Variable-speed pumped storage unit starting method and device and power equipment

Abstract

The invention relates to a motor control technology, and provides a variable-speed pumped storage unit starting method and device and power equipment, which utilize an excitation converter to short-circuit a unit rotor according to a preset strategy, avoid out-of-step of the unit caused by too fast acceleration during back-to-back starting or SFC starting, increase the starting success rate and improve the starting efficiency. Moreover, the excitation converter in the system is reused to realize short circuit of the rotor of the unit, so that the cost is saved, and the excitation converter can be used for actively limiting the current of the rotor.

Description

Technical Field

[0001] The present application belongs to the field of motor control technology, and in particular relates to a variable speed pumped storage unit starting method, device and power equipment. Background Art

[0002] Since the water head of a pumped storage power station changes greatly during operation, it directly affects the speed corresponding to the optimal efficiency of power generation. Conventional units have a small speed regulation range and cannot meet the requirements of the turbine operating at the optimal speed at all times. The variable speed unit can adjust the motor speed within a certain range to adapt to wider water head changes, improve the operating efficiency of the turbine, and improve the hydraulic performance of the turbine.

[0003] Pumped storage units are started and stopped many times every day, and the starting problem plays a very important role in the daily operation of the unit. Generally, variable-speed pumped storage units use doubly fed induction generators (DFIGs), which can be started by a speed governor in power generation conditions, but the pumping conditions require the unit to start automatically. The current self-starting method is to short-circuit the stator of the doubly fed unit, connect the excitation converter to the rotor of the doubly fed unit, let it work in the asynchronous motor mode, start the unit to speed up to the grid-connected speed, and then disconnect the short-circuit breaker on the stator side. Then the excitation converter switches back to the doubly fed motor mode, AC excitation is given to the doubly fed unit, and the stator side main circuit breaker is opened after the stator voltage is synchronized with the grid voltage. At this point, the doubly fed unit is connected to the grid. However, for large-power doubly-fed units, due to the influence of leakage inductance and the limitation of the output voltage capacity of the excitation converter, the speed cannot be increased to the grid-connected speed. At this time, the doubly-fed unit needs to be started back-to-back or by a static frequency changer (SFC).

[0004] Back-to-back starting is a backup starting method for pumped storage units. A conventional / variable speed unit of the power station or an adjacent power station is used to start the doubly fed unit. The stators of the conventional / variable speed unit and the doubly fed unit are electrically connected to each other through the starting bus, and the rotor is added with DC / AC and DC excitation. The conventional / variable speed unit uses the water flow to impact the turbine to rotate and generate low-frequency current, which is applied to the stator of the doubly fed unit through the starting bus to drive the doubly fed unit to rotate. As the opening of the turbine guide vane increases, the speed of the conventional unit slowly increases, and the speed of the doubly fed unit also increases synchronously. SFC starting uses the frequency converter to generate variable frequency AC power to drive the doubly fed unit. The stator of the doubly fed unit is connected to the output side of the SFC through the starting bus, and the rotor is added with DC excitation.

[0005] Whether it is back-to-back starting or SFC starting, there will be a problem, that is, the speed cannot increase too fast, otherwise it will cause the rotor to lose step. Summary of the invention

[0006] The purpose of the present application is to provide a variable-speed pumped-storage unit starting method, device and power equipment, aiming to solve the problem that the variable-speed pumped-storage unit is prone to losing step during rapid starting under pumping conditions.

[0007] In a first aspect, an embodiment of the present application provides a variable speed pumped storage unit starting method, comprising: In response to the unit pumping start command, the excitation converter is controlled to short-circuit the unit rotor according to a preset strategy; Turn on the drive power supply device to drive the stator of the unit to increase the speed of the unit to the grid-connected speed.

[0008] In one embodiment, before controlling the excitation converter to short-circuit the unit rotor according to a preset strategy, the method further includes: detecting operating parameters of the unit; When the operating parameter is less than the corresponding parameter threshold, the excitation converter is controlled to short-circuit the unit rotor according to a preset strategy.

[0009] In one embodiment, after the driving power supply device is turned on to drive the stator of the unit, the method further includes: When the operating parameter is greater than or equal to the corresponding parameter threshold, the excitation converter is controlled to stop short-circuiting the unit rotor.

[0010] In one of the embodiments, the detected operating parameters of the unit include at least one of the rotor current, motor temperature, excitation converter temperature, and excitation converter overload rate of the unit.

[0011] In one embodiment, the excitation converter includes a two-level converter, and controlling the excitation converter to short-circuit the unit rotor according to a preset strategy includes: Before the unit speed increases to the grid-connected speed, the two-level converter is controlled to alternate between the following two states or maintain any one of the states: The three-phase upper bridge arm switch tubes are synchronously normally turned on, and the three-phase lower bridge arm switch tubes are synchronously normally turned off; The three-phase upper bridge arm switch tubes are synchronously normally turned off, and the three-phase lower bridge arm switch tubes are synchronously normally turned on.

[0012] In one embodiment, the excitation converter includes a type I NPC three-level converter or a type II NPC three-level converter, and the control of the excitation converter to short-circuit the unit rotor according to a preset strategy includes: Before the unit speed increases to the grid-connected speed, in each switching cycle, the type I NPC three-level converter or the type II NPC three-level converter is controlled to alternate between the following three states or to maintain in any one of the states: The switch tubes of the three-phase upper bridge arm are turned on synchronously, and the switch tubes of the three-phase lower bridge arm are turned off synchronously; The switch tubes of the three-phase lower bridge arm are turned on synchronously, and the switch tubes of the three-phase upper bridge arm are turned off synchronously; Only the three-phase zero-level paths are turned on synchronously.

[0013] In one embodiment, the excitation converter comprises an ANPC three-level converter, and the ANPC three-level converter comprises three-phase bridge arms, and each phase bridge arm comprises: A first upper switch tube and a second upper switch tube connected in series between the bus midpoint and the bus positive electrode; A first lower switch tube and a second lower switch tube connected in series between the negative electrode of the busbar and the midpoint of the busbar; A third upper switch tube, the third upper switch tube being connected between a series connection point between the first upper switch tube and the second upper switch tube and a midpoint of the busbar; and A third lower switch tube, the third lower switch tube being connected between a series connection point between the first lower switch tube and the second lower switch tube and a midpoint of the busbar; The controlling the excitation converter to short-circuit the unit rotor according to a preset strategy includes: Before the unit speed increases to the grid-connected speed, in each switching cycle, the ANPC three-level converter is controlled to alternate between the following six states or to maintain any one of the states: The first upper switch tube and the second upper switch tube of each phase bridge arm are synchronously turned on, and the third upper switch tube, the first lower switch tube, the second lower switch tube, and the third lower switch tube of each phase bridge arm are synchronously turned off; The first lower switch tube and the second lower switch tube of each phase bridge arm are synchronously turned on, and the first upper switch tube, the second upper switch tube, the third upper switch tube, and the third lower switch tube of each phase bridge arm are synchronously turned off; The second upper switch tube and the third upper switch tube of each phase bridge arm are synchronously turned on, and the first upper switch tube, the first lower switch tube, the second lower switch tube, and the third lower switch tube of each phase bridge arm are synchronously turned off; The second lower switch tube and the third lower switch tube of each phase bridge arm are synchronously turned on, and the first upper switch tube, the second upper switch tube, the third upper switch tube and the first lower switch tube of each phase bridge arm are synchronously turned off; The second upper switch tube and the second lower switch tube of each phase bridge arm are synchronously turned on, and the first upper switch tube, the third upper switch tube, the first lower switch tube, and the third lower switch tube of each phase bridge arm are synchronously turned off; The third upper switch tube and the third lower switch tube of each phase bridge arm are turned on synchronously, and the first upper switch tube, the second upper switch tube, the first lower switch tube and the second lower switch tube of each phase bridge arm are turned off synchronously.

[0014] In one embodiment, the driving power supply device includes a driving unit or a frequency converter, the driving unit includes a fixed speed unit or a variable speed unit, the fixed speed unit includes an electrically excited synchronous motor, the variable speed unit includes a doubly fed induction motor, and the step of connecting the driving power supply device to drive the unit stator includes: Controlling the connection switch between the unit and the power grid to turn off, and connecting the drive unit or the frequency converter to the unit stator; The driving unit or the frequency converter is controlled to drive the unit stator in an asynchronous motor mode.

[0015] In a second aspect, the embodiment of the present application further provides a variable speed pumped storage unit starting device, comprising: A control unit, for responding to a pumping start command of the unit, and controlling the excitation converter to short-circuit the unit rotor according to a preset strategy; The drive unit is used to connect the drive power supply device to drive the stator of the unit to increase the speed of the unit to the grid-connected speed.

[0016] In the third aspect, an embodiment of the present application also provides an electric power device, including a controller, a memory, and a computer program stored in the memory and executable on the controller, as well as a first circuit breaker, an excitation converter, a second circuit breaker, a third circuit breaker, a fourth circuit breaker and a frequency converter respectively connected to the controller, wherein the first end of the first circuit breaker, the first end of the second circuit breaker and the first end of the third circuit breaker are connected in common and are used to connect to the power grid through a main transformer, the excitation converter is connected between the second end of the first circuit breaker and the rotor of the variable speed pumped storage unit, the frequency converter is connected between the second end of the second circuit breaker and the first end of the fourth circuit breaker, the second end of the third circuit breaker and the second end of the fourth circuit breaker are connected to the stator of the variable speed pumped storage unit, and when the controller executes the computer program, the steps of the variable speed pumped storage unit starting method as described above are implemented.

[0017] In a fourth aspect, an embodiment of the present application further provides an electric power device, comprising a controller, a memory, and a computer program stored in the memory and executable on the controller, as well as a first switch, a second switch, a third switch and an excitation converter respectively connected to the controller, wherein the first end of the first switch and the first end of the second switch are connected in common and used to be connected to a power grid through a main transformer, the excitation converter is connected between the second end of the first switch and the rotor of a variable speed pumped storage unit, the first end of the third switch is used to connect a driving unit, the second end of the third switch and the second end of the second switch are connected to the stator of the variable speed pumped storage unit, and the controller implements the steps of the variable speed pumped storage unit starting method as described above when executing the computer program.

[0018] Compared with the related art, the embodiments of the present application have the following beneficial effects: The variable speed pumped storage unit starting method of the embodiment of the present application utilizes an excitation converter to short-circuit the unit rotor according to a preset strategy, thereby avoiding the unit losing steps due to excessive acceleration during back-to-back starting or SFC starting, and increasing the starting success rate. In addition, the excitation converter in the system is reused to achieve short-circuiting of the unit rotor, thereby saving costs, and the excitation converter can also be used to actively limit the rotor current. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of an SFC traction power device provided in an embodiment of the present application; Figure 2 A schematic diagram of the structure of a back-to-back dragging electric power device provided in one embodiment of the present application; Figure 3 A flow chart of a variable speed pumped storage unit starting method provided in one embodiment of the present application; Figure 4 A flow chart of a variable speed pumped storage unit starting method provided in a detailed embodiment of the present application; Figure 5 A circuit diagram of a two-level converter provided in one embodiment of the present application; Figure 6 for Figure 5 Schematic diagram of waveform of the wave generation mode of the two-level converter shown; Figure 7 A circuit diagram of a type I NPC three-level converter provided in one embodiment of the present application; Figure 8 for Figure 7 The waveform diagram of the wave generation mode of the I-type NPC three-level converter is shown; Fig. 9 A circuit diagram of an ANPC three-level converter provided in one embodiment of the present application; Fig.10 for Fig. 9 The waveform diagram of the first wave generation mode of the ANPC three-level converter is shown; Fig.11 for Fig. 9 Schematic diagram of waveform of the second wave generation mode of the ANPC three-level converter shown; Fig.12 This is a simulation waveform diagram of the rotor current of a variable speed unit using a periodic switching strategy in a back-to-back starting current control mode; Fig.13 A schematic diagram of a module of a variable speed pumped storage unit starting device provided in one embodiment of the present application; Fig.14A schematic diagram of a module of an electric power device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0022] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0024] In some embodiments, the variable speed (pumped storage) unit uses a doubly fed induction motor (DFIG), and there are two starting methods: one is SFC starting, which is the main method for starting the variable speed unit, and the other is back-to-back starting, which is the backup method for starting the variable speed unit.

[0025] In power equipment, the circuit structure using SFC startup is as follows Figure 1As shown, it includes a first circuit breaker K1, an excitation converter 11, a second circuit breaker K2, a third circuit breaker K3, a fourth circuit breaker K4 and a frequency converter 12. The first end of the first circuit breaker K1, the first end of the second circuit breaker K2 and the first end of the third circuit breaker K3 are connected together and used to be connected to the power grid AC through the main transformer 13. The excitation converter 11 is connected between the second end of the first circuit breaker K1 and the unit rotor of the variable speed pumped storage unit. The frequency converter 12 is connected to the second end of the second circuit breaker K2 and the first end of the fourth circuit breaker K4. The second end of the third circuit breaker K3 and the second end of the fourth circuit breaker K4 are connected to the unit stator of the variable speed pumped storage unit.

[0026] The frequency converter 12 is, for example, an SFC, the first circuit breaker K1 is an AC excitation incoming circuit breaker, the second circuit breaker K2 is an SFC incoming circuit breaker, the third circuit breaker K3 is a grid-connected circuit breaker of a variable speed pumped storage unit, and the fourth circuit breaker K4 is an SFC outlet circuit breaker. Exemplarily, the primary side of the main transformer 13 is connected to the power grid AC, and the secondary side of the main transformer 13 is connected to three branches. The first branch passes through the third circuit breaker K3 to the stator terminal of the variable speed unit; the second branch passes through the first circuit breaker K1, the AC excitation incoming line reactor 14 and the excitation transformer 19 to the grid side of the AC excitation system (including the excitation converter 11), and the machine side of the AC excitation system is directly connected to the terminal of the unit rotor; the third branch is connected to the grid side of the SFC through the second circuit breaker K2, the SFC AC reactor 16 and the SFC transformer 17, and the machine side of the SFC is connected to the terminal of the unit stator through the fourth circuit breaker K4.

[0027] In power equipment, the circuit structure using back-to-back starting is as follows Figure 2 As shown, it includes a first switch S1, a second switch S2, a third switch S3 (including S31, S32, S33) and an excitation converter 11. The first end of the first switch S1 and the first end of the second switch S2 are connected in common and are used to connect to the power grid AC through the main transformer 13. The excitation converter 11 is connected between the second end of the excitation transformer 19 and the unit rotor of the variable speed pumped storage unit. The second end of the first switch S1 is connected to the first end of the excitation transformer 19. The first end of the third switch S3 is used to connect to the drive unit 18. The second end of the third switch S3 and the second end of the second switch S2 are connected to the unit stator of the variable speed pumped storage unit.

[0028] Exemplarily, the drive unit 18 is a fixed speed unit or a variable speed unit, the fixed speed unit includes an electrically excited synchronous motor, and the variable speed unit includes a doubly fed induction motor. Taking the drive unit 18 as a fixed speed unit as an example, it is generally an electrically excited synchronous motor, and the variable speed (pumped storage) unit is a doubly fed induction motor. The first switch S1 includes an AC excitation incoming line circuit breaker, the second switch S2 includes a grid-connected circuit breaker of the variable speed unit, and the third switch S3 includes a fixed speed unit outlet circuit breaker S31, a drag switch S32, and a dragged switch S33. The excitation winding connection terminals of the fixed speed unit are connected to a DC power supply. V f The stator-side connection terminals of the fixed-speed unit are connected to the stator connection terminals of the variable-speed unit through the outlet circuit breaker S31, the drag switch S32 and the dragged switch S33 of the fixed-speed unit. The rotor connection terminals of the variable-speed unit are connected to the secondary side of the main transformer 13 through the second switch S2, and the rotor connection terminals of the variable-speed unit are connected to the machine side of the AC excitation system (including the excitation converter 11), and the grid side of the AC excitation system is connected to the secondary side of the main transformer 13 through the excitation transformer 19, the first switch S1 and the excitation reactor 20.

[0029] Active short-circuit control is to control the switching state of the switching tube of the excitation converter 11 to put the variable speed unit in a continuous rotor short-circuit state or an intermittent short-circuit state so that the unit can start quickly.

[0030] like Figure 3 As shown, an embodiment of the present application provides a variable speed pumped storage unit starting method, comprising: Step S110, in response to the unit pumping start command, controlling the excitation converter to short-circuit the unit rotor according to a preset strategy.

[0031] Exemplarily, when SFC starting is adopted, the first circuit breaker K1, the second circuit breaker K2 and the fourth circuit breaker K4 are closed, and the third circuit breaker K3 is opened. When back-to-back starting is adopted, the first switch S1 and the third switch S3 are closed, and the second switch S2 is opened.

[0032] According to the preset strategy, the active short-circuit control of the unit rotor is achieved by controlling the switching state of the switching tube of the excitation converter 11 to make the unit rotor in a continuous short-circuit state or an intermittent short-circuit state, so that the unit works in an asynchronous motor mode to facilitate rapid start-up of the unit.

[0033] Step S120, turning on the driving power supply device to drive the stator of the unit to increase the speed of the unit to the grid-connected speed.

[0034] The grid-connected speed refers to the rotor speed of the unit that can achieve grid connection of the unit.

[0035] Here, turning on the driving power supply device means turning on, for example, the SFC or the driving unit 18. Figure 1, close the second circuit breaker K2 and the fourth circuit breaker K4, connect the SFC to the unit stator, and use the SFC to drive the unit stator. Figure 2 , turn on the third switch S3 to connect the constant speed unit to the unit stator, and use the constant speed unit to drive the unit stator.

[0036] By using the overexcitation converter 11 to short-circuit the unit rotor, it is made to work in asynchronous motor mode. The driving power supply device drags the variable speed unit to run above the allowable grid-connected speed in asynchronous motor mode, avoiding the disadvantage that the variable speed unit cannot be started quickly when DC power is passed through the rotor side.

[0037] Optionally, the excitation converter can be used to actively limit the rotor current to prevent the unit from losing step or overloading when starting. For example, the conduction time of the switch tube related to the excitation converter can be reduced, that is, the short-circuit time can be reduced. Specifically, the duty cycle of the excitation converter can be reduced.

[0038] See also Figure 4 In one embodiment, before controlling the excitation converter 11 to short-circuit the unit rotor according to a preset strategy in step S110, the variable speed pumped storage unit starting method further includes: Step S210, detecting the operating parameters of the unit.

[0039] The operating parameters include at least one of the rotor current of the unit, the motor temperature, the temperature of the excitation converter 11, and the overload rate of the excitation converter. For example, the operating parameters of the unit can be detected by a detection circuit, such as a mutual inductor. Optionally, the operating parameters also include operating power, which can be calculated by the rotor current and the internal resistance of the unit. The temperature of the excitation converter 11 can also be determined based on the rotor current and the corresponding temperature curve.

[0040] Step S220: When the operating parameter is less than the corresponding parameter threshold, the excitation converter 11 is controlled to short-circuit the unit rotor according to a preset strategy.

[0041] Exemplarily, when the rotor current is less than the current safety threshold minus the hysteresis, step S110 is executed.

[0042] Exemplarily, when the temperature of the excitation converter 11 is less than the temperature safety threshold minus the hysteresis, step S110 is performed. The excitation converter 11 includes one or more of the temperature detection values ​​threatening the safe operation of the converter, such as the temperature of the switch tube and the temperature calculated by the switch tube model.

[0043] Exemplarily, when the overload rate of the excitation converter 11 or the overload rate of the unit is less than the overload rate limit value minus the negative hysteresis, step S110 is performed. The overload rate can be obtained based on at least one of the unit nameplate, load nameplate, rotor current and stator current.

[0044] In one embodiment, after the driving power supply device is turned on to drive the stator of the unit in step S120, the method further includes: When the operating parameter is greater than or equal to the corresponding parameter threshold, the excitation converter 11 is controlled to stop short-circuiting the rotor of the unit.

[0045] Exemplarily, when the rotor current of any phase is greater than the current safety threshold plus the positive hysteresis, the excitation converter 11 is controlled to stop short-circuiting the rotor of the unit, thereby preventing the unit from being damaged due to loss of step or overload.

[0046] Exemplarily, when the motor temperature is greater than the motor temperature safety threshold plus the positive hysteresis, the excitation converter 11 is controlled to stop short-circuiting the unit rotor, thereby preventing the motor from being damaged due to overheating.

[0047] Exemplarily, when the temperature of the excitation converter 11 is greater than the temperature safety threshold plus the positive hysteresis, the excitation converter 11 is controlled to stop short-circuiting the unit rotor, thereby preventing the excitation converter 11 from being damaged due to excessive temperature.

[0048] Exemplarily, when the overload rate of the excitation converter 11 or the overload rate of the unit is greater than the overload rate limit value plus the positive hysteresis, the excitation converter 11 is controlled to stop short-circuiting the unit rotor, thereby preventing the unit from being damaged due to overload.

[0049] See also Figure 5 In some embodiments, the excitation converter 11 includes a two-level converter, wherein the two-level converter includes a three-phase upper bridge arm switch tube T j1(j=a,b,c) And the three-phase lower bridge arm switch tube T j2(j=a,b,c) Understandably, see Figure 5 , switch tube T j1(j=a,b,c) Indicates that the switch tube T is included a1 , switch tube T b1 , switch tube T c1 ; Switching tube T j2(j=a,b,c) Indicates that the switch tube T is included a2 , switch tube T b2 , switch tube T c2 Similar reference numerals in other embodiments and drawings also represent similar meanings, which will not be described in detail below.

[0050] In one embodiment, controlling the excitation converter 11 to short-circuit the unit rotor according to a preset strategy in step S110 includes: Before the unit speed increases to the grid-connected speed, the two-level converter is controlled to alternate between the following two states or maintain any one of the states, so that the unit rotor forms a short-circuit connection.

[0051] State 1: Three-phase upper bridge arm switch tube T j1(j=a,b,c) Synchronous normally conducting, three-phase lower bridge arm switch tube Tj2(j=a,b,c) Synchronous normally off state.

[0052] State 2: Three-phase upper bridge arm switch tube T j1(j=a,b,c) Synchronous normally off, three-phase lower bridge arm switch tube T j2(j=a,b,c) Synchronous normally-on state.

[0053] Among them, controlling the two-level converter to maintain any one state is a normally-on strategy, for example, maintaining in state 1 or state 2. Controlling the two-level converter to alternate between the two states is a periodic switching strategy. The waveform diagram of the wave-generating mode of controlling the three-phase bridge arm switch tube under the periodic switching strategy is shown in FIG. Figure 6 As shown, it switches back and forth between state 1 and state 2. There is a dead zone between state 1 and state 2. The dwell time of each state is about 1 / 2 of the switching cycle. After the active short-circuit control is turned off, it switches to state 0. Correspondingly, the three-phase upper bridge arm switch tube T j1(j=a,b,c) , three-phase lower bridge arm switch tube T j2(j=a,b,c) The switching states are shown in Table 1 below, where in each state, 1 represents on and 0 represents off.

[0054] Table 1, switch status of two-level converter:

[0055] See also Figure 7 In one embodiment, the excitation converter 11 includes a type I NPC (Neutral Point Clamped) three-level converter or a type II NPC three-level converter. Figure 7 As shown, taking the I-type NPC three-level converter as an example, the I-type NPC three-level converter includes: a three-phase upper bridge arm switch tube T j1(j=a,b,c) ,T j2(j=a,b,c) , three-phase lower bridge arm switch tube T j3(j=a,b,c) ,T j4(j=a,b,c) , zero-level pass diode D of the three-phase upper bridge arm j5(j=a,b,c) , zero-level pass diode D of the three-phase lower bridge arm j6(j=a,b,c) Type II NPC three-level converter is a T-type three-level converter.

[0056] Controlling the excitation converter 11 to short-circuit the unit rotor according to a preset strategy in step S110 includes: Before the unit speed increases to the grid-connected speed, in each switching cycle, the type I NPC three-level converter or the type II NPC three-level converter is controlled to alternate between the following three states or maintain any one of the states, so that the unit rotor forms a short-circuit connection.

[0057] State A: The switches of the three-phase upper bridge arm are turned on synchronously. j1(j=a,b,c) ,T j2(j=a,b,c), the switch tube T of the three-phase lower bridge arm j3(j=a,b,c) ,T j4(j=a,b,c) Synchronous shutdown.

[0058] State B: Switch tube T of the three-phase lower bridge arm j1(j=a,b,c) ,T j2(j=a,b,c) Synchronous conduction, three-phase upper bridge arm switch tube T j3(j=a,b,c) ,T j4(j=a,b,c) Synchronous shutdown.

[0059] State C: Only the three-phase zero-level path is synchronously turned on, that is, the three-phase upper bridge arm switch tube T j2(j=a,b,c) , the switch tube T of the three-phase lower bridge arm j3(j=a,b,c) Conductivity.

[0060] The normally-on strategy is to control the type I NPC three-level converter or the type II NPC three-level converter to maintain any one state, for example, to maintain the state A, state B or state C.

[0061] The I-type NPC three-level excitation converter 11 is controlled to alternately switch between the three states in sequence under the periodic switching strategy. The waveform diagram of the wave-generating mode of the three-phase bridge arm switch tube under the periodic switching strategy is shown in FIG. Figure 8 As shown, the switch states of the three-phase bridge arm switch tube are shown in Table 2. Exemplarily, in each switching cycle, it is in state 0 at the beginning, and after executing step S110, it switches to state A, then switches to state C, then switches to state B, and then switches to state C. Among them, the stay time of state A, state B and state C accounts for 1 / 4, 1 / 4 and 1 / 2 of the switching cycle respectively. If the short-circuit control stops, it switches to state 0.

[0062] Table 2, switch status of type I NPC three-level converter:

[0063] See also Fig. 9 In one embodiment, the excitation converter 11 includes an ANPC (Active Neutral Point Clamped) three-level converter, and the ANPC three-level converter includes three-phase bridge arms, and each phase bridge arm includes: The first upper switch tube T connected in series between the bus midpoint and the bus positive pole j1(j=a,b,c) , the second upper switch tube T j2(j=a,b,c) ; The first lower switch tube T connected in series between the negative pole of the bus and the midpoint of the bus j4(j=a,b,c) , the second lower switch tube T j3(j=a,b,c) ; Connected to the two switch tubes T in the upper bridge arm j1(j=a,b,c) and T j2(j=a,b,c)The third upper switch tube T between the series connection point and the bus midpoint j5(j=a,b,c) ;as well as, Connected to the two switch tubes T in the lower bridge arm j3(j=a,b,c) and T j4(j=a,b,c) The third lower switch tube T between the series connection point and the bus midpoint j6(j=a,b,c) .

[0064] Controlling the excitation converter 11 to short-circuit the unit rotor according to a preset strategy in step S110 includes: Before the unit speed increases to the grid-connected speed, in each switching cycle, the ANPC three-level converter is controlled to alternate in the following states or maintain in any one state in sequence, so that the unit rotor forms a short-circuit connection.

[0065] State 1: The first upper switch tube T of each phase bridge arm j1(j=a,b,c) , the second upper switch tube T j2(j=a,b,c) Synchronously conduct, the third upper switch tube T of each phase bridge arm j5(j=a,b,c) , the first lower switch tube T j4(j=a,b,c) , the second lower switch tube T j3(j=a,b,c) , the third lower switch tube T j6(j=a,b,c) Synchronous shutdown; State 2: The first lower switch tube T of each phase bridge arm j4(j=a,b,c) , the second lower switch tube T j3(j=a,b,c) Synchronously conduct, the first upper switch tube T of each phase bridge arm j1(j=a,b,c) , the second upper switch tube T j2(j=a,b,c) , the third upper switch tube T j5(j=a,b,c) , the third lower switch tube T j6(j=a,b,c) Synchronous shutdown; State 3: The second upper switch tube T of each phase bridge arm j2(j=a,b,c) , the third upper switch tube T j5(j=a,b,c) Synchronously conduct, the first upper switch tube T of each phase bridge arm j1(j=a,b,c) , the first lower switch tube T j4(j=a,b,c) , the second lower switch tube T j3(j=a,b,c) , the third lower switch tube T j6(j=a,b,c) Synchronous shutdown; State 4: The second lower switch tube T of each phase bridge arm j3(j=a,b,c) , the third lower switch tube T j6(j=a,b,c) Synchronously conduct, the first upper switch tube T of each phase bridge arm j1(j=a,b,c) , the second upper switch tube T j2(j=a,b,c) , the third upper switch tube T j5(j=a,b,c) , the first lower switch tube T j4(j=a,b,c) Synchronous shutdown; State 5: The second upper switch tube T of each phase bridge arm j2(j=a,b,c) , the second lower switch tube T j3(j=a,b,c) Synchronously conduct, the first upper switch tube T of each phase bridge armj1(j=a,b,c) , the third upper switch tube T j5(j=a,b,c) , the first lower switch tube T j4(j=a,b,c) , the third lower switch tube T j6(j=a,b,c) Synchronous shutdown; State 6: The third upper switch tube T of each phase bridge arm j5(j=a,b,c) , the third lower switch tube T j6(j=a,b,c) Synchronously conduct, the first upper switch tube T of each phase bridge arm j1(j=a,b,c) , the second upper switch tube T j2(j=a,b,c) , the first lower switch tube T j4(j=a,b,c) , the second lower switch tube is turned off synchronously.

[0066] The ANPC three-level converter is controlled to maintain any state, that is, a normally-on strategy, for example, maintaining the ANPC three-level converter in state one, state two, state three, state four, state five or state six.

[0067] The ANPC three-level excitation converter 11 is controlled to alternately switch between the six states in sequence under the periodic switching strategy. The waveform diagram of the wave-generating mode of the three-phase bridge arm switch tube under the periodic switching strategy is shown in FIG. Fig.10 , Fig.11 As shown, the switching states of the three-phase bridge arm switch tubes are shown in Table 3 below.

[0068] There are two wave generation modes for controlling the ANPC three-level excitation converter 11 under the periodic switching strategy, and the effects are the same. The waveform diagram of the first wave generation mode is as follows: Fig.10 As shown, in the first wave-generating mode, the wave-generating state is initially in state zero. In each switching cycle: after the short-circuit control of step S110 is turned on, it switches to state one, then to state three, then to state six, then to state four, then to state two, then to state five, and then switches to state zero after the short-circuit control is turned off. The dwell time of each state in state one to six accounts for 1 / 6 of the switching cycle. The waveform diagram of the second wave-generating mode is shown in FIG. Fig.11 As shown, in the second wave-generating mode, the wave-generating state is initially in state zero. In each switching cycle: after the short-circuit control of step S110 is turned on, it switches to state one, then switches to state five, then switches to state two, then switches to state four, then switches to state six, then switches to state three, and switches to state zero after the short-circuit control is turned off, wherein the residence time of each state from state one to state six accounts for 1 / 6 of the switching cycle.

[0069] Table 3, switch status of ANPC three-level converter:

[0070] It can be understood that in each embodiment of the above step S110 in which the excitation converter 11 is controlled to short-circuit the rotor of the unit according to a preset strategy, the periodic switching strategy is faster than the normal-on strategy for the starting speed of the unit.

[0071] In one embodiment, the step S120 of connecting the driving power supply device to drive the stator of the unit includes: The connection switch between the control unit and the power grid AC is turned off, and the drive unit or the inverter 12 is connected to the unit stator.

[0072] Specifically, refer to Figure 1 , close the second circuit breaker K2 and the fourth circuit breaker K4, connect the SFC to the unit stator, and use the SFC to drive the unit stator. Figure 2 , turn on the third switch S3 to connect the constant speed unit to the unit stator, and use the constant speed unit to drive the unit stator.

[0073] The drive unit 18 or the frequency converter 12 is controlled to drive the unit stator in an asynchronous motor mode.

[0074] The excitation winding connection terminal of the drive unit (e.g., fixed speed unit) 18 is connected to the DC power supply V f The connection terminals on the rotor side of the variable speed unit are short-circuited through the excitation converter 11, the movable guide vanes of the turbine slowly open, the water flow impacts the turbine of the fixed speed unit, the rotor of the fixed speed unit starts to rotate, and the stator side emits three-phase alternating current with slowly increasing frequency and amplitude to drive the variable speed unit. The speed of the rotor of the variable speed unit starts to rise until the speed reaches a speed above the speed allowed for grid connection.

[0075] Unlike the start-up of a fixed-speed unit, the variable-speed unit cannot be completely equivalent to a traditional electrically excited synchronous motor after the unit rotor is powered by DC, because there is no damping winding, so it cannot start quickly. Therefore, in another example, the unit rotor is short-circuited to make it work in asynchronous motor mode. The SFC drives the variable-speed unit in asynchronous motor mode to run above the grid-connected speed, avoiding the disadvantage that the variable-speed unit rotor side cannot start quickly when DC is powered.

[0076] Generally speaking, starting a variable speed unit in back-to-back starting mode is much more difficult than SFC. If back-to-back starting can be successful, SFC starting will also be no problem. Moreover, the start-up conditions and wave generation strategies of short-circuit control of SFC starting and back-to-back starting are consistent.

[0077] Matlab / Simulink is used to simulate the back-to-back start of the variable speed unit, and the control strategy of the rotor current operating parameters of step S210 and step 220 is added. In step S110, the control excitation converter 11 is short-circuited in the unit rotor according to the preset strategy. The switch tube cycle switching strategy of the control excitation converter 11 is used, and the current safety threshold is set to 500A. The rotor current simulation results are as follows: Fig.12 As shown, the unit starts quickly and stably.

[0078] In some embodiments, the startup method further comprises the following steps: Step S310, in response to the unit speed increasing to the grid-connected speed, the excitation converter 11 is controlled to stop short-circuiting the unit rotor.

[0079] Step S320, controlling the excitation converter 11 to excite the rotor of the unit, connecting the stator of the unit to the secondary side of the main transformer 13 to complete the grid connection.

[0080] Specifically, the drive makes the stator voltage of the unit synchronize with the amplitude, frequency and phase of the grid AC voltage, refer to Figure 1 , connect the stator of the unit and the secondary side of the main transformer 13, that is, close the third circuit breaker K3; at the same time, the second circuit breaker K2 and the fourth circuit breaker K4 can be turned off. Figure 2 , connect the stator of the unit and the secondary side of the main transformer 13, that is, close the second switch S2; keep the first switch S1 to the closed state; at the same time, the third switch S3 can be opened, and the grid connection process is completed.

[0081] Step S330, entering the water pumping control phase.

[0082] That is, the excitation converter 11 enters the normal vector control of the unit. The normal vector control is used in the pumping control stage, and the active power and reactive power are decoupled. The user can freely set the active power set value and the reactive power set value, that is, the active power of the grid AC can be absorbed to realize pumped storage, and reactive power can be sent to the grid AC, or reactive power can be absorbed from the grid AC.

[0083] See also Fig.13 In a second aspect, the present application also provides a variable speed pumped storage unit starting device, comprising: The control unit 110 is used to control the excitation converter 11 to short-circuit the rotor of the unit according to a preset strategy in response to a pumping start command of the unit; The driving unit 120 is used to connect the driving power supply device to drive the stator of the unit to increase the speed of the unit to the grid-connected speed.

[0084] When the pumping condition is started, the full-bridge specific switch tube of the control excitation converter 11 is turned on to short-circuit the unit rotor, which is equivalent to a squirrel cage asynchronous motor, and can realize SFC or back-to-back fast start of the variable speed unit. If the rotor current, motor temperature, excitation converter temperature or excitation converter overload rate is too high during the startup process, the switch tube is temporarily turned off, and the rotor current, motor temperature, excitation converter temperature or excitation converter overload rate is reduced before it is put into operation.

[0085] See also Figure 1 and Fig.14 In a third aspect, an embodiment of the present application further provides an electric power device 140, including a controller 141, a memory 142, and a computer program 1421 stored in the memory 142 and executable on the controller 141, and a first circuit breaker K1, an excitation converter 11, a second circuit breaker K2, a third circuit breaker K3, a fourth circuit breaker K4, and a frequency converter 12 respectively connected to the controller 141, wherein a first end of the first circuit breaker K1, a first end of the second circuit breaker K2, and a first end of the third circuit breaker K3 are connected in common. , and is used to be connected to the power grid AC through the main transformer 13, the excitation converter 11 is connected between the second end of the first circuit breaker K1 and the unit rotor of the variable speed pumped storage unit, the frequency converter 12 is connected to the second end of the second circuit breaker K2 and the first end of the fourth circuit breaker K4, the second end of the third circuit breaker K3 and the second end of the fourth circuit breaker K4 are connected to the unit stator of the variable speed pumped storage unit, and the controller 141 implements the steps of the variable speed pumped storage unit starting method in any of the above embodiments when executing the computer program 1421.

[0086] See also Figure 2 and Fig.14 In a fourth aspect, an embodiment of the present application further provides an electric power device 140, comprising a controller 141, a memory 142, and a computer program 1421 stored in the memory 142 and executable on the controller 141, as well as a first switch S1, a second switch S2, a third switch S3 and an excitation converter 11 respectively connected to the controller 141, wherein a first end of the first switch S1 and a first end of the second switch S2 are connected in common and used to be connected to the power grid AC through a main transformer 13, the excitation converter 11 is connected between a second end of the first switch S1 and a rotor of the variable speed pumped storage unit, a first end of the third switch S3 is used to connect to a drive unit 18, a second end of the third switch S3 and a second end of the second switch S2 are connected to a stator of the variable speed pumped storage unit, and when the controller 141 executes the computer program 1421, the steps of the variable speed pumped storage unit starting method in any of the above embodiments are implemented.

[0087] Those skilled in the art will understand that Fig.14This is merely an example of the power device 140 and does not constitute a limitation on the power device 140 . The power device 140 may include more or fewer components than shown in the figure, or a combination of certain components, or different components, such as input and output devices, network access devices, etc.

[0088] The controller 141 may be a central processing unit (CPU), or other general controllers 141, digital signal processors 141 (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general controller 141 may be a microcontroller 141 or any conventional controller 141.

[0089] In some embodiments, the memory 142 may be an internal storage unit of the power device 140, such as a hard disk or memory of the power device 140. In other embodiments, the memory 142 may also be an external storage device of the power device 140, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the power device 140. Further, the memory 142 may also include both an internal storage unit of the power device 140 and an external storage device. The memory 142 is used to store an operating system, an application program, a boot loader, data, and other programs. The memory 142 may also be used to temporarily store data that has been output or is to be output.

[0090] The embodiment of the present application further provides a computer-readable storage medium, which stores a computer program 1421 . When the computer program 1421 is executed by the controller 141 , the steps in the above-mentioned method embodiments can be implemented.

[0091] The embodiment of the present application provides a computer program 1421 product, which, when executed on a computer, enables the computer to execute the steps in the above-mentioned method embodiments.

[0092] If the integrated unit is implemented in the form of 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, the present application implements all or part of the processes in the above method embodiments, which can be completed by instructing the relevant hardware through a computer program 1421. The computer program 1421 can be stored in a computer-readable storage medium. When the computer program 1421 is executed by the controller 141, the steps of the above method embodiments can be implemented. Among them, the computer program 1421 includes a computer program 1421 code, and the computer program 1421 code can be in source code form, object code form, executable file or some intermediate form. The computer readable medium may at least include: any entity or device that can carry the computer program 1421 code to the camera device / terminal device, a recording medium, a computer memory 142, a ROM (Read-Only Memory, read-only memory 142), a RAM (Random Access Memory, random access memory 142), a CD-ROM (Compact Disc Read-Only Memory, read-only optical disc), a magnetic tape, a floppy disk and an optical data storage device. The computer-readable storage medium mentioned in the present application may be a non-volatile storage medium, in other words, a non-transitory storage medium.

[0093] It should be understood that all or part of the steps to implement the above embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program 1421 product. The computer program 1421 product includes one or more computer instructions. The computer instructions can be stored in the above-mentioned computer readable storage medium.

[0094] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0095] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0096] In the embodiments provided in the present 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 schematic. For example, the division of modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0097] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0098] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A variable speed pumped storage unit starting method, characterized in that: include: In response to the unit pumping start command, the excitation converter is controlled to short-circuit the unit rotor according to a preset strategy; Turn on the drive power supply device to drive the stator of the unit to increase the speed of the unit to the grid-connected speed.

2. The startup method according to claim 1, characterized in that: Before controlling the excitation converter to short-circuit the unit rotor according to a preset strategy, the method further includes: detecting operating parameters of the unit; When the operating parameter is less than the corresponding parameter threshold, the excitation converter is controlled to short-circuit the unit rotor according to a preset strategy.

3. The startup method according to claim 2, characterized in that: After the driving power supply device is turned on to drive the stator of the unit, the method further includes: When the operating parameter is greater than or equal to the corresponding parameter threshold, the excitation converter is controlled to stop short-circuiting the unit rotor.

4. The startup method according to claim 2 or 3, characterized in that: The detected operating parameters of the unit include at least one of the rotor current, motor temperature, excitation converter temperature, and excitation converter overload rate of the unit.

5. The startup method according to any one of claims 1 to 3, characterized in that: The excitation converter includes a two-level converter, and the control excitation converter is used to short-circuit the rotor of the unit according to a preset strategy, including: Before the unit speed increases to the grid-connected speed, the two-level converter is controlled to alternate between the following two states or maintain any one of the states: The three-phase upper bridge arm switch tubes are synchronously normally turned on, and the three-phase lower bridge arm switch tubes are synchronously normally turned off; The three-phase upper bridge arm switch tubes are synchronously normally turned off, and the three-phase lower bridge arm switch tubes are synchronously normally turned on.

6. The starting method according to any one of claims 1 to 3, characterized in that: The excitation converter includes a type I NPC three-level converter or a type II NPC three-level converter, and the control excitation converter is used to short-circuit the unit rotor according to a preset strategy, including: Before the unit speed increases to the grid-connected speed, in each switching cycle, the type I NPC three-level converter or the type II NPC three-level converter is controlled to alternate between the following three states or maintain any one of the states: The switch tubes of the three-phase upper bridge arm are turned on synchronously, and the switch tubes of the three-phase lower bridge arm are turned off synchronously; The switch tubes of the three-phase lower bridge arm are turned on synchronously, and the switch tubes of the three-phase upper bridge arm are turned off synchronously; Only the three-phase zero-level paths are turned on synchronously.

7. The startup method according to any one of claims 1 to 3, characterized in that: The excitation converter comprises an ANPC three-level converter, and the ANPC three-level converter comprises three-phase bridge arms, and each phase bridge arm comprises: A first upper switch tube and a second upper switch tube connected in series between the bus midpoint and the bus positive electrode; A first lower switch tube and a second lower switch tube connected in series between the negative electrode of the busbar and the midpoint of the busbar; A third upper switch tube, the third upper switch tube being connected between a series connection point between the first upper switch tube and the second upper switch tube and a midpoint of the busbar; and A third lower switch tube, the third lower switch tube being connected between a series connection point between the first lower switch tube and the second lower switch tube and a midpoint of the busbar; The controlling the excitation converter to short-circuit the unit rotor according to a preset strategy includes: Before the unit speed increases to the grid-connected speed, in each switching cycle, the ANPC three-level converter is controlled to alternate between the following six states or to maintain any one of the states: The first upper switch tube and the second upper switch tube of each phase bridge arm are synchronously turned on, and the third upper switch tube, the first lower switch tube, the second lower switch tube, and the third lower switch tube of each phase bridge arm are synchronously turned off; The first lower switch tube and the second lower switch tube of each phase bridge arm are synchronously turned on, and the first upper switch tube, the second upper switch tube, the third upper switch tube, and the third lower switch tube of each phase bridge arm are synchronously turned off; The second upper switch tube and the third upper switch tube of each phase bridge arm are synchronously turned on, and the first upper switch tube, the first lower switch tube, the second lower switch tube, and the third lower switch tube of each phase bridge arm are synchronously turned off; The second lower switch tube and the third lower switch tube of each phase bridge arm are synchronously turned on, and the first upper switch tube, the second upper switch tube, the third upper switch tube and the first lower switch tube of each phase bridge arm are synchronously turned off; The second upper switch tube and the second lower switch tube of each phase bridge arm are synchronously turned on, and the first upper switch tube, the third upper switch tube, the first lower switch tube, and the third lower switch tube of each phase bridge arm are synchronously turned off; The third upper switch tube and the third lower switch tube of each phase bridge arm are turned on synchronously, and the first upper switch tube, the second upper switch tube, the first lower switch tube and the second lower switch tube of each phase bridge arm are turned off synchronously.

8. The startup method according to any one of claims 1 to 3, characterized in that: The driving power supply device includes a driving unit or a frequency converter, the driving unit includes a fixed speed unit or a variable speed unit, the fixed speed unit includes an electrically excited synchronous motor, the variable speed unit includes a double-fed induction motor, and the connecting of the driving power supply device to drive the unit stator includes: Controlling the connection switch between the unit and the power grid to turn off, and connecting the drive unit or the frequency converter to the unit stator; The driving unit or the frequency converter is controlled to drive the unit stator in an asynchronous motor mode.

9. A variable speed pumped storage unit starting device, characterized in that: include: A control unit, for responding to a pumping start command of the unit, and controlling the excitation converter to short-circuit the unit rotor according to a preset strategy; The drive unit is used to connect the drive power supply device to drive the stator of the unit to increase the speed of the unit to the grid-connected speed.

10. An electric power device, characterized in that: The invention comprises a controller, a memory, and a computer program stored in the memory and executable on the controller, and a first circuit breaker, an excitation converter, a second circuit breaker, a third circuit breaker, a fourth circuit breaker, and a frequency converter respectively connected to the controller, wherein the first end of the first circuit breaker, the first end of the second circuit breaker, and the first end of the third circuit breaker are connected in common and are used to be connected to a power grid through a main transformer, the excitation converter is connected between the second end of the first circuit breaker and the rotor of a variable-speed pumped-storage unit, the frequency converter is connected between the second end of the second circuit breaker and the first end of the fourth circuit breaker, the second end of the third circuit breaker and the second end of the fourth circuit breaker are connected to the stator of the variable-speed pumped-storage unit, and the controller implements any one of claims 1 to 8 when executing the computer program. or, comprising a controller, a memory, and a computer program stored in the memory and executable on the controller, and a first switch, a second switch, a third switch and an excitation converter respectively connected to the controller, wherein the first end of the first switch and the first end of the second switch are connected in common and used to be connected to the power grid through the main transformer, the excitation converter is connected between the second end of the first switch and the rotor of the variable speed pumped storage unit, the first end of the third switch is used to connect the drive unit, the second end of the third switch and the second end of the second switch are connected to the stator of the variable speed pumped storage unit, and the controller implements the steps of the variable speed pumped storage unit starting method as described in any one of claims 1 to 8 when executing the computer program.

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