Wind power converter and closed-loop test method thereof

Abstract

The application provides a wind power converter and a closed-loop test method thereof. In the closed-loop test method, the grid-side converter forms a loop with the grid-side filter capacitor connected to the AC side of the grid-side converter, the machine-side converter forms a loop with the generator connected to the AC side of the machine-side converter, and the slow start circuit in the wind power converter is used to charge the DC bus capacitor in the wind power converter. Therefore, the closed-loop test method no longer needs field staff to complete the preparation work before the fault detection of the two converters, thereby reducing the risk of high-voltage contact faced by the field staff when the two converters in the wind power converter are subjected to fault detection.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a wind power converter and its closed-loop testing method. Background Technology

[0002] During the operation of wind power converters, various faults may occur, the most common of which is the failure of power modules. Typically, the failure of power modules often leads to the failure of components in other circuits. For example, the failure of one phase power module may indirectly cause different degrees of failure in other phase power modules. Therefore, after replacing the failed power module, it is necessary to perform fault detection on the two converters in the wind power converter.

[0003] However, the preparation work for fault detection of the two converters currently needs to be completed by on-site personnel, which exposes them to the risk of contact with high voltage, thus making it easy for safety accidents to occur.

[0004] Therefore, how to reduce the risk of high-voltage contact faced by on-site personnel when performing fault detection on the two converters in the wind power converter is an urgent technical problem to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a wind power converter and its closed-loop testing method to reduce the risk of high voltage contact faced by on-site personnel when performing fault detection on the two converters in the wind power converter.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] This application provides a closed-loop testing method for wind power converters, including:

[0008] The soft-start circuit in the wind power converter is controlled to draw power from the grid side of the wind power converter to charge the DC bus capacitor in the wind power converter.

[0009] After the bus voltage of the DC bus capacitor stabilizes, the corresponding converters are tested for faults in stages using the circuits formed by the grid-side converter and the grid-side filter capacitor in the wind power converter, and the circuits formed by the generator-side converter and the generator in the wind power converter.

[0010] Optionally, a fault detection of the converter can be performed using a loop formed by the converter, including:

[0011] Control the converter to perform inversion so that the output electrical parameters of each phase on its AC side are equal to the set electrical parameters;

[0012] When it is detected that the output electrical parameters of at least one phase on the AC side of the converter are inconsistent with the set electrical parameters, the converter is reported to have a fault, and the power module in the converter that is faulty is also reported.

[0013] Optionally, the converter can be controlled to perform inversion, so that the output electrical parameters of each phase on its AC side are equal to the set electrical parameters, including:

[0014] The converter is controlled to perform inversion, so that the output electrical parameters of each phase on its AC side are gradually increased to the set electrical parameters.

[0015] Optional output electrical parameters include: output current, or output voltage.

[0016] Optionally, the set electrical parameters are less than or equal to the maximum output electrical parameters on the AC side of the converter.

[0017] Optionally, if the output electrical parameter is the output current, then the effective value of the maximum output electrical parameter on the AC side of the converter is equal to the product of a preset coefficient and the bus voltage of the DC bus capacitor, and the ratio of the equivalent total impedance of the circuit formed by the converter.

[0018] Optionally, in addition to controlling the converter to perform inversion, it also includes:

[0019] Control another converter to block the wave.

[0020] Optionally, fault detection is performed on the two converters in stages, including:

[0021] Fault detection is performed on the grid-side converter;

[0022] When there is no fault in the grid-side converter, fault detection is performed on the machine-side converter;

[0023] When there is no fault in the generator-side converter, the wind power converter is controlled to operate in grid-connected mode.

[0024] Optionally, when a fault occurs in the grid-side converter or the machine-side converter, the following further applies:

[0025] Control the corresponding converter to stop inverting, and control the soft-start circuit to stop charging.

[0026] Optionally, if a filter capacitor switch is provided between the AC side of the grid-side converter and the grid-side filter capacitor, then before performing fault detection on the grid-side converter, the following method is also included:

[0027] Control the closing of the filter capacitor switch;

[0028] Before performing fault detection on the machine-side converter, the following is also included:

[0029] The filter capacitor switch is turned off.

[0030] This application also provides a wind power converter, comprising: a stator switch, a frame switch, a DC bus capacitor, a grid-side converter, a machine-side converter, a grid-side filter capacitor, a soft-start circuit, and a controller; wherein:

[0031] The AC side of the machine-side converter is connected to the rotor of the generator;

[0032] The DC side of the machine-side converter is connected to the DC side of the grid-side converter via a DC bus, and the DC bus capacitor is connected between the positive DC bus and the negative DC bus.

[0033] The AC side of the grid-side converter is connected to the grid-side filter capacitor, and the connection point is connected to the power grid through the frame switch.

[0034] The AC side of the grid-side converter is also connected to the first terminal of the stator switch, and the second terminal of the stator switch is connected to the stator of the generator;

[0035] The AC side of the slow-start circuit draws power from the power grid, and the DC side of the slow-start circuit is connected to the DC bus.

[0036] The stator switch, frame switch, two converters, and soft-start circuit are all controlled by the controller, which is used to execute the closed-loop test method for the wind power converter as described in any of the preceding aspects of this application.

[0037] Optionally, the soft-start circuit includes: a boost rectifier unit and a soft-start switch connected in series;

[0038] Both the boost rectifier unit and the soft-start switch are controlled by the controller.

[0039] Optionally, the boost rectifier unit is a Boost boost rectifier unit.

[0040] Optionally, it also includes: a filter capacitor switch; wherein:

[0041] The filter capacitor switch is located between the grid-side filter capacitor and the AC side of the grid-side converter;

[0042] The filter capacitor switch is controlled by the controller.

[0043] Optionally, the power module in the converter can be a three-level topology or a two-level topology.

[0044] Optionally, it also includes: at least two electrical parameter sensors; wherein:

[0045] Each phase of the AC side of the machine-side converter and each phase of the AC side of the grid-side converter are equipped with an electrical parameter sensor. The electrical parameter sensor is used to collect the output electrical parameters of each phase of the AC side of the machine-side converter and the output electrical parameters of each phase of the AC side of the grid-side converter.

[0046] The electrical parameter sensor is communicatively connected to the controller.

[0047] Optionally, it may also include at least one of the following: a grid-side filter inductor, a machine-side filter inductor, a machine-side filter capacitor, and a stator filter capacitor; wherein:

[0048] The grid-side filter inductor is disposed between the AC side of the grid-side converter and the first terminal of the stator switch;

[0049] The machine-side filter inductor is disposed between the AC side of the machine-side converter and the rotor;

[0050] The machine-side filter capacitor is connected to the AC side of the machine-side converter;

[0051] The stator filter capacitor is connected to the stator.

[0052] As can be seen from the above technical solution, the present invention provides a closed-loop testing method for wind power converters. In this closed-loop testing method, since the grid-side converter forms a loop using the grid-side filter capacitor connected to its own AC side, and the generator-side converter forms a loop using the generator connected to its own AC side, and furthermore, the DC bus capacitor in the wind power converter is charged using the soft-start circuit in the wind power converter, this closed-loop testing method no longer requires on-site personnel to complete the preparatory work before fault detection of the two converters. Therefore, it reduces the high-voltage contact risk faced by on-site personnel when performing fault detection on the two converters in the wind power converter. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0054] Figure 1 and Figure 2 These are schematic flowcharts illustrating two implementation methods of the closed-loop testing method for wind power converters provided in this application.

[0055] Figure 3 and Figure 4These are schematic flowcharts illustrating two implementation methods for fault detection of a converter using a circuit formed by a converter, as provided in the embodiments of this application.

[0056] Figure 5 A flowchart illustrating another implementation of the closed-loop testing method for wind power converters provided in this application embodiment;

[0057] Figures 6-9 These are schematic diagrams illustrating four implementations of the wind power converter provided in this application. Detailed Implementation

[0058] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0059] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] To reduce the risk of high-voltage contact for on-site personnel when performing fault detection on the two converters in a wind power converter, this application provides a closed-loop testing method for wind power converters.

[0061] The wind power converter includes: a stator switch, a frame switch, a DC bus capacitor, a grid-side converter, a generator-side converter, a grid-side filter capacitor, and a soft-start circuit. The AC side of the generator-side converter is connected to the input side of the generator rotor, and the DC side of the generator-side converter is connected to the DC side of the grid-side converter via a DC bus. The DC bus capacitor is connected between the positive and negative DC buses. The AC side of the grid-side converter is connected to the grid-side filter capacitor, and the connection point is connected to the power grid via the frame switch. The AC side of the grid-side converter is also connected to the first terminal of the stator switch, and the second terminal of the stator switch is connected to the stator of the generator. The AC side of the soft-start circuit is connected to the power grid, and the DC side of the soft-start circuit is connected to the DC bus.

[0062] In practical applications, this closed-loop testing method can be performed after the faulty power module in the wind power converter has been replaced, or it can be performed before the normal wind power converter is connected to the grid. There is no specific limitation here, and it can be performed depending on the specific situation. All of these are within the protection scope of this application.

[0063] It should be noted that, regardless of which of the two situations described above is the closed-loop test method executed, the wind power converter is in a shutdown state when the closed-loop test method is executed, that is: the stator switch and frame switch are both in the open state, and the machine-side converter, grid-side converter, and soft-start circuit are all in an inactive state.

[0064] The specific process of this closed-loop testing method is as follows: Figure 1 As shown, the specific steps include:

[0065] S110 controls the slow-start circuit in the wind power converter to draw power from the grid side of the wind power converter to charge the DC bus capacitor in the wind power converter.

[0066] Since the soft-start circuit in a wind power converter can convert AC to DC, this closed-loop test method can control the soft-start circuit to draw power from the grid side of the wind power converter to charge the DC bus capacitor.

[0067] In practical applications, the bus voltage of the DC bus capacitor is less than or equal to the voltage across the DC bus capacitor when the wind power converter is connected to the grid. No specific limit is set here, and it can be determined according to the specific situation.

[0068] Ideally, the bus voltage of the DC bus capacitor should be equal to the voltage across the DC bus capacitor when the wind power converter is connected to the grid. This not only allows testing for faults in each phase power module, but also for testing whether each phase power module can operate normally during grid connection.

[0069] S120. After the bus voltage of the DC bus capacitor stabilizes, the corresponding converters are tested for faults in stages using the circuits formed by the grid-side converter and the grid-side filter capacitor in the wind power converter, and the circuits formed by the generator-side converter and the generator in the wind power converter.

[0070] That is, the grid-side converter is used once to detect faults in the grid-side converter through a loop formed by the grid-side converter and the grid-side filter capacitor, and the generator-side converter is used once to detect faults in the generator-side converter through a loop formed by the generator and the generator.

[0071] Because the grid-side converter forms a loop using the grid-side filter capacitor connected to its own AC side, and the generator-side converter forms a loop using the generator connected to its own AC side, and also utilizes the soft-start circuit in the wind power converter to charge the DC bus capacitor in the wind power converter, this closed-loop testing method eliminates the need for on-site personnel to perform preparatory work before fault detection of the two converters. For example, it eliminates the need for external DC power supply and manual short-circuiting operations, thus reducing the high-voltage contact risk faced by on-site personnel when performing fault detection on the two converters in the wind power converter. In addition, since manual short-circuiting is not required, it also avoids phase-to-phase short circuits that may occur during startup of the wind power converter after grid connection due to the short-circuit wire not being removed.

[0072] Another embodiment of this application provides a specific implementation method for fault detection of a converter using a circuit formed by the converter, the specific process of which is as follows: Figure 2 As shown, the specific steps include:

[0073] S210. Control the converter to perform inversion so that the output electrical parameters of each phase on its AC side are equal to the set electrical parameters.

[0074] The converter can be a three-phase converter, that is, it includes a three-phase power module, and correspondingly, the AC side of the converter includes three-phase output electrical parameters; the converter can also be a single-phase converter, that is, it includes a single-phase power module, and correspondingly, the AC side of the converter includes a single-phase output electrical parameter; no specific limitation is made here, and it can be determined according to the specific situation, and both are within the protection scope of this application; it should be noted that, under normal circumstances, a single-phase power module in the converter can also be referred to as a single-phase bridge arm in the converter.

[0075] The output electrical parameters can be either output current or output voltage. No specific limitation is made here. It can be determined according to the specific situation, and both are within the protection scope of this application.

[0076] The electrical parameters are preset based on the actual circuit structure and the bus voltage of the DC bus capacitor. Specifically, the set electrical parameters are less than or equal to the maximum output electrical parameters of the AC side of the converter.

[0077] Taking the output current as an example, the maximum output electrical parameter of the converter on the AC side is determined as follows: its effective value is equal to the product of the preset coefficient and the bus voltage of the DC bus capacitor, and the ratio of the equivalent total impedance of the circuit formed by the converter.

[0078] It should be noted that, under normal circumstances, since the circuit formed by the converter mainly includes inductive and capacitive loads, the output current on the AC side of the converter is reactive current. In addition, the preset coefficient is set in advance according to the waveform of each converter, and is not specifically limited here, but can be determined according to the specific situation.

[0079] In practical applications, in step S210, the output electrical parameters of each phase on the AC side of the converter can be gradually increased to the set electrical parameters, or the output electrical parameters of each phase on the AC side of the converter can be directly increased to the set electrical parameters; no specific limitation is made here, and it can be determined according to the specific situation. Both are within the protection scope of this application, but the former is the preferred implementation.

[0080] S220. Check whether the output electrical parameters of all phases on the AC side of the converter are consistent with the set electrical parameters.

[0081] If the output electrical parameters of at least one phase on the AC side of the converter are inconsistent with the set electrical parameters, then step S230 is executed; if the output electrical parameters of all phases on the AC side of the converter are consistent with the set electrical parameters, then step S240 is executed.

[0082] In a specific example, step S220 can be achieved by detecting whether all phase output electrical parameters on the AC side of the converter meet the set waveform requirements. The set waveform requirements are preset based on the waveform of the output electrical parameters on the AC side of the converter during normal operation. Therefore, when the output electrical parameters of one phase on the AC side of the converter meet the set requirements, it indicates that the corresponding phase power module in the converter can operate normally. Conversely, the corresponding phase power module cannot operate normally, i.e., a fault has occurred.

[0083] S230: Report a fault in the converter and identify the faulty power module within the converter.

[0084] S240 reports that the converter has no fault.

[0085] This embodiment also provides another specific implementation method for fault detection of a converter using a circuit formed by the converter, the specific process of which is as follows: Figure 3 ( Figure 3 (Taking only step S310 before step S210 as an example) As shown, in the above embodiment, before or simultaneously with step S210, the following steps are also included:

[0086] S310 controls the blocking of another converter.

[0087] In practical applications, converter blocking is equivalent to the converter not receiving the drive signal, that is, the converter stops operating.

[0088] The above are just two specific implementation methods for fault detection of a converter using a circuit formed by a converter. No specific limitation is made here, and the method can be determined according to the specific situation. All of them are within the protection scope of this application.

[0089] Another embodiment of this application provides a specific implementation of step S120, the specific process of which can be found in [reference needed]. Figure 4 ( Figure 4 Only Figure 2 Based on the above, the presentation includes the following steps:

[0090] S410. Perform fault detection on the grid-side converter.

[0091] It should be noted that fault detection of the converter has been described in detail in the above embodiments, and will not be repeated here.

[0092] S420. Determine if there is a fault in the grid-side converter.

[0093] If the grid-side converter is not faulty, proceed to steps S430 and S440; if the grid-side converter is faulty, proceed to step S460.

[0094] S430, Perform fault detection on the machine-side converter.

[0095] It should be noted that fault detection of the converter has been described in detail in the above embodiments, and will not be repeated here.

[0096] S440. Determine if there is a fault in the machine-side converter.

[0097] If the machine-side converter is not faulty, proceed to step S450; if the machine-side converter is faulty, proceed to step S460.

[0098] S450 controls the grid-connected operation of the wind power converter.

[0099] S460 controls the corresponding converter to stop inversion and controls the slow-start circuit to stop charging.

[0100] Typically, wind power converters are equipped with a discharge circuit for the DC bus capacitor. Therefore, after the slow-start circuit stops charging, the DC bus capacitor discharges until the voltage across its terminals is equal to zero. It should be noted that setting up a discharge circuit is a common technical means in the existing technology, and will not be described in detail here.

[0101] In this implementation, since fault detection of the generator-side converter is only performed after the grid-side converter has been found to be fault-free, the absence of faults in the generator-side converter indicates that the entire wind power converter is fault-free. Therefore, the wind power converter can be controlled to operate in grid-connected mode after this point.

[0102] The above is only one specific implementation of step S120. In practical applications, it includes, but is not limited to, the following: for example, the grid-side converter will only be fault-detected after the machine-side converter has no fault. This is not specifically limited and can be determined according to the specific situation. All of these are within the protection scope of this application.

[0103] Another embodiment of this application provides another specific implementation of the closed-loop testing method for wind power converters. The specific process of this implementation is as follows: Figure 5 As shown, this embodiment is applicable to the case where a filter capacitor switch is provided between the AC side of the grid-side converter and the grid-side filter capacitor; if step S120 adopts the above embodiment, then this embodiment of the grid-side closed-loop test method further includes the following steps before step S410:

[0104] S510 controls the closing of the filter capacitor switch.

[0105] This embodiment of the machine-side closed-loop test method further includes, before step S430:

[0106] S520, control filter capacitor switch is off.

[0107] This application provides a wind power converter, the specific structure of which is as follows: Figure 6 As shown, it specifically includes: stator switch Sd, frame switch Sk, DC bus capacitor Cd, grid-side converter 10, machine-side converter 20, grid-side filter capacitor 30, soft-start circuit 40, and controller ( Figure 6 (The view shown in the image is simplified and the controller is not shown); the specific connection relationships between the devices are as follows:

[0108] The AC side of the generator-side converter 20 is connected to the rotor of the generator G, and the DC side of the generator-side converter 20 is connected to the DC side of the grid-side converter 10 through the DC bus. The DC bus capacitor Cd is connected between the positive DC bus and the negative DC bus.

[0109] The AC side of the grid-side converter 10 is connected to the grid-side filter capacitor 30, and the connection point is connected to the power grid through the frame switch Sk; the AC side of the grid-side converter 10 is also connected to the first terminal of the stator switch Sd, and the second terminal of the stator switch Sd is connected to the stator of the generator G.

[0110] The AC side of the slow-start circuit 40 draws power from the grid, and the DC side of the slow-start circuit 40 is connected to the DC bus. The stator switch Sd, the frame switch Sk, the two converters, and the slow-start circuit 40 are all controlled by the controller, which is used to execute the closed-loop test method for the wind power converter provided in the above embodiment.

[0111] It should be noted that before performing the closed-loop test method for the wind power converter provided in the above embodiments, the wind power converter must be stopped, that is, both the stator switch Sd and the frame switch Sk are in the open state.

[0112] Assuming the capacitance of the grid-side filter capacitor 30 is Cw, then in this wind power converter, the equivalent total impedance of the circuit formed by the grid-side converter 10 and the grid-side filter capacitor 30 is Xw = 1 / jωCw; assuming the inductance of the rotor of the generator G is Lr, then in this wind power converter, the equivalent total impedance of the circuit formed by the generator-side converter 20 and the rotor of the generator G is Xj = jωLr.

[0113] The preferred implementation of the stator switch Sd or the frame switch Sk is a contactor; however, in practical applications, it may include, but is not limited to, the specific implementation of the contactor, and may be determined according to the specific circumstances, all of which are within the scope of protection of this application.

[0114] Optionally, the converter can be a three-phase converter, i.e., it includes a three-phase power module 01, such as... Figure 6 As shown; it can also be a single-phase converter, that is, it includes a one-phase power module 01; no specific limitation is made here, it can be determined according to the specific situation, and all are within the protection scope of this application; in addition, the one-phase power module 01 in the converter can also be referred to as a one-phase bridge arm in the converter.

[0115] Optionally, the power module 01 can be a three-level topology or a two-level topology; no specific limitation is made here, and it can be determined according to the specific situation, both of which are within the protection scope of this application. It should be noted that both three-level and two-level topologies are relatively mature topologies in the prior art, and will not be described in detail here. The specific structure of the two-level topology is as follows: Figure 6 As shown.

[0116] Optionally, the power module constituting the power module 01 can be an IGBT, an IEGT, or an IGCT. In practical applications, it may include, but is not limited to, any of these. No specific limitation is made here. It may be determined according to the specific circumstances, and all of them are within the protection scope of this application.

[0117] In one specific example, the grid-side converter 10 is a three-phase converter, such as... Figure 6 As shown, the grid-side filter capacitor 30 specifically includes three capacitors, one end of which is connected in series, and the other end of which is connected to the three output ports of the AC side of the grid-side converter, respectively.

[0118] The above is only one implementation of the grid-side converter 10. In practical applications, the above implementation is not limited to, but can be determined according to the specific circumstances. All of these are within the protection scope of this application.

[0119] like Figure 6 As shown, the wind power converter also includes: at least two electrical parameter sensors ( Figure 6 (The example shown uses current sensors CT1 to CT6); where:

[0120] Each phase of the AC side of the machine-side converter 20 is equipped with an electrical parameter sensor. Figure 6 (Only current sensors CT1 to CT3 are shown as examples); each phase of the AC side of the grid-side converter 10 is equipped with an electrical parameter sensor. Figure 6 (The example shown uses current sensors CT4 to CT6.)

[0121] Each electrical parameter sensor is used to collect the output electrical parameters of each phase on the AC side of the grid-side converter 10 and the output electrical parameters of each phase on the AC side of the machine-side converter 20; each electrical parameter sensor is communicatively connected to the controller.

[0122] If the electrical parameter is current, then the electrical parameter sensor is a current sensor; if the electrical parameter is voltage, then the electrical parameter sensor is a voltage sensor.

[0123] This embodiment provides a specific implementation of the soft-start circuit 40, the specific structure of which is as follows: Figure 7 As shown, it specifically includes: a boost rectifier unit 41 and a soft-start switch Sr; wherein, the boost rectifier unit 41 and the soft-start switch Sr are connected in series, and both the boost rectifier unit 41 and the soft-start switch Sr are controlled by a controller.

[0124] In practical applications, the boost rectifier unit 41 can be composed of a single device or multiple devices, such as a boost unit and a rectifier unit. No specific limitation is made here, and it can be determined according to the specific situation. All of these are within the protection scope of this application.

[0125] The preferred embodiment of the boost rectifier unit is a Boost boost rectifier unit; however, in practical applications, it may include, but is not limited to, this application. It may be determined according to the specific circumstances and is within the scope of protection of this application.

[0126] It should be noted that when the boost rectifier unit is a Boost boost rectifier unit, if the converter is a traditional three-level wind power converter, this soft-start circuit can save the boost transformer and rectifier bridge units compared to existing technologies. In existing traditional soft-start circuits, a boost transformer is usually used to boost the AC power first, and then two rectifier bridge units are used to rectify the positive and negative half-buses respectively. However, when using the Boost boost rectifier unit, the AC power can be boosted and rectified directly. Furthermore, the Boost boost rectifier unit only requires two-phase input, eliminating the need for three-phase input. Therefore, it not only saves the number of rectifier bridge units but also the number of input cables required.

[0127] Optionally, the boost rectifier unit 41 can be composed of IGBTs, IEGTs, or IGCTs. In practical applications, it may include, but is not limited to, these options. No specific limitation is made here. It may be determined according to the specific circumstances, and all of them are within the protection scope of this application.

[0128] The preferred embodiment of the soft-start switch Sr is a contactor. In practical applications, it includes, but is not limited to, contactors. It can be determined according to the specific circumstances and is within the scope of protection of this application.

[0129] The above is only a preferred embodiment of the slow-start circuit 40. In practical applications, it includes, but is not limited to, replacing the boost rectifier unit 41 with a buck rectifier unit. No specific limitation is made here, and it can be determined according to the specific situation. All of these are within the protection scope of this application.

[0130] This embodiment also provides another implementation of the wind power converter, the specific structure of which can be found in [reference needed]. Figure 8 ( Figure 8 Only Figure 7 Based on the above implementation method, the method further includes: a filter capacitor switch Sv; the filter capacitor switch Sv is disposed between the grid-side filter capacitor 30 and the AC side of the grid-side converter 10; the filter capacitor switch Sv is controlled by a controller.

[0131] This embodiment also provides another implementation of the wind power converter, the specific structure of which can be found in [reference needed]. Figure 9 ( Figure 9 Only Figure 8 Based on the above implementation method, the following components are also included: grid-side filter inductor Lw, machine-side filter inductor Lj, machine-side filter capacitor 50, and stator filter capacitor 60; the connection relationships of each component are as follows:

[0132] The grid-side filter inductor Lw is located between the AC side of the grid-side converter 10 and the first terminal of the stator switch Sd.

[0133] The machine-side filter inductor Lj is located between the AC side of the machine-side converter 20 and the rotor in the generator G.

[0134] The machine-side filter capacitor 50 is connected to the AC side of the machine-side converter 20.

[0135] The stator filter capacitor 60 is connected to the stator in the generator G.

[0136] In one example, such as Figure 9 As shown, the specific structure of the stator filter capacitor 60 is the same as that of the grid-side filter capacitor 30, and will not be described in detail here; the machine-side filter capacitor 50 is similar to the grid-side filter capacitor 30, except that each phase branch in the machine-side filter capacitor 50 is a series branch formed by a resistor and a capacitor.

[0137] by Figure 9 For example, assuming the capacitance of the grid-side filter capacitor 30 is Cw and the inductance of the grid-side filter inductor Lw is Lw, then in this wind power converter, the equivalent total impedance of the circuit formed by the grid-side converter 10 and the grid-side filter capacitor 30 is Xw = 1 / jωCw + jωLw; assuming the inductance of the rotor of the generator G is Lr and the inductance of the machine-side filter inductor Lj is Lj, then in this wind power converter, the equivalent total impedance of the circuit formed by the machine-side converter 20 and the rotor of the generator G is Xj = jωLr.

[0138] It should be noted that in practical applications, the inductance of the machine-side filter inductor Lj is much smaller than the rotor inductance of the generator G, so it can be ignored when calculating the equivalent total impedance.

[0139] The features described above in the disclosed embodiments can be substituted or combined with each other, enabling those skilled in the art to implement or use this application. The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A closed-loop testing method for a wind power converter, characterized in that, include: The soft-start circuit in the wind power converter is controlled to draw power from the grid side of the wind power converter to charge the DC bus capacitor in the wind power converter. After the bus voltage of the DC bus capacitor stabilizes, the corresponding converters are tested for faults in stages using the circuits formed by the grid-side converter and the grid-side filter capacitor in the wind power converter, and the circuits formed by the generator-side converter and the generator in the wind power converter.

2. The closed-loop testing method for wind power converters according to claim 1, characterized in that, Using a circuit formed by a converter, fault detection of the converter is performed, including: Control the converter to perform inversion so that the output electrical parameters of each phase on its AC side are equal to the set electrical parameters; When it is detected that the output electrical parameters of at least one phase on the AC side of the converter are inconsistent with the set electrical parameters, the converter is reported to have a fault, and the power module in the converter that is faulty is also reported.

3. The closed-loop testing method for wind power converters according to claim 2, characterized in that, Controlling the converter to perform inversion, so that the output electrical parameters of each phase on its AC side are equal to the set electrical parameters, includes: The converter is controlled to perform inversion, so that the output electrical parameters of each phase on its AC side are gradually increased to the set electrical parameters.

4. The closed-loop testing method for wind power converters according to claim 2, characterized in that, Output electrical parameters include: output current, or output voltage.

5. The closed-loop testing method for wind power converters according to claim 2, characterized in that, The set electrical parameters are less than or equal to the maximum output electrical parameters on the AC side of the converter.

6. The closed-loop testing method for wind power converters according to claim 5, characterized in that, If the output electrical parameter is the output current, then the effective value of the maximum output electrical parameter on the AC side of the converter is equal to the product of the preset coefficient and the bus voltage of the DC bus capacitor, and the ratio of the equivalent total impedance of the circuit formed by the converter.

7. The closed-loop testing method for wind power converters according to claim 2, characterized in that, In addition to controlling the converter to perform inversion, it also includes: Control another converter to block the wave.

8. The closed-loop test method for a wind power converter according to any one of claims 1 to 7, characterized in that, Fault detection was performed on the two converters in stages, including: Fault detection is performed on the grid-side converter; When there is no fault in the grid-side converter, fault detection is performed on the machine-side converter; When there is no fault in the generator-side converter, the wind power converter is controlled to operate in grid-connected mode.

9. The closed-loop test method for wind power converters according to claim 8, characterized in that, When a fault occurs in the grid-side converter or the machine-side converter, the following method is also included: Control the corresponding converter to stop inverting, and control the soft-start circuit to stop charging.

10. The closed-loop testing method for a wind power converter according to claim 8, characterized in that, If a filter capacitor switch is provided between the AC side of the grid-side converter and the grid-side filter capacitor, then before fault detection of the grid-side converter, the following steps are also included: Control the closing of the filter capacitor switch; Before performing fault detection on the machine-side converter, the following is also included: The filter capacitor switch is turned off.

11. A wind power converter, characterized in that, include: Stator switch, frame switch, DC bus capacitor, grid-side converter, machine-side converter, grid-side filter capacitor, soft-start circuit and controller; among which: The AC side of the machine-side converter is connected to the rotor of the generator; The DC side of the machine-side converter is connected to the DC side of the grid-side converter via a DC bus, and the DC bus capacitor is connected between the positive DC bus and the negative DC bus. The AC side of the grid-side converter is connected to the grid-side filter capacitor, and the connection point is connected to the power grid through the frame switch. The AC side of the grid-side converter is also connected to the first terminal of the stator switch, and the second terminal of the stator switch is connected to the stator of the generator; The AC side of the slow-start circuit draws power from the power grid, and the DC side of the slow-start circuit is connected to the DC bus. The stator switch, frame switch, two converters, and soft-start circuit are all controlled by the controller, which is used to execute the closed-loop test method for the wind power converter as described in any one of claims 1 to 10.

12. The wind power converter according to claim 11, characterized in that, The soft-start circuit includes: a boost rectifier unit and a soft-start switch connected in series; Both the boost rectifier unit and the soft-start switch are controlled by the controller.

13. The wind power converter according to claim 12, characterized in that, The boost rectifier unit is a Boost boost rectifier unit.

14. The wind power converter according to claim 11, characterized in that, It also includes: filter capacitor switches; wherein: The filter capacitor switch is located between the grid-side filter capacitor and the AC side of the grid-side converter; The filter capacitor switch is controlled by the controller.

15. The wind power converter according to claim 11, characterized in that, The power module in the converter is either a three-level topology or a two-level topology.

16. The wind power converter according to any one of claims 11 to 15, characterized in that, Also includes: At least two electrical parameter sensors; wherein: Each phase of the AC side of the machine-side converter and each phase of the AC side of the grid-side converter are equipped with an electrical parameter sensor. The electrical parameter sensor is used to collect the output electrical parameters of each phase of the AC side of the machine-side converter and the output electrical parameters of each phase of the AC side of the grid-side converter. The electrical parameter sensor is communicatively connected to the controller.

17. The wind power converter according to any one of claims 11 to 15, characterized in that, It also includes at least one of the following: grid-side filter inductor, machine-side filter inductor, machine-side filter capacitor, and stator filter capacitor; wherein: The grid-side filter inductor is disposed between the AC side of the grid-side converter and the first terminal of the stator switch; The machine-side filter inductor is disposed between the AC side of the machine-side converter and the rotor; The machine-side filter capacitor is connected to the AC side of the machine-side converter; The stator filter capacitor is connected to the stator.

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