NB/T 10327-2019Low-voltage active three-phase unbalanced load regulator (English PDF)

3.1 Power supply region

(One) The power supply range or area of the transformer.

3.2 Three-phase current unbalance rate

In a three-phase AC circuit, take the absolute maximum value of the difference between the effective value of the three-phase current and its arithmetic average value, and the ratio to the average value in percentage Number representation. The following formula applies to three-phase three-wire and three-phase four-wire. In three-phase four-wire, there is no need to calculate the neutral current.

3.3 Electronic power conversion

[Electricity] [Electronics] Converter (electronics) (power) conversion.

Commutation With the help of electronic valve devices, one or more characteristics of the power system are changed, and there is basically no considerable loss.

Note: For example, the characteristics are voltage, phase number, and frequency (including zero frequency). [GB/T 2900.33-2004, definition 551-11-02]

3.4 Electronic power converter

[Power] [Electronics] Converter (electronics) (power) converter.

Inverter An operating unit consisting of one or more valve devices, transformer/filter (if necessary) and auxiliary equipment (if any).

Note: The English term "converter" is spelled "converter" and "convertor", both of which are correct. This standard uses "converter". [GB/T 2900.33-2004, definition 551-12-01]

3.5 Rated voltage

The nominal voltage of the device to be connected to the grid.

3.6 Rated current

Under rated conditions, the effective value of the allowable power frequency current when the device works continuously for a long time.

Note: Rewrite DL/T 1216-2013, definition 3.7.

3.7 Rated capacity

Under rated conditions, the reactive power output when the device is running at rated current, in kilovar (kvar).

3.8 No-load operation state

After precharging and pulse width modulation, the DC bus voltage is maintained at a given value, and the device does not output compensation current.

3.9 Rated loss

Under rated voltage, when the device output is rated current, the active power measured at its input.

3.10 Control range

The maximum variation range of the controllable output electrical quantity provided by the device at the connection point of the device and the AC system. [DL/T 1193-2012, definition 3.5.2]

3.11 Step response time

When the step control signal is input, the time it takes for the output electrical quantity of the device to reach 90% of the target value from 0 to the target value, and there is no Overshoot. see picture 1. [DL/T 1193-2012, definition 3.5.14]

5.1 Normal use conditions

5.1.1 Ambient air temperature

The ambient air temperature should not exceed +40 °C, and its average temperature within 24 h should not exceed +35 °C;

5.1.2 Relative humidity

The ambient air temperature is 30 °C, and the relative humidity is not more than 93%.

5.1.3 Contamination level

The pollution degree does not exceed the c level.

5.1.4 Altitude

The altitude is 2000 m and below.

5.1.5 Anti-seismic level

The horizontal acceleration is not more than 2 m/s²; the vertical acceleration is not more than 1 m/s².

5.1.6 Wind speed

The maximum wind speed at 10 m above the ground does not exceed 35 m/s.

5.1.7 Installation site conditions

The installation site should be free of severe mechanical vibration and impact, no media that can cause fire and explosion hazards, and no corrosion or damage in the surrounding media The gas and conductive medium of the insulation and surface coating layer should be free of harmful gas and steam, and no serious molds are allowed.

The device should not be exposed to strong electric and magnetic fields.

See Appendix B for the electrical conditions of the grid connection points.

5.2 Special conditions of use

If it is used under special conditions that do not comply with 5.1, a special agreement should be signed between the manufacturer and the purchaser.

6.1 Basic circuit

The device is mainly composed of grid-connected switch, lightning arrester, charging resistor, bypass switch, filter unit (connected inductance), converter bridge, DC capacitor It consists of a cooling device, a cooling fan, a control and monitoring system and other equipment. The basic circuit diagram is shown in Figure 3.

Note: The inverter unit is in the dotted frame.

6.2 Technical requirements for component equipment

6.2.1 Grid-connected switch (circuit breaker)

Technical requirements include.

a) Should meet the requirements of GB/T 14048.2;

b) It should have the maximum output current of the switching device and the ability to break short-circuit current;

6.2.2 Lightning arrester

Technical requirements include.

a) The incoming line lightning arrester should use gapless metal oxide arrester;

b) The rated voltage should be the upper limit of the normal operating line voltage with a certain margin;

c) The flow capacity of the arrester should be verified to ensure safe operation;

d) Should meet the requirements of GB/T 11032.

6.2.3 Charging resistance

Technical requirements include.

a) It should be able to limit the charging current of the DC capacitor under the design value when the device is put into use;

b) It should be able to withstand the maximum impact power without any thermal and/or mechanical damage;

c) Should meet the requirements of JB/T 6319.

6.2.4 Bypass switch

6.2.5 Filter unit (connect inductance)

Technical requirements include.

a) The filter unit should be able to limit the high frequency harmonic current below the allowable value;

b) The fundamental reactive power generated by the filter capacitor should not exceed the allowable value;

c) The reactor should meet the requirements of GB/T 1094.6 and GB/T 14860.1;

d) The capacitor should meet the requirements of GB/T 17702. Refer to Appendix C.2 for filter unit parameter selection

6.2.6 Converter bridge

The converter bridge should be designed according to the system operating conditions and performance requirements, including.

a) The converter bridge should be able to withstand the impact of overvoltage and overcurrent caused by system faults and switching operations;

b) When designing the converter bridge, full consideration should be given to reducing the possible adverse effects of the distributed parameters of power electronic devices, and appropriate margins should be considered. degree;

c) The converter bridge should have the ability to prevent false triggering or tolerate false triggering;

d) Should meet the requirements of GB/T 3859.1.

6.2.7 DC capacitor

Technical requirements include.

a) It should be able to meet the requirements of device capacity;

b) It should be able to limit the DC voltage fluctuation range within the allowable value;

c) Should meet the requirements of GB/T 17702.

Refer to Appendix C.3 for parameter selection of DC capacitor bank

6.2.8 Cooling fan

The cooling fan should have sufficient heat dissipation capacity, and the protection level of the device, the influence of the installation location, and the cooling of the inverter unit should be considered. But the way matches.

6.2.9 Control and monitoring system

Technical requirements include.

a) The control function can include the following options.

1) Compensation for three-phase unbalanced current;

2) Compensation of reactive current;

3) Compensation of harmonic currents;

4) Comprehensive compensation.

b) The monitoring system should have fault protection function;

c) The device should be equipped with a wireless communication module, which can realize information interaction and remote control with mobile terminals;

d) The device should be able to ensure that data will not be lost after power failure;

e) The device should have the necessary logic interlock function to prevent misoperation.

6.2.10 Other equipment requirements

Other equipment (such as isolation switches, fuses, current transformers, voltage transformers, etc.) refer to the requirements of the corresponding national standards, such as.

a) Refer to GB/T 14048.3 for isolating switch;

b) Refer to GB/T 13539.1 for fuses;

c) Refer to GB/T 20840.1 and GB/T 20840.2 for current transformers, and outdoor opening and closing equipment should be adopted;

d) Refer to GB/T 20840.1 and GB/T 20840.3 for voltage transformer.

7.1 Appearance and structure

The device structure and external dimensions are reasonable in design, suitable for single-pole or double-pole fixing, which is convenient for installation, inspection and maintenance.

The device shell should be made of 2 mm thick stainless steel plate, which should be able to withstand the electric power and thermal stress that may be generated when the device is short-circuited. Meet the mechanical strength requirements during handling, installation and operation.

The device should be equipped with lifting lugs for carrying, and equipped with locks to prevent rain, door shafts to prevent rust, and to prevent scratches and water ingress.

The welded parts of the device should be welded firmly, and the welds should be uniform and beautiful, without weld penetration, cracks, undercuts, residues, pores, etc.

There should be no rust or other mechanical damage on the surface of all metal parts of the device, and there should be a reliable anti-corrosion layer.

The door of the device should be able to open and close flexibly within an angle of not less than 90°.

The nameplate parameters are clearly marked and the data is correct.

7.2 Selection and installation of components and accessories

All independent electrical components and accessories installed in the device shall comply with 6.2 of this standard and the relevant standards of components, and shall be in accordance with the manufacturer's instructions. The book is installed.

The arrangement of electrical components should be neat, correct, easy to install, wire, repair and replace.

Components that need to be operated, adjusted and reset inside the device should be easy to operate.

The colors of the indicator lights and buttons selected in the device should meet the requirements of GB/T 4025.

The phase sequence arrangement of the busbar is viewed from the front of the device, and the phase sequence identification and arrangement should generally meet the requirements of Table 2.

The long-term allowable current of the main circuit bus should not be less than 1.5 times the rated current; the connection of the bus should be firm and should not shake freely, and the wiring should be Neat and beautiful; the rated voltage of the bus bar shall not be lower than the rated working voltage of the corresponding circuit; the auxiliary circuit wire should have a cross-sectional area not less than 1.5 mm² The copper core multi-strand insulated wire; the cross-sectional area of the wire of the current measurement loop should not be less than 2.5 mm², and the wire should be connected by cold crimping end.

The bus bars and insulated wires in the device should have an insulation level compatible with the rated working voltage.

The material, connection and arrangement method of the bus bar and the insulating support should have the electric power and thermal stress that may be generated when the device is short-circuited. Power capacity.

7.3 Safety and protection

7.3.1 Degree of protection

The protection level of the device shell shall not be lower than IP43.

7.3.2 Safety signs

The device should clearly define relevant warning signs and symbols in accordance with the requirements of GB 2894 and its components.

7.3.3 Protection and grounding

The protection against direct contact can rely on the structural measures of the device itself, or on the additional measures taken during the installation of the device. The manufacturer shall provide relevant information in the installation manual.

The protection of indirect contact should be made by the protective circuit in the device. The protective circuit can be realized by installing a protective conductor separately, or it can be used The structural components of the device (such as housing, frame) are implemented.

Metal shells that are in direct contact, metal parts that may be charged, and metal bases of electrical components that require grounding (including possible insulation damage There should be a reliable electrical connection between the door, board, bracket and the main ground, which can be electrically connected to the main ground.

The resistance value between the points should not be greater than 0.1 ohm.

All components of the protection circuit in the device should be able to withstand the maximum thermal stress and electrical stress that the device may encounter at the installation site.

The color of the protective conductor should be yellow-green, and yellow-green should not be used for other purposes except as the identification color of the protective conductor.

The diameter of the grounding terminal shall not be less than phi 10 mm, and shall be clearly marked.

The DC side of the device should be equipped with a discharge resistor. After the power is cut off, the DC side capacitor should drop to a safe voltage within the specified time. The capacitor is not discharged Before contact will cause danger, warning signs or safety instructions should be installed.

The cross-sectional area of the protective conductor (PE) should not be less than the value given in Table 2. When the neutral conductor (N) current does not exceed 30% of the phase current, the table 2 It can also be used to protect neutral conductors (PEN). The minimum cross-sectional area of copper PEN conductors should be 10 mm².

Note: If the wire selected according to Table 2 is not a standard size, the closest protective conductor with a larger standard cross-sectional area should be used. When phase conductor and protective conductor When the materials are different, corrections should be made to achieve the conductive effect of the same material. The minimum cross-sectional area of the protective conductor should not be less than 2.5 mm².

7.4 Clearance and creepage distance

The electrical clearance and creepage distance of each component in the device should meet the requirements of the respective standards.

Under normal conditions of use, the electrical gaps between exposed live objects of different polarities or phases in the device and between them and the housing and ground The creepage distance shall not be less than that specified in Table 3.

7.5 Insulation level of the device

7.5.1 Insulation resistance verification

Use insulation measuring instruments with a voltage not less than 500 V to measure insulation resistance.

The insulation resistance between live parts, between live parts and bare conductive parts, and between live parts and the ground shall not be less than the power frequency withstand voltage value × 103 ohm.

7.5.2 Power frequency withstand test voltage

The main circuit and the auxiliary circuit directly connected to the main circuit should be able to withstand the power frequency withstand test voltage specified in Table 5.

7.6 Protection and alarm function

7.6.1 Protection function

The device should generally have the following protection functions.

1) DC side over-voltage and under-voltage protection, output should be blocked during operation; […]