A method and apparatus for wiring verification

Abstract

This application discloses a wiring verification method and apparatus, belonging to the field of power electronics technology. The wiring verification method includes: charging a submodule of a converter valve; verifying the wiring phase sequence of the first voltage measuring point and the converter transformer based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point, and the current phase sequence of the second current measuring point; performing open-loop control on the converter valve after unlocking it; comparing the actual voltage of the first voltage measuring point with the control system reference wave to verify the phase sequence of the converter valve and the wiring method of the converter transformer, and obtaining the wiring verification result. The wiring verification method of this application only utilizes the first AC switch, first voltage measuring point, first current measuring point, and second current measuring point inherent in the flexible DC system itself, solving the problem that the phase sequence and wiring method of the converter valve cannot be verified due to the removal of the valve-side switch and valve-side voltage measuring point, thus improving the verification and adaptation capability of the flexible DC system.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a wiring verification method and device. Background Technology

[0002] With the rapid development and widespread application of new energy power generation technologies, the proportion of new energy power generation in power systems is gradually increasing. Flexible DC transmission technology based on modular multilevel converters (MMC) has advantages such as independent control of active and reactive power and the ability to supply power to passive systems, making it a key technology for solving the problem of large-scale grid connection and transmission of new energy.

[0003] With the promotion of flexible DC transmission system applications, flexible DC projects are gradually eliminating valve-side switches and valve-side voltage measurement points, leaving only grid-side switches and grid-side voltage measurement points. This makes it impossible to implement methods such as the converter valve phase sequence verification method based on the tripped valve-side switch, which uses full-process phase-locked and open-loop unlocked control of the grid voltage to output the valve-side voltage, and the converter transformer connection method verification method that compares the grid-side voltage with the valve-side voltage during charging. Summary of the Invention

[0004] A wiring verification method and apparatus are provided to solve the problem that the phase sequence and wiring method of the converter valve cannot be verified due to the removal of the valve-side switch and valve-side voltage measurement point.

[0005] In a first aspect, embodiments of this application provide a wiring verification method applied to a flexible DC transmission system. The flexible DC transmission system includes a converter transformer and a converter valve. The converter transformer is connected to an AC power source via a first AC switch. A first voltage measuring point and a first current measuring point are provided between the first AC switch and the converter transformer. A second current measuring point is provided between the converter transformer and the converter valve. The wiring verification method includes:

[0006] Close the first AC switch to charge the submodule of the converter valve; Based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point, and the current phase sequence of the second current measuring point, the wiring phase sequence of the first voltage measuring point and the wiring phase sequence of the converter transformer are verified and corrected. Once charging is complete, disconnect the first AC switch and unlock the commutation valve; The converter valve operates for a first duration using open-loop control with a fixed voltage amplitude and frequency; wherein, the open-loop control is based on a control system reference wave to control the converter valve. By comparing the actual voltage at the first voltage measurement point with the reference wave of the control system, the phase sequence of the converter valve and the wiring method of the converter transformer are verified to obtain the wiring verification result.

[0007] In one embodiment of this application, charging the submodule of the converter valve includes: Under the condition of pressure testing, all the sub-modules of the converter valve are charged; wherein, the pressure testing is performed by applying the voltage of the AC power supply. In the case of low-voltage pressurization verification, a portion of the sub-modules of the converter valve are selected for charging, while the remaining unselected sub-modules are bypassed; wherein, the low-voltage pressurization verification is performed by applying voltage from an external low-voltage power supply.

[0008] In one embodiment of this application, the step of verifying the wiring phase sequence of the first voltage measuring point based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point, and the current phase sequence of the second current measuring point includes: If the voltage phase sequence at the first voltage measuring point is correct, then the wiring phase sequence at the first voltage measuring point is correct. If the voltage phase sequence of the first voltage measuring point is incorrect, but the current phase sequence of the first current measuring point is correct, check and correct the wiring phase sequence of the first voltage measuring point. If the voltage phase sequence at the first voltage measuring point is incorrect, or the current phase sequence at the first current measuring point is incorrect, check the power supply wiring; if the power supply wiring is correct, determine that the wiring phase sequence at the first voltage measuring point is incorrect and correct it.

[0009] In one embodiment of this application, verifying the wiring phase sequence of the converter transformer based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point, and the current phase sequence of the second current measuring point includes: If the current phase sequence at the second current measuring point is correct, then the wiring phase sequence of the converter transformer is confirmed to be correct. If the current phase sequence at the second current measuring point is incorrect, check and correct the wiring phase sequence of the converter transformer.

[0010] In one embodiment of this application, disconnecting the first AC switch and unlocking the converter valve upon completion of charging includes: After disconnecting the first AC switch, the converter valve is unlocked after a first delay time.

[0011] In one embodiment of this application, the operation of the converter valve for a first duration using open-loop control with a fixed voltage amplitude and frequency includes: The instantaneous value of the DC voltage or the peak value of the valve side line voltage at the moment the converter valve is unlocked is used as the DC bias of the bridge arm. The open-loop voltage d-axis reference value is set to a fixed amplitude, and the voltage q-axis reference value is set to 0 voltage; the control system reference wave is generated by performing dq transformation on a phase signal, and the bridge arm AC reference wave is obtained after being transformed by the converter transformer; The open-loop control bridge arm reference wave is obtained based on the bridge arm DC bias and the bridge arm AC reference wave.

[0012] In one embodiment of this application, the method for obtaining the phase signal includes: The phase signal is generated using a fixed frequency; or; Before disconnecting the first AC switch, the phase-locked loop is controlled to synchronize the power supply voltage phase; after disconnecting the first AC switch, the phase-locked loop is switched to a fixed frequency, and the phase is accumulated on the synchronized power supply voltage phase to obtain the phase signal.

[0013] In one embodiment of this application, the fixed frequency is: Preset fundamental frequency; or; Before disconnecting the first AC switch, the phase-locked loop tracks and obtains the instantaneous frequency or average frequency.

[0014] In one embodiment of this application, comparing the actual voltage at the first voltage measuring point with the reference wave of the control system to verify the phase sequence of the converter valve and the wiring method of the converter transformer includes: Based on the correct phase sequence of the first voltage measuring point and the correct phase sequence of the converter transformer, and assuming the correct actual voltage phase sequence of the first voltage measuring point, the phase sequence of the converter valve is determined to be correct. If the phase sequence of the converter valve is correct, compare the actual voltage at the first voltage measurement point with the phase of the reference wave of the control system. If they are consistent, the wiring method of the converter transformer is determined to be correct. If they are inconsistent, the wiring method of the converter transformer is determined to be incorrect, and the wiring error is assessed based on the phase difference.

[0015] Secondly, embodiments of this application also provide a wiring verification device for verifying the wiring of a flexible DC transmission system. The flexible DC transmission system includes a converter transformer and a converter valve. The converter transformer is connected to an AC power source via a first AC switch. A first voltage measuring point and a first current measuring point are provided between the first AC switch and the converter transformer. A second current measuring point is provided between the converter transformer and the converter valve. The wiring verification device includes: A charging module is used to close the first AC switch to charge the submodule of the converter valve; The first verification module is used to verify and correct the wiring phase sequence of the first voltage measuring point and the wiring phase sequence of the converter transformer based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point and the current phase sequence of the second current measuring point. The unlocking module is used to disconnect the first AC switch and unlock the converter valve when charging is complete. An open-loop control module is used to operate the converter valve for a first duration using open-loop control with a fixed voltage amplitude and frequency; wherein, the open-loop control is based on a preset control system reference wave to control the converter valve; The second verification module is used to compare the actual voltage at the first voltage measurement point with the reference wave of the control system, verify the phase sequence of the converter valve, and verify the wiring method of the converter transformer to obtain the wiring verification result.

[0016] The beneficial effects of this application are as follows: The wiring verification method of this application only utilizes the first AC switch, first voltage measuring point, first current measuring point, and second current measuring point inherent in the flexible DC system itself. It does not rely on the eliminated valve-side switch and valve-side voltage measuring point, nor does it require the addition of additional verification measuring points to the system. Based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point, and the current phase sequence of the second current measuring point, the wiring phase sequence of the first voltage measuring point and the wiring phase sequence of the converter transformer are verified and corrected. Combined with open-loop control, the phase sequence of the converter valve and the wiring method of the converter transformer can be verified. This solves the problem that the phase sequence and wiring method of the converter valve cannot be verified due to the elimination of the valve-side switch and valve-side voltage measuring point, and improves the verification and adaptation capability of the flexible DC system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a diagram of the flexible DC transmission system architecture provided in the embodiments of this application; Figure 2 This is a schematic diagram of the wiring verification method steps provided in the embodiments of this application; Figure 3 This is a schematic diagram of a submodule bypass provided in an embodiment of this application; Figure 4 This is an open-loop control block diagram provided in an embodiment of this application; Figure 5This is a schematic diagram of phase generation based on a fixed frequency provided in an embodiment of this application; Figure 6 This is a schematic diagram of phase generation based on a trip switch provided in an embodiment of this application; Figure 7 The phase generation waveform diagram based on the trip switch provided in the embodiments of this application; Figure 8 This is an architectural diagram of the wiring verification device provided in the embodiments of this application.

[0019] Explanation of reference numerals in the attached figures: 11. AC power supply; 12. First AC switch; 13. First voltage measuring point; 14. First current measuring point; 15. Converter transformer; 16. Second current measuring point; 17. Converter valve; 171. Submodule; 172. Shorting wire; 18. First node; 19. Bridge arm voltage calculation unit; 21. Charging module; 22. First verification module; 23. Unlocking module; 24. Open-loop control module; 25. Second verification module. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] Embodiments of this application provide a wiring verification method applied to flexible DC transmission systems, such as... Figure 1As shown, the flexible DC transmission system includes a converter transformer 15 and a converter valve 17. The converter transformer 15 is connected to the AC power supply 11 via a first AC switch 12. A first voltage measuring point 13 and a first current measuring point 14 are provided between the first AC switch 12 and the converter transformer 15. A second current measuring point 16 is provided between the converter transformer 15 and the converter valve 17. Figure 2 As shown, the wiring verification method includes: Step S1: Close the first AC switch 12 to charge the submodule 171 of the converter valve 17; Step S2: Based on the voltage phase sequence of the first voltage measuring point 13, the current phase sequence of the first current measuring point 14, and the current phase sequence of the second current measuring point 16, verify and correct the wiring phase sequence of the first voltage measuring point 13 and the wiring phase sequence of the converter transformer 15. Step S3: When charging is complete, disconnect the first AC switch 12 and unlock the converter valve 17. Step S4: Open-loop control with fixed voltage amplitude and frequency is used to make the converter valve 17 run for a first duration; wherein, the open-loop control is to control the converter valve 17 based on the control system reference wave; Step S5: Compare the actual voltage at the first voltage measurement point 13 with the reference wave of the control system, verify the phase sequence of the converter valve 17, and verify the wiring method of the converter transformer 15 to obtain the wiring verification result.

[0023] In some embodiments, step S1, charging the submodule 171 of the converter valve 17 includes a pressure test scenario and a low-pressure test scenario.

[0024] When the phase sequence verification is carried out using the original pressure plus pressure method, the sub-module 171 that performs charging is all sub-modules 171 of each bridge arm; like Figure 3 As shown, when the phase sequence is checked using the low-voltage pressurization method, the submodule 171 that performs the charging is the submodule 171 that selects the incoming low-voltage pressurization test for each bridge arm, and the submodule 171 that does not select the incoming low-voltage pressurization test is shorted by the jumper wire 172.

[0025] For the first AC switch 12 and the first voltage measuring point 13, when the phase sequence verification is carried out by the original voltage plus voltage method, that is, when the phase sequence verification of the entire valve group is carried out by the AC power supply 11 of the flexible DC transmission system, the first AC switch 12 is the AC incoming switch of the converter valve 17 of the flexible DC transmission system, and the first voltage measuring point 13 is the grid-side voltage measuring point of the original flexible DC transmission system. For the first AC switch 12 and the first voltage measuring point 13, when the phase sequence verification is performed using the low-voltage pressurization method, that is, when the newly added low-voltage power supply is used to pressurize part of the sub-module 171 of the converter valve 17 to carry out wiring verification, the newly added low-voltage power supply is connected to the first node 18. The first node 18 is located at the connection point between the original flexible DC transmission system AC incoming switch and grid-side voltage measuring point and the flexible DC transmission system. When the newly added low-voltage power supply is connected, the connection between the original flexible DC transmission system AC incoming switch and grid-side voltage measuring point and the flexible DC transmission system is disconnected.

[0026] In some embodiments, the first current measuring point 14 and the second current measuring point 16 are the original grid-side current measuring point and valve-side current measuring point of the flexible DC transmission system. In step S2, the wiring phase sequence of the first voltage measuring point 13 is verified based on the voltage phase sequence of the first voltage measuring point 13, the current phase sequence of the first current measuring point 14, and the current phase sequence of the second current measuring point 16, including: Determine whether the voltage phase sequence of the first voltage measuring point 13 is correct. If the voltage phase sequence of the first voltage measuring point 13 is correct, then the wiring phase sequence of the first voltage measuring point 13 is correct.

[0027] If the voltage phase sequence at the first voltage measuring point 13 is incorrect, but the current phase sequence at the first current measuring point 14 is correct, check and correct the wiring phase sequence at the first voltage measuring point 13.

[0028] If the voltage phase sequence at the first voltage measuring point 13 is incorrect, and the current phase sequence at the first current measuring point 14 is incorrect, check the power supply wiring; if the power supply wiring is correct, determine that the wiring phase sequence at the first voltage measuring point 13 is incorrect and correct it.

[0029] The method for determining whether the voltage phase sequence of the first voltage measuring point 13 is correct is as follows: if the voltage phase sequence of the first voltage measuring point 13 is a three-phase sequence of A, B, C with a phase difference of 120°, then the voltage phase sequence of the first voltage measuring point 13 is considered correct, and thus the wiring phase sequence of the first voltage measuring point 13 is determined to be correct.

[0030] If the voltage phase sequence of the three phases ABC at the first voltage measuring point 13 is not 120° different from each other in the order of A, B, C, the following method can be used to determine whether the wiring method of the first voltage measuring point 13 is incorrect.

[0031] Method 1: After eliminating the possibility of wiring errors in AC power supply 11 by tracing the wires, it can be concluded that the wiring of the first voltage measuring point 13 is incorrect, and the wiring of the first voltage measuring point 13 should be checked and corrected.

[0032] Method 2: Use the current phase sequence at the first current measuring point 14 as an auxiliary criterion: If the phase sequence of the first current measuring point 14 is correct, since the possibility of both the power supply wiring and the wiring of the first current measuring point 14 being incorrect in phase sequence is relatively small, it can be temporarily assumed that the power supply wiring is correct and the wiring of the first voltage measuring point 13 is incorrect, and the wiring of the first voltage measuring point 13 should be checked first. After confirming that the wiring of the first voltage measuring point 13 is incorrect by means of tracing the wires, the wiring of the first voltage measuring point 13 should be corrected; if the wiring of the first voltage measuring point 13 is correct, it is assumed that both the power supply wiring and the wiring of the first current measuring point 14 are incorrect in phase sequence, and the investigation and correction should be carried out.

[0033] If the phase sequence of the first current measuring point 14 is also incorrect, since the possibility of the first voltage measuring point 13 and the first current measuring point 14 having the same incorrect phase sequence is relatively small, it can be temporarily assumed that the power supply wiring is incorrect, and the power supply wiring method should be checked first. After confirming the power supply wiring error by tracing the wires, the power supply wiring should be corrected; if the power supply wiring method is correct, it is assumed that the first voltage measuring point 13 and the first current measuring point 14 have the same incorrect phase sequence, and the investigation and correction should be carried out.

[0034] In some embodiments, step S2 involves verifying the connection phase sequence of the converter transformer 15 based on the voltage phase sequence of the first voltage measuring point 13, the current phase sequence of the first current measuring point 14, and the current phase sequence of the second current measuring point 16, including: If the phase sequence of the current at the second current measuring point 16 is correct, then the phase sequence of the converter transformer 15 is considered to be correct. If the current phase sequence at the second current measuring point 16 is incorrect, the wiring configuration of the converter transformer 15 should be checked first. After confirming the wiring error of the converter transformer 15 by means of tracing the wires, the wiring of the converter transformer 15 should be corrected. If the wiring configuration of the converter transformer 15 is correct, then the phase sequence of the wiring at the second current measuring point 16 is considered to be incorrect, and the process of checking and correcting it should be carried out.

[0035] In some embodiments, step S3, upon completion of charging, involves disconnecting the first AC switch 12 and unlocking the converter valve 17, including: After disconnecting the first AC switch 12, the converter valve 17 is unlocked after a first delay time.

[0036] After submodule 171 completes charging, this application issues a command to disconnect the first AC switch 12 and unlocks the converter valve 17 after a first delay. The first delay can be on the order of seconds, based on the principle that the first AC switch 12 is completely disconnected and the voltage drop of submodule 171 is small. Here, "small voltage drop of submodule 171" means that the voltage of submodule 171 after the drop is greater than the energy extraction voltage.

[0037] It should be noted that in other embodiments of this application, determining whether the phase sequence of the first voltage measuring point 13 is correct can also be performed after charging is completed in step S3 and before the trip switch.

[0038] This application keeps the first AC switch 12 closed only during the charging phase. The first AC switch 12 is disconnected before the converter valve 17 is unlocked, so that the flexible DC transmission system is disconnected from the power source. The entire process of the subsequent open-loop operation of the converter valve 17 is not electrically connected to the power grid, thus avoiding the grid impact problem caused by wiring errors and ensuring the safety of the power grid and the flexible DC transmission system.

[0039] In some embodiments, such as Figure 4 As shown, step S4 employs open-loop control with a fixed voltage amplitude and frequency to operate the converter valve 17 for a first duration, including: The instantaneous value of the DC voltage or the peak value of the valve side line voltage at the moment of unlocking the converter valve 17 is used as the DC bias Uref_PZ of the bridge arm. Based on the upper and lower bridge arm topology of the converter valve 17, the DC bias Uref_PZ of the bridge arm needs to be evenly distributed to the upper and lower bridge arms to obtain the DC component Uref_dc.

[0040] The open-loop voltage d-axis reference value Uref_d is set to a fixed amplitude, and the voltage q-axis reference value is set to 0 voltage. After performing dq transformation on a phase signal θ, the control system reference wave Uref_adc is generated. After being transformed by converter transformer 15, the bridge arm AC reference wave ujo_ref is obtained.

[0041] Bridge arm voltage calculation unit 19 obtains the open-loop control bridge arm reference wave based on the bridge arm DC bias and the bridge arm AC reference wave ujo_ref. The calculation formula is as follows:

[0042] Where upj represents the upper bridge arm reference wave and unj represents the lower bridge arm reference wave.

[0043] In some embodiments, such as Figure 5 As shown, the method for obtaining the phase signal θ is as follows: the phase-locked loop uses a fixed frequency f0 to generate the phase throughout the experiment, and the AC voltage measured after unlocking is independent of the grid voltage phase; the phase signal θ is obtained by angular frequency and integral calculations from the fixed frequency f0.

[0044] In some embodiments, such as Figure 6 As shown, the method for obtaining the phase signal θ is as follows: before disconnecting the first AC switch 12, the phase-locked loop is controlled to synchronize the power supply voltage phase; after disconnecting the first AC switch 12, the phase-locked loop is switched to a fixed frequency f0, and the phase is accumulated on the synchronized power supply voltage phase to obtain the phase signal.

[0045] The phase-locked loop (PLL) of this application is a switchable-mode PLL with two operating states. When the first AC switch 12 is closed for charging, the PLL synchronizes the power supply voltage phase. Taking the power supply voltage signal Us to be tracked as an example, the power supply voltage signal Us is transformed from a three-phase coordinate system (a, b, c) to a two-phase coordinate system (α, β). The positive-sequence fundamental component Usαβ+ is extracted from the transformed target signal Usαβ, and then a dq transformation is performed on the positive-sequence fundamental component Usαβ+. If the phase output of the PLL is synchronized with the phase of the power supply voltage signal, then the q-axis component Usq in the dq coordinate system should be equal to 0. The q-axis component Usq can represent the phase error. This application uses proportional-integral control on the q-axis component Usq to track the power supply voltage phase.

[0046] like Figure 6 As shown, after the AC switch trips, the phase-locked loop switches to a fixed frequency f0, as follows: Figure 7 As shown, taking the three-phase voltage as the power supply voltage signal to be tracked as an example, although the frequency waveform of the grid voltage of phase A is interrupted, the phase waveform of the phase-locked loop will not be interrupted. Starting from the phase value at the moment of the trip switch, the phase-locked loop continues to accumulate phase on the basis of the original synchronous power supply phase, so as to achieve the effect that the phase of the flexible DC AC voltage measured after the trip switch is unlocked is basically consistent with the phase of the grid voltage.

[0047] In some embodiments, the fixed frequency f0 is a preset fundamental frequency, such as 50Hz.

[0048] In some embodiments, the fixed frequency f0 is the frequency obtained by the phase-locked loop control before the trip switch. This frequency can be the instantaneous value f at the moment of trip switch, or it can be the average value over a period of time before the trip switch.

[0049] In some embodiments, step S5 involves comparing the actual voltage at the first voltage measurement point 13 with the control system reference wave to verify the phase sequence of the converter valve 17 and the wiring configuration of the converter transformer 15, including: Based on the correct phase sequence of the first voltage measuring point 13 and the correct phase sequence of the converter transformer 15, and assuming the correct actual voltage phase sequence of the first voltage measuring point 13, the phase sequence of the converter valve 17 is determined to be correct. If the phase sequence of the converter valve 17 is correct, compare the actual voltage of the first voltage measuring point 13 with the phase of the control system reference wave. If they are consistent, the wiring method of the converter transformer 15 is correct. If they are inconsistent, the wiring method of the converter transformer 15 is incorrect, and the wiring error is assessed based on the phase difference.

[0050] This application determines whether the phase sequence of the converter valve 17 is correct by comparing the reference wave of the control system with the actual value of the first voltage measuring point 13, and further clarifies whether the wiring method of the converter transformer 15 is correct.

[0051] Since the correctness of the power supply wiring, the phase sequence of the converter transformer 15, and the phase sequence of the first voltage measuring point 13 has been ensured in step S2, if the phase sequence of the voltage measurement value of the first voltage measuring point 13 is correct at this time, then the phase sequence of the converter valve 17 can be considered correct.

[0052] In some embodiments, the connection method of the converter transformer 15 in this application refers to the yd11 connection method in which the low-voltage side winding of the converter transformer adopts a star connection, the low-voltage side winding adopts a delta connection, and the low-voltage side line voltage leads the high-voltage side by 30°.

[0053] In some embodiments, the connection method of the converter transformer 15 in this application refers to the connection method in which the high-voltage side winding of the converter transformer adopts a star connection, the low-voltage side winding adopts a star connection, and the phase difference between the high-voltage and low-voltage side line voltages is 0°.

[0054] If the phase sequence of the converter valve 17 is correct, and the voltage measurement value of the first voltage measuring point 13 is in phase with the reference wave of the control system, then the wiring method of the converter transformer 15 is considered correct; if the voltage measurement value of the first voltage measuring point 13 is not in phase with the reference wave of the control system, then the wiring method of the converter transformer 15 is considered incorrect, and the wiring error is assessed based on the phase difference.

[0055] After the converter valve 17 of this application is unlocked, it adopts open-loop control with fixed voltage amplitude and frequency. The wiring verification is achieved by comparing the reference wave of the control system with the actual voltage of the first voltage measurement point 13, avoiding parameter coupling interference caused by closed-loop control. The verification result is accurate, and the implementation of open-loop control is simple and easy to execute.

[0056] Embodiments of this application also provide a wiring verification device for verifying the wiring of a flexible DC transmission system. The flexible DC transmission system includes a converter transformer 15 and a converter valve 17. The converter transformer 15 is connected to an AC power supply 11 via a first AC switch 12. A first voltage measuring point 13 and a first current measuring point 14 are provided between the first AC switch 12 and the converter transformer 15. A second current measuring point 16 is provided between the converter transformer 15 and the converter valve 17. Figure 8 As shown, the wiring verification device includes: The charging module 21 is used to close the first AC switch 12 to charge the submodule 171 of the commutation valve 17. The first verification module 22 is used to verify and correct the wiring phase sequence of the first voltage measuring point 13 and the wiring phase sequence of the converter transformer 15 based on the voltage phase sequence of the first voltage measuring point 13, the current phase sequence of the first current measuring point 14, and the current phase sequence of the second current measuring point 16. The unlocking module 23 is used to disconnect the first AC switch 12 and unlock the converter valve 17 when charging is complete. The open-loop control module 24 is used to operate the converter valve 17 for a first duration using open-loop control with a fixed voltage amplitude and frequency; wherein, the open-loop control is to control the converter valve 17 based on a preset control system reference wave. The second verification module 25 is used to compare the actual voltage of the first voltage measuring point 13 with the reference wave of the control system, verify the phase sequence of the converter valve 17, and verify the wiring method of the converter transformer 15 to obtain the wiring verification result.

[0057] The wiring verification method and apparatus provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A wiring verification method, characterized in that, This method is applied to flexible DC transmission systems, which include converter transformers and converter valves. The converter transformer is connected to an AC power source via a first AC switch. A first voltage measuring point and a first current measuring point are provided between the first AC switch and the converter transformer. A second current measuring point is provided between the converter transformer and the converter valve. The wiring verification method includes: Close the first AC switch to charge the submodule of the converter valve; Based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point, and the current phase sequence of the second current measuring point, the wiring phase sequence of the first voltage measuring point and the wiring phase sequence of the converter transformer are verified and corrected. Once charging is complete, disconnect the first AC switch and unlock the commutation valve; The converter valve operates for a first duration using open-loop control with a fixed voltage amplitude and frequency; wherein, the open-loop control is based on a control system reference wave to control the converter valve. By comparing the actual voltage at the first voltage measurement point with the reference wave of the control system, the phase sequence of the converter valve and the wiring method of the converter transformer are verified to obtain the wiring verification result.

2. The wiring verification method according to claim 1, characterized in that, The charging of the submodule of the converter valve includes: Under the condition of pressure testing, all the sub-modules of the converter valve are charged; wherein, the pressure testing is performed by applying the voltage of the AC power supply. In the case of low-voltage pressurization verification, a portion of the sub-modules of the converter valve are selected for charging, while the remaining unselected sub-modules are bypassed; wherein, the low-voltage pressurization verification is performed by applying voltage from an external low-voltage power supply.

3. The wiring verification method according to claim 1, characterized in that, The step of verifying the wiring phase sequence of the first voltage measuring point based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point, and the current phase sequence of the second current measuring point includes: If the voltage phase sequence at the first voltage measuring point is correct, then the wiring phase sequence at the first voltage measuring point is correct. If the voltage phase sequence of the first voltage measuring point is incorrect, but the current phase sequence of the first current measuring point is correct, check and correct the wiring phase sequence of the first voltage measuring point. If the voltage phase sequence at the first voltage measuring point is incorrect, or the current phase sequence at the first current measuring point is incorrect, check the power supply wiring; if the power supply wiring is correct, determine that the wiring phase sequence at the first voltage measuring point is incorrect and correct it.

4. The wiring verification method according to claim 1, characterized in that, The step of verifying the wiring phase sequence of the converter transformer based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point, and the current phase sequence of the second current measuring point includes: If the current phase sequence at the second current measuring point is correct, then the wiring phase sequence of the converter transformer is confirmed to be correct. If the current phase sequence at the second current measuring point is incorrect, check and correct the wiring phase sequence of the converter transformer.

5. The wiring verification method according to claim 1, characterized in that, Upon completion of charging, disconnecting the first AC switch and unlocking the converter valve includes: After disconnecting the first AC switch, the converter valve is unlocked after a first delay time.

6. The wiring verification method according to claim 1, characterized in that, The method of using open-loop control with fixed voltage amplitude and frequency to operate the converter valve for a first duration includes: The instantaneous value of the DC voltage or the peak value of the valve side line voltage at the moment the converter valve is unlocked is used as the DC bias of the bridge arm. The open-loop voltage d-axis reference value is set to a fixed amplitude, and the voltage q-axis reference value is set to 0 voltage; the control system reference wave is generated by performing dq transformation on a phase signal, and the bridge arm AC reference wave is obtained after being transformed by the converter transformer; The open-loop control bridge arm reference wave is obtained based on the bridge arm DC bias and the bridge arm AC reference wave.

7. The wiring verification method according to claim 6, characterized in that, The method for obtaining the phase signal includes: The phase signal is generated using a fixed frequency; or; Before disconnecting the first AC switch, the phase-locked loop is controlled to synchronize the power supply voltage phase; after disconnecting the first AC switch, the phase-locked loop is switched to a fixed frequency, and the phase is accumulated on the synchronized power supply voltage phase to obtain the phase signal.

8. The wiring verification method according to claim 7, characterized in that, The fixed frequency is: Preset fundamental frequency; or; Before disconnecting the first AC switch, the phase-locked loop tracks and obtains the instantaneous frequency or average frequency.

9. The wiring verification method according to claim 7, characterized in that, The actual voltage at the first voltage measurement point is compared with the reference wave of the control system to verify the phase sequence of the converter valve and the wiring method of the converter transformer, including: Based on the correct phase sequence of the first voltage measuring point and the correct phase sequence of the converter transformer, and assuming the correct actual voltage phase sequence of the first voltage measuring point, the phase sequence of the converter valve is determined to be correct. If the phase sequence of the converter valve is correct, compare the actual voltage at the first voltage measurement point with the phase of the reference wave of the control system. If they are consistent, the wiring method of the converter transformer is determined to be correct. If they are inconsistent, the wiring method of the converter transformer is determined to be incorrect, and the wiring error is assessed based on the phase difference.

10. A wiring verification device, characterized in that, The wiring verification device is used to verify the wiring of a flexible DC transmission system. The flexible DC transmission system includes a converter transformer and a converter valve. The converter transformer is connected to an AC power source via a first AC switch. A first voltage measuring point and a first current measuring point are provided between the first AC switch and the converter transformer. A second current measuring point is provided between the converter transformer and the converter valve. The wiring verification device includes: A charging module is used to close the first AC switch to charge the submodule of the converter valve; The first verification module is used to verify and correct the wiring phase sequence of the first voltage measuring point and the wiring phase sequence of the converter transformer based on the voltage phase sequence of the first voltage measuring point, the current phase sequence of the first current measuring point and the current phase sequence of the second current measuring point. The unlocking module is used to disconnect the first AC switch and unlock the converter valve when charging is complete. An open-loop control module is used to operate the converter valve for a first duration using open-loop control with a fixed voltage amplitude and frequency; wherein, the open-loop control is based on a preset control system reference wave to control the converter valve; The second verification module is used to compare the actual voltage at the first voltage measurement point with the reference wave of the control system, verify the phase sequence of the converter valve, and verify the wiring method of the converter transformer to obtain the wiring verification result.

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