A method and system for fault-tolerant operation of a large-capacity sea wind converter multi-tube

Abstract

The application discloses a large-capacity sea wind converter multi-tube fault tolerance operation method and system, relates to the wind power generation technical field, and is applied to a sea wind power converter system connected in parallel with multiple same-structure converters. The operation method comprises the following steps: locating a fault switch tube, defining a half-bridge arm with the fault switch tube and a half-bridge arm without the fault switch tube as a fault half-bridge arm and a healthy half-bridge arm, and closing a drive signal of the fault half-bridge arm; judging whether the sea wind power converter system is a fault tolerance operation scene according to the position relationship between the fault half-bridge arm and the healthy half-bridge arm; if the sea wind power converter system is the fault tolerance operation scene, a split-inductor composite clamping bridge arm structure is adopted to reconstruct a fault phase, and the conversion function of the fault phase is recovered. According to the application, the 'cutting off half bridge arm' strategy is adopted for the multi-tube fault type with the fault tolerance operation condition, the split-inductor composite clamping bridge arm is constructed by using the remaining healthy half-bridge arm, the function recovery of the fault phase is realized, and the robustness of the system in the multi-fault scene is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and in particular to a method and system for fault-tolerant operation of a large-capacity offshore wind converter with multiple tubes. Background Technology

[0002] Offshore wind power systems are characterized by high power output, complex environments, and difficult maintenance. As the core power conversion device, the converter's reliability directly impacts the stable operation of the power generation system. In actual operation, power switching transistors are prone to open-circuit faults due to electrical and thermal stresses. Currently, offshore wind power converters often employ a parallel structure of multiple converter units to improve output power and fault tolerance. Existing fault-tolerance strategies are mostly designed for single-transistor faults. For multi-transistor fault scenarios, the entire bridge arm or converter unit is often disconnected, leading to a significant drop in output power or even system shutdown, resulting in severe power generation losses. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a fault-tolerant operation method and system for a large-capacity offshore wind converter with multiple switching transistors, which can avoid disconnecting the entire bridge arm or converter unit when multiple switching transistors fail, thereby improving the system's fault tolerance and operational reliability.

[0004] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0005] In a first aspect, the present invention provides a fault-tolerant operation method for a large-capacity offshore wind converter with multiple converters of the same structure connected in parallel. The operation method includes:

[0006] Locate the faulty switch transistor, define the half-bridge arm with and without the faulty switch transistor as the faulty half-bridge arm and the healthy half-bridge arm, and shut down the drive signal of the faulty half-bridge arm.

[0007] Based on the positional relationship between the faulty half-bridge arm and the healthy half-bridge arm, determine whether the offshore wind power converter system is in a fault-tolerant operation scenario;

[0008] In fault-tolerant operating scenarios, a split inductor-type composite clamping bridge arm structure is used to reconstruct the faulty phase and restore its converter function.

[0009] Optionally, determining whether the offshore wind power converter system is in a fault-tolerant operating scenario includes:

[0010] If all faulty half-bridge arms corresponding to all faulty switch tubes have healthy half-bridge arms at the same position, then the offshore wind power converter system is a fault-tolerant operating scenario.

[0011] Optionally, if the number of fault switch transistors is 1, then there is only one faulty half-bridge arm, which has a healthy half-bridge arm in the same position, which is a fault-tolerant operation scenario.

[0012] Optionally, if the number of fault switch transistors is 2, the two fault switch transistors belong to the same bridge arm and same position half bridge arm, the same bridge arm and different position half bridge arm, the same phase and different bridge arm and same position half bridge arm, the same phase and different bridge arm and different position half bridge arm, different phase and same bridge arm and same position half bridge arm, different phase and different bridge arm and different position half bridge arm, different phase and different bridge arm and same position half bridge arm, or different phase and different bridge arm and different position half bridge arm.

[0013] If the number of parallel converters with the same structure in the offshore wind power converter system is 2, and they belong to the following categories: same-arm half-arm in the same position, same-arm half-arm in different position, same-phase half-arm half-arm in different position, different-arm half-arm in the same position, different-arm half-arm in different position, different-phase half-arm half-arm in different position, different-arm half-arm in the same position, or different-phase half-arm half-arm in different position, it is a fault-tolerant operation scenario; if they belong to the same-phase half-arm half-arm in the same position, it is a non-fault-tolerant operation scenario.

[0014] Optionally, if it belongs to a half-bridge arm with different positions in the same phase, the fault phase is reconstructed using a split inductor-type composite clamping bridge arm structure, which includes: retaining the healthy half-bridge arm in the two bridge arms corresponding to the fault switch tubes, and reconstructing the fault phase.

[0015] Optionally, if the operation is not fault-tolerant, the offshore wind power converter system shall be shut down for maintenance.

[0016] Secondly, this invention provides a high-capacity offshore wind converter multi-tube fault-tolerant operation system, applicable to an offshore wind power converter system in which multiple converters of the same structure are connected in parallel. The operation system includes:

[0017] The fault isolation module is configured to locate the faulty switch transistor, define the half-bridge arm with and without the faulty switch transistor as the faulty half-bridge arm and the healthy half-bridge arm, and shut down the drive signal of the faulty half-bridge arm.

[0018] The scenario judgment module is configured to determine whether the offshore wind power converter system is in a fault-tolerant operation scenario based on the positional relationship between the faulty half-bridge arm and the healthy half-bridge arm.

[0019] The fault-tolerant operation module is configured to reconstruct the faulty phase and restore its converter function by using a split inductor-type composite clamping bridge arm structure if the operation scenario is fault-tolerant.

[0020] Thirdly, the present invention provides an electronic device, including a processor and a storage medium;

[0021] The storage medium is used to store instructions;

[0022] The processor is configured to operate according to the instructions to perform the steps according to the method described above.

[0023] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0024] Fifthly, the present invention provides a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of the above-described method.

[0025] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0026] This invention provides a method and system for multi-tube fault-tolerant operation of a large-capacity offshore wind converter. It employs a multi-tube fault-tolerant operation strategy, utilizing a "half-bridge arm removal" fault-tolerant approach to achieve continuous system operation under multi-tube faults, expanding the fault-tolerant fault scenarios. By reconstructing the faulty phase using a split inductor structure, the system can still maintain half of its rated power output after a fault, reducing power loss. It is suitable for applications with high reliability requirements, such as offshore wind power, improving the overall availability of the system. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the multi-tube fault-tolerant operation method for a large-capacity offshore wind converter provided in an embodiment of the present invention.

[0028] Figure 2 This is a topology diagram of an offshore wind power converter system based on an A-NPC converter provided in an embodiment of the present invention;

[0029] Figure 3 This is a topology diagram of an offshore wind power converter system based on dual A-NPC converters provided in an embodiment of the present invention;

[0030] Figure 4 This is a diagram of the single-tube fault-tolerant operation structure provided in an embodiment of the present invention;

[0031] Figure 5 This is a fault-tolerant operation structure diagram provided by an embodiment of the present invention, showing that dual-tube failures occur at the same position on the same bridge arm.

[0032] Figure 6 This is a fault-tolerant operation structure diagram of a dual-tube fault occurring at different positions in the same bridge arm, as provided in an embodiment of the present invention.

[0033] Figure 7 This is a fault-tolerant operation structure diagram of a dual-tube fault occurring at the same position in different bridge arms of the same phase, provided by an embodiment of the present invention;

[0034] Figure 8This is a structural diagram of the entire bridge arm operation mode where the faulty switch tube is located when a dual-tube fault occurs in different positions of different bridge arms in the same phase, provided by an embodiment of the present invention.

[0035] Figure 9 This is a structural diagram of the operating mode of the half-arm where the faulty switch tube is located when a dual-tube fault occurs in different positions of different bridge arms in the same phase, as proposed in this invention.

[0036] Figure 10 This is an equivalent circuit diagram of the converter system after disconnecting the half of the bridge arm where the faulty switch transistor is located when a dual-transistor fault occurs in different positions of different bridge arms in the same phase, provided by an embodiment of the present invention.

[0037] Figure 11 This is a fault-tolerant operation structure diagram of a dual-tube fault occurring at the same position in different bridge arms, provided by an embodiment of the present invention;

[0038] Figure 12 This is a fault-tolerant operation structure diagram of a dual-tube fault occurring in different positions of the same bridge arm, as provided in an embodiment of the present invention;

[0039] Figure 13 This is a fault-tolerant operation structure diagram of a dual-tube fault occurring at the same position in different phases and different bridge arms, provided by an embodiment of the present invention;

[0040] Figure 14 This is a fault-tolerant operating structure diagram of a dual-tube fault occurring in a different phase, different bridge arm, and different position, provided in an embodiment of the present invention.

[0041] Figure 15 This is a diagram of a fault-tolerant operating structure where three tube failures occur in the same bridge arm, as provided in an embodiment of the present invention.

[0042] Figure 16 This is a diagram of a fault-tolerant operating structure for a three-tube failure occurring in a different phase and different bridge arm, provided in an embodiment of the present invention.

[0043] Figure 17 This is a diagram of a fault-tolerant operation structure for three-tube failures occurring in different bridge arms, provided in an embodiment of the present invention.

[0044] Figure 18 This is a diagram of a fault-tolerant operation structure for four-tube failures occurring in different phases and different bridge arms, provided in an embodiment of the present invention.

[0045] Figure 19 This is a diagram of a fault-tolerant operation structure for four tubes failing in different bridge arms, provided in an embodiment of the present invention.

[0046] Figure 20 This is a diagram of the five-pipe fault-tolerant operation structure provided in an embodiment of the present invention;

[0047] Figure 21 This is a diagram of the six-tube fault-tolerant operation structure provided in an embodiment of the present invention;

[0048] Figure 22 This invention provides a single-tube fault-tolerant operation: In phase a bridge arm aLeg1, the switching transistor S... a1 The waveforms of the grid-connected current and inductor current during fault-tolerant operation;

[0049] Figure 23 This invention provides a dual-transistor fault-tolerant operation: In phase a bridge arm aLeg1, the switching transistor S... a1 In phase b bridge arm bLeg2, the switching transistor S a10 Current waveform diagram during fault-tolerant operation;

[0050] Figure 24 This invention provides a dual-transistor fault-tolerant operation: In phase a bridge arm aLeg1, the switching transistor S... a1 In phase b bridge arm bLeg2, the switching transistor S a10 Current waveform diagram for reconstructing fault-tolerant operation during fault;

[0051] Figure 25 This invention provides a dual-transistor fault-tolerant operation: the switching transistor S in phase a arm aLeg1 and phase b arm bLeg1. a1 and S b1 Current waveform during fault-tolerant operation;

[0052] Figure 26 This invention provides a three-transistor fault-tolerant operation: In phase a bridge arm aLeg1, the switching transistor S... a1 In phase b bridge arm bLeg2, the switching transistor S b8 And the switching transistor S in phase c bridge arm cLeg1 c1 Current waveform diagram during fault-tolerant operation;

[0053] Figure 27 This invention provides a three-transistor fault-tolerant operation: the switching transistors S in bridge arms aLeg1, bLeg1, and cLeg1. a1 S b1 S c1 Current waveform diagram during fault-tolerant operation;

[0054] Figure 28 This invention provides a four-transistor fault-tolerant operation: the switching transistors S in bridge arms aLeg1, bLeg1, and cLeg1. a1 S b1 S c1 and the switching transistor S in phase a bridge arm aLeg2 a10 Waveforms of grid-connected current and inductor current during fault-tolerant operation;

[0055] Figure 29This invention provides a five-transistor fault-tolerant operation: the switching transistors S in bridge arms aLeg1, bLeg1, and cLeg1. a1 S b1 S c1 and the switching transistor S in aLeg2 and bLeg2 a10 S b10 Waveforms of grid-connected current and inductor current during fault-tolerant operation;

[0056] Figure 30 This invention provides a six-transistor fault-tolerant operation: the switching transistors S in bridge arms aLeg1, bLeg1, and cLeg1. a1 S b1 S c1 And the switching transistor S in aLeg2, bLeg2, and cLeg2 a10 S b10 S c10 Waveforms of grid current and inductor current during fault-tolerant operation. Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0058] Example 1

[0059] like Figure 1 As shown, this embodiment of the invention provides a fault-tolerant operation method for a large-capacity offshore wind converter with multiple converters of the same structure connected in parallel. The operation method includes:

[0060] Step S1: Locate the faulty switch transistor, define the half-bridge arm with and without the faulty switch transistor as the faulty half-bridge arm and the healthy half-bridge arm, and shut down the drive signal of the faulty half-bridge arm.

[0061] Step S2: Determine whether the offshore wind power converter system is in a fault-tolerant operation scenario based on the positional relationship between the faulty half-bridge arm and the healthy half-bridge arm; that is, if all faulty half-bridge arms corresponding to faulty switch tubes have healthy half-bridge arms in the same position, then the offshore wind power converter system is in a fault-tolerant operation scenario.

[0062] Step S3: If it is a fault-tolerant operation scenario, the faulty phase is reconstructed using a split inductor-type composite clamping bridge arm structure to restore its converter function; if it is a non-fault-tolerant operation scenario, the offshore wind power converter system is shut down for maintenance.

[0063] like Figure 2As shown, a topology diagram of an offshore wind power converter system based on A-NPC converters (#1, #2, ..., #N) is presented. The grid-side output of each converter is collected to an AC transformer, and after power conversion by the transformer, it is transmitted to the power grid. The circuit structure of each converter unit is the same.

[0064] like Figure 3 As shown, a topology diagram of an offshore wind power converter system based on dual A-NPC converters is presented. e a , e b and e c These represent three-phase power grids. The upper three-phase A-NPC converter is denoted as #1 converter, with each phase arm designated as Leg1. The lower three-phase A-NPC converter is denoted as #2 converter, with each phase arm designated as Leg2. Therefore, the arm corresponding to phase a in converter #1 can be called aLeg1, and the arm corresponding to phase a in converter #2 can be called aLeg2. The arms of the other two phases can be similarly represented. In phase a, aLeg1 is controlled by the switching transistor S. a1 -S a6 Composed of, aLeg2 consists of the switching transistor S a7 -S a12 The bridge arm output side is connected to a filter inductor. L a1 and L a2 Connected. C 1- C 4 represents the DC-side bus capacitor. C fa , C fb ,and C fc These are three-phase filter capacitors, and the configurations of the other two phases are the same as phase a.

[0065] exist Figure 3 In the offshore wind power converter system shown, during the positive half-cycle power transmission mode of the power grid, the switching transistor S... x1 and switching transistor S x2 Both are conducting, maintaining normal output. When the switching transistor S... x1 and S x2 When any switch in the circuit fails open, the bridge arm output pulse voltage wave is lost, making it difficult to maintain normal grid-connected operation. Therefore, for ease of explanation, switch S... x1 and switching transistor S x2 Similarly, as a half-bridge arm, the switching transistor S x3 and S x4 It can be used as a half-bridge arm, with the switching transistor S... x7 and Sx8 It can be used as a half-bridge arm, with the switching transistor S... x9 and S x10 It can be used as a half-bridge arm. When any switch in the half-bridge arm is open-circuited, it can be regarded as a fault in the half-bridge arm where that switch is located, requiring shutdown for maintenance or fault-tolerant operation.

[0066] For ease of explanation, the phase containing the faulty switch is called the faulty phase. Since each phase consists of two bridge arms connected in parallel, to distinguish them, the bridge arm containing the faulty switch is called the faulty bridge arm, and the remaining bridge arms are healthy bridge arms. The half-bridge arm containing the faulty switch is called the faulty half-bridge arm, and the rest are healthy half-bridge arms. In the faulty bridge arm, besides the faulty switch or the faulty half-bridge arm, the remaining components are healthy switches and healthy half-bridge arms, while in the healthy bridge arm, all components are healthy half-bridge arms. Furthermore, since the two parallel converter units use the same A-NPC circuit structure, the switches in the circuit can be in the same or different positions, such as switch S... x1 and switching transistor S x7 Located in the same position as the A-NPC circuit, while the switching transistor S... x1 and switching transistor S x8 Then it is in a different position. Similarly, half-bridge arms also have the distinction of being in the same position and being in different positions, such as when switched by transistor S. x1 S x2 The half-bridge arm is connected in series and consists of a switching transistor S x7 S x8 The half-bridge arms, connected in series, are in the same position, while the switching transistor S... x9 S x10 The half-bridge arms formed by the series connection are in opposite positions. Therefore, the fault-tolerant operation strategy for multi-transistors is specifically described as follows:

[0067] (1) If the number of fault switch tubes is 1, then there is only one faulty half-bridge arm, which has a healthy half-bridge arm at the same position, which is a fault-tolerant operation scenario.

[0068] like Figure 4 As shown, assume that the faulty switch is switch S of aLeg1. a1 At this time, the fault switch S a1 The redundant health switch is the switch S located in the same position. a7 When a single half-bridge arm fails in the converter, the system can still continue to operate by controlling the redundant healthy half-bridge arms, since there are always redundant healthy half-bridge arms. The fault-tolerant operating mode that can be adopted at this time is as follows: the drive of all switches in phase aLeg1 is shut down, the switches in aLeg2 are driven normally, and the operation mode of the switches in phases b and c remains unchanged. In this case, the output power of the converter system is limited to half of the rated power.

[0069] (2) If the number of fault switch tubes is 2, the two fault switch tubes belong to the same bridge arm and the same position half bridge arm, the same bridge arm and the opposite position half bridge arm, the same phase and the opposite bridge arm and the same position half bridge arm, the same phase and the opposite bridge arm and the opposite position half bridge arm, the opposite phase and the same bridge arm and the opposite position half bridge arm, the opposite phase and the opposite bridge arm and the opposite position half bridge arm, the opposite phase and the opposite bridge arm and the same position half bridge arm, or the opposite phase and the opposite bridge arm and the opposite position half bridge arm.

[0070] (2.1) As Figure 5 As shown, the two fault switch transistors belong to the same half-bridge arm and position. The fault switch transistors are switch transistors S and S, respectively. a1 and S a2 It can operate with fault tolerance. In fact, this scenario is similar to... Figure 4 The single-transistor failure scenario shown is equivalent because the switching transistor S... a1 and S a2 They are located in the same half-arm. During fault-tolerant operation, the drive of the switching transistor in aLeg1 is disabled, while the switching transistor in aLeg2 drives normally. Both phase B and phase C arms continue to drive normally. When a fault occurs in phase B or phase C, the operation is synchronized with the normal operation of the half-arm. Figure 5 Faults occurring in phase a are equivalent and can be operated in a fault-tolerant manner.

[0071] (2.2) As Figure 6 As shown, the two fault switch transistors belong to the same bridge arm but different positions half-bridge arm, and the fault switch transistors are S and S, respectively. a1 and S a3 It can operate with fault tolerance. It can be seen that at this time, all faulty switching transistors are located in aLeg1, and aLeg2 is a healthy bridge arm. During fault-tolerant operation, similar to the handling method described in (2.1) above, the drive of the switching transistors in aLeg1 is blocked, the switching transistors in aLeg2 drive normally, and the bridge arms of phases b and c continue to drive normally. When a fault occurs in phase b or phase c, it is similar to... Figure 6 Similar to the description in [the text], the converter can continue to operate at this time.

[0072] (2.3) such as Figure 7 As shown, the two fault switch transistors belong to the same phase, different bridge arms, and the same half-bridge arm. The fault switch transistors are S and S. a1 and S a7 The two faulty switches are located in the same position in both converter units, specifically on the outer side of the upper half of the A-NPC circuit. The faulty half-arm no longer has a redundant healthy half-arm, meaning the converter's a-phase no longer has a fully functional arm and cannot support normal output voltage. To prevent the fault from escalating, the converter needs to be shut down for maintenance. Figure 7 Similar to the description in the article, when a similar fault occurs in phase B or phase C, the converter cannot operate in a fault-tolerant manner.

[0073] (2.4) such as Figure 8 As shown, the two fault switch transistors belong to the same phase, different bridge arm, and different position half-bridge arm. The fault switch transistors are S and S, respectively. a1 and S a10 If the traditional fault-tolerant operation method is adopted, that is, the entire bridge arm containing the faulty switch is disconnected, then as follows: Figure 8 As shown in the figure, both bridge arms aLeg1 and aLeg2 are cut off, so there are no healthy bridge arms remaining in phase a, and the converter needs to be shut down.

[0074] This invention proposes a fault-tolerant operation mode for cutting off half of the bridge arm, as follows: Figure 9 As shown in the diagram, the half-bridge arm containing the faulty switch transistor is disconnected, leaving the healthy half-bridge arm among the remaining faulty bridge arms. Faulty switch transistor S a1 and S a10 The faulty half-bridge arm was disconnected, and bridge arms aLeg1 and aLeg2 remained connected by the healthy switch S. a3 S a4 and health switch S a7 S a8 The resulting healthy half-bridge arm. At this point, the equivalent circuit of the converter system is as follows: Figure 10 As shown, S ' xn ( x =b,c n =1,2,…,6), representing the equivalent switching transistors in phase b and phase c, respectively. From Figure 10 As can be seen from this, the equivalent circuit of phase a adopts a split inductor structure, which makes the inductance... L a2 and L a1 The converter system can still maintain operation even when the grid current flows through the grid during the positive and negative half-cycles respectively.

[0075] (2.5) such as Figure 11 As shown, the two fault switch transistors belong to the same half-bridge arm in different positions. The fault switch transistors are S1, S2, and S3, S4, S5, S6, S7, S8, S9, S10, S9, S11, S9, S12, S9, S13, S9, S14, S9, S15, S16, S17, S18, S19 ... a1 and S b1 The two faults occurred in opposite-phase arms, but both were located in the same position on the outer side of the upper arm. Figure 5 similar, Figure 11 In the middle, due to the faulty switch S a1 and S b1 The faulty half-bridge arm has a redundant healthy half-bridge arm, which is the healthy half-bridge arm in the same position in converter #2, allowing the converter to continue operating. The fault-tolerant operation method is similar when the fault occurs in the lower half-bridge arm or other phases.

[0076] (2.6) such as Figure 12As shown, the two fault switch transistors belong to different half-bridge arms with different positions and are S1, S2, and S3, S4, S5, S6, S7, S8, S9, S10, S9, S11, S9, S12, S9, S13, S9, S14, S9, S15, S9, S16, S17, S18, S19 ... a1 and S b3 The two faults occurred in opposite bridge arms, one in the upper half and the other in the lower half. Figure 11 Similar to that shown, due to the fault switch S a1 and S b3 The faulty half-bridge arm has a redundant healthy half-bridge arm, namely the switching transistor S. a7 and S b9 In the healthy half-bridge arm, the converter can operate with fault tolerance. Furthermore, the fault-tolerant operation mode is also consistent with... Figure 11 The method shown is similar. The drive of the switching transistors in aLeg1 and bLeg1 is shut down, while the switching transistors in aLeg2 and bLeg2 are driven normally. Both arms of phase c continue to be driven normally, and the converter continues to operate.

[0077] (2.7) For example Figure 13 As shown, the two fault switch transistors belong to the same half-bridge arm in different phases and different bridge arms. The fault switch transistors are S and S. a1 and S b7 However, they are all located outside the two converter units. (And) Figure 11 and Figure 12 Similar to that shown, due to the fault switch S a1 and S b7 The faulty half-bridge arm has a redundant healthy half-bridge arm, namely the switching transistor S. a7 and S b1 In the healthy half-arm of the converter, the converter can continue to operate. During fault-tolerant operation, the drive of the switching transistors in aLeg1 and bLeg2 is shut down, while the switching transistors in aLeg2 and bLeg1 drive normally. Both arms of phase c continue to drive normally, and the converter continues to operate.

[0078] (2.8) such as Figure 14 As shown, the two fault switch transistors belong to opposite phase, opposite bridge arm, and opposite position half-bridge arms. The fault switch transistors are S and S, respectively. a1 and S b9 The two faults occurred in opposite bridge arms and were on opposite sides. Figure 11 and Figure 12 Similar to that shown, due to the fault switch S a1 and S b9 The faulty half-bridge arm has a redundant healthy half-bridge arm, namely the switching transistor S. a7 and S b3In the healthy half-arm of the converter, the converter can continue to operate. During fault tolerance, the drive of the switching transistors in aLeg1 and bLeg2 is shut down, while the switching transistors in aLeg2 and bLeg1 drive normally. Both arms of phase c continue to drive normally, and the converter continues to operate.

[0079] from Figure 5 and Figure 6 It can be seen that the two fault-tolerant operating results when the dual-pipe failure occurs in the same bridge arm are equivalent. From Figure 7 As can be seen, when any two or more switching transistors fail in the same phase, different bridge arms, and the same half-bridge arm, the faulty half-bridge arm containing the faulty switching transistor has no redundant healthy half-bridge arms. The faulty phase cannot maintain normal output, and the converter cannot operate with fault tolerance. From... Figure 7 As can be seen, when any two or more switching transistor faults occur in the same phase but different bridge arm half-arms at different positions, the fault-tolerant operation mode of cutting off the entire bridge arm is difficult to achieve fault-tolerant operation for such faults. However, cutting off only half of the bridge arm can achieve fault-tolerant operation. Compared with the method of cutting off the entire bridge arm, the fault-tolerant operation mode proposed in this embodiment of the invention has more fault-tolerant operation scenarios, which can improve the reliability of converter operation and reduce power loss during faults.

[0080] according to Figures 11 to 14 , combined Figure 4 As can be seen from the fault-tolerant operation mode under single-transistor open circuit, a dual-transistor fault occurring in out-of-phase mode is equivalent to a combination of two single-transistor open circuit faults. Furthermore, the four fault-tolerant operation results are equivalent; subsequent fault-tolerant operation scenarios will only present a few independent fault-tolerant operation results.

[0081] (3) If the number of faulty switching transistors is 3, due to the large number of fault scenarios, it is difficult to list them all. Only three scenarios are given: the three faulty switching transistors are located in the same bridge arm, different phases and different bridge arms, and different phases and the same bridge arm, respectively.

[0082] (3.1) As Figure 15 As shown, a three-transistor fault occurs in the same bridge arm, and the faulty switching transistors are switching transistors S1, S2, and S3, S4, and S5, respectively. a1 S a2 and S a3 When aLeg1 is disconnected, only the healthy bridge arm aLeg2 is enabled, allowing the converter to continue operating. During fault-tolerant operation, the drive of the switching transistors in aLeg1 is shut down, while the switching transistors in aLeg2 drive normally. Both bridge arms of phases b and c continue to drive normally, allowing the converter to continue operating.

[0083] (3.2) As Figure 16 As shown, a three-transistor fault occurs in an out-of-phase bridge arm. The faulty switching transistors are switching transistors S1, S2, and S3, S4, S5, S6, S7, S8, S9 ... a1 Sb7 and S a10 Since there are no two or more switching transistor faults occurring in the same phase, different bridge arms, and the same location, a split inductor structure is used to reconstruct the faulty phase bridge arm. The converter is maintained by cutting off half of the bridge arm in a fault-tolerant manner.

[0084] (3.3) such as Figure 17 As shown, a three-transistor fault occurs in different bridge arms. The faulty switching transistors are switching transistors S1, S2, and S3, S4, S5, S6, S7, S8, S9 ... a1 S b1 and S c1 At this time, converter #1 is disabled, while converter #2 on the lower side remains enabled, transmitting all output power and maintaining the operation of the wind power converter. The operation is similar when a three-phase fault occurs in an out-of-phase, out-of-arm section of the three-phase power supply. Figure 17 The results shown are consistent, combined with Figure 4 The fault-tolerant operation mode when a single switch is open can be seen from the fault-tolerant operation mode when a three-phase out-of-phase bridge arm is fault-tolerant, which can be equivalent to a combination of the fault-tolerant operation modes of three single-phase faults.

[0085] (4) If the number of faulty switching transistors is 4, only two fault-tolerant operation scenarios are given: the four faulty switching transistors are located in different phases and different bridge arms and different bridge arms respectively.

[0086] (4.1) As Figure 18 As shown, a four-transistor fault occurred in an out-of-phase bridge arm. The faulty switching transistors are switching transistors S1, S2, and S3, S4, S5, S6, S7, S8, S9 ... a1 S a10 S b4 and S b7 By reconstructing the faulty phase bridge arm using a split inductor structure, the half of the bridge arm containing the faulty switch in phases a and b is cut off, while the switch in phase c continues to drive normally, thus achieving fault-tolerant operation.

[0087] (4.2) such as Figure 19 As shown, a four-transistor fault occurred in an out-of-phase bridge arm. The faulty switching transistors are switching transistors S1, S2, and S3, S4, S5, S6, S7, S8, S9 ... a1 S a3 S b4 and S c4 Fault-tolerant operation method and Figure 17 Similarly, this enables fault-tolerant operation of the converter system.

[0088] (5) If the number of faulty switching transistors is 5, since the failure of a single switching transistor is considered a failure of its corresponding half-arm, and each phase has a maximum of four switching transistors, when five switching transistors fail, the fault must occur in different phases. Here, we take a fault-tolerant operation scenario as an example, where the five faulty switching transistors are in different phases and different arms, such as... Figure 20 As shown, the fault-tolerant operation method and Figure 18Similarly, the faulty phase bridge arm of phase a is reconstructed using a split inductor structure, and phase cLeg1 of phase c is cut off, while only cLeg2 is enabled to maintain converter operation.

[0089] (6) If the number of faulty switching transistors is 6, only one fault-tolerant operation scenario for a six-transistor open-circuit fault is given, that is, the six faulty switching transistors are of different phases and different bridge arms. The other scenarios are equivalent, such as Figure 21 As shown above, fault-tolerant operation is only possible when any two or more faulty switching transistors are not in the same phase, different bridge arms, or the same position. Since there are many faulty switching transistors in a six-transistor open-circuit fault, there are relatively few fault-tolerant operation scenarios in this type of fault situation.

[0090] from Figures 18 to 21 It can be seen that when four or more switches fail, if any two or more faulty switches are not located in the same phase but different arms, two faults will inevitably occur in different arms of the same phase. In this case, if the fault-tolerant method of cutting off the entire arm is adopted, the faulty phase will be difficult to maintain operation. However, by reconstructing the faulty phase arm using a split inductor structure and cutting off half of the arm, a healthy half of the faulty arm remains, allowing the healthy switches to be used to achieve fault-tolerant operation of the converter under multiple switch faults. Furthermore, when the number of faulty switches is seven or more, at least two switches will inevitably be in the same position of the same phase arm, meaning there will inevitably be one faulty half-arm without redundant healthy half-arms. In this case, neither cutting off the entire arm nor cutting off half an arm can maintain converter operation; to prevent the fault from escalating, shutdown and maintenance are necessary.

[0091] like Figure 22 As shown, the switching transistor S in phase a bridge arm aLeg1 of the converter is... a1 The waveforms of the grid-connected current and inductor current during fault-tolerant operation. Switch S in phase a bridge arm aLeg1. a1 Fault, bridge arm aLeg1 is cut off, inductor L a1 The current is 0. During fault-tolerant operation, the grid current remains constant, and the inductance on the output side of phase a bridge arm aLeg2... L a2 The current is twice that before the fault and equal to the grid current, while the bridge arms of phases b and c remain normal, and the inductor currents of phases b and c remain unchanged. At this time, a fault-tolerant method of cutting off the entire aLeg1 bridge arm is used. It can be seen that the inductor... L a2 The current is equal to the grid current.

[0092] like Figure 23 As shown, the switching transistor S in phase a bridge arm aLeg1 of the converter is... a1 In phase b bridge arm bLeg2, the switching transistor Sa10 Current waveform diagram during fault-tolerant operation. At this time, the converter remains operational, phase a arm aLeg1 and phase b arm bLeg2 are disconnected, and the inductor... L a1 and L b2 The current is 0, and the inductance is... L a2 and L b1 The current is equal to the grid current. There is no fault in phase c. The inductance of phase c is... L c2 The current is equal to half of the current flowing into the grid at this time.

[0093] When a dual-transistor fault occurs in the same phase, the switching transistor S in bridge arm aLeg1 a1 and the switching transistor S in aLeg2 a10 Fault-tolerant operation waveform as follows Figure 24 As shown, two switches in phase a fail, but the two failures are not in the same position on the two bridge arms. Using the fault-tolerant operation mode of cutting off half a bridge arm proposed in this embodiment, the remaining healthy switches in the complementary positions of phase a form a complete bridge arm. At this time, the lower half of bridge arm aLeg1 and the upper half of bridge arm aLeg2 are the remaining healthy half of the bridge arm. After fault-tolerant operation, the lower half of bridge arm aLeg1 operates in the negative half-cycle of the power grid, and the inductor... L a1 The current is in the negative half-wave, and the upper half-arm of aLeg2 operates in the positive half-cycle of the power grid. The inductor... L a2 The current is a positive half-wave. Phase a can still achieve the complete converter function, and there are no faults in phases b and c. The inductor current remains unchanged, and the converter continues to operate. If the entire bridge arm is cut off, phase a cannot work normally and needs to be shut down. This invention proposes a fault-tolerant operation mode with half a bridge arm cut off, which adds a scenario where fault-tolerant operation is possible under a dual-tube fault. Figure 25 For the switching transistor S in phase a arm aLeg1 and phase b arm bLeg1 a1 and S b1 The current waveform during fault-tolerant operation shows that bridge arms aLeg1 and bLeg1 are disconnected, leaving only bridge arms aLeg2, bLeg2, and phase c in operation. The inductor... L a1 and L b1 The current in the inductor is 0. L a2 and L b2 The current is equal to the grid current, while the inductance L c2 The current in the system is still half of the current fed into the grid.

[0094] like Figure 26 As shown, the switching transistor S in phase a bridge arm aLeg1 is shown. a1 In phase b bridge arm bLeg2, the switching transistor S b8 And the switching transistor S in phase c bridge arm cLeg1 c1 Current waveform diagram during fault-tolerant operation. At this time, phase a arm aLeg1, phase b arm bLeg2, and phase c arm cLeg1 are disconnected, and the inductance... L a2 and L c2 The current is equal to the grid current, and the inductance L b2 The current is 0, the switching transistors of the remaining bridge arms remain running, and the inductor... L a1 and L c1 The current will be 0, and the inductor L b1 The current will be equal to the grid current. Figure 27 For the switching transistor S in bridge arms aLeg1, bLeg1 and cLeg1 a1 S b1 S c1 The current waveform during fault-tolerant operation. At this time, bridge arms aLeg1, bLeg1, and cLeg1 are disconnected, while the switches of the remaining bridge arms remain operational. Therefore, the inductor... L a1 , L b1 and L c1 The current is 0, and the inductance is... L a2 , L b2 and L c2 The current is equal to the grid current at this time and when the converter is operating normally at rated half load.

[0095] like Figure 28 As shown, the switching transistor S in bridge arms aLeg1, bLeg1, and cLeg1 is... a1 S b1 S c1 and the switching transistor S in phase a bridge arm aLeg2 a10 The waveforms of the grid-connected current and inductor current during fault-tolerant operation. From Figure 28 As can be seen, aLeg1 and aLeg2 were not completely disconnected; instead, the fault switch S in aLeg1 was disconnected. a1 The half-bridge arm in question was cut off, and the faulty switch S in aLeg2 was removed. a4 The half-bridge arm in question is removed, leaving the healthy half-bridge arm. At this point, the a-phase inductance... La2 Since the current is a positive half-wave, it can be concluded that... L a1 The current will be a negative half-wave, and the inductor currents of phases b and c will equal the grid current, allowing the converter to continue operating. If the traditional fault-tolerant method of disconnecting the entire bridge arm is followed, the converter will be unable to maintain operation when such a fault occurs.

[0096] like Figure 29 As shown, the switching transistor S in bridge arms aLeg1, bLeg1, and cLeg1 is... a1 S b1 S c1 and the switching transistor S in aLeg2 and bLeg2 a10 S b10 Waveforms of grid-connected current and inductor current during fault-tolerant operation. From Figure 29 As can be seen from this, the inductor L a2 and L b2 The current is a sinusoidal positive half-wave, indicating that the faulty switch S a1 S b1 S c1 The half-bridge arm in question was removed, and the remaining healthy half-bridge arms are respectively controlled by the healthy switch S. a3 and S a4 Switch S b3 and S b4 Switch S c3 and S c4 Switch S a7 and S a8 and the switching transistor S b7 and S b8 The healthy half-bridge arm is formed by the inductance of phase C. L c2 The current is equal to the grid current, and the inductance L a1 and L b1 The current will be a sinusoidal negative half-wave, and the inductor L c1 The current will be 0, achieving fault-tolerant operation when all five switching transistors fail.

[0097] like Figure 30 As shown, the switching transistor S in bridge arms aLeg1, bLeg1, and cLeg1 is... a1 S b1 S c1 And the switching transistor S in aLeg2, bLeg2, and cLeg2 a10 S b10 S c10 The waveforms of the grid-connected current and inductor current during fault-tolerant operation. From Figure 30 As can be seen from this, the inductor L a2 , L b2 and L c2 If the current is a positive half-wave, then the inductor L a1 , L b1 and L c1 The current will be a negative half-wave, achieving fault tolerance in the event of a failure of the six switching transistors, allowing the converter to continue operating.

[0098] from Figures 22 to 30 It can be seen that if the fault-tolerant operation strategy of cutting off the entire bridge arm is adopted, some phases will be unable to maintain normal port voltage operation and will need to be shut down. However, by adopting the fault-tolerant operation strategy of cutting off half of the bridge arm proposed in this invention, the converter can continue to operate at half load power, realizing fault-tolerant operation in more scenarios.

[0099] In summary, the present invention provides a fault-tolerant operation method for a large-capacity offshore wind converter with multiple fault transistors, comprising at least two parallel A-NPC converters, each converter having the same structure, each phase consisting of two bridge arms connected in parallel, each bridge arm having two half-bridge arms and containing multiple switching transistors. The fault-tolerant control executes the following fault-tolerant strategy based on the number and location of the faulty switching transistors:

[0100] (1) When a single tube is open-circuited, the bridge arm containing the faulty switch tube is disconnected, and the healthy bridge arm continues to operate, and the system output power is reduced to half of the rated power;

[0101] (2) When there is a multi-tube open circuit fault, if the faulty switch tube is located in a different half-bridge arm of the same phase, the half-bridge arm where the faulty switch tube is located is cut off, and the remaining healthy half-bridge arm is used to reconstruct the split inductor bridge arm structure to maintain the output function of that phase.

[0102] (3) If the fault switch is located in the same half-bridge arm of different bridge arms in the same phase, and there is no redundant healthy half-bridge arm, it is determined to be fault-intolerant and the system shuts down.

[0103] (4) If the faulty switch tubes are distributed in different phases, they shall be handled in the manner of single tube fault combination, and the corresponding faulty bridge arm or half bridge arm shall be disconnected respectively.

[0104] (5) When the number of faulty switch tubes reaches 7 or more, the system is determined to be fault-intolerant and the shutdown protection is executed.

[0105] Example 2

[0106] This invention provides a high-capacity offshore wind converter multi-tube fault-tolerant operation system, applicable to an offshore wind power converter system with multiple converters of the same structure connected in parallel. The operation system includes:

[0107] The fault isolation module is configured to locate the faulty switch transistor, define the half-bridge arm with and without the faulty switch transistor as the faulty half-bridge arm and the healthy half-bridge arm, and block the drive signal of the faulty half-bridge arm.

[0108] The scenario judgment module is configured to determine whether the offshore wind power converter system is in a fault-tolerant operation scenario based on the positional relationship between the faulty half-arm and the healthy half-arm.

[0109] The fault-tolerant operation module is configured to reconstruct the faulty phase and restore its converter function by using a split inductor-type composite clamping bridge arm structure if the operation scenario is fault-tolerant.

[0110] Example 3

[0111] Based on the multi-transistor fault-tolerant operation method provided in Embodiment 1, this embodiment of the invention provides an electronic device, including a processor and a storage medium;

[0112] Storage media are used to store instructions;

[0113] The processor is used to perform operations according to instructions to execute the steps according to the method described above.

[0114] Example 4

[0115] Based on the multi-pipe fault-tolerant operation method provided in Embodiment 1, this embodiment of the invention provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the above method.

[0116] Example 5

[0117] Based on the multi-pipe fault-tolerant operation method provided in Embodiment 1, this embodiment of the invention provides a computer program product, including a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0118] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0119] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0120] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0121] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0122] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fault-tolerant operation method for a large-capacity offshore wind converter with multiple tubes, characterized in that, An operating method for an offshore wind power converter system in which multiple converters of the same structure are connected in parallel includes: Locate the faulty switch transistor, define the half-bridge arm with and without the faulty switch transistor as the faulty half-bridge arm and the healthy half-bridge arm, and shut down the drive signal of the faulty half-bridge arm. If all faulty half-bridge arms corresponding to all faulty switch tubes have healthy half-bridge arms at the same position, then the offshore wind power converter system is a fault-tolerant operating scenario. For fault-tolerant operating scenarios, a split inductor-type composite clamping bridge arm structure is used to reconstruct the faulty phase and restore its converter function, including: In the event of a single open-circuit fault, the bridge arm containing the faulty switch tube is disconnected, and the healthy bridge arm continues to operate, while the system output power is reduced to half of the rated power. In the event of a multi-tube open circuit fault, if the faulty switch is located in a half-bridge arm of a different bridge arm in the same phase, the half-bridge arm containing the faulty switch is cut off, and the remaining healthy half-bridge arm is used to reconstruct the split inductor bridge arm structure to maintain the output function of that phase; if the faulty switch is distributed in different phases, it is handled in the same way as a single-tube open circuit fault combination, and the corresponding faulty bridge arm or half-bridge arm is cut off respectively.

2. The fault-tolerant operation method for a large-capacity offshore wind converter with multiple tubes according to claim 1, characterized in that, If the number of fault switch transistors is 1, then there is only one faulty half-bridge arm, which has a healthy half-bridge arm in the same position, which is a fault-tolerant operation scenario.

3. The method for multi-tube fault-tolerant operation of a large-capacity offshore wind converter according to claim 1, characterized in that, If the number of fault switch tubes is 2, the two fault switch tubes belong to the same bridge arm and the same position half bridge arm, the same bridge arm and the opposite position half bridge arm, the same phase and the opposite bridge arm and the same position half bridge arm, the same phase and the opposite bridge arm and the opposite position half bridge arm, the opposite phase and the same bridge arm and the opposite position half bridge arm, the opposite phase and the opposite bridge arm and the opposite position half bridge arm, the opposite phase and the opposite bridge arm and the same position half bridge arm, or the opposite phase and the opposite bridge arm and the opposite position half bridge arm. If the number of parallel converters with the same structure in the offshore wind power converter system is 2, and they belong to the following categories: same-arm half-arm in the same position, same-arm half-arm in different position, same-phase half-arm half-arm in different position, different-arm half-arm in the same position, different-arm half-arm in different position, different-phase half-arm half-arm in different position, different-arm half-arm in the same position, or different-phase half-arm half-arm in different position, it is a fault-tolerant operation scenario; if they belong to the same-phase half-arm half-arm in the same position, it is a non-fault-tolerant operation scenario.

4. The fault-tolerant operation method for a large-capacity offshore wind converter with multiple tubes according to claim 3, characterized in that, If it belongs to the same phase but different bridge arm and different position half bridge arm, the fault phase reconstruction using the split inductor type composite clamping bridge arm structure includes: retaining the healthy half bridge arm in the two bridge arms corresponding to the fault switch tubes, and reconstructing the fault phase.

5. The method for multi-tube fault-tolerant operation of a large-capacity offshore wind converter according to claim 1, characterized in that, If the operation is not fault-tolerant, the offshore wind power converter system will be shut down for maintenance.

6. A multi-tube fault-tolerant operation system for a large-capacity offshore wind converter, characterized in that, An offshore wind power converter system applicable to multiple identical converters connected in parallel, the operating system includes: The fault isolation module is configured to locate the faulty switch transistor, define the half-bridge arm with and without the faulty switch transistor as the faulty half-bridge arm and the healthy half-bridge arm, and block the drive signal of the faulty half-bridge arm. The scenario judgment module is configured such that if all faulty half-bridge arms corresponding to all faulty switch tubes have healthy half-bridge arms at the same position, then the offshore wind power converter system is in a fault-tolerant operation scenario. The fault-tolerant operation module is configured to reconstruct the faulty phase and restore its converter function using a split inductor-type composite clamping bridge arm structure in fault-tolerant operation scenarios, including: In the event of a single open-circuit fault, the bridge arm containing the faulty switch tube is disconnected, and the healthy bridge arm continues to operate, while the system output power is reduced to half of the rated power. In the event of a multi-tube open circuit fault, if the faulty switch is located in a half-bridge arm of a different bridge arm in the same phase, the half-bridge arm containing the faulty switch is cut off, and the remaining healthy half-bridge arm is used to reconstruct the split inductor bridge arm structure to maintain the output function of that phase; if the faulty switch is distributed in different phases, it is handled in the same way as a single-tube open circuit fault combination, and the corresponding faulty bridge arm or half-bridge arm is cut off respectively.

7. An electronic device, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1-5.

9. A computer program product, comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method described in any one of claims 1-5.

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