Method, device, electronic equipment and storage medium for controlling a flywheel energy storage system

Abstract

The present disclosure relates to a method and device for controlling a flywheel energy storage system, electronic equipment and storage medium, and relates to the field of power generation. The method comprises the following steps: obtaining a reference power of the flywheel energy storage system; determining a reference angular velocity of a motor of the flywheel energy storage system according to the reference power; obtaining an actual angular velocity of the motor; determining a speed error according to the reference angular velocity and the actual angular velocity; determining an integral sliding mode surface corresponding to the speed error; and controlling the motor of the flywheel energy storage system according to the speed error and the integral sliding mode surface to smooth the output power of the generator set. In this way, the integral sliding mode surface is established for the speed error, the motor of the flywheel energy storage system is controlled to smooth the output power of the generator set, the problem of poor anti-interference ability and weak robustness of the traditional PI controller of the motor in the flywheel energy storage system is solved, the system can quickly respond to rapid changes under external interference, and the anti-interference ability and robustness of the motor are improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of power generation, and particularly relates to a method and device for controlling a flywheel energy storage system, an electronic device and a storage medium. BACKGROUND

[0002] With the promotion of emerging renewable energy, the importance of renewable energy generation is increasingly prominent. Due to the intermittency of renewable energy, in order to smooth the output power fluctuation of the generator unit caused by the randomness and intermittency of renewable energy, energy storage devices such as flywheel energy storage systems are gradually introduced into current power generation technology.

[0003] In flywheel energy storage technology, a permanent magnet synchronous motor is generally used for energy exchange with the outside world. Due to the particularity of flywheel design, it is difficult to install a position sensor for the permanent magnet synchronous motor, and a sensorless control technology needs to be used to control the permanent magnet synchronous motor. In a control system based on sensorless technology, a PI (Proportional Integral) controller is generally used to control the motor. The PI controller cannot well meet the requirements of nonlinear control of the permanent magnet synchronous motor. Under external disturbance, the PI controller cannot quickly respond to the rapid changes of the system, and the robustness of the system is poor. SUMMARY

[0004] To overcome the problems in the related art, the present disclosure provides a method and device for controlling a flywheel energy storage system, an electronic device and a storage medium.

[0005] According to a first aspect of an embodiment of the present disclosure, a method for controlling a flywheel energy storage system is provided, the method comprising:

[0006] obtaining a reference power of the flywheel energy storage system, the reference power comprising a demand power for smoothing the output power of the generator unit;

[0007] determining a reference angular velocity of a motor of the flywheel energy storage system according to the reference power;

[0008] obtaining an actual angular velocity of the motor;

[0009] determining a speed error according to the reference angular velocity and the actual angular velocity;

[0010] determining an integral sliding surface corresponding to the speed error;

[0011] controlling the motor of the flywheel energy storage system according to the speed error and the integral sliding surface, so as to smooth the output power of the generator unit.

[0012] Optionally, the obtaining the reference power of the flywheel energy storage system comprises:

[0013] obtaining an output power reference value of the generator set and the flywheel energy storage system;

[0014] obtaining actual generated power of the generator set;

[0015] determining a reference power of the flywheel energy storage system according to the output power reference value and the generated power.

[0016] Optionally, the determining the reference power of the flywheel energy storage system comprises:

[0017] obtaining an output power reference value of the generator set and the flywheel energy storage system;

[0018] obtaining actual generated power of the generator set;

[0019] determining a reference power of the flywheel energy storage system according to the output power reference value and the generated power.

[0020] Optionally, the determining the reference angular velocity of the motor of the flywheel energy storage system according to the reference power comprises:

[0021] determining a reference stored energy of the flywheel energy storage system according to the reference power;

[0022] determining the reference angular velocity according to the reference stored energy and a preset moment of inertia of a flywheel rotor of the flywheel energy storage system.

[0023] Optionally, the controlling the motor of the flywheel energy storage system according to the rotational speed error and the integral sliding mode surface to smooth the output power of the generator set comprises:

[0024] determining a system output of the motor according to the rotational speed error and the integral sliding mode surface through a preset improved exponential rate equation, the system output being a quadrature axis component of a stator current of the motor, the quadrature axis being a coordinate axis perpendicular to a rotor magnetic field direction in a motor rotor coordinate system;

[0025] controlling the motor of the flywheel energy storage system according to the system output to smooth the output power of the generator set.

[0026] Optionally, before the obtaining the reference power of the flywheel energy storage system, the method further comprises:

[0027] obtaining rotational speed information of the motor;

[0028] the obtaining the reference power of the flywheel energy storage system comprises:

[0029] In a case where the rotation speed information is greater than or equal to a preset network access rotation speed threshold, a reference power of the flywheel energy storage system is obtained.

[0030] Optionally, the method further comprises:

[0031] In a case where the rotation speed information is less than the network access rotation speed threshold, a rotor position and a weighted rotation speed information of the motor are obtained according to the rotation speed information.

[0032] The flywheel energy storage system is initialized for energy storage according to a preset motor target rotation speed, the rotor position and the weighted rotation speed information, until the re-obtained rotation speed information is greater than or equal to the network access rotation speed threshold.

[0033] Optionally, the obtaining of the rotor position and the weighted rotation speed information according to the rotation speed information comprises:

[0034] In a case where the rotation speed information is less than or equal to a preset first rotation speed threshold, the rotor position and the weighted rotation speed information of the motor are determined by an algorithm of injecting a high-frequency pulsating current signal, the first rotation speed threshold being less than the network access rotation speed threshold; or

[0035] In a case where the rotation speed information is greater than or equal to a preset second rotation speed threshold, the rotor position and the weighted rotation speed information of the motor are determined by an algorithm of an unscented Kalman filter, the second rotation speed threshold being greater than the first rotation speed threshold and less than the network access rotation speed threshold; or

[0036] In a case where the rotation speed information is greater than the first rotation speed threshold and less than the second rotation speed threshold, the rotor position and the weighted rotation speed information of the motor are determined by an algorithm combining the injection of the high-frequency pulsating current signal and the unscented Kalman filter.

[0037] According to a second aspect of the embodiments of the present disclosure, an apparatus for controlling a flywheel energy storage system is provided, and the apparatus comprises:

[0038] An obtaining module is configured to obtain a reference power of a flywheel energy storage system, the reference power comprising a required power for smoothing output power of a generator set; determine a reference angular velocity of a motor of the flywheel energy storage system according to the reference power; and obtain an actual angular velocity of the motor.

[0039] A determining module is configured to determine a rotation speed error according to the reference angular velocity and the actual angular velocity; and determine an integral sliding mode surface corresponding to the rotation speed error.

[0040] A control module is configured to control the motor of the flywheel energy storage system according to the rotation speed error and the integral sliding mode surface, so as to smooth the output power of the generator set.

[0041] Optionally, the obtaining module is further configured to:

[0042] obtain an output power reference value of the flywheel energy storage system;

[0043] obtain actual generated power of the generator set;

[0044] determine a reference power of the flywheel energy storage system according to the output power reference value and the generated power.

[0045] Optionally, the obtaining module is further configured to:

[0046] determine a reference stored energy of the flywheel energy storage system according to the reference power;

[0047] determine the reference angular velocity according to the reference stored energy and a preset moment of inertia of a flywheel rotor of the flywheel energy storage system.

[0048] Optionally, the control module is further configured to:

[0049] determine a system output of the motor according to the rotational speed error and the integral sliding mode surface, the system output being a quadrature axis component of a stator current of the motor, the quadrature axis being a coordinate axis perpendicular to a rotor magnetic field direction in a motor rotor coordinate system, the determining being performed by a preset modified exponential rate equation;

[0050] control the motor of the flywheel energy storage system according to the system output, so as to smooth output power of the generator set.

[0051] Optionally, the apparatus further comprises:

[0052] an initialization module configured to obtain rotational speed information of the motor;

[0053] the obtaining of the reference power of the flywheel energy storage system comprises:

[0054] in a case where the rotational speed information is greater than or equal to a preset grid-connected rotational speed threshold, obtaining the reference power of the flywheel energy storage system.

[0055] Optionally, the initialization module is further configured to:

[0056] in a case where the rotational speed information is less than the grid-connected rotational speed threshold, obtaining rotor position and weighted rotational speed information of the motor according to the rotational speed information;

[0057] performing initialization energy storage for the flywheel energy storage system according to a preset motor target rotational speed, the rotor position and the weighted rotational speed information, until re-obtained rotational speed information is greater than or equal to the grid-connected rotational speed threshold.

[0058] Optionally, the initialization module is further configured to:

[0059] In a case where the rotation speed information is less than or equal to a preset first rotation speed threshold, the rotor position and the weighted rotation speed information of the motor are determined by an algorithm of injecting a high-frequency pulse current signal, the first rotation speed threshold being less than the network access rotation speed threshold; or

[0060] In a case where the rotation speed information is greater than or equal to a preset second rotation speed threshold, the rotor position and the weighted rotation speed information of the motor are determined by an algorithm of an unscented Kalman filter, the second rotation speed threshold being greater than the first rotation speed threshold and less than the network access rotation speed threshold; or

[0061] In a case where the rotation speed information is greater than the first rotation speed threshold and less than the second rotation speed threshold, the rotor position and the weighted rotation speed information of the motor are determined by an algorithm combining the injection of the high-frequency pulse current signal and the unscented Kalman filter.

[0062] According to a third aspect of the embodiments of the present disclosure, an electronic device is provided, and the electronic device comprises:

[0063] a memory having a computer program stored thereon;

[0064] a processor configured to execute the computer program in the memory to implement the steps of the method in any of the embodiments of the first aspect.

[0065] According to a fourth aspect of the embodiments of the present disclosure, a non-transitory computer-readable storage medium is provided, and the medium has a computer program stored thereon, the program being executed by a processor to implement the steps of the method in the first aspect.

[0066] The technical solutions provided by the embodiments of the present disclosure can have the following beneficial effects:

[0067] The present disclosure obtains a reference power of a flywheel energy storage system, determines a reference angular velocity of a motor of the flywheel energy storage system according to the reference power, obtains an actual angular velocity of the motor, determines a rotation speed error according to the reference angular velocity and the actual angular velocity, and determines an integral sliding mode surface corresponding to the rotation speed error; and the motor of the flywheel energy storage system is controlled according to the rotation speed error and the integral sliding mode surface to smooth the output power of the generator set. In this way, the integral sliding mode surface is established for the rotation speed error, the motor of the flywheel energy storage system is controlled to smooth the output power of the generator set, the problem of poor anti-interference ability and weak robustness of the conventional PI controller of the motor in the flywheel energy storage system is solved, the system can quickly respond to the rapid changes under external interference, and the anti-interference ability and the robustness of the motor are improved.

[0068] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure.

[0069] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0070] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0071] Figure 1 This is a flowchart illustrating a method for controlling a flywheel energy storage system according to an exemplary embodiment.

[0072] Figure 2 This is a flowchart illustrating another method for controlling a flywheel energy storage system according to an exemplary embodiment.

[0073] Figure 3 This is a block diagram illustrating an apparatus for controlling a flywheel energy storage system according to an exemplary embodiment.

[0074] Figure 4 This is a block diagram illustrating another device for controlling a flywheel energy storage system according to an exemplary embodiment.

[0075] Figure 5 This is a block diagram illustrating an electronic device according to an exemplary embodiment. Detailed Implementation

[0076] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of this disclosure.

[0077] First, the application scenarios of this disclosure are explained. The SMC (Sliding Mode Control) involved in this disclosure can be applied to the control of sensorless permanent magnet synchronous motors. Power generation systems are a typical application. In power generation systems, flywheel energy storage systems used for energy storage convert kinetic energy into electrical energy and vice versa through permanent magnet synchronous motors, thereby smoothing the total power output of the generator set to the grid. For example, in wind power generation applications, when the actual power output of the wind turbine exceeds the smoothing power, the permanent magnet synchronous motor converts the excess electrical energy into kinetic energy and stores it in the flywheel energy storage system; in this case, the motor functions as a motor. When the actual power output of the wind turbine is lower than the smoothing power, the stored kinetic energy can be used to output power to the grid, thereby achieving the purpose of smoothing the total power output of the wind turbine to the grid; in this case, the motor operates as a generator.

[0078] In this disclosure, the reference power of the flywheel energy storage system is first obtained, and a reference angular velocity is obtained based on the reference power. An integral sliding surface is established using the speed error between the reference angular velocity and the actual angular velocity. The purpose of the integral sliding surface is to make the speed error approach a preset target value. Specifically, the integral sliding surface is made to approach the target value by a preset improved exponential approach rate equation. In this disclosure, the target value can be 0, so that the speed error between the actual motor angular velocity and the reference angular velocity approaches 0, thereby making the actual output power of the motor approach the reference power.

[0079] The present disclosure will now be described in conjunction with specific embodiments.

[0080] Figure 1 This is a flowchart illustrating a method for controlling a flywheel energy storage system according to an exemplary embodiment, such as... Figure 1 As shown, the method may include the following steps:

[0081] In step S101, the reference power of the flywheel energy storage system is obtained.

[0082] The reference power is the power required by the flywheel energy storage system to smooth the output power of the generator set.

[0083] In this step, the reference power can be obtained through the following steps:

[0084] First, obtain the reference value (i.e., smoothed power) of the total power output to the grid by the generator set and flywheel energy storage system.

[0085] In some possible implementations, the theoretical value of the generated power can be used as a reference value for the total power.

[0086] For example, the generator set can be a wind turbine generator set, and the total power reference value can be determined by the following formula.

[0087]

[0088] Among them, P ref This is a reference value for total power, where A is the swept area of ​​the wind turbine blades, which is related to the length of the wind turbine blades, and C... pmax The preset maximum wind energy utilization factor represents the conversion efficiency of the wind turbine in converting wind energy into electrical energy. For example, this wind energy utilization factor can be 0.593. Here, ρ represents the average wind speed, and ρ represents the air density, which is the mass of a unit volume of air under certain temperature and pressure conditions. For example, under standard conditions (0℃, 1 standard atmosphere), the air density can be 1.29 kg / m³. 3 .

[0089] The average wind speed can be determined using the following formula (2).

[0090]

[0091] Where V(t) is the wind speed function, t is the current time, τ is the integration interval, and τ < t.

[0092] Then, the actual power output of the generator set is obtained, and the difference between the total power reference value and the power output is used as the reference power.

[0093] The reference power can be positive or negative. When the reference power is positive, it indicates that the actual power output of the generator set does not reach the total power reference value. The flywheel energy storage system can output the reference power to the grid to bring the total power of the generator set and the flywheel energy storage system closer to the total power reference value. When the target power is negative, it indicates that the actual power output of the generator set exceeds the total power reference value. The flywheel energy storage system can store energy, converting the portion of the power output exceeding the total power reference value into kinetic energy.

[0094] In step S102, the reference angular velocity of the flywheel energy storage system is determined based on the reference power.

[0095] In some embodiments, the flywheel energy storage system may include a flywheel energy storage unit or a flywheel energy storage array composed of multiple flywheel energy storage units. The flywheel energy storage unit includes a flywheel, a motor, and a corresponding converter.

[0096] First, based on the number of flywheel energy storage units in the flywheel energy storage system, the target reference power of each flywheel energy storage unit is determined.

[0097] For example, the target reference power of each flywheel energy storage unit is determined according to the number of flywheel energy storage units in the flywheel energy storage system using the following formula three.

[0098]

[0099] in, Let be the target reference power of each flywheel energy storage unit in the flywheel energy storage system, be a function of time t, and let N be the number of flywheel energy storage units, where N is a natural number greater than or equal to 1.

[0100] Secondly, the reference stored energy of the flywheel energy storage unit is determined based on the target reference power.

[0101] For example, the reference stored energy of the flywheel energy storage unit is determined based on the target reference power, the initial energy of the flywheel energy storage unit, and Formula 4.

[0102]

[0103] Among them, E * E0 is the reference stored energy of the flywheel energy storage unit, and E0 is the initial energy of the flywheel energy storage unit at time t0. When the motor initially starts, this initial energy can be a preset initial value, such as 0. The target reference power is the power released or absorbed by the flywheel energy storage unit within time period t, where A value greater than or equal to 0 indicates that the flywheel energy storage unit needs to release power. A value less than 0 indicates that the flywheel energy storage unit needs to absorb power.

[0104] Then, the reference angular velocity is determined based on the reference stored energy and the preset moment of inertia of the flywheel rotor.

[0105] For example, the reference angular velocity is determined based on the reference stored energy, the preset moment of inertia of the flywheel rotor, and Formula 5.

[0106]

[0107] Where, ω * Let t be the reference angular velocity that the motor is expected to reach, and J be the preset moment of inertia of the flywheel rotor, which is a constant related to the structure and material design of the flywheel rotor.

[0108] In step S103, the actual angular velocity of the motor is obtained.

[0109] In step S104, the rotational speed error is determined based on the reference angular velocity and the actual angular velocity.

[0110] For example, the difference between the reference angular velocity and the actual angular velocity is taken as the angular velocity error.

[0111] x1=ω * -ω r (Formula Six)

[0112] Where x1 is the angular velocity error, ω * For reference angular velocity, ω r This is the actual angular velocity of the motor.

[0113] In step S105, the integral sliding surface corresponding to the rotational speed error is determined.

[0114] In this step, the integral sliding surface formula of the motor is determined as follows.

[0115] First, determine the integral sliding surface corresponding to the rotational speed error.

[0116] For example, the integral sliding surface is determined according to Formula 7 as follows:

[0117]

[0118] Where s is a defined integral sliding surface, c is an integral sliding surface constant greater than 0, and x1 is the angular velocity error.

[0119] Secondly, the derivative of the integral sliding surface is obtained by taking the derivative of the integral sliding surface.

[0120] For example, by differentiating Formula 7, we obtain the derivative formula of the integral sliding surface as shown in Formula 8.

[0121]

[0122] in, Differentiate the integral sliding surface with respect to t. Differentiate the angular velocity error with respect to t.

[0123] Then, by substituting the motor's magnetic moment equation and mechanical motion equation into the derivative formula, the integral sliding surface equation of the motor is obtained.

[0124] For example, substituting the electromagnetic torque equation shown in Formula 9 and the motor mechanical motion equation shown in Formula 10 into Formula 8 yields the integral sliding surface equation of the motor, as shown in Formula 11:

[0125]

[0126] Among them, T e p is the electromagnetic torque. n ψ is the preset number of motor pole pairs. f For the preset rotor permanent magnet flux linkage, i qThe system output to be determined is the quadrature axis component of the stator current of the motor. The quadrature axis is the coordinate axis in the motor rotor coordinate system that is perpendicular to the direction of the rotor magnetic field, and is also often referred to as the q-axis.

[0127]

[0128] Where J is the preset moment of inertia of the flywheel rotor, and T e For electromagnetic torque, T L Where ω is the preset load torque, D is the preset damping coefficient, and ω is the preset damping coefficient. r This is the actual angular velocity of the motor.

[0129]

[0130] Where, p n ψ is the preset number of motor pole pairs. f For the preset rotor permanent magnet flux linkage, i q The desired system output is given by J, where J is the preset moment of inertia of the flywheel rotor, and T is the value of T. L The preset motor load torque is ω. In this exemplary embodiment, the motor load is the flywheel in the flywheel energy storage unit, D is the preset damping coefficient, and ω is the load torque of the motor. r This is the actual angular velocity of the motor.

[0131] In step S106, the motor of the flywheel energy storage system is controlled according to the speed error and the integral sliding surface to smooth the output power of the generator set.

[0132] In this step, firstly, based on the speed error and the integral sliding surface, the system output of the motor is determined by a preset improved exponential approach rate equation. The system output is the cross-axis component of the stator current of the motor. The cross-axis is the coordinate axis perpendicular to the direction of the rotor magnetic field in the motor rotor coordinate system, also known as the q-axis.

[0133] The purpose of introducing this approach rate is to make the integral sliding surface approach a preset target value. In this embodiment, the preset target value can be 0, that is, the rotational speed error between the actual angular velocity and the reference angular velocity approaches 0.

[0134] For example, the improved exponential convergence rate is shown in Formula Twelve below.

[0135]

[0136] Where η, δ, ε, and k are all constants greater than 0, e is the natural constant, s is the integral sliding surface, and x1 is the angular velocity error.

[0137] For example, the final system output is determined according to Formula 11 of the integral sliding surface equation of the motor and Formula 12 of the improved exponential approach rate, as shown in Formula 13.

[0138]

[0139] Among them, i q The system output to be determined is given by η, δ, ε, k, and c, which are all constants greater than 0, e is the natural constant, s is the integral sliding surface, x1 is the angular velocity error, and ω... r The actual angular velocity of the motor is given by T, where J is the preset moment of inertia of the flywheel rotor, and T is the actual angular velocity of the motor. L Where D is the preset load torque, and p is the preset damping coefficient. n ψ is the preset number of motor pole pairs. f The permanent magnet flux linkage of the motor rotor is preset. In some embodiments, typical values ​​of the above constants can be ε = 10, k = 30, η = 0.1, σ = 20, c = 15, D = 0.

[0140] Secondly, the motor of the flywheel energy storage system is controlled based on the output of this system to smooth the output power of the generator set.

[0141] The system output controls the motor of the flywheel energy storage system, which outputs power to the grid through the flywheel energy storage system so that the total power of the generator set and the flywheel energy storage system tends to the total power reference value. Alternatively, the flywheel energy storage system can store energy and convert the portion of the generator set's power output that exceeds the total power reference value into kinetic energy.

[0142] The above technical solution establishes an integral sliding surface for speed error, controls the motor of the flywheel energy storage system to smooth the output power of the generator set, solves the problems of poor anti-interference capability and weak robustness of the traditional PI controller of the motor in the flywheel energy storage system, and can respond quickly to rapid changes in the system under external interference, thus improving the anti-interference and robustness of the motor.

[0143] When controlling a motor without sensors, accurate rotor position is crucial. This disclosure introduces an unscented Kalman filter algorithm into the motor of a flywheel energy storage system. However, this technique estimates rotor position and angular velocity using the back electromotive force (EMF) generated by the motor. In flywheel energy storage systems, the back EMF is too small during startup and low-speed phases, making accurate rotor position acquisition difficult. Furthermore, the flywheel represents a significant load for a permanent magnet synchronous motor (PMSM), making startup even more challenging under load. Therefore, to ensure stable control performance during startup and low-speed conditions, an algorithm injecting a high-frequency pulsating current signal is used to detect rotor position and angular velocity. In summary, this disclosure uses an algorithm combining high-frequency pulsating current signal injection and an unscented Kalman filter to control the motor in this flywheel energy storage system.

[0144] Figure 2 This is a flowchart illustrating a method for controlling a flywheel energy storage system according to an exemplary embodiment, such as...Figure 2 As shown, prior to step S101, the method may further include the following steps:

[0145] In step S201, the motor speed information is obtained.

[0146] First, the electrical angular velocity of the motor rotor is obtained and used as the rotational speed information. The electrical angular velocity of the motor is the product of the actual angular velocity and the preset number of motor pole pairs. During motor operation, the rotational speed information can be historical rotational speed information. When the motor starts, the rotational speed information can be a preset initial value, such as 0.

[0147] In step S202, it is determined whether the speed information is greater than or equal to the preset grid access speed threshold.

[0148] The flywheel energy storage system can be divided into two stages: initial energy storage and grid connection smoothing power. In the initial energy storage stage, the flywheel energy storage system relies on grid power to convert electrical energy into kinetic energy, thereby storing energy. When the rotational speed information is greater than or equal to a preset grid connection speed threshold, the initial energy storage stage is confirmed to have ended, and the system enters the grid connection smoothing power stage.

[0149] In step S203, if the rotational speed information is less than the preset grid connection speed threshold, the rotor position and weighted speed information of the motor are obtained based on the rotational speed information.

[0150] For example, obtaining the rotor position and weighted speed information of the motor based on the speed information can include the following three cases:

[0151] In the first scenario, when the rotational speed information is less than or equal to a preset first rotational speed threshold, the rotor position and weighted rotational speed information of the motor can be determined by an algorithm that injects a high-frequency pulsed current signal.

[0152] The first speed threshold is less than the grid access speed threshold.

[0153] When using an algorithm based on an unscented Kalman filter for a permanent magnet synchronous motor, this technique estimates the rotor position and speed of the motor by utilizing the back electromotive force generated by the motor. Since the back electromotive force is proportional to the change in magnetic flux per unit time, the change in magnetic flux is small during motor startup and low-speed phases due to the low speed, resulting in a small back electromotive force and making it difficult to accurately estimate the rotor position. To solve this problem, when the speed information is less than or equal to a preset first speed threshold (e.g., the first speed threshold is 400), the rotor position of the motor is determined by an algorithm that injects a high-frequency pulsating current signal along the direct axis. Here, the direct axis is the coordinate axis (also known as the d-axis) of the rotor magnetic field direction in the motor rotor coordinate system.

[0154] For example, the basic process of determining the rotor position of a motor using an algorithm that injects a high-frequency pulsating current signal along the direct shaft is as follows:

[0155] Step 1: Inject high-frequency pulsating current only into the direct axis of the motor rotor coordinate system. The expression of its signal can be expressed as Formula XIV.

[0156]

[0157] in, This refers to the direct-axis current under high-frequency current excitation. I is the quadrature-axis current under high-frequency current excitation. mh ω is the amplitude of the injected high-frequency current signal. h The angular frequency of the injected high-frequency current signal.

[0158] Step 2: Substitute Formula 14 into the mathematical model of the permanent magnet synchronous motor to obtain the high-frequency voltage response expression represented by Formula 15.

[0159]

[0160] in, The high-frequency voltage response is on the quadrature axis, and ΔL is the dq-axis differential-mode inductance. I mh ω is the amplitude of the injected high-frequency current. h The angular frequency of the injected high-frequency current signal.

[0161] Step 3, through cosω h t The signal is modulated and then the DC component is extracted by a low-pass filter to obtain the signal represented by the following formula sixteen.

[0162]

[0163] Among them, f c (Δθ) is the rotor position error function, and the LPF (Low Pass Filter) can extract the DC component from the signal. The high-frequency voltage response is on the quadrature axis, and ΔL is the dq-axis differential-mode inductance. I mh ω is the amplitude of the injected high-frequency current. h The angular frequency of the injected high-frequency current.

[0164] When Δθ is very small, sin(2Δθ)≈2Δθ, resulting in Formula XVII.

[0165] f c (Δθ)≈ω h I m ΔLΔθ (Formula 17)

[0166] Step 4: Adjust f using the PI controller. c When (Δθ) approaches 0, the PI controller output is the rotor position estimate.

[0167] The PI controller is a linear controller that uses the control deviation between the given value and the actual output value to form a control quantity by linearly combining the proportional and integral of the deviation, thereby controlling the controlled object.

[0168] Alternatively, the first estimated rotational speed can be obtained through high-frequency pulsed current, and this first estimated rotational speed can be used as the weighted rotational speed information. For specific steps, please refer to the relevant technical descriptions, which will not be elaborated here.

[0169] In the second scenario, if the rotational speed information is greater than or equal to the preset second rotational speed threshold, the rotor position and weighted rotational speed information of the motor can be determined by the algorithm of the unscented Kalman filter.

[0170] Among them, the second speed threshold is greater than the first speed threshold and less than the grid access speed threshold.

[0171] For example, the second speed threshold can be 1000. When the speed information is greater than or equal to the preset second speed threshold, the rotor position of the motor and the second estimated speed are determined by the algorithm of the unscented Kalman filter. The second estimated speed is used as the weighted speed information. The specific steps can be referred to the relevant technical description, which will not be elaborated here.

[0172] In the third scenario, when the rotational speed information is greater than the first rotational speed threshold but less than the second rotational speed threshold, an algorithm combining injected high-frequency pulsating current signal and an unscented Kalman filter can be used to determine the rotor position and weighted rotational speed information of the motor.

[0173] For example, the first speed threshold is 400, and the second speed threshold is 1000. When the speed information is greater than the first speed threshold and less than the second speed threshold, an algorithm combining injected high-frequency pulsating current signal and unscented Kalman filter is used to determine the rotor position of the motor. The specific steps are as follows:

[0174] Step 1: Obtain the first estimated rotational speed using the direct-axis injection of high-frequency pulsating current signal method.

[0175] Step 2: Use the unscented Kalman filter method to obtain the second estimated rotational speed.

[0176] Step 3: Obtain the speed weighting coefficient based on the speed information, the first speed threshold, and the second speed threshold.

[0177] For example, based on the rotational speed information, the first rotational speed threshold and the second rotational speed threshold are obtained by formula 18 as follows:

[0178]

[0179] Where α is the speed weighting coefficient, ω1 is the first speed threshold, ω2 is the second speed threshold, and ω e This provides the motor's rotational speed information.

[0180] It should be noted that the determination of the first speed threshold and the second speed threshold is related to the motor design. In some implementations, the first speed threshold and the second speed threshold can be determined according to the following principles:

[0181] The first speed threshold ω1 must be higher than the minimum speed at which the unscented Kalman filter can work accurately; the second speed threshold ω1 must be lower than the maximum speed at which the high-frequency pulse current signal injection method can work accurately, and must be able to meet the requirements for motor self-starting. For example, the first speed threshold can be 400 and the second speed threshold can be 1000.

[0182] Step 4: Determine the weighted speed information of the motor based on the first estimated speed, the second estimated speed, and the speed weighting coefficient.

[0183] For example, the speed information is corrected using Formula Nineteen based on the first estimated speed, the second estimated speed, and the speed weighting coefficient.

[0184] ω e =αω g +βω k (Formula 19)

[0185] Where α is the speed weighting coefficient, β = 1 - α, ω g For the first estimated rotational speed, ω k For the second estimated rotational speed, ω e This is weighted rotational speed information.

[0186] Step 5: Integrate the weighted speed information to obtain the rotor position of the motor.

[0187] For example, the rotor position of the motor can be obtained by integrating the weighted speed information with reference to Formula 20.

[0188] θ=∫ω e dt (Formula 20)

[0189] Where θ is the rotor position of the electron, ω e This is weighted rotational speed information.

[0190] In step S204, the flywheel energy storage system is initialized based on the preset target motor speed and rotor position.

[0191] In this step, the flywheel energy storage system is initialized with energy storage based on the preset target motor speed and rotor position. The preset motor speed is greater than the grid connection speed threshold. The flywheel energy storage system is initialized with energy storage based on the motor speed and rotor position until the motor speed information is greater than the grid connection speed threshold, thereby entering the grid connection smoothing power stage.

[0192] It should be noted that during the grid connection smoothing phase, if the motor's speed information is less than a preset minimum energy storage threshold, energy storage will be performed without power smoothing until the speed information is greater than or equal to the minimum energy storage threshold. In some possible implementations, the minimum energy storage threshold can be the product of the grid connection speed threshold and the minimum energy storage coefficient; for example, the minimum energy storage coefficient can be 30%.

[0193] In summary, this disclosure uses an algorithm that combines injected high-frequency pulsating current signals and unscented Kalman filters to control the motor. This solves the problem that it is difficult to accurately estimate the rotor position angle of the motor during startup and low-speed phases due to the small change in magnetic flux at low speeds. The system can also achieve stable control performance under startup and low-speed conditions.

[0194] Furthermore, for the sake of simplicity, the above method embodiments are all described as a series of actions. However, those skilled in the art should understand that this disclosure is not limited to the described order of actions. Secondly, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this disclosure.

[0195] Figure 3 This is a block diagram illustrating a device for controlling a flywheel energy storage system according to an exemplary embodiment, such as... Figure 3 As shown, the device 300 for controlling the flywheel energy storage system includes:

[0196] The acquisition module 301 is configured to acquire the reference power of the flywheel energy storage system, the reference power including the required power for smoothing the output power of the generator set; determine the reference angular velocity of the motor of the flywheel energy storage system based on the reference power; and acquire the actual angular velocity of the motor.

[0197] The determination module 302 is configured to determine the rotational speed error based on the reference angular velocity and the actual angular velocity; and to determine the integral sliding surface corresponding to the rotational speed error.

[0198] The control module 303 is configured to control the motor of the flywheel energy storage system based on the speed error and the integral sliding surface to smooth the output power of the generator set.

[0199] Optionally, the acquisition module 301 is also configured to:

[0200] Obtain reference values ​​for the output power of the generator set and flywheel energy storage system;

[0201] Obtain the actual power output of the generator set;

[0202] The reference power of the flywheel energy storage system is determined based on the output power reference value and the power generation.

[0203] Optionally, the acquisition module 301 is also configured to:

[0204] The reference stored energy of the flywheel energy storage system is determined based on the reference power.

[0205] The reference angular velocity is determined based on the reference stored energy and the preset moment of inertia of the flywheel rotor of the flywheel energy storage system.

[0206] Optionally, the control module 303 is also configured to:

[0207] Based on the speed error and the integral sliding surface, the system output of the motor is determined by the preset improved exponential approach rate equation. The system output is the cross-axis component of the stator current of the motor, and the cross-axis is the coordinate axis perpendicular to the direction of the rotor magnetic field in the motor rotor coordinate system.

[0208] The system output controls the motor of the flywheel energy storage system to smooth the output power of the generator set.

[0209] Figure 4 This is a block diagram illustrating a device for controlling a flywheel energy storage system according to an exemplary embodiment, such as... Figure 4 As shown, the device 300 for controlling the flywheel energy storage system further includes:

[0210] Initialization module 304 is configured to acquire motor speed information;

[0211] Obtaining the reference power of the flywheel energy storage system includes:

[0212] When the rotational speed information is greater than or equal to the preset grid connection speed threshold, the reference power of the flywheel energy storage system is obtained.

[0213] Optionally, initialization module 304 is also configured as follows:

[0214] If the rotational speed is less than the grid access speed threshold, the rotor position and weighted rotational speed information of the motor are obtained based on the rotational speed information.

[0215] Based on the preset target motor speed, rotor position, and weighted speed information, the flywheel energy storage system is initialized for energy storage until the re-acquired speed information is greater than or equal to the grid connection speed threshold.

[0216] Optionally, initialization module 304 is also configured as follows:

[0217] If the rotational speed information is less than or equal to a preset first rotational speed threshold, the rotor position and weighted rotational speed information of the motor are determined by an algorithm that injects a high-frequency pulsed current signal, where the first rotational speed threshold is less than the grid connection speed threshold; or,

[0218] If the rotational speed information is greater than or equal to a preset second rotational speed threshold, the rotor position and weighted rotational speed information of the motor are determined using an unscented Kalman filter algorithm. The second rotational speed threshold is greater than the first rotational speed threshold and less than the grid connection speed threshold; or,

[0219] When the rotational speed information is greater than the first rotational speed threshold and less than the second rotational speed threshold, an algorithm combining injected high-frequency pulsating current signal and unscented Kalman filter is used to determine the rotor position and weighted rotational speed information of the motor.

[0220] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0221] In the above technical solution, an integral sliding surface is established for the speed error, and the motor of the flywheel energy storage system is controlled to smooth the output power of the generator set. This solves the problems of poor anti-interference ability and weak robustness of the traditional PI controller of the motor in the flywheel energy storage system. It can also respond quickly to the rapid changes of the system under external interference, thereby improving the anti-interference and robustness of the motor.

[0222] In the above technical solution, the algorithm that combines the injection of high-frequency pulsating current signal and the unscented Kalman filter to control the motor can solve the problem that it is difficult to accurately estimate the rotor position angle of the motor during the start-up and low-speed stages due to the small change in magnetic flux at low speed. The system can also obtain stable control performance under the conditions of start-up and low speed.

[0223] Figure 5 This is a block diagram illustrating an electronic device 500 according to an exemplary embodiment. For example... Figure 5 As shown, the electronic device 500 may include a processor 501 and a memory 502. The electronic device 500 may also include one or more of a multimedia component 503, an input / output (I / O) interface 504, and a communication component 505.

[0224] The processor 501 controls the overall operation of the electronic device 500 to complete all or part of the steps in the method for controlling the flywheel energy storage system described above. The memory 502 stores various types of data to support the operation of the electronic device 500. This data may include, for example, instructions for any application or method operating on the electronic device 500, and application-related data such as contact data, sent and received messages, pictures, audio, video, etc. The memory 502 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. Multimedia component 503 may include a screen and an audio component. The screen may be, for example, a touchscreen, and the audio component is used to output and / or input audio signals. For example, the audio component may include a microphone for receiving external audio signals. The received audio signals may be further stored in memory 502 or transmitted via communication component 505. The audio component also includes at least one speaker for outputting audio signals. I / O interface 504 provides an interface between processor 501 and other interface modules, such as a keyboard, mouse, buttons, etc. These buttons may be virtual or physical buttons. Communication component 505 is used for wired or wireless communication between the electronic device 500 and other devices. Wireless communication, such as Wi-Fi, Bluetooth, Near Field Communication (NFC), 2G, 3G, 4G, NB-IoT, eMTC, or other 5G technologies, or combinations thereof, is not limited here. Therefore, the corresponding communication component 505 may include: a Wi-Fi module, a Bluetooth module, an NFC module, etc.

[0225] In another exemplary embodiment, a non-transitory computer-readable storage medium including program instructions is also provided, which, when executed by a processor, implement the steps of the method for controlling the flywheel energy storage system described above. For example, the computer-readable storage medium may be the memory 502 including the program instructions described above, which may be executed by the processor 501 of the electronic device 500 to complete the method for controlling the flywheel energy storage system described above.

[0226] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of this disclosure. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0227] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A method of controlling a flywheel energy storage system, characterized by, The method comprises: acquiring a reference power of a flywheel energy storage system, the reference power comprising a required power for smoothing an output power of a generator set; determining a reference angular velocity of a motor of the flywheel energy storage system according to the reference power; acquiring an actual angular velocity of the motor; determining a rotational speed error according to the reference angular velocity and the actual angular velocity; determining an integral sliding mode surface corresponding to the rotational speed error; controlling the motor of the flywheel energy storage system according to the rotational speed error and the integral sliding mode surface to smooth the output power of the generator set; the controlling the motor of the flywheel energy storage system according to the rotational speed error and the integral sliding mode surface to smooth the output power of the generator set comprises: determining a system output of the motor through a preset improved exponential reaching law equation according to the rotational speed error and the integral sliding mode surface, the system output being a quadrature axis component of a stator current of the motor, the quadrature axis being a coordinate axis perpendicular to a rotor magnetic field direction in a rotor coordinate system of the motor; controlling the motor of the flywheel energy storage system according to the system output to smooth the output power of the generator set; the improved exponential reaching law equation comprises: wherein, , , , are constants greater than 0, e is the natural constant, s is the integral sliding surface, is the angular velocity error.

2. The method of claim 1, wherein, the acquiring the reference power of the flywheel energy storage system comprises: acquiring an output power reference value of the generator set and the flywheel energy storage system; acquiring a generated power actually generated by the generator set; determining the reference power of the flywheel energy storage system according to the output power reference value and the generated power.

3. The method of claim 1, wherein, the determining the reference angular velocity of the motor of the flywheel energy storage system according to the reference power comprises: determining a reference stored energy of the flywheel energy storage system according to the reference power; determining the reference angular velocity according to the reference stored energy and a preset moment of inertia of a flywheel rotor of the flywheel energy storage system.

4. The method according to any one of claims 1 to 3, characterized in that, Before the acquiring the reference power of the flywheel energy storage system, the method further comprises: acquiring rotational speed information of the motor; the acquiring the reference power of the flywheel energy storage system comprises: in a case where the rotational speed information is greater than or equal to a preset grid-connected rotational speed threshold value, acquiring the reference power of the flywheel energy storage system.

5. The method of claim 4, wherein, The method further comprises: in a case where the rotational speed information is less than the preset grid-connected rotational speed threshold value, acquiring rotor position and weighted rotational speed information of the motor according to the rotational speed information; initializing energy storage of the flywheel energy storage system according to a preset motor target rotational speed, the rotor position and the weighted rotational speed information, until re-acquired rotational speed information is greater than or equal to the grid-connected rotational speed threshold value.

6. The method of claim 5, wherein, the acquiring rotor position and weighted rotational speed information of the motor according to the rotational speed information comprises: in a case where the rotational speed information is less than or equal to a preset first rotational speed threshold value, determining rotor position and weighted rotational speed information of the motor through an algorithm of injecting a high-frequency pulsating current signal, the first rotational speed threshold value being less than the grid-connected rotational speed threshold value; or, In a case that the rotation speed information is greater than or equal to a preset second rotation speed threshold, the rotor position and the weighted rotation speed information of the motor are determined by an algorithm of an unscented Kalman filter, the second rotation speed threshold being greater than the first rotation speed threshold and less than the network access rotation speed threshold; or In a case that the rotation speed information is greater than the first rotation speed threshold and less than the second rotation speed threshold, the rotor position and the weighted rotation speed information of the motor are determined by an algorithm combining an injected high-frequency pulsating current signal and the unscented Kalman filter.

7. A device for controlling a flywheel energy storage system, characterized in that, The device comprises: The acquisition module is configured to acquire a reference power of a flywheel energy storage system, the reference power including a demand power for smoothing output power of a generator set; determine a reference angular velocity of a motor of the flywheel energy storage system according to the reference power; and acquire an actual angular velocity of the motor; The determination module is configured to determine a rotation speed error according to the reference angular velocity and the actual angular velocity; and determine an integral sliding mode surface corresponding to the rotation speed error; The control module is configured to control the motor of the flywheel energy storage system according to the rotation speed error and the integral sliding mode surface, so as to smooth the output power of the generator set; The control of the motor of the flywheel energy storage system according to the rotation speed error and the integral sliding mode surface, so as to smooth the output power of the generator set, comprises: determining a system output of the motor by a preset improved exponential approach rate equation according to the rotation speed error and the integral sliding mode surface, the system output being a quadrature axis component of a stator current of the motor, the quadrature axis being a coordinate axis perpendicular to a rotor magnetic field direction in a rotor coordinate system of the motor; controlling the motor of the flywheel energy storage system according to the system output, so as to smooth the output power of the generator set; The improved exponential approach rate equation comprises: wherein, , , , are constants greater than 0, e is the natural constant, s is the integral sliding surface, is the angular velocity error.

8. An electronic device, comprising: comprises: a memory having a computer program stored thereon; a processor configured to execute the computer program in the memory, so as to implement the steps of the method in any one of claims 1-6.

9. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The program, when executed by the processor, implements the steps of the method in any one of claims 1-6. The program, when executed by the processor, implements the steps of the method in any one of claims 1-6.

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