Method for verifying one-time wiring correctness of full-bridge and half-bridge sub-module mixed converter valve

Abstract

The invention discloses a full-bridge and half-bridge sub-module mixed converter valve primary wiring correctness verification method, which comprises the following steps that: when the direct current side of a converter valve is short-circuited, each bridge arm reserves one full-bridge sub-module and one half-bridge sub-module, and other sub-modules are short-circuited; a direct-current power supply with one phase being positive and the other phase being negative is connected into the two phases, full-bridge sub-module capacitors of an upper bridge arm of one phase and a lower bridge arm of the other phase are charged, half-bridge sub-module capacitors are bypassed, at the moment, the voltage of the full-bridge sub-modules is half of the direct-current voltage of the direct-current power supply, and the voltage of the half-bridge sub-modules is 0; capacitors of the full-bridge and half-bridge sub-modules of the lower bridge arm of one phase and the upper bridge arm of the other phase are charged, and the voltage of the full-bridge and half-bridge sub-modules is 1 / 4 of the direct-current voltage of the direct-current power supply, so that the wiring of the converter valve is judged to be correct according to the characteristics. The debugging progress of the flexible direct current power transmission project is prevented from being influenced by wiring errors of the converter valve, and the project is put into operation on schedule.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flexible direct current transmission, in particular to a full-bridge and half-bridge sub-module hybrid converter valve primary connection correctness verification method. BACKGROUND

[0002] The full-bridge (FBSM) and half-bridge (HBSM) sub-module hybrid converter valve exhibits significant comprehensive benefits in the field of flexible direct current transmission by combining the technical advantages of both. The full-bridge sub-module has negative level output capability and can autonomously clear direct current side short circuit faults, greatly improving system reliability; while the half-bridge sub-module has simple structure, low cost and small loss. The hybrid scheme, by reasonably configuring the proportion of both, maintains strong fault ride-through capability while reducing the overall cost and operating loss of the converter valve. At present, this technology is mainly applied to scenarios with high requirements for safety and economy, such as offshore wind power transmission (which requires high reliability to deal with cable faults) and asynchronous grid interconnection (which requires consideration of fault isolation and operating efficiency).

[0003] Through the analysis of the construction and debugging experience of flexible direct current projects, it is found that there are cases where the flexible direct current project is affected by the debugging progress due to the connection error of the converter valve. In order to ensure that the connection error can be found and rectified before the system debugging, it is necessary to carry out research on the correctness verification method of the primary connection of the converter valve.

[0004] The traditional DC converter valve primary connection correctness verification scheme is shown in FIG. 1, in which one piece of thyristor level is randomly taken in each single valve of the converter valve, the other thyristor levels are short-circuited by a temporary short-circuit line, and a 12-pulse rectifier connection mode is temporarily connected. The positive and negative voltages on the direct current side are led out, and according to the calculation, the corresponding direct current load resistor is connected on the direct current side. The specific verification method is as follows: Figure 1 (1) Disconnect the low-voltage side connection of the booster transformer, check whether the phase sequence and phase angle requirements of the test power source and the ignition voltage signal of the control and protection device are consistent.

[0005] (2) After checking and confirming that the synchronization signal is normal, disconnect the test power source, adjust the booster transformer to zero, and connect the low-voltage side connection of the booster transformer.

[0006] (3) Adjust the voltage regulator, power on the converter transformer, unlock the converter valve, adjust the trigger angle, record the valve side voltage and waveform at each angle, and analyze whether the control connection of the synchronization loop and the trigger control loop is perfect.

[0007] Due to the great difference in converter valve topology and control method between traditional DC and flexible DC, the existing traditional DC converter valve primary connection correctness verification method cannot be referenced by flexible DC transmission projects. SUMMARY

[0008] ​To solve the technical problems existing in the prior art, the application provides a flexible direct current full-bridge and half-bridge sub-module hybrid converter valve primary wiring correctness verification method, which avoids affecting the debugging progress of the flexible direct current transmission project due to the converter valve wiring error and provides a reference for the debugging of the subsequent flexible direct current project.

[0009] To this end, the application adopts the following technical scheme: a full-bridge and half-bridge sub-module hybrid converter valve primary wiring correctness verification method, and the content is as follows: When the converter valve direct current side is short-circuited, one full-bridge sub-module and one half-bridge sub-module are reserved in each bridge arm, and the remaining sub-modules are short-circuited; one direct current power supply with one phase being positive and the other phase being negative is connected in two phases, the full-bridge sub-module capacitors of the upper bridge arm of one phase and the lower bridge arm of the other phase are charged, and the half-bridge sub-module capacitors are bypassed, at this time, the full-bridge sub-module voltage is half of the direct current voltage of the direct current power supply, and the half-bridge sub-module voltage is 0; the full-bridge and half-bridge sub-module capacitors of the lower bridge arm of one phase and the upper bridge arm of the other phase are charged, at this time, the full-bridge and half-bridge sub-module voltage is 1 / 4 of the direct current voltage of the direct current power supply, and the full-bridge and half-bridge sub-module voltage is 1 / 4 of the direct current voltage of the direct current power supply, and the full-bridge and half-bridge sub-module voltage is 1 / 4 of the direct current voltage of the direct current power supply.

[0010] Further, when the converter valve direct current side is disconnected, one full-bridge sub-module and one half-bridge sub-module are reserved in each bridge arm, and the remaining sub-modules are short-circuited; one direct current power supply with one phase being positive and the other phase being negative is connected in two phases, the full-bridge and half-bridge sub-modules of the lower bridge arm of one phase and the upper bridge arm of the other phase are charged through anti-parallel diodes, and the full-bridge sub-module capacitors of the upper bridge arm of one phase and the lower bridge arm of the other phase are charged, and the half-bridge sub-module capacitors are bypassed; when the full-bridge sub-module capacitors of the upper and lower bridge arms of one phase and the upper and lower bridge arms of the other phase have voltage, only the half-bridge sub-modules of the lower bridge arm of one phase and the upper bridge arm of the other phase have voltage, and the half-bridge sub-modules of the upper bridge arm of one phase and the lower bridge arm of the other phase have no voltage, the full-bridge and half-bridge sub-module voltage is 1 / 4 of the direct current voltage of the direct current power supply, and the full-bridge and half-bridge sub-module voltage is 1 / 4 of the direct current voltage of the direct current power supply.

[0011] Further, the two phases are AB phase, BC phase or AC phase.

[0012] Further, before the primary wiring correctness verification of the converter valve, it is necessary to confirm that the system to be verified meets the following conditions: 1) The connection between the corresponding phase and neutral line of the grid side of the converter transformer has been completed; 2) The test of the converter transformer has been completed, and the test result is qualified; 3) The installation and debugging of the converter valve wiring and the protection control system are completed; 4) The single valve inspection test is completed by the converter valve equipment manufacturer, and the test program and the temporary setting of the protection outlet are completed by the control and protection equipment manufacturer; 5) The switches and knife switches related to the main circuit of the converter valve have the operation conditions; 6) The related sub-modules of the converter valve have been reliably bypassed. 7) The converter valve is isolated from the AC system and the DC system.

[0013] The present application has the following beneficial effects: the present application judges the correctness of the primary connection of the converter valve according to the different voltages of the full-bridge and half-bridge sub-modules when the DC side is short-circuited and when the DC side is disconnected, avoids the influence of the incorrect connection of the converter valve on the debugging progress of the flexible DC power transmission project, and ensures that the project is put into operation on schedule. The primary connection verification method of the converter valve of the flexible DC power transmission project provided by the present application is simple and easy to implement, and provides a reference for the debugging of subsequent flexible DC power transmission projects. BRIEF DESCRIPTION OF DRAWINGS

[0014] To more clearly illustrate the technical solutions in the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0015] Figure 1 It is a traditional DC converter valve primary connection correctness verification scheme diagram; Figure 2 It is a wiring diagram of the full-bridge and half-bridge sub-module hybrid converter valve primary connection correctness verification method of the present application when the DC side is short-circuited. Figure 3 It is a wiring diagram of the full-bridge and half-bridge sub-module hybrid converter valve primary connection correctness verification method of the present application when the DC side is disconnected. DETAILED DESCRIPTION

[0016] The technical solutions of the present application will be described below in conjunction with the drawings. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort also belong to the protection scope of the present application.

[0017] The present embodiment provides a full-bridge and half-bridge sub-module hybrid converter valve primary connection correctness verification method.

[0018] Before the primary connection correctness verification of the converter valve, it is necessary to confirm that the system to be verified satisfies the following conditions: 1) The connection between the corresponding phase and neutral line of the grid side of the converter transformer has been completed; 2) The test of the converter transformer has been completed, and the test result is qualified; 3) The installation and debugging of the converter valve connection and the protection control system are completed; 4) The single valve inspection test is completed by the converter valve equipment manufacturer, and the test program and the temporary setting of the protection outlet are completed by the control and protection equipment manufacturer; 5) The switches and breakers related to the main circuit of the converter valve have the operating conditions; 6) The sub-modules related to the converter valve have been reliably bypassed; 7) The converter valve is isolated from the AC system and the DC system.

[0019] The above primary wiring correctness verification method includes a primary wiring correctness verification method for a full-bridge and half-bridge sub-module mixed converter valve for flexible DC when the DC side is short-circuited and a primary wiring correctness verification method for a full-bridge and half-bridge sub-module mixed converter valve for flexible DC when the DC side is disconnected.

[0020] The primary wiring correctness verification method for the full-bridge and half-bridge sub-module mixed converter valve for flexible DC when the DC side is short-circuited, as shown in Figure 2 , has the following content: One full-bridge module and one half-bridge module are reserved in each bridge arm, and the remaining modules are short-circuited. The verification method for the wiring correctness of the upper and lower bridge arms corresponding to the AB phase is introduced by taking the AB phase as an example.

[0021] When the AB phase is connected to a DC power supply with a positive A phase and a negative B phase, the charging current direction is as shown in Figure 2 , the full-bridge sub-module capacitors of the A phase upper bridge arm and the B phase lower bridge arm are charged, and the half-bridge sub-module capacitors are bypassed. At this time, the full-bridge sub-module voltage is half of the DC voltage Udc of the DC power supply, and the half-bridge sub-module voltage is 0. The full-bridge and half-bridge sub-module capacitors of the A phase lower bridge arm and the B phase upper bridge arm are charged. At this time, the full-bridge and half-bridge sub-module voltage is 1 / 4 of the DC voltage Udc, and the correctness of the primary wiring of the converter valve is judged by this feature.

[0022] The verification methods for the B and C phases and the A and C phases are similar and are not described in detail.

[0023] The primary wiring correctness verification method for the full-bridge and half-bridge sub-module mixed converter valve for flexible DC when the DC side is disconnected, as shown in Figure 3 , has the following content: One full-bridge module and one half-bridge module are reserved in each bridge arm, and the remaining modules are short-circuited. The verification method for the wiring correctness of the upper and lower bridge arms corresponding to the AB phase is introduced by taking the AB phase as an example.

[0024] When the AB phase is connected to a DC power supply with a positive A phase and a negative B phase, the charging current direction is as shown in Figure 3As shown, the full-bridge sub-modules and the half-bridge sub-modules of the lower bridge arm of phase A and the upper bridge arm of phase B are charged through the anti-parallel diodes, the full-bridge sub-module capacitors of the upper bridge arm of phase A and the lower bridge arm of phase B are charged, and the half-bridge sub-module capacitors are bypassed. Therefore, when the full-bridge sub-module capacitors of the upper and lower bridge arms of phase A and the upper and lower bridge arms of phase B all have voltage, only the half-bridge sub-modules of the lower bridge arm of phase A and the upper bridge arm of phase B have voltage, and the half-bridge sub-modules of the upper bridge arm of phase A and the lower bridge arm of phase B have no voltage, the characteristics are judged to determine that the primary wiring of the converter valve is correct.

[0025] The checking methods of phase B and phase C and phase A and phase C are similar, and are not described in detail.

[0026] The above description of the embodiments is for the purpose of facilitating the understanding and application of the present application by those skilled in the art. Those skilled in the art can easily make various modifications to the above embodiments, and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the above embodiments, and the improvements and modifications made to the present application by those skilled in the art according to the disclosure of the present application should be within the scope of protection of the present application.

Claims

1. A method for verifying the primary wiring correctness of a full-bridge and half-bridge sub-module hybrid converter valve, characterized in that, when the DC side of the converter valve is short-circuited, each bridge arm retains one full-bridge sub-module and one half-bridge sub-module, and the remaining sub-modules are short-circuited; a DC power supply with one phase positive and the other phase negative is connected in two phases, the full-bridge sub-module capacitors of the upper bridge arm of one phase and the lower bridge arm of the other phase are charged, and the half-bridge sub-module capacitors are bypassed; at this time, the full-bridge sub-module voltage is half of the DC voltage of the DC power supply, and the half-bridge sub-module voltage is 0; the full-bridge and half-bridge sub-module capacitors of the lower bridge arm of one phase and the upper bridge arm of the other phase are all charged; at this time, the full-bridge and half-bridge sub-module voltage is 1 / 4 of the DC voltage of the DC power supply, and the wiring correctness of the converter valve is determined by this feature.

2. The method for verifying the primary wiring correctness of a full-bridge and half-bridge sub-module hybrid converter valve according to claim 1, characterized in that, when the DC side of the converter valve is disconnected, each bridge arm retains one full-bridge sub-module and one half-bridge sub-module, and the remaining sub-modules are short-circuited; a DC power supply with one phase positive and the other phase negative is connected in two phases, the full-bridge and half-bridge sub-modules of the lower bridge arm of one phase and the upper bridge arm of the other phase are all charged through anti-parallel diodes, and the full-bridge sub-module capacitors of the upper bridge arm of one phase and the lower bridge arm of the other phase are charged, and the half-bridge sub-module capacitors are bypassed; when the full-bridge sub-module capacitors of the upper and lower bridge arms of one phase and the upper and lower bridge arms of the other phase all have voltage, only the half-bridge sub-modules of the lower bridge arm of one phase and the upper bridge arm of the other phase have voltage, and the half-bridge sub-modules of the upper bridge arm of one phase and the lower bridge arm of the other phase have no voltage, the wiring correctness of the converter valve is determined by this feature.

3. The primary connection correctness verification method of a full-bridge and half-bridge sub-module hybrid converter valve according to claim 1 or 2, characterized in that, The two phases are AB phase, BC phase or AC phase.

4. The primary connection correctness verification method of a full-bridge and half-bridge sub-module hybrid conversion valve according to claim 1 or 2, characterized in that, Before verifying the primary wiring correctness of the converter valve, it is necessary to confirm that the system to be verified meets the following conditions: 1) The connection between the corresponding phase and neutral line of the grid side of the converter transformer has been completed; 2) The converter transformer test has been completed, and the test results are qualified; 3) The converter valve wiring and protection control system installation and commissioning are completed; 4) The single valve inspection test is completed by the converter valve equipment manufacturer, and the test program and protection outlet are temporarily set by the control and protection equipment manufacturer; 5) The switches and disconnectors related to the main circuit of the converter valve have the operating conditions; 6) The related sub-modules of the converter valve have been reliably bypassed; 7) The converter valve is isolated from the AC system and the DC system.

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