Power generation system, wind power converter, grid-side converter and fault redundancy control method thereof

Abstract

The application provides a power generation system, a wind power converter, a grid-side converter and a fault redundancy control method thereof. In the control method, different preset short-circuit strategies and same power conversion strategies are preset in different preset control strategies, so that driving the grid-side converter with different preset control strategies each time is equivalent to trying which preset short-circuit strategy to make the AC side of the faulty DCAC conversion module short-circuited. In addition, on the basis that all the un-faulty DCAC conversion modules perform power conversion, if the output of the grid-side converter is a sine wave, the output of the grid-side converter can be restored, so that driving the grid-side converter with the current preset control strategy after starting operation of the grid-side converter can restore the output of the grid-side converter. In addition, since the control method does not replace the module device, the control method can restore the output of the grid-side converter without replacing the module device when the DCAC conversion module is faulty.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automatic control, in particular to a power generation system, a wind power converter, a grid-side converter and a fault redundancy control method thereof. BACKGROUND

[0002] At present, in a wind power generation system, the voltage level output by a wind turbine through a wind power converter is usually 690VAC or 1140VAC, and a high-voltage tank transformer is needed to transform the voltage, so that the power output by the wind turbine can be sent to the internal step-up system of the power station through a 10KV or 35KV power collection line, and finally the voltage can be lifted to 110KV through the step-up system and then be connected to the power grid.

[0003] Since the cost of the high-voltage tank transformer is high, in the grid-side converter of the wind power converter, the voltage level output by the grid-side converter can be improved by cascading the AC side of the DCAC conversion module, so that the power output by the wind power converter can be directly connected to the power collection line, thereby reducing the cost of the wind power generation system. However, as long as one of the DCAC conversion modules fails, a circuit is formed at the AC side of the module, which leads to the failure of the entire branch and the stop of the output of the entire grid-side converter.

[0004] Therefore, when a DCAC conversion module in the grid-side converter fails, how to restore the output of the grid-side converter without replacing the module device is a technical problem to be solved. SUMMARY

[0005] Therefore, the present application provides a power generation system, a wind power converter, a grid-side converter and a fault redundancy control method thereof, so as to restore the output of the grid-side converter without replacing the module device when a DCAC conversion module in the grid-side converter fails.

[0006] To achieve the above-mentioned purpose, the embodiments of the present application provide the following technical solutions:

[0007] The first aspect of the present application provides a fault redundancy control method of a grid-side converter, the grid-side converter comprising: at least two DCAC conversion modules cascaded in sequence at the AC side; the fault redundancy control method comprising:

[0008] After at least one DCAC conversion module fails, disconnecting the AC side of the grid-side converter;

[0009] driving the grid-side converter with different preset control strategies each time; the preset control strategies include a preset short-circuit strategy for all the faulty DCAC conversion modules and a power conversion strategy for all the non-faulty DCAC conversion modules, wherein the preset short-circuit strategies are different and the power conversion strategies are the same in the different preset control strategies;

[0010] after each driving, judging whether the output of the grid-side converter is a sine wave;

[0011] if the output of the grid-side converter is a sine wave, controlling the grid-side converter to start running and driving the grid-side converter with the current preset control strategy.

[0012] Optionally, before controlling the grid-side converter to start running, the method further comprises:

[0013] judging whether the output of the grid-side converter is a sine wave all the time within a preset time;

[0014] if the output of the grid-side converter is a sine wave all the time within the preset time, performing the step of controlling the grid-side converter to start running.

[0015] Optionally, before driving the grid-side converter with different preset control strategies each time, the method further comprises:

[0016] firstly lowering the DC-side voltage of each DCAC conversion module to zero;

[0017] secondly setting the DC-side voltage of each non-faulty DCAC conversion module to a preset value thereof; each preset value is less than or equal to the rated value of the corresponding DC-side voltage.

[0018] Optionally, before controlling the grid-side converter to start running, the method further comprises:

[0019] judging whether each DC-side voltage is equal to the rated value thereof;

[0020] if each DC-side voltage is not equal to the rated value thereof, increasing each DC-side voltage and returning to perform the step of judging whether each DC-side voltage is equal to the rated value thereof after driving the grid-side converter according to the current preset control strategy;

[0021] if each DC-side voltage is equal to the rated value thereof, performing the step of controlling the grid-side converter to start running.

[0022] Optionally, disconnecting the AC-side connection of the grid-side converter comprises:

[0023] controlling the grid-side converter to stop;

[0024] disconnecting the connection between the AC side of the grid-side converter and the load, and / or the connection between the AC side of the grid-side converter and the power grid.

[0025] Optionally, after disconnecting the AC side connection of the grid-side converter, further comprising:

[0026] connecting an analog load between the AC side of the grid-side converter;

[0027] Before controlling the grid-side converter to start operating, further comprising:

[0028] disconnecting the analog load from between the AC side of the grid-side converter.

[0029] Optionally, in the preset short-circuit strategy, the short-circuit strategy of the DCAC conversion module for each fault is included.

[0030] If the DCAC conversion module adopts an H-bridge inverter topology, in different preset short-circuit strategies, the different short-circuit strategies of the DCAC conversion module for the same fault include at least two of the following:

[0031] a short-circuit strategy of making two upper half-bridge arms of the DCAC conversion module of the corresponding fault conduct simultaneously and two lower half-bridge arms of the DCAC conversion module of the corresponding fault turn off simultaneously in a positive half output period, and making the two upper half-bridge arms conduct simultaneously and the two lower half-bridge arms turn off simultaneously in a negative half output period;

[0032] a short-circuit strategy of making two upper half-bridge arms of the DCAC conversion module of the corresponding fault conduct simultaneously and two lower half-bridge arms of the DCAC conversion module of the corresponding fault turn off simultaneously in a positive half output period, and making the two upper half-bridge arms turn off simultaneously and the two lower half-bridge arms conduct simultaneously in a negative half output period;

[0033] a short-circuit strategy of making two upper half-bridge arms of the DCAC conversion module of the corresponding fault turn off simultaneously and two lower half-bridge arms of the DCAC conversion module of the corresponding fault conduct simultaneously in a positive half output period, and making the two upper half-bridge arms conduct simultaneously and the two lower half-bridge arms turn off simultaneously in a negative half output period;

[0034] a short-circuit strategy of making two upper half-bridge arms of the DCAC conversion module of the corresponding fault turn off simultaneously and two lower half-bridge arms of the DCAC conversion module of the corresponding fault conduct simultaneously in a positive half output period, and making the two upper half-bridge arms turn off simultaneously and the two lower half-bridge arms conduct simultaneously in a negative half output period.

[0035] The second aspect of the present application provides a grid-side converter, comprising: a first switch, a controller, and at least two DCAC conversion modules; wherein:

[0036] The DC side of each DCAC conversion module is connected to the DC side of the grid-side converter.

[0037] The AC sides of the DCAC conversion modules are sequentially cascaded to form a cascade branch;

[0038] The first switch is arranged between one end of the cascade branch and a corresponding end of the AC side of the grid-side converter;

[0039] The first switch and each DCAC conversion module are controlled by the controller, and the controller is configured to perform the fault redundancy control method of the grid-side converter according to any one of the first aspect.

[0040] Optionally, the wind power converter further comprises at least two first DCDC conversion modules, wherein:

[0041] One side of each first DCDC conversion module is connected to a DC side of a corresponding DCAC conversion module;

[0042] The other side of each first DCDC conversion module is connected to a DC side of the grid-side converter;

[0043] Each first DCDC conversion module is controlled by the controller.

[0044] Optionally, the wind power converter further comprises a second switch and an analog load, wherein:

[0045] The second switch and the analog load are connected in series to form a series branch, and the series branch is connected between two ends of the AC side of the grid-side converter.

[0046] The second switch is controlled by the controller.

[0047] The third aspect of the present application provides a wind power converter, comprising at least one machine-side converter and at least one grid-side converter according to any one of the second aspect of the present application, wherein:

[0048] The AC side of each machine-side converter is connected to a corresponding wind turbine in one-to-one correspondence;

[0049] If the number of machine-side converters is greater than one, the DC side of each grid-side converter connected to the AC side is connected to a corresponding machine-side converter in one-to-one correspondence;

[0050] Alternatively,

[0051] If the number of machine-side converters is greater than one, the DC side of each machine-side converter is connected, and the connection point is connected to the DC side of at least one grid-side converter.

[0052] Optionally, the wind power converter further comprises at least one second DCDC conversion module, wherein:

[0053] One side of each second DCDC conversion module is connected to a DC side of a corresponding machine-side converter in one-to-one correspondence.

[0054] The other side of the second DCDC conversion module is connected to a photovoltaic string and / or an energy storage module.

[0055] Optionally, the system further comprises a system controller, wherein:

[0056] Each of the machine-side converters is controlled by the system controller, and the system controller is in communication connection with the controller in each of the grid-side converters.

[0057] The fourth aspect of the present application provides a power generation system, comprising at least one wind turbine generator, and a wind power converter as described in any one of the third aspects of the present application.

[0058] Optionally, if the wind power converter comprises at least one second DCDC conversion module, the power generation system further comprises at least one photovoltaic system and / or at least one energy storage system. According to the above technical solution, the present application provides a fault redundancy control method for a grid-side converter.

[0059] In the fault redundancy control method for the grid-side converter, since the preset short-circuit strategy is different and the power conversion strategy is the same in different preset control strategies, driving the grid-side converter with different preset control strategies each time is equivalent to trying which preset short-circuit strategy can make the AC side of the faulty DCAC conversion module short-circuited; and since on the basis that all the un-faulty DCAC conversion modules are performing power conversion, if the AC sides of all the faulty DCAC conversion modules are short-circuited, the grid-side converter will output a sine wave, so when it is judged that the output of the grid-side converter is a sine wave, it indicates that the current preset control strategy makes the AC sides of all the faulty DCAC conversion modules short-circuited, i.e. the output of the grid-side converter can be restored, therefore, the output of the grid-side converter is restored by controlling the grid-side converter to start running and driving the grid-side converter with the current preset control strategy; in addition, since the fault redundancy control method does not replace the module device, the fault redundancy control method for the grid-side converter provided by the present application can restore the output of the grid-side converter without replacing the module device when the DCAC conversion module in the grid-side converter fails. BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0061] Figure 1A flowchart of one embodiment of the fault redundancy control method of the grid-side converter provided by the embodiments of the present application;

[0062] Figure 2 A flowchart of the judging process of the circuit breaking fault;

[0063] Figures 3-6 A flowchart of another four embodiments of the fault redundancy control method of the grid-side converter provided by the embodiments of the present application;

[0064] Figures 7-9 Structural diagrams of three embodiments of the grid-side converter provided by the embodiments of the present application;

[0065] Figures 10-13 Structural diagrams of four embodiments of the power generation system provided by the embodiments of the present application. DETAILED DESCRIPTION

[0066] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0067] In the present application, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms “include”, “contain” or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement “including a…” does not exclude the presence of another identical element in the process, method, article or equipment including the element.

[0068] In order to temporarily restore the output of the grid-side converter when a fault occurs in the DCAC conversion module in the grid-side converter without replacing the module device, the embodiments of the present application provide a fault redundancy control method of a grid-side converter, and the specific structure of the grid-side converter can be referred to Figure 7 , which specifically includes: at least two DCAC conversion modules connected in series at the AC side.

[0069] Optionally, the DCAC conversion module can adopt, for example, Figure 7The H-bridge inverter topology shown can also adopt a three-level full-bridge inverter topology; in actual applications, including but not limited to this, as long as it is a full-bridge inverter topology, it is within the protection scope of the present application, and can be determined according to specific conditions, and is within the protection scope of the present application.

[0070] The fault redundancy control method of the grid-side converter will be described in detail below, and the specific process is as shown in Figure 1 The specific steps include the following steps:

[0071] S110, after the open-circuit fault of at least one DCAC conversion module, the AC side connection of the grid-side converter is disconnected.

[0072] In actual applications, after the open-circuit fault of the DCAC conversion module, that is, the open circuit is formed at the AC side of the DCAC conversion module, the AC side voltage of the DCAC conversion module becomes a large value, and the AC side current is approximately zero, so the open-circuit fault of the DCAC conversion module can be judged according to the change of the AC side voltage or the AC side current of the DCAC conversion module; taking the AC side voltage as an example, the judgment process of the open-circuit fault is specifically described, and the specific process is as shown in Figure 2 The specific steps include the following steps:

[0073] S210, judge whether the AC side voltage of the DCAC conversion module is greater than a preset voltage.

[0074] If the AC side voltage of the DCAC conversion module is greater than the preset voltage, step S220 is performed; if the AC side voltage of the DCAC conversion module is less than or equal to the preset voltage, step S230 is performed.

[0075] S220, determining that the DCAC conversion module has an open-circuit fault.

[0076] S230, determining that the DCAC conversion module has no open-circuit fault.

[0077] The above is only one embodiment of judging whether the DCAC conversion module has an open-circuit fault, and in actual applications, other embodiments are also included, which will not be described one by one here, and can be determined according to specific conditions.

[0078] In actual applications, the process of disconnecting the AC side connection of the grid-side converter is specifically: first, control the grid-side converter to stop, and then disconnect the connection between the AC side of the grid-side converter and the load, and / or the connection between the AC side of the grid-side converter and the power grid.

[0079] It should be noted that first controlling the grid-side converter to stop can avoid safety accidents caused by false touch and the like, thereby improving the power safety of the grid-side converter.

[0080] S120 drives the grid-side converter each time with a different preset control strategy.

[0081] The preset control strategies include a preset short-circuit strategy for all faulty DCAC converter modules and a power conversion strategy for all fault-free DCAC converter modules. In practical applications, driving all faulty DCAC converter modules with the preset short-circuit strategy is equivalent to controlling both ends of the AC side of all faulty DCAC converter modules to be short-circuited. Driving all fault-free DCAC converter modules with the power conversion strategy is equivalent to controlling all fault-free DCAC converter modules to perform power conversion. It should be noted that the power conversion strategy is the same as that in the prior art, and will not be described in detail here.

[0082] In addition, the preset short-circuit strategy differs among different preset control strategies, while the power conversion strategy remains the same.

[0083] The preset short-circuit strategy is a predicted strategy that can short-circuit both ends of the AC side of each faulty DCAC converter module. That is, the preset short-circuit strategy includes a short-circuit strategy for each faulty DCAC converter module. Typically, the preset short-circuit strategy is preset based on the specific topology of the DCAC converter module and the predicted cause of the open-circuit fault in each DCAC converter module.

[0084] The DC-AC conversion module adopts Figure 7 Taking the H-bridge inverter topology shown as an example, under different preset short-circuit strategies, the different short-circuit strategies for the same fault in the DC-AC converter module include at least the following two:

[0085] 1. A short-circuit strategy that, during the positive half-output cycle, simultaneously turns on the two upper half-bridge arms and simultaneously turns off the two lower half-bridge arms in the corresponding faulty DCAC converter module, and during the negative half-output cycle, simultaneously turns on the two upper half-bridge arms and simultaneously turns off the two lower half-bridge arms in the corresponding faulty DCAC converter module.

[0086] 2. A short-circuit strategy that, during the positive half-output cycle, simultaneously turns on the two upper half-bridge arms and simultaneously turns off the two lower half-bridge arms in the corresponding faulty DCAC converter module, and during the negative half-output cycle, simultaneously turns off the two upper half-bridge arms and simultaneously turns on the two lower half-bridge arms in the corresponding faulty DCAC converter module.

[0087] 3. A short-circuit strategy that, during the positive half-output cycle, simultaneously turns off the two upper half-bridge arms and simultaneously turns on the two lower half-bridge arms in the corresponding faulty DCAC converter module, and during the negative half-output cycle, simultaneously turns on the two upper half-bridge arms and simultaneously turns off the two lower half-bridge arms in the corresponding faulty DCAC converter module.

[0088] 4. In the positive half output cycle, the two upper half bridge arms in the DCAC conversion module corresponding to the fault are turned off at the same time, and the two lower half bridge arms are turned on at the same time; in the negative half output cycle, the two upper half bridge arms in the DCAC conversion module corresponding to the fault are turned off at the same time, and the two lower half bridge arms are turned on at the same time.

[0089] In different preset short circuit strategies, different short circuit strategies of the DCAC conversion module for the same fault include four short circuit strategies, for example, if the number of the fault DCAC conversion module is equal to 1, the different preset short circuit strategies are as shown in the following table:

[0090] Serial number Positive half output cycle Negative half output cycle 1 Q1 and Q2 on, Q3 and Q4 off Q1 and Q2 on, Q3 and Q4 off 2 Q1 and Q2 on, Q3 and Q4 off Q1 and Q2 off, Q3 and Q4 on 3 Q1 and Q2 off, Q3 and Q4 on Q1 and Q2 on, Q3 and Q4 off 4 Q1 and Q2 off, Q3 and Q4 on Q1 and Q2 off, Q3 and Q4 on

[0091] Q1 and Q2 in the table are the switch tubes in the two upper half bridge arms, Q1 and Q2 are turned on, that is, the two upper half bridge arms are turned on; Q3 and Q4 are the switch tubes in the two lower half bridge arms, Q3 and Q4 are turned on, that is, the two lower half bridge arms are turned on.

[0092] If the number of the fault DCAC conversion module is equal to 2, assuming that G1 and G2 have open circuit faults, the different preset short circuit strategies are as shown in the following table:

[0093]

[0094]

[0095] Q1, Q2, Q3 and Q4 in the table refer to the same as in the above table, which will not be repeated here.

[0096] It should be noted that since in step S120, the preset short circuit strategy is required to drive all fault DCAC conversion modules each time, after all preset short circuit strategies are executed, the execution of the fault redundancy control method of the grid-side converter is stopped.

[0097] S130, after each driving, it is judged whether the output of the grid-side converter is a sine wave.

[0098] If the output of the grid-side converter is a sine wave, step S140 is executed; if the output of the grid-side converter is not a sine wave, step S120 is returned to be executed.

[0099] In actual application, the output of the grid-side converter can be current or voltage, which is not limited here, and depends on the output control mode of the grid-side converter, for example, if it is open loop control, the output of the grid-side converter is voltage, if it is closed loop control, the output of the grid-side converter is current.

[0100] Since the non-faulty DCAC conversion modules do not fail, when all the non-faulty DCAC conversion modules are driven in the power conversion strategy, all the non-faulty DCAC conversion modules perform power conversion, that is, the outputs of each non-faulty DCAC conversion module are sine waves.

[0101] In addition, since on the basis that all the non-faulty DCAC conversion modules perform power conversion, if the AC sides of all the faulty DCAC conversion modules are short-circuited, the grid-side converter outputs sine waves, therefore, when it is judged that the output of the grid-side converter is a sine wave, it indicates that the current preset control strategy causes the AC sides of all the faulty DCAC conversion modules to be short-circuited, that is, the output of the grid-side converter can be restored.

[0102] S140, control the grid-side converter to start running and drive the grid-side converter in the current preset control strategy.

[0103] The current preset control strategy refers to the preset control strategy executed when it is judged that the output of the grid-side converter is a sine wave.

[0104] Since the preset short-circuit strategy is different and the power conversion strategy is the same in different preset control strategies, driving the grid-side converter in different preset control strategies each time is equivalent to trying which preset short-circuit strategy can cause the AC sides of the faulty DCAC conversion modules to be short-circuited; in addition, as known from the above, when it is judged that the output of the grid-side converter is a sine wave, it indicates that the current preset control strategy causes the AC sides of all the faulty DCAC conversion modules to be short-circuited, that is, the output of the grid-side converter can be restored, therefore, the output of the grid-side converter is restored by controlling the grid-side converter to start running and driving the grid-side converter in the current preset control strategy; in addition, since the fault redundancy control method does not replace the module device, the fault redundancy control method of the grid-side converter provided in the present application can restore the output of the grid-side converter without replacing the module device when the DCAC conversion modules in the grid-side converter fail.

[0105] It should be noted that in actual application, the preset short-circuit strategy cannot cause all the faulty DCAC conversion modules to be short-circuited in any case, for example, taking the case where one DCAC conversion module fails and the DCDC conversion module adopts an H-bridge inverter topology as an example, if Q1, Q3 and the anti-parallel diodes thereof all fail, the preset short-circuit strategy cannot cause the AC side of the DCAC conversion module to be short-circuited, that is, the grid-side converter cannot restore the output at this time, therefore, the fault redundancy control method of the grid-side converter provided in the present application can only restore the AC side output of the grid-side converter in a specific case when the DCAC conversion modules in the grid-side converter fail.

[0106] In actual application, when the AC side of the faulty DCAC conversion module forms a short circuit, the short circuit path between the AC side of the faulty DCAC conversion module can not be able to withstand the large current for a long time, and thus the open circuit between the AC side of the DCAC conversion module can be formed again after the output is restored. In order to solve the problem, another embodiment of the application provides another implementation of the fault redundancy control method of the grid-side converter, and the specific structure is shown in Figure 3 The embodiment is based on the above-mentioned embodiment, and further includes the following steps before step S140:

[0107] S310, determining whether the output of the grid-side converter is always a sine wave within a preset time.

[0108] If the output of the grid-side converter is always a sine wave within the preset time, step S140 is performed; if the output of the grid-side converter is not always a sine wave within the preset time, step S120 is performed.

[0109] The preset time is a time set in advance according to experience and actual situation, which is not limited here.

[0110] In the embodiment, whether the short circuit path between the AC side of the faulty DCAC conversion module can withstand the current for a long time is tested through step S310, and thus the problem that the open circuit between the AC side of the DCAC conversion module is formed again after the output is restored can be solved.

[0111] Another embodiment of the application provides another implementation of the fault redundancy control method of the grid-side converter, and the specific process can be referred to Figure 4 (based on only Figure 1 ), which is based on the above-mentioned embodiment, and further includes the following steps before step S120:

[0112] S410, reducing the DC voltage of each DCAC conversion module to zero.

[0113] As described above, the faulty DCAC conversion module cannot perform power conversion, and thus the DC voltage of the faulty DCAC conversion module can be reduced to zero.

[0114] S420, setting the DC voltage of each non-faulty DCAC conversion module to a preset value.

[0115] Each preset value is less than or equal to the rated value of the DC voltage of the corresponding DCAC conversion module.

[0116] If the DC side of the DCAC conversion module is connected to the DCDC conversion module, as shown in Figure 8 or Figure 9If so, step S420 is performed, specifically: establishing voltage at the input side of the DCDC, and controlling the DCDC conversion module to output preset voltage.

[0117] The embodiment also provides another implementation of the method for fault redundancy control of the grid-side converter. Figure 5 As shown in the figure, this implementation is based on the previous implementation and further includes the following steps before step S140:

[0118] S510: determining whether the DC voltage of each non-faulty DCAC conversion module is equal to the respective rated value.

[0119] If the DC voltage of each non-faulty DCAC conversion module is not equal to the respective rated value, steps S520 and S530 are sequentially performed, and after step S530, step S510 is performed again; if the DC voltage of each DCAC conversion module is equal to the respective rated value, step S140 is performed.

[0120] S520: increasing the DC voltage of each non-faulty DCAC conversion module.

[0121] S530: driving the grid-side converter according to the current preset control strategy.

[0122] In this implementation, the driving mode that can stabilize the output of the grid-side converter is determined when the DC voltage of the non-faulty DCAC conversion module is set to a lower value; then, the DC voltage of the non-faulty DCAC conversion module is gradually increased, so that the current borne by the short-circuit path between the two ends of the AC side of the faulty DCAC conversion module gradually increases, thereby avoiding secondary damage to the grid-side converter.

[0123] Another embodiment of the method for fault redundancy control of the grid-side converter is provided, and the specific process can be referred to Figure 6 (only on the basis of Figure 1 ), which is based on the above-mentioned implementation and further includes the following steps after step S110:

[0124] S610: connecting an analog load between the two ends of the AC side of the grid-side converter.

[0125] The analog load is used to simulate the real load, which can be an inductor, a resistor, or other impedance devices, or even a combination of different impedance devices, which are not limited in the present application.

[0126] Before step S140, the following steps are further included:

[0127] S620, cut off the analog load from between the AC side of the grid-side converter.

[0128] Another embodiment of the present application provides a grid-side converter, the specific structure of which can be seen from Figure 7 (4 DCAC conversion modules G1-G4 are taken as an example for illustration), and specifically comprises a first switch S1, a controller (not shown in the simplified view), and at least two DCAC conversion modules G1-Gn.

[0129] The DC side of each DCAC conversion module is connected to the DC side of the grid-side converter; and the AC side of each DCAC conversion module is sequentially cascaded, with the first end of the AC side of the first DCAC conversion module serving as the first end of the AC side of the grid-side converter, and the second end of the AC side of the last DCAC conversion module serving as the second end of the AC side of the grid-side converter.

[0130] The first switch S1 is arranged between the first end of the AC side of the first DCAC conversion module and the first end of the AC side of the grid-side converter, and / or between the second end of the AC side of the last DCAC conversion module and the second end of the AC side of the grid-side converter.

[0131] Each DCAC conversion module and the first switch S1 are controlled by the controller, and the controller is configured to perform the fault redundancy control method of the grid-side converter provided in the above embodiment.

[0132] The embodiment further provides another implementation of the grid-side converter, the specific structure of which can be seen from Figure 8 (illustrated on the basis of Figure 7 ), and the implementation further comprises at least two first DCDC conversion modules on the basis of the above implementation.

[0133] One side of each first DCDC conversion module is connected to the DC side of a corresponding first DCAC conversion module; the other side of each first DCDC conversion module is connected to the DC side of the grid-side converter; and each first DCDC conversion module is controlled by the controller.

[0134] The embodiment further provides still another implementation of the grid-side converter, the specific structure of which can be seen from Figure 9 (illustrated on the basis of Figure 8 ), and the implementation further comprises a second switch S2 and an analog load 10 on the basis of the above implementation.

[0135] The second switch S2 and the analog load 10 are connected in series to form a series branch, and the series branch is connected between the two ends of the AC side of the grid-side converter.

[0136] Another embodiment of the present application provides a wind power conversion device, the specific structure of which can be seen from Figure 10 orFigure 11 , and specifically comprises at least one machine-side converter 100 and at least one grid-side converter 200 provided in the above embodiments.

[0137] The AC side of each machine-side converter 100 is connected to a wind turbine generator 300 in one-to-one correspondence.

[0138] If the number of machine-side converters 100 is equal to 1, the DC side of the machine-side converter 100 is connected to the DC side of at least one grid-side converter 200, and the AC side of each grid-side converter 200 serves as a grid-side interface of the grid-side converter.

[0139] The present embodiment provides two implementation modes between the machine-side converter 100 and the grid-side converter 200, which are applicable to the case where the number of machine-side converters 100 is greater than 1, and are described as follows:

[0140] The first implementation mode is a distributed structure, which can be seen from Figure 10 , and specifically, the DC side of each grid-side converter 200 connected to the AC side is connected to the corresponding machine-side converter 100, and the connection point between the grid-side converters 200 connected to the AC side serves as the corresponding grid-side interface of the grid-side converter.

[0141] The second implementation mode is a centralized structure, which can be seen from Figure 11 , and specifically, the DC side of each machine-side converter 100 is connected, and the connection point is connected to the DC side of at least one grid-side converter 200.

[0142] When the DC side of the machine-side converter 100 is connected to the DC side of three grid-side converters 200, if the AC side output of the three grid-side converters 200 is 120 degrees apart in phase, the AC side output of the three grid-side converters 200 is three-phase AC power.

[0143] The present embodiment also provides another implementation mode of the wind power conversion device, and the specific structure can be seen from Figure 12 (based on Figure 10 , taking a photovoltaic string 500 and an energy storage module 600 as an example for display) or Figure 12 (based on Figure 11 , taking a photovoltaic string 500 and an energy storage module 600 as an example for display), and on the basis of the above implementation mode, the present implementation mode further comprises at least one second DC / DC conversion module 400.

[0144] One side of each second DC / DC conversion module 400 is connected to the DC side of the corresponding machine-side converter 100, and the other side of the second DC / DC conversion module 400 is connected to the photovoltaic string 500 and / or the energy storage module 600.

[0145] The embodiment further provides another implementation of the wind power conversion device, and the implementation further comprises a system controller based on the implementation.

[0146] Each of the machine-side converters 100 is controlled by the system controller; in actual application, the system controller and the controllers in the grid-side converters 200 are independently arranged, and the system controller is in communication connection with the controllers in the grid-side converters 200; of course, the controllers in the grid-side converters 200 can also be integrated in the system controller; here, no specific limitation is made, and the specific condition can be determined, and all falls within the protection scope of the application.

[0147] In actual application, in addition to that the machine-side converters 100 are included in the wind power conversion device, the machine-side converters 100 can also be integrated in the corresponding wind turbine 300; here, no specific limitation is made, and the specific condition can be determined, and all falls within the protection scope of the application.

[0148] Another embodiment of the application provides a power generation system, and the specific structure can be referred to Figure 10 or Figure 11 , and specifically comprises at least one wind turbine 300 and the wind power conversion device provided in the above embodiment.

[0149] It should be noted that the connection relationship between the wind turbine 300 and the wind power conversion device has been described in detail in the above embodiment, and will not be repeated here.

[0150] If the wind power conversion device comprises at least one second DCDC conversion module, the specific structure of the power generation system can be referred to Figure 12 or Figure 13 , and further comprises at least one photovoltaic system and / or at least one energy storage system.

[0151] It should be noted that the connection relationship between the photovoltaic system, the energy storage system and the wind power conversion device has been described in detail in the above embodiment, and will not be repeated here.

[0152] The above description of the disclosed embodiments is merely exemplary and not limiting. Since modifications and changes can be made to the disclosed embodiments without departing from the spirit and scope of the application, it is intended that such modifications and changes be included within the scope of the application as defined in the claims.

Claims

1. A method for failure redundancy control of a grid-side converter, characterized by, The grid-side converter comprises at least two DCAC conversion modules connected in series on the AC side; the fault redundancy control method comprises: After a circuit breaking fault occurs in at least one DCAC conversion module, disconnecting the AC side connection of the grid-side converter; Driving the grid-side converter with different preset control strategies each time; the preset control strategies comprise a preset short circuit strategy for all faulty DCAC conversion modules and a power conversion strategy for all non-faulty DCAC conversion modules, wherein the preset short circuit strategies are different and the power conversion strategies are the same in different preset control strategies; After each driving, judging whether the output of the grid-side converter is a sine wave; If the output of the grid-side converter is a sine wave, controlling the grid-side converter to start running and driving the grid-side converter with the current preset control strategy.

2. The method of fault redundant control of a grid-side converter according to claim 1, characterized in that, Before controlling the grid-side converter to start running, further comprising: Judging whether the output of the grid-side converter is always a sine wave within a preset time; If the output of the grid-side converter is always a sine wave within the preset time, performing the step of controlling the grid-side converter to start running.

3. The method of fault redundant control of a grid-side converter according to claim 1 or 2, characterized in that, Before driving the grid-side converter with different preset control strategies each time, further comprising: Firstly, reducing the DC side voltage of each DCAC conversion module to zero; Then, setting the DC side voltage of each non-faulty DCAC conversion module to a respective preset value; each preset value is less than or equal to the rated value of the corresponding DC side voltage.

4. The method of fault redundant control of a grid-side converter according to claim 3, characterized in that, Before controlling the grid-side converter to start running, further comprising: Judging whether the DC side voltage of each non-faulty DCAC conversion module is equal to the respective rated value; If the DC side voltage of each non-faulty DCAC conversion module is not equal to the respective rated value, increasing the DC side voltage of each non-faulty DCAC conversion module, and after driving the grid-side converter according to the current preset control strategy, returning to perform the step of judging whether the DC side voltage of each non-faulty DCAC conversion module is equal to the respective rated value; If the DC side voltage of each non-faulty DCAC conversion module is equal to the respective rated value, performing the step of controlling the grid-side converter to start running.

5. The method of fault redundant control of a grid-side converter according to claim 1 or 2, characterized in that, Disconnecting the AC side connection of the grid-side converter comprises: Controlling the grid-side converter to stop running; Disconnecting the connection between the AC side of the grid-side converter and the load and / or the connection between the AC side of the grid-side converter and the power grid.

6. The method of fault redundant control of a grid-side converter according to claim 1 or 2, characterized in that, After disconnecting the AC side connection of the grid-side converter, further comprising: Connecting an analog load between the two ends of the AC side of the grid-side converter; Before controlling the grid-side converter to start running, further comprising: Cutting off the analog load from between the two ends of the AC side of the grid-side converter.

7. The method of fault redundant control of a grid-side converter according to claim 1 or 2, characterized in that, In the preset short circuit strategy, a short circuit strategy for each faulty DCAC conversion module is included; If the DCAC conversion module adopts an H-bridge inverter topology, in different preset short circuit strategies, different short circuit strategies for the same faulty DCAC conversion module comprise at least two of the following: a short-circuit strategy of making two upper half-bridge arms in the DCAC conversion module of the corresponding fault conduct simultaneously and two lower half-bridge arms cut off simultaneously in the positive half output period, and making two upper half-bridge arms conduct simultaneously and two lower half-bridge arms cut off simultaneously in the negative half output period; a short-circuit strategy of making two upper half-bridge arms cut off simultaneously and two lower half-bridge arms conduct simultaneously in the positive half output period, and making two upper half-bridge arms conduct simultaneously and two lower half-bridge arms cut off simultaneously in the negative half output period; a short-circuit strategy of making two upper half-bridge arms cut off simultaneously and two lower half-bridge arms conduct simultaneously in the positive half output period, and making two upper half-bridge arms conduct simultaneously and two lower half-bridge arms cut off simultaneously in the negative half output period; a short-circuit strategy of making two upper half-bridge arms cut off simultaneously and two lower half-bridge arms conduct simultaneously in the positive half output period, and making two upper half-bridge arms conduct simultaneously and two lower half-bridge arms cut off simultaneously in the negative half output period.

8. A grid-side converter, characterized by comprising: a first switch, a controller and at least two DCAC conversion modules; wherein: the DC side of each DCAC conversion module is connected to the DC side of the grid-side converter; the AC side of each DCAC conversion module is sequentially cascaded to form a cascade branch; the first switch is arranged between one end of the cascade branch and the corresponding end of the AC side of the grid-side converter; the first switch and each DCAC conversion module are controlled by the controller, and the controller is configured to execute the fault redundancy control method of the grid-side converter according to any one of claims 1 to 7.

9. The grid-side converter of claim 8, wherein, further comprising: at least two first DCDC conversion modules; wherein: one side of each first DCDC conversion module is connected to the DC side of a corresponding DCAC conversion module; the other side of each first DCDC conversion module is connected to the DC side of the grid-side converter; each first DCDC conversion module is controlled by the controller.

10. The grid-side converter according to claim 8 or 9, characterized in that further comprising: a second switch and an analog load; wherein: the series branch formed by the series connection of the second switch and the analog load is connected between the two ends of the AC side of the grid-side converter; the second switch is controlled by the controller.

11. A wind power converter, characterized in that comprising: at least one machine-side converter and at least one grid-side converter according to any one of claims 8 to 10; wherein: the AC side of each machine-side converter is connected to a corresponding wind turbine generator; if the number of machine-side converters is greater than 1, the DC side of each grid-side converter connected to the AC side is connected to a corresponding machine-side converter; or, if the number of machine-side converters is greater than 1, the DC side of each machine-side converter is connected, and the connection point is connected to the DC side of at least one grid-side converter.

12. The wind power conversion device of claim 11, wherein, further comprising: at least one second DCDC conversion module; wherein: one side of each second DCDC conversion module is connected to the DC side of a corresponding machine-side converter; the other side of each second DCDC conversion module is connected to a photovoltaic string and / or an energy storage module.

13. The wind power conversion device according to claim 11 or 12, characterized in that, further comprising: a system controller; wherein: Each of the machine-side converters is controlled by the system controller, which is communicatively connected to the controllers in each of the grid-side converters.

14. A power generation system characterized by comprising: Comprising: at least one wind turbine and a wind power converter as claimed in any of claims 11 to 13.

15. The power generation system of claim 14, wherein, If the wind power converter comprises at least one second DC / DC conversion module, the power generation system further comprises at least one photovoltaic system and / or at least one energy storage system.

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