Power cascade high-voltage frequency converter unit active load test system and method based on pcs

Abstract

The present application relates to a system and method for testing the active load of a cascaded high-voltage frequency converter unit based on a PCS, comprising a cascaded high-voltage frequency converter unit to be tested, a filter reactance, a controllable rectifier unit, a PCS device; the rectifier side of the cascaded high-voltage frequency converter unit to be tested is connected to the grid voltage, and the inverter side is connected to the controllable rectifier unit through the filter reactance; the controllable rectifier unit is connected to the positive and negative bus of the PCS device; and the PCS device is connected to the grid. The present application can test the rated power temperature rise, the overload temperature rise, the over-temperature protection, and the feedback function temperature rise of the cascaded high-voltage frequency converter unit. In addition, the temperature rise test data of different currents can be compared, and the thermal simulation data can be compared at the same time to perfect and optimize the thermal simulation data platform, optimize the product design, and improve the product reliability.

Description

Technical Field

[0001] This invention belongs to the field of frequency converter testing technology, specifically relating to a system and method for active power load testing of cascaded high-voltage frequency converter units based on PCS. Background Technology

[0002] High-voltage frequency converters, as an important energy-saving product for achieving the national "dual carbon" target, have been widely used in motor commissioning and precision control in various industries such as power plants, petroleum, chemical, coal, and cement. As the core component of cascaded high-voltage frequency converters, the power unit's temperature rise test after product development is a key indicator for verifying product success.

[0003] The traditional method for testing the temperature rise of the power unit of a cascaded high-voltage frequency converter is to perform reactive power testing with reactors, which only tests the temperature rise of the inverter section and cannot perform active power testing. It also cannot test the temperature rise of the rectifier section, making it impossible to comprehensively assess reliability. When applied to the market, this results in problems with excessive temperature rise of the entire unit, reducing product reliability and affecting the market. At the same time, it is also impossible to perform feedback testing on high-voltage four-quadrant frequency converters. Summary of the Invention

[0004] To address the aforementioned shortcomings of existing technologies, this invention provides a test platform based on PCS, and offers a test method for active power load and a feedback test method. Specifically, it is a PCS-based active power load test system and method for cascaded high-voltage frequency converter units, in order to solve the aforementioned technical problems.

[0005] A PCS-based active power load testing system for cascaded high-voltage frequency converter units includes the cascaded high-voltage frequency converter unit under test, a filter reactor, a controlled rectifier unit, and a PCS device. The rectifier side of the cascaded high-voltage frequency converter unit under test is connected to the main grid voltage via a transformer, and the inverter side is connected to the controlled rectifier unit via a filter reactor. The controlled rectifier unit is connected to the positive and negative buses of the PCS device. The AC power of the PCS device is connected to the main grid via a transformer. The cascaded high-voltage frequency converter unit under test and the PCS device share the same transformer.

[0006] The main grid voltage is connected to the phase-shifting transformer via a knife switch, a first contactor, and a second contactor connected in series. A buffer resistor is connected in parallel with the second contactor. This buffer resistor effectively suppresses the inrush current between the PCS device and the four-quadrant frequency converter.

[0007] The cascaded high-voltage frequency converter unit under test receives a 690V step-down input grid voltage on the rectifier side and outputs single-phase AC power on the inverter side. This single-phase AC power is filtered by a filter reactor and then rectified into DC power by a controllable rectifier unit. The DC power is connected to the positive and negative buses of the PCS device. The output of the PCS device is connected to the grid. The PCS device is set to operate in discharge mode. The test system ultimately feeds back to the grid through the PCS device, and then back to the cascaded high-voltage frequency converter unit under test, thus forming an energy self-circulation and achieving active power load temperature rise testing of the cascaded high-voltage frequency converter unit under test.

[0008] Furthermore, the cascaded high-voltage inverter unit under test is a four-quadrant high-voltage inverter unit. The PCS device is set to operate in charging mode. The PCS device charges the controllable rectifier unit, which then feeds the energy back to the cascaded high-voltage inverter unit under test. The cascaded high-voltage inverter unit under test feeds the energy back to the grid, and then back to the PCS device, forming an energy self-circulation. This enables the testing of the feedback function and temperature rise of the cascaded high-voltage inverter unit under test. The PCS device can only be set to operate in charging mode when the cascaded high-voltage inverter unit under test is a four-quadrant high-voltage inverter unit.

[0009] Furthermore, the current of the cascaded high-voltage frequency converter unit under test is controlled by adjusting the current of the PCS device; rated power temperature rise test, overload temperature rise test, and over-temperature protection test are performed on the cascaded high-voltage frequency converter unit under test.

[0010] When the PCS device is operating in discharge mode, the test method for the active power load test system of a two-quadrant cascaded high-voltage frequency converter unit based on the PCS includes the following steps:

[0011] Step 1: The cascaded high-voltage frequency converter unit under test and the PCS device are simultaneously powered on for buffering. The cascaded high-voltage frequency converter unit under test is a two-quadrant high-voltage frequency converter.

[0012] Step 2: Power on and close the circuit breaker of the PCS device;

[0013] Step 3: Set the PCS device to discharge mode;

[0014] Step 4: Set the target voltage value of the PCS device to the set value and power on;

[0015] Step 5: Set the power factor, voltage angle, and voltage coefficient of the PCS device. After powering on and stabilizing the output at a fixed frequency, continuously adjust the voltage coefficient to adjust the voltage magnitude, and thus the current magnitude. After determining the voltage coefficient, adjust the voltage angle to adjust the current magnitude.

[0016] Step 6: Measure the temperature rise of the cascaded high-voltage frequency converter unit under test using a temperature rise testing device.

[0017] Furthermore, the temperature rise testing device can be a thermocouple or a thermistor.

[0018] When the PCS device is operating in charging mode, the test method for the active power load test system of the four-quadrant cascaded high-voltage frequency converter unit based on the PCS includes the following steps:

[0019] Step 1: The cascaded high-voltage frequency converter unit under test and the PCS device are simultaneously powered on for buffering. The cascaded high-voltage frequency converter unit under test is a two-quadrant high-voltage frequency converter.

[0020] Step 2: Power on and close the circuit breaker of the PCS device;

[0021] Step 3: Set the PCS device to charging mode;

[0022] Step 4: Set the target voltage value of the PCS device to the set value and power on;

[0023] Step 5: Set the power factor, voltage angle, and voltage coefficient of the PCS device. After powering on and stabilizing the output at a fixed frequency, continuously adjust the voltage coefficient to adjust the voltage magnitude, and thus the current magnitude. After determining the voltage coefficient, adjust the voltage angle to adjust the current magnitude.

[0024] Step 6: Measure the temperature rise of the cascaded high-voltage frequency converter unit under test using a temperature rise testing device.

[0025] Furthermore, in step five, the power factor of the PCS device is set to 0.8, the voltage angle to 1 degree, and the adjustment voltage coefficient to 0%. The power-on output is stabilized at 50 Hz. The adjustment voltage coefficient is continuously adjusted to adjust the voltage magnitude, and thus the current magnitude. If the adjustment voltage coefficient is fixed, for example, if the voltage coefficient has been adjusted to 100%, the current still needs to be adjusted. The voltage angle can be adjusted to further increase the current.

[0026] In this invention, the active current of the cascaded high-voltage frequency converter unit under test can be arbitrarily controlled by adjusting the parameters of the PCS device.

[0027] With adjustable active current, it can perform temperature rise tests on cascaded high-voltage frequency converter units of different specifications and compare temperature rise test data under different currents; at the same time, it can compare with thermal simulation data to improve and optimize the thermal simulation data platform, optimize product design, and improve product reliability.

[0028] In addition, the cascaded high-voltage frequency converter unit under test is independent of the test platform and can be replaced at any time, making replacement simple and convenient.

[0029] The beneficial effects of this invention are that it can perform rated power temperature rise tests, overload temperature rise tests, and over-temperature protection tests on cascaded high-voltage frequency converter units, as well as feedback function temperature rise tests; in addition, it can compare temperature rise test data at different currents; and at the same time, it can compare with thermal simulation data to improve and optimize the thermal simulation data platform, optimize product design, and improve product reliability. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a block diagram of the test system of the present invention;

[0032] Figure 2 This is the circuit schematic diagram of the present invention;

[0033] Figure 3 This is the control logic diagram of the PCS device of the present invention in discharge mode;

[0034] Figure 4 This is a control logic diagram of the PCS device of the present invention in charging mode. Detailed Implementation

[0035] As shown in the figure, a PCS-based active power load testing system for cascaded high-voltage frequency converter units includes the cascaded high-voltage frequency converter unit under test, a filter reactor, a controllable rectifier unit, and a PCS device. The input voltage to the cascaded high-voltage frequency converter unit is 690V, which is stepped down by a transformer from the main grid voltage. The output terminal outputs single-phase AC power. The single-phase AC power is filtered by the filter reactor and then rectified into DC power by the controllable rectifier unit. The DC power is connected to the positive and negative buses of the PCS device. The output terminal of the PCS device is connected to the main grid. The PCS device is set to operate in discharge mode. The test system ultimately feeds back to the grid through the PCS device and then back to the cascaded high-voltage frequency converter unit under test, thus forming an energy self-circulation and achieving active power load temperature rise testing of the cascaded high-voltage frequency converter unit under test.

[0036] The main grid voltage is connected to the phase-shifting transformer via a knife switch, a first contactor, and a second contactor connected in series. A buffer resistor is connected in parallel with the second contactor. This buffer resistor effectively suppresses the inrush current between the PCS device and the four-quadrant frequency converter.

[0037] Furthermore, the cascaded high-voltage frequency converter unit under test is a four-quadrant high-voltage frequency converter unit. The PCS device is set to operate in charging mode. The PCS device charges the controllable rectifier unit, which then feeds the energy back to the cascaded high-voltage frequency converter unit under test. The cascaded high-voltage frequency converter unit under test feeds the energy back to the grid, and then back to the PCS device, forming an energy self-circulation. This enables the testing of the feedback function and temperature rise of the cascaded high-voltage frequency converter unit under test.

[0038] When the PCS device is operating in discharge mode, the test method for the active power load test system of the cascaded high-voltage frequency converter unit based on the PCS includes the following steps:

[0039] Step 1: The cascaded high-voltage frequency converter unit under test and the PCS device are simultaneously powered on for buffering. The cascaded high-voltage frequency converter unit under test is a two-quadrant high-voltage frequency converter.

[0040] Step 2: Power on and close the circuit breaker of the PCS device;

[0041] Step 3: Set the PCS device to discharge mode;

[0042] Step 4: Set the target voltage value of the PCS device to the set value and power on;

[0043] Step 5: Set the power factor, voltage angle, and voltage coefficient of the PCS device. After powering on and stabilizing the output at a fixed frequency, continuously adjust the voltage coefficient to adjust the voltage magnitude, and thus the current magnitude. After determining the voltage coefficient, adjust the voltage angle to adjust the current magnitude.

[0044] Step 6: Measure the temperature rise of the cascaded high-voltage frequency converter unit under test using a thermocouple or thermistor.

[0045] When the PCS device is operating in charging mode, the test method for the active power load test system of the cascaded high-voltage frequency converter unit based on the PCS includes the following steps:

[0046] Step 1: The cascaded high-voltage frequency converter unit under test and the PCS device are simultaneously powered on for buffering. The cascaded high-voltage frequency converter unit under test is a two-quadrant high-voltage frequency converter.

[0047] Step 2: Power on and close the circuit breaker of the PCS device;

[0048] Step 3: Set the PCS device to charging mode;

[0049] Step 4: Set the target voltage value of the PCS device to the set value and power on;

[0050] Step 5: Set the power factor, voltage angle, and voltage coefficient of the PCS device. After powering on and stabilizing the output at a fixed frequency, continuously adjust the voltage coefficient to adjust the voltage magnitude, and thus the current magnitude. After determining the voltage coefficient, adjust the voltage angle to adjust the current magnitude.

[0051] Step 6: Measure the temperature rise of the cascaded high-voltage frequency converter unit under test using a thermocouple or thermistor.

[0052] Furthermore, in step five, the power factor of the PCS device is set to 0.8, the voltage angle to 1 degree, and the adjustment voltage coefficient to 0%. The output is then stabilized at 50Hz upon startup. The adjustment voltage coefficient is continuously adjusted to regulate the voltage, and consequently, the current. If the adjustment voltage coefficient is fixed, for example, already adjusted to 100%, and the current still needs adjustment, the voltage angle can be adjusted to further increase the current. The current of the cascaded high-voltage frequency converter unit under test is controlled by adjusting the current of the PCS device. Rated power temperature rise test, overload temperature rise test, and over-temperature protection test are then performed on the cascaded high-voltage frequency converter unit under test.

[0053] The above description describes the preferred embodiments of the present invention and the technical principles applied thereto. For those skilled in the art, any obvious changes such as equivalent transformations or simple substitutions based on the technical solutions of the present invention, without departing from the spirit and scope of the present invention, shall fall within the protection scope of the present invention.

Claims

1. A PCS-based active power load testing system for cascaded high-voltage frequency converter units, characterized in that, The system includes a cascaded high-voltage frequency converter unit under test, a filter reactor, a controllable rectifier unit, and a PCS device. The rectifier side of the cascaded high-voltage frequency converter unit under test is connected to the main grid voltage via a transformer, and the inverter side is connected to the controllable rectifier unit via a filter reactor. The controllable rectifier unit is connected to the positive and negative buses of the PCS device. The AC test of the PCS device is connected to the main grid via a transformer. The tested cascaded high-voltage frequency converter unit is a two-quadrant high-voltage frequency converter unit or a four-quadrant high-voltage frequency converter unit; the current of the tested cascaded high-voltage frequency converter unit is controlled by adjusting the current of the PCS device. When the cascaded high-voltage frequency converter unit under test is a two-quadrant high-voltage frequency converter unit, the PCS device is set to work in discharge mode. The test system finally feeds back to the grid through the PCS device and then feeds back to the cascaded high-voltage frequency converter unit under test, thus forming an energy self-circulation, thereby realizing the active load temperature rise test of the cascaded high-voltage frequency converter unit under test. When the cascaded high-voltage frequency converter unit under test is a four-quadrant high-voltage frequency converter unit, the PCS device is set to work in charging mode. The PCS device charges the controllable rectifier unit, and the energy is fed back to the cascaded high-voltage frequency converter unit under test through the controllable rectifier unit. The cascaded high-voltage frequency converter unit under test feeds the energy back to the grid, and then feeds it back to the PCS device, forming an energy self-circulation, thereby realizing the feedback function test and temperature rise test of the cascaded high-voltage frequency converter unit under test.

2. The PCS-based active power load testing system for cascaded high-voltage frequency converter units according to claim 1, characterized in that, The main grid voltage is connected to the transformer via a knife switch, a first contactor, and a second contactor connected in series; the second contactor is connected in parallel with a buffer resistor.

3. The PCS-based active power load testing system for cascaded high-voltage frequency converter units according to claim 1, characterized in that, The current of the cascaded high-voltage frequency converter unit under test is controlled by adjusting the current of the PCS device; rated power temperature rise test, overload temperature rise test, and over-temperature protection test are performed on the cascaded high-voltage frequency converter unit under test.

4. A test method for the PCS-based active power load testing system for cascaded high-voltage frequency converter units as described in claim 1, characterized in that, Includes the following steps: Step 1: The cascaded high-voltage frequency converter unit under test and the PCS device are simultaneously powered on for buffering. The cascaded high-voltage frequency converter unit under test is a two-quadrant high-voltage frequency converter. Step 2: Power on and close the circuit breaker of the PCS device; Step 3: Set the PCS device to discharge mode; Step 4: Set the target voltage value of the PCS device to the set value and turn it on; Step 5: Set the power factor, voltage angle, and voltage coefficient of the PCS device. After powering on and stabilizing the output at a fixed frequency, continuously adjust the voltage coefficient to adjust the voltage magnitude, and thus the current magnitude. After determining the voltage coefficient, adjust the voltage angle to adjust the current magnitude. Step 6: Measure the temperature rise of the cascaded high-voltage frequency converter unit under test using a temperature rise testing device.

5. A test method for the PCS-based active power load testing system for cascaded high-voltage frequency converter units as described in claim 1, characterized in that, Includes the following steps: Step 1: The cascaded high-voltage frequency converter unit under test and the PCS device are powered on and buffered simultaneously. The cascaded high-voltage frequency converter unit under test is a four-quadrant high-voltage frequency converter. Step 2: Power on and close the circuit breaker of the PCS device; Step 3: Set the PCS device to charging mode; Step 4: Set the target voltage value of the PCS device to the set value and power it on; Step 5: Set the power factor, voltage angle, and voltage coefficient of the PCS device. After powering on and stabilizing the output at a fixed frequency, continuously adjust the voltage coefficient to adjust the voltage magnitude, and thus the current magnitude. After determining the voltage coefficient, adjust the voltage angle to adjust the current magnitude. Step 6: Measure the temperature rise of the cascaded high-voltage frequency converter unit under test using a temperature rise testing device.

6. The test method for the active power load test system of a cascaded high-voltage frequency converter unit based on PCS according to claim 4 or 5, characterized in that: In step five, the power factor of the PCS device is set to 0.8, the voltage angle to 1 degree, and the adjustment voltage coefficient to 0%. The power-on output is stabilized at 50 Hz. The adjustment voltage coefficient is continuously adjusted to adjust the voltage and, consequently, the current.

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