Variable speed pumped storage unit self-starting control method and variable speed pumped storage unit

Abstract

This application relates to a self-starting control method for a variable-speed pumped-storage unit and the variable-speed pumped-storage unit itself. The self-starting control method, when the stator is not connected to the grid, controls each power branch to pre-charge to establish the DC bus voltage; connects a portion of the power branches to the rotor and another portion to the stator; based on the rotor position relative to the stator, modulates the excitation current of each power branch to drive the rotor to smoothly increase speed; when the rotor reaches a preset speed, the power branches are connected to the rotor. The self-starting control method for a variable-speed pumped-storage unit provided in this application, by omitting the SFC (Self-Fuel Collector) and reusing the advantages of a multi-branch parallel converter topology, achieves SFC-less starting, solving the problems of high cost, low utilization, and complex excitation systems caused by the requirement of a separate SFC for traditional pumped-storage units. This simplifies the system structure, reduces costs, and improves operational reliability.

Description

Technical Field

[0001] This application belongs to the field of motor control technology, and in particular relates to a method for self-starting control of a variable speed pumped storage unit, a variable speed pumped storage unit, and a computer program product. Background Technology

[0002] The core of a variable-speed pumped-storage unit is an AC-excited doubly-fed motor. The stator windings are directly connected to the power grid, while the rotor windings are connected to an AC excitation converter. By adjusting the frequency, amplitude, and phase of the rotor excitation, the unit speed can be continuously adjusted within ±10% of the synchronous speed (typical industry range), perfectly adapting to the operational requirements of grid frequency regulation, peak shaving, and head fluctuations. The doubly-fed motor rotor of the variable-speed pumped-storage unit has an excitation pole structure. In a static state, the stator cannot generate a constant average torque when energized at the power frequency, resulting in an inherent defect that it cannot start on its own. Furthermore, the unit typically has a large moment of inertia and high starting resistance under load. In pumped-storage electric operation, a static frequency converter (SFC) must be used to drive the unit from zero speed to synchronous speed.

[0003] In the electric operation of pumped-storage units, voltage-source converters are generally considered to be constant-voltage controlled. At low frequencies, the stator impedance is low and the induced electromotive force is low, making the stator current prone to runaway. Therefore, the industry generally accepts that voltage-source converters cannot replace current-source static frequency converters, solidifying the traditional design approach of AC excitation converter plus independent SFC. In the AC excitation converter plus independent SFC architecture, the converter uses fully controlled power devices, such as integrated gate-commutated thyristors (IGCTs) and insulated-gate bipolar transistors (IGBTs), in a voltage-source topology to provide DC excitation to the rotor. The SFC is a current-source thyristor converter that connects to the stator winding to output a 0~50Hz frequency conversion current, working in conjunction with the excitation system to limit inrush current and achieve unit startup. However, separate configuration of SFC cabinets, isolation transformers, smoothing reactors, and dedicated control cabinets is required, significantly increasing the supporting facilities and land area, resulting in higher equipment costs. Furthermore, the SFC equipment remains idle after startup, leading to short commissioning time and low utilization. Moreover, the converter and SFC are typically coordinated by different controllers, requiring multi-port collaborative communication, making the control system complex and maintenance difficult. Summary of the Invention

[0004] The purpose of this application is to provide a method for automatic start-up control of a variable speed pumped-storage unit, as well as a variable speed pumped-storage unit and a computer program product, in order to solve the problems of high cost, low utilization rate and complex control of the AC excitation converter plus independent SFC architecture in the automatic start-up of variable speed pumped-storage units.

[0005] In a first aspect, embodiments of this application provide an automatic start-up control method for a variable-speed pumped-storage unit. The variable-speed pumped-storage unit includes a rotor, a stator, and M power branches. The stator is used for connection to the power grid, the input terminals of each power branch are respectively used for connection to the power grid, and the output terminals of each power branch are respectively used for connection to the rotor and the stator. The control method includes: When the stator is not connected to the grid, each of the power branches is pre-charged to establish the DC bus voltage; A portion of all the power branches are connected to the rotor, and another portion of the power branches are connected to the stator, wherein the sum of the number of power branches connected to the rotor and the number of power branches connected to the stator is less than or equal to M; Based on the rotor position relative to the stator, the excitation current of each power branch is modulated to drive the rotor to accelerate smoothly. When the rotor reaches the preset speed, N power branches are connected to the rotor and the stator is connected to the grid, where N is less than or equal to M.

[0006] In one embodiment, modulating the excitation current of each of the power branches to drive the rotor to smoothly accelerate includes: The power branch connected to the rotor is controlled to output a constant DC excitation current to establish a constant rotor magnetic pole magnetic field. The power branch connected to the stator is controlled to output AC power of a preset frequency and preset voltage to establish a zero-speed constant torque; The power branch connected to the stator is controlled to gradually increase the frequency and voltage of the AC power according to a preset speed-up curve, so as to drive the rotor to speed up smoothly.

[0007] In one embodiment, during the process of gradually increasing the frequency and voltage of the alternating current according to a preset acceleration curve, the DC excitation current and the current of the alternating current are finely adjusted to suppress torque pulsation.

[0008] In one embodiment, the preset frequency is 0~50Hz.

[0009] In one embodiment, the power branch includes a grid-side filter capacitor, a first power converter, a second power converter, a DC bus capacitor, a machine-side filter capacitor, and a soft-start circuit. The grid-side filter capacitor, the first power converter, the second power converter, and the machine-side filter capacitor are connected sequentially. The DC bus capacitor is connected to the DC bus between the first power converter and the second power converter. The soft-start circuit is connected between the power grid and the DC bus. Controlling each of the power branches to pre-charge and establish the DC bus voltage includes: The soft-start circuit is controlled to charge the DC bus capacitor to a first preset voltage. The first power converter of one of the power branches is controlled to charge the grid-side filter capacitors of all the power branches to a second preset voltage; Control all of the aforementioned power branches to connect to the grid.

[0010] In one embodiment, prior to connecting the stator to the grid, the method further includes: The excitation voltage of the stator is modulated to match the power grid.

[0011] In one embodiment, after the stator is connected to the grid, the method further includes: Control the variable speed pumped storage unit to enter steady-state electric mode.

[0012] In one embodiment, the preset speed is the speed at which the variable-speed pumped-storage unit operates in steady state under the drive of the grid voltage.

[0013] Secondly, embodiments of this application also provide a variable-speed pumped-storage unit, including a rotor, a stator, M power branches, a memory, a processor, and a computer program stored in the memory and executable on the processor. The stator is used to connect to the power grid, the input terminals of each power branch are respectively used to connect to the power grid, the output terminals of each power branch are respectively used to connect the rotor and the stator, the processor is connected to each power branch, and when the processor executes the computer program, it implements the steps of the variable-speed pumped-storage unit self-starting control method described above.

[0014] Thirdly, embodiments of this application also provide a computer program product that, when run on a computer, causes the computer to execute the variable-speed pumped storage unit self-start control method as described above.

[0015] The beneficial effects of this application's embodiments compared to related technologies are as follows: The variable-speed pumped-storage unit self-starting control method provided in this application, when the stator is not connected to the grid, controls each power branch to pre-charge to establish the DC bus voltage; connects a portion of the power branches to the rotor and another portion to the stator; based on the rotor position relative to the stator, modulates the excitation current of each power branch to drive the rotor to smoothly increase speed; when the rotor reaches the preset speed, connects the power branches to the rotor. The variable-speed pumped-storage unit self-starting control method provided in this application, by omitting the SFC (Self-Fuel Concentrator), reuses the advantages of multi-branch parallel converter topology to achieve SFC-free starting, solving the problems of high cost, low utilization, and complex excitation system caused by the requirement of an independent SFC for traditional pumped-storage unit starting. This simplifies the system structure, reduces costs, and improves operational reliability. Attached Figure Description

[0016] Figure 1 This is a circuit diagram of a variable-speed pumped storage unit provided in an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of the power branch in a variable-speed pumped-storage unit provided in an embodiment of this application.

[0018] Figure 3 A flowchart of a variable-speed pumped-storage unit self-starting control method provided in an embodiment of this application.

[0019] Figure 4 A flowchart of a variable-speed pumped-storage unit self-starting control method provided in another embodiment of this application.

[0020] Figure 5 This is a schematic diagram of a module of a variable-speed pumped storage unit self-starting control device provided in an embodiment of this application.

[0021] Figure 6 This is a schematic diagram of a variable-speed pumped storage unit provided in an embodiment of this application. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0023] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0024] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0026] like Figure 1 As shown, this application describes a variable-speed pumped-storage unit with a multi-branch parallel converter in one embodiment. The variable-speed pumped-storage unit includes a control and protection unit 101, a rotor 102, a stator 103, a first grid-connected switch 104, a second grid-connected switch 105, M rotor excitation switches 106, M excitation transformers 107, M stator excitation switches 108, and M power branches 110, where M ≥ 2. The stator 103 is connected to the power grid 200 via the first grid-connected switch 104. The input terminals of the M power branches 110 are respectively connected to the secondary side of the M excitation transformers 107. The primary side of the M excitation transformers 107 is connected to the power grid 200 via the second grid-connected switch 105. The output terminal of one power branch 110 is connected to the rotor 102 via a rotor excitation switch 106, and the output terminal of one power branch 110 is connected to the stator 103 via a stator excitation switch 108.

[0027] It is understandable that the M power branches 110 can be multiple converters or integrated into one converter. At any given time, one of the rotor excitation switch 106 and stator excitation switch 108 connected to the output terminal of one power branch 110 is turned on, while the other is turned off.

[0028] like Figure 2 As shown, in one embodiment, the power branch 110 includes a grid-side filter circuit 111, a first power converter 112, a second power converter 113, a DC bus capacitor C0, a machine-side filter circuit 114, and a soft-start circuit 115. The grid-side filter circuit 111, the first power converter 112, the second power converter 113, and the machine-side filter circuit 114 are sequentially connected between the input and output terminals of the power branch 110. The DC bus capacitor C0 is connected to the DC bus between the first power converter 112 and the second power converter 113. The soft-start circuit 115 is connected between the power grid 200 and the DC bus.

[0029] The grid-side filter circuit 111 includes a grid-side filter capacitor C1 and a grid-side filter inductor L1. The generator-side filter circuit 114 includes a generator-side filter capacitor C2 and a generator-side filter inductor L2. Both the first power converter 112 and the second power converter 113 are bidirectional AC / DC power converters. During the startup phase of the variable-speed pumped-storage unit, the first power converter 112 can operate in inverter mode. During the steady-state phase of the variable-speed pumped-storage unit, the first power converter 112 operates in rectification mode, and the second power converter 113 operates in inverter mode. The soft-start circuit 115 directly draws power from the grid 200, i.e., Vac.

[0030] In one embodiment, the soft-start circuit 115 includes a soft-start switch K1, a pre-charge resistor R1, a pre-charge transformer T1, and a rectifier D1, which are connected in series between the DC bus of the power grid 200.

[0031] like Figure 3 As shown, one embodiment of this application provides an automatic start-up control method for a variable-speed pumped-storage unit, combined with... Figures 1 to 3 The control methods include: In step S110, when the stator 103 is not connected to the grid, each power branch 110 is controlled to precharge in order to establish the DC bus voltage.

[0032] Each power branch 110 independently charges its DC bus capacitor C0 through its respective soft-start module. Each power branch 110 initiates a pre-charging process according to a preset timing sequence to establish the DC bus voltage and thereby establish the input voltage synchronized with the power grid 200.

[0033] In step S120, a portion of the power branches 110 are connected to the rotor 102, and another portion of the power branches 110 are connected to the stator 103. The sum of the number of power branches 110 connected to the rotor 102 and the number of power branches 110 connected to the stator 103 is less than or equal to M.

[0034] The power branch 110 connected to the rotor 102 via the rotor excitation switch 106 can be defined as the rotor 102 excitation branch, and the power branch 110 connected to the stator 103 via the stator excitation switch 108 can be defined as the stator 103 excitation branch. It is understood that during startup, depending on the power requirements or application scenario of the variable-speed pumped-storage unit, it is not necessary to use all of the power branch 110 for excitation of the rotor 102 and stator 103. Therefore, depending on the power requirements or application scenario, some or all of the power branch 110 can be used for excitation of the rotor 102 and stator 103.

[0035] In step S130, based on the rotor position of rotor 102 relative to stator 103, the excitation current of each power branch 110 is modulated to drive rotor 102 to accelerate smoothly.

[0036] The rotor 102 excitation branch outputs a constant DC excitation current to establish a constant magnetic field of the rotor 102 poles; the stator 103 excitation branch outputs a low-frequency, low-voltage AC current to achieve zero-speed constant torque establishment.

[0037] Before startup, based on the rotor position of rotor 102 relative to stator 103, the output frequency and voltage of the excitation branch of stator 103 are gradually increased according to the preset speed-up curve to maintain magnetic flux stability; the excitation current is finely adjusted to suppress torque pulsation, and the excitation current of stator 103 is limited to overcurrent through closed-loop control to overcome large inertia and load resistance, so as to achieve stable speed-up of the unit.

[0038] In step S140, when the rotor 102 reaches the preset speed, N power branches 110 are connected to the rotor 102 and the stator 103 is connected to the grid, wherein N is less than or equal to M.

[0039] It is understandable that, depending on the power or application scenario requirements of the variable speed pumped storage unit, it is not necessary to use all power branches 110 for rotor 102 excitation for grid connection and operation. Therefore, some or all of the power branches 110 can be used for rotor 102 excitation according to the power or application scenario requirements.

[0040] The technical solution of this application embodiment ensures the establishment of DC bus voltage for each branch by soft-starting and grid connection of multiple power branches 110. Based on the excitation requirements of rotor 102 and stator 103, the power branches 110 are divided into rotor 102 excitation branches and stator 103 excitation branches. Through control strategies, fully controllable devices in the power branches 110, and optimized topology, DC excitation is provided to rotor 102, and AC excitation is provided to stator 103, achieving stable unit speed-up. Finally, the stator 103 excitation branch is completely switched to the rotor 102 excitation branch, stator 103 is connected to the grid, and the unit enters steady-state mode. By omitting the SFC (Self-Fuel Converter), the advantages of the multi-branch parallel converter topology are reused to achieve SFC-free starting and grid connection. This solves the problems of high cost, low utilization, and complex excitation systems caused by the requirement of independent SFCs for traditional pumped-storage units during startup, simplifying the system structure, reducing costs, and improving operational reliability.

[0041] In one embodiment, before step S110, the control and protection unit 101 is powered on and the system status such as multiple power branches 110, DC bus voltage, motor winding resistance and insulation is detected. After confirming that everything is normal, the process proceeds to step S110.

[0042] like Figure 4As shown, in one embodiment, the modulation of the excitation current of each power branch 110 in step S130 to drive the rotor 102 to smoothly accelerate includes: Step S131: Control the power branch 110 connected to the rotor 102 to output a constant DC excitation current, and establish a constant magnetic field of the rotor 102.

[0043] In step S132, the power branch 110 connected to the stator 103 is controlled to output AC power with a preset frequency and preset voltage to establish a zero-speed constant torque.

[0044] In step S133, the power branch 110 connected to the stator 103 is controlled to gradually increase the frequency and voltage of the AC power according to the preset speed-up curve, so as to drive the rotor 102 to speed up smoothly.

[0045] In step S131, the corresponding circuit is switched on. In step S132, the preset frequency of the AC power is 0~50Hz. In step S133, the upper limit of the AC power frequency is increased to 50Hz to maintain magnetic flux stability.

[0046] In one embodiment, as the frequency and voltage of the AC power are gradually increased according to a preset acceleration curve, the DC excitation current and the AC current are finely adjusted to suppress torque pulsation. Furthermore, the stator 103 excitation current is limited by closed-loop control to overcome large inertia and load resistance, achieving stable unit acceleration.

[0047] In one embodiment, step S110 involves controlling each power branch 110 to pre-charge to establish a DC bus voltage, including: Step A: Control the soft-start circuit 115 to charge the DC bus capacitor C0 to the first preset voltage.

[0048] Each power branch 110's soft-start circuit 115 draws power from the grid 200 to precharge its DC bus capacitor C0. The first preset voltage is usually 80%-100% of the rated DC bus voltage.

[0049] Step B involves controlling the first power converter 112 of one power branch 110 to charge the grid-side filter capacitor C1 of all power branches 110 to the second preset voltage.

[0050] In one example, the DC bus capacitor C0 of the first power branch 110 is used as the power source. The first power converter 112 of the first power branch 110 is controlled to operate in inverter mode, and the output charging current charges the grid-side filter capacitors C1 of each power branch 110 to a second preset voltage through each excitation transformer 107. During this charging process, the first power converter 112 of the first power branch 110 is used to generate a phase-locked loop (PLL) signal with reference to the phase, frequency, and amplitude of the grid voltage (i.e., the grid voltage) or the secondary rated voltage of the excitation transformer 107. The first power converter 112 outputs a charging signal to synchronously charge each grid-side filter capacitor C1, charging each grid-side filter capacitor C1 to the second preset voltage. The amplitude of the second preset voltage is 80% to 100% of the grid voltage or the secondary rated voltage of the excitation transformer 107. The phase and frequency of each grid-side filter capacitor C1 are in phase with the grid voltage or the rated voltage of the secondary side of the excitation transformer 107, so as to enable the second grid-connected switch 105 to perform impact-free grid connection.

[0051] Step C: Control all power branches 110 to connect to the grid. That is, control the second grid connection switch 105 to turn on.

[0052] In one embodiment, in step B, the soft-start circuit in the first power branch 110 is controlled to maintain the charging of the DC bus capacitor of the first power branch 110, while the soft-start circuits in other power branches besides the first power branch 110 are controlled to be turned off. This reduces the energy loss and voltage drop of the DC bus capacitor C0 of the first power branch 110 during the charging process of the grid-side filter capacitor C1 in each power branch 110, thereby reducing the inrush current during grid connection.

[0053] In one embodiment, prior to connecting the stator 103 to the grid in step S140, the method further includes: The excitation voltage of stator 103 is adjusted to match the power grid, and the first grid connection switch 104 is turned on, so that stator 103 is connected to the grid. The AC excitation control module in the control and protection unit 101 adjusts the frequency, phase and amplitude of the excitation voltage of stator 103 to match the power grid 200, so as to achieve shock-free grid connection of stator 103.

[0054] In one embodiment, after connecting the stator 103 to the grid in step S140, the method further includes: controlling the variable speed pumped storage unit to enter steady-state electric mode, so as to achieve seamless switching between excitation start-up and grid-connected operation.

[0055] In one embodiment, the preset speed is the steady-state speed of the variable-speed pumped-storage unit when it is connected to the grid and driven by the grid voltage.

[0056] like Figure 5As shown, one embodiment of this application also provides an automatic start control device for a variable speed pumped-storage unit, the control device comprising: The soft-start module 510 is used to control each of the power branches to precharge in order to establish the DC bus voltage when the stator is not connected to the grid. The switch control module 520 is used to connect a portion of the power branches to the rotor and another portion of the power branches to the stator, wherein the sum of the number of power branches connected to the rotor and the number of power branches connected to the stator is less than or equal to M. The modulation module 530 is used to modulate the excitation current of each of the power branches to drive the rotor to accelerate smoothly based on the rotor position relative to the stator. The switch control module 520 is also used to connect N power branches to the rotor and connect the stator to the grid when the rotor reaches the preset speed, wherein N is less than or equal to M.

[0057] In one embodiment, the modulation module 530 includes: The rotor modulation module is used to control the power branch connected to the rotor to output a constant DC excitation current and establish a constant rotor magnetic pole magnetic field. The stator modulation module is used to control the power branch connected to the stator to output AC power with a preset frequency and preset voltage to establish a zero-speed constant torque; it is also used to control the power branch connected to the stator to gradually increase the frequency and voltage of the AC power according to a preset acceleration curve to drive the rotor to accelerate smoothly.

[0058] In one embodiment, the rotor modulation module and the stator modulation module are also used to fine-tune the DC excitation current and the AC current to suppress torque pulsation.

[0059] In one embodiment, the soft-start module 510 is specifically used for: The soft-start circuit is controlled to charge the DC bus capacitor to a first preset voltage. The first power converter of one of the power branches is controlled to charge the grid-side filter capacitors of all the power branches to a second preset voltage; Control all of the aforementioned power branches to connect to the grid.

[0060] In one embodiment, the switch control module 520 is further configured to control the stator to connect to the grid after adjusting the stator's excitation voltage to match the grid.

[0061] In one embodiment, the modulation module 530 is also used to control the variable-speed pumped-storage unit to enter a steady-state electric mode.

[0062] For details on the specific implementation methods and related beneficial effects of the variable-speed pumped-storage unit self-starting control device in this application, please refer to the description of the specific implementation methods of the variable-speed pumped-storage unit self-starting control method described above, which will not be repeated here.

[0063] Combination Figure 1 , Figure 2 and Figure 6 As shown, in a second aspect, embodiments of this application also provide a variable-speed pumped-storage unit, including a rotor 102, a stator 103, M power branches 110, a memory 120, a processor, and a computer program 121 stored in the memory 120 and executable on the processor. The stator 103 is used to connect to the power grid 200, the input terminals of each power branch 110 are respectively used to connect to the power grid 200, the input terminals of each power branch 110 are respectively used to connect the rotor 102 and the stator 103, the processor is connected to each power branch 110, and when the processor executes the computer program 121, it implements the steps of the above-mentioned variable-speed pumped-storage unit self-starting control method.

[0064] It is understood that the processor is the aforementioned control and protection unit 101, or a part thereof. Those skilled in the art will understand that... Figure 6 This is merely an example of a variable-speed pumped-storage unit and does not constitute a limitation on variable-speed pumped-storage units. It may include more or fewer components than shown in the figure, or combine certain components, or different components, such as input / output devices, network access devices, etc.

[0065] The processor can be a Central Processing Unit (CPU), or it can be other general-purpose controllers, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose controller can be a microcontroller or any conventional controller.

[0066] In some embodiments, memory 120 may be an internal storage unit of the variable-speed pumped-storage unit, such as the hard drive or RAM of the variable-speed pumped-storage unit. In other embodiments, memory 120 may be an external storage device of the variable-speed pumped-storage unit, such as a plug-in hard drive, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the variable-speed pumped-storage unit. Furthermore, memory 120 may include both internal storage units and external storage devices of the variable-speed pumped-storage unit. Memory 120 is used to store the operating system, applications, boot loader, data, and other programs. Memory 120 may also be used to temporarily store data that has been output or will be output.

[0067] This application also provides a computer-readable storage medium storing a computer program 121, which, when executed by a processor, can implement the steps in the above-described method embodiments.

[0068] This application provides a computer program product that, when run on a computer, causes the computer to perform the steps described in the various method embodiments above.

[0069] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above method embodiments of this application can be implemented by a computer program 121 instructing related hardware. The computer program 121 can be stored in a computer-readable storage medium. When the computer program 121 is executed by a processor, it can implement the steps of the various method embodiments described above. The computer program 121 includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a photographing device / terminal device, recording media, computer memory, ROM (Read-Only Memory), RAM (Random Access Memory), CD-ROM (Compact Disc Read-Only Memory), magnetic tape, floppy disk, and optical data storage devices. The computer-readable storage medium mentioned in this application can be a non-volatile storage medium; in other words, it can be a non-transient storage medium.

[0070] It should be understood that all or part of the steps of the above embodiments can be implemented by software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented in whole or in part as a computer program product. The computer program product includes one or more computer instructions. The computer instructions can be stored in the above-described computer-readable storage medium.

[0071] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0072] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0073] In the embodiments provided in this application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0074] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0075] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for self-starting control of a variable-speed pumped-storage unit, characterized in that, The variable-speed pumped-storage unit includes a rotor, a stator, and M power branches. The stator is used to connect to the power grid, the input terminals of each power branch are used to connect to the power grid, and the output terminals of each power branch are used to connect the rotor and the stator. The control method includes: When the stator is not connected to the grid, each of the power branches is pre-charged to establish the DC bus voltage; A portion of all the power branches are connected to the rotor, and another portion of the power branches are connected to the stator, wherein the sum of the number of power branches connected to the rotor and the number of power branches connected to the stator is less than or equal to M; Based on the rotor position relative to the stator, the excitation current of each power branch is modulated to drive the rotor to accelerate smoothly. When the rotor reaches the preset speed, N power branches are connected to the rotor and the stator is connected to the grid, where N is less than or equal to M.

2. The control method as described in claim 1, characterized in that, The modulation of the excitation current of each of the power branches to drive the rotor to smoothly increase speed includes: The power branch connected to the rotor is controlled to output a constant DC excitation current to establish a constant rotor magnetic pole magnetic field. The power branch connected to the stator is controlled to output AC power of a preset frequency and preset voltage to establish a zero-speed constant torque; The power branch connected to the stator is controlled to gradually increase the frequency and voltage of the AC power according to a preset speed-up curve, so as to drive the rotor to speed up smoothly.

3. The control method as described in claim 2, characterized in that, During the process of gradually increasing the frequency and voltage of the AC power according to the preset acceleration curve, the DC excitation current and the AC current are finely adjusted to suppress torque pulsation.

4. The control method as described in claim 2, characterized in that, The preset frequency is 0~50Hz.

5. The control method according to any one of claims 1 to 4, characterized in that, The power branch includes a grid-side filter capacitor, a first power converter, a second power converter, a DC bus capacitor, a machine-side filter capacitor, and a soft-start circuit. The grid-side filter capacitor, the first power converter, the second power converter, and the machine-side filter capacitor are connected sequentially. The DC bus capacitor is connected to the DC bus between the first power converter and the second power converter. The soft-start circuit is connected between the power grid and the DC bus. Controlling each power branch to pre-charge and establish the DC bus voltage includes: The soft-start circuit is controlled to charge the DC bus capacitor to a first preset voltage. The first power converter of one of the power branches is controlled to charge the grid-side filter capacitors of all the power branches to a second preset voltage; Control all of the aforementioned power branches to connect to the grid.

6. The control method according to any one of claims 1 to 4, characterized in that, Before connecting the stator to the grid, the process also includes: The excitation voltage of the stator is modulated to match the power grid.

7. The control method according to any one of claims 1 to 4, characterized in that, After connecting the stator to the grid, the following is also included: Control the variable speed pumped storage unit to enter steady-state electric mode.

8. The control method according to any one of claims 1 to 4, characterized in that, The preset speed is the speed at which the variable-speed pumped-storage unit operates in a steady state under the drive of the grid voltage.

9. A variable-speed pumped-storage unit, characterized in that, The system includes a rotor, a stator, M power branches, a memory, a processor, and a computer program stored in the memory and executable on the processor. The stator is used to connect to the power grid, the input terminals of each power branch are used to connect to the power grid, the output terminals of each power branch are used to connect the rotor and the stator, the processor is connected to each power branch, and when the processor executes the computer program, it implements the steps of the automatic start-up control method for the variable speed pumped storage unit as described in any one of claims 1 to 8.

10. A computer program product, characterized in that, When it is run on a computer, it causes the computer to execute the automatic start control method for variable speed pumped storage units as described in any one of claims 1 to 8.

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