal insulation quality, according to the relevant product standards, the test voltage is the product's resistance at an altitude of 1000m or 2000m. The received voltage value will not be corrected.

Note 2. The test voltage value is the product of the value specified in the standard of the conventional product and the altitude correction factor Ka.

Note 3. If the altitude exceeds 3500m, this table is only for reference, especially for ultra-high voltage and ultra-high voltage equipment.

C.3 Minimum electrical clearance from sea level to 2 000 m above sea level

According to Article 8.3.2 of GB/T 7251.1-2013, determine the minimum electrical clearance from sea level to 2 000 m above sea level, see Table C.3.

C.4 Clearance correction factor

According to the altitude, determine the correction factor, see Table C.4 for the clearance correction factor.

D.1 Common rubber material characteristics

The main characteristics, working temperature and main uses of rubber are shown in Table D.1.