Method and system for simulating reactive characteristics of low voltage ride-through of direct-drive wind turbines

Abstract

The present invention provides a method and system for simulating reactive characteristics of a direct-drive wind turbine during low voltage ride-through. The system comprises: a control module during the low voltage ride-through period, which obtains a reactive current command value during the low voltage ride-through period according to a preset voltage calculation standard value, a reactive current calculation ratio, a low voltage ride-through trigger signal and a wind turbine terminal voltage; an active power recovery stage control module, which obtains a reactive current command value during the active power recovery period according to a preset reactive power reference value, a reactive power measurement value, a low voltage ride-through recovery trigger signal and a reactive power control mode during the active power recovery stage; a conventional stage control module, which obtains a conventional stage reactive current command value according to a preset reactive power reference value, a reactive power measurement value and a conventional stage signal; and a signal output module, which obtains and outputs a reactive current control command value. The present invention can accurately reproduce the reactive characteristics of an actual direct-drive wind turbine after low voltage ride-through.

Description

Technical Field

[0001] The present invention relates to the technical field of power system experiments, and in particular to a method and system for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine. Background Art

[0002] With the increasing application of wind turbines in power systems, obtaining accurate models of wind turbines has become an important task in the field of power system simulation. As a typical type of wind turbine, direct-drive wind turbines are increasingly used in wind farms across the country, so it is very important to accurately simulate direct-drive wind turbines. With the development of the power system, the grid connection requirements for direct-drive wind turbines are also being updated, especially the requirements for the low voltage ride-through characteristics of direct-drive wind turbines, which have changed significantly in recent years. Power grids in different regions even have different requirements. In order to cope with this change, it is necessary to accurately simulate the low voltage ride-through and recovery process of direct-drive wind turbines. The reactive characteristics of direct-drive wind turbines during low voltage ride-through have an important impact on the voltage stability of the power system, especially at the UHV DC sending end voltage. This characteristic directly determines the power transmission limit of the UHV DC project. Therefore, it is a very critical task to simulate the electromagnetic transient characteristics of the reactive power of direct-drive wind turbines during low voltage ride-through. Summary of the invention

[0003] One object of the present invention is to provide a method for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine, and to accurately reproduce the reactive characteristics of an actual direct-drive wind turbine after low voltage ride-through. Another object of the present invention is to provide a system for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine. Another object of the present invention is to provide a computer device. Another object of the present invention is to provide a readable medium.

[0004] In order to achieve the above objectives, the present invention discloses a direct-drive wind turbine low voltage ride-through reactive characteristic simulation system, comprising:

[0005] The low-voltage penetration stage control module is used to obtain the reactive current command value during the low-voltage penetration period according to the preset voltage calculation standard value, reactive current calculation ratio, low-voltage penetration trigger signal and the wind turbine terminal voltage;

[0006] Active power recovery stage control module, used to obtain reactive current command value during active power recovery according to preset reactive power reference value, reactive power measurement value, low-breakthrough recovery trigger signal and reactive power control mode during active power recovery stage;

[0007] A normal stage control module is used to obtain a normal stage reactive current command value according to a preset reactive reference value, a reactive measurement value and a normal stage signal;

[0008] The signal output module is used to obtain a reactive current control command value according to the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage.

[0009] Preferably, the low wear period stage control module comprises a first processing unit, a second processing unit and a third processing unit;

[0010] The first processing unit is used to calculate the difference between the voltage calculation standard value and the wind turbine terminal voltage to obtain a first processing result;

[0011] The second processing unit is used to calculate the product of the first processing result and the reactive current calculation ratio to obtain a second processing result;

[0012] The third processing unit is used to calculate the product of the second processing result and the low-breakthrough trigger signal to obtain the reactive current command value during the low-breakthrough period.

[0013] Preferably,

[0014] The first processing unit includes a first adder, the second processing unit includes a first multiplier, and the third processing unit includes a second multiplier;

[0015] Among them, the two signal input ends of the first adder are respectively used to receive the voltage calculation standard value and the wind turbine terminal voltage, the signal output end of the first adder is connected to the signal input end of the first multiplier, the signal output end of the first multiplier is connected to the signal input end of the second multiplier, and the signal output end of the second multiplier is used to output the reactive current command value during the low-power wear period.

[0016] Preferably, the active power recovery stage control module includes a first PI control unit, a mode input unit and an active power recovery control unit;

[0017] The first PI control unit is used to calculate the difference between the reactive reference value and the reactive measurement value and input the difference into a PI controller for PI regulation to obtain a first PI regulation signal;

[0018] The mode input unit is used to determine the reactive current control mode in the active power recovery stage according to the reactive power control mode in the active power recovery stage and the first PI adjustment signal;

[0019] The active power recovery control unit is used to multiply the reactive current control mode in the active power recovery stage by the low-breakdown recovery trigger signal to obtain the reactive current command value during the active power recovery period.

[0020] Preferably,

[0021] The first PI control unit includes a second adder, a third multiplier and a first PI controller, the mode input unit includes a signal selection circuit, and the active power recovery control unit includes a fourth multiplier;

[0022] The two signal input terminals of the second adder are respectively used to receive the reactive reference value and the reactive measurement value, the signal output terminal of the second adder is connected to the signal input terminal of the third multiplier, the signal output terminal of the third multiplier is connected to the signal input terminal of the first PI controller, the signal output terminal of the first PI controller is connected to a signal input terminal of the signal selection circuit, the other signal input terminal of the signal selection circuit is used to receive the reactive control mode in the active power recovery stage, the signal output terminal of the signal selection circuit is connected to a signal input terminal of the fourth multiplier, the other signal input terminal of the fourth multiplier is used to receive the low-breakthrough recovery trigger signal, and the signal output terminal of the fourth multiplier is used to output the reactive current command value during the active power recovery period.

[0023] Preferably, the conventional stage control module includes a second PI control unit and a conventional stage control unit;

[0024] The second PI control unit is used to calculate the difference between the reactive power reference value and the reactive power measurement value and input the difference into a PI controller for PI regulation to obtain a second PI regulation signal;

[0025] The normal stage control unit is used for multiplying the second PI regulation signal with the normal stage signal to obtain the normal stage reactive current command value.

[0026] Preferably, the second PI control unit includes a third adder, a fifth multiplier, a second PI controller and a sixth multiplier;

[0027] The two signal input terminals of the third adder are respectively used to receive the reactive reference value and the reactive measurement value, the signal output terminal of the third adder is connected to the signal input terminal of the fifth multiplier, the signal output terminal of the fifth multiplier is connected to the signal input terminal of the second PI controller, the signal output terminal of the second PI controller is connected to a signal input terminal of the sixth multiplier, the other signal input terminal of the sixth multiplier is used to receive the normal stage signal, and the signal output terminal of the sixth multiplier is used to output the normal stage reactive current command value.

[0028] Preferably, the signal output module is used to add the reactive current command value during the low-breakthrough period, the reactive current command value during the active power recovery period and the reactive current command value during the normal stage to obtain the reactive current control command value.

[0029] The present invention also discloses a method for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine, comprising:

[0030] The reactive current command value during the low penetration period is obtained according to the preset voltage calculation standard value, reactive current calculation ratio, low penetration trigger signal and wind turbine terminal voltage;

[0031] The reactive current command value during the active power recovery period is obtained according to the preset reactive power reference value, the reactive power measurement value, the low-breakthrough recovery trigger signal and the reactive power control mode during the active power recovery stage;

[0032] Obtaining a reactive current command value in a normal stage according to a preset reactive reference value, a reactive measurement value and a normal stage signal;

[0033] A reactive current control command value is obtained according to the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage.

[0034] Preferably, the step of obtaining the reactive current command value during the low penetration period according to the preset voltage calculation standard value, reactive current calculation ratio, low penetration trigger signal and wind turbine terminal voltage specifically includes:

[0035] Calculating the difference between the voltage calculation standard value and the wind turbine terminal voltage to obtain a first processing result;

[0036] Calculating the product of the first processing result and the reactive current calculation ratio to obtain a second processing result;

[0037] The product of the second processing result and the low-breakthrough trigger signal is calculated to obtain the reactive current command value during the low-breakthrough period.

[0038] Preferably, obtaining the reactive current command value during the active power recovery period according to the preset reactive power reference value, reactive power measurement value, low-breakthrough recovery trigger signal and reactive power control mode during the active power recovery stage specifically includes:

[0039] Calculating a difference between the reactive reference value and the reactive measurement value and inputting the difference into a PI controller for PI regulation to obtain a first PI regulation signal;

[0040] Determining a reactive current control mode in the active power recovery stage according to the reactive power control mode in the active power recovery stage and the first PI adjustment signal;

[0041] The reactive current control mode in the active power recovery phase is multiplied by the low-breakdown recovery trigger signal to obtain the reactive current command value during the active power recovery period.

[0042] Preferably, obtaining the reactive current command value in the normal stage according to the preset reactive reference value, the reactive measurement value and the normal stage signal specifically includes:

[0043] Calculating the difference between the reactive reference value and the reactive measurement value and inputting the difference into a PI controller for PI regulation to obtain a second PI regulation signal;

[0044] The second PI adjustment signal is multiplied by the normal stage signal to obtain the normal stage reactive current command value.

[0045] Preferably, obtaining the reactive current control command value according to the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage specifically includes:

[0046] The reactive current control command value is obtained by adding the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage.

[0047] The present invention proposes an electromagnetic transient characteristic simulation system for the reactive characteristics of a direct-drive wind turbine during low voltage ride-through. The reactive current command value during low voltage ride-through is obtained through the low voltage ride-through stage control module, the reactive current command value during active power recovery is obtained through the active power recovery stage control module, and the reactive current command value during the normal stage is obtained through the normal stage control module. Then, the reactive current control command value is obtained according to the reactive current command value during low voltage ride-through, the reactive current command value during active power recovery, and the reactive current command value during the normal stage as the output command of the entire system, which can accurately reproduce the reactive characteristics of the actual direct-drive wind turbine after low voltage ride-through. The present invention can be applied to the reactive characteristics analysis of direct-drive wind turbines during and after low voltage faults and the study of their impact on system stability, laying a solid foundation for studying the impact of direct-drive wind turbines on system voltage stability after being connected to the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 A structural diagram showing a specific embodiment of the low voltage ride-through reactive characteristic simulation system for a direct-drive wind turbine according to the present invention;

[0050] Figure 2 A structural diagram showing a low voltage ride-through stage control module of a specific embodiment of the direct-drive wind turbine low voltage ride-through reactive characteristic simulation system of the present invention;

[0051] Figure 3A circuit structure diagram of a low voltage ride-through period control module in a specific example of a direct-drive wind turbine low voltage ride-through reactive characteristic simulation system of the present invention is shown;

[0052] Figure 4 A structural diagram showing a control module in the active recovery phase of a specific embodiment of the low voltage ride-through reactive characteristic simulation system for a direct-drive wind turbine according to the present invention;

[0053] Figure 5 A circuit structure diagram of a control module in the active recovery phase in a specific example of a direct-drive wind turbine low voltage ride-through reactive characteristic simulation system according to the present invention is shown;

[0054] Figure 6 A structural diagram showing a conventional stage control module of a specific embodiment of a direct-drive wind turbine low voltage ride-through reactive characteristic simulation system of the present invention;

[0055] Figure 7 A circuit structure diagram of a conventional stage control module in a specific example of a direct-drive wind turbine low voltage ride-through reactive characteristic simulation system according to the present invention is shown;

[0056] Figure 8 A circuit structure diagram showing a signal output module in a specific example of the low voltage ride-through reactive characteristic simulation system for a direct-drive wind turbine according to the present invention;

[0057] Fig. 9 A comparison chart showing the test results of the direct-drive wind turbine low voltage ride-through reactive characteristic simulation system of the present invention and the RT-Lab experimental system under high wind conditions;

[0058] Fig.10 A comparison chart showing the test results of the direct-drive wind turbine low voltage ride-through reactive characteristic simulation system of the present invention and the RT-Lab experimental system under low wind conditions;

[0059] Fig.11 A flowchart showing a specific embodiment of the method for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine according to the present invention;

[0060] Fig.12 A flowchart showing a specific embodiment S100 of the method for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine according to the present invention;

[0061] Fig.13 A flowchart showing a specific embodiment S200 of the method for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine according to the present invention;

[0062] Fig.14 A flowchart showing a specific embodiment S300 of the method for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine according to the present invention;

[0063] Fig.15A flowchart showing a specific embodiment S400 of the method for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine according to the present invention;

[0064] Fig.16 A schematic diagram showing the structure of a computer device suitable for implementing an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0065] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] According to one aspect of the present invention, this embodiment discloses a direct-drive wind turbine low voltage ride-through reactive characteristic simulation system. In this embodiment, Figure 1 As shown, the simulation system includes a low-power-crossover stage control module 10 , an active power recovery stage control module 20 , a normal stage control module 30 and a signal output module 40 .

[0067] The low penetration period control module 10 is used to obtain the reactive current command value during the low penetration period according to the preset voltage calculation standard value, reactive current calculation ratio, low penetration trigger signal and wind turbine terminal voltage.

[0068] The active power recovery stage control module 20 is used to obtain the reactive current command value during the active power recovery period according to a preset reactive power reference value, reactive power measurement value, low-breakthrough recovery trigger signal and reactive power control mode of the active power recovery stage.

[0069] The normal stage control module 30 is used to obtain a normal stage reactive current command value according to a preset reactive reference value, a reactive measurement value and a normal stage signal.

[0070] The signal output module 40 is used to obtain a reactive current control command value according to the reactive current command value during the low-breakthrough period, the reactive current command value during the active power recovery period and the reactive current command value during the normal stage. The reactive current control command value Iq_ref can be transmitted to the direct-drive wind turbine for testing.

[0071] The electromagnetic transient characteristic simulation system of the reactive characteristic of the low voltage ride-through of a direct-drive wind turbine proposed in the present invention obtains the reactive current command value during the low voltage ride-through period through the low voltage ride-through period control module 10, obtains the reactive current command value during the active power recovery period through the active power recovery period control module 20, obtains the reactive current command value during the normal stage through the normal stage control module 30, and then obtains the reactive current control command value as the output command of the whole system according to the reactive current command value during the low voltage ride-through period, the reactive current command value during the active power recovery period and the reactive current command value during the normal stage, which can accurately reproduce the reactive characteristics of the actual direct-drive wind turbine after the low voltage ride-through. The present invention can be applied to the reactive characteristic analysis of the direct-drive wind turbine during and after the low voltage fault process and the study of its influence on the system stability, laying a solid foundation for studying the influence of the direct-drive wind turbine on the system voltage stability after being connected to the power system.

[0072] In a preferred embodiment, Figure 2 As shown, the low penetration period stage control module 10 includes a first processing unit 11, a second processing unit 12 and a third processing unit 13. The first processing unit 11 is used to calculate the difference between the voltage calculation standard value and the wind turbine terminal voltage to obtain a first processing result. The second processing unit 12 is used to calculate the product of the first processing result and the reactive current calculation ratio to obtain a second processing result. The third processing unit 13 is used to calculate the product of the second processing result and the low penetration trigger signal to obtain the reactive current command value during the low penetration period.

[0073] More preferably, the low wear period stage control module 10 can be implemented by a circuit structure. The circuit structure can be formed by various actual components or simulated by a software program. In a specific example, Figure 3 As shown, the first processing unit 11 includes a first adder, the second processing unit 12 includes a first multiplier, and the third processing unit 13 includes a second multiplier. The two signal input terminals of the first adder are respectively used to receive the voltage calculation standard value and the wind turbine terminal voltage, the signal output terminal of the first adder is connected to the signal input terminal of the first multiplier, the signal output terminal of the first multiplier is connected to the signal input terminal of the second multiplier, and the signal output terminal of the second multiplier is used to output the reactive current command value during the low-power wear period.

[0074] In this specific example, the working principle of the low wear period control module 10 is: the voltage difference (first processing result) is obtained by subtracting the actual wind turbine terminal voltage Vabc_B690_Mag from the voltage calculation standard value LVRT_u0 through the first adder. Among them, the voltage calculation standard value can be calculated according to the relevant standard formula I q ≥1.5×(0.9-U T)I n It is obtained that LVRT_u0 can usually be 0.9. Then, the first processing result is multiplied by the reactive current calculation ratio LVRT_iq_cof (generally not less than 1.5, which can be set according to experience) through the first multiplier to obtain the second processing result, and finally the second processing result is multiplied by the low penetration trigger signal LVRT_dur (obtained externally, when the direct-drive wind turbine enters the low penetration state, it is 1, and the rest of the time is 0), to obtain the output reactive current command value during the low penetration period.

[0075] In a preferred embodiment, Figure 4 As shown, the active power recovery stage control module 20 includes a first PI control unit 21, a mode input unit 22 and an active power recovery control unit 23. The first PI control unit 21 is used to calculate the difference between the reactive reference value and the reactive measurement value and input it into the PI controller for PI regulation to obtain a first PI regulation signal. The mode input unit 22 is used to determine the reactive current control mode of the active power recovery stage according to the reactive control mode of the active power recovery stage and the first PI regulation signal. The active power recovery control unit 23 is used to multiply the reactive current control mode of the active power recovery stage with the low-breakdown recovery trigger signal to obtain the reactive current command value during the active power recovery period.

[0076] More preferably, the active power recovery stage control module 20 can be implemented by a circuit structure. The circuit structure can be formed by various actual components or can be simulated by a software program. Figure 5 As shown, the first PI control unit 21 includes a second adder, a third multiplier and a first PI controller, the mode input unit 22 includes a signal selection circuit, and the active power recovery control unit 23 includes a fourth multiplier.

[0077] Among them, the two signal input ends of the second adder are respectively used to receive the reactive reference value and the reactive measurement value, the signal output end of the second adder is connected to the signal input end of the third multiplier, the signal output end of the third multiplier is connected to the signal input end of the first PI controller, the signal output end of the first PI controller is connected to a signal input end of the signal selection circuit, the other signal input end of the signal selection circuit is used to receive the reactive control mode in the active power recovery stage, the signal output end of the signal selection circuit is connected to a signal input end of the fourth multiplier, the other signal input end of the fourth multiplier is used to receive the low-breakthrough recovery trigger signal, and the signal output end of the fourth multiplier is used to output the reactive current command value during the active power recovery period.

[0078] In this specific example, the working principle of the active power recovery stage control module 20 is: first, the reactive reference value Qref is subtracted from the reactive measurement value Qmes by the second adder to obtain a difference, and the difference can be used as the input of the first PI controller. It should be noted that the limiting of the first PI controller of the current inner loop and the limiting of the modulation ratio of the modulation control may affect the effect of the reactive current tracking command value during the low wear period, and affect the jitter characteristics of the reactive power when the low wear exits. Secondly, according to the reactive control mode LVRT_Iq_Mode of the active power recovery stage and the signal selection circuit, the reactive current control mode of the active power recovery stage is selected. Some fans adopt the control mode of reactive current zero in the active power recovery stage, and some fans adopt the reactive current control mode of the conventional stage in the active power recovery stage. Which mode is selected is determined by the LVRT_Iq_Mode signal. At the same time, according to the first PI adjustment signal and the reactive control mode of the active power recovery stage, it is determined whether the signal selection circuit outputs the determined reactive current control mode of the active power recovery stage. Finally, the result selected by the signal selection circuit is multiplied by the low-voltage recovery trigger signal LVRT_recover (which can be obtained externally, which is 1 when the direct-drive wind turbine enters the low-voltage recovery state and 0 at other times) through the fourth multiplier to obtain the reactive current command value during the active power recovery period.

[0079] In a preferred embodiment, Figure 6 As shown, the conventional stage control module 30 includes a second PI control unit 31 and a conventional stage control unit 32. The second PI control unit 31 is used to calculate the difference between the reactive reference value and the reactive measurement value and input it into the PI controller for PI regulation to obtain a second PI regulation signal. The conventional stage control unit 32 is used to multiply the second PI regulation signal with the conventional stage signal to obtain the conventional stage reactive current command value.

[0080] More preferably, the conventional stage control module 30 can be implemented by a circuit structure. The circuit structure can be formed by various actual components or can be simulated by a software program. Figure 7 As shown, the second PI control unit 31 includes a third adder, a fifth multiplier, a second PI controller and a sixth multiplier. The two signal input ends of the third adder are respectively used to receive the reactive reference value and the reactive measurement value, the signal output end of the third adder is connected to the signal input end of the fifth multiplier, the signal output end of the fifth multiplier is connected to the signal input end of the second PI controller, the signal output end of the second PI controller is connected to a signal input end of the sixth multiplier, the other signal input end of the sixth multiplier is used to receive the normal stage signal, and the signal output end of the sixth multiplier is used to output the normal stage reactive current command value.

[0081] In this specific example, the working principle of the normal stage control module 30 is: the reactive reference value Qref is subtracted from the reactive measurement value Qmes by a third adder to obtain a difference, and the difference is used as the input of the second PI controller, and the second PI controller outputs a second PI adjustment signal according to the difference. It should be noted that the PI parameters of the second PI controller will affect the jitter characteristics of the reactive power when the low penetration exits. The second PI adjustment signal output by the second PI controller is multiplied by the normal stage signal LVRT_end (1 when the fan is not in the low penetration or low penetration recovery period, and 0 for the rest of the time), and the final normal stage reactive current command value is obtained as the output.

[0082] In a preferred embodiment, the signal output module 40 is used to add the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage to obtain the reactive current control command value.

[0083] More preferably, the signal output module 40 can be implemented by a circuit structure. The circuit structure can be formed by various actual components or can be simulated by a software program. Figure 8 As shown, the signal output module 40 includes a fourth adder. The three signal input terminals of the fourth adder are used to receive the reactive current command value during the low-breakthrough period, the reactive current command value during the active power recovery period and the reactive current command value during the normal stage to add and obtain the reactive current control command value.

[0084] It should be noted that the specific structures of some circuits in the present invention are not shown. Those skilled in the art can set the specific structures of the circuits as needed according to the functions implemented by each circuit. This is common knowledge in the art and will not be described in detail here.

[0085] The present invention is further illustrated by a specific example. In a simulation experiment, the direct-drive wind turbine low voltage ride-through reactive characteristic simulation system of the present invention is constructed by simulink simulation software and applied to the electromagnetic transient simulation system of the direct-drive wind turbine connected to the infinite power grid. Low voltage tests are carried out under high wind conditions and low wind conditions, respectively. The results obtained by using the direct-drive wind turbine low voltage ride-through reactive characteristic simulation system of the present invention are compared with the results obtained by the RT-Lab test based on the actual controller. The comparison results are shown in FIG. Fig. 9 and Fig.10 It can be seen from the simulation experiment results that the electromagnetic transient characteristic simulation system of the low voltage ride-through reactive characteristics of the direct-drive wind turbine proposed in the present invention can reproduce the characteristics of the RT-Lab physical controller, and then reproduce the reactive characteristics of the low voltage ride-through process of the actual direct-drive wind turbine controller.

[0086] Based on the same principle, this embodiment also discloses a method for simulating the reactive characteristics of a direct-drive wind turbine low voltage ride-through. Fig.11 As shown, in this embodiment, the method includes:

[0087] S100: Obtaining a reactive current command value during a low voltage penetration period according to a preset voltage calculation standard value, a reactive current calculation ratio, a low voltage penetration trigger signal and a wind turbine terminal voltage.

[0088] S200: Obtaining a reactive current command value during active power recovery according to a preset reactive power reference value, a reactive power measurement value, a low-breakthrough recovery trigger signal, and a reactive power control mode during an active power recovery phase.

[0089] S300: Obtaining a reactive current command value in a normal stage according to a preset reactive reference value, a reactive measurement value and a normal stage signal.

[0090] S400: Obtaining a reactive current control command value according to the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage.

[0091] In a preferred embodiment, Fig.12 As shown, the S100 may specifically include:

[0092] S110: Calculate the difference between the voltage calculation standard value and the wind turbine terminal voltage to obtain a first processing result.

[0093] S120: Calculate the product of the first processing result and the reactive current calculation ratio to obtain a second processing result.

[0094] S130: Calculate the product of the second processing result and the low-breakthrough trigger signal to obtain the reactive current command value during the low-breakthrough period.

[0095] In a preferred embodiment, Fig.13 As shown, the S200 may specifically include:

[0096] S210: Calculate the difference between the reactive reference value and the reactive measurement value and input the difference into a PI controller for PI regulation to obtain a first PI regulation signal.

[0097] S220: Determine a reactive current control method in the active power recovery stage according to the reactive power control mode in the active power recovery stage and the first PI adjustment signal.

[0098] S230: multiplying the reactive current control mode in the active power recovery stage by the low-breakdown recovery trigger signal to obtain a reactive current command value during the active power recovery period.

[0099] In a preferred embodiment, Fig.14 As shown, the S300 may specifically include:

[0100] S310: Calculate the difference between the reactive reference value and the reactive measurement value and input the difference into a PI controller for PI regulation to obtain a second PI regulation signal.

[0101] S320: Multiply the second PI adjustment signal by the normal stage signal to obtain the normal stage reactive current command value.

[0102] In a preferred embodiment, Fig.15 As shown, obtaining the reactive current control command value according to the reactive current command value during the low-breakthrough period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage in S400 may specifically include:

[0103] S410: Add the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage to obtain the reactive current control command value.

[0104] Since the principle of solving the problem by this method is similar to that of the above system, the implementation of this method can refer to the implementation of the system and will not be repeated here.

[0105] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer device, and specifically, the computer device may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0106] In a typical example, a computer device specifically includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the method described above is implemented when the processor executes the program.

[0107] Reference below Fig.16 , which shows a schematic diagram of the structure of a computer device 600 suitable for implementing an embodiment of the present application.

[0108] like Fig.16As shown, the computer device 600 includes a central processing unit (CPU) 601, which can perform various appropriate operations and processes according to a program stored in a read-only memory (ROM) 602 or a program loaded from a storage part 608 to a random access memory (RAM) 603. In the RAM 603, various programs and data required for the operation of the system 600 are also stored. The CPU 601, the ROM 602, and the RAM 603 are connected to each other via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0109] The following components are connected to the I / O interface 605: an input section 606 including a keyboard, a mouse, etc.; an output section 607 including a cathode ray tube (CRT), a liquid crystal feedback device (LCD), etc., and a speaker, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN card, a modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to the I / O interface 605 as needed. A removable medium 611, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 610 as needed, so that a computer program read therefrom is installed as needed as the storage section 608.

[0110] In particular, according to an embodiment of the present invention, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present invention includes a computer program product, which includes a computer program tangibly contained on a machine-readable medium, and the computer program includes program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through the communication part 609, and / or installed from the removable medium 611.

[0111] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0112] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0113] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0114] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0115] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0116] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0117] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0118] The present application may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The present application may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0119] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0120] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A direct-drive wind turbine low voltage ride-through reactive characteristic simulation system, characterized in that: The low-voltage penetration stage control module is used to obtain the reactive current command value during the low-voltage penetration period according to the preset voltage calculation standard value, reactive current calculation ratio, low-voltage penetration trigger signal and the wind turbine terminal voltage; Active power recovery stage control module, used to obtain reactive current command value during active power recovery according to preset reactive power reference value, reactive power measurement value, low-breakthrough recovery trigger signal and reactive power control mode during active power recovery stage; A normal stage control module is used to obtain a normal stage reactive current command value according to a preset reactive reference value, a reactive measurement value and a normal stage signal; A signal output module, used for obtaining a reactive current control command value according to the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage; The low wear period stage control module includes a first processing unit, a second processing unit and a third processing unit; The first processing unit is used to calculate the difference between the voltage calculation standard value and the wind turbine terminal voltage to obtain a first processing result; The second processing unit is used to calculate the product of the first processing result and the reactive current calculation ratio to obtain a second processing result; The third processing unit is used to calculate the product of the second processing result and the low-breakthrough trigger signal to obtain the reactive current command value during the low-breakthrough period.

2. The direct-drive wind turbine low voltage ride-through reactive characteristic simulation system according to claim 1 is characterized in that: The first processing unit includes a first adder, the second processing unit includes a first multiplier, and the third processing unit includes a second multiplier; Among them, the two signal input ends of the first adder are respectively used to receive the voltage calculation standard value and the wind turbine terminal voltage, the signal output end of the first adder is connected to the signal input end of the first multiplier, the signal output end of the first multiplier is connected to the signal input end of the second multiplier, and the signal output end of the second multiplier is used to output the reactive current command value during the low-power wear period.

3. The direct-drive wind turbine low voltage ride-through reactive characteristic simulation system according to claim 1 is characterized in that: The active power recovery stage control module includes a first PI control unit, a mode input unit and an active power recovery control unit; The first PI control unit is used to calculate the difference between the reactive reference value and the reactive measurement value and input the difference into a PI controller for PI regulation to obtain a first PI regulation signal; The mode input unit is used to determine the reactive current control mode in the active power recovery stage according to the reactive power control mode in the active power recovery stage and the first PI adjustment signal; The active power recovery control unit is used to multiply the reactive current control mode in the active power recovery stage by the low-breakdown recovery trigger signal to obtain the reactive current command value during the active power recovery period.

4. The direct-drive wind turbine low voltage ride-through reactive characteristic simulation system according to claim 3 is characterized in that: The first PI control unit includes a second adder, a third multiplier and a first PI controller, the mode input unit includes a signal selection circuit, and the active power recovery control unit includes a fourth multiplier; The two signal input terminals of the second adder are respectively used to receive the reactive reference value and the reactive measurement value, the signal output terminal of the second adder is connected to the signal input terminal of the third multiplier, the signal output terminal of the third multiplier is connected to the signal input terminal of the first PI controller, the signal output terminal of the first PI controller is connected to a signal input terminal of the signal selection circuit, the other signal input terminal of the signal selection circuit is used to receive the reactive control mode in the active power recovery stage, the signal output terminal of the signal selection circuit is connected to a signal input terminal of the fourth multiplier, the other signal input terminal of the fourth multiplier is used to receive the low-breakthrough recovery trigger signal, and the signal output terminal of the fourth multiplier is used to output the reactive current command value during the active power recovery period.

5. The direct-drive wind turbine low voltage ride-through reactive characteristic simulation system according to claim 1 is characterized in that: The conventional stage control module includes a second PI control unit and a conventional stage control unit; The second PI control unit is used to calculate the difference between the reactive power reference value and the reactive power measurement value and input the difference into a PI controller for PI regulation to obtain a second PI regulation signal; The normal stage control unit is used for multiplying the second PI regulation signal with the normal stage signal to obtain the normal stage reactive current command value.

6. The direct-drive wind turbine low voltage ride-through reactive characteristic simulation system according to claim 5 is characterized in that: The second PI control unit includes a third adder, a fifth multiplier, a second PI controller and a sixth multiplier; The two signal input terminals of the third adder are respectively used to receive the reactive reference value and the reactive measurement value, the signal output terminal of the third adder is connected to the signal input terminal of the fifth multiplier, the signal output terminal of the fifth multiplier is connected to the signal input terminal of the second PI controller, the signal output terminal of the second PI controller is connected to a signal input terminal of the sixth multiplier, the other signal input terminal of the sixth multiplier is used to receive the normal stage signal, and the signal output terminal of the sixth multiplier is used to output the normal stage reactive current command value.

7. The direct-drive wind turbine low voltage ride-through reactive characteristic simulation system according to claim 1, characterized in that: The signal output module is used to add the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage to obtain the reactive current control command value.

8. A method for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine, characterized in that: include: The reactive current command value during the low penetration period is obtained according to the preset voltage calculation standard value, reactive current calculation ratio, low penetration trigger signal and wind turbine terminal voltage; The reactive current command value during the active power recovery period is obtained according to the preset reactive power reference value, the reactive power measurement value, the low-breakthrough recovery trigger signal and the reactive power control mode during the active power recovery stage; Obtaining a reactive current command value in a normal stage according to a preset reactive reference value, a reactive measurement value and a normal stage signal; Obtaining a reactive current control command value according to the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage; The method of obtaining the reactive current command value during the low penetration period according to the preset voltage calculation standard value, reactive current calculation ratio, low penetration trigger signal and wind turbine terminal voltage specifically includes: Calculating the difference between the voltage calculation standard value and the wind turbine terminal voltage to obtain a first processing result; Calculating the product of the first processing result and the reactive current calculation ratio to obtain a second processing result; The product of the second processing result and the low-breakthrough trigger signal is calculated to obtain the reactive current command value during the low-breakthrough period.

9. The method for simulating reactive characteristics of low voltage ride-through of a direct-drive wind turbine according to claim 8, characterized in that: The method of obtaining the reactive current command value during the active power recovery period according to the preset reactive power reference value, reactive power measurement value, low-breakthrough recovery trigger signal and reactive power control mode during the active power recovery period specifically includes: Calculating a difference between the reactive reference value and the reactive measurement value and inputting the difference into a PI controller for PI regulation to obtain a first PI regulation signal; Determining a reactive current control mode in the active power recovery stage according to the reactive power control mode in the active power recovery stage and the first PI adjustment signal; The reactive current control mode in the active power recovery phase is multiplied by the low-breakdown recovery trigger signal to obtain the reactive current command value during the active power recovery period.

10. The method for simulating reactive characteristics of low voltage ride through of a direct-drive wind turbine according to claim 8, characterized in that: The method of obtaining the reactive current command value in the normal stage according to the preset reactive reference value, the reactive measurement value and the normal stage signal specifically includes: Calculating the difference between the reactive reference value and the reactive measurement value and inputting the difference into a PI controller for PI regulation to obtain a second PI regulation signal; The second PI adjustment signal is multiplied by the normal stage signal to obtain the normal stage reactive current command value.

11. The method for simulating reactive characteristics of low voltage ride through of a direct-drive wind turbine according to claim 8, characterized in that: The step of obtaining the reactive current control command value according to the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage specifically includes: The reactive current control command value is obtained by adding the reactive current command value during the low-power break-through period, the reactive current command value during the active power recovery period, and the reactive current command value during the normal stage.

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