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, a crowbar device is connected into a variable-speed unit rotor, so that a unit works in an asynchronous motor mode, the situation that the unit is out of step due to the fact that acceleration is too fast during back-to-back starting and SFC starting is avoided, and the starting success rate is increased.

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] Considering the cost, environment, benefits and maturity, pumped storage is currently the most effective, practical and commercially valuable energy storage method in the operation and control of large power grids. 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 to operate at the optimal speed at all times. The variable speed unit can adjust the speed of the motor within a certain range to adapt to a wider head change, 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 working voltage is synchronized with the grid working 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 working 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 unit of the power station or an adjacent power station is used to start the doubly fed unit. The stators of the conventional unit and the doubly fed unit are electrically connected to each other through the starting bus. The conventional unit can be a fixed speed unit or a variable speed unit. The fixed speed unit includes but is not limited to an electrically excited synchronous motor, and the variable speed unit includes but is not limited to a doubly fed induction motor. Taking the fixed speed unit as an example, the rotors of the fixed speed unit and the doubly fed unit are respectively added with DC excitation. The conventional unit uses the water flow to impact the turbine to rotate and generate AC voltage, 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 a variable frequency AC power supply 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] However, due to the different structure of the variable speed unit and the fixed speed unit, the starting method of the fixed speed unit cannot be directly used, otherwise it is easy to cause speed oscillation. A variable speed pumped storage unit in the prior art uses an AC excitation system and a unit self-starting method, short-circuiting the stator side of the double-fed induction motor, and connecting the AC excitation system to the rotor side for self-starting. However, the stator and rotor leakage inductance of the motor equivalent to the rotor side are large, which limits the processing capacity of the high-speed section, resulting in a long self-starting acceleration time, or the inability to reach the grid-connected speed. 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 a pumping start command of the unit, the crowbar device is connected to the rotor of the unit according to a preset strategy, so that the unit is equivalent to a squirrel cage asynchronous motor; 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, the connecting the crowbar device to the unit rotor according to a preset strategy includes: Before the unit is accelerated to the grid-connected speed, the crowbar device is always connected to the unit rotor; or Before the unit is accelerated to the grid-connected speed, the crowbar device is intermittently connected to the unit rotor according to a preset period.

[0009] In one embodiment, the connecting the crowbar device to the unit rotor according to a preset strategy further includes: detecting operating parameters of the crowbar device; Before the unit is accelerated to the grid-connected speed and when the operating parameter is less than the corresponding parameter threshold, the crowbar device is connected to the unit rotor.

[0010] In one of the embodiments, the connecting the crowbar device to the unit rotor according to a preset strategy also includes: Before the unit speed increases to the grid-connected speed and when the operating parameter is greater than or equal to the corresponding parameter threshold, the connection between the crowbar device and the unit rotor is disconnected.

[0011] In one of the embodiments, the operating parameters include at least one of the operating current, operating voltage, operating temperature and unit temperature of the crowbar device.

[0012] In one embodiment, before the crowbar device is connected to the rotor of the unit according to a preset strategy in response to the unit pumping start command, the method includes: Determine an actual crowbar resistance value corresponding to the maximum starting torque of the rotor of the unit according to the parameters of the unit and the parameters of the crowbar device; Obtaining a resistance value range of the crowbar device applicable to the unit in a low voltage ride-through condition, wherein the resistance value range includes a lower resistance limit value and an upper resistance limit value; The resistance value of the crowbar device is determined according to the resistance value range and the actual crowbar resistance value corresponding to the maximum starting torque.

[0013] In one embodiment, determining the value of the crowbar device according to the resistance value range and the actual crowbar resistance corresponding to the maximum starting torque includes: When the actual crowbar resistance value corresponding to the maximum starting torque is less than the resistance lower limit value, the resistance value of the crowbar device is taken as the resistance lower limit value; When the actual crowbar resistance value corresponding to the maximum starting torque is greater than the resistance upper limit value, the resistance value of the crowbar device is set to the resistance upper limit value; When the upper resistance limit is not less than the actual crowbar resistance value corresponding to the maximum starting torque and the actual crowbar resistance value corresponding to the maximum starting torque is not less than the lower resistance limit, the resistance value of the crowbar device is the actual crowbar resistance value corresponding to the maximum starting torque.

[0014] In one embodiment, determining the actual crowbar resistance value corresponding to the maximum starting torque of the rotor of the unit according to the parameters of the unit and the parameters of the crowbar device includes: Obtaining the mechanical torque of the unit according to the parameters of the unit and the parameters of the crowbar device; Draw a mechanical characteristic curve of the unit according to the expression of the mechanical torque of the unit to obtain the starting torque of the unit; The actual crowbar resistance value corresponding to the maximum starting torque of the rotor of the unit is obtained according to the starting torque of the unit.

[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 connecting the crowbar device to the rotor of the unit according to a preset strategy, so that the unit is equivalent to a squirrel cage asynchronous motor; 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 a third aspect, an embodiment of the present application further provides an electric power device, comprising an isolation transformer, an excitation transformer, a controller, a memory, and a computer program stored in the memory and executable on the controller, as well as a crowbar device, a first circuit breaker, a second circuit breaker, a third circuit breaker, a fourth circuit breaker, an excitation converter, 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 excitation transformer are connected in common and connected to a power grid through an isolation transformer, and the second end of the first circuit breaker is connected to the stator of the variable speed pumped storage unit. , the second end of the second circuit breaker is connected to the first end of the frequency converter, the second end of the frequency converter is connected to the stator of the unit through the third circuit breaker, the first end of the excitation converter is connected to the second end of the isolation transformer through the excitation transformer, the second end of the excitation converter is connected to the unit rotor of the variable speed pumped storage unit, the crowbar device is connected to the unit rotor, the first end of the fourth circuit breaker is connected to the drive unit, the second end of the fourth circuit breaker is connected to the unit stator, and the controller implements the steps of the variable speed pumped storage unit starting method as described above when executing the computer program.

[0017] 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 connects the variable speed unit rotor through a crowbar device, so that the unit works in an asynchronous motor mode, avoids the unit losing step due to excessive acceleration during back-to-back starting and SFC starting, and increases the starting success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of an electric power device provided in one embodiment of the present application; Figure 2 A flow chart of a variable speed pumped storage unit starting method provided in one embodiment of the present application; Figure 3 A circuit structure diagram of a crowbar device provided in one embodiment of the present application; Figure 4 A circuit structure diagram of a crowbar device provided in one embodiment of the present application; Figure 5 A flow chart of a variable speed pumped storage unit starting method provided in one embodiment of the present application; Figure 6 A steady-state equivalent circuit diagram of a crowbar device provided in one embodiment of the present application connected to a rotor of a unit; Figure 7 A mechanical characteristic curve for starting a variable speed pumped storage unit provided in an embodiment of the present application; Figure 8 A schematic diagram of a module of a variable speed pumped storage unit starting device provided in one embodiment of the present application; Fig. 9 A schematic diagram of a module of an electric power device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] In power equipment, a circuit structure compatible with back-to-back starting and SFC starting is used, such as Figure 1As shown, it includes an isolation transformer 11, an excitation transformer 12, a crowbar device 13, a first circuit breaker QF1, a second circuit breaker QF2, a third circuit breaker QF3, a fourth circuit breaker QF4, an excitation converter 14 and a frequency converter 15. The first end of the first circuit breaker QF1, the first end of the second circuit breaker QF2, and the first end of the excitation transformer 12 are connected together and connected to the power grid AC through the isolation transformer 11. The second end of the first circuit breaker QF1 is connected to the variable speed pumped storage unit (hereinafter referred to as the variable speed unit or unit) 10. The second end of the second circuit breaker QF2 is connected to the first end of the frequency converter 15, the second end of the frequency converter 15 is connected to the stator of the unit through the third circuit breaker QF3, the first end of the excitation converter 14 is connected to the second end of the isolation transformer 11 through the excitation transformer 12, the second end of the excitation converter 14 is connected to the unit rotor of the variable speed pumped storage unit 10, the crowbar device 13 is connected to the rotor of the unit 10, the first end of the fourth circuit breaker QF4 is connected to the drive unit 20, and the second end of the fourth circuit breaker QF4 is connected to the stator of the unit.

[0025] In which, illustratively, the drive unit 20 is a fixed speed unit or a variable speed unit. The fixed speed unit is generally an electrically excited synchronous motor, and the variable speed unit is generally a double-fed induction motor. For example, taking the fixed speed unit as an example, the fixed speed unit uses an electrically excited synchronous motor, and the variable speed (pumped storage) unit 10 is a double-fed induction motor. The excitation winding terminal of the drive unit 10 is connected to the DC power supply U f The frequency converter 15 is an SFC frequency converter.

[0026] The purpose of the variable speed pumped storage unit starting method in the embodiment of the present application is to connect the crowbar device 13 to the unit rotor when the pumping mode of the unit 10 is started, and the unit 10 can be equivalent to a squirrel cage asynchronous motor. During SFC or back-to-back starting, the unit is driven in asynchronous motor mode.

[0027] Active short-circuit control is to control the switching state of the switching tube of the excitation converter 14 to put the variable speed unit 10 in a continuous rotor short-circuit state or an intermittent short-circuit state so that the unit 10 can start quickly.

[0028] like Figure 2 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, the crowbar device is connected to the unit rotor according to a preset strategy, so that the unit is equivalent to a squirrel cage asynchronous motor.

[0029] The crowbar device 13 is connected to the rotor of the unit, and is in parallel with the AC excitation converter 14. The crowbar device 13 access mode includes access during the entire startup process, intermittent access during the startup process according to a period, intermittent access during the startup process according to the size of the working current, intermittent access during the startup process according to the size of the working voltage, and intermittent access during the startup process according to the size of the working temperature.

[0030] 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.

[0031] The grid-connected speed refers to the rotor speed of the unit that can achieve grid connection of the unit.

[0032] Among them, turning on the driving power supply device means turning on, for example, the frequency converter 15 or the driving unit 20. The driving unit 20 is a constant speed unit or a variable speed unit. The constant speed unit includes but is not limited to an electrically excited synchronous motor, and the variable speed unit includes but is not limited to a doubly fed induction motor. Taking the constant speed unit as an example, it is an electrically excited synchronous motor.

[0033] Exemplarily, during back-to-back starting, the second circuit breaker QF2 and the third circuit breaker QF3 are constantly open, and the fourth circuit breaker QF4 is closed, the rotor of the driving unit 20 is excited, and the water flow impacts the turbine of the driving unit 20, driving the rotor of the driving unit 20 to rotate, rising from zero speed to the rated speed, and the amplitude and frequency of the stator output voltage of the driving unit 20 gradually increase, driving the speed of the variable speed unit 10 to increase, and this process is equivalent to constant voltage-frequency ratio control; when the speed of the variable speed unit 10 enters the normal operating speed range, the start-up is completed, the fourth circuit breaker QF4 is disconnected, the movable guide vanes of the turbine of the driving unit 20 are closed, and the DC exciter stops excitation.

[0034] For example, when the SFC is started, the second circuit breaker QF2 and the third circuit breaker QF3 are always closed, the fourth circuit breaker QF4 is always opened, the frequency converter 15 is started, and the output current drives the speed of the variable speed unit 10 to increase. When the speed of the variable speed unit 10 enters the normal operating speed range, the start-up is completed, the second circuit breaker QF2 and the third circuit breaker QF3 are opened, the frequency converter 15 stops running, and there is no voltage output.

[0035] It is understandable that the crowbar device 13 is a protective electronic circuit device that limits voltage and current and is installed at the rotor end. Generally, when the stator voltage of the unit drops, the crowbar device 13 is used to absorb the magnetic field energy of the unit 10 to prevent the energy from being fed back to the excitation converter 14 and causing system failure. In the embodiment of the present application, when the unit 10 is started, the crowbar device 13 is connected to the unit rotor. What is different from the conventional method is that the unit 10 is equivalent to a squirrel cage asynchronous motor. The unit 10 can be quickly started when working in the asynchronous motor mode under the SFC or back-to-back starting mode, and it can avoid the unit 10 from losing step due to excessive acceleration at the start, thereby increasing the success rate of starting.

[0036] like Figure 3 , Figure 4 As shown, the crowbar device 13 has two circuit structures. Figure 3 Shown is a three-resistor crowbar arrangement, Figure 4 The single resistor crowbar device is shown. Both types are equipped with a switch tube inside. The switching of the switch tube is controlled to realize the switching of the crowbar device 13. Generally, the two crowbar devices 13 have the same effect and can be equivalent to each other. The equivalent relationship is as follows: (1) Among them, R c1 is the resistance value of each crowbar resistor in the three-resistance crowbar device, R c2 is the resistance value of the crowbar resistor in the single resistor crowbar device. According to the equivalent resistance relationship between the single resistor crowbar device and the three resistor crowbar device in formula (1), the resistance value of the single resistor crowbar device can be obtained.

[0037] In one embodiment, the step S110 of connecting the crowbar device to the unit rotor according to a preset strategy includes: Before the unit 10 is accelerated to the grid-connected speed, the crowbar device 13 is always connected to the unit rotor. This can speed up the unit 10 and start it quickly. This method is suitable for scenarios where the heat dissipation performance of the crowbar device 13 is good.

[0038] In one embodiment, the step S110 of connecting the crowbar device to the unit rotor according to a preset strategy includes: Before the unit 10 is accelerated to the grid-connected speed, the crowbar device 13 is intermittently connected to the unit rotor according to a preset period.

[0039] The access period can be freely configured by the user. The system safety can be ensured while taking into account the speed increase of the unit 10. This method is suitable for the scene where the heat dissipation of the crowbar device 13 is general.

[0040] In one embodiment, the step S110 of connecting the crowbar device to the unit rotor according to a preset strategy further includes: The operating parameters of the crowbar device 13 are detected.

[0041] Before the unit 10 is accelerated to the grid-connected speed and the operating parameters are less than the corresponding parameter thresholds, the crowbar device 13 is connected to the rotor of the unit 10 .

[0042] For example, the operating parameters of at least one of the operating current, operating voltage, operating temperature, and unit temperature of the crowbar device 13 may be detected by a related detection circuit.

[0043] In one embodiment, the step S110 of connecting the crowbar device to the unit rotor according to a preset strategy further includes: Before the unit 10 is accelerated to the grid-connected speed and the operating parameter is greater than or equal to the corresponding parameter threshold, the connection between the crowbar device 13 and the rotor of the unit 10 is disconnected.

[0044] Exemplarily, the crowbar device 13 is equipped with a temperature detection sensor, which is intermittently connected according to the working temperature during the startup of the variable speed unit 10. When it is detected that the working temperature exceeds the temperature protection threshold plus the positive hysteresis, the crowbar device 13 is cut off, and when it is detected that the working temperature is lower than the temperature protection threshold minus the negative hysteresis, the crowbar device 13 is connected. The temperature protection threshold, positive hysteresis and negative hysteresis can be freely configured by the user. This method is suitable for occasions where a temperature detection sensor is installed on the crowbar device 13.

[0045] Exemplarily, the crowbar device 13 is equipped with a current detection sensor, which is intermittently connected according to the calculated heat accumulation during the startup of the variable speed unit 10. The heat accumulation formula is: .

[0046] Among them, R c is the equivalent resistance of the crowbar device 13, and i is the working current of the crowbar device 13. When the calculated heat accumulation exceeds the heat protection threshold plus the positive hysteresis, the crowbar device 13 is cut off, and when the calculated heat accumulation is lower than the heat protection threshold minus the negative hysteresis, the crowbar device 13 is connected. The heat protection threshold, positive hysteresis and negative hysteresis can be freely configured by the user. This method is suitable for occasions where a current detection sensor is installed on the crowbar device 13.

[0047] Exemplarily, the crowbar device 13 is equipped with a voltage detection sensor, which is intermittently connected according to the calculated heat accumulation during the startup of the variable speed unit 10. The heat accumulation formula is: .

[0048] Among them, u c is the working voltage at both ends of the crowbar device 13. When the calculated heat accumulation exceeds the heat protection threshold plus the positive hysteresis, the crowbar device 13 is cut off, and when the calculated heat accumulation is lower than the heat protection threshold minus the negative hysteresis, the crowbar device 13 is connected. The heat protection threshold, positive hysteresis and negative hysteresis can be freely configured by the user. This method is suitable for occasions where a voltage detection sensor is installed on the crowbar device 13.

[0049] Exemplarily, the variable speed unit 10 is equipped with a temperature detection sensor, which is intermittently connected according to the unit temperature during the startup process of the variable speed unit 10. When it is detected that the unit temperature exceeds the temperature protection threshold plus the positive hysteresis, the crowbar device 13 is cut off; when it is detected that the unit temperature is lower than the temperature protection threshold minus the negative hysteresis, the crowbar device 13 is connected. The temperature protection threshold, positive hysteresis and negative hysteresis can be freely configured by the user. This method is suitable for occasions where a temperature detection sensor is installed on the variable speed unit 10.

[0050] See also Figure 5 In one embodiment, before step S110, the method further includes: Step S210, determining an actual crowbar resistance value corresponding to a maximum starting torque of a rotor of the unit according to parameters of the unit and parameters of the crowbar device.

[0051] Among them, the parameters of the unit 10, such as the number of pole pairs N of the unit p , stator frequency f s , stator voltage u s , stator reactance X s , rotor reactance X r , slip s, stator resistance R s , stator leakage inductance L s , the converted rotor leakage inductance L' r , stator-rotor mutual inductance l m The parameters of the crowbar device 13, such as the crowbar resistance R c1 , R c2 wait.

[0052] Among them, the expression of the mechanical torque of the unit 10 is first calculated, and then the expression of the starting torque of the unit 10 is obtained according to the expression of the mechanical torque. The equivalent resistance of the crowbar device 13 corresponding to the maximum starting torque is obtained according to the expression of the starting torque. Finally, the equivalent resistance of the crowbar device 13 corresponding to the maximum starting torque is converted to the rotor side to obtain the actual crowbar resistance value corresponding to the maximum starting torque.

[0053] Step S220, obtaining a resistance value range of the crowbar device suitable for the unit in the case of low voltage ride-through, where the resistance value range includes a lower resistance limit value and an upper resistance limit value.

[0054] The low voltage ride-through requirement of the unit 10 is configured according to the unit parameters and application scenarios. For example, the resistance value range of the crowbar device in the low voltage ride-through condition is R cmin ~R cmax , where R cmin is the lower limit of resistance, R cmax is the upper limit of resistance.

[0055] Step S230 , determining the resistance value of the crowbar device according to the resistance value range and the actual crowbar resistance value corresponding to the maximum starting torque.

[0056] For example, the resistance value of the crowbar device 13 can be set within the resistance value range of the crowbar device in the case of low voltage ride-through, so that the crowbar device 13 connected during the start-up of the unit 10 can provide a sufficiently large starting torque to the unit 10, and accelerate the start-up speed without losing step. On the other hand, during the normal operation of the unit 10, when the stator voltage drops, the crowbar device 13 is able to absorb the magnetic field energy to prevent the energy from being fed back to the AC excitation converter 14 and causing system failure.

[0057] In one embodiment, step S230 includes: The actual crowbar resistance value R corresponding to the maximum starting torque c1_maxT <Resistance lower limit R cmin In the case of, the resistance of the crowbar device 13 is the lower resistance limit R cmin .

[0058] The actual crowbar resistance value R corresponding to the maximum starting torque c1_maxT >Resistance upper limit R cmax In the case of, the resistance of the crowbar device 13 is the upper resistance value R cmax .

[0059] At the upper resistance value R cmax ≥The actual crowbar resistance value R corresponding to the maximum starting torque c1_maxT ≥Resistance lower limit R cmin In the case of , the resistance value of the crowbar device 13 is the actual crowbar resistance value corresponding to the maximum starting torque.

[0060] Specifically, the upper resistance value R cmax ≥The actual crowbar resistance value R corresponding to the maximum starting torque c1_maxT ≥Resistance lower limit R cmin In order to obtain the maximum starting torque in the case of , the actual crowbar resistance value can be directly taken as the resistance value of the crowbar device 13. It can be understood that the resistance value of the crowbar device 13 is the equivalent resistance value of the crowbar device 13.

[0061] In one embodiment, step S210 includes: Step A: obtaining the mechanical torque of the unit 10 according to the parameters of the unit 10 and the parameters of the crowbar device 13 .

[0062] The steady-state equivalent circuit diagram of the crowbar device 13 connected to the unit rotor is as follows: Figure 6 As shown, the equivalent circuit of squirrel cage asynchronous motor Figure 1 The rotor resistance is from R' r Increase to R' r +R' c1 , the expression of its mechanical torque is as follows: (2) Among them, R' r is the converted rotor resistance, R' c1 is the equivalent resistance of the crowbar device 13 after conversion.

[0063] Step B: Draw a mechanical characteristic curve of the unit 10 according to the expression of the mechanical torque of the unit 10 to obtain the starting torque of the unit 10.

[0064] According to the mechanical equation, the mechanical characteristic curve is drawn, such as Figure 7 As shown, where s m is the slip corresponding to the maximum torque after the unit rotor is directly short-circuited, s' m is the slip corresponding to the maximum torque after the unit rotor is connected to the crowbar device 13, T m is the maximum torque, T N is the rated torque. Let s = 1, and we can get the expression of starting torque: (3) Among them, X' r is the converted rotor reactance. According to the expression (3) of the starting torque, it can be seen that as the equivalent resistance of the crowbar device 13 increases, the starting torque first increases and then decreases.

[0065] Step C, obtaining the actual crowbar resistance value corresponding to the maximum starting torque of the rotor of the unit 10 according to the starting torque of the unit 10.

[0066] The expression (3) of the starting torque is the equivalent resistance of the crowbar device 13 R' c1 By taking the derivative and making it equal to 0, the equivalent resistance of the crowbar device 13 corresponding to the maximum starting torque can be obtained.

[0067] (4) The equivalent resistance of the crowbar device 13 corresponding to the maximum starting torque is converted to the rotor side to obtain the actual crowbar resistance corresponding to the maximum starting torque.

[0068] (5) Among them, N sr is the stator-rotor turns ratio.

[0069] In some embodiments, the startup method further comprises the following steps: Step S310, in response to the speed of the unit 10 increasing to the grid-connected speed, the crowbar device 13 is controlled to be disconnected from the unit rotor.

[0070] Step S320, controlling the excitation converter 14 to excite the rotor of the unit, connecting the stator of the unit and the secondary side of the isolation transformer 11 to complete the grid connection.

[0071] Specifically, the drive makes the stator working voltage of the unit synchronize with the amplitude, frequency and phase of the AC working voltage of the power grid, refer to Figure 1 , control the first circuit breaker QF1 to close, the second circuit breaker QF2, the third circuit breaker QF3, and the fourth circuit breaker QF4 to open, and connect the stator of the unit and the secondary side of the isolation transformer 11; at the same time, the second circuit breaker QF2K2 and the fourth circuit breaker QF4K4 can be turned off, and the grid connection process is completed.

[0072] Step S330, entering the water pumping control phase.

[0073] That is, the excitation converter 14 enters the normal vector control of the unit 10. 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, which can absorb the AC active power of the power grid for pumped storage and send reactive power to the AC power grid.

[0074] See also Figure 8 The embodiment of the present application also provides a variable speed pumped storage unit starting device, comprising: The control unit 81 is used to respond to the pumping start command of the unit 10 and connect the crowbar device 13 to the rotor of the unit 10 according to a preset strategy, so that the unit 10 is equivalent to a squirrel cage asynchronous motor; The driving unit 82 is used to connect the driving power supply device to drive the stator of the unit 10 to increase the speed of the unit 10 to the grid-connected speed.

[0075] The specific implementation manner and beneficial effects of the variable speed pumped storage unit starting device can refer to the description of the implementation manner of the above-mentioned variable speed pumped storage unit starting method, which will not be repeated here.

[0076] See also Figure 1 and Fig. 9In a third aspect, an embodiment of the present application further provides an electric power device 90, comprising an isolation transformer 11, an excitation transformer 12, a controller 91, a memory 92, and a computer program 921 stored in the memory 92 and executable on the controller 91, as well as a crowbar device 13, a first circuit breaker QF1, a second circuit breaker QF2, a third circuit breaker QF3, a fourth circuit breaker QF4, an excitation converter 14, and a frequency converter 15 respectively connected to the controller 91, a first end of the first circuit breaker QF1, a first end of the second circuit breaker QF2, and a first end of the excitation transformer 12 are connected in common and connected to the power grid AC through the isolation transformer 11, and a second end of the first circuit breaker QF1 is connected to the power grid AC. The variable speed pumped storage unit 10 is connected to the unit stator, the second end of the second circuit breaker QF2 is connected to the first end of the frequency converter 15, the second end of the frequency converter 15 is connected to the unit stator through the third circuit breaker QF3, the first end of the excitation converter 14 is connected to the second end of the isolation transformer 11 through the excitation transformer 12, the second end of the excitation converter 14 is connected to the unit rotor of the variable speed pumped storage unit 10, the crowbar device 13 is connected to the rotor of the unit 10, the first end of the fourth circuit breaker QF4 is connected to the drive unit 20, the second end of the fourth circuit breaker QF4 is connected to the unit stator, and the controller 91 implements the steps of the variable speed pumped storage unit starting method in any of the above embodiments when executing the computer program 921.

[0077] Those skilled in the art will understand that Fig. 9 This is merely an example of the power device 90 and does not constitute a limitation on the power device 90 . The power device 90 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.

[0078] The controller 91 may be a central processing unit (CPU), or other general controllers 91, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general controller 91 may be a microcontroller 91 or any conventional controller 91.

[0079] In some embodiments, the memory 92 may be an internal storage unit of the power device 90, such as a hard disk or memory of the power device 90. In other embodiments, the memory 92 may also be an external storage device of the power device 90, 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 90. Further, the memory 92 may also include both an internal storage unit of the power device 90 and an external storage device. The memory 92 is used to store an operating system, an application program, a boot loader, data, and other programs. The memory 92 may also be used to temporarily store data that has been output or is to be output.

[0080] The embodiment of the present application further provides a computer-readable storage medium, which stores a computer program 921 , and when the computer program 921 is executed by the controller 91 , the steps in the above-mentioned method embodiments can be implemented.

[0081] The embodiment of the present application provides a computer program 921 product, which, when executed on a computer, enables the computer to execute the steps in the above-mentioned various method embodiments.

[0082] 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 921. The computer program 921 can be stored in a computer-readable storage medium. When the computer program 921 is executed by the controller 91, the steps of the above method embodiments can be implemented. Among them, the computer program 921 includes a computer program 921 code, and the computer program 921 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 921 code to the camera device / terminal device, a recording medium, a computer memory 92, a ROM (Read-Only Memory, read-only memory 92), a RAM (Random Access Memory, random access memory 92), 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.

[0083] 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 921 product. The computer program 921 product includes one or more computer instructions. The computer instructions can be stored in the above-mentioned computer readable storage medium.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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 a pumping start command of the unit, a crowbar device is connected to the rotor of the unit according to a preset strategy, so that the unit is equivalent to a squirrel cage asynchronous motor; 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: The method of connecting the crowbar device to the unit rotor according to a preset strategy includes: Before the unit is accelerated to the grid-connected speed, the crowbar device is always connected to the unit rotor; or Before the unit is accelerated to the grid-connected speed, the crowbar device is intermittently connected to the unit rotor according to a preset period.

3. The startup method according to claim 1, characterized in that: The method of connecting the crowbar device to the unit rotor according to a preset strategy also includes: Detecting operating parameters of the crowbar device; Before the unit is accelerated to the grid-connected speed and when the operating parameter is less than the corresponding parameter threshold, the crowbar device is connected to the unit rotor.

4. The startup method according to claim 3, characterized in that: The connecting the crowbar device to the unit rotor according to a preset strategy also includes: Before the unit speed increases to the grid-connected speed and when the operating parameter is greater than or equal to the corresponding parameter threshold, the connection between the crowbar device and the unit rotor is disconnected.

5. The starting method according to claim 3 or 4, characterized in that: The operating parameters include at least one of the operating current, operating voltage, operating temperature and unit temperature of the crowbar device.

6. The starting method according to any one of claims 1 to 4, characterized in that: Before the crowbar device is connected to the rotor of the unit according to a preset strategy in response to the unit pumping start command, the method includes: Determine an actual crowbar resistance value corresponding to the maximum starting torque of the rotor of the unit according to the parameters of the unit and the parameters of the crowbar device; Obtaining a resistance value range of the crowbar device applicable to the unit in a low voltage ride-through condition, wherein the resistance value range includes a lower resistance limit value and an upper resistance limit value; The resistance value of the crowbar device is determined according to the resistance value range and the actual crowbar resistance value corresponding to the maximum starting torque.

7. The startup method according to claim 6, characterized in that: The determining the resistance value of the crowbar device according to the resistance value range and the actual crowbar resistance corresponding to the maximum starting torque includes: When the actual crowbar resistance value corresponding to the maximum starting torque is less than the resistance lower limit value, the resistance value of the crowbar device is equal to the resistance lower limit value; When the actual crowbar resistance value corresponding to the maximum starting torque is greater than the resistance upper limit value, the resistance value of the crowbar device is equal to the resistance upper limit value; When the upper resistance limit is not less than the actual crowbar resistance value corresponding to the maximum starting torque, and the actual crowbar resistance value corresponding to the maximum starting torque is not less than the lower resistance limit, the resistance value of the crowbar device is the actual crowbar resistance value corresponding to the maximum starting torque.

8. The startup method according to claim 6, characterized in that: The determining, according to the parameters of the unit and the parameters of the crowbar device, an actual crowbar resistance value corresponding to the maximum starting torque of the unit rotor comprises: Obtaining the mechanical torque of the unit according to the parameters of the unit and the parameters of the crowbar device; Draw a mechanical characteristic curve of the unit according to the expression of the mechanical torque of the unit to obtain the starting torque of the unit; The actual crowbar resistance value corresponding to the maximum starting torque of the rotor of the unit is obtained according to the starting torque of the unit.

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 connecting the crowbar device to the rotor of the unit according to a preset strategy, so that the unit is equivalent to a squirrel cage asynchronous motor; 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 an isolation transformer, an excitation transformer, a controller, a memory, and a computer program stored in the memory and executable on the controller, as well as a crowbar device, a first circuit breaker, a second circuit breaker, a third circuit breaker, a fourth circuit breaker, an excitation converter 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 excitation transformer are connected together and connected to the power grid through the isolation transformer, the second end of the first circuit breaker is connected to the stator of the variable speed pumped storage unit, and the second end of the second circuit breaker is connected to the transformer. The first end of the frequency converter is connected to the stator of the unit through the third circuit breaker, the first end of the excitation converter is connected to the second end of the isolation transformer through the excitation transformer, the second end of the excitation converter is connected to the unit rotor of the variable speed pumped storage unit, the crowbar device is connected to the unit rotor, the first end of the fourth circuit breaker is connected to the drive unit, and the second end of the fourth circuit breaker is connected to the unit stator. When the controller executes the computer program, the steps of the variable speed pumped storage unit starting method as described in any one of claims 1 to 8 are implemented.

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