DL/T 2033-2019Test methods for power unit of high voltage variable frequency drive used in fossil-fuel power plants (English PDF)

4.1 Composition

The power unit consists of a main circuit and a control circuit. The main circuit should include the input bus, rectifier, DC link, inverter, bypass loop Section, output bus. The control circuit shall include control power circuit, optical fiber communication circuit, instruction calculation circuit, IGB T drive circuit. power the typical structure schematic diagram of the main circuit of the unit is shown in Figure 1.

4.2 Output rated capacity

Under the specified power supply conditions, when outputting rated voltage and rated frequency, the output capacity of the power unit should not be lower than the rated capacity.

5.1 General requirements

Under normal test environment conditions, the ambient temperature range should be 5°C~40°C, the relative humidity range should be 5%~85%, no condensation;

The electrical test conditions should meet the requirements of GB/T 30843.1; there should be safety measures to protect the test personnel.

5.2 Instrumentation

Test instruments, meters, and sensors should be qualified by metrological verification or calibration and within the validity period. The accuracy of electrical measuring instruments should not be lower than for level 0.5 (except megohmmeter), the error of the thermometer should not be greater than ±1°C.

5.3 Test platform

The test of the power unit should be carried out on a test platform equivalent to the actual work. The test platform should be composed of AC electronic loads and external power grids.

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6.1 Test items

6.1.1 The samples should be subjected to type test, factory test and routine test, and the test items should meet the requirements of Table 1.

6.1.2 The test period should be set according to the operating conditions of the equipment. Routine tests should be carried out under one of the following conditions.

a) 3 to 5 years after equipment operation;

b) When the power unit has a serious failure;

c) When the power unit replaces important parts such as control boards;

d) When the high-voltage inverter stops due to frequent failures of the power unit;

e) When the user considers it necessary.

6.2 Parameter check

6.2.1 Diode parameter check

6.2.2 Capacitance parameter verification

Note. For power units with input voltage less than 690V, the reference capacity is calculated according to the inverse linear ratio.

6.2.3 IGB T parameter check

6.2.5 Parameter check of thyristor and contactor

The parameters of thyristor and contactor shall meet the requirements of Table 5.

6.3 Performance test

6.3.1 Insulation test

a) Insulation resistance

b) Insulation voltage the insulation voltage of the main circuit and control circuit shall meet the requirements of Table 7.

c) AC or DC voltage test

6.3.2 Control circuit power-on test

The power-on test of the control circuit should test the voltage regulation range and output ripple coefficient of the regulated power supply.

When testing the voltage stabilization range, the regulated power supply should be connected to the rated load. According to the requirements of the voltage stabilization range, change the input voltage amplitude and measure the output for voltage changes, the deviation between the output voltage and the rated voltage should be less than 5%.

When testing the output ripple factor, the input and output voltages and load currents should be rated values. Measure the peak-to-peak output ripple voltage and output the voltage ripple factor should be less than 2%.

6.3.3 Main circuit power-on test

Under the condition of IGB T blocking, power up the main circuit of the power unit and gradually increase the voltage to the rated value. Record the DC loop under different input voltages Section voltage value, capacitor voltage equalization value, alarm action status.

6.3.4 Protection function test

a) Voltage protection test Voltage protection should include the functions of undervoltage, overvoltage, and input lack of equivalence. The upper limit of the undervoltage protection setting value should be less than 75%Ud, and the overvoltage protection setting value the lower limit should be greater than 125% Ud, and the alarm should be correct when the input phase is missing.

Note. Ud is the rated voltage of the DC bus.

b) Over-temperature protection test Apply an analog over-temperature signal to the over-temperature acquisition end of the power unit control board, and the power unit should alarm correctly.

6.3.5 IGB T drive protection test

a) Drive protection test when IGB T is damaged when the IGB T in the power unit is damaged (IGB T open circuit or short circuit), the IGB T drive should have a protection function. The test principle diagram is shown in Figure 3.

IGB T drive

Control connection fiber Power unit control board test control unit IGB T fault generator

Figure 3 Schematic diagram of drive protection test when IGB T is damaged

b) Drive protection performance test to confirm the performance of the IGB T drive protection in the power unit, the power unit IGB T should be tested according to the test method in GB/T 29332 Double pulse test.

6.3.6 Electromagnetic compatibility test

a) Lowest immunity

The minimum immunity of the power unit shall meet the requirements of Table 9.

6.3.7 Load test

a) Reactive load test Connect the reactor at the output side of the power unit to adjust the output reactive current of the power unit to 110% of the rated output current. IGB T turns off the peak the voltage should be less than 1.4Ud, the electrolytic capacitor ripple voltage should be less than 3.5% Ud, and the electrolytic capacitor ripple voltage should be less than 5.5% Ud.

b) Active load test

Use AC electronic load to perform active load test on the power unit to assess long-term load stability and temperature rise characteristics. Should include rated for load test and overload test, the test standards are implemented in accordance with GB/T 30843.1.The principle diagram of the active load test is shown in Figure 4.

c) Damp heat test (steady state) the damp heat test (steady state) of the power unit shall be performed according to GB/T 2423.3 and GB 12668.501.The test temperature should be (40±2)°C, the relative humidity should be (93±3)%, and the exposure duration should be greater than 24h.

6.4 Test procedure

Refer to Appendix A for the typical procedure of power unit test.

7.1 Writing requirements

a) The test report should include the following.

1) Equipment parameters;

2) Test basis;

3) Test items;

4 Conclusion.

b) The test item should contain the following data.

1) Measured data;

2) The test standard has the required ambient temperature or the temperature of the tested product;

3) The humidity required by the test standard;

4) Test date;

5) The name and model of the test instrument.

7.2 Report template

The test report template can be found in Appendix B.

Appendix A

(Informative appendix) Test typical process A. 1 Scope of application this standard is applicable to the power unit of cascaded high voltage frequency converter. The basic parameters can be determined according to Table A.1.

Table A.2 Test equipment