A control system and method for a thermal power unit and a flywheel energy storage to participate in grid frequency modulation, and a grid frequency modulation method

Abstract

This invention discloses a control system and method for the coordinated participation of thermal power units and flywheel energy storage in power grid frequency regulation, as well as a power grid frequency regulation method. This method abandons the low-pass filtering algorithm and uses a tracking differentiator to decompose the primary frequency regulation command of the thermal power unit. The decomposed low-frequency power component is allocated to the thermal power unit, while the high-frequency power component is allocated to the flywheel energy storage. This reduces the number of thermal power unit operations and output wear, extending the unit's lifespan. Furthermore, a gain coefficient that adaptively varies with the state of charge (SOC) and frequency deviation is introduced into the decomposed high-frequency power component, facilitating precise demand matching, improving energy utilization efficiency, better smoothing grid frequency fluctuations, and improving grid quality. Simultaneously, a Logistic function is introduced to constrain the theoretical output power of the flywheel energy storage, preventing deep charging and discharging of the flywheel and thus reducing flywheel losses.

Description

Technical Field

[0001] This invention belongs to the field of flywheel energy storage technology, and particularly relates to a control system and method for thermal power units and flywheel energy storage to participate in grid frequency regulation in a coordinated manner, as well as a grid frequency regulation method. Background Technology

[0002] As my country's traditional power system gradually transforms into a new type of power system, the proportion of renewable energy, represented by photovoltaic and wind power, is further increasing. However, the randomness and intermittency of renewable energy can easily cause instability in the grid frequency. Traditional thermal power units have disadvantages such as slow frequency regulation speed and low accuracy. Therefore, it is necessary to introduce new frequency regulation methods to solve a series of problems brought about by the large-scale grid connection of renewable energy.

[0003] Energy storage, as a key technology in the energy revolution, can ensure the stable operation of the power system. Among various energy storage methods, flywheel energy storage has significant advantages in frequency regulation due to its fast response and high charge / discharge cycles. Currently, some engineers have proposed a strategy of using flywheel energy storage to assist thermal power units in frequency regulation. This strategy can reduce the output of thermal power units on the one hand, and improve frequency regulation quality on the other, ensuring the safe and stable operation of the power grid on the other. However, this common strategy of using flywheel energy storage to assist thermal power units in frequency regulation generally uses a low-pass filter to decompose the primary frequency regulation command into high-frequency and low-frequency signals. This method is difficult to simultaneously address the smoothing of thermal power unit output fluctuations and the charging and discharging safety of the flywheel energy storage system. For example, an existing technology entitled "Flywheel Energy Storage Coupled with Thermal Power Unit Frequency Regulation Control Strategy under Multiple Operating Stages"... Figure 1 As shown, the low-pass filtering stage in this prior art uses a first-order Butterworth low-pass filter with a transfer function of T1 is the low-pass filter time constant, and the decomposed low-frequency signal P is... tpu =-K G ·Δf·G F (s), high-frequency signal P disf =-K G ·Δf·(1-G F (s)). The low-pass filtering algorithm used in this prior art has a fixed cutoff frequency and is simple to control, and the filtering function can only be achieved by adjusting the time constant. When faced with different input signals and application requirements, the fixed cutoff frequency cannot simultaneously meet the flexible separation of different frequency components. In a combined thermal power and energy storage system, facing different power deficits during frequency degradation and recovery periods, it is difficult to adaptively adjust according to specific application requirements to achieve the best filtering effect. Therefore, it cannot fully utilize the timeliness of "power-type" flywheel energy storage in responding to loads when frequency regulation commands change rapidly, or the stability of "energy-type" coal-fired power units in responding to loads when frequency regulation commands change slowly. At the same time, the fixed parameters cannot keep the flywheel within a reasonable operating range while ensuring the quality of grid frequency regulation.

[0004] In addition, most conventional flywheel energy storage strategies currently use droop control to directly determine the flywheel power, which cannot fully utilize the advantages of flywheel energy storage such as fast response and multiple charge and discharge cycles. Furthermore, this strategy has not effectively alleviated the life loss of thermal power units caused by frequent power output and severe wear. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a control system and method for thermal power units and flywheel energy storage to collaboratively participate in grid frequency regulation, as well as a grid frequency regulation method.

[0006] The technical solution of the present invention is as follows:

[0007] A control system for the coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation, wherein the thermal power units and flywheel energy storage are connected to the grid, includes a signal decomposition module, a thermal power unit actual power acquisition module, a flywheel energy storage actual power acquisition module, and a frequency regulation power output module;

[0008] The signal decomposition module is used to decompose the low-frequency power component and high-frequency power component of the primary frequency regulation command determined by the grid frequency deviation based on the tracking differentiator.

[0009] The actual power acquisition module of the thermal power unit is used to use the low-frequency power component as the reference power of the thermal power unit, and to acquire the actual power of the thermal power unit through the thermal power unit coordination and control system.

[0010] The flywheel energy storage actual power acquisition module is used to adaptively adjust the gain of the high-frequency power component based on the real-time changes in the flywheel energy storage state of charge and the grid frequency deviation to obtain the flywheel allocated power. Then, based on the flywheel allocated power, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical expected power of the flywheel energy storage. Next, the theoretical expected power of the flywheel energy storage is constrained by a Logistic regression function based on the flywheel energy storage state of charge and to prevent overcharging and over-discharging of the flywheel energy storage to obtain the reference power of the flywheel energy storage. Finally, the actual power of the flywheel energy storage is obtained through the flywheel energy storage control system, and the state of charge is monitored in real time based on the actual power of the flywheel energy storage to determine the state of charge of the flywheel energy storage.

[0011] The frequency regulation power output module is used to take the sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage as the frequency regulation power for the thermal power unit and the flywheel energy storage to participate in grid frequency regulation in a coordinated manner.

[0012] A control method for the coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation, wherein the grid is connected to thermal power units and flywheel energy storage, comprising:

[0013] Based on the tracking differentiator, the primary frequency regulation command determined by the grid frequency deviation is decomposed into low-frequency power components and high-frequency power components.

[0014] The low-frequency power component is used as the reference power of the thermal power unit, and the actual power of the thermal power unit is obtained through the thermal power unit coordination and control system.

[0015] The high-frequency power component is adaptively adjusted for changes in the flywheel energy storage state of charge and the real-time variation of the grid frequency deviation to obtain the flywheel allocated power. Based on the flywheel allocated power, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical expected power of the flywheel energy storage. The theoretical expected power of the flywheel energy storage is constrained by a Logistic regression function based on the flywheel energy storage state of charge and to prevent overcharging and over-discharging of the flywheel energy storage to obtain the reference power of the flywheel energy storage. The actual power of the flywheel energy storage is then obtained through the flywheel energy storage control system, and the state of charge of the flywheel energy storage is monitored in real time based on the actual power of the flywheel energy storage to determine the state of charge of the flywheel energy storage.

[0016] The sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage is used as the frequency regulation power for the thermal power unit and the flywheel energy storage to participate in grid frequency regulation in a coordinated manner.

[0017] Furthermore, the specific method for decomposing the low-frequency power component and high-frequency power component of the primary frequency regulation command determined by the grid frequency deviation includes:

[0018] The primary frequency regulation command P is determined by the grid frequency deviation. G ,

[0019] P G =-K G ×Δf

[0020] In the formula, K G Δf is the static characteristic coefficient of the power frequency of the thermal power unit; Δf is the system frequency deviation.

[0021] The primary frequency modulation command P is applied using a tracking differentiator. G The power components are decomposed to obtain low-frequency and high-frequency power components.

[0022]

[0023] In the formula, P T (k+1) and P T (k) represent the low-frequency power components at sampling times k+1 and k, respectively; P D (k+1) and P D (k) represents the high-frequency power components at sampling times k+1 and k, respectively; h is the sampling period; and fhan is the fastest control synthesis function.

[0024] Furthermore, the specific method for using the low-frequency power component as the reference power of the thermal power unit and obtaining the actual power of the thermal power unit through the thermal power unit coordination and control system is as follows:

[0025] P Gact =G en (s)*G ov (s)*P T

[0026] In the formula, P Gact G represents the actual power output of the thermal power unit. en (s) is the transfer function of the steam turbine; G ov (s) is the transfer function of the speed governor; P T This represents the low-frequency power component.

[0027] Furthermore, the specific method for obtaining the flywheel power distribution by adaptively adjusting the flywheel energy storage state of charge and the real-time changes in grid frequency deviation for the high-frequency power components includes:

[0028] Based on the real-time state of charge of the flywheel energy storage, the state of charge gain coefficient of the flywheel energy storage during charging and discharging is obtained.

[0029]

[0030] In the formula, K c and K d These are the state-of-charge gain coefficients for flywheel energy storage during charging and discharging, respectively; K0 is the initial gain coefficient; S soc For real-time energy storage state of charge, S SOCmax S SOCmin These are the maximum and minimum values ​​of the state of charge, respectively.

[0031] Based on real-time grid frequency deviation, the frequency deviation gain coefficient of flywheel energy storage is obtained.

[0032]

[0033] In the formula, α is the frequency deviation gain coefficient of flywheel energy storage; f d The right endpoint value of the frequency modulation dead zone; Δf m This represents the maximum system frequency deviation.

[0034] Based on the state-of-charge gain coefficient and frequency deviation gain coefficient of the flywheel energy storage during charging and discharging, the gain coefficient of the adaptive flywheel energy storage state of charge and grid frequency deviation is obtained.

[0035]

[0036] In the formula, KD The gain coefficient for adaptive flywheel energy storage state of charge changes and grid frequency deviation changes;

[0037] The flywheel power allocation is obtained by using the gain coefficients of the high-frequency power components and the real-time changes in the adaptive flywheel energy storage state of charge and grid frequency deviation.

[0038] P fast =K D ×P D

[0039] In the formula, P fast Distribute power to the flywheel; P D It represents the high-frequency power component.

[0040] Furthermore, based on the flywheel's allocated power, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical expected power of the flywheel energy storage. The theoretical expected power of the flywheel energy storage is then constrained by a Logistic regression function based on the flywheel's state of charge to prevent overcharging and over-discharging, resulting in a reference power for the flywheel energy storage. Finally, the specific method for obtaining the actual power of the flywheel energy storage through the flywheel energy storage control system includes:

[0041] Based on the grid frequency deviation, the flywheel energy storage droop control command is determined.

[0042] P f =-K f ×Δf

[0043] In the formula, P f For flywheel energy storage droop control commands; K f The power-frequency static characteristic coefficient of flywheel energy storage;

[0044] Based on the flywheel power distribution, the droop control command is adaptively corrected to obtain the theoretical expected power of the flywheel's energy storage.

[0045] P f ′=P fast +P f

[0046] In the formula, P f ′ represents the theoretical power output of the flywheel energy storage;

[0047] Based on the flywheel energy storage state of charge, the charging constraint power and discharging constraint power of the flywheel energy storage are obtained.

[0048]

[0049] In the formula, P c For charging-constrained power, P d For the discharge constraint power, P mRated power of the energy storage system; S SOCmax The maximum permissible state of charge; S SOCmin The minimum allowable state of charge; K, P, P0, B, and R are the first, second, third, fourth, and fifth constants, respectively;

[0050] Based on the charging constraint power and discharging constraint power of the flywheel energy storage, a reference power for the flywheel energy storage is obtained. This reference power includes the charging reference power P of the flywheel energy storage. fref,c and discharge reference power P fref,d ,

[0051]

[0052]

[0053] Finally, the actual power P of the flywheel energy storage system is obtained through equivalent analysis. fact ,

[0054] P fact =G F (s)P fref

[0055] In the formula, G F (s) is the transfer function of the flywheel energy storage control system after equivalent analysis; P fref The reference power for flywheel energy storage is P when the flywheel is charging. fref =P fref,c When the flywheel discharges, P fref =P fref,d .

[0056] Furthermore, the specific method for determining the state of charge of the flywheel energy storage by real-time monitoring based on the actual power of the flywheel energy storage includes:

[0057]

[0058] In the formula, S SOC State of charge of flywheel energy storage; S SOC0 The initial state of charge of the flywheel energy storage system is represented by E; the total energy storage capacity of the flywheel energy storage system is represented by E.

[0059] Furthermore, the specific method for using the sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage as the frequency regulation power for the thermal power unit and the flywheel energy storage to cooperate in grid frequency regulation includes:

[0060] P act =P fact +P Gact

[0061] In the formula, P actFrequency regulation power for thermal power units and flywheel energy storage to work together in grid frequency regulation.

[0062] A power grid frequency regulation method, wherein the power grid is connected to thermal power units and flywheel energy storage, comprising:

[0063] If the obtained grid frequency deviation falls outside the preset frequency regulation dead zone, then the thermal power unit and flywheel energy storage are controlled by the control method described above for the thermal power unit and flywheel energy storage to participate in grid frequency regulation in a coordinated manner, so as to adjust the grid frequency with the frequency regulation power of the thermal power unit and flywheel energy storage participating in grid frequency regulation in a coordinated manner.

[0064] Furthermore, the frequency modulation dead zone is in, This is the left endpoint value of the FM dead zone. This is the right endpoint value of the FM dead zone.

[0065] An electronic device includes a memory and a processor, the memory storing a computer program, the processor being configured to invoke and run the computer program stored in the memory to perform the method as described in any of the preceding methods.

[0066] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method described in any of the preceding claims.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] This invention proposes a control system and method for the coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation. This method abandons the low-pass filtering algorithm and uses a tracking differentiator to decompose the primary frequency regulation command of the thermal power unit. The decomposed low-frequency power component (signal) is allocated to the thermal power unit, while the high-frequency power component (signal) is allocated to the flywheel energy storage. This fully utilizes the flywheel's characteristics of fast response and high charge / discharge cycles, reducing the number of thermal power unit operations and output wear, and extending the unit's lifespan. Furthermore, a gain coefficient that adaptively varies with the state of charge (SOC) and frequency deviation is introduced into the decomposed high-frequency power component. This allows the high-frequency power classification to adaptively adjust according to changes in SOC and frequency regulation amplitude, facilitating precise demand matching, improving energy utilization efficiency, better smoothing grid frequency fluctuations, and improving grid quality. Simultaneously, a Logistic function is introduced to constrain the theoretical output power of the flywheel energy storage, preventing deep charging and discharging of the flywheel, thereby reducing flywheel losses and extending its service life.

[0069] This invention proposes a power grid frequency regulation method. This method, through the coordinated operation of flywheels and thermal power units, decomposes a primary frequency regulation command into low-frequency and high-frequency power components, which are then distributed to the thermal power units and flywheel energy storage units respectively, establishing a collaborative scheduling mechanism for the combined thermal and energy storage system. This strategy can fully leverage the "power-oriented" characteristics of the flywheel and the "energy-oriented" characteristics of thermal power, while simultaneously improving power quality and economic benefits. Attached Figure Description

[0070] Figure 1 The following is a system block diagram of the background technology that uses a low-pass filter to decompose a primary frequency modulation command into a signal;

[0071] Figure 2 This is a control principle diagram of the thermal power unit and flywheel energy storage working together to participate in grid frequency regulation in the embodiment;

[0072] Figure 3 This is a schematic diagram of the primary frequency modulation coordinated control principle in the embodiment;

[0073] Figure 4 This is a schematic diagram illustrating the signal decomposition principle of the tracking differentiator in the embodiment.

[0074] Figure 5 This is a control principle diagram of the flywheel energy storage unit in the embodiment;

[0075] Figure 6 This is a schematic diagram of the control method for the coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation in the embodiment;

[0076] Figure 7 This is a schematic diagram of the frequency deviation variation curves of different control strategies under step disturbance in Application Example 1.

[0077] Figure 8 This is a schematic diagram of the output power curves of thermal power units under different control strategies in the step disturbance application example 1.

[0078] Figure 9 This is a schematic diagram of the flywheel energy storage output power curves under different control strategies in the first application example of the step disturbance.

[0079] Figure 10 This is a schematic diagram of the frequency deviation variation curves of different control strategies under continuous disturbance in Application Example 2;

[0080] Figure 11 This is a schematic diagram of the output power curves of thermal power units under different control strategies in the second embodiment of the application of continuous disturbance;

[0081] Figure 12 This is a schematic diagram of the flywheel energy storage output power curves under different control strategies during continuous disturbance in Example 2. Detailed Implementation

[0082] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0083] Example 1:

[0084] This invention discloses a control system for the coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation, wherein thermal power units and flywheel energy storage are connected to the grid, such as... Figures 2-5 As shown, the system includes a signal decomposition module, a thermal power unit actual power acquisition module, a flywheel energy storage actual power acquisition module, and a frequency modulation power output and state of charge monitoring module.

[0085] The signal decomposition module is used to decompose the low-frequency power component and high-frequency power component of the primary frequency regulation command determined by the grid frequency deviation based on the tracking differentiator.

[0086] The thermal power unit actual power acquisition module is used to use the low-frequency power component as the reference power of the thermal power unit, and obtain the actual power of the thermal power unit through the thermal power unit coordination and control system.

[0087] The flywheel energy storage actual power acquisition module is used to adaptively adjust the gain of the high-frequency power component based on the real-time changes in the flywheel energy storage state of charge and the grid frequency deviation to obtain the flywheel allocated power. Then, based on the flywheel allocated power, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical expected power of the flywheel energy storage. Next, the theoretical expected power of the flywheel energy storage is constrained by a Logistic regression function based on the flywheel energy storage state of charge and to prevent overcharging and over-discharging of the flywheel energy storage to obtain the reference power of the flywheel energy storage. Finally, the actual power of the flywheel energy storage is obtained through the flywheel energy storage control system, and the state of charge of the flywheel energy storage is monitored in real time based on the actual power of the flywheel energy storage to determine the state of charge of the flywheel energy storage.

[0088] The frequency regulation power output module is used to take the sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage as the frequency regulation power for the thermal power unit and the flywheel energy storage to participate in grid frequency regulation in a coordinated manner.

[0089] Example 2:

[0090] This invention discloses a control method for the coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation, wherein thermal power units and flywheel energy storage are connected to the grid, such as... Figure 4 and Figure 6 As shown, the specific steps include the following:

[0091] S1. Based on the tracking differentiator, the primary frequency regulation command determined by the grid frequency deviation is decomposed into low-frequency power components and high-frequency power components.

[0092] S2. Use the low-frequency power component as the reference power of the thermal power unit, and obtain the actual power of the thermal power unit through the thermal power unit coordination and control system.

[0093] S3. Adapt the gain of the high-frequency power component to the real-time changes in the flywheel energy storage state of charge and grid frequency deviation to obtain the flywheel distribution power; based on the flywheel distribution power, adaptively correct the droop control command determined by the grid frequency deviation to obtain the theoretical expected power of the flywheel energy storage; constrain the theoretical expected power of the flywheel energy storage with a Logistic regression function based on the flywheel energy storage state of charge and to prevent overcharging and over-discharging of the flywheel energy storage to obtain the reference power of the flywheel energy storage; then obtain the actual power of the flywheel energy storage through the flywheel energy storage control system, and perform real-time state of charge monitoring based on the actual power of the flywheel energy storage to determine the flywheel energy storage state of charge;

[0094] S4. The sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage is used as the frequency regulation power for the thermal power unit and the flywheel energy storage to participate in the grid frequency regulation in a coordinated manner.

[0095] Example 3:

[0096] This embodiment is further designed based on embodiment two, as follows: Figure 3 As shown, the specific method for decomposing the low-frequency power component and high-frequency power component of the primary frequency regulation command determined by the grid frequency deviation in this example includes:

[0097] The primary frequency regulation command P is determined by the grid frequency deviation. G ,

[0098] P G =-K G ×Δf

[0099] In the formula, K G Δf is the static characteristic coefficient of the power frequency of the thermal power unit; Δf is the system frequency deviation.

[0100] A tracking differentiator is used to apply the primary frequency modulation command P. G The power components are decomposed to obtain low-frequency and high-frequency power components.

[0101]

[0102] In the formula, P T (k+1) and P T (k) represent the low-frequency power components at sampling times k+1 and k, respectively; P D (k+1) and P D(k) represents the high-frequency power components at sampling times k+1 and k, respectively; h is the sampling period; fhan is the fastest control synthesis function, and the expression of the fastest control synthesis function fhan is as follows:

[0103]

[0104] In the formula, r is the factor that determines the speed of tracking the input signal in the tracking differentiator; a is the first intermediate parameter; d is the second intermediate parameter; d0 is the third intermediate parameter; and δ is the fourth intermediate parameter.

[0105] Example 4:

[0106] This embodiment is further designed based on embodiment three, as follows: Figure 4 As shown in the example, the low-frequency power component is used as the reference power of the thermal power unit. The specific method for obtaining the actual power of the thermal power unit through the thermal power unit coordination and control system is as follows:

[0107] P Gact =G en (s)*G ov (s)*P T

[0108] In the formula, P Gact G represents the actual power output of the thermal power unit. en (s) is the transfer function of the steam turbine; G ov (s) is the transfer function of the speed governor; P T This represents the low-frequency power component.

[0109] Among them, the transfer function G of the steam turbine en The expression for (s) is:

[0110]

[0111] In the formula, F HP F IP F LP These are the power coefficients of the high-pressure, intermediate-pressure, and low-pressure cylinders of the steam turbine, respectively; T CH T RH T CO These are the volumetric time constants for high-pressure steam, reheat steam, and low-pressure steam, respectively.

[0112] The transfer function G of the speed governor ov The expression for (s) is:

[0113]

[0114] In the formula, T g This is the time constant of the speed controller.

[0115] Example 5:

[0116] This embodiment is further designed based on embodiment four, as follows: Figure 4 As shown, the specific method for obtaining the flywheel power distribution by adapting the gain of the flywheel energy storage state of charge and the real-time changes in grid frequency deviation to the high-frequency power components includes:

[0117] Based on the real-time state of charge of the flywheel energy storage, the state of charge gain coefficient of the flywheel energy storage during charging and discharging is obtained.

[0118]

[0119] In the formula, K c and K d These are the state-of-charge gain coefficients for flywheel energy storage during charging and discharging, respectively; K0 is the initial gain coefficient; S soc For real-time energy storage state of charge, S SOCmax S SOCmin These are the maximum and minimum values ​​of the state of charge, respectively.

[0120] Based on real-time grid frequency deviation, the frequency deviation gain coefficient of flywheel energy storage is obtained.

[0121]

[0122] In the formula, α is the frequency deviation gain coefficient of flywheel energy storage; f d This is the right endpoint value of the FM dead zone, typically taken as 0.033Hz; Δf m This represents the maximum system frequency deviation.

[0123] Based on the state-of-charge gain coefficient and frequency deviation gain coefficient of flywheel energy storage during charging and discharging, the gain coefficient of adaptive flywheel energy storage in real time changes with grid frequency deviation is obtained.

[0124]

[0125] In the formula, K D The gain coefficient for adaptive flywheel energy storage state of charge changes and grid frequency deviation changes;

[0126] The flywheel power allocation is obtained by adjusting the gain coefficients of the high-frequency power components and the real-time changes in the adaptive flywheel energy storage state of charge and grid frequency deviation.

[0127] P fast =K D ×P D

[0128] In the formula, P fast Distribute power to the flywheel; P D It represents the high-frequency power component.

[0129] Example 6:

[0130] This embodiment is further designed based on embodiment five, as follows: Figure 4 and Figure 5 As shown, in this example, based on the flywheel's power distribution, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical expected power of the flywheel energy storage. The theoretical expected power of the flywheel energy storage is then constrained by a Logistic regression function based on the flywheel's state of charge to prevent overcharging and over-discharging, resulting in a reference power for the flywheel energy storage. Finally, the specific method for obtaining the actual power of the flywheel energy storage through the flywheel energy storage control system includes:

[0131] Based on the grid frequency deviation, the flywheel energy storage droop control command is determined.

[0132] P f =-K f ×Δf

[0133] In the formula, P f For flywheel energy storage droop control commands; K f The power-frequency static characteristic coefficient of flywheel energy storage;

[0134] Based on the flywheel's power distribution, the droop control command is adaptively corrected to obtain the theoretical expected power of the flywheel's energy storage.

[0135] P f ′=P fast +P f

[0136] In the formula, P f ′ represents the theoretical power output of the flywheel energy storage;

[0137] Based on the state of charge of flywheel energy storage, the charging constraint power and discharging constraint power of flywheel energy storage are obtained.

[0138]

[0139] In the formula, P c For charging-constrained power, P d For the discharge constraint power, P m Rated power of the energy storage system; S SOCmax The maximum permissible state of charge; S SOCmin The minimum allowable state of charge; K, P, P0, B, and R are the first, second, third, fourth, and fifth constants, respectively;

[0140] Based on the charging and discharging constraint power of flywheel energy storage, a reference power for flywheel energy storage is obtained. This reference power includes the charging reference power P of the flywheel energy storage.fref,c and discharge reference power P fref,d ,

[0141]

[0142] Finally, the actual power P of the flywheel energy storage system is obtained through equivalent analysis. fact ,

[0143] P fact =G F (s)P fref

[0144] In the formula, G F (s) is the transfer function of the flywheel energy storage control system after equivalent analysis; P fref The reference power for flywheel energy storage is P when the flywheel is charging. fref =P fref,c When the flywheel discharges, P fref =P fref,d .

[0145] Example 7:

[0146] This embodiment, based on Embodiment Six, further designs the following: In this example, real-time state of charge monitoring is performed based on the actual power of the flywheel energy storage. The specific method for determining the state of charge of the flywheel energy storage includes:

[0147]

[0148] In the formula, S SOC State of charge of flywheel energy storage; S SOC0 The initial state of charge of the flywheel energy storage system is represented by E; the total energy storage capacity of the flywheel energy storage system is represented by E.

[0149] Example 8:

[0150] This embodiment, based on Embodiment Seven, further designs the following: The specific method for using the sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage as the frequency regulation power for the coordinated participation of the thermal power unit and flywheel energy storage in grid frequency regulation includes:

[0151] P act =P fact +P Gact

[0152] In the formula, P act Frequency regulation power for thermal power units and flywheel energy storage to work together in grid frequency regulation.

[0153] Example 9:

[0154] This invention provides a power grid frequency regulation method, wherein the power grid is connected to thermal power units and flywheel energy storage, such as... Figure 2As shown, it includes:

[0155] If the acquired grid frequency deviation falls outside a pre-set frequency regulation dead zone, then the thermal power unit and flywheel energy storage are controlled using the control method of the present invention for the coordinated participation of thermal power unit and flywheel energy storage in grid frequency regulation, adjusting the grid frequency with the frequency regulation power of the thermal power unit and flywheel energy storage participating in grid frequency regulation. If not, then neither the thermal power unit nor the flywheel energy storage participates in frequency regulation. The aforementioned pre-set frequency regulation dead zone can be... This is the left endpoint value of the FM dead zone. This is the right endpoint value of the FM dead zone, generally.

[0156] Example 10:

[0157] In this example, an electronic device includes a memory and a processor. The memory stores a computer program, and the processor is used to invoke and run the computer program stored in the memory to perform the methods of any of the above embodiments.

[0158] In this example, a computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of any of the above embodiments.

[0159] Application Example 1:

[0160] In this example, the control method and grid frequency regulation method of the present invention for the coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation are used to control a thermal power-storage combined system. The grid rated frequency is 50Hz, the rated power of the thermal power units in the thermal power-storage combined system is 800MW, and the specific parameters are shown in Table 1. The thermal power-storage combined system uses a 2MW / 0.05MWh flywheel unit, and the specific parameters are shown in Table 2.

[0161] Table 1 Simulation parameters of thermal power units

[0162] parameter numerical values <![CDATA[Governor time constant T g / s]]> 0.08 <![CDATA[The droop coefficient K of a thermal power unit G > 20 <![CDATA[High-pressure steam volume time constant T CH / s]]> 0.3 <![CDATA[Medium-pressure steam volume time constant T RH / s]]> 10 <![CDATA[Low-pressure steam volume time constant T CO / s]]> 0.5 <![CDATA[High-pressure cylinder power coefficient F HP > 0.3 <![CDATA[Medium pressure cylinder power coefficient F IP > 0.3 <![CDATA[Low-pressure cylinder power coefficient F LP > 0.4 Generator inertial constant H 5 Generator load damping coefficient D 1

[0163] Table 2 Flywheel Simulation Parameters

[0164] parameter numerical values <![CDATA[Stator resistance R s / Ω]]> 0.001506 Permanent magnet flux linkage ψf / Wb 0.318 Viscous friction coefficient B / (N·m / (rad / s)) 1100 Stator inductance L / mH 0.13 <![CDATA[Number of pole pairs n p > 1 <![CDATA[Flywheel moment of inertia J / (kg·m 2 )]]> 19.5

[0165] At t=1s, a 3MW step disturbance is added, and the simulation time is 30s. The maximum frequency deviation absolute value |Δf is used as the metric. max |, Absolute value of steady-state frequency deviation|Δf s |、and from|Δf max |to|Δf s |Time elapsed Δt s These are the evaluation indicators. The smaller the absolute value of each indicator, the better the frequency modulation effect.

[0166] The frequency deviation curves, thermal power unit output power curves, and flywheel output power curves obtained from simulations under different step disturbance strategies are shown below. Figures 7-9 As shown in Table 3, the calculations for each indicator are as follows:

[0167] Table 3 Frequency Evaluation Indicators under Step Disturbance

[0168] Control strategy <![CDATA[Δf max / Hz]]> <![CDATA[Δf s / Hz]]> <![CDATA[Δt s / s]]> No energy storage 0.05007 0.03980 23.492 Sagging control 0.03624 0.03024 18.236 Invention Strategy 0.03285 0.03005 16.025

[0169] As shown in Table 3, under step disturbance, the maximum absolute value of frequency deviation |Δf| under the method of the present invention is... max The method reduces energy consumption by 34.39% compared to a control strategy without energy storage and by 9.35% compared to a droop control strategy. The absolute value of the steady-state frequency deviation |Δf| is also shown in the figure. s |This reduces energy consumption by 24.50% compared to a control strategy without energy storage, and by 0.628% compared to a droop control strategy. Combined Figure 7 It can be seen that the transient and steady-state deviations of the system frequency are significantly reduced under the method of the present invention, the system frequency fluctuations are effectively reduced, and the stability is improved.

[0170] Depend on Figure 8 It can be seen that, under the same conditions, the steady-state output power of the thermal power unit decreased from 2.688MW without energy storage control strategy to 1.928MW. Although the steady-state value of the method of this invention is the same as that of the droop control strategy, the time taken to reach the steady-state value is shorter. Compared with other strategies, the method of this invention reduces the output power requirements of the thermal power unit during primary frequency regulation, and has a more significant effect on reducing the pressure of primary frequency regulation of thermal power.

[0171] Depend on Figure 9 As can be seen, when the frequency changes, the flywheel responds quickly under the method of the present invention, and the output power reaches its peak in a short time, releasing the stored electricity.

[0172] Application Example 2:

[0173] Application Example 1 illustrates that under step disturbance conditions, the method of the present invention can improve the overall frequency regulation effect. However, the frequency fluctuations that cause the unit to perform primary frequency regulation are generally caused by continuous, irregular, small-amplitude rapid load fluctuations. Therefore, this example performs simulation analysis on the method of the present invention and the corresponding comparative strategy under continuous disturbance.

[0174] In this example, a continuous small perturbation with an amplitude between [3,3] MW is added to the system, and the simulation time is set to 80 s. The frequency peak-to-valley difference Δf is used as the metric. p-v Standard deviation f of frequency deviation SD As evaluation indicators, the smaller the corresponding value of each indicator, the better the frequency modulation effect.

[0175]

[0176] In the formula, Δf i Let be the power grid frequency deviation at time i; N represents the average frequency deviation of the power grid under continuous disturbance; N is the total number of points used.

[0177] The frequency deviation curves, thermal power unit output power curves, and flywheel output power curves obtained from simulations under different strategies for continuous load disturbances are shown below. Figure 10-12 The calculation of its indicators is shown in Table 4:

[0178] Table 4 Frequency Evaluation Indicators under Continuous Disturbance

[0179] Control strategy <![CDATA[Δf p-v / Hz]]> <![CDATA[f SD / Hz]]> No energy storage 0.3183 0.0577 Sagging control 0.2664 0.0471 Invention Strategy 0.1924 0.0385

[0180] As shown in Table 4, under continuous load disturbance, the frequency peak-to-valley difference Δf under the method of the present invention... p–v Compared to a control strategy without energy storage, the frequency fluctuation is reduced by 39.55%, and compared to a droop control strategy, it is reduced by 27.78%. This demonstrates that the method of the present invention can effectively reduce system frequency fluctuations. The frequency deviation fluctuation index f of the method of the present invention... SD It reduces energy consumption by 33.28% compared to control strategies without energy storage and by 18.26% compared to droop control. Combined with... Figure 10 As can be seen, the frequency fluctuation curve of the system under the control strategy presented in this paper is more stable and has a smaller fluctuation amplitude compared with other control strategies, which significantly improves the performance of maintaining frequency stability.

[0181] Depend on Figure 11 It can be seen that the power output fluctuation of thermal power units is significantly reduced under the method of the present invention. The peak output power is reduced from 1.282MW without energy storage control strategy and 1.054MW with droop control strategy to 0.799MW. The standard deviation of output power is reduced from 0.5008MW without energy storage and 0.3963MW with droop control to 0.3318MW.

[0182] Depend on Figure 12 It can be seen that, compared with other strategies, the method of the present invention increases the output power during flywheel energy storage frequency regulation, and the flywheel output range is more flexible.

[0183] In summary, this method demonstrates a more significant effect in suppressing system frequency deviation and restoring frequency. Under this method, the flywheel energy storage undertakes more frequency regulation needs, resulting in a significant reduction in the output fluctuation of thermal power units. Simultaneously, the range of power output variation of thermal power units is narrowed, fully utilizing the advantages of high flywheel power and fast response. This effectively alleviates the frequency regulation pressure on thermal power units, contributing to their safe and stable operation.

[0184] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A control system for the coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation, wherein the thermal power units and flywheel energy storage are connected to the grid, characterized in that, It includes a signal decomposition module, a thermal power unit actual power acquisition module, a flywheel energy storage actual power acquisition module, and a frequency modulation power output module; The signal decomposition module is used to decompose the low-frequency power component and high-frequency power component of the primary frequency regulation command determined by the grid frequency deviation based on the tracking differentiator. The actual power acquisition module of the thermal power unit is used to use the low-frequency power component as the reference power of the thermal power unit and obtain the actual power of the thermal power unit through the thermal power unit coordination and control system. The flywheel energy storage actual power acquisition module is used to adaptively adjust the gain of the high-frequency power component based on the real-time changes in the flywheel energy storage state of charge and the grid frequency deviation to obtain the flywheel allocated power. Then, based on the flywheel allocated power, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical expected power of the flywheel energy storage. Next, the theoretical expected power of the flywheel energy storage is constrained by a Logistic regression function based on the flywheel energy storage state of charge and to prevent overcharging and over-discharging of the flywheel energy storage to obtain the reference power of the flywheel energy storage. Finally, the actual power of the flywheel energy storage is obtained through the flywheel energy storage control system, and the state of charge is monitored in real time based on the actual power of the flywheel energy storage to determine the state of charge of the flywheel energy storage. The frequency regulation power output module is used to take the sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage as the frequency regulation power for the thermal power unit and the flywheel energy storage to participate in grid frequency regulation in a coordinated manner. The specific method for obtaining the flywheel power distribution by adapting the gain of the high-frequency power component to the real-time changes in flywheel energy storage state of charge and grid frequency deviation includes: Based on the real-time state of charge of the flywheel energy storage, the state of charge gain coefficient of the flywheel energy storage during charging and discharging is obtained. In the formula, K c and K d These are the state-of-charge gain coefficients for flywheel energy storage during charging and discharging, respectively; K0 is the initial gain coefficient; S soc For real-time energy storage state of charge, S SOCmax S SOCmin These are the maximum and minimum values ​​of the state of charge, respectively. Based on real-time grid frequency deviation, the frequency deviation gain coefficient of flywheel energy storage is obtained. In the formula, α is the frequency deviation gain coefficient of flywheel energy storage; f d The right endpoint value of the frequency modulation dead zone; Δf m This represents the maximum system frequency deviation. Based on the state-of-charge gain coefficient and frequency deviation gain coefficient of the flywheel energy storage during charging and discharging, the gain coefficient of the adaptive flywheel energy storage state of charge and grid frequency deviation is obtained. In the formula, K D The gain coefficient for adaptive flywheel energy storage state of charge changes and grid frequency deviation changes; The flywheel power allocation is obtained by using the gain coefficients of the high-frequency power components and the real-time changes in the adaptive flywheel energy storage state of charge and grid frequency deviation. P fast =K D ×P D In the formula, P fast Distribute power to the flywheel; P D It represents the high-frequency power component.

2. A control method for the coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation, wherein the grid is connected to thermal power units and flywheel energy storage, characterized in that, include: Based on the tracking differentiator, the primary frequency regulation command determined by the grid frequency deviation is decomposed into low-frequency power components and high-frequency power components. The low-frequency power component is used as the reference power of the thermal power unit, and the actual power of the thermal power unit is obtained through the thermal power unit coordination and control system. The high-frequency power component is adaptively adjusted for changes in the flywheel energy storage state of charge and the real-time variation of the grid frequency deviation to obtain the flywheel allocated power. Based on the flywheel allocated power, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical expected power of the flywheel energy storage. The theoretical expected power of the flywheel energy storage is constrained by a Logistic regression function based on the flywheel energy storage state of charge and to prevent overcharging and over-discharging of the flywheel energy storage to obtain the reference power of the flywheel energy storage. The actual power of the flywheel energy storage is then obtained through the flywheel energy storage control system, and the state of charge of the flywheel energy storage is monitored in real time based on the actual power of the flywheel energy storage to determine the state of charge of the flywheel energy storage. The sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage is taken as the frequency regulation power for the thermal power unit and the flywheel energy storage to participate in grid frequency regulation in a coordinated manner. The specific method for obtaining the flywheel power distribution by adapting the gain of the high-frequency power component to the real-time changes in flywheel energy storage state of charge and grid frequency deviation includes: Based on the real-time state of charge of the flywheel energy storage, the state of charge gain coefficient of the flywheel energy storage during charging and discharging is obtained. In the formula, K c and K d These are the state-of-charge gain coefficients for flywheel energy storage during charging and discharging, respectively; K0 is the initial gain coefficient; S soc For real-time energy storage state of charge, S SOCmax S SOCmin These are the maximum and minimum values ​​of the state of charge, respectively. Based on real-time grid frequency deviation, the frequency deviation gain coefficient of flywheel energy storage is obtained. In the formula, α is the frequency deviation gain coefficient of flywheel energy storage; f d The right endpoint value of the frequency modulation dead zone; Δf m This represents the maximum system frequency deviation. Based on the state-of-charge gain coefficient and frequency deviation gain coefficient of the flywheel energy storage during charging and discharging, the gain coefficient of the adaptive flywheel energy storage state of charge and grid frequency deviation is obtained. In the formula, K D The gain coefficient for adaptive flywheel energy storage state of charge changes and grid frequency deviation changes; The flywheel power allocation is obtained by using the gain coefficients of the high-frequency power components and the real-time changes in the adaptive flywheel energy storage state of charge and grid frequency deviation. P fast =K D ×P D In the formula, P fast Distribute power to the flywheel; P D It represents the high-frequency power component.

3. The control method for coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation according to claim 2, characterized in that, The specific method for decomposing the low-frequency power component and high-frequency power component of the primary frequency regulation command determined by the grid frequency deviation includes: The primary frequency regulation command P is determined by the grid frequency deviation. G , P G =-K G ×Δf In the formula, K G Δf is the static characteristic coefficient of the power frequency of the thermal power unit; Δf is the system frequency deviation. The primary frequency modulation command P is applied using a tracking differentiator. G The power components are decomposed to obtain low-frequency and high-frequency power components. In the formula, P T (k+1) and P T (k) represent the low-frequency power components at sampling times k+1 and k, respectively; P D (k+1) and P D (k) represents the high-frequency power components at sampling times k+1 and k, respectively; h is the sampling period; and fhan is the fastest control synthesis function.

4. The control method for coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation according to claim 3, characterized in that, The specific method for using the low-frequency power component as the reference power of the thermal power unit and obtaining the actual power of the thermal power unit through the thermal power unit coordination and control system is as follows: P Gact =G en (s)*G ov (s)*P T In the formula, P Gact G represents the actual power output of the thermal power unit. en (s) is the transfer function of the steam turbine; G ov (s) is the transfer function of the speed governor; P T This represents the low-frequency power component.

5. The control method for coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation according to claim 4, characterized in that, Based on the flywheel's allocated power, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical expected power of the flywheel energy storage. The theoretical expected power of the flywheel energy storage is then constrained by a Logistic regression function based on the flywheel's state of charge to prevent overcharging and over-discharging, resulting in a reference power for the flywheel energy storage. Finally, the specific method for obtaining the actual power of the flywheel energy storage through the flywheel energy storage control system includes: Based on the grid frequency deviation, the flywheel energy storage droop control command is determined. P f =-K f ×Δf In the formula, P f For flywheel energy storage droop control commands; K f The power-frequency static characteristic coefficient of flywheel energy storage; Based on the flywheel power distribution, the droop control command is adaptively corrected to obtain the theoretical expected power of the flywheel's energy storage. P f =P fast +P f In the formula, P f ′ represents the theoretical power output of the flywheel energy storage; Based on the flywheel energy storage state of charge, the charging constraint power and discharging constraint power of the flywheel energy storage are obtained. In the formula, P c For charging-constrained power, P d For the discharge constraint power, P m Rated power of the energy storage system; S SOCmax The maximum permissible state of charge; S SOCmin The minimum allowable state of charge; K, P, P0, B, and R are the first, second, third, fourth, and fifth constants, respectively; Based on the charging constraint power and discharging constraint power of the flywheel energy storage, a reference power for the flywheel energy storage is obtained. This reference power includes the charging reference power P of the flywheel energy storage. fref,c and discharge reference power P fref,d , Finally, the actual power P of the flywheel energy storage system is obtained through equivalent analysis. fact , P fact =G F (s)P fref In the formula, G F (s) is the transfer function of the flywheel energy storage control system after equivalent analysis; P fref The reference power for flywheel energy storage is P when the flywheel is charging. fref =P fref,c When the flywheel discharges, P fref =P fref,d .

6. The control method for coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation according to claim 5, characterized in that, The specific method for determining the state of charge of the flywheel energy storage by real-time monitoring of its actual power includes: In the formula, S SOC State of charge of flywheel energy storage; S SOC0 The initial state of charge of the flywheel energy storage system is represented by E; the total energy storage capacity of the flywheel energy storage system is represented by E.

7. The control method for coordinated participation of thermal power units and flywheel energy storage in grid frequency regulation according to claim 6, characterized in that, The specific method for using the sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage as the frequency regulation power for the thermal power unit and the flywheel energy storage to participate in grid frequency regulation in a coordinated manner includes: P act =P fact +P Gact In the formula, P act Frequency regulation power for thermal power units and flywheel energy storage to work together in grid frequency regulation.

8. A power grid frequency regulation method, wherein a thermal power unit and a flywheel energy storage are connected to the power grid, characterized in that, include: If the obtained grid frequency deviation falls outside the preset frequency regulation dead zone, then the thermal power unit and flywheel energy storage are controlled by the control method described in any one of claims 2 to 7, so as to adjust the grid frequency with the frequency regulation power of the thermal power unit and flywheel energy storage participating in grid frequency regulation.

9. The power grid frequency regulation method according to claim 8, characterized in that, The frequency modulation dead zone is in, This is the left endpoint value of the FM dead zone. This is the right endpoint value of the FM dead zone.

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