A control method and system for a multi-wind-wheel medium-voltage wind turbine generator, and a computer device

Abstract

The present application belongs to the field of wind power technology, and discloses a control method of a multi-wind-wheel medium-voltage wind turbine, wherein the multi-wind-wheel medium-voltage wind turbine adopts a modular structure, each phase of a, b and c includes n modules, each module includes a wind wheel, a permanent magnet synchronous generator, a three-phase active rectifier, a DC bus capacitor and an H-bridge inverter, and n H-bridge inverters of each phase are cascaded; the method includes a three-phase active rectifier control step and a cascaded H-bridge inverter control step. The method of the present application embodiment realizes the suppression of DC bus voltage fluctuation by increasing a resonance regulator on the basis of a conventional PI regulator, and reduces the requirement for the capacitance value of the DC bus capacitor; the multi-wind-wheel medium-voltage wind turbine utilizes the above control method, realizes the suppression of DC bus voltage fluctuation under the premise of ensuring that the wind turbine captures wind energy to the maximum extent, reduces the requirement for the capacitance value of the DC bus capacitor, and thus further reduces the cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind power technology, and particularly relates to a multi-wind-wheel medium-voltage wind turbine control method and system and a computer device. BACKGROUND

[0002] From the perspective of the wind energy capture device of a wind power system, current commercial high-power wind power systems are basically horizontal-axis structures, which capture wind power by a group of wind wheels (mostly three-blade). With the increase of the single-machine capacity of the wind power system, the size of the wind wheel becomes larger and larger. Since the volume and weight of the wind wheel are directly proportional to the cube of the wind wheel radius, and the power captured by the wind wheel is directly proportional to the square of the wind wheel radius, with the increase of the size of the wind wheel, the increase speed of the weight and cost of the wind wheel is higher than that of the power captured by the wind wheel. Although the development of glass composite materials makes the manufactured blades longer and longer, however, when the single-machine capacity of the wind turbine reaches several megawatts or even 10 MW, the weight and cost of the conventional wind wheel system will become a problem that cannot be ignored, and poses a severe challenge to the cost of the entire system, transportation and installation of the wind wheel, tower load and the like.

[0003] From the perspective of the transmission chain of the wind power system, the current mainstream variable-speed wind power system is a double-fed type and a full-power conversion type system. In the double-fed type wind power system, the wind wheel drives a high-speed asynchronous generator after being speeded up by a multi-stage gearbox. As a typical representative of the full-power conversion type wind power system, the permanent magnet direct drive type wind turbine is directly driven by a multi-pole permanent magnet synchronous generator (PMSG) by the wind wheel. Compared with the double-fed type wind power system, the permanent magnet direct drive type wind turbine has the advantages of simple transmission chain structure, high efficiency, low maintenance cost and high reliability, and has been applied by more and more wind turbine manufacturers. However, with the increase of the single-machine capacity of the wind power system, the radial length of the multi-pole permanent magnet synchronous generator must be increased, and the increase of the size and weight of the multi-pole permanent magnet synchronous generator limits the application of the system; although a half-direct drive scheme of driving a medium-speed generator by a one-stage gear can be adopted, the use of the gearbox will reduce the reliability of the system and increase the maintenance cost.

[0004] From the grid-connected voltage level of wind power generation system, current wind power system basically adopts 690V grid connection, and then connects to medium voltage power grid through step-up transformer. Through calculation, when adopting 690V grid connection, the rated output current of 2MW wind power system is 1673A, and when the single machine capacity increases to 10MW, the rated output current will be as high as 8367A, therefore, the grid-connected converter needs to adopt parallel connection to cope with the increase of current. However, parallel connection of the converter may cause circulating current, although the circulating current can be inhibited through control, but the system control complexity is increased; and such a large current will cause high voltage drop and high loss on the transmission cable from the nacelle to the tower foundation. Although the step-up transformer can be placed in the nacelle and the medium voltage transmission can be adopted to reduce the transmission current, the huge volume of the step-up transformer will occupy the very limited space in the nacelle, and the increase of weight will also increase the load of the entire tower.

[0005] Therefore, from the above aspects of wind energy capture, conversion and grid connection, it is a very practical and urgent task to develop a high-reliability, light-weight, easy-to-transport and install high-power wind power system. The multi-wind-wheel medium-voltage wind turbine topology is shown in Figure 1 The machine adopts modular structure, each module is composed of a wind wheel, a permanent magnet synchronous generator PMSG, a three-phase active rectifier, a DC bus capacitor and an H-bridge inverter. The wind wheel directly drives the PMSG, the PMSG stator is connected to the three-phase active rectifier, the H-bridge inverters are cascaded and connected to the medium voltage grid through a filter inductor, and the DC bus of each H-bridge inverter is powered by the three-phase active rectifier.

[0006] The existing multi-wind-wheel medium-voltage wind turbine control strategy realizes maximum wind energy capture through the three-phase active rectifier, and realizes stable DC bus voltage through the cascaded H-bridge inverter, therefore, the existing multi-wind-wheel medium-voltage wind turbine control strategy has high requirements for the capacitance value of the DC bus capacitor, and cannot effectively suppress the fluctuation of the DC bus voltage through improvement of the control strategy, so as to realize the goal of reducing the capacitance value of the DC bus capacitor.

[0007] Therefore, how to provide a multi-wind-wheel medium-voltage wind turbine control method to suppress the fluctuation of the DC bus voltage is a problem to be solved at present. SUMMARY

[0008] This invention provides a control method for multi-rotor medium-voltage wind turbines to address the technical problem of DC bus voltage fluctuations. To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments. Its sole purpose is to present some concepts in a simple form as a prelude to the detailed description that follows.

[0009] According to a first aspect of the present invention, a control method for a multi-rotor medium-pressure wind turbine is provided.

[0010] In one embodiment, a control method for a multi-rotor medium-voltage wind turbine generator set is provided. The multi-rotor medium-voltage wind turbine generator set adopts a modular structure, with each phase (a, b, c) comprising n modules. Each module includes: a wind turbine, a permanent magnet synchronous generator, a three-phase active rectifier, a DC bus capacitor, and an H-bridge inverter. The n H-bridge inverters of each phase are cascaded. The method includes a three-phase active rectifier control step and a cascaded H-bridge inverter control step.

[0011] The three-phase active rectifier control steps include:

[0012] The target value of the q-axis voltage u is obtained by the PIR regulator. q and d-axis voltage target value u d ;

[0013] Based on the target value of the q-axis voltage u q and d-axis voltage target value u d The target value of the three-phase voltage of the three-phase active rectifier is obtained by the inverse Park transformation from dq to abc.

[0014] Based on the target value of the three-phase voltage of the three-phase active rectifier, the switching control signal of the three-phase active rectifier is obtained by sinusoidal pulse width modulation.

[0015] The control steps for the cascaded H-bridge inverter include:

[0016] Based on the target voltage values ​​u of the d-axis and q-axis of the cascaded H-bridge inverter d and u q Then, through the Park inverse transformation from dq to abc, the target value u of the three-phase voltage of the cascaded H-bridge inverter is obtained. a u b and u c ;

[0017] Within a certain phase x, the target output power P of each permanent magnet synchronous generator is... xj Divide by the average value P of the target output power of all n modules in that phase. xav Calculate the proportionality factor k for each factor. xj ; each proportionality factor kxj multiplied to obtain the output voltage target value u of each H-bridge inverter x xj ;

[0018] According to the output voltage target value u of each H-bridge inverter, the switch control signal of each H-bridge inverter is obtained through carrier phase shift modulation.

[0019] Optionally, the q-axis voltage target value u is obtained by the following steps: q

[0020] According to the DC bus voltage rated value u dc_ref and the DC bus voltage actual value u dc , the q-axis current target value i * q ;

[0021] According to the q-axis current target value i * q and the q-axis current actual value i q , the q-axis voltage target value u q is obtained through a PIR regulator.

[0022] Optionally, the step of obtaining the q-axis current target value i dc_ref dc according to the DC bus voltage rated value u * q includes:

[0023] The DC bus voltage rated value u dc_ref is subtracted from the DC bus voltage actual value u dc , and the q-axis current target value i * q is obtained through a PIR regulator.

[0024] Optionally, the step of obtaining the q-axis voltage target value u * q according to the q-axis current target value i q q includes:

[0025] The q-axis current target value i * q is subtracted from the q-axis current actual value i q , and the q-axis voltage target value u q is obtained through a PIR regulator.

[0026] Optionally, the d-axis voltage target value u is obtained by the following steps: d ​​​​​

[0027] Based on the actual value of the d-axis current i d and the set target value i of the d-axis current * d Then, through the PIR regulator, the target value u of the d-axis voltage is obtained. d .

[0028] Optionally, the step of basing the actual value of the d-axis current i d and the set target value i of the d-axis current * d Then, through the PIR regulator, the target value u of the d-axis voltage is obtained. d The steps include:

[0029] Set the target value i for the d-axis current * d Compared with the actual value of d-axis current i d The difference is calculated, and then the result is processed by a PIR regulator to obtain the target d-axis voltage value u. d .

[0030] Optionally, the transfer function of the PIR regulator is shown in the following equation:

[0031]

[0032] In the formula, k p k is the proportional adjustment coefficient. i k is the integral adjustment coefficient. r ω is the resonance adjustment coefficient. c ω is the cutoff frequency, and ω0 is the resonant frequency.

[0033] Optionally, the target values ​​u of the d-axis and q-axis voltages of the cascaded H-bridge inverter are... d and u q Obtained through the following steps:

[0034] The target output power P of the permanent magnet synchronous generator is obtained based on the rotational speed of each wind turbine to achieve maximum power point tracking control. xj ,x=a,b,c,j=1,2,…,n;

[0035] Sum the power target values ​​of all 3n modules. Then divide by the d-axis component u of the grid voltage. gd The target value i of the d-axis component of the grid-connected current is obtained. * d The target value i of the q-axis component of the grid-connected current is determined based on the reactive power output requirements of the wind turbine generator. * q ;

[0036] The target value i of the d-axis component of the grid-connected current. * dAnd q-axis component target value i * q Subtracting the d-axis current actual value and the q-axis current actual value of the grid-connected current respectively, and then passing through the PI regulator respectively, the d-axis and q-axis voltage target values u of the cascade H-bridge inverter are obtained d And u q .

[0037] According to a second aspect of the embodiments of the present application, a computer device is provided.

[0038] In some embodiments, the computer device comprises a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0039] According to a third aspect of the embodiments of the present application, a multi-wind-wheel medium-voltage wind turbine generator control system is provided.

[0040] In some embodiments, the multi-wind-wheel medium-voltage wind turbine generator control system comprises a computer device, which comprises a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0041] The technical solutions provided by the embodiments of the present application can include the following beneficial effects:

[0042] The multi-wind-wheel medium-voltage wind turbine generator utilizes the above control method to realize the stability of each DC bus voltage through the three-phase active rectifier control step, realizes the maximum wind energy capture and the decoupling output of active power and reactive power of the entire system through the cascade H-bridge inverter control step, and realizes the suppression of DC bus voltage fluctuation and reduces the requirement for DC bus capacitor capacity value on the premise of maximizing the capture of wind energy, thereby further reducing the cost.

[0043] In the three-phase active rectifier control step, the suppression of DC bus voltage fluctuation and the reduction of the requirement for DC bus capacitor capacity value are realized by adding a resonant regulator on the basis of a conventional PI regulator.

[0044] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings, which are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0046] Figure 1 is a system block diagram of a multi-wind-wheel medium-voltage wind turbine according to an exemplary embodiment;

[0047] Figure 2 is a control block diagram of a three-phase active rectifier according to an example embodiment;

[0048] Figure 3 is a control block diagram of a cascaded H-bridge inverter according to an example embodiment;

[0049] Figure 4 is a structural schematic diagram of a computer device according to an example embodiment. DETAILED DESCRIPTION

[0050] The following description and drawings are illustrative of the specific embodiments herein and are not intended to limit the scope of the embodiments. Portions and features of some embodiments can be included in, or alternative to, portions and features of other embodiments. The range of variations of the embodiments herein that encompass the whole range of equivalents of the claims are not intended to be limited to the specific variations that have been described. In the description of embodiments, terms of degree such as "substantially", "approximately", "generally", "essentially", "like" and "about" are used to describe and account for subjective variations in measurements, sizes, shapes and other dimensions that can occur in the manufacture of articles, as well as to describe and account for subjective variations in the properties of materials that can occur from batch to batch. Such terms are also used, not only to account for variations and / or differences in the manufacturing process, but also to describe and account for variations and / or differences in measurements, sizes, shapes, and other dimensions that will occur because of differences in the environments, during which a measurement, size, shape, or other dimension is taken. Unless otherwise defined, all terms of degree such as "substantially", "approximately", "generally", "essentially", "like" and "about" should be construed as permitting some variations from the recited starting point or ending point due to expected variations inherent in the manufacturing or measurement process. In the description of embodiments, the terms "first", "second", and the like do not necessarily denote any ordinal, chronological or spatial relationship, nor do they imply or require any particular structure, sequence, or ordering according to the described terms. Rather, the terms "first", "second", and the like are used to distinguish one element from another, and are not used to denote any actual or relative position, or ordering of the elements. In fact, a first element can also be termed a second element, and, conversely, a second element can also be termed a first element. Furthermore, the terms "comprise", "comprises", "comprising", "include", "includes", "including" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a structure, device or apparatus that comprises a list of elements is not necessarily limited to those elements, but can include other elements not expressly listed or inherent to such structure, device or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the structure, device or apparatus. The various embodiments are described in a progressive manner, each focusing on the differences from other embodiments, and the same or similar parts between embodiments can be referred to each other.

[0051] The terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, as used herein, refer to the orientation or positional relationship based on the orientation or position shown in the drawings, and are only used to facilitate the description of the present document and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In the description of the embodiments herein, unless otherwise specified and limited, the terms "mount", "connect", "connection" should be understood broadly, for example, it can be a mechanical connection or an electrical connection, it can be a communication between two elements inside, it can be a direct connection, or an indirect connection through an intermediate medium, and the specific meaning of the above terms can be understood by the person skilled in the art according to the specific circumstances.

[0052] In this document, the term "a plurality of" means two or more, unless otherwise specified.

[0053] In this document, the character " / " represents a kind of "or" relationship between the front and rear objects. For example, A / B represents: A or B.

[0054] In this document, the term "and / or" is a description of the relationship between the objects, which means that there can be three kinds of relationships. For example, A and / or B, which means: A or B, or, A and B, three kinds of relationship.

[0055] In the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0056] Figure 1 An embodiment of a multi-wind-wheel medium-voltage wind turbine is shown.

[0057] In this embodiment, the multi-wind-wheel medium-voltage wind turbine adopts a modular structure, each phase a, b, c includes n modules, each module includes: a wind wheel, a permanent magnet synchronous generator PMSG, a three-phase active rectifier 10, a DC bus capacitor 30 and an H-bridge inverter 20, and n H-bridge inverters of each phase are cascaded.

[0058] The embodiment of the present application provides a multi-wind-wheel medium-voltage wind turbine control method, which comprises a three-phase active rectifier control step and a cascaded H-bridge inverter control step. The three-phase active rectifier control step realizes the stability of each DC bus voltage, and the cascaded H-bridge inverter control step realizes the maximum wind energy capture of the whole system and the decoupling output of active power and reactive power.

[0059] As shown in Figure 2 , the three-phase active rectifier control step comprises: obtaining q-axis voltage target value u q and d-axis voltage target value u d through PIR regulator; obtaining three-phase active rectifier three-phase voltage target value through dq to abc Park inverse transformation according to q-axis voltage target value u q and d-axis voltage target value u d ; obtaining the switching tube control signal of the three-phase active rectifier through sinusoidal pulse width modulation SPWM according to the three-phase active rectifier three-phase voltage target value.

[0060] Optionally, q-axis voltage target value u q is obtained by the following steps: obtaining q-axis current target value i * q according to DC bus voltage rated value u dc_ref and DC bus voltage actual value u dc ; obtaining three-phase active rectifier three-phase voltage target value through dq to abc Park inverse transformation according to q-axis current target value i * q and q-axis current actual value iq , and the q-axis voltage target value u q is obtained through a PIR regulator. dc_ref Specifically, the DC bus voltage rated value u dc is subtracted from the DC bus voltage actual value u * , and the q-axis current target value i q is obtained through a PIR (proportional, integral, resonant) regulator. * q is subtracted from the q-axis current actual value i q , and the q-axis voltage target value u q is obtained through a PIR regulator.

[0061] Alternatively, the d-axis voltage target value u d is obtained according to the d-axis current actual value i d and the set d-axis current target value i * d , and the d-axis voltage target value u d is obtained through a PIR regulator. * d Specifically, the set d-axis current target value i d is subtracted from the d-axis current actual value i d , and the d-axis voltage target value u * d is obtained through a PIR regulator. Alternatively, the d-axis current target value i p i is usually set to 0.

[0062] The method of the embodiment of the application, on the basis of a conventional PI regulator, realizes suppression of DC bus voltage fluctuation by adding a resonant regulator (R regulator), and reduces the requirement for the capacitance value of the DC bus capacitor. The transfer function of the PIR regulator is shown in formula (1), and the three parts are proportional, integral, and resonant regulators.

[0063]

[0064] In the formula, k p is a proportional regulation coefficient, k i is an integral regulation coefficient, k r is a resonant regulation coefficient, ω c is a cutoff frequency, and ω0 is a resonant frequency.

[0065] As shown in FIG. 1, each phase is connected with n H-bridge inverters in cascade, and there are 3n H-bridge inverters in total. The control steps of the cascade H-bridge inverters include: obtaining the d-axis and q-axis voltage target values u d and u q of the cascade H-bridge inverters, and then obtaining the three-phase voltage target value u a of the cascade H-bridge inverters through Park inverse transformation from dq to abc.a u b and u c Within a certain phase x, the target output power P of each permanent magnet synchronous generator. xj Divide by the average value P of the target output power of all n modules in that phase. xav Calculate the proportionality factor k for each factor. xj x = a, b, c, j = 1, 2, ..., n; each proportionality factor k xj Then compare it with the target value u of the phase voltage. x Multiply to obtain the target output voltage u of each H-bridge inverter xj Based on the target output voltage value of each H-bridge inverter, the switching control signal of each H-bridge inverter is obtained through carrier phase-shift modulation (PS-SPWM).

[0066] The average value P of the target output power of all n modules in a certain phase xav As shown in the announcement (2):

[0067]

[0068] Optionally, the target values ​​u of the d-axis and q-axis voltages of the cascaded H-bridge inverter. d and u q The target output power P of the permanent magnet synchronous generator for achieving maximum power point tracking control is obtained through the following steps: Based on the rotational speeds of each wind turbine, the target output power P of the permanent magnet synchronous generator is calculated. xj Let x = a, b, c, j = 1, 2, ..., n; sum the power target values ​​of all 3n modules. Then divide by the d-axis component u of the grid voltage. gd The target value i of the d-axis component of the grid-connected current is obtained. * d The target value i of the q-axis component of the grid-connected current is determined based on the reactive power output requirements of the wind turbine generator. * q The target value i of the d-axis component of the grid-connected current. * d and the target value i of the q-axis component * q The difference between the actual d-axis current value and the actual q-axis current value of the grid-connected current is calculated, and then passed through a PI regulator to obtain the target d-axis and q-axis voltage values ​​u of the cascaded H-bridge inverter. d and u q .

[0069] Optionally, the step of determining the target output power value of the permanent magnet synchronous generator (PMSG) for achieving maximum power point tracking (MPPT) based on the rotational speeds of each wind turbine includes: determining the target output power value P of the PMSG based on the optimal mechanical characteristic curve obtained from the rotational speeds of each wind turbine. xj, x = a, b, c, represents a, b, c three-phase, j = 1, 2, …, n, for example, P a1 represents the target value of the PMSG output power in the a-phase first module.

[0070] Optionally, the q-axis component target value of the grid-connected current i * q In the step of determining the q-axis component target value of the grid-connected current i

[0071] In one embodiment, a computer device, which can be a server, is provided, and an internal structure diagram of the computer device can be as shown in FIG. 1. Figure 4 The computer device includes a processor, a memory and a network interface connected through a system bus. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The database of the computer device is configured to store static information and dynamic information data. The network interface of the computer device is configured to communicate with an external terminal through a network connection. The computer program is executed by the processor to implement the steps in the above method embodiments.

[0072] Those skilled in the art can understand that Figure 4 The structure shown in FIG. 1 is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. Specifically, the computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0073] In one embodiment, a computer device is also provided, which includes a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.

[0074] In one embodiment, a computer readable storage medium is provided, which stores a computer program. The computer program is executed by a processor to implement the steps in the above method embodiments.

[0075] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiments. Any reference to memory, storage, database or other medium used in each embodiment of the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0076] The present application is not limited to the structures described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present application is only limited by the appended claims.

Claims

1. A control method for a multi-rotor medium-pressure wind turbine generator set, characterized in that, The multi-rotor medium-voltage wind turbine adopts a modular structure, with each phase (a, b, c) comprising n modules. Each module includes: a wind turbine, a permanent magnet synchronous generator, a three-phase active rectifier, a DC bus capacitor, and an H-bridge inverter. The n H-bridge inverters of each phase are cascaded. The method includes a three-phase active rectifier control step and a cascaded H-bridge inverter control step. The three-phase active rectifier control steps include: The target value of the q-axis voltage u is obtained by the PIR regulator. q and d-axis voltage target value u d Wherein, the target value of the q-axis voltage u q Obtained through the following steps: based on the rated DC bus voltage u dc_ref The actual value of DC bus voltage u dc The target value of the q-axis current i is obtained. * q Based on the target value i of the q-axis current * q Compared with the actual value of the q-axis current i q Then, through the PIR regulator, the target value u of the q-axis voltage is obtained. q The target value of the d-axis voltage u d The following steps are used to obtain: based on the actual value of the d-axis current i d and the set target value i of the d-axis current * d Then, through the PIR regulator, the target value u of the d-axis voltage is obtained. d ; Based on the target value of the q-axis voltage u q and d-axis voltage target value u d The target value of the three-phase voltage of the three-phase active rectifier is obtained by the inverse Park transformation from dq to abc. Based on the target value of the three-phase voltage of the three-phase active rectifier, the switching control signal of the three-phase active rectifier is obtained by sinusoidal pulse width modulation. The control steps for the cascaded H-bridge inverter include: Based on the target voltage values ​​u of the d-axis and q-axis of the cascaded H-bridge inverter d and u q Then, through the Park inverse transformation from dq to abc, the target value u of the three-phase voltage of the cascaded H-bridge inverter is obtained. a u b and u c The target voltage values ​​u of the d-axis and q-axis of the cascaded H-bridge inverter. d and u q The target output power P of the permanent magnet synchronous generator for achieving maximum power point tracking control is obtained through the following steps: Based on the rotational speeds of each wind turbine, the target output power P of the permanent magnet synchronous generator is calculated. xj Where x = a, b, c, j = 1, 2, ..., n; sum the power target values ​​of all 3n modules. Then divide by the d-axis component u of the grid voltage. gd The target value of the d-axis current i of the grid-connected current is obtained. * d The target value of the q-axis current i is determined based on the reactive power output requirements of the wind turbine generator. * q The target value of the d-axis current i of the grid-connected current. * d and the target value of the q-axis current i * q The difference between the actual d-axis current value and the actual q-axis current value of the grid-connected current is calculated, and then passed through a PI regulator to obtain the target d-axis and q-axis voltage values ​​u of the cascaded H-bridge inverter. d and u q ; Within a certain phase x, the target output power P of each permanent magnet synchronous generator is... xj Divide by the average value P of the target output power of all n modules in that phase. xav Calculate the proportionality factor k for each factor. xj ; each proportionality factor k xj Then compare it with the target value u of the phase voltage. x Multiply to obtain the target output voltage u of each H-bridge inverter xj ; Based on the target output voltage value of each H-bridge inverter, the switching control signal of each H-bridge inverter is obtained through carrier phase-shift modulation.

2. The control method for a multi-rotor medium-pressure wind turbine as described in claim 1, characterized in that, The DC bus voltage rating u dc_ref The actual value of DC bus voltage u dc The target value of the q-axis current i is obtained. * q The steps include: DC bus voltage rating u dc_ref The actual value of DC bus voltage u dc The difference is calculated, and then the target value of the q-axis current i is obtained through a PIR regulator. * q .

3. The control method for a multi-rotor medium-pressure wind turbine as described in claim 1, characterized in that, The target value i based on the q-axis current * q Compared with the actual value of the q-axis current i q Then, through the PIR regulator, the target value u of the q-axis voltage is obtained. q The steps include: Set the target value of the q-axis current i * q Compared with the actual value of the q-axis current i q The difference is calculated, and then the result is processed by a PIR regulator to obtain the target q-axis voltage value u. q .

4. The control method for a multi-rotor medium-pressure wind turbine as described in claim 1, characterized in that, The actual value of the d-axis current i d and the set target value i of the d-axis current * d Then, through the PIR regulator, the target value u of the d-axis voltage is obtained. d The steps include: Set the target value i for the d-axis current * d Compared with the actual value of d-axis current i d The difference is calculated, and then the result is processed by a PIR regulator to obtain the target d-axis voltage value u. d .

5. A control method for a multi-rotor medium-pressure wind turbine as described in any one of claims 1 to 4, characterized in that, The transfer function of the PIR regulator is shown in the following equation: In the formula, k p k is the proportional adjustment coefficient. i k is the integral adjustment coefficient. r ω is the resonance adjustment coefficient. c ω is the cutoff frequency, and ω0 is the resonant frequency.

6. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

7. A control system for a multi-rotor medium-pressure wind turbine generator set, comprising a computer device, the computer device including a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

Images