Control system and method for thermal power generating unit and flywheel energy storage to collaboratively participate in power grid frequency modulation and power grid frequency modulation method

Abstract

The invention discloses a control system and method for a thermal power generating unit and flywheel energy storage to cooperatively participate in power grid frequency modulation and a power grid frequency modulation method. According to the method, a low-pass filtering algorithm is abandoned, a tracking differentiator is used for decomposing a primary frequency modulation instruction of the thermal power generating unit, and decomposed low-frequency power components are distributed to the thermal power generating unit; high-frequency power components are distributed to the flywheel for energy storage, action times and output abrasion of the thermal power generating unit are reduced, and the service life of the unit is prolonged. A gain coefficient which adaptively changes along with the state of charge (SOC) and frequency deviation is introduced into the decomposed high-frequency power component, so that accurate matching requirements are facilitated, the energy utilization efficiency is improved, the frequency fluctuation of a power grid is better stabilized, and the quality of the power grid is improved; and meanwhile, a Logistic function for preventing the flywheel from being overcharged and overdischarged is introduced to restrain the theoretical response power of flywheel energy storage, deep charging and discharging of the flywheel are avoided, and therefore the loss of the flywheel is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of flywheel energy storage, and in particular relates to a control system and method for a thermal power unit and a flywheel energy storage to collaboratively participate in power grid frequency regulation, and a power grid frequency regulation method. Background Art

[0002] As my country's traditional power system gradually transforms to a new power system, the proportion of renewable energy represented by photovoltaic and wind power has further increased, but the randomness and intermittency of renewable energy can easily cause instability in the grid frequency. Traditional thermal power units have shortcomings such as slow frequency regulation speed and low accuracy, so new frequency regulation methods need to be introduced to solve a series of problems caused by large-scale grid connection of renewable energy.

[0003] As a key technology of the energy revolution, energy storage can provide guarantee for the stable operation of the power system. Among the many energy storage methods, flywheel energy storage has significant advantages in frequency regulation due to its advantages such as fast response and many charging and discharging times. At present, some technicians have proposed the strategy of using flywheel energy storage to assist thermal power units in participating in frequency regulation. On the one hand, this strategy can reduce the output of thermal power units, and on the other hand, it can improve the quality of frequency regulation and ensure the safe and stable operation of the power grid. However, this common strategy of using flywheel energy storage to assist thermal power units in participating in frequency regulation generally uses a low-pass filter to decompose the high-frequency signal and low-frequency signal of a frequency regulation instruction. This method is difficult to take into account both the smoothing of thermal power unit output fluctuations and the charging and discharging safety of the flywheel energy storage system. For example, the existing technology named "Frequency Regulation Control Strategy of Flywheel Energy Storage Coupled Thermal Power Units under Multiple Operating Stages", such as Figure 1 As shown, the low-pass filtering link in the prior art adopts a first-order Butterworth low-pass filter, and the transfer function T1 is the low-pass filter time constant, and the decomposed low-frequency signal P tpu =-K G Δf G F (s), high frequency signal P disf =-K G ·Δf·(1-G F (s)). The low-pass filter algorithm used in the prior art has a fixed cutoff frequency and simple 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 the combined thermal storage system, faced with different power shortages during the frequency deterioration period and the recovery period, it is difficult to make adaptive adjustments according to specific application requirements to achieve the best filtering effect. Therefore, it is not possible to give full play to the timeliness of the "power-type" flywheel energy storage in responding to the load when the frequency regulation command changes rapidly, and the stability of the "energy-type" coal-fired power unit in responding to the load when the frequency regulation command changes slowly. At the same time, fixed parameters cannot keep the flywheel in a reasonable working range while ensuring the quality of grid frequency regulation.

[0004] In addition, the current conventional flywheel energy storage strategy mostly uses droop control to directly determine the flywheel power, which cannot fully utilize the advantages of flywheel energy storage such as fast response and high number of charge and discharge times. Moreover, this strategy has not been able to effectively alleviate the loss of unit life caused by frequent output and severe wear of thermal power units. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention proposes a control system and method for a thermal power unit and a flywheel energy storage to collaboratively participate in power grid frequency regulation, as well as a power grid frequency regulation method.

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

[0007] A control system for a thermal power unit and a flywheel energy storage to collaboratively participate in power grid frequency modulation, wherein the thermal power unit and the flywheel energy storage are connected to the power grid, and comprises 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;

[0008] The signal decomposition module is used to perform signal decomposition of low-frequency power components and high-frequency power components on the primary frequency modulation instruction determined by the power 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 acquire the actual power of the thermal power unit via the thermal power unit coordination control system;

[0010] The flywheel energy storage actual power acquisition module is used to perform adaptive flywheel energy storage charge state and grid frequency deviation real-time change gain on the high-frequency power component to obtain flywheel distribution power, and then adaptively correct the droop control instruction determined by the grid frequency deviation based on the flywheel distribution power to obtain the theoretical power that the flywheel energy storage should generate, and then constrain the theoretical power that the flywheel energy storage should generate based on the flywheel energy storage charge state and prevent the flywheel energy storage from being overcharged or over-discharged to obtain the reference power of the flywheel energy storage, and finally obtain the actual power of the flywheel energy storage through the flywheel energy storage control system, and perform real-time charge state monitoring based on the actual power of the flywheel energy storage to determine the charge state of the flywheel energy storage;

[0011] The frequency modulation power output module is used to use the sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage as the frequency modulation power for the thermal power unit and the flywheel energy storage to collaboratively participate in the frequency modulation of the power grid.

[0012] A control method for a thermal power unit and a flywheel energy storage to collaboratively participate in power grid frequency modulation, wherein the thermal power unit and the flywheel energy storage are connected to the power grid, comprising:

[0013] Based on the tracking differentiator, the signal of low-frequency power component and high-frequency power component of the primary frequency modulation instruction determined by the grid frequency deviation is decomposed;

[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 control system;

[0015] The high-frequency power component is adaptively adjusted to the gain of the real-time change of the flywheel energy storage charge state and the grid frequency deviation to obtain the flywheel distribution power; based on the flywheel distribution power, the droop control instruction determined by the grid frequency deviation is adaptively corrected to obtain the theoretical power that the flywheel energy storage should generate; the theoretical power that the flywheel energy storage should generate is constrained by a Logistic regression function based on the flywheel energy storage charge state and preventing the flywheel energy storage from being overcharged or over-discharged to obtain the reference power of the flywheel energy storage, and then the actual power of the flywheel energy storage is obtained through the flywheel energy storage control system, and the real-time charge state monitoring is performed based on the actual power of the flywheel energy storage to determine the charge state 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 of the thermal power unit and the flywheel energy storage in collaboratively participating in the frequency regulation of the power grid.

[0017] Furthermore, the specific method of performing signal decomposition of low-frequency power components and high-frequency power components on the primary frequency modulation instruction determined by the power 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 is the power-frequency static characteristic coefficient of the thermal power unit; Δf is the system frequency deviation;

[0021] The tracking differentiator is used to adjust the primary frequency modulation instruction P G Decompose to obtain low-frequency power components and high-frequency power components.

[0022]

[0023] Where P T (k+1) and P T (k) are the low-frequency power components at the k+1th and kth sampling moments respectively; P D (k+1) and P D (k) are the high-frequency power components at the k+1th and kth sampling moments respectively; h is the sampling period; fhan is the fastest control comprehensive function.

[0024] Furthermore, the specific method of 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 control system is as follows:

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

[0026] Where P Gact is the actual power of the thermal power unit; G en (s) is the transfer function of the steam turbine; G ov (s) is the transfer function of the speed regulator; P T is the low frequency power component.

[0027] Furthermore, the specific method of performing adaptive flywheel energy storage charge state and grid frequency deviation real-time gain on the high-frequency power component to obtain flywheel distribution power includes:

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

[0029]

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

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

[0032]

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

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

[0035]

[0036] In the formula, KD is the gain coefficient for adaptively adjusting the change of charge state of flywheel energy storage and the change of grid frequency deviation;

[0037] The flywheel distribution power is obtained by adjusting the high-frequency power component, the adaptive flywheel energy storage charge state and the gain coefficient of the grid frequency deviation in real time,

[0038] P fast =K D ×P D

[0039] Where P fast Distribute power to the flywheel; P D is the high frequency power component.

[0040] Further, based on the flywheel allocated power, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical power that the flywheel energy storage should generate, the theoretical power that the flywheel energy storage should generate is constrained by a Logistic regression function based on the charge state of the flywheel energy storage to prevent overcharging and over-discharging of the flywheel energy storage, and the reference power of the flywheel energy storage is obtained. Finally, the specific method for obtaining the actual power of the flywheel energy storage via 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] Where P f K is the flywheel energy storage droop control instruction; f is the flywheel energy storage power-frequency static characteristic coefficient;

[0044] Based on the flywheel power distribution, the droop control command is adaptively modified to obtain the theoretical power that the flywheel energy storage should generate.

[0045] P f ′=P fast +P f

[0046] Where P f ' is the theoretical power that the flywheel energy storage should generate;

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

[0048]

[0049] Where P c is the charging constraint power, P d is the discharge constraint power, P mis the rated power of the energy storage system; S SOCmax is the maximum allowed state of charge value; S SOCmin is the minimum allowed state of charge value; K, P, P0, B and R are the first, second, third, fourth and fifth constants respectively;

[0050] Based on the charge constraint power and discharge constraint power of the flywheel energy storage, the reference power of the flywheel energy storage is obtained, and the reference power of the flywheel energy storage includes the charge 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 is obtained through the flywheel energy storage control system after 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 is the reference power of flywheel energy storage, when the flywheel is charged, P fref =P fref,c , when the flywheel discharges P fref =P fref,d .

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

[0057]

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

[0059] Furthermore, the specific method of 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 collaboratively participate in the frequency regulation of the power grid includes:

[0060] P act =P fact +P Gact

[0061] Where P actIt is the frequency regulation power for thermal power units and flywheel energy storage to collaboratively participate in grid frequency regulation.

[0062] A method for frequency modulation of a power grid, wherein a thermal power generation unit and a flywheel energy storage are connected to the power grid, comprising:

[0063] Determine whether the acquired grid frequency deviation falls outside a preset frequency regulation dead zone. If so, the thermal power unit and the flywheel energy storage are controlled by the control method for the thermal power unit and the flywheel energy storage to collaboratively participate in grid frequency regulation as described in any of the above items, and the grid frequency is adjusted by the frequency regulation power of the thermal power unit and the flywheel energy storage to collaboratively participate in grid frequency regulation.

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

[0065] An electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor is used to call and run the computer program stored in the memory to execute any of the methods described above.

[0066] A computer-readable storage medium stores a computer program, wherein the computer program implements the steps of any of the above methods when executed by a processor.

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

[0068] The present invention proposes a control system and method for a thermal power unit and a flywheel energy storage to collaboratively participate in the frequency modulation of a power grid. The method abandons the low-pass filtering algorithm and uses a tracking differentiator to decompose the frequency modulation instruction of the thermal power unit. The decomposed low-frequency power component (signal) is allocated to the thermal power unit, and the high-frequency power component (signal) is allocated to the flywheel energy storage. The flywheel's characteristics of rapid response and multiple charge and discharge times are fully utilized, reducing the number of thermal power unit actions and output wear, and extending the life of the unit. A gain coefficient that changes adaptively with the state of charge SOC and frequency deviation is introduced into the decomposed high-frequency power component, so that the high-frequency power classification can be adaptively adjusted according to the change of the state of charge SOC and the frequency modulation amplitude, which is conducive to accurately matching the demand, improving the energy utilization efficiency, better smoothing the frequency fluctuation of the power grid, and improving the quality of the power grid; at the same time, a Logistics function that prevents the flywheel from overcharging and over-discharging is introduced to constrain the theoretical power output of the flywheel energy storage, avoid deep charge and discharge of the flywheel, thereby reducing the loss of the flywheel and extending its service life.

[0069] The present invention proposes a power grid frequency regulation method, which, through the coordination between flywheel and thermal power unit, decomposes the primary frequency regulation instruction into low-frequency power component and high-frequency power component, respectively distributes them to thermal power unit and flywheel energy storage unit, and establishes a coordinated dispatch mechanism of thermal energy storage combined system. This strategy can give full play to the functional characteristics of flywheel "power type" and thermal power "energy type", and at the same time can improve the power quality and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a system block diagram of using a low-pass filter to decompose a frequency modulation instruction signal in the background technology;

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

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

[0073] Figure 4 It is a schematic diagram of signal decomposition of a tracking differentiator in an embodiment;

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

[0075] Figure 6 It is a flow chart of a control method for the thermal power generation unit and the flywheel energy storage to collaboratively participate in the frequency regulation of the power grid in the embodiment;

[0076] Figure 7 Schematic diagram of frequency deviation variation curves of different control strategies under step disturbance in application example 1;

[0077] Figure 8 It is a schematic diagram of the output power curve of the thermal power unit under different control strategies under the step disturbance in the first embodiment;

[0078] Fig. 9 It is a schematic diagram of the flywheel energy storage output power curve of different control strategies under step disturbance in the first embodiment;

[0079] Fig.10 A schematic diagram of a frequency deviation variation curve of different control strategies under continuous disturbance in the second embodiment;

[0080] Fig.11 It is a schematic diagram of the output power curve of the thermal power unit under different control strategies under continuous disturbance in the second embodiment;

[0081] Fig.12 Schematic diagram of flywheel energy storage output power curves using different control strategies under continuous disturbance in the second embodiment. DETAILED DESCRIPTION

[0082] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0083] Embodiment 1:

[0084] The present invention provides a control system for a thermal power generation unit and a flywheel energy storage unit to coordinately participate in the frequency modulation of a power grid. The power grid is connected with a thermal power generation unit and a flywheel energy storage unit, such as Figure 2 to Figure 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 charge state monitoring module;

[0085] A signal decomposition module, used for performing signal decomposition of low-frequency power components and high-frequency power components of a primary frequency modulation instruction determined by a power grid frequency deviation based on a tracking differentiator;

[0086] 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 control system;

[0087] The actual power acquisition module of the flywheel energy storage is used to adaptively adjust the high-frequency power component to the gain of the real-time change of the flywheel energy storage charge state and the grid frequency deviation, obtain the flywheel distribution power, and then adaptively correct the droop control command determined by the grid frequency deviation based on the flywheel distribution power to obtain the theoretical power that the flywheel energy storage should generate, and then constrain the theoretical power that the flywheel energy storage should generate based on the flywheel energy storage charge state and prevent the flywheel energy storage from being overcharged or over-discharged, and obtain the reference power of the flywheel energy storage, and finally obtain the actual power of the flywheel energy storage through the flywheel energy storage control system, and perform real-time charge state monitoring based on the actual power of the flywheel energy storage to determine the charge state of the flywheel energy storage;

[0088] The frequency regulation power output module is used to use 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 collaboratively participate in the frequency regulation of the power grid.

[0089] Embodiment 2:

[0090] The present invention provides a control method for a thermal power unit and a flywheel energy storage unit to coordinately participate in power grid frequency modulation. A thermal power unit and a flywheel energy storage unit are connected to a power grid. Figure 4 and Figure 6 As shown, the specific steps are as follows:

[0091] S1. Based on the tracking differentiator, the primary frequency modulation instruction determined by the grid frequency deviation is subjected to signal decomposition of low-frequency power component and high-frequency power component;

[0092] S2, 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 control system;

[0093] S3, adaptively adjust the high-frequency power component to the gain of the real-time change of the flywheel energy storage charge state and the 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 power that the flywheel energy storage should generate; constrain the theoretical power that the flywheel energy storage should generate based on the flywheel energy storage charge state and prevent the flywheel energy storage from being overcharged or over-discharged, obtain the reference power of the flywheel energy storage, and then obtain the actual power of the flywheel energy storage through the flywheel energy storage control system, and perform real-time charge state monitoring based on the actual power of the flywheel energy storage to determine the charge state of the flywheel energy storage;

[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 collaboratively participate in the frequency regulation of the power grid.

[0095] Embodiment three:

[0096] This embodiment is further designed on the basis of the second embodiment in that: Figure 3 As shown, in this example, the specific method for performing signal decomposition of low-frequency power component and high-frequency power component on the primary frequency modulation instruction determined by the grid frequency deviation 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 is the power-frequency static characteristic coefficient of the thermal power unit; Δf is the system frequency deviation;

[0100] The tracking differentiator is used to adjust the frequency modulation instruction P G Decompose to obtain low-frequency power components and high-frequency power components.

[0101]

[0102] Where P T (k+1) and P T (k) are the low-frequency power components at the k+1th and kth sampling moments respectively; P D (k+1) and P D(k) are the high-frequency power components at the k+1th and kth sampling moments respectively; h is the sampling period; fhan is the fastest control comprehensive function, and the expression of the fastest control comprehensive function fhan is as follows:

[0103]

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

[0105] Embodiment 4:

[0106] This embodiment is further designed on the basis of the third embodiment in that: Figure 4 As shown, in this example, the low-frequency power component is used as the reference power of the thermal power unit, and the specific method of obtaining the actual power of the thermal power unit through the thermal power unit coordinated control system is as follows:

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

[0108] Where P Gact is the actual power of the thermal power unit; G en (s) is the transfer function of the steam turbine; G ov (s) is the transfer function of the speed regulator; P T is the low frequency power component.

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

[0110]

[0111] In the formula, F HP 、F IP 、F LP are the power coefficients of the high, medium and low pressure cylinders of the steam turbine respectively; T CH 、T RH 、T CO are the volume time constants of high pressure steam, reheat steam and low pressure steam respectively;

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

[0113]

[0114] Where, T g is the time constant of the speed regulator.

[0115] Embodiment five:

[0116] This embodiment is further designed on the basis of the fourth embodiment in that: Figure 4 As shown, in this example, the specific method of performing adaptive flywheel energy storage charge state and grid frequency deviation real-time gain on the high-frequency power component to obtain flywheel distribution power includes:

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

[0118]

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

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

[0121]

[0122] Where, α is the frequency deviation gain coefficient of flywheel energy storage; f d is the right endpoint of the FM dead zone, generally 0.033Hz; Δf m is the maximum value of system frequency deviation;

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

[0124]

[0125] In the formula, K D is the gain coefficient for adaptively adjusting the change of charge state of flywheel energy storage and the change of grid frequency deviation;

[0126] The flywheel distribution power is obtained by taking into account the high-frequency power component, the adaptive flywheel energy storage charge state and the gain coefficient of the real-time change of the grid frequency deviation.

[0127] P fast =K D ×P D

[0128] Where P fast Distribute power to the flywheel; P D is the high frequency power component.

[0129] Embodiment six:

[0130] This embodiment is further designed on the basis of the fifth embodiment in that: Figure 4 and Figure 5 As shown, in this example, based on the flywheel power distribution, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical power of the flywheel energy storage, and the theoretical power of the flywheel energy storage is constrained by a Logistic regression function based on the charge state of the flywheel energy storage to prevent overcharging and over-discharging of the flywheel energy storage, so as to obtain the reference power of the flywheel energy storage. Finally, the specific method of 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] Where P f K is the flywheel energy storage droop control instruction; f is the flywheel energy storage power-frequency static characteristic coefficient;

[0134] Based on the flywheel power distribution, the droop control command is adaptively corrected to obtain the theoretical power that the flywheel energy storage should generate.

[0135] P f ′=P fast +P f

[0136] Where P f ' is the theoretical power that the flywheel energy storage should generate;

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

[0138]

[0139] Where P c is the charging constraint power, P d is the discharge constraint power, P m is the rated power of the energy storage system; S SOCmax is the maximum allowed state of charge value; S SOCmin is the minimum allowed state of charge value; K, P, P0, B and R are the first, second, third, fourth and fifth constants respectively;

[0140] Based on the charge constraint power and discharge constraint power of the flywheel energy storage, the reference power of the flywheel energy storage is obtained. The reference power of the flywheel energy storage includes the charge 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 is obtained through the flywheel energy storage control system after 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 is the reference power of flywheel energy storage, when the flywheel is charged, P fref =P fref,c , when the flywheel discharges P fref =P fref,d .

[0145] Embodiment seven:

[0146] This embodiment is further designed on the basis of the sixth embodiment in that in this embodiment, 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 S is the charge state of the flywheel energy storage; SOC0 is the initial charge state of the flywheel energy storage system; E is the total storage capacity of the flywheel energy storage.

[0149] Embodiment eight:

[0150] This embodiment is further designed on the basis of the seventh embodiment in that in this embodiment, the specific method of 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 of the thermal power unit and the flywheel energy storage to participate in the grid frequency regulation in a coordinated manner includes:

[0151] P act =P fact +P Gact

[0152] Where P act It is the frequency regulation power for thermal power units and flywheel energy storage to collaboratively participate in grid frequency regulation.

[0153] Embodiment nine:

[0154] A power grid frequency modulation method of the present invention, a thermal power generation unit and a flywheel energy storage are connected to the power grid, such as Figure 2As shown, including:

[0155] It is determined whether the obtained grid frequency deviation falls outside the preset frequency regulation dead zone. If so, the thermal power generation unit and the flywheel energy storage are controlled by the control method of the present invention for the coordinated participation of the thermal power generation unit and the flywheel energy storage in the grid frequency regulation, and the grid frequency is adjusted by the frequency regulation power of the thermal power generation unit and the flywheel energy storage in the coordinated participation of the grid frequency regulation. If not, the thermal power generation unit and the flywheel energy storage do not participate in the frequency regulation. The above-mentioned preset frequency regulation dead zone can be is the left endpoint value of the FM dead zone, is the right endpoint value of the FM dead zone. Generally,

[0156] Embodiment ten:

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

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

[0159] Application Example 1:

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

[0161] Table 1 Simulation parameters of thermal power units

[0162] parameter Numeric <![CDATA[Governor time constant T g / s]]> 0.08 <![CDATA[The droop coefficient K of the 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 inertia constant H 5 Generator load damping factor D 1

[0163] Table 2 Flywheel simulation parameters

[0164] parameter Numeric <![CDATA[Stator resistance R s / Ω]]> 0.001506 Permanent magnet flux 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 max |, Steady-state frequency deviation absolute value |Δf s |, and from |Δf max | to |Δf s |The time Δt elapsed s 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 by simulation under different step disturbance strategies are shown in Figure 7 to Figure 9 The calculation of various indicators is shown in Table 3:

[0167] Table 3 Frequency evaluation index 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 Droop control 0.03624 0.03024 18.236 Strategy of the present invention 0.03285 0.03005 16.025

[0169] It can be seen from Table 3 that under step disturbance, the maximum frequency deviation absolute value |Δf max |It is reduced by 34.39% compared with the control strategy without energy storage and by 9.35% compared with the droop control strategy. The absolute value of the steady-state frequency deviation of the method of the present invention |Δf s |It is 24.50% less than the control strategy without energy storage and 0.628% less than the droop control strategy. Figure 7 It can be seen that under the method of the present invention, the transient deviation and steady-state deviation of the system frequency are significantly reduced, the system frequency fluctuation is 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 is reduced from 2.688MW without energy storage control strategy to 1.928MW. Although the steady-state value of the method of the present 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 the present invention reduces the requirements of the thermal power unit on the unit output power during the primary frequency regulation period, and has a more obvious effect on reducing the primary frequency regulation pressure of thermal power.

[0171] Depend on Fig. 9 It can be seen that when the frequency just changes, the flywheel responds quickly under the method of the present invention, the output power reaches a peak value in a short time, and the stored electricity is released.

[0172] Application Example 2:

[0173] The first application example illustrates that under step disturbance conditions, the method of the present invention can improve the overall frequency regulation effect. However, the frequency fluctuation that causes the unit to perform a frequency regulation is generally caused by continuous and irregular small-amplitude rapid load fluctuations. Therefore, this example simulates and analyzes the method of the present invention and the corresponding comparison strategy under continuous disturbance.

[0174] In this example, the system adds continuous small disturbances with amplitudes between [3,3]MW, and the simulation time is set to 80s. p-v , standard deviation of frequency deviation f SD As evaluation indicators, the smaller the corresponding values ​​of various indicators, the better the frequency modulation effect.

[0175]

[0176] Where Δf i is the grid frequency deviation at the i-th moment; is the average value of the grid frequency deviation frequency under continuous disturbance; N is the total number of adopted points.

[0177] The frequency deviation curve, thermal power unit output power curve and flywheel output power curve obtained under different strategies of continuous load disturbance obtained by simulation are shown in Figure 10-12 , and its index calculation is shown in Table 4:

[0178] Table 4 Frequency evaluation index under continuous disturbance

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

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

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

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

[0183] In summary, the method has a more obvious effect on suppressing the frequency difference of the system and restoring the frequency. Under the method of the present invention, the flywheel energy storage takes on more frequency regulation needs, the output fluctuation of the thermal power unit is significantly reduced, and the range of variation of the output power of the thermal power unit is reduced, making full use of the advantages of high power and fast response of the flywheel, effectively sharing the frequency regulation pressure of the thermal power unit, and facilitating the safe and stable operation of the thermal power unit.

[0184] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A control system for a thermal power unit and a flywheel energy storage to collaboratively participate in power grid frequency modulation, wherein the thermal power unit and the flywheel energy storage are connected to the power 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 perform signal decomposition of low-frequency power components and high-frequency power components on the primary frequency modulation instruction determined by the power 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 acquire the actual power of the thermal power unit via the thermal power unit coordination control system; The flywheel energy storage actual power acquisition module is used to perform adaptive flywheel energy storage charge state and grid frequency deviation real-time change gain on the high-frequency power component to obtain flywheel distribution power, and then adaptively correct the droop control instruction determined by the grid frequency deviation based on the flywheel distribution power to obtain the theoretical power that the flywheel energy storage should generate, and then constrain the theoretical power that the flywheel energy storage should generate based on the flywheel energy storage charge state and prevent the flywheel energy storage from being overcharged or over-discharged to obtain the reference power of the flywheel energy storage, and finally obtain the actual power of the flywheel energy storage through the flywheel energy storage control system, and perform real-time charge state monitoring based on the actual power of the flywheel energy storage to determine the charge state of the flywheel energy storage; The frequency modulation power output module is used to use the sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage as the frequency modulation power for the thermal power unit and the flywheel energy storage to collaboratively participate in the frequency modulation of the power grid.

2. A control method for a thermal power unit and a flywheel energy storage to collaboratively participate in power grid frequency modulation, wherein the thermal power unit and the flywheel energy storage are connected to the power grid, characterized in that: include: Based on the tracking differentiator, the signal of low-frequency power component and high-frequency power component of the primary frequency modulation instruction determined by the grid frequency deviation is decomposed; 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 control system; The high-frequency power component is adaptively adjusted to the gain of the real-time change of the flywheel energy storage charge state and the grid frequency deviation to obtain the flywheel distribution power; based on the flywheel distribution power, the droop control instruction determined by the grid frequency deviation is adaptively corrected to obtain the theoretical power that the flywheel energy storage should generate; the theoretical power that the flywheel energy storage should generate is constrained by a Logistic regression function based on the flywheel energy storage charge state and preventing the flywheel energy storage from being overcharged or over-discharged to obtain the reference power of the flywheel energy storage, and then the actual power of the flywheel energy storage is obtained through the flywheel energy storage control system, and the real-time charge state monitoring is performed based on the actual power of the flywheel energy storage to determine the charge state 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 used as the frequency regulation power of the thermal power unit and the flywheel energy storage in collaboratively participating in the frequency regulation of the power grid.

3. The control method for the coordinated participation of thermal power generation units and flywheel energy storage in power grid frequency modulation according to claim 2 is characterized in that: The specific method for performing signal decomposition of low-frequency power component and high-frequency power component on the primary frequency modulation instruction determined by the power grid frequency deviation comprises: The primary frequency regulation command P is determined by the grid frequency deviation G , P G =-K G ×Δf In the formula, K G is the power-frequency static characteristic coefficient of the thermal power unit; Δf is the system frequency deviation; The tracking differentiator is used to adjust the primary frequency modulation instruction P G Decompose to obtain low-frequency power components and high-frequency power components. Where P T (k+1) and P T (k) are the low-frequency power components at the k+1th and kth sampling moments respectively; P D (k+1) and P D (k) are the high-frequency power components at the k+1th and kth sampling moments respectively; h is the sampling period; fhan is the fastest control comprehensive function.

4. The control method for the thermal power generation unit and flywheel energy storage to collaboratively participate in the grid frequency modulation according to claim 3 is characterized in that: The specific method of 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 control system is as follows: P Gact =G en (s)*G ov (s)*P T Where P Gact is the actual power of the thermal power unit; G en (s) is the transfer function of the steam turbine; G ov (s) is the transfer function of the speed regulator; P T is the low frequency power component.

5. The control method for the coordinated participation of thermal power generation units and flywheel energy storage in power grid frequency modulation according to claim 4 is characterized in that: The specific method of performing adaptive flywheel energy storage charge state and grid frequency deviation real-time gain on the high-frequency power component to obtain flywheel distribution power includes: Based on the real-time charge state of the flywheel energy storage, the charge state gain coefficient of the flywheel energy storage during charging and discharging is obtained. In the formula, K c and K d are the state of charge gain coefficients of the flywheel energy storage during charging and discharging, respectively; K0 is the initial gain coefficient; S soc is the real-time energy storage charge state, S SOCmax , S SOCmin are the maximum and minimum values ​​of the state of charge respectively; Based on the real-time grid frequency deviation, the frequency deviation gain coefficient of the flywheel energy storage is obtained. Where, α is the frequency deviation gain coefficient of flywheel energy storage; f d is the right endpoint value of the frequency modulation dead zone; Δf m is the maximum value of system frequency deviation; Based on the charge state gain coefficient of the flywheel energy storage during charging and discharging and the frequency deviation gain coefficient of the flywheel energy storage, a gain coefficient of the adaptive flywheel energy storage charge state and the real-time change of the grid frequency deviation is obtained, In the formula, K D is the gain coefficient for adaptively adjusting the change of charge state of flywheel energy storage and the change of grid frequency deviation; The flywheel distribution power is obtained by adjusting the high-frequency power component, the adaptive flywheel energy storage charge state and the gain coefficient of the grid frequency deviation in real time, P fast =K D ×P D Where P fast Distribute power to the flywheel; P D is the high frequency power component.

6. The control method for the thermal power generation unit and flywheel energy storage to collaboratively participate in the grid frequency modulation according to claim 5, characterized in that: Based on the flywheel allocated power, the droop control command determined by the grid frequency deviation is adaptively corrected to obtain the theoretical power that the flywheel energy storage should generate, the theoretical power that the flywheel energy storage should generate is constrained by a Logistic regression function based on the flywheel energy storage charge state to prevent overcharging and over-discharging of the flywheel energy storage, and the reference power of the flywheel energy storage is obtained. Finally, the specific method of 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 Where P f K is the flywheel energy storage droop control instruction; f is the flywheel energy storage power-frequency static characteristic coefficient; Based on the flywheel power distribution, the droop control command is adaptively modified to obtain the theoretical power that the flywheel energy storage should generate. P f ′=P fast +P f Where P f ' is the theoretical power that the flywheel energy storage should generate; Based on the charge state of the flywheel energy storage, the charging constraint power and the discharging constraint power of the flywheel energy storage are obtained, Where P c is the charging constraint power, P d is the discharge constraint power, P m is the rated power of the energy storage system; S SOCmax is the maximum allowed state of charge value; S SOCmin is the minimum allowed state of charge value; K, P, P0, B and R are the first, second, third, fourth and fifth constants respectively; Based on the charge constraint power and discharge constraint power of the flywheel energy storage, the reference power of the flywheel energy storage is obtained, and the reference power of the flywheel energy storage includes the charge 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 is obtained through the flywheel energy storage control system after 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 is the reference power of flywheel energy storage, when the flywheel is charged, P fref =P fref,c , when the flywheel discharges P fref =P fref,d .

7. The control method for the thermal power generation unit and flywheel energy storage to collaboratively participate in the grid frequency modulation according to claim 6, characterized in that: The specific method of performing real-time state of charge monitoring based on the actual power of the flywheel energy storage and determining the state of charge of the flywheel energy storage includes: In the formula, S SOC S is the charge state of the flywheel energy storage; SOC0 is the initial charge state of the flywheel energy storage system; E is the total storage capacity of the flywheel energy storage.

8. The control method for the thermal power generation unit and flywheel energy storage to collaboratively participate in the grid frequency modulation according to claim 7, characterized in that: The specific method of using the sum of the actual power of the thermal power unit and the actual power of the flywheel energy storage as the frequency modulation power for the thermal power unit and the flywheel energy storage to collaboratively participate in the frequency modulation of the power grid includes: P act =P fact +P Gact Where P act It is the frequency regulation power for thermal power units and flywheel energy storage to collaboratively participate in grid frequency regulation.

9. A method for frequency modulation of a power grid, wherein a thermal power unit and a flywheel energy storage are connected to the power grid, characterized in that: include: Determine whether the acquired grid frequency deviation falls outside a preset frequency regulation dead zone. If so, the thermal power unit and the flywheel energy storage are controlled by the control method for the thermal power unit and the flywheel energy storage to collaboratively participate in grid frequency regulation as described in any one of claims 2 to 8, and the grid frequency is adjusted by the frequency regulation power of the thermal power unit and the flywheel energy storage to collaboratively participate in grid frequency regulation.

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

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