Flywheel energy storage frequency modulation and phase modulation system

Abstract

The application provides a flywheel energy storage frequency modulation and phase modulation system, and belongs to the technical field of power grid stability control. The flywheel is connected with the inner rotor of an electromagnetic coupler; the outer rotor of the electromagnetic coupler is connected with the rotor of a synchronous generator; the stator winding of the synchronous generator is connected with a power grid; the outer rotor winding of the electromagnetic coupler is connected with the power grid through a converter; an active power controller controls the active power of the synchronous generator by controlling the input torque of the rotor of the synchronous generator; and a reactive power controller controls the reactive power of the synchronous generator by controlling the excitation voltage of the synchronous generator. The flywheel and the synchronous generator are connected through the electromagnetic coupler, independent control of active power and reactive power of the system is realized, the power grid frequency and voltage are simultaneously supported and reactive power compensation effect is achieved, frequency modulation and phase modulation functions are realized; in addition, equivalent damping, equivalent inertia and primary frequency modulation control functions are added in the active power control, and the frequency modulation capacity of the system to the power grid is optimized.

Description

Technical Field

[0001] This invention relates to the field of power grid stability control technology, specifically to a flywheel energy storage frequency and phase regulation system. Background Technology

[0002] A synchronous condenser is a type of synchronous generator operating under special conditions. When applied to a power system, it can provide reactive power support to maintain voltage, improve power system stability, and enhance power supply quality. Flywheel energy storage technology is an emerging energy storage technology that stores kinetic energy through a high-speed rotating rotor in a low-friction environment. It features high power, fast response, high frequency, and long lifespan, and has broad application prospects.

[0003] Existing synchronous condensers mainly utilize their reactive power support to support grid voltage. Simultaneously, the kinetic energy stored in their rotors helps improve the overall inertia of the power system, thus also having a positive effect on frequency stability. However, because the rotor inertia of synchronous condensers is too low, they cannot provide sufficient inertia support to the grid. Furthermore, the active power they generate is uncontrollable, therefore they cannot achieve the function of frequency regulation for the grid. Summary of the Invention

[0004] The purpose of this invention is to provide a flywheel energy storage frequency and phase modulation system to solve at least one of the technical problems existing in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a flywheel energy storage frequency and phase modulation system, comprising:

[0007] A flywheel energy storage system, in which the flywheel is connected to the inner rotor of an electromagnetic coupler;

[0008] The outer rotor of the electromagnetic coupler is connected to the rotor of the synchronous generator;

[0009] The stator winding of the synchronous generator is connected to the power grid, and the outer rotor winding of the electromagnetic coupler is connected to the power grid through a converter;

[0010] An active power controller is used to control the active power of the synchronous generator by controlling the input torque of the rotor of the synchronous generator, thereby adjusting the active power input to the power grid.

[0011] A reactive power controller is used to control the reactive power of the synchronous generator by controlling the excitation voltage of the synchronous generator, thereby adjusting the reactive power input to the power grid.

[0012] Optionally, a gearbox can be connected in series between the outer rotor of the electromagnetic coupler and the rotor of the synchronous generator, or between the flywheel and the inner rotor of the electromagnetic coupler, to change the speed range of the flywheel.

[0013] Optionally, the active power controller includes an outer loop control unit and an inner loop control unit; the outer loop control unit is used to output the torque setpoint for controlling active power, the torque setpoint for controlling flywheel speed, the torque setpoint for controlling moment of inertia, the torque setpoint for controlling damping, and the torque setpoint for controlling primary frequency regulation, which are superimposed to obtain the total torque setpoint; the inner loop control unit is used to control the torque of the outer rotor of the electromagnetic coupler by controlling the current of the outer rotor of the electromagnetic coupler through the converter, so that it reaches the torque setpoint.

[0014] Optionally, the outer loop control unit includes active power outer loop control, speed outer loop control, moment of inertia outer loop control, damping outer loop control, and primary frequency regulation outer loop control; the active power outer loop control is used to output a torque setpoint for controlling active power, the speed outer loop control is used to output a torque setpoint for controlling flywheel speed, the moment of inertia outer loop control is used to control the equivalent moment of inertia of the synchronous generator, the damping outer loop control is used to dampen the speed of the synchronous generator, and the primary frequency regulation control is used to perform primary frequency regulation of the power grid.

[0015] Optionally, the active power outer loop control employs a combination of feedforward control and feedback control, with the output being the torque setpoint for controlling the active power; wherein, the feedforward control is... ωn represents the rated or actual speed of the synchronous generator, and the input to the feedback control is the difference between the given value and the measured value of the active power of the synchronous generator.

[0016] Optionally, the outer loop speed control adopts feedback control, with the input being the difference between the given speed and the actual speed of the flywheel, and the output being the torque setpoint for controlling the flywheel speed.

[0017] Optionally, the outer loop control unit for rotational inertia includes measuring the rotor speed of the synchronous generator, differentiating the speed signal, multiplying it by the equivalent inertia value, and then inverting the result to obtain a given electromagnetic torque value for achieving the equivalent inertia of the electromagnetic coupler. The torque of the electromagnetic coupler is then controlled by controlling the current of the outer rotor via a converter connected to the outer rotor winding of the electromagnetic coupler, thereby achieving the given value. To prevent amplification of high-frequency noise, a low-pass filter can be added to the differential signal to filter out high-frequency noise. To prevent frequent charging and discharging of the flywheel under normal conditions, which could affect its lifespan, the normal speed range can be set as a dead zone, and this function will not be activated within the dead zone.

[0018] Optionally, the damping outer loop control unit includes measuring the synchronous generator rotor speed, multiplying the speed signal by a damping coefficient and inverting the result to obtain a given electromagnetic torque value for achieving equivalent damping of the electromagnetic coupler. The torque of the electromagnetic coupler is then controlled by controlling the current of the outer rotor via a converter connected to the outer rotor winding of the electromagnetic coupler, thereby achieving the given value. To remove the influence of the DC component, the speed signal can either be filtered by a high-pass filter or by subtracting the rated speed. To prevent frequent charging and discharging of the flywheel under normal conditions, which could affect its lifespan, the normal speed range can be set as a dead zone, and this function can be disabled within the dead zone.

[0019] Optionally, the primary frequency modulation outer loop control unit includes a control unit using the grid frequency ω. g Subtract the rated frequency ω0 of the power grid and then multiply by a coefficient. (where D) p ω is the droop coefficient. n The rated or actual speed of the synchronous generator (Δω is the speed difference between the inner and outer rotors of the electromagnetic coupler) is inverted and used as the given electromagnetic torque value for primary frequency regulation of the electromagnetic coupler. The torque of the outer rotor is then controlled by controlling the current of the outer rotor through a converter connected to the outer rotor winding of the electromagnetic coupler, thus achieving the given value. To prevent primary frequency regulation from being activated within the normal frequency range, the normal frequency range can be set as a dead zone, and primary frequency regulation will not be activated within the dead zone.

[0020] Optionally, the reactive power controller includes a stator voltage amplitude controller and a reactive power controller. The input of the stator voltage amplitude controller is the difference between the setpoint and the measured value of the stator voltage amplitude, and the output is the excitation voltage for controlling the stator voltage. The input of the reactive power controller is the difference between the setpoint and the measured value of the reactive power, and the output is the excitation voltage for controlling the reactive power. The excitation voltage for controlling the stator voltage and the excitation voltage for controlling the reactive power are selectable; when stator voltage control is required, the excitation voltage for controlling the stator voltage is selected; when reactive power control is required, the excitation voltage for controlling the reactive power is selected.

[0021] Optionally, the reactive power controller includes stator voltage reactive power outer loop control and excitation current inner loop control. The stator voltage reactive power outer loop control includes a stator voltage amplitude controller and a reactive power controller. The input of the stator voltage amplitude controller is the difference between the setpoint and the measured value of the stator voltage amplitude, and the output is the setpoint of the excitation current for controlling the stator voltage. The input of the reactive power controller is the difference between the setpoint and the measured value of the reactive power, and the output is the setpoint of the excitation current for controlling the reactive power. The setpoints of the excitation current for controlling the stator voltage and the setpoints of the excitation current for controlling the reactive power are mutually exclusive. When stator voltage control is required, the setpoint of the excitation current for controlling the stator voltage is selected; when reactive power control is required, the setpoint of the excitation current for controlling the reactive power is selected. The input of the excitation current inner loop controller is the setpoint and the measured value of the excitation current, and the output is the excitation voltage of the synchronous generator.

[0022] The beneficial effects of this invention are as follows: It adopts a new structure that connects the flywheel and the synchronous generator through an electromagnetic coupler, so as to realize the independent control of active and reactive power of the system, achieve the effect of simultaneously supporting the frequency and voltage of the power grid and reactive power compensation, and realize the functions of frequency regulation and phase regulation; in addition, it adds equivalent damping, equivalent inertia links and primary frequency regulation control functions to the active power control, thereby optimizing the system's frequency regulation capability of the power grid.

[0023] The advantages of additional aspects of the invention will be set forth more clearly in the following description or will be learned by practice of the invention. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of synchronous condenser grid connection in existing technology.

[0026] Figure 2 This is a schematic diagram of the flywheel energy storage frequency and phase modulation system according to an embodiment of the present invention.

[0027] Figure 3 This is a block diagram illustrating the active power and flywheel speed control principle according to an embodiment of the present invention.

[0028] Figure 4 This is a block diagram illustrating the reactive power and voltage support single closed-loop control principle according to an embodiment of the present invention.

[0029] Figure 5 This is a block diagram illustrating the dual closed-loop control principle of reactive power and voltage support as described in an embodiment of the present invention. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as here.

[0033] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.

[0034] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0035] To facilitate understanding of the present invention, the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0036] Those skilled in the art should understand that the accompanying drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0037] Example 1

[0038] In this embodiment 1, a flywheel frequency and phase modulation system is provided, comprising: mechanically connecting the flywheel to the rotor of the synchronous generator through an electromagnetic coupler and a gearbox; the outer rotor winding of the electromagnetic coupler is connected to the power grid through a converter; and the stator winding of the synchronous generator is directly connected to the power grid; using the converter to control the torque of the electromagnetic coupler to indirectly control the mechanical torque output by the flywheel to the synchronous generator, thereby achieving control of the active power of the synchronous generator; and simultaneously controlling the reactive power of the synchronous generator by adjusting the excitation voltage of the synchronous generator, thereby achieving reactive power compensation and grid voltage support functions.

[0039] In this embodiment, the specific structure of the system is as follows: the system consists of a flywheel energy storage system, an electromagnetic coupler, a gearbox, and a synchronous generator. The connection method is as follows: the flywheel in the flywheel energy storage system can be directly connected to the inner rotor of the electromagnetic coupler, or it can be connected through the gearbox; the outer rotor of the electromagnetic coupler can be directly connected to the rotor of the synchronous generator, or it can be connected to the rotor of the synchronous generator through the gearbox; the stator winding of the synchronous generator is directly connected to the power grid, and the outer rotor winding of the electromagnetic coupler is connected to the power grid through a converter.

[0040] The active power of a synchronous generator is achieved by controlling the input torque of the synchronous generator rotor. The active power controller consists of two parts: an outer loop and an inner loop.

[0041] The structure of the active power outer loop is as follows:

[0042] The active power outer loop controller includes an active power outer loop, a speed outer loop, a moment of inertia control outer loop, a damping control outer loop, and a primary frequency regulation outer loop. The active power outer loop adopts a feedforward + feedback control scheme, while the speed outer loop adopts a feedback control scheme.

[0043] The outer loop of the rotational inertia control is implemented as follows: The rotor speed of the synchronous generator is measured. The speed signal is differentiated, multiplied by the equivalent inertia coefficient, and then inverted. This result serves as the given electromagnetic torque value for achieving the equivalent inertia of the electromagnetic coupler. The torque of the outer rotor is then controlled by controlling the current in the outer rotor via a converter connected to the outer rotor winding of the electromagnetic coupler, thus achieving the given value. To prevent amplification of high-frequency noise, a low-pass filter can be added to the differentiated signal to filter out high-frequency noise. To prevent frequent charging and discharging of the flywheel under normal conditions, which could affect its lifespan, the normal speed range can be set as a dead zone, and this function will not be activated within the dead zone.

[0044] The damping control outer loop is implemented as follows: The rotor speed of the synchronous generator is measured, and the speed signal is multiplied by the damping coefficient and inverted. This inverted value serves as the given electromagnetic torque value for achieving equivalent damping in the electromagnetic coupler. The torque of the outer rotor is then controlled by controlling the current in the outer rotor via a converter connected to the outer rotor winding of the electromagnetic coupler, thus achieving the given value. To remove the DC component, the speed signal can be either filtered using a high-pass filter or by subtracting the rated speed. To prevent frequent charging and discharging of the flywheel under normal conditions, which could affect its lifespan, the normal speed range can be set as a dead zone, and this function is not activated within the dead zone.

[0045] The outer loop of a single frequency modulation is implemented as follows: using the grid frequency ω g Subtract the rated frequency ω0 of the power grid and then multiply by a coefficient. (where D) p ω is the droop coefficient. n The rated or actual speed of the synchronous generator (Δω is the speed difference between the inner and outer rotors of the electromagnetic coupler) is inverted and used as the given electromagnetic torque value for primary frequency regulation of the electromagnetic coupler. The torque of the outer rotor is then controlled by controlling the current of the outer rotor through a converter connected to the outer rotor winding of the electromagnetic coupler, thus achieving the given value. To prevent primary frequency regulation from being activated within the normal frequency range, the normal frequency range can be set as a dead zone, and primary frequency regulation will not be activated within the dead zone.

[0046] The torque setpoints for controlling active power, flywheel speed, moment of inertia, damping, and primary frequency regulation output by the outer loop of the active power controller can be superimposed, enabling the active power controller to simultaneously control active power, flywheel speed, equivalent moment of inertia, equivalent damping, and primary frequency regulation.

[0047] The structure of the active inner loop is as follows:

[0048] The input to the active inner loop is the difference between the torque setpoint output from the outer loop and the measured torque of the electromagnetic coupler. The output of the active inner loop is the q-axis voltage U of the outer rotor of the electromagnetic coupler. eq ;

[0049] The reactive power control of this system is achieved by controlling the excitation voltage of the synchronous generator, and can employ both single-loop and double-loop control methods. In the single-loop mode, the controller consists of two parts: a stator voltage amplitude controller and a reactive power controller. The excitation voltages output by these two controllers are mutually exclusive; when stator voltage control is required, the excitation voltage controlling the stator voltage is selected; when reactive power control is required, the excitation voltage controlling the reactive power is selected. In the double-loop mode, the controller consists of two parts: a voltage-reactive power outer loop and an excitation current inner loop. The voltage-reactive power outer loop further comprises two parts: a stator voltage amplitude controller, whose input is the difference between the setpoint and measured stator voltage, and whose output is the setpoint excitation current for controlling the stator voltage; and a reactive power controller, whose input is the difference between the setpoint and measured reactive power, and whose output is the setpoint excitation current for controlling the reactive power. The excitation current setpoint for controlling stator voltage and the excitation current setpoint for controlling reactive power are mutually exclusive. When stator voltage needs to be controlled, the excitation current setpoint for controlling stator voltage is selected; when reactive power needs to be controlled, the excitation current setpoint for controlling reactive power is selected. The inner loop of the excitation current then makes the measured value of the excitation current track the setpoint. Its input is the difference between the excitation current setpoint and the measured value, and the output is the excitation voltage.

[0050] Example 2

[0051] Existing traditional synchronous condenser grid connection methods, such as Figure 1 As shown, it can only send reactive power to the power grid and lacks active power support capability.

[0052] like Figure 2 As shown, this embodiment 2 provides a frequency and phase modulation system. The flywheel is connected to the inner rotor of the electromagnetic coupler, the outer rotor of the electromagnetic coupler is connected to the rotor of the synchronous generator through a gearbox, the outer rotor winding of the electromagnetic coupler is connected to the power grid through a converter, and the stator winding of the synchronous generator is connected to the power grid.

[0053] Active power control methods such as Figure 3 As shown in the figure, P ref P and ω represent the given and measured values ​​of the active power output of the synchronous generator, respectively. n U is the rated or actual speed of the synchronous generator. eq ω is the q-axis voltage of the external rotor of the electromagnetic coupler. ref and ω f Given the given speed and actual speed of the flywheel, T e For the output torque of the electromagnetic coupler, ω ms J is the rotor speed of the synchronous generator. s and B s J represents the moment of inertia and coefficient of friction of a synchronous generator. f and Bf G represents the moment of inertia and coefficient of friction of the flywheel. T G is the transfer function from the external rotor q-axis voltage to the output torque of the electromagnetic coupler. ωp K is the transfer function between the speed and power of a synchronous generator. D J is the equivalent damping coefficient. e D is the equivalent inertia value. p Δω is the droop coefficient used for primary frequency regulation, Δω is the speed difference between the inner and outer rotors of the electromagnetic coupler, s is the Laplace operator, and ω g ω0 and ω0 are the actual frequency and rated frequency of the power grid, respectively.

[0054] The controller can be divided into two parts: an inner loop and an outer loop. The outer loop controller includes an active power outer loop, a speed outer loop, a moment of inertia control outer loop, a damping control outer loop, and a primary frequency regulation outer loop. The specific scheme is as follows:

[0055] The structure of the active power outer loop is as follows:

[0056] The controller adopts a feedforward + feedback scheme, with the feedforward controller being... The feedback controller is a PID (proportional-integral-derivative) controller, and its input is the given value P of the active power of the synchronous generator. ref The difference between the measured value P and the actual value P is output as the torque setpoint for controlling the active power.

[0057] The outer loop of the speed control uses a PID controller, with the input being the given speed ω of the flywheel. ref and actual rotational speed ω f The difference is output as the torque setpoint for controlling the flywheel speed.

[0058] The method for implementing the inertia control outer loop is as follows: measuring the rotor speed ω of the synchronous generator. ms , the rotational speed signal ω ms After differentiation (ω) ms s) multiplied by the equivalent inertia value J e The value is then inverted to obtain the given electromagnetic torque value for achieving the equivalent inertia of the electromagnetic coupler. The torque of the electromagnetic coupler is then controlled by controlling the current in the outer rotor via a converter connected to the outer rotor winding, thus achieving this given value. To prevent amplification of high-frequency noise, a low-pass filter can be added to the differential signal to filter out high-frequency noise. To prevent frequent charging and discharging of the flywheel under normal conditions, which could affect its lifespan, the normal speed range can be set as a dead zone, and this function will not be activated within the dead zone.

[0059] The method for implementing the damping control outer loop is as follows: measuring the synchronous generator rotor speed ω. ms Using the rotational speed signal ω ms Multiply by the damping coefficient K DThe value is then inverted to obtain the given electromagnetic torque value for achieving equivalent damping in the electromagnetic coupler. The torque of the electromagnetic coupler is then controlled by controlling the current in the outer rotor via a converter connected to the outer rotor winding of the electromagnetic coupler, thus achieving this given value. To remove the DC component, the speed signal can either be filtered by adding a high-pass filter or by subtracting the rated speed. To prevent frequent charging and discharging of the flywheel under normal conditions, which could affect its lifespan, the normal speed range can be set as a dead zone, and this function will not be activated within the dead zone.

[0060] The method for implementing the primary frequency modulation outer loop is as follows: using the actual grid frequency ω g Subtract the rated frequency ω0 of the power grid and then multiply by a coefficient. The value is then inverted and used as the given torque value for primary frequency regulation of the electromagnetic coupler. The torque of the electromagnetic coupler is then controlled by controlling the current of the outer rotor via a converter connected to the outer rotor winding, thus achieving this given value. To prevent primary frequency regulation from being activated within the normal frequency range, the normal frequency range can be set as a dead zone, and primary frequency regulation will not be activated within the dead zone.

[0061] The total torque setpoint T is obtained by superimposing the torque setpoints for controlling active power, flywheel speed, moment of inertia, damping, and primary frequency regulation. ref .

[0062] The structure of the active inner loop is as follows:

[0063] The active power inner loop uses a PID controller, and the input of the active power inner loop is the torque setpoint T output by the outer loop. ref Measured value T of electromagnetic coupler torque e The difference is that the output of the active inner loop is the q-axis voltage U of the outer rotor of the electromagnetic coupler. eq .

[0064] In this embodiment, reactive power control can employ either a single closed-loop or a double closed-loop method. The single closed-loop method is as follows: Figure 4 As shown in the figure, U ref U represents the given and measured values ​​of the stator voltage amplitude, and Q represents the measured value. ref Q and V represent the given and measured values ​​of the reactive power of the synchronous generator, respectively. fd G is the excitation voltage. VU G is the transfer function between the excitation voltage and the stator voltage amplitude of the synchronous generator. VQ Let I be the transfer function between the excitation voltage and the reactive power output of the synchronous generator. ref and I fdThe inputs are the given and measured values ​​of the excitation current. The controller consists of two parts: the first part is the stator voltage amplitude controller, which uses a PID controller, and its input is the given value U of the stator voltage amplitude. ref The difference between the measured value U and the output is the excitation voltage that controls the stator voltage; the second part is the reactive power controller, which uses a PID controller, and its input is the given value Q of reactive power. ref The difference between the measured value Q and the output is the excitation voltage for controlling reactive power. The excitation voltage for controlling stator voltage and the excitation voltage for controlling reactive power are mutually exclusive. When stator voltage needs to be controlled, the excitation voltage for controlling stator voltage is selected; when reactive power needs to be controlled, the excitation voltage for controlling reactive power is selected.

[0065] Dual closed-loop method such as Figure 5 As shown, the controller consists of two parts: a stator voltage reactive power outer loop and an excitation current inner loop. The stator voltage reactive power outer loop comprises two parts. The first part is the stator voltage amplitude controller, which employs a PID controller. Its input is the setpoint U of the stator voltage amplitude. ref The difference between the measured value U and the output value is the excitation current setpoint for controlling the stator voltage; the second part is the reactive power controller, which uses a PID controller, and its input is the reactive power setpoint Q. ref The difference between the measured value Q and the actual value Q is output as the excitation current setpoint for controlling reactive power. The excitation current setpoint for controlling stator voltage and the excitation current setpoint for controlling reactive power are mutually exclusive; when stator voltage control is required, the excitation current setpoint for stator voltage control is selected; when reactive power control is required, the excitation current setpoint for reactive power control is selected. G IU and G IQ These are the transfer functions between the excitation current and the stator voltage amplitude of the synchronous generator, and between the excitation current and the reactive power of the synchronous generator, respectively. The inner loop controller for the excitation current uses a PID controller, and its input is the given value I of the excitation current. ref and measured value I fd The difference is such that its output is the excitation voltage V of the synchronous generator. fd .

[0066] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions disclosed in the present invention, various modifications or variations that can be made by those skilled in the art without creative effort should be included within the scope of protection of the present invention.

Claims

1. A flywheel energy storage frequency modulation and phase modulation system, characterized in that, The application relates to a flywheel energy storage system, a flywheel in the flywheel energy storage system being connected with an inner rotor of an electromagnetic coupler; an outer rotor of the electromagnetic coupler being connected with a rotor of a synchronous generator; a stator winding of the synchronous generator being connected with a power grid; an outer rotor winding of the electromagnetic coupler being connected with the power grid through a converter; an active power controller being used for controlling active power of the synchronous generator by controlling input torque of the rotor of the synchronous generator, so as to adjust active power input to the power grid; the active power controller comprising an inner loop control unit and an outer loop control unit; the outer loop control unit being used for outputting torque given values for controlling active power, torque given values for controlling flywheel speed, torque given values for controlling moment of inertia, torque given values for controlling damping and torque given values for controlling primary frequency modulation; the torque given values for controlling active power, the torque given values for controlling flywheel speed, the torque given values for controlling moment of inertia, the torque given values for controlling damping and the torque given values for controlling primary frequency modulation being superposed to form a total torque given value; the inner loop control unit being used for controlling torque of the outer rotor of the electromagnetic coupler by controlling current of the outer rotor of the electromagnetic coupler through the converter, so as to make the torque reach the torque given value; a reactive power controller being used for controlling reactive power of the synchronous generator by controlling excitation voltage of the synchronous generator, so as to adjust reactive power input to the power grid. The outer loop control unit comprises active power outer loop control, speed outer loop control, moment of inertia outer loop control, damping outer loop control and primary frequency modulation outer loop control; the active power outer loop control is used for outputting torque given values for controlling active power; the speed outer loop control is used for outputting torque given values for controlling flywheel speed; the moment of inertia outer loop control is used for controlling equivalent moment of inertia of the synchronous generator; the damping outer loop control is used for damping speed of the synchronous generator; and the primary frequency modulation outer loop control is used for primary frequency modulation of the power grid frequency. The speed outer loop control adopts feedback control, the input being a difference between given speed and actual speed of the flywheel, and the output being torque given values for controlling flywheel speed. The inner loop control unit comprises measuring rotor speed of the synchronous generator, multiplying the speed signal by an equivalent inertia value and taking the negative value as a given electromagnetic torque value for enabling the electromagnetic coupler to realize equivalent inertia, and then controlling torque of the electromagnetic coupler by controlling current of the outer rotor of the electromagnetic coupler through the converter connected with the outer rotor winding of the electromagnetic coupler, so as to make the torque reach the given value. The inner loop control unit comprises measuring rotor speed of the synchronous generator, multiplying the speed signal by a damping coefficient and taking the negative value as a given electromagnetic torque value for enabling the electromagnetic coupler to realize equivalent damping, and then controlling torque of the electromagnetic coupler by controlling current of the outer rotor of the electromagnetic coupler through the converter connected with the outer rotor winding of the electromagnetic coupler, so as to make the torque reach the given value. ​ 2. The flywheel energy storage frequency modulation and phase modulation system of claim 1, wherein, ​ 3. The flywheel energy storage frequency modulation and phase modulation system of claim 2, wherein, The active power outer loop control adopts feedforward control combined with feedback control, and the output is a torque given value for controlling active power; wherein the feedforward control is , represents the rated or actual speed of the synchronous generator, and the input of the feedback control is the difference between the given value and the measured value of the active power of the synchronous generator.

4. The flywheel energy storage frequency modulation and phase modulation system of claim 2, wherein, ​ 5. The flywheel energy storage frequency modulation and phase modulation system of claim 1, wherein, ​ 6. The flywheel energy storage frequency modulation and phase modulation system of claim 1, wherein, ​ 7. The flywheel energy storage frequency modulation and phase modulation system of claim 1, wherein, The inner loop control unit comprises, with the grid frequency Subtract the grid rated frequency Post-multiply the coefficient Post-inversion, as a given electromagnetic torque value to make the electromagnetic coupler to achieve the first frequency modulation, and then through the current control of the outer rotor of the electromagnetic coupler by the converter connected with the outer rotor winding of the electromagnetic coupler to control the torque of the outer rotor of the electromagnetic coupler to reach the given value; wherein, D p is the droop coefficient, is the rated or actual speed of the synchronous generator, is the speed difference between the inner and outer rotors of the electromagnetic coupler.

8. The flywheel energy storage frequency modulation and phase modulation system of claim 1, wherein: The reactive power controller comprises a stator voltage amplitude controller and a reactive power controller, the input of the stator voltage amplitude controller being the difference between the given value and the measured value of the stator voltage amplitude, and the output being the excitation voltage for controlling the stator voltage; the input of the reactive power controller being the difference between the given value and the measured value of the reactive power, and the output being the excitation voltage for controlling the reactive power.

9. The flywheel energy storage frequency modulation and phase modulation system of claim 1, wherein: The reactive power controller comprises a stator voltage reactive power outer loop controller and an excitation current inner loop controller; the stator voltage reactive power outer loop controller comprises a stator voltage amplitude controller and a reactive power controller, the input of the stator voltage amplitude controller being the given value and the measured value of the stator voltage amplitude, and the output being the given value of the excitation current for controlling the stator voltage; the input of the reactive power controller being the given value and the measured value of the reactive power, and the output being the given value of the excitation current for controlling the reactive power; wherein the input of the excitation current inner loop controller is the given value and the measured value of the excitation current, and the output is the excitation voltage of the synchronous generator.

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