Double-fed wind turbine converter parameter test system based on step-by-step small-signal of each link

Abstract

The present invention provides a double-fed wind turbine converter parameter testing system based on sub-link small-signal step, including: a simulation platform, a small-signal superposition and holding module, a hardware device of a wind turbine converter controller, and a host computer. Among them: the simulation platform is used to simulate a double-fed wind turbine grid-connected operation model; the host computer is used to modify the structure and parameters of the double-fed wind turbine grid-connected operation model in the simulation platform, realize the compilation and startup of the double-fed wind turbine grid-connected operation model, and is used to issue control instructions to the hardware device of the wind turbine converter controller to realize the sequential startup and grid-connected operation of the double-fed wind turbine converter, and is also used to control the small-signal superposition and holding module to realize sub-link small-signal step. The present invention enables testers to divide whether the analog input quantity of the wind turbine controller undergoes a step, thereby realizing the sub-link input small-signal step of the wind turbine converter controller, and can complete the identification test of the control parameters of the double-fed wind turbine converter through the small-signal step.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power, and particularly to a parameter testing system for a doubly-fed wind turbine converter based on sub-link small-signal step. Background Art

[0002] With the acceleration of the pace of regional energy clean and low-carbon transformation, the rapid development of large-scale new energy power generation, the dynamic characteristics of the power system have gradually changed from the electromechanical transient process dominated by traditional thermal power units to the electromagnetic-electromechanical transient process jointly affected by a high proportion of new energy and traditional thermal power units. Therefore, in-depth study of the grid-connected characteristics of new energy units and their dynamic interaction with the power grid is of great significance to the safe and stable operation of large power grids.

[0003] Hardware-in-the-loop testing refers to the process of establishing a closed-loop test circuit for the actual controller device and the controlled object, enabling the controller to receive the state of the controlled object and issue control commands, and then obtaining the feedback state quantity of the controlled object and issuing control commands again. At present, there are not many studies on the hardware-in-the-loop testing of the control parameters of doubly-fed wind turbine converters in the new energy field. The invention patent with the application publication number CN106199193A discloses a hardware-in-the-loop testing system and method for the impedance of a doubly-fed wind turbine, which discloses that by modifying the settings of the small-signal voltage source and frequency, the harmonic characteristics of the external power supply are changed, thereby exciting and obtaining the corresponding harmonic current response of the doubly-fed wind turbine, and thus obtaining the impedance characteristics of the wind turbine at different frequency points. However, this invention cannot achieve the sub-link input small-signal step of the wind turbine converter controller, so the identification test of the control parameters of the doubly-fed wind turbine cannot be carried out. Summary of the Invention

[0004] In view of this, the present invention provides a parameter testing system for a doubly-fed wind turbine converter based on sub-link small-signal step to solve at least one of the above-mentioned problems.

[0005] To achieve the above object, the present invention adopts the following solutions:

[0006] According to the first aspect of the present invention, an embodiment of the present invention provides a double-fed wind turbine converter parameter test system based on segmented small-signal step. The system includes: a simulation platform, a small-signal superposition and holding module, a hardware device of a wind turbine converter controller, and a host computer. The host computer is respectively connected to the simulation platform, the small-signal superposition and holding module, and the hardware device of the wind turbine converter controller. The small-signal superposition and holding module is also respectively connected to the simulation platform and the hardware device of the wind turbine converter controller. The hardware device of the wind turbine converter controller is also connected to the simulation platform, where: the simulation platform is used to simulate and model the grid-connected operation of a double-fed wind turbine; the host computer is used to modify the structure and parameters of the grid-connected operation model of the double-fed wind turbine in the simulation platform, realize the compilation and start of the grid-connected operation model of the double-fed wind turbine, and is used to send control commands to the hardware device of the wind turbine converter controller to realize the sequential start and grid-connected operation of the double-fed wind turbine converter, and is also used to control the small-signal superposition and holding module to realize segmented small-signal step.

[0007] Preferably, the simulation platform in the above system of this embodiment includes: a wind turbine generator module, an induction motor module, a machine-side converter module, a grid-side converter module, a box-type step-up transformer module, and an equivalent module of an AC power grid. The wind turbine generator module, the induction motor module, the box-type step-up transformer module, and the equivalent module of the AC power grid are connected in sequence. The machine-side converter module is respectively connected to the induction motor module and the grid-side converter module. The grid-side converter module is connected to the box-type step-up transformer module.

[0008] Preferably, the above system of this embodiment further includes an analog output board card, a digital output board card, and a digital input board card. The analog output board card is respectively connected to the simulation platform and the small-signal superposition and holding module. The digital output board card and the digital input board card are respectively connected to the simulation platform and the hardware device of the wind turbine converter controller, where: the analog output board card outputs the grid-side three-phase voltage and / or current, DC bus voltage, machine-side three-phase voltage and / or current, and high-frequency speed encoder pulse signal of the grid-connected operation model of the double-fed wind turbine to the small-signal superposition and holding module; the digital output board card outputs the opening and closing state quantities of the stator-side grid-connected switch and the grid-side converter grid-connected switch to the hardware device of the wind turbine converter controller; the digital input board card inputs the high-frequency pulse trigger signal and switch control signal of the converter to the grid-connected operation model of the double-fed wind turbine.

[0009] Preferably, in the above system of this embodiment, the small-signal superposition and holding module includes: a direct-through channel, a step channel, a power holding channel, and a signal holding channel. The direct-through channel is used to directly output the input analog quantity. The step channel is used to output the input analog quantity after performing a small-signal step in sub-links. The power holding channel is used to ensure that the power of the output signal remains the same as the power of the input analog quantity. The signal holding channel is used to make the output signal passing through the signal holding channel at present have the same amplitude, phase, and frequency as the input analog quantity signal input to the small-signal superposition and holding module before the specified time T0.

[0010] Preferably, in the above system of this embodiment, the host computer controls the input analog quantity to enter the direct-through channel, the step channel, the power holding channel, or the signal holding channel according to the simulation requirements.

[0011] Preferably, in the above system of this embodiment, the step channel includes a first signal decomposition sub-module, a small-signal step sub-module, and a signal synthesis sub-module. The first signal decomposition sub-module, the small-signal step sub-module, and the signal synthesis sub-module are connected in sequence. Among them: the first signal decomposition sub-module is used to perform Fourier decomposition on the input analog quantity signal to obtain the amplitude and phase of each frequency point; the small-signal step sub-module is used to perform an up-step or down-step of A% amplitude on the analog quantity signal at time T0 according to the step amplitude A%, step time T0, and step direction set by the host computer; the signal synthesis sub-module is used to superimpose and synthesize signals of different frequencies and then output.

[0012] Preferably, in the above system of this embodiment, the host computer realizes the identification test of the control parameters of the doubly-fed wind turbine converter by controlling the switching of the input analog quantity among the direct-through channel, the step channel, the power holding channel, and the signal holding channel.

[0013] Preferably, in the above system of this embodiment, the identification test of the control parameters of the doubly-fed wind turbine converter includes the identification of the d-axis current inner-loop parameters of the grid-side converter and the identification of the DC voltage outer-loop parameters.

[0014] Preferably, in the above system of this embodiment, when the identification test of the control parameters of the doubly-fed wind turbine converter is the identification of the d-axis current inner-loop parameters of the grid-side converter, the implementation process is as follows: Through the host computer, the DC voltage analog quantity in the small-signal superposition and holding module is switched from the direct-through quantity to the signal holding quantity, and the sampled three-phase AC current analog quantity of the grid-side converter is switched from the direct-through quantity to the step quantity to be set. The step amplitude is set to A% (A ≤ 10), the step frequency is 50 Hz, and the step direction is up or down; at time T0, the host computer is used to implement the signal holding of the DC voltage analog quantity and the step of the sampled three-phase AC current analog quantity of the grid-side converter in the set step direction, and record the step waveform of the sampled three-phase AC current analog quantity of the grid-side converter; based on the phase angle of the grid-side power supply, the sampled three-phase AC current analog quantity of the grid-side converter is subjected to DQ decomposition to obtain the step waveforms of the d-axis and q-axis currents in its DQ coordinates, and based on the rise time, adjustment time, peak time, and overshoot of the step waveforms of the d-axis and q-axis currents, the proportional coefficient kp and integral coefficient ki of the d-axis current inner loop are identified.

[0015] Preferably, in the above system of this embodiment, when the identification test of the control parameters of the doubly-fed wind turbine converter is the identification of the DC voltage outer-loop parameters, the implementation process is as follows: Through the host computer, the sampled three-phase AC current analog quantity of the grid-side converter in the small-signal superposition and holding module is switched from the step quantity to be set to the direct-through quantity, and the DC voltage analog quantity is switched from the signal holding quantity to the step quantity to be set. At the same time, the step amplitude is set to B% (B ≤ 10, and it is necessary to ensure that the DC voltage amplitude after the step does not meet the start condition of the DC bus CHOPPER circuit), the step frequency is 0 Hz, and the step direction is up or down; at time T0, the host computer is used to implement the step of the DC voltage analog quantity in the set step direction, record the DC voltage step waveform, and based on the rise time, adjustment time, peak time, and overshoot of the DC voltage step waveform, the proportional coefficient kp and integral coefficient ki of the DC voltage outer loop are identified.

[0016] Preferably, in the above system of this embodiment, the power holding channel includes a second signal decomposition sub-module, a first signal holding sub-module, and a power holding sub-module. The first signal holding sub-module is respectively connected to the second signal decomposition sub-module and the power holding sub-module. The power holding sub-module is further connected to the small-signal step sub-module, where: the second signal decomposition sub-module is used to perform Fourier decomposition on the input analog signal to obtain the amplitude and phase of each frequency point; the first signal holding sub-module is used to store, save, and synthesize the amplitude and phase of each frequency point output by the second signal decomposition sub-module according to the command signal of the host computer, so that the output signal currently passing through the first signal holding sub-module is the same as the analog input signal input to the small-signal superposition and holding module at time T0; the power holding sub-module is used to keep the power value of the input analog signal passing through the power holding channel unchanged, and to keep the corresponding power value unchanged after the required step analog signal undergoes a small-signal step.

[0017] Preferably, in the above system of this embodiment, the signal holding channel includes a third signal decomposition sub-module and a second signal holding sub-module. The third signal decomposition sub-module is connected to the second signal holding sub-module, where: the third signal decomposition sub-module is used to perform Fourier decomposition on the input analog signal to obtain the amplitude and phase of each frequency point; the second signal holding sub-module is used to store, save, and synthesize the amplitude and phase of each frequency point output by the second signal decomposition sub-module according to the command signal of the host computer, so that the output signal currently passing through the first signal holding sub-module is the same as the analog input signal input to the small-signal superposition and holding module at time T0.

[0018] Preferably, the simulation platform in the above system of this embodiment is a real-time digital simulation system RTDS platform.

[0019] The double-fed wind turbine converter parameter test system based on the small-signal step of sub-links proposed by the present invention can control the analog additional small-signal superposition and holding module output by the double-fed wind turbine grid-connected operation model in the simulation platform through the host computer, so that the tester can manually program or manually divide whether the analog input to the wind turbine controller undergoes a step, thereby realizing the small-signal step of the sub-link input of the wind turbine converter controller, and can complete the identification test of the control parameters of the double-fed wind turbine converter through the small-signal step. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. In the drawings:

[0021] Figure 1 is a schematic structural diagram of a double-fed wind turbine converter parameter test system based on sub-link small-signal step provided by an embodiment of the present application;

[0022] Figure 2 is a schematic structural diagram of a simulation platform provided by an embodiment of the present application;

[0023] Figure 3 is a schematic structural diagram of a double-fed wind turbine converter parameter test system based on sub-link small-signal step provided by another embodiment of the present application;

[0024] Figure 4 is a schematic structural diagram of a small-signal superposition and holding module provided by an embodiment of the present application. Detailed implementation manners

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer and more understandable, the following further elaborates on the embodiments of the present invention in conjunction with the drawings. Herein, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but do not limit the present invention.

[0026] As Figure 1 shown is a schematic structural diagram of a double-fed wind turbine converter parameter test system based on sub-link small-signal step provided by an embodiment of the present application. The system includes: a simulation platform 100, a small-signal superposition and holding module 200, a hardware device 300 of a wind turbine converter controller, and a host computer 400. It can be Figure 1 seen that the host computer 400 is respectively connected to the simulation platform 100, the small-signal superposition and holding module 200, and the hardware device 300 of the wind turbine converter controller. The small-signal superposition and holding module 200 is also respectively connected to the simulation platform 100 and the hardware device 300 of the wind turbine converter controller, and the hardware device 300 of the wind turbine converter controller is also connected to the simulation platform 100.

[0027] In this embodiment, the simulation platform 100 is used to simulate the grid-connected operation model of a doubly-fed wind turbine, which is a grid-connected operation model of a doubly-fed wind turbine established according to the actual parameters provided by the manufacturer. Preferably, in this embodiment, the simulation platform 100 can be constructed by a real-time digital simulation system (real-time digital simulation system, RTDS).

[0028] Preferably, as Figure 2 shown, the simulation platform 100 may include: a wind turbine generator module 110, an induction motor module 120, a machine-side converter module 130, a grid-side converter module 140, a box-type step-up transformer module 150, and an AC grid equivalent module 160. Among them, the wind turbine generator module 110, the induction motor module 120, the box-type step-up transformer module 150, and the AC grid equivalent module 160 are connected in sequence. The machine-side converter module 130 is respectively connected to the induction motor module 120 and the grid-side converter module 140, and the grid-side converter module 140 is connected to the box-type step-up transformer module 150, which can simulate the grid-connected operation of a wind power generation system.

[0029] The host computer 400 is used to modify the structure and parameters of the grid-connected operation model of the doubly-fed wind turbine in the simulation platform 100, implement the compilation and startup of the grid-connected operation model of the doubly-fed wind turbine, and issue control commands to the hardware device 300 of the wind turbine converter controller to realize the sequential startup and grid-connected operation of the doubly-fed wind turbine converter. It is also used to control the small-signal superposition and hold module 200 to realize the small-signal step of each link.

[0030] As described above, the parameter test system for the doubly-fed wind turbine converter based on the small-signal step of each link proposed by the present invention can control the analog quantity output by the grid-connected operation model of the doubly-fed wind turbine in the simulation platform through the host computer to add a small-signal superposition and hold module, so that the tester can manually program or manually divide whether the analog quantity input to the wind turbine controller undergoes a step, thereby realizing the small-signal step of the input of each link of the wind turbine converter controller, and can complete the identification test of the control parameters of the doubly-fed wind turbine converter through the small-signal step.

[0031] As Figure 3 shown is a schematic structural diagram of a parameter test system for a doubly-fed wind turbine converter based on the small-signal step of each link provided by another embodiment of the present application. Figure 3It can be seen that the system further includes an analog output (GTAO) board 510, a digital output (GTDO) board 520, and a digital input (GTDI) board 530. The GTAO board 510 is respectively connected to the simulation platform 100, the small-signal superposition and hold module 200. The GTDO board 520 and the GTDI board 530 are respectively connected to the simulation platform 100 and the wind turbine converter controller hardware device 300.

[0032] The GTAO board 510 outputs the grid-side three-phase voltage and / or current, DC bus voltage, machine-side three-phase voltage and / or current, and high-frequency speed encoder pulse signal of the doubly-fed wind turbine grid-connected operation model in the simulation platform 100 to the small-signal superposition and hold module 200, and its analog output is the input analog quantity of the small-signal superposition and hold module 200.

[0033] The GTDO board 520 outputs the on / off status quantities (digital quantities) of the stator-side grid-connected switch and the grid-side converter grid-connected switch to the wind turbine converter controller hardware device 300.

[0034] The GTDI board 530 inputs the converter high-frequency pulse trigger signal and switch control signal output by the wind turbine converter controller hardware device 300 to the doubly-fed wind turbine grid-connected operation model.

[0035] Preferably, in this embodiment, the small-signal superposition and hold module 200 may include four channels: a direct-through channel, a step channel, a power hold channel, and a signal hold channel. The direct-through channel is used to directly output the input analog quantity (i.e., the output quantity of the GTAO board 510). The step channel is used to output the input analog quantity after performing a step of small-signal in sub-links. The power hold channel is used to ensure that the power of the output signal remains the same as the power of the input analog quantity. The signal hold channel is used to make the output signal passing through the signal hold channel at present the same as the input analog quantity signal input to the small-signal superposition and hold module at the specified time T0.

[0036] In this embodiment, the host computer 400 can control the input analog quantity to enter the above-mentioned direct-through channel, step channel, power hold channel, or signal hold channel according to the simulation requirements. Specifically, the input analog quantity can be divided into a step quantity, a power hold quantity, a signal hold quantity, and a direct-through quantity according to the simulation requirements. When the input analog quantity is a step quantity, the host computer 400 controls the input analog quantity to enter the step channel; when the input analog quantity is a power hold quantity, the host computer 400 controls the input analog quantity to enter the power hold channel; when the input analog quantity is a signal hold quantity, the host computer 400 controls the input analog quantity to enter the signal hold channel; when the input analog quantity is a direct-through quantity, the host computer 400 controls the input analog quantity to enter the direct-through channel.

[0037] Such asFigure 4 The following is a schematic structural diagram of a small-signal superposition and holding module provided by an embodiment of the present application. Figure 4 As can be seen, the four input analog quantities, namely the step quantity to be processed, the power holding quantity, the signal holding quantity, and the direct-through quantity, can be processed and output through different channels.

[0038] The direct-through quantity does not need to be processed and can directly output the input analog quantity.

[0039] The step quantity to be processed needs to be processed and output through the step channel. In this embodiment, the step channel includes a first signal decomposition sub-module 201, a small-signal step sub-module 202, and a signal synthesis sub-module 203, which are connected in sequence.

[0040] The first signal decomposition sub-module 201 is used to perform Fourier decomposition on the input analog quantity signal to obtain the amplitude and phase of each frequency point. The small-signal step sub-module 202 is used to perform an up-step or down-step of the amplitude of A% on the analog quantity signal at the moment T0 according to the step amplitude A%, step moment T0, and step direction set by the host computer 400. The signal synthesis sub-module 203 is used to superimpose and synthesize signals of different frequencies and then output them.

[0041] The power holding quantity needs to be processed and output through the power holding channel. In this embodiment, the power holding channel includes a second signal decomposition sub-module 204, a first signal holding sub-module 205, and a power holding sub-module 206, which are connected in sequence, and the power holding sub-module 206 is also connected to the above-mentioned small-signal step sub-module 202.

[0042] The function of the second signal decomposition sub-module 204 is the same as that of the first signal decomposition sub-module 201, and it is also used to perform Fourier decomposition on the input analog quantity signal to obtain the amplitude and phase of each frequency point.

[0043] The first signal holding sub-module 205 is used to store, save, and synthesize the amplitudes and phases of each frequency point output by the second signal decomposition sub-module 204 according to the command signal from the host computer 400, so that the output signal passing through the first signal holding sub-module 205 currently has the same amplitude, phase, and frequency as the analog input signal input to the small-signal superposition and holding module 200 before time T0. The power holding sub-module 206 is used to keep the power value of the input analog signal passing through the power holding channel unchanged, and to keep the corresponding power value unchanged after a small-signal step of the analog signal to be stepped. For example, if the step amount is the stator voltage sampling signal, then the power holding amount is the stator current sampling signal at this time. If it is necessary to keep the stator output power calculated by sampling unchanged after the stator voltage step, then the stator current held before the step can be stepped with equal amplitude in the opposite direction after the stator voltage step, so that the stator power remains unchanged before and after the step.

[0044] Similarly, the signal holding amount needs to be processed and output through the signal holding channel. In this embodiment, the signal holding channel includes a third signal decomposition sub-module 207 and a second signal holding sub-module 208, where the third signal decomposition sub-module 207 and the second signal holding sub-module 208 are connected.

[0045] The third signal decomposition sub-module 207 is used to perform Fourier decomposition on the input analog signal to obtain the amplitudes and phases of each frequency point.

[0046] The second signal holding sub-module 208 is used to store, save, and synthesize the amplitudes and phases of each frequency point output by the third signal decomposition sub-module 207 according to the command signal from the host computer 400, so that the output signal passing through the second signal holding sub-module 208 currently has the same amplitude, phase, and frequency as the analog input signal input to the small-signal superposition and holding module 200 before time T0.

[0047] It should be noted that the functions of the above-mentioned first signal decomposition module 201, second signal decomposition module 204, and third signal decomposition sub-module 207 are the same, and the functions of the first signal holding sub-module 205 and the second signal holding sub-module 208 are also the same. In specific implementation, the same function can be implemented by the same module, and channel selection logic can be added inside for signal distribution.

[0048] In this embodiment, the doubly-fed wind turbine converter in-loop test system provided by the present application can realize the identification test of the control parameters of the doubly-fed wind turbine converter. Specifically, the host computer 400 realizes the identification test of the control parameters of the doubly-fed wind turbine converter by controlling the switching of the input analog quantity among the direct-through quantity channel, step channel, power holding channel, and signal holding channel.

[0049] The following takes the identification of the d-axis current inner-loop parameters and the identification of the DC voltage outer-loop parameters of the grid-side converter as examples to further illustrate the identification test of the control parameters of the doubly-fed wind turbine converter, which may include the following steps:

[0050] Step 1: Based on Figure 3 Build a hardware-in-the-loop simulation test platform for the doubly-fed wind turbine converter control. Among them, all the small-signal superposition and hold modules 200 are selected as the through-put input mode, that is, all the input analog quantities are directly output to the wind turbine converter controller, and the grid-side power supply adopts an infinite power supply model.

[0051] Step 2: Start the simulation model in the simulation platform 100 and the hardware device 300 of the wind turbine converter controller through the host computer 400 to realize the sequential start of the grid-side converter module 140 and the machine-side converter module 130 of the wind turbine and the grid connection operation of the wind turbine.

[0052] Step 3: Send control commands to the wind turbine converter controller through the host computer, so that the wind turbine operates in parallel and outputs rated active power and zero reactive power.

[0053] The above Steps 1-Step 3 are the preparatory work before parameter identification.

[0054] Step 4: Through the host computer 400, switch the DC voltage analog quantity in the small-signal superposition and hold module 200 from the through-put quantity to the signal hold quantity, switch the sampled three-phase AC current analog quantity of the grid-side converter from the through-put quantity to the step quantity to be set, set the step amplitude to A% (A≤10), the step frequency to 50Hz, and the step direction to up or down step.

[0055] Step 5: At time T0, through the host computer 400, realize the signal hold of the DC voltage analog quantity and the step of the sampled three-phase AC current analog quantity of the grid-side converter in the set step direction, and record the step waveform of the sampled three-phase AC current analog quantity of the grid-side converter.

[0056] Step 6: Based on the phase angle of the grid-side power supply, perform DQ decomposition on the sampled three-phase AC current analog quantity of the grid-side converter to obtain the step waveforms of the d-axis and q-axis currents in the DQ coordinate system. Based on the rise time, adjustment time, peak time, and overshoot of the step waveforms of the d-axis and q-axis currents, identify the proportional coefficient kp and the integral coefficient ki of the d-axis current inner loop.

[0057] Step 7: Through the host computer 400, switch the sampled three-phase AC current analog quantity of the grid-side converter in the small-signal superposition and hold module 200 from the required step quantity to the through quantity, and switch the DC voltage analog quantity from the signal hold quantity to the required step quantity. At the same time, set the step amplitude to B% (B ≤ 10, and it is necessary to ensure that the DC voltage amplitude after the step does not meet the starting condition of the DC bus CHOPPER circuit), the step frequency to 0 Hz, and the step direction to up or down step.

[0058] Step 8: At time T0, through the host computer 400, step the DC voltage analog signal in the set step direction, record the DC voltage step waveform, and identify the proportional coefficient kp and integral coefficient ki of the DC voltage outer loop based on the rise time, adjustment time, peak time, and overshoot of the DC voltage step waveform.

[0059] It can be seen that through the above steps 4-6, the parameter identification of the d-axis current inner loop of the grid-side converter can be realized, and through steps 7-8, the parameter identification of the DC voltage outer loop can be realized.

[0060] The parameter test system of the doubly-fed wind turbine converter based on the small-signal step by sub-link proposed by the present invention can control the analog quantity additional small-signal superposition and hold module output by the doubly-fed wind turbine grid-connected operation model in the simulation platform through the host computer, so that the tester can manually program or manually divide whether the analog quantity input to the wind turbine controller undergoes a step, so as to realize the small-signal step of the sub-link input of the wind turbine converter controller, and can complete the identification test of the control parameters of the doubly-fed wind turbine converter by realizing the small-signal step.

[0061] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A parameter testing system for a doubly-fed wind turbine converter based on segmented small-signal step, characterized in that, the system includes: a simulation platform, a small-signal superposition and holding module, a hardware device of a wind turbine converter controller, and a host computer. The host computer is respectively connected to the simulation platform, the small-signal superposition and holding module, and the hardware device of the wind turbine converter controller. The small-signal superposition and holding module is also respectively connected to the simulation platform and the hardware device of the wind turbine converter controller. The hardware device of the wind turbine converter controller is also connected to the simulation platform, where: the simulation platform is used to simulate the grid-connected operation model of a doubly-fed wind turbine; the host computer is used to modify the structure and parameters of the grid-connected operation model of the doubly-fed wind turbine in the simulation platform, implement the compilation and startup of the grid-connected operation model of the doubly-fed wind turbine, and is used to send control commands to the hardware device of the wind turbine converter controller to achieve the sequential startup and grid-connected operation of the doubly-fed wind turbine converter, and is also used to control the small-signal superposition and holding module to achieve segmented small-signal step; the small-signal superposition and holding module includes: a direct-through channel, a step channel, a power holding channel, and a signal holding channel. The direct-through channel is used to directly output the input analog quantity. The step channel is used to output the input analog quantity after segmented small-signal step. The power holding channel is used to ensure that the power of the output signal remains the same as the power of the input analog quantity. The signal holding channel is used to make the output signal passing through the signal holding channel at present have the same amplitude, phase, and frequency as the input analog quantity signal input to the small-signal superposition and holding module before the specified T0 moment; the host computer is also used to identify and test the control parameters of the doubly-fed wind turbine converter by controlling the switching of the input analog quantity among the direct-through channel, the step channel, the power holding channel, and the signal holding channel.

2. The parameter testing system for a doubly-fed wind turbine converter based on segmented small-signal step according to claim 1, characterized in that, the simulation platform includes: a wind turbine generator module, an induction motor module, a machine-side converter module, a grid-side converter module, a box-type step-up transformer module, and an AC grid equivalent module. The wind turbine generator module, the induction motor module, the box-type step-up transformer module, and the AC grid equivalent module are connected in sequence. The machine-side converter module is respectively connected to the induction motor module and the grid-side converter module. The grid-side converter module is connected to the box-type step-up transformer module.

3. The parameter testing system for a doubly-fed wind turbine converter based on segmented small-signal step according to claim 1, characterized in that, the system further includes an analog quantity output board card, a digital quantity output board card, and a digital quantity input board card. The analog quantity output board card is respectively connected to the simulation platform and the small-signal superposition and holding module. The digital quantity output board card and the digital quantity input board card are respectively connected to the simulation platform and the hardware device of the wind turbine converter controller, where: The analog output board card outputs the grid-side three-phase voltage and / or current, DC bus voltage, machine-side three-phase voltage and / or current, and high-frequency speed encoder pulse signal of the doubly-fed wind turbine grid-connected operation model to the small-signal superposition and holding module; The digital output board card outputs the opening and closing status quantities of the stator-side grid-connected switch and the grid-side converter grid-connected switch to the wind turbine converter controller hardware device; The digital input board card inputs the converter high-frequency pulse trigger signal and switch control signal into the doubly-fed wind turbine grid-connected operation model.

4. The doubly-fed wind turbine converter parameter test system based on sub-link small-signal step as claimed in claim 1, characterized in that, The upper computer controls the input analog quantity to enter the direct-through quantity channel, step channel, power holding channel or signal holding channel according to the simulation requirements.

5. The doubly-fed wind turbine converter parameter test system based on sub-link small-signal step as claimed in claim 4, characterized in that, The step channel includes a first signal decomposition sub-module, a small-signal step sub-module and a signal synthesis sub-module, and the first signal decomposition sub-module, the small-signal step sub-module and the signal synthesis sub-module are connected in sequence, where: The first signal decomposition sub-module is used to perform Fourier decomposition on the input analog quantity signal to obtain the amplitude and phase of each frequency point; The small-signal step sub-module is used to perform an up-step or down-step of the amplitude of A% on the analog quantity signal at the moment T0 according to the step amplitude A%, step moment T0 and step direction set by the upper computer; The signal synthesis sub-module is used to superimpose and synthesize signals of different frequencies and then output.

6. The doubly-fed wind turbine converter parameter test system based on sub-link small-signal step as claimed in claim 1, characterized in that, The identification test of the control parameters of the doubly-fed wind turbine converter includes the identification of the d-axis current inner loop parameters of the grid-side converter and the identification of the DC voltage outer loop parameters.

7. The doubly-fed wind turbine converter parameter test system based on sub-link small-signal step as claimed in claim 6, characterized in that, When the identification test of the control parameters of the doubly-fed wind turbine converter is the identification of the d-axis current inner loop parameters of the grid-side converter, the implementation process is as follows: The upper computer switches the DC voltage analog quantity in the small-signal superposition and holding module from the direct-through quantity to the signal holding quantity, switches the grid-side converter sampled three-phase AC current analog quantity from the direct-through quantity to the quantity to be stepped, sets the step amplitude to A%, and A≤10, the step frequency is 50Hz, and the step direction is up or down step; At the moment T0, the upper computer realizes the signal holding of the DC voltage analog quantity and the step of the grid-side converter sampled three-phase AC current analog quantity in the set step direction, and records the step waveform of the grid-side converter sampled three-phase AC current analog quantity; Based on the grid-side power supply phase angle, the DQ decomposition is performed on the grid-side converter sampled three-phase AC current analog quantity to obtain the step waveforms of the d-axis and q-axis currents in its DQ coordinates. Based on the rise time, adjustment time, peak time and overshoot of the step waveforms of the d-axis and q-axis currents, the d-axis current inner loop proportional coefficient kp and integral coefficient ki are identified.

8. The double-fed wind turbine converter parameter testing system based on sub-link small-signal step as claimed in claim 6, characterized in that, when the identification test of the double-fed wind turbine converter control parameter is the identification of the DC voltage outer loop parameter, the implementation process is as follows: Through the host computer, the three-phase AC current analog quantity sampled by the grid-side converter in the small-signal superposition and hold module is switched from the required step quantity to the through quantity, and the DC voltage analog quantity is switched from the signal hold quantity to the required step quantity. At the same time, the step amplitude is set to B%, where B ≤ 10, and it is necessary to ensure that the DC voltage amplitude after the step does not meet the starting condition of the DC bus CHOPPER circuit, the step frequency is 0 Hz, and the step direction is up or down step; At time T0, the host computer is used to step the DC voltage analog signal in the set step direction, record the DC voltage step waveform, and identify the proportional coefficient kp and integral coefficient ki of the DC voltage outer loop based on the rise time, adjustment time, peak time, and overshoot of the DC voltage step waveform.

9. The double-fed wind turbine converter parameter testing system based on sub-link small-signal step as claimed in claim 5, characterized in that, The power holding channel includes a second signal decomposition sub-module, a first signal holding sub-module, and a power holding sub-module. The first signal holding sub-module is respectively connected to the second signal decomposition sub-module and the power holding sub-module. The power holding sub-module is also connected to the small-signal step sub-module, where: The second signal decomposition sub-module is used to perform Fourier decomposition on the input analog signal to obtain the amplitude and phase of each frequency point; The first signal holding sub-module is used to store, save, and synthesize the amplitude and phase of each frequency point output by the second signal decomposition sub-module according to the command signal of the host computer, so that the output signal currently passing through the first signal holding sub-module is the same as the analog input signal input to the small-signal superposition and hold module at time T0; The power holding sub-module is used to keep the power value of the input analog signal passing through the power holding channel unchanged, and to keep the corresponding power value unchanged after the required step analog signal performs a small-signal step.

10. The double-fed wind turbine converter parameter testing system based on sub-link small-signal step as claimed in claim 1, characterized in that, The signal holding channel includes a third signal decomposition sub-module and a second signal holding sub-module. The third signal decomposition sub-module is connected to the second signal holding sub-module, where: The third signal decomposition sub-module is used to perform Fourier decomposition on the input analog signal to obtain the amplitude and phase of each frequency point; The second signal holding sub-module is used to store, save, and synthesize the amplitude and phase of each frequency point output by the third signal decomposition sub-module according to the command signal of the host computer, so that the output signal currently passing through the second signal holding sub-module is the same as the analog input signal input to the small-signal superposition and hold module at time T0.

11. The double-fed wind turbine converter parameter testing system based on the step-by-step small-signal step as described in any one of claims 1-10, characterized in that, the simulation platform is a real-time digital simulation system RTDS platform.

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