Flywheel energy storage control method, system and equipment and storage medium

Abstract

The invention discloses a flywheel energy storage control method, system and device and a storage medium, and is applied to the technical field of magnetic suspension flywheels, and the method comprises the steps: when a flywheel is in a static state and the charging work of the flywheel is started, controlling a machine side converter according to a principle that the rotation acceleration of the flywheel remains unchanged, the rotating speed of the flywheel is increased from zero to the minimum working speed nmin; when the rotating speed of the flywheel is within the range from nmin to the switching speed ns, the machine-side converter is controlled according to the principle that the output current of the machine-side converter is kept unchanged so as to charge or discharge the flywheel; and when the rotating speed of the flywheel is within the range from the switching speed ns to the maximum speed nmax, controlling the machine-side converter according to the principle that the output power of the machine-side converter is kept unchanged so as to charge or discharge the flywheel. By applying the scheme of the invention, the control of flywheel energy storage can be effectively realized, the charging and discharging efficiency is ensured, and the stability during charging and discharging and the power supply quality are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic levitation flywheels, and in particular to a control method, system, device and storage medium for flywheel energy storage. Background Art

[0002] In special occasions such as photovoltaic / wind power plants and mountainous areas, where photovoltaic / wind power generation and city power supply are unstable, UPS (Uninterruptible Power Supply) devices and diesel generators are used for auxiliary power supply. Diesel generators are noisy when supplying power. Most UPS devices use chemical batteries as energy storage elements, which have disadvantages such as low efficiency and high failure rate. Magnetic levitation flywheel energy storage technology is a new type of green and environmentally friendly mechanical energy storage technology, which has many advantages such as rapid discharge, high energy storage density, high efficiency, high power, long life, and low noise. It has gradually been applied to power system peak regulation, brake energy recovery, auxiliary power supply, electromagnetic catapult and other fields.

[0003] When the flywheel is storing energy (charging condition), the electric energy can drive the motor after passing through the power converter, and then the motor drives the flywheel to accelerate. At this time, the flywheel stores energy in the form of kinetic energy, completing the energy storage process of converting electric energy to mechanical energy. When receiving the control signal of energy release, the flywheel will release energy (discharging condition), and the high-speed rotating flywheel will drive the motor to generate electricity, and the power converter will output the current and voltage suitable for the load, or feedback to the power grid, completing the energy release process of converting mechanical energy to electric energy.

[0004] The traditional flywheel energy storage charging and discharging control process is very simple, usually based on a double closed-loop structure of vector control, with simple control based on speed. Taking the charging process as an example, a maximum speed is directly given, so that the flywheel speed is pulled up to the maximum speed to complete the flywheel charging, and the stability of voltage and current is poor. Similarly, when discharging, the flywheel speed is directly controlled to be reduced with low speed as the target, and the power fluctuation is often large and cannot meet user needs well.

[0005] In summary, how to effectively control flywheel energy storage and improve the charge and discharge performance of the flywheel is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] The purpose of the present invention is to provide a control method, system, device and storage medium for flywheel energy storage, so as to effectively realize the control of flywheel energy storage and improve the charge and discharge performance of the flywheel.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a control method for flywheel energy storage, wherein the flywheel energy storage device comprises: a grid-side converter, a machine-side converter and a motor connected in sequence; a flywheel matched with the motor, used to control a grid-side controller of the grid-side converter, and used to control a machine-side controller of the machine-side converter; the control method for flywheel energy storage is applied to the machine-side controller, comprising:

[0009] When the flywheel is in a stationary state and the charging operation of the flywheel is started, the generator-side converter is controlled according to the principle that the rotational acceleration of the flywheel remains unchanged, so that the speed of the flywheel increases from zero to a preset minimum operating speed n min ;

[0010] When the speed of the flywheel is at the minimum operating speed n min To the preset switching speed n s When the output current of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged, so as to charge or discharge the flywheel;

[0011] When the speed of the flywheel is at the switching speed n s To the preset maximum speed n max When the output power of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output power of the machine-side converter remains unchanged, so as to charge or discharge the flywheel;

[0012] Among them, the maximum speed n max >The switching speed n s >The minimum operating speed n min >0.

[0013] In one embodiment, the control system used by the machine-side controller is a double closed-loop feedback control system;

[0014] The machine-side converter is controlled according to the principle that the rotational acceleration of the flywheel remains unchanged, so that the speed of the flywheel increases from zero to a preset minimum operating speed n min ,include:

[0015] Set the current speed to the given value n ref As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ;

[0016] Based on the dual closed-loop feedback control system, the generator-side converter is controlled so that the speed of the flywheel increases from zero to a preset minimum operating speed n min ;

[0017] Wherein, when the speed of the flywheel increases from zero to the minimum working speed n min During the process, the speed given value n ref The value of increases from the set initial value to the minimum working speed n according to a fixed step size. min .

[0018] In one embodiment, the control system used by the machine-side controller is a double closed-loop feedback control system;

[0019] The machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged to charge or discharge the flywheel, including:

[0020] Under charging conditions, the first voltage is set to a value V ref1 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [0, i q _ lim ] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ;

[0021] Under the discharge condition, the second voltage is set to V ref2 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [-i q _ lim , 0] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ;

[0022] Controlling the machine-side converter based on the dual closed-loop feedback control system to charge or discharge the flywheel;

[0023] Among them, V ref1 =U ref +a,V ref2 =U ref -b,U refis the bus voltage given value used by the grid-side controller to control the grid-side converter, a and b are both set to values ​​greater than 0, i q _ lim is the preset first limit value and i q _ lim Greater than 0.

[0024] In one embodiment, the control system used by the machine-side controller is a double closed-loop feedback control system;

[0025] The machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged to charge or discharge the flywheel, including:

[0026] Under charging conditions, the first power given value P ref1 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [0, i pow _ lim ] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ;

[0027] Under the discharge condition, the second power given value P ref2 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [-i pow _ lim , 0] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ;

[0028] Controlling the machine-side converter based on the dual closed-loop feedback control system to charge or discharge the flywheel;

[0029] Among them, the first power given value P ref1 Greater than 0, the second power setting value P ref1 Less than 0, i pow _ lim is the preset second limit value and i pow _ lim Greater than 0.

[0030] In one embodiment, it further includes:

[0031] When the speed of the flywheel is greater than or equal to the maximum speed nmax When the speed of the flywheel is maintained at the maximum speed n max The machine-side converter is controlled according to the principle of.

[0032] In one embodiment, the control system used by the machine-side controller is a double closed-loop feedback control system;

[0033] When the speed of the flywheel is greater than or equal to the maximum speed n max When the speed of the flywheel is maintained at the maximum speed n max The principle of controlling the machine-side converter includes:

[0034] When the speed of the flywheel is greater than or equal to the maximum speed n max When the maximum speed n max As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ;

[0035] Based on the dual closed-loop feedback control system, the generator-side converter is controlled so that the speed of the flywheel is maintained at the maximum speed n max .

[0036] In one embodiment, the control system used by the machine-side controller is a double closed-loop feedback control system; the flywheel energy storage control method further includes:

[0037] After the flywheel shutdown operation is started, when the speed of the flywheel is greater than or equal to the switching speed n s When the third power given value P ref3 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [-i pow _ lim , 0] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ; Based on the dual closed-loop feedback control system, the machine-side converter is controlled to reduce the rotational speed of the flywheel;

[0038] When the speed of the flywheel is less than the switching speed n s When 0 is used as the outer loop q-axis target value of the dual closed-loop feedback control system, the current speed feedback value n fedAs the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ; Based on the dual closed-loop feedback control system, the machine-side converter is controlled until the speed of the flywheel is reduced to 0;

[0039] Among them, the third power given value P ref3 Less than 0, i pow _ lim is the preset second limit value and i pow _ lim Greater than 0.

[0040] In one embodiment, it further includes:

[0041] When the speed of the flywheel is higher than the minimum operating speed n min , when the grid-side converter fails and the generator-side converter is normal, the generator-side converter is controlled according to the principle of maintaining the bus voltage unchanged to charge or discharge the flywheel;

[0042] In one embodiment, the control system used by the machine-side controller is a double closed-loop feedback control system;

[0043] When the speed of the flywheel is higher than the minimum operating speed n min , when the grid-side converter fails and the generator-side converter is normal, controlling the generator-side converter according to the principle of maintaining the bus voltage unchanged to charge or discharge the flywheel, including:

[0044] The third voltage is set to a fixed value V ref3 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [-i q _ max ,i q _ max ] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ;

[0045] Controlling the machine-side converter based on the dual closed-loop feedback control system to charge or discharge the flywheel;

[0046] Among them, i q _ max is the preset third limit value and i q _ max Greater than 0.

[0047] In a second aspect, the present invention provides a control system for flywheel energy storage, wherein the flywheel energy storage device comprises: a grid-side converter, a machine-side converter and a motor connected in sequence; a flywheel matched with the motor, a grid-side controller for controlling the grid-side converter, and a machine-side controller for controlling the machine-side converter; the control system for flywheel energy storage comprises:

[0048] A speed mode control unit is used to control the generator-side converter according to the principle that the acceleration of the flywheel rotation remains unchanged when the flywheel is in a stationary state and the charging operation of the flywheel is started, so that the speed of the flywheel increases from zero to a preset minimum operating speed n min ;

[0049] A constant current mode control unit is used to control the flywheel speed when the flywheel speed is at the minimum operating speed n min To the preset switching speed n s When the output current of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged, so as to charge or discharge the flywheel;

[0050] The constant power mode control unit is used for switching the flywheel speed to the switching speed n when the flywheel speed is at the switching speed n s To the preset maximum speed n max When the output power of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output power of the machine-side converter remains unchanged, so as to charge or discharge the flywheel;

[0051] Among them, the maximum speed n max >The switching speed n s >The minimum operating speed n min >0.

[0052] In a third aspect, the present invention provides a control device for flywheel energy storage, comprising:

[0053] Memory for storing computer programs;

[0054] A processor is used to execute the computer program to implement the steps of the flywheel energy storage control method as described above.

[0055] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the flywheel energy storage control method as described above are implemented.

[0056] Applying the technical solution provided by the embodiment of the present invention, when the flywheel is in a stationary state and the rotation speed reaches the maximum speed n maxIn the speed range, three different modes are divided to ensure the stability during charging and discharging. Specifically, the flywheel energy storage device includes a grid-side converter, a machine-side converter and a motor connected in sequence; a flywheel matched with the motor, a grid-side controller for controlling the grid-side converter, and a machine-side controller for controlling the machine-side converter. The control method of flywheel energy storage can be applied to the machine-side controller.

[0057] When the flywheel is stationary and the charging operation of the flywheel is started, the machine-side converter is controlled according to the principle that the acceleration of the flywheel rotation remains unchanged, so that the speed of the flywheel increases from zero to the preset minimum operating speed n min This mode is the speed mode. It is designed to take into account that the flywheel speed is low and cannot provide enough power. Therefore, charging can be performed, but it cannot effectively power the load. In addition, charging in the speed mode keeps the acceleration of the flywheel rotation constant, which can ensure the stability of the voltage and current, and the torque will be very stable, so that the flywheel speed can be stably increased from zero to the minimum working speed n. min .

[0058] When the flywheel speed is at the minimum working speed n min To the preset switching speed n s When it is within the range of , it is the constant current mode. At this time, the flywheel can provide a certain degree of electrical energy, so the flywheel can be charged or discharged. In this mode, the flywheel speed is not high enough to ensure stable power output. Therefore, the machine-side converter will be controlled according to the principle of keeping the output current of the machine-side converter unchanged, which can effectively ensure the output current stability of the machine-side converter and ensure the charging and discharging efficiency.

[0059] When the flywheel speed is at the switching speed n s To the preset maximum speed n max When it is within the range, it is the constant power mode, which is also the main working mode of the flywheel. In this mode, the machine-side converter will be controlled according to the principle that the output power of the machine-side converter remains unchanged to charge or discharge the flywheel, thus ensuring the charging and discharging stability of the flywheel and the power supply quality.

[0060] It can also be seen that when the present application scheme switches between different modes, the current speed of the flywheel can be used to determine which mode to switch to. The mode switching and charging and discharging switching are flexible and convenient, and can be switched online in real time. In summary, the present application scheme can effectively realize the control of flywheel energy storage. By selecting the appropriate mode, the charging and discharging efficiency is guaranteed, and the stability and power supply quality during charging and discharging are guaranteed, which is conducive to achieving the optimal control effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0062] Figure 1 It is a structural schematic diagram of a flywheel energy storage device in a specific embodiment of the present invention;

[0063] Figure 2 It is a structural schematic diagram of a grid-side converter and a generator-side converter in a specific implementation manner of the present invention;

[0064] Figure 3 It is a structural schematic diagram of a flywheel energy storage device in another specific embodiment of the present invention;

[0065] Figure 4 A flowchart of a flywheel energy storage control method provided in a specific embodiment of the present invention;

[0066] Figure 5 It is a schematic diagram of the changes of the flywheel speed, the motor torque, and the motor output power in different modes in a specific embodiment of the present invention;

[0067] Figure 6 It is a schematic diagram of the principle of a dual closed-loop feedback control system supporting switching between different modes in a specific implementation manner of the present invention;

[0068] Figure 7 It is a schematic diagram of the control principle of a double closed-loop feedback control system used in controlling a generator-side converter in a specific implementation manner of the present invention.

[0069] Figure 8 This is a schematic diagram of the principle of a constant current mode in a specific implementation mode of the present invention;

[0070] Fig. 9 A schematic diagram of the principle of a constant power mode in a specific implementation manner of the present invention;

[0071] Fig.10 A schematic diagram of the structure of a flywheel energy storage control system provided in a specific embodiment of the present invention;

[0072] Fig.11 A schematic diagram of the structure of a flywheel energy storage control device provided in a specific embodiment of the present invention;

[0073] Fig.12 This is a flow chart of an implementation of a flywheel energy storage control method provided in another specific embodiment of the present invention. DETAILED DESCRIPTION

[0074] The core of the present invention is to provide a control method for flywheel energy storage. When switching between different modes, the mode to switch to can be determined based on the current speed of the flywheel. The mode switching and charging and discharging switching are flexible and convenient, and can be switched online in real time. In summary, the present application scheme can effectively realize the control of flywheel energy storage. By selecting a suitable mode, the charging and discharging efficiency is guaranteed, and the stability and power supply quality during charging and discharging are guaranteed, which is conducive to achieving the optimal control effect.

[0075] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0076] See also Figure 1 , is a schematic diagram of the structure of a flywheel energy storage device in a specific embodiment of the present invention. The flywheel energy storage device includes a grid-side converter, a machine-side converter and a motor connected in sequence; a flywheel matched with the motor, a grid-side controller for controlling the grid-side converter, and a machine-side controller for controlling the machine-side converter.

[0077] The source of AC power on the grid side can be mains electricity, diesel generators, AC UPS, etc., which can directly supply power to AC loads. When the flywheel is charged by AC power on the grid side, the grid-side converter is used as a rectifier and the machine-side converter is used as an inverter. There is a DC bus between the grid-side converter and the machine-side converter, which can supply power to DC loads. Figure 2 , is a schematic diagram of the structure of a grid-side converter and a generator-side converter in a specific implementation manner of the present invention, Figure 2 The grid-side converter and the machine-side converter in the system both adopt a three-phase full-bridge structure. Figure 2 As shown, the grid-side converter is connected to the AC input (R / S / T) and is controlled by the grid-side controller. Figure 2 The grid-side controller in the system includes a grid-side control unit and a grid-side drive unit. The machine-side converter is connected to the motor to output three-phase power (U / V / W), which is controlled by the machine-side controller. Figure 2 The machine side controller includes a machine side control unit and a machine side drive unit. A voltage stabilizing capacitor C and a current limiting resistor R are also shown at the DC bus. The motor in the present application supports asynchronous motors and synchronous motors.

[0078] Depend on Figure 1It can be seen that when the mains or diesel generator is connected, on the one hand, it can directly supply power to the AC power load, and on the other hand, it can store energy for the flywheel through the power converter (grid-side converter and machine-side converter), and the electrical energy is converted into mechanical energy and stored in the flywheel. When the flywheel needs to release energy, such as when the mains is off, the mechanical energy of the flywheel will be converted into electrical energy to continuously supply power to the AC and DC power loads. If the UPS is connected at this time, the flywheel system can also charge the UPS.

[0079] In addition, the flywheel energy storage device can support the parallel use of multiple machine-side converters. Figure 3 , is a schematic diagram of the structure of a flywheel energy storage device in another specific implementation manner, Figure 3 In the embodiment, the machine-side converter 1 and the machine-side converter 2 are used in parallel, and the flywheel 1 and the flywheel 2 are connected through the motor 1 and the motor 2, respectively. In other embodiments, more parallel numbers can be used as needed. In the following text, the control of a single machine-side converter is used as an example for explanation. If multiple machine-side converters are required to operate in parallel, it is generally only necessary to set the same current limit, voltage, and power setting values ​​in each mode to achieve the effect of synchronous control. Each machine-side converter can be configured with a bus interface to connect to the PLC, and the PLC sends instructions to ensure the consistency of start and stop of each parallel machine-side converter.

[0080] It can be seen that in the present application, the requirements for the flywheel energy storage device are relatively low, and a more general machine-side converter + grid-side converter structure can be adopted. The motor supports both asynchronous motors and synchronous motors, and supports the use of a single machine-side converter and the use of multiple machine-side converters in parallel, making the present application highly versatile.

[0081] Please refer to Figure 4 , Figure 4 The present invention provides a specific implementation method of a flywheel energy storage control method. The flywheel energy storage control method can be applied to a machine-side controller, and includes the following steps:

[0082] Step S101: When the flywheel is in a stationary state and the charging operation of the flywheel is started, the generator-side converter is controlled according to the principle that the acceleration of the flywheel rotation remains unchanged, so that the speed of the flywheel increases from zero to a preset minimum operating speed n min .

[0083] Specifically, the speed of the flywheel is between zero and the minimum operating speed n min When the speed is within the range of , the machine-side controller of the present application scheme will control the machine-side converter according to the speed mode. At this time, the flywheel speed is low and cannot provide enough power, so it can be charged, but it cannot power the load.

[0084] Whether the flywheel is in a charging condition or a discharging condition can usually be determined by the user. For example, the user can determine whether the flywheel is currently in a charging condition or a discharging condition by operating a related button / switch. Of course, in some other occasions, the current condition of the flywheel can be automatically determined according to a preset program.

[0085] When the flywheel is stationary and the charging operation of the flywheel is started, it means that the flywheel has entered the charging state from the stationary state. The machine-side controller will control the machine-side converter according to the speed mode, so that the speed of the flywheel increases from zero to the minimum working speed n. min During the process, the rotational acceleration of the flywheel remains unchanged, that is, the speed of the flywheel starts from zero and increases to the minimum working speed n at a stable slope. min This will not only ensure the stability of voltage and current, but also the torque will be very stable. Figure 5 , which is a schematic diagram of the changes in flywheel speed, motor torque, and motor output power in different modes in a specific implementation mode of the present invention. It can be seen that in the speed mode, the motor torque is small and very stable, and the flywheel speed and motor output power are increasing evenly.

[0086] There are many specific implementation methods for keeping the flywheel rotation acceleration constant. For example, in a specific implementation of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system; step S101 describes controlling the machine-side converter according to the principle of keeping the flywheel rotation acceleration constant, so that the speed of the flywheel increases from zero to a preset minimum operating speed n. min , which may specifically include:

[0087] Set the current speed to the given value n ref As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ;

[0088] Based on the double closed-loop feedback control system, the machine-side converter is controlled so that the speed of the flywheel increases from zero to the preset minimum operating speed n min ;

[0089] Among them, when the speed of the flywheel increases from zero to the minimum working speed n min In the process, the speed setting value n ref The value of increases from the set initial value to the minimum working speed n according to a fixed step size. min .

[0090] This embodiment takes into account that if the speed given value n is directlyref Set to minimum operating speed n min , although it can also gradually increase the flywheel speed to the minimum working speed n min , but the fluctuation of the flywheel speed may be large during the process. In this implementation, the speed given value n ref The value of is based on a fixed step length, rising from the set initial value to the minimum working speed n min , which is equivalent to the range from 0 to the minimum working speed n min Multiple speed values ​​are evenly divided between them, and these speed values ​​are used as speed given values ​​n one by one ref , which can make the speed feedback value n fed Effectively track the speed setpoint n ref , and the speed feedback value n fed The rising process will be very stable, that is, it can rise at a relatively stable acceleration, achieving the purpose of keeping the flywheel rotation acceleration unchanged in the present application scheme.

[0091] Since the dual closed-loop feedback control system is more convenient, the control system used by the machine-side controller in this implementation is a dual closed-loop feedback control system. In addition, in practical applications, the grid-side controller and the machine-side controller usually use a dual closed-loop feedback control system with decoupling, for example, both are dual closed-loop PI control with decoupling, and the modulation method in the dual closed-loop feedback control system can usually use SVPWM (Space Vector Pulse Width Modulation).

[0092] In practical applications, for the dual closed-loop feedback control of the grid-side converter, the voltage outer loop can use a PI controller, the current inner loop can also use a PI controller, dq current decoupling, grid voltage feedforward, and SVPWM modulation. The grid-side controller can always control the grid-side converter based on the voltage mode, that is, using Uref as the control target of the bus voltage (the output voltage of the grid-side converter), so that the bus voltage feedback value V fed Of course, in other specific occasions, other specific forms can be used to implement the grid-side converter control, which does not affect the implementation of the present invention.

[0093] See also Figure 6 , which is a schematic diagram of the principle of a dual closed-loop feedback control system supporting switching between different modes, Figure 6 In speed mode, the current speed is set to n. ref As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fedAs the outer loop q-axis feedback, the error between the two is obtained and then input into the PI controller. The output of the PI controller is the outer loop q-axis output generated by feedback control in speed mode, and the outer loop q-axis output needs to be used as the q-axis current target used by the dual closed-loop feedback control system, recorded as .

[0094] The q-axis current target value is obtained After that, the subsequent data processing flow based on the double closed-loop feedback control system can be continued to finally realize the control of the machine-side converter. Figure 6 , can be based on the q-axis current target and q-axis current feedback i sq The error is calculated and input into the PI controller of the current inner loop, based on the d-axis current target value and d-axis current feedback i sd The error is calculated and input into the PI controller of the current inner loop to realize the control of the machine-side converter. Figure 6 In the example, the dual closed-loop feedback control system uses SVPWM modulation. In addition, Figure 6 In the embodiment, the outer ring d-axis target value is determined by the weak magnetic control process. When the weak magnetic control is adopted, the speed of the flywheel can be allowed to rise higher. In other embodiments, other methods may be used to determine the outer ring d-axis target value. That is to say, for the q-axis current target value in the double closed-loop feedback control system This application does not limit other aspects, as long as they can effectively realize the control of the machine-side converter. Figure 7 Schematic diagram of the control principle of a double closed-loop feedback control system used in controlling the generator-side converter in a specific implementation mode, wherein the speed feedback value n fed It can be obtained based on flux observation or directly through an encoder. The outer loop of the dual closed-loop feedback control system adopts a PI controller, the current inner loop adopts a PI controller, dq current decoupling, voltage feedforward, and SVPWM modulation.

[0095] Step S102: When the speed of the flywheel is at the minimum working speed n min To the preset switching speed n s When the output current of the machine-side converter remains unchanged, the machine-side converter is controlled to charge or discharge the flywheel.

[0096] When the flywheel speed is at the minimum working speed n min To switching speed n sWhen the current is within the range of , it is in constant current mode. At this time, the flywheel can charge and discharge normally, but under certain current limits, stable power output cannot be guaranteed. In addition, since the machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged, the output current stability of the machine-side converter can be effectively guaranteed, and the charging and discharging efficiency can be guaranteed. Figure 5 ,It can be seen that in constant current mode, when charging, the motor torque will increase, the flywheel speed and the motor output power will increase rapidly and steadily.

[0097] It can be seen that when switching from the speed mode above to the constant current mode at this time, the trigger condition is that the speed of the flywheel is less than the minimum working speed n min It rose to n min to n s In the range of min to n s Within the range, reduce to less than the minimum operating speed n min , it will switch back from constant current mode to speed mode. Similarly, for the constant power mode and hold mode described later, when the present application switches between different modes, the mode to be switched to can be determined based on the current speed of the flywheel. The mode switching is flexible and convenient, and can be switched online in real time.

[0098] There may be multiple specific implementations for keeping the output current of the machine-side converter constant. For example, in a specific implementation of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system. The control of the machine-side converter according to the principle that the output current of the machine-side converter remains constant to charge or discharge the flywheel described in step S102 may specifically include:

[0099] Under charging conditions, the first voltage is set to a value V ref1 As the outer loop q-axis target value of the double closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [0, i q _ lim ] is limited, and the result is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system. ;

[0100] Under the discharge condition, the second voltage is set to V ref2 As the outer loop q-axis target value of the double closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [-i q _lim , 0] is limited, and the result is used as the q-axis current target quantity currently used by the double closed-loop feedback control system. ;

[0101] Based on the double closed-loop feedback control system, the machine-side converter is controlled to charge or discharge the flywheel;

[0102] Among them, V ref1 =U ref +a,V ref2 =U ref -b,U ref is the bus voltage reference value used by the grid-side controller to control the grid-side converter. a and b are both set to values ​​greater than 0. q _ lim is the preset first limit value and i q _ lim Greater than 0.

[0103] In this embodiment, the outer loop q-axis target value of the dual closed-loop feedback control system is the voltage given value V ref , and during charging and discharging, V ref Taking charging as an example, in order to achieve the effect of accelerated charging, the first voltage given value V ref1 As the outer loop q-axis target value of the double closed-loop feedback control system, V ref1 =U ref +a, a is a value greater than 0, that is, the first voltage given value V ref1 is the bus voltage given value U ref On the basis of , some values ​​are added to make the bus voltage setting on the inverter side higher than the bus voltage setting on the rectifier side. Therefore, the voltage loop of the machine-side converter will work in the positive limit state, which can realize continuous charging of the flywheel and ensure charging efficiency. Figure 8 , is a schematic diagram of the principle of a constant current mode in a specific implementation. In order to ensure constant current, the first voltage is set to a given value V ref1 As the outer loop q-axis target value of the double closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback, the error between the two is obtained and input into the PI controller, so that the outer loop q-axis output can be generated through feedback control. At this time, the outer loop q-axis output needs to be controlled through the range [0, i q _ lim ] is limited, and the result obtained will be used as the q-axis current target quantity currently used by the dual closed-loop feedback control system .

[0104] That is, if the outer ring q-axis output is higher than i q _lim , then after limiting, the q-axis current target That is i q _ lim If the outer loop q-axis output is less than 0, then after limiting, the q-axis current target It is 0, and the q-axis current target value will not appear Beyond [0, i q _ lim ] situation. It is understandable that due to V ref1 =U ref +a, so that the voltage loop works at the positive limit state during charging, so generally speaking, the outer loop q-axis output is usually higher than i q _ lim , and then through the range [0, i q _ lim ], the q-axis current target value will be Stable equals i q _ lim , thus achieving the purpose of constant current.

[0105] The discharge process is the same. Since the current direction is opposite, the range used is [-i q _ lim , 0], so that during discharge, the q-axis current target Stable equals -i q _ lim , thus achieving the purpose of constant current. V ref2 =U ref -b, that is, during discharge, the second voltage given value V ref2 is the bus voltage given value U ref On the basis of , some values ​​are lowered so that the bus voltage setting on the inverter side will be lower than the bus on the rectifier side. Therefore, the voltage loop of the machine-side converter will work in the negative limit state, which can realize continuous discharge of the flywheel and ensure discharge efficiency.

[0106] In this embodiment, the same control architecture is used for the charging and discharging conditions in the constant current mode to generate the required q-axis current target value. , but when charging and discharging, the voltage used is the given value V ref Different, and different range restrictions, that is, there is no need to set up completely different dual closed-loop feedback control systems for the charging condition and the discharging condition in the constant current mode, which improves the versatility of the present application scheme.

[0107] Step S103: When the speed of the flywheel is at the switching speed n s To the preset maximum speed n maxWhen it is within the range of , the machine-side converter is controlled according to the principle that the output power of the machine-side converter remains unchanged to charge or discharge the flywheel.

[0108] It is understandable that the maximum speed n max >Switching speed n s >Minimum working speed n min > 0. Maximum speed n max and minimum operating speed n min Usually depends on the flywheel hardware structure, the switching speed n s You can follow n s = (9.55 × P) / T, where P represents the set constant power charging value, and T represents the set maximum charging torque limit value.

[0109] When the flywheel speed is at the switching speed n s To the preset maximum speed n max When it is within the range, it is the constant power mode, which is also the main working mode of the flywheel. In this mode, the machine-side converter will be controlled according to the principle that the output power of the machine-side converter remains unchanged to charge or discharge the flywheel, thus ensuring the charging and discharging stability of the flywheel and the power supply quality. Figure 5 In constant power mode, since the output power remains constant and the motor runs in the weak magnetic range, the torque will decrease after entering the constant power mode. In addition, in constant power mode, if the flywheel is in a discharge condition, as the energy is released, when the flywheel speed drops to a level that cannot meet the discharge power requirement of the constant power mode (that is, the flywheel speed is lower than the switching speed n s ), it is necessary to switch from the constant power mode to the above constant current mode to continue the discharge.

[0110] There may be multiple specific implementations for keeping the output power of the machine-side converter constant. For example, in a specific implementation of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system. The method described in step S103 of controlling the machine-side converter according to the principle that the output current of the machine-side converter remains constant to charge or discharge the flywheel may specifically include:

[0111] Under charging conditions, the first power given value P ref1 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [0, i pow _ lim ] is limited, and the result is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system. ;

[0112] Under the discharge condition, the second power given value P ref2 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [-i pow _ lim , 0] is limited, and the result is used as the q-axis current target quantity currently used by the double closed-loop feedback control system. ;

[0113] Based on the double closed-loop feedback control system, the machine-side converter is controlled to charge or discharge the flywheel;

[0114] Among them, the first power given value P ref1 Greater than 0, the second power setting value P ref1 Less than 0, i pow _ lim is the preset second limit value and i pow _ lim Greater than 0.

[0115] In this embodiment, the outer loop q-axis target quantity of the dual closed-loop feedback control system is the power given value P ref , and during charging and discharging, P ref The value of is different. Still taking charging as an example, the first power given value P ref1 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback, the error between the two is obtained and input into the PI controller, and the outer loop q-axis output can be generated through feedback control. Fig. 9 , is a schematic diagram of the principle of a constant power mode in a specific implementation. After the outer loop q-axis output is generated by feedback control, the outer loop q-axis output also needs to be passed through the range [0, i pow _ lim ] is limited, and the result obtained will be used as the q-axis current target quantity currently used by the dual closed-loop feedback control system .

[0116] In addition, it should be noted that the i in the above q _ lim It is usually a smaller value to ensure constant current. In this implementation, since the first power given value P ref1 As the outer loop q-axis target value of the double closed-loop feedback control system, even if [0, i pow _ lim], generally speaking, it can also ensure the stability of the output power of the machine-side converter. Of course, in order to avoid interference and other reasons during charging, the q-axis current target becomes a negative number, so the row [0, i pow _ lim ], that is, compared to i q _ lim ,i pow _ lim It can be set to a larger value, for example, it can be set to a larger value based on the hardware situation, as long as the output power of the machine-side converter does not exceed the maximum power allowed by the hardware.

[0117] The discharge process is similar to this. The second power given value P ref2 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback, the error between the two is input into the PI controller, and the outer loop q-axis output can be generated through feedback control. And because the current direction is opposite to that during charging, the range used is [-i pow _ lim , 0], so that the q-axis current target value will not appear during discharge It is positive and ensures that the output power of the machine-side converter does not exceed the maximum power allowed by the hardware.

[0118] In this embodiment, the same control architecture is used for charging and discharging conditions in constant power mode to generate the required q-axis current target value. , but the power given value P used during charging and discharging ref Different, and different range restrictions, that is, there is no need to set up completely different dual closed-loop feedback control systems for charging conditions and discharging conditions in constant power mode, which improves the versatility of the present application solution.

[0119] In a specific embodiment of the present invention, it may also include:

[0120] When the speed of the flywheel is greater than or equal to the maximum speed n max When the flywheel speed is maintained at the maximum speed n max The principle of controlling the machine-side converter is adopted.

[0121] In the above text, between 0 and the maximum speed n max In the range of , three different modes are divided. This implementation mode takes into account that when the speed of the flywheel is greater than or equal to the maximum speed n max When the flywheel is rotated, a mode can be set, which can be called a hold mode or a low power mode. In this mode, the maximum speed n is maintained according to the speed of the flywheel.max The principle of controlling the machine-side converter makes the flywheel speed reach the maximum speed n max After that, the motor can be driven with the minimum current to maintain the current speed. At this time, the flywheel will neither continue to charge nor discharge. In practical applications, continuously charging the flywheel will make the flywheel speed reach the maximum speed n max If the flywheel is not discharged at this time, the flywheel speed needs to be maintained at the maximum speed n max , that is, maintain the hold mode. Figure 5 In the holding mode, the speed can be maintained constant, and the torque and power are both small values, ensuring lower power consumption.

[0122] In a specific embodiment of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system. max When the flywheel speed is maintained at the maximum speed n max The principle of controlling the machine-side converter can specifically include:

[0123] When the speed of the flywheel is greater than or equal to the maximum speed n max When the maximum speed n max As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ;

[0124] The double closed-loop feedback control system controls the generator-side converter to maintain the flywheel speed at the maximum speed n max .

[0125] Considering that the control system used by the machine-side controller is usually a double closed-loop feedback control system, in the holding mode, the machine-side converter can also be controlled based on the double closed-loop feedback control system. Specifically, since the speed of the flywheel needs to be maintained at the maximum speed n max , so the maximum speed n can be max As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback, the error between the two is obtained, and the error is input into the PI controller, and the result is used as the q-axis current target value. .

[0126] It can be seen that the holding mode in this embodiment is substantially similar to the speed mode in the above embodiment, both of which are based on the feedback control of the rotation speed to obtain the q-axis current target value. , the same control loop can be used. The only difference is that in the hold mode, the outer loop q-axis target value is a fixed value (maximum speed n max ) instead of a dynamically increasing value like in speed mode.

[0127] In a specific embodiment of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system; the control method of flywheel energy storage may also include:

[0128] After the flywheel shutdown operation is started, when the flywheel speed is greater than or equal to the switching speed n s When the third power given value P ref3 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [-i pow _ lim , 0] is limited, and the result is used as the q-axis current target quantity currently used by the double closed-loop feedback control system. ; Based on the double closed-loop feedback control system, the machine-side converter is controlled to reduce the speed of the flywheel;

[0129] When the speed of the flywheel is less than the switching speed n s When 0 is used as the outer loop q-axis target value of the dual closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ; Based on the double closed-loop feedback control system, the machine-side converter is controlled until the speed of the flywheel is reduced to 0;

[0130] Among them, the third power given value P ref3 Less than 0, i pow _ lim is the preset second limit value and i pow _ lim Greater than 0.

[0131] When the flywheel needs to be shut down, one way is to directly cut off the power. At this time, the flywheel will continue to rotate due to inertia until it stops completely after a long time. For example, in some cases, it takes several days to stop, making the shutdown time very long. In this regard, this implementation method takes into account that the discharge can be carried out in the reverse process of the charging process to achieve a quick shutdown.

[0132] Specifically, when the speed of the flywheel is greater than or equal to the switching speed n s When the third power given value P ref3As the outer loop q-axis target quantity of the double closed-loop feedback control system, that is, discharge is performed based on the principle of the above constant power mode. Since it is discharge, the third power given value P ref3 It needs to be less than 0, and in actual application, in order to achieve rapid shutdown, the third power setting value P ref3 It can be a lower value, for example, it can be equal to the second power setting value P ref2 , can also be lower than P ref2 This causes the flywheel speed to drop rapidly.

[0133] Since the constant power mode is used at this time, specifically constant power deceleration, the outer ring q-axis output obtained will also pass through the range [-i pow _ lim , 0] is limited, and the result after limitation is used as the q-axis current target value That is to say, for the case of flywheel shutdown, when the speed is greater than or equal to the switching speed n s When the constant power mode is used for discharge, the outer ring q-axis target value is set to P ref3 , no additional modes need to be set, which facilitates the implementation of the solution.

[0134] When the speed of the flywheel is less than the switching speed n s When the flywheel speed is less than the switching speed n, one way is to first discharge quickly according to the constant current mode above, and then discharge according to the speed mode until the flywheel speed drops to 0. This implementation method takes into account that in order to achieve fast shutdown and simplify the process, when the flywheel speed is less than the switching speed n s When discharging in speed mode, in order to discharge quickly, 0 is used as the outer loop q-axis target value of the dual closed-loop feedback control system, and the current speed feedback value n is used as the target value of the outer loop q-axis of the dual closed-loop feedback control system. fed As the outer loop q-axis feedback, the error between the two is input into the PI controller to obtain the q-axis current target value. , thereby controlling the machine-side converter based on the double closed-loop feedback control system until the speed of the flywheel drops to 0.

[0135] In a specific embodiment of the present invention, it may also include:

[0136] When the flywheel speed is higher than the minimum operating speed n min When the grid-side converter fails and the generator-side converter is normal, the generator-side converter is controlled according to the principle of maintaining the bus voltage unchanged to charge or discharge the flywheel.

[0137] This embodiment takes into account that when the speed of the flywheel is not higher than the minimum operating speed n minIf the grid-side converter fails, the flywheel speed is low and the converter can be shut down and fault handling can be performed directly. min When the grid-side converter fails and the machine-side converter is normal, although the grid-side converter fails, it can usually work in the diode rectification state, that is, it can still transmit the electric energy on the AC side to the DC bus. In this implementation, since the machine-side converter is normal, the machine-side converter can be controlled in constant voltage mode at this time, that is, the charging or discharging of the flywheel is still allowed at this time, and when controlling the machine-side converter, the control principle is to maintain the bus voltage unchanged. In addition, it should be noted that in some cases, the grid-side converter fails completely and cannot work in the diode rectification state. At this time, the machine-side converter can still be controlled in constant voltage mode, but only the discharge of the flywheel is allowed at this time.

[0138] In addition, when the machine-side converter fails, the charge and discharge control of the flywheel cannot be effectively performed. In this case, the flywheel can be allowed to rotate freely. When the machine-side converter returns to normal, the speed tracking function can be used to start the machine at high speed to ensure the stability of the start. It can be seen that the above abnormal conditions can be handled without stopping the machine and can be restored online.

[0139] In one embodiment, the control system used by the machine-side controller is a double closed-loop feedback control system; when the speed of the flywheel is higher than the minimum operating speed n min When the grid-side converter fails and the generator-side converter is normal, the generator-side converter is controlled in accordance with the principle of maintaining the bus voltage unchanged to charge or discharge the flywheel, which may specifically include:

[0140] The third voltage is set to a fixed value V ref3 As the outer loop q-axis target value of the double closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [-i q _ max ,i q _ max ] is limited, and the result is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system. ;

[0141] Based on the double closed-loop feedback control system, the machine-side converter is controlled to charge or discharge the flywheel;

[0142] Among them, i q _ max is the preset third limit value and i q _ max Greater than 0.

[0143] This implementation can refer to the constant current mode, see Figure 8 , the difference is that the outer loop q-axis target value is the third voltage given value V ref3 In practical applications, the third voltage given value V ref3 Can be set equal to U ref . The current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the bus voltage can effectively track the third voltage set value V ref3 . And in the constant current mode above, the outer ring q-axis output is used in the range [0, i q _ lim ] or [-i q _ lim , 0] is limited. In the case of a fault in this implementation mode, the voltage loop is no longer saturated, and the stability of the current cannot be well guaranteed. Therefore, it is only necessary to limit the q-axis output of the outer loop through the range [-i q _ max ,i q _ max ] to restrict it, i q _ max Usually greater than i q _ lim , which means that a wider range of restrictions is allowed. The q-axis current target value is obtained After that, the machine-side converter can be controlled based on the double closed-loop feedback control system to charge or discharge the flywheel. Figure 8 and Fig. 9 This fault condition is shown in both, indicating that no matter the flywheel speed is at the minimum operating speed n min To switching speed n s range, or at the switching speed n s To maximum speed n max The range can be described in this embodiment based on the third voltage given value V ref3 Perform constant pressure control.

[0144] In one specific embodiment of the present invention, reference 12 is a flowchart of a flywheel energy storage control method provided in another specific embodiment. After receiving the start command, the machine-side controller can switch between different modes according to the different flywheel speeds. Specifically, it can first be determined whether the flywheel speed is greater than the minimum operating speed n min If not, you can enter the speed mode to accelerate the flywheel, that is, charge. If the flywheel speed is greater than the minimum working speed n min , we can continue to determine whether the flywheel speed is greater than the switching speed n s If the flywheel speed is not greater than the switching speed ns , indicating that it can enter the constant current mode, and Fig.12 In the example, the charging condition is determined. If it is determined to be a charging condition, charging can be performed in the constant current mode. At this time, a positive current limit is given. That is, as described above, by setting the first voltage given value V ref1 Set to higher than U ref , and the outer ring q-axis output will pass through the range [0, i q _ lim ] to limit the positive current limit. On the contrary, it means that the discharge is in the constant current mode, and the negative current limit will be given at this time, that is, by setting the second voltage setting value V ref2 Set to below U ref , and the outer ring q-axis output will pass through the range [-i q _ lim , 0] to limit and realize negative current limit setting.

[0145] If the speed is greater than the switching speed n s But it is less than the maximum speed n max , indicating that the constant power mode can be entered, and Fig.12 In the example, the charging condition will be determined. If it is determined to be a charging condition, charging can be performed in the constant power mode. At this time, positive power will be given. That is, as described above, by setting the power given value P ref Set to positive, and the outer loop q-axis output will pass through the range [0, i pow _ lim ] to limit the positive power setting. On the contrary, it means that the discharge is in constant power mode, and negative power setting will be performed at this time, that is, by setting the power setting value P ref Set to negative, and the outer loop q-axis output will pass through the range [-i pow _ lim ,0] to limit the negative power setting. Finally, if the speed is greater than the maximum speed n max , it will enter the hold mode to achieve low power consumption operation.

[0146] also, Fig.12 The example also shows the fault situation. Specifically, the rectifier is abnormal, that is, the grid-side converter is faulty. As described above, if the grid-side converter can work in the diode rectification state at this time, the machine-side converter can adopt the constant voltage mode to realize the charge and discharge of the flywheel, and wait for the rectifier to return to normal, and then it can be restored online. If it is a machine-side converter fault, that is, the inverter is abnormal, the flywheel can be allowed to rotate freely at this time. When the machine-side converter returns to normal, it can be started on the fly through the speed tracking function to realize online recovery and ensure the stability of the startup.

[0147] Applying the technical solution provided by the embodiment of the present invention, when the flywheel is in a stationary state and the rotation speed reaches the maximum speed n max In the speed range, three different modes are divided to ensure the stability during charging and discharging. Specifically, the flywheel energy storage device includes a grid-side converter, a machine-side converter and a motor connected in sequence; a flywheel matched with the motor, a grid-side controller for controlling the grid-side converter, and a machine-side controller for controlling the machine-side converter. The control method of flywheel energy storage can be applied to the machine-side controller.

[0148] When the flywheel is stationary and the charging operation of the flywheel is started, the machine-side converter is controlled according to the principle that the acceleration of the flywheel rotation remains unchanged, so that the speed of the flywheel increases from zero to the preset minimum operating speed n min This mode is the speed mode. It is designed to take into account that the flywheel speed is low and cannot provide enough power. Therefore, charging can be performed, but it cannot effectively power the load. In addition, charging in the speed mode keeps the acceleration of the flywheel rotation constant, which can ensure the stability of the voltage and current, and the torque will be very stable, so that the flywheel speed can be stably increased from zero to the minimum working speed n. min .

[0149] When the flywheel speed is at the minimum working speed n min To the preset switching speed n s When it is within the range of , it is the constant current mode. At this time, the flywheel can provide a certain degree of electrical energy, so the flywheel can be charged or discharged. In this mode, the flywheel speed is not high enough to ensure stable power output. Therefore, the machine-side converter will be controlled according to the principle of keeping the output current of the machine-side converter unchanged, which can effectively ensure the output current stability of the machine-side converter and ensure the charging and discharging efficiency.

[0150] When the flywheel speed is at the switching speed n s To the preset maximum speed n max When it is within the range, it is the constant power mode, which is also the main working mode of the flywheel. In this mode, the machine-side converter will be controlled according to the principle that the output power of the machine-side converter remains unchanged to charge or discharge the flywheel, thus ensuring the charging and discharging stability of the flywheel and the power supply quality.

[0151] It can also be seen that when the present application scheme switches between different modes, the current speed of the flywheel can be used to determine which mode to switch to. The mode switching and charging and discharging switching are flexible and convenient, and can be switched online in real time. In summary, the present application scheme can effectively realize the control of flywheel energy storage. By selecting the appropriate mode, the charging and discharging efficiency is guaranteed, and the stability and power supply quality during charging and discharging are guaranteed, which is conducive to achieving the optimal control effect.

[0152] Corresponding to the above method embodiment, the embodiment of the present invention also provides a control system for flywheel energy storage, which can be referred to in correspondence with the above. The flywheel energy storage device includes: a grid-side converter, a machine-side converter and a motor connected in sequence; a flywheel matched with the motor, a grid-side controller for controlling the grid-side converter, and a machine-side controller for controlling the machine-side converter.

[0153] See also Fig.10 As shown, the control system of the flywheel energy storage may include:

[0154] The speed mode control unit 201 is used to control the generator-side converter according to the principle that the acceleration of the flywheel rotation remains unchanged when the flywheel is in a stationary state and the charging operation of the flywheel is started, so that the speed of the flywheel increases from zero to a preset minimum operating speed n min ;

[0155] The constant current mode control unit 202 is used to control the flywheel speed when it is at the minimum working speed n. min To the preset switching speed n s When the output current of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged to charge or discharge the flywheel;

[0156] The constant power mode control unit 203 is used to control the flywheel speed to switch speed n when the flywheel speed is at the switching speed n. s To the preset maximum speed n max When the output power of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output power of the machine-side converter remains unchanged to charge or discharge the flywheel;

[0157] Among them, the maximum speed n max >Switching speed n s >Minimum working speed n min >0.

[0158] In a specific embodiment of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system; the speed mode control unit 201 is specifically used to:

[0159] When the flywheel is stationary and the charging process of the flywheel is started, the current speed is set to the value n. ref As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ;

[0160] Based on the double closed-loop feedback control system, the machine-side converter is controlled so that the speed of the flywheel increases from zero to the preset minimum operating speed nmin ;

[0161] Among them, when the speed of the flywheel increases from zero to the minimum working speed n min In the process, the speed setting value n ref The value of increases from the set initial value to the minimum working speed n according to a fixed step size. min .

[0162] In a specific implementation of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system; the constant current mode control unit 202 is specifically used to:

[0163] When the flywheel speed is at the minimum working speed n min To the preset switching speed n s When the first voltage is set to V under charging conditions, ref1 As the outer loop q-axis target value of the double closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [0, i q _ lim ] is limited, and the result is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system. ;

[0164] Under the discharge condition, the second voltage is set to V ref2 As the outer loop q-axis target value of the double closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [-i q _ lim , 0] is limited, and the result is used as the q-axis current target quantity currently used by the double closed-loop feedback control system. ;

[0165] Based on the double closed-loop feedback control system, the machine-side converter is controlled to charge or discharge the flywheel;

[0166] Among them, V ref1 =U ref +a,V ref2 =U ref -b,U ref is the bus voltage reference value used by the grid-side controller to control the grid-side converter. a and b are both set to values ​​greater than 0. q _ lim is the preset first limit value and i q _ lim Greater than 0.

[0167] In a specific implementation of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system; the constant power mode control unit 203 is specifically used to:

[0168] When the flywheel speed is at the switching speed n s To the preset maximum speed n max When the first power given value P is within the range of ref1 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [0, i pow _ lim ] is limited, and the result is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system. ;

[0169] Under the discharge condition, the second power given value P ref2 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [-i pow _ lim , 0] is limited, and the result is used as the q-axis current target quantity currently used by the double closed-loop feedback control system. ;

[0170] Based on the double closed-loop feedback control system, the machine-side converter is controlled to charge or discharge the flywheel;

[0171] Among them, the first power given value P ref1 Greater than 0, the second power setting value P ref1 Less than 0, i pow _ lim is the preset second limit value and i pow _ lim Greater than 0.

[0172] In a specific embodiment of the present invention, a holding mode control unit is further included, which is used to:

[0173] When the speed of the flywheel is greater than or equal to the maximum speed n max When the flywheel speed is maintained at the maximum speed n max The principle of controlling the machine-side converter is adopted.

[0174] In a specific embodiment of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system; the holding mode control unit is specifically used to:

[0175] When the speed of the flywheel is greater than or equal to the maximum speed n max When the maximum speed n max As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ;

[0176] The double closed-loop feedback control system controls the generator-side converter to maintain the flywheel speed at the maximum speed n max .

[0177] In a specific embodiment of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system; and further includes a shutdown control module for:

[0178] After the flywheel shutdown operation is started, when the flywheel speed is greater than or equal to the switching speed n s When the third power given value P ref3 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [-i pow _ lim , 0] is limited, and the result is used as the q-axis current target quantity currently used by the double closed-loop feedback control system. ; Based on the double closed-loop feedback control system, the machine-side converter is controlled to reduce the speed of the flywheel;

[0179] When the speed of the flywheel is less than the switching speed n s When 0 is used as the outer loop q-axis target value of the dual closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ; Based on the double closed-loop feedback control system, the machine-side converter is controlled until the speed of the flywheel is reduced to 0;

[0180] Among them, the third power given value P ref3 Less than 0, i pow _ lim is the preset second limit value and i pow _lim Greater than 0.

[0181] In a specific embodiment of the present invention, an exception handling module is also included, which is used to:

[0182] When the flywheel speed is higher than the minimum operating speed n min , when the grid-side converter fails and the generator-side converter is normal, the generator-side converter is controlled in accordance with the principle of maintaining the bus voltage unchanged to charge or discharge the flywheel;

[0183] In a specific implementation of the present invention, the control system used by the machine-side controller is a double closed-loop feedback control system; the abnormality handling module is specifically used for:

[0184] The third voltage is set to a fixed value V ref3 As the outer loop q-axis target value of the double closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [-i q _ max ,i q _ max ] is limited, and the result is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system. ;

[0185] Based on the double closed-loop feedback control system, the machine-side converter is controlled to charge or discharge the flywheel;

[0186] Among them, i q _ max is the preset third limit value and i q _ max Greater than 0.

[0187] Corresponding to the above method and system embodiments, the embodiments of the present invention further provide a flywheel energy storage control device and a computer-readable storage medium, which can be referenced in correspondence with the above.

[0188] See also Fig.11 As shown, the control device of the flywheel energy storage may include:

[0189] Memory 301, used for storing computer programs;

[0190] The processor 302 is used to execute a computer program to implement the steps of the flywheel energy storage control method in any of the above embodiments.

[0191] The computer readable storage medium stores a computer program, and when the computer program is executed by the processor, the steps of the flywheel energy storage control method in any of the above embodiments are implemented. The computer readable storage medium mentioned here includes random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, register, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the technical field.

[0192] It should also be noted that, in this application, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0193] Those skilled in the art may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this application can be implemented by electronic hardware, computer software or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to the function. 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 the present invention. Specific examples are used in this application to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. A control method for flywheel energy storage, characterized in that: The flywheel energy storage device includes: a grid-side converter, a machine-side converter and a motor connected in sequence; a flywheel matched with the motor, used to control a grid-side controller of the grid-side converter, and used to control a machine-side controller of the machine-side converter; the control method of the flywheel energy storage is applied to the machine-side controller, including: When the flywheel is in a stationary state and the charging operation of the flywheel is started, the generator-side converter is controlled according to the principle that the rotational acceleration of the flywheel remains unchanged, so that the speed of the flywheel increases from zero to a preset minimum operating speed n min ; When the speed of the flywheel is at the minimum operating speed n min To the preset switching speed n s When the output current of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged, so as to charge or discharge the flywheel; When the speed of the flywheel is at the switching speed n s To the preset maximum speed n max When the output power of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output power of the machine-side converter remains unchanged, so as to charge or discharge the flywheel; Among them, the maximum speed n max >The switching speed n s >The minimum operating speed n min >0.

2. The flywheel energy storage control method according to claim 1, characterized in that: The control system used by the machine-side controller is a double closed-loop feedback control system; The machine-side converter is controlled according to the principle that the rotational acceleration of the flywheel remains unchanged, so that the speed of the flywheel increases from zero to a preset minimum operating speed n min ,include: Set the current speed to the given value n ref As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ; Based on the dual closed-loop feedback control system, the generator-side converter is controlled so that the speed of the flywheel increases from zero to a preset minimum operating speed n min ; Wherein, when the speed of the flywheel increases from zero to the minimum working speed n min During the process, the speed given value n ref The value of increases from the set initial value to the minimum working speed n according to a fixed step size. min .

3. The flywheel energy storage control method according to claim 1, characterized in that: The control system used by the machine-side controller is a double closed-loop feedback control system; The machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged to charge or discharge the flywheel, including: Under charging conditions, the first voltage is set to a value V ref1 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [0, i q _ lim ] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ; Under the discharge condition, the second voltage is set to V ref2 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [-i q _ lim , 0] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ; Controlling the machine-side converter based on the dual closed-loop feedback control system to charge or discharge the flywheel; Among them, V ref1 =U ref +a,V ref2 =U ref -b,U ref is the bus voltage given value used by the grid-side controller to control the grid-side converter, a and b are both set to values ​​greater than 0, i q _ lim is the preset first limit value and i q _ lim Greater than 0.

4. The flywheel energy storage control method according to claim 1, characterized in that: The control system used by the machine-side controller is a double closed-loop feedback control system; The machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged to charge or discharge the flywheel, including: Under charging conditions, the first power given value P ref1 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is passed through the range [0, i pow _ lim ] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ; Under the discharge condition, the second power given value P ref2 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [-i pow _ lim , 0] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ; Controlling the machine-side converter based on the dual closed-loop feedback control system to charge or discharge the flywheel; Among them, the first power given value P ref1 Greater than 0, the second power setting value P ref1 Less than 0, i pow _ lim is the preset second limit value and i pow _ lim Greater than 0.

5. The flywheel energy storage control method according to claim 1, characterized in that: Also includes: When the speed of the flywheel is greater than or equal to the maximum speed n max When the speed of the flywheel is maintained at the maximum speed n max The machine-side converter is controlled according to the principle of 6. The flywheel energy storage control method according to claim 5, characterized in that: The control system used by the machine-side controller is a double closed-loop feedback control system; When the speed of the flywheel is greater than or equal to the maximum speed n max When the speed of the flywheel is maintained at the maximum speed n max The principle of controlling the machine-side converter includes: When the speed of the flywheel is greater than or equal to the maximum speed n max When the maximum speed n max As the outer loop q-axis target value of the double closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ; Based on the dual closed-loop feedback control system, the generator-side converter is controlled so that the speed of the flywheel is maintained at the maximum speed n max .

7. The flywheel energy storage control method according to claim 1, characterized in that: The control system used by the machine-side controller is a double closed-loop feedback control system; the flywheel energy storage control method also includes: After the flywheel shutdown operation is started, when the speed of the flywheel is greater than or equal to the switching speed n s When the third power given value P ref3 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current power feedback value P fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [-i pow _ lim , 0] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ; Based on the dual closed-loop feedback control system, the machine-side converter is controlled to reduce the rotational speed of the flywheel; When the speed of the flywheel is less than the switching speed n s When 0 is used as the outer loop q-axis target value of the dual closed-loop feedback control system, the current speed feedback value n fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated through feedback control, and the outer loop q-axis output quantity is used as the q-axis current target quantity currently used by the dual closed-loop feedback control system ; Based on the dual closed-loop feedback control system, the machine-side converter is controlled until the speed of the flywheel is reduced to 0; Among them, the third power given value P ref3 Less than 0, i pow _ lim is the preset second limit value and i pow _ lim Greater than 0.

8. The flywheel energy storage control method according to any one of claims 1 to 7, characterized in that: Also includes: When the speed of the flywheel is higher than the minimum operating speed n min When the grid-side converter fails and the generator-side converter is normal, the generator-side converter is controlled in accordance with the principle of maintaining the bus voltage unchanged to charge or discharge the flywheel.

9. The flywheel energy storage control method according to claim 8, characterized in that: The control system used by the machine-side controller is a double closed-loop feedback control system; When the speed of the flywheel is higher than the minimum operating speed n min , when the grid-side converter fails and the generator-side converter is normal, controlling the generator-side converter according to the principle of maintaining the bus voltage unchanged to charge or discharge the flywheel, including: The third voltage is set to a fixed value V ref3 As the outer loop q-axis target value of the dual closed-loop feedback control system, the current bus voltage feedback value V fed As the outer loop q-axis feedback quantity, the outer loop q-axis output quantity is generated by feedback control, and the outer loop q-axis output quantity is passed through the range [-i q _ max ,i q _ max ] is limited, and the result is used as the q-axis current target value currently used by the dual closed-loop feedback control system. ; Controlling the machine-side converter based on the dual closed-loop feedback control system to charge or discharge the flywheel; Among them, i q _ max is the preset third limit value and i q _ max Greater than 0.

10. A flywheel energy storage control system, characterized in that: The flywheel energy storage device includes: a grid-side converter, a machine-side converter and a motor connected in sequence; a flywheel matched with the motor, a grid-side controller for controlling the grid-side converter, and a machine-side controller for controlling the machine-side converter; the control system of the flywheel energy storage includes: A speed mode control unit is used to control the generator-side converter according to the principle that the acceleration of the flywheel rotation remains unchanged when the flywheel is in a stationary state and the charging operation of the flywheel is started, so that the speed of the flywheel increases from zero to a preset minimum operating speed n min ; A constant current mode control unit is used to control the flywheel speed when the flywheel speed is at the minimum operating speed n min To the preset switching speed n s When the output current of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output current of the machine-side converter remains unchanged, so as to charge or discharge the flywheel; The constant power mode control unit is used for switching the flywheel speed to the switching speed n when the flywheel speed is at the switching speed n s To the preset maximum speed n max When the output power of the machine-side converter is within the range of , the machine-side converter is controlled according to the principle that the output power of the machine-side converter remains unchanged, so as to charge or discharge the flywheel; Among them, the maximum speed n max >The switching speed n s >The minimum operating speed n min >0.

11. A flywheel energy storage control device, characterized in that: include: Memory for storing computer programs; A processor, configured to execute the computer program to implement the steps of the flywheel energy storage control method as claimed in any one of claims 1 to 9.

12. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the flywheel energy storage control method according to any one of claims 1 to 9 are implemented.

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