No-load voltage boosting test method and system for CLCC converter

Abstract

The present invention discloses a no-load voltage application test method and system for a CLCC converter, including selecting the positive / negative pole in a bipolar system as the test pole, independently controlling the test pole, putting a preset protection device into operation and starting the no-load voltage application test device, adjusting the DC voltage according to the firing angle. When the first test mode starting condition is satisfied, the converter valve enters the first mode and keeps the firing angle unchanged within a set first time period. After keeping the firing angle unchanged within the set time period, continue to adjust the firing angle to make the DC voltage value of the test pole change at a set change rate. When the second test mode starting condition is satisfied, the converter valve enters the second mode and keeps the firing angle unchanged within the set time period to complete the no-load voltage application test; after the test is completed, reduce the output voltage of the no-load voltage application test device until the voltage drops to zero and automatically locks the test pole. The present invention has prominent advantages such as low cost and high reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic converters, and particularly to a no-load voltage application test method and system for a CLCC converter. Background Art

[0002] The high-voltage direct current open-circuit test (open line test, OLT), also known as the no-load voltage application test, is a basic test that must be carried out before the commissioning of a UHV DC transmission system or a high-voltage DC transmission system. The main functions of this test include checking the insulation performance and voltage withstand performance of high-voltage DC equipment and lines after a long-term outage or maintenance, checking the turn-on and turn-off capabilities of the converter valves, checking whether the functions of the DC control system software and hardware are normal, such as whether the trigger optical fibers are normal and whether the trigger timing sequence is correct, checking whether the protection system operates normally, that is, being able to correctly respond to the DC control system under set conditions, and checking whether the DC transmission circuit is normal. The OLT test avoids the start-up of the DC pole when there is a ground fault in the line, thereby improving the reliability and stability of the system.

[0003] See the appendix Figure 1 , which is a schematic diagram of the current conduction path in the CLCC operation mode. The light-colored path is the current conduction path in the CLCC operation mode. Under the rated operating conditions of the CLCC operation mode, the IGBT unit and the main-branch thyristor valve are triggered and conducted simultaneously, and the conduction path of the low-voltage IGBT valve in the conduction state; see the appendix Figure 2 , which is a schematic diagram of the current conduction path in the LCC operation mode. The light-colored path is the current conduction path in the LCC operation mode. When the low-voltage IGBT valve does not meet the requirements of the CLCC operation mode, such as when the redundant quantity of IGBTs is reduced to the project-specified value, or when power reverse transmission is required, the IGBT series unit can be blocked, and the bypass thyristor series unit can be triggered to make the converter operate in the LCC mode. In addition, when the DC system needs to perform power reverse transmission, the converter will change from the inverter operation condition to the rectifier operation condition. At this time, the system short-circuit current will be much larger than that in the inverter condition, and the operation condition of the converter also needs to be changed to the LCC state. The bypass thyristor series unit is directly composed of several high-voltage high-power thyristors connected in series.

[0004] Therefore, when performing the OLT test on the CLCC converter currently, the OLT test for each pole needs to be carried out twice. Once in the LCC mode to complete the no-load voltage application to the thyristors, and once in the CLCC mode to complete the no-load voltage application to the IGBTs. Conducting the test twice for each pole takes a long time and may cause hazards such as insulation aging and equipment damage.

[0005] CN114460397A discloses a no-load voltage boosting test system and method applicable to a voltage source converter. The system includes a test control device and a DC control and protection device connected to each other. The test control device is used to perform a no-load voltage boosting test, and the no-load voltage boosting test includes an uncontrolled charging stage, a controllable charging stage, a DC voltage boosting stage, and a steady state stage. The DC control and protection device is optimized for the DC voltage boosting stage, and dynamically adjusts the number of sub-modules input to the upper and lower bridge arms of the voltage source converter in real time. The invention targets a voltage source, which is actually different from the present invention, and requires a high cost for multiple upper and lower bridge arm sub-modules. Summary of the Invention

[0006] To solve the deficiencies such as high cost and long time consumption in the prior art, the present invention provides a no-load voltage boosting test method and system for a CLCC converter.

[0007] The present invention adopts the following technical solutions.

[0008] On the one hand, the present invention discloses a no-load voltage boosting test method for a CLCC converter, including:

[0009] Select the positive or negative pole as the test pole in the bipolar system and independently control the test pole;

[0010] Put the preset protection device into operation, then start the no-load voltage boosting test device, and load the output DC voltage to the corresponding test pole of the CLCC converter;

[0011] Adjust the trigger angles of the thyristors of the CLCC converter according to the set first trigger angle command value, so as to adjust the DC voltage. When the first test mode start condition is met, the commutation valve enters the first mode of the CLCC converter and keeps the trigger angle command value unchanged within the set first time period;

[0012] After keeping the trigger angle command value unchanged within the set first time period, continue to adjust the trigger angle to make the DC voltage value of the test pole change at the set change rate. When the second test mode start condition is met, the commutation valve enters the second mode of the CLCC converter and keeps the trigger angle command value unchanged within the set second time period, thus completing the no-load voltage boosting test;

[0013] After the test is completed, reduce the output voltage of the no-load voltage boosting test device at the set rate until the voltage drops to zero, and automatically lock the test pole.

[0014] Further preferably,

[0015] The preset protection device includes an overcurrent protection device, an overvoltage protection device, a differential protection device, and a ground protection device.

[0016] Further preferably,

[0017] The first trigger angle command value is set according to the following formula:

[0018] ;

[0019] where k represents the k-th sampling point; is the trigger angle command value at the k-th sampling point; is the initial test value of the trigger angle; is the correlation coefficient related to the DC voltage change.

[0020] Further preferably,

[0021] The correlation coefficient related to the DC voltage change is shown in the following formula:

[0022] ;

[0023] where, is the voltage adjustment coefficient, is the rated DC voltage of the test pole.

[0024] Further preferably,

[0025] The voltage adjustment coefficient is shown in the following formula:

[0026] ;

[0027] where, is the trigger angle command value at the k-th sampling point, is the trigger angle measurement value at the k-th sampling point.

[0028] Further preferably,

[0029] The starting condition of the first test mode is:

[0030] ;

[0031] where, is the trigger angle command value at the k-th sampling point, is the test mode start coefficient, is the trigger angle measurement value at the k-th sampling point.

[0032] Further preferably,

[0033] The first mode of the CLCC converter is the CLCC mode. After the converter valve enters the CLCC mode, an unloaded voltage application test is performed on the IGBT.

[0034] Further preferably,

[0035] The starting condition of the second test mode is described by the following formula:

[0036] ;

[0037] wherein, is the DC voltage at the k-th sampling point, is the test mode start coefficient, is the rated DC voltage of the test pole.

[0038] Further preferably,

[0039] The second mode of the CLCC converter is the LCC mode. After the converter valve enters the LCC mode, an unloaded voltage application test is performed on the thyristors.

[0040] On the other hand, the present invention discloses an unloaded voltage application test system based on an unloaded voltage application test method, including a test pole control module, a test start module, a first trigger angle adjustment module, a second trigger angle adjustment module, and a test termination module:

[0041] The test pole control module selects the positive / negative pole as the test pole in the bipolar system and performs independent control on the test pole;

[0042] The test start module puts the preset protection device into operation, then starts the unloaded voltage application test device, and loads the output DC voltage to the corresponding test pole of the CLCC converter;

[0043] The first trigger angle adjustment module adjusts the trigger angles of the thyristors of the CLCC converter according to the set first trigger angle command value, thereby adjusting the DC voltage. When the first test mode start condition is met, the converter valve enters the first mode of the CLCC converter and keeps the trigger angle command value unchanged within the set first time period;

[0044] The second trigger angle adjustment module, after the first trigger angle adjustment module finishes running, continues to adjust the trigger angle to make the DC voltage value of the test pole change at the set change rate. When the second test mode start condition is met, the converter valve enters the second mode of the CLCC converter and keeps the trigger angle command value unchanged within the set second time period, thereby completing the unloaded voltage application test;

[0045] The test termination module, after the test is over, reduces the output voltage of the unloaded voltage application test device at the set rate until the voltage drops to zero, and automatically locks the test pole.

[0046] The beneficial effects of the present invention are as follows: compared with the prior art:

[0047] When the present invention performs the OLT test on the CLCC converter, each pole OLT test only needs to be performed once, greatly shortening the time required for the OLT test and reducing the risks of insulation aging, equipment damage, etc.;

[0048] During the OLT test of the present invention, no-load voltage application tests were conducted on IGBTs and thyristors respectively in the CLCC mode and the LCC mode. Therefore, two voltage increases are required. To avoid the problem of inaccurate OLT test results caused by too rapid a change in the trigger angle, i.e., too large a change in the trigger angle, during the first voltage increase process, and unnecessary time consumption caused by too slow a voltage increase process, the present invention proposes a calculation formula for the first trigger angle command value, which not only avoids inaccurate OLT test results but also avoids unnecessary time consumption.

[0049] Since the present invention needs to switch between the CLCC mode and the LCC mode while the voltage is constantly changing, the present invention specifically proposes the first test mode start condition and the second test mode start condition, thereby ensuring the reliability of the present invention and the accuracy of the test results. Description of the Drawings

[0050] Figure 1 is a schematic diagram of the current conduction path of the CLCC converter in the CLCC operating mode;

[0051] Figure 2 is a schematic diagram of the current conduction path of the CLCC converter in the LCC operating mode;

[0052] Figure 3 is a schematic flow diagram of a no-load voltage application test method for a CLCC converter according to the present invention. Detailed Embodiments

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only a part of the embodiments of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0054] This application discloses a no-load voltage application test method for a CLCC converter. Refer to the attached Figure 3 , including:

[0055] Select the positive or negative pole as the test pole in the bipolar system and independently control the test pole;

[0056] Put the preset protection device into operation, then start the no-load voltage application test device, and load the output DC voltage to the corresponding test pole of the CLCC converter;

[0057] The preset protection device includes an overcurrent protection device, an overvoltage protection device, a differential protection device, and a ground protection device.

[0058] Adjust the firing angles of thyristors of the CLCC converter according to the set first firing angle command value, so as to adjust the conduction moments of thyristors, and further adjust the DC voltage.

[0059] Those skilled in the art should know that the DC voltage of the test pole can be changed by adjusting the firing angle. Whether the DC voltage of the test pole is continuously increased, or the DC voltage of the test pole is continuously decreased, or the DC voltage of the test pole is increased and decreased according to the set rules, as long as the set conditions are met and the firing angle remains unchanged within the set time period, the OLT test can be completed; those skilled in the art can adjust the first firing angle command value according to the actual situation; for improving the calculation accuracy, the calculation of the first firing angle command value proposed in the embodiment of the present invention is only a preferred embodiment, and is not an inevitable limitation for implementing a no-load voltage application test method for a CLCC converter of the present invention.

[0060] Those skilled in the art should know that the initial test value of the firing angle is generally 150° - 170°. Therefore, in the preferred embodiment of the present invention, the OLT test is carried out by gradually reducing the firing angle to continuously increase the voltage, thereby further shortening the test time of the OLT test.

[0061] The first firing angle command value is set according to the following formula:

[0062] ;

[0063] where k represents the kth sampling point, that is, the kth first firing angle command value calculation point; is the firing angle command value at the kth sampling point; is the initial test value of the firing angle; is the DC voltage change correlation coefficient. Preferably, the sampling interval is set to 1 second; the sampling interval is the calculation interval.

[0064] The DC voltage change correlation coefficient is shown in the following formula:

[0065] ;

[0066] where is the voltage adjustment coefficient, is the rated DC voltage of the test pole, and its unit is kV.

[0067] The voltage adjustment coefficient is shown in the following formula:

[0068] ;

[0069] where is the firing angle command value at the kth sampling point, is the trigger angle measurement value at the k-th sampling point.

[0070] When the first test mode start condition is met, the converter valve enters the first mode of the CLCC converter and keeps the trigger angle and the trigger angle command value unchanged within a set first time period by pausing the reference value through pole control; the preferred value range of the set first time period is 2.5 to 3.5 minutes.

[0071] The first test mode start condition is:

[0072] ;

[0073] where, is the trigger angle command value at the k-th sampling point, is the test mode start coefficient, is the trigger angle measurement value at the k-th sampling point.

[0074] The first mode of the CLCC converter is the CLCC mode. After the converter valve enters the CLCC mode, an unloaded voltage application test is performed on the IGBT.

[0075] After keeping the trigger angle command value unchanged within the set first time period, continue to adjust the trigger angle to change the DC voltage value of the test pole at a set change rate;

[0076] Those skilled in the art should know how to adjust the trigger angle to increase or decrease the DC voltage value of the test pole at a set frequency; preferably, the change rate of the set DC voltage is 1 kV / s.

[0077] When the second test mode start condition is met, the converter valve enters the second mode of the CLCC converter and keeps the trigger angle command value unchanged within a set second time period, thereby completing the unloaded voltage application test; the preferred value range of the set second time period is 2.5 to 3.5 minutes.

[0078] The second test mode start condition is as described by the following formula:

[0079] ;

[0080] where, is the DC voltage at the k-th sampling point, is the test mode start coefficient, is the rated DC voltage of the test pole.

[0081] The second mode of the CLCC converter is the LCC mode. After the converter valve enters the LCC mode, an unloaded voltage application test is performed on the thyristor.

[0082] After the test is completed, the output voltage of the no-load voltage boosting test device is reduced at a set rate until the voltage drops to zero, and the test pole is automatically locked.

[0083] Embodiment 1

[0084] A no-load voltage boosting test method for a CLCC converter.

[0085] Check whether the test equipment is in good condition. The test equipment includes an OLT test device, IGBTs, thyristors, a DC power supply, an oscilloscope, a preset protection device, etc.

[0086] Select the positive or negative pole in the bipolar system as the test pole and perform independent control on the test pole;

[0087] Independent control of the test pole in the bipolar system means performing separate control and adjustment on the test pole so that the test pole is not affected by other factors (such as the overall state of the system). This control method has the characteristics of strong pertinence, simple operation, and high flexibility.

[0088] Those skilled in the art should know how to perform independent control of the test pole in the bipolar system. Those skilled in the art can perform independent control of the test pole according to the actual situation.

[0089] The application of independent control in the bipolar system not only improves the flexibility and reliability of the system but also enables more precise control under different working conditions to meet specific requirements and goals.

[0090] Connect the no-load voltage boosting test device to the CLCC converter and its control system.

[0091] The no-load voltage boosting test device and the preset protection device are electrically connected to the CLCC converter and its control system. The connection may include signal lines, power lines, etc., and the connection is used to transmit monitoring data, control instructions, etc. Through the connection, the no-load voltage boosting test device and the preset protection device can realize the functions of voltage application and monitoring of the converter.

[0092] Put the preset protection device into operation. In the preferred embodiment of the present invention, the preset protection device includes an overcurrent protection device, an overvoltage protection device, a differential protection device, and a ground protection device.

[0093] Then start the no-load voltage boosting test device and load the output DC voltage to the corresponding test pole of the CLCC converter during the test;

[0094] Those skilled in the art should know that in the no-load voltage application test, the preset protection device plays a protective role for the CLCC converter and its control system, ensuring the safe operation of the CLCC converter and its control system during the no-load voltage application test. The preset protection device will monitor the operating state and voltage parameters of the converter. When abnormal conditions are detected, measures such as cutting off the power supply or issuing an alarm will be taken immediately to prevent equipment damage or accidents.

[0095] Those skilled in the art should know that the no-load voltage application test operation includes an uncontrolled charging stage, a controllable charging stage, a DC voltage boosting stage, and a steady state stage, etc. During these stages, the no-load voltage application test device will send corresponding control commands to the converter to adjust its output voltage.

[0096] In the controllable charging stage of the present invention, the thyristor trigger angles of the CLCC converter are adjusted according to the set first trigger angle command value, so as to adjust the conduction moments of the thyristors, and further adjust the DC voltage to ensure a smooth voltage rising process without abnormal fluctuations. In a preferred embodiment of the present invention, the first trigger angle command value is set based on the initial trigger angle test value, the rated DC voltage of the test pole, etc.

[0097] The first trigger angle command value is set according to the following formula:

[0098] ;

[0099] where k represents the kth sampling point, that is, the kth first trigger angle command value calculation point; is the trigger angle command value at the kth sampling point; is the initial trigger angle test value; is the DC voltage change correlation coefficient. Preferably, the sampling interval is set to 1 second; the sampling interval is the calculation interval.

[0100] The DC voltage change correlation coefficient is shown in the following formula:

[0101] ;

[0102] where is the voltage adjustment coefficient, is the rated DC voltage of the test pole.

[0103] The voltage adjustment coefficient is shown in the following formula:

[0104] ;

[0105] where is the trigger angle command value at the kth sampling point, is the trigger angle measurement value at the kth sampling point.

[0106] When the first test mode startup condition is met, the converter valve enters the first mode of the CLCC converter and keeps the firing angle and the firing angle command value unchanged within the set first time period by using a suspended reference value through pole control;

[0107] The first test mode startup condition is as follows:

[0108] ;

[0109] Wherein, is the firing angle command value at the k-th sampling point, is the test mode startup coefficient, is the measured firing angle value at the k-th sampling point.

[0110] The first mode of the CLCC converter is the CLCC mode. After the converter valve enters the CLCC mode, an no-load voltage application test is performed on the IGBT.

[0111] Preferably, after keeping the firing angle command value unchanged within the set first time period, the firing angle can be continuously adjusted to change the DC voltage value of the test pole at a set change rate. When the second test mode startup condition is met, the converter valve enters the second mode of the CLCC converter and keeps the firing angle command value unchanged within the set second time period, then enters the DC voltage boost stage, and finally enters the steady state stage, thus completing the no-load voltage application test. The set change rate is 1 kV / s.

[0112] The second test mode startup condition is as described by the following formula:

[0113] ;

[0114] Wherein, is the DC voltage at the k-th sampling point, is the test mode startup coefficient, is the rated DC voltage of the test pole.

[0115] The second mode of the CLCC converter is the LCC mode. After the converter valve enters the LCC mode, an no-load voltage application test is performed on the thyristor.

[0116] Preferably, after keeping the firing angle command value unchanged within the set first time period, it can also enter the DC voltage boost stage, automatically raise the DC voltage to the rated voltage, change the DC voltage value of the test pole at a set change rate. When the second test mode startup condition is met, the converter valve enters the second mode of the CLCC converter, and then enters the steady state stage, thus completing the no-load voltage application test;

[0117] After the test is completed, the output voltage of the no-load voltage application test device is reduced at a set rate until the voltage drops to zero, and the test pole is automatically blocked. The set rate is 1 kV / s.

[0118] Check whether there are any abnormal phenomena, such as overheating, damage, etc., in the IGBT module, thyristor module and other test equipment. If there are any abnormalities, they should be dealt with in a timely manner.

[0119] This application also discloses an open-circuit voltage application test system for a CLCC converter based on an open-circuit voltage application test method, including a test pole control module, a test start module, a first trigger angle adjustment module, a second trigger angle adjustment module and a test termination module:

[0120] The test pole control module selects the positive / negative pole as the test pole in the bipolar system and independently controls the test pole;

[0121] The test start module puts the preset protection device into operation, then starts the open-circuit voltage application test device, and loads the output DC voltage to the corresponding test pole of the CLCC converter;

[0122] The first trigger angle adjustment module adjusts the trigger angles of the thyristors of the CLCC converter according to the set first trigger angle command value, thereby adjusting the DC voltage. When the first test mode start condition is met, the converter valve enters the first mode of the CLCC converter and keeps the trigger angle command value unchanged within the set first time period;

[0123] The second trigger angle adjustment module, after the first trigger angle adjustment module finishes running, continues to adjust the trigger angle to make the DC voltage value of the test pole change at the set change rate. When the second test mode start condition is met, the converter valve enters the second mode of the CLCC converter and keeps the trigger angle command value unchanged within the set second time period, thereby completing the open-circuit voltage application test;

[0124] The test termination module, after the test is over, reduces the output voltage of the open-circuit voltage application test device at the set rate until the voltage drops to zero, and automatically locks the test pole.

[0125] This disclosure may be a system, a method, and / or a computer program product. The computer program product may include a computer-readable storage medium having thereon computer-readable program instructions for causing a processor to implement various aspects of this disclosure.

[0126] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. A computer-readable storage medium can be, for example—but not limited to—an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), a memory stick, a floppy disk, a mechanically encoded device, such as a punched card or raised structures in grooves having instructions stored thereon, and any suitable combination of the foregoing. The computer-readable storage medium as used herein is not construed as an instantaneous signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagated through a waveguide or other transmission medium (e.g., an optical pulse through an optical fiber cable), or an electrical signal transmitted through a wire.

[0127] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to respective computing / processing devices, or can be downloaded to an external computer or an external storage device through a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include a copper transmission cable, an optical fiber transmission, a wireless transmission, a router, a firewall, a switch, a gateway computer, and / or an edge server. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in each computing / processing device.

[0128] Computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state-setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages such as C++, and conventional procedural programming languages such as the "C" language or similar programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet service provider). In some embodiments, by using the state information of the computer-readable program instructions to customize an electronic circuit, such as a programmable logic circuit, a field-programmable gate array (FPGA), or a programmable logic array (PLA), the electronic circuit can execute the computer-readable program instructions to implement various aspects of the present disclosure.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent substitutions, and any modification or equivalent substitution that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A no-load pressure test method for a CLCC converter, characterized in that: include: In the bipolar system, the positive or negative electrode is selected as the test electrode, and the test electrode is independently controlled; Put the preset protection device into operation, then start the no-load pressure test device and load the output DC voltage to the corresponding test pole of the CLCC converter; The trigger angle of each thyristor of the CLCC converter is adjusted according to the set first trigger angle command value, thereby adjusting the DC voltage. When the first test mode start condition is met, the converter valve enters the first mode of the CLCC converter and keeps the trigger angle command value unchanged within the set first time period; After keeping the trigger angle command value unchanged within the set first period, continue to adjust the trigger angle so that the DC voltage value of the test pole changes according to the set change rate. When the start condition of the second test mode is met, the converter valve enters the second mode of the CLCC converter and keeps the trigger angle command value unchanged within the set second period, thereby completing the no-load pressurization test; After the test is completed, the output voltage of the no-load pressure test device is reduced at a set rate until the voltage drops to zero, and the test pole is automatically locked.

2. The no-load pressurization test method according to claim 1, characterized in that: The preset protection devices include an overcurrent protection device, an overvoltage protection device, a differential protection device and a grounding protection device.

3. The no-load pressurization test method according to claim 1, characterized in that: The first trigger angle command value is set according to the following formula: ； Where, k represents the kth sampling point; is the trigger angle command value at the kth sampling point; is the initial test value of the trigger angle; is the correlation coefficient of DC voltage change; the initial test value of the trigger angle is 150°~170°.

4. The no-load pressurization test method according to claim 3, characterized in that: The DC voltage change correlation coefficient is shown in the following formula: ； in, is the voltage regulation factor, is the rated DC voltage of the test pole.

5. The no-load pressurization test method according to claim 4, characterized in that: The voltage adjustment factor is shown below: ； in, is the trigger angle command value at the kth sampling point, is the trigger angle measurement value at the kth sampling point.

6. The no-load pressurization test method according to claim 1, characterized in that: The first test mode start condition is: ； in, is the trigger angle command value at the kth sampling point, is the test mode start coefficient, is the trigger angle measurement value at the kth sampling point.

7. The no-load pressurization test method according to claim 1, characterized in that: The first mode of the CLCC converter is the CLCC mode. After the converter valve enters the CLCC mode, a no-load pressure test is performed on the IGBT.

8. The no-load pressurization test method according to claim 6, characterized in that: The start condition of the second test mode is as follows: ； ； in, is the DC voltage at the kth sampling point, is the test mode start coefficient, is the rated DC voltage of the test pole.

9. The no-load pressurization test method according to claim 1, characterized in that: The second mode of the CLCC converter is the LCC mode. After the converter valve enters the LCC mode, a no-load pressure test is performed on the thyristor.

10. A no-load pressure test system for a CLCC converter using the no-load pressure test method according to any one of claims 1 to 9, characterized in that: It includes a test pole control module, a test start module, a first trigger angle adjustment module, a second trigger angle adjustment module and a test termination module: The test pole control module selects the positive pole / negative pole as the test pole in the bipolar system and independently controls the test pole; The test start module puts the preset protection device into operation, then starts the no-load pressure test device to load the output DC voltage to the test pole corresponding to the CLCC converter; The first trigger angle adjustment module adjusts the trigger angle of each thyristor of the CLCC converter according to the set first trigger angle command value, thereby adjusting the DC voltage. When the first test mode start condition is met, the converter valve enters the first mode of the CLCC converter and keeps the trigger angle command value unchanged within the set first time period; The second trigger angle adjustment module, after the operation of the first trigger angle adjustment module is completed, continues to adjust the trigger angle so that the DC voltage value of the test pole changes according to the set change rate. When the start condition of the second test mode is met, the converter valve enters the second mode of the CLCC converter and keeps the trigger angle command value unchanged within the set second time period, thereby completing the no-load pressurization test; The test termination module reduces the output voltage of the no-load pressurization test device at a set rate after the test is completed until the voltage drops to zero, and automatically locks the test pole.

Images