Flywheel energy storage auxiliary frequency modulation control method for thermal power unit

Abstract

The application relates to the technical field of power systems, and discloses a flywheel energy storage auxiliary thermal power unit cooperative frequency modulation control method, which comprises the following steps: through a joint dynamic model, dominant dynamic characteristics are extracted based on state matrix eigenvalue analysis, and a hierarchical optimization time granularity is set accordingly; aiming at the difference between the slow dynamic characteristics of thermal power and the fast dynamic characteristics of a flywheel, optimization objective functions of the thermal power layer and the flywheel layer are respectively designed, robust consistency constraints are introduced, and multi-time scale optimization instruction iteration generation is realized through an asynchronous coordination algorithm. The system realizes real-time monitoring of the power grid frequency change rate, dynamically adjusts the flywheel virtual inertia parameter, generates a dynamic compensation power, finally fuses the coordinated reference instruction and the dynamic compensation amount to form an execution instruction. The scheme can realize significant improvement of the frequency dynamic stability in the new energy power grid frequency modulation process, and balance the frequency modulation equipment loss and the sustainable operation capacity of the energy storage system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power systems, and particularly relates to a flywheel energy storage assisted coordinated frequency regulation control method for thermal power generating units. BACKGROUND

[0002] With the gradual increase of new energy penetration, the stability of the power grid frequency is deteriorating, and it is urgent to improve the dynamic response capability and inertia support through the coordinated frequency regulation of thermal power and energy storage to avoid the risk of large-scale power outage caused by frequency collapse.

[0003] Traditional coordinated schemes mostly use fixed proportion allocation or simple superposition control, and do not fully consider the dynamic differences between thermal power and energy storage in the time scale, resulting in conflicts between the power instructions of slow dynamic units and fast dynamic energy storage in the cross-time dimension, which not only reduces the frequency regulation accuracy, but also aggravates the control oscillation risk. In addition, the existing methods lack adaptability to the dynamic changes of system inertia, and when the equivalent inertia decreases due to the increase of new energy penetration, they cannot adjust the virtual inertia support strength in real time, so that the frequency change rate suppression effect is limited and the system anti-disturbance ability is insufficient. The energy storage state of charge management strategy is also not deeply coupled with the frequency regulation demand, and excessive charging and discharging accelerates the equipment aging, while restricting the sustainable adjustment capability of the energy storage system.

[0004] Therefore, it is urgent to develop a flywheel energy storage assisted coordinated frequency regulation control method for thermal power generating units, which can significantly improve the frequency dynamic stability in the process of new energy power grid frequency regulation, while balancing the frequency regulation equipment loss and the sustainable operation capability of the energy storage system. SUMMARY

[0005] In order to solve the above technical problems, the application provides a flywheel energy storage assisted coordinated frequency regulation control method for thermal power generating units, which can significantly improve the frequency dynamic stability in the process of new energy power grid frequency regulation, while balancing the frequency regulation equipment loss and the sustainable operation capability of the energy storage system.

[0006] The application provides a flywheel energy storage assisted coordinated frequency regulation control method for thermal power generating units, which comprises the following steps:

[0007] S1, a joint dynamic model of the thermal power generating unit and the flywheel energy storage is constructed, and the joint dynamic model comprises a thermal power generating unit state equation and a flywheel energy storage state equation;

[0008] S2, based on the eigenvalues of the state matrix of the joint dynamic model, the dominant dynamic characteristics of the thermal power generating unit and the dominant dynamic characteristics of the flywheel energy storage are extracted;

[0009] S3, according to the time constant of the dominant dynamic characteristics of the thermal power generating unit, the first cycle time granularity of the thermal power layer optimization is set, and according to the time constant of the dominant dynamic characteristics of the flywheel energy storage, the second cycle time granularity of the flywheel layer optimization is set;

[0010] S4, constructing an optimization objective function of the thermal power layer according to the first periodic time granularity and constructing an optimization objective function of the flywheel layer according to the second periodic time granularity;

[0011] S5, defining a robust consistency constraint of the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer, iteratively optimizing the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer through an asynchronous coordination algorithm, and outputting the coordinated thermal power reference instruction and the flywheel reference instruction;

[0012] S6, monitoring a frequency change rate of the power system in real time, dynamically adjusting a virtual inertia parameter of the flywheel energy storage according to the frequency change rate, and generating a flywheel dynamic compensation power matched with the virtual inertia parameter;

[0013] S7, obtaining a thermal power unit execution instruction according to the coordinated thermal power reference instruction and a thermal power unit control input, and obtaining a flywheel energy storage execution instruction according to the coordinated flywheel reference instruction and the flywheel dynamic compensation power.

[0014] Further, in S1, the expression of the thermal power unit state equation is as follows:

[0015] ;

[0016] wherein, represents a change rate of the thermal power unit output power with time, T th represents a thermal power unit time constant, x1(t) represents a thermal power unit output power at time t, K th represents a thermal power unit gain coefficient, u th (t) represents a thermal power unit control input at time t, d1(t) represents a first renewable energy disturbance term at time t, and t represents time;

[0017] The expression of the flywheel energy storage state equation is as follows:

[0018] ;

[0019] wherein, represents a change rate of the flywheel energy storage output power with time, T f represents a flywheel energy storage time constant, x2(t) represents a flywheel energy storage output power at time t, K f represents a flywheel energy storage gain coefficient, u f (t) represents a flywheel energy storage control input at time t, and d2(t) represents a second renewable energy disturbance term at time t.

[0020] Further, in S3, the first periodic time granularity is a preset multiple of the thermal power unit time constant, and the second periodic time granularity is a preset multiple of the flywheel energy storage time constant.

[0021] Further, in S4, the expression of the optimization objective function of the thermal power layer is as follows:

[0022] ;

[0023] wherein n represents the nth first time window, the first time window length is a first periodic time granularity, u th (n) represents the optimization instruction of the thermal power layer in the nth first time window, u th (n-1) represents the optimization instruction of the thermal power layer in the (n-1)th first time window, N represents the total number of first time windows, a represents the quadratic term coefficient of the power generation cost of the thermal power unit, b represents the ramping penalty coefficient of the thermal power, p represents the coordination weight coefficient, and z(n) represents the coordination variable generated by the flywheel layer in the nth first time window.

[0024] Further, in S4, the expression of the optimization objective function of the flywheel layer is as follows:

[0025] ;

[0026] wherein m represents the mth second time window, the second time window length is a second periodic time granularity, u f (m) represents the optimization instruction of the flywheel layer in the mth second time window, M represents the total number of second time windows, b represents the flywheel energy storage loss coefficient, m represents the SOC penalty coefficient, SOC(m) represents the state of charge of the flywheel energy storage in the mth second time window, p represents the coordination weight coefficient, and z(m) represents the coordination variable generated by the thermal power layer in the mth second time window.

[0027] Further, in S5, the robust consistency constraint of the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer is defined as follows:

[0028] ;

[0029] wherein M represents the total number of second time windows, m represents the mth second time window, u f (m) represents the optimization instruction of the flywheel layer in the mth second time window, u th (n) represents the optimization instruction of the thermal power layer in the nth first time window, and max represents the maximum allowed power deviation.

[0030] Further, in S5, in the process of iterative optimization of the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer by the asynchronous coordination algorithm, the coordination variable is also updated, and the formula for updating the coordination variable is as follows:

[0031] ;

[0032] wherein, z represents a coordination variable generated by the flywheel layer or a coordination variable generated by the thermal power layer, z k+1 represents a coordination variable generated by the flywheel layer or a coordination variable generated by the thermal power layer in the k+1th iteration, k represents an iteration number, represents an optimization instruction of the thermal power layer in the k+1th iteration of the n th first time window, M represents a total number of second time windows, represents an optimization instruction of the flywheel layer in the kth iteration of the m th second time window.

[0033] Further, in S6, the dynamic adjustment rule of the virtual inertia parameter comprises:

[0034] When the power system frequency change rate is greater than a preset threshold, the virtual inertia parameter is adjusted to a preset multiple of a virtual inertia basic value; when the power system frequency change rate is less than or equal to the preset threshold, the virtual inertia parameter is adjusted to the virtual inertia basic value.

[0035] Further, in S6, the calculation formula of the flywheel dynamic compensation power is as follows:

[0036] ;

[0037] wherein, represents the flywheel dynamic compensation power at t time, represents a compensation gain, represents a frequency change rate.

[0038] Further, S7 specifically comprises: performing dead zone processing on the coordinated thermal power reference instruction and a thermal power unit control input to obtain a thermal power unit execution instruction;

[0039] Performing state of charge safety limiting processing on the flywheel reference instruction superimposed with the flywheel dynamic compensation power to obtain a flywheel energy storage execution instruction.

[0040] The embodiment of the present application has the following technical effects:

[0041] The scheme solves the control conflict problem caused by the mismatch of dynamic response by constructing a combined dynamic model of thermal power and flywheel energy storage, representing the slow and fast dynamic characteristics of the two based on state space separation, designing control objectives on the minute and second time scales respectively using a hierarchical optimization framework, and realizing consistent matching of cross-scale power instructions by combining an asynchronous coordination algorithm. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0043] Figure 1 is a flowchart of a flywheel energy storage assisted coordinated frequency modulation control method for a thermal power unit provided by an embodiment of the present application;

[0044] Figure 2 is a schematic diagram of iterative updating of a coordination variable provided by an embodiment of the present application;

[0045] Figure 3 is a comparison diagram of flywheel-thermal power coordination and independent frequency modulation effects provided by an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0047] An embodiment of the present application provides a flywheel energy storage assisted coordinated frequency modulation control method for a thermal power unit, Figure 1 is a flowchart of a flywheel energy storage assisted coordinated frequency modulation control method for a thermal power unit provided by an embodiment of the present application, referring to Figure 1 , the method comprises the following steps:

[0048] S1, a combined dynamic model of the thermal power generating unit and the flywheel energy storage is constructed, and the combined dynamic model comprises a state equation of the thermal power generating unit and a state equation of the flywheel energy storage.

[0049] In some embodiments, the expression of the state equation of the thermal power generating unit is as follows:

[0050] ;

[0051] wherein, represents a rate of change of the output power of the thermal power generating unit over time, T th represents a time constant of the thermal power generating unit, and an exemplary typical value is 30 s, x1(t) represents the output power of the thermal power generating unit at time t, K th represents a gain coefficient of the thermal power generating unit, u th (t) represents the control input of the thermal power generating unit at time t, d1(t) represents a first renewable energy disturbance item at time t, and t represents time;

[0052] The expression of the state equation of the flywheel energy storage is as follows:

[0053] ;

[0054] wherein, represents a rate of change of the output power of the flywheel energy storage over time, T f represents a time constant of the flywheel energy storage, and an exemplary typical value is 0.5 s, x2(t) represents the output power of the flywheel energy storage at time t, K f represents a gain coefficient of the flywheel energy storage, u f (t) represents the control input of the flywheel energy storage at time t, and d2(t) represents a second renewable energy disturbance item at time t.

[0055] S2, based on the eigenvalues of the state matrix of the combined dynamic model, the dominant dynamic characteristics of the thermal power generating unit and the dominant dynamic characteristics of the flywheel energy storage are extracted.

[0056] ;

[0057] wherein, A represents the state matrix, and the dominant dynamic characteristics λ th = of the thermal power generating unit and the dominant dynamic characteristics λ f = of the flywheel energy storage can be obtained according to the state matrix.

[0058] S3, according to the time constant of the dominant dynamic characteristics of the thermal power generating unit, a first period time granularity of the thermal power layer optimization is set, and according to the time constant of the dominant dynamic characteristics of the flywheel energy storage, a second period time granularity of the flywheel layer optimization is set.

[0059] In some embodiments, the first cycle time granularity is a preset multiple of a time constant of the thermal power unit, and the second cycle time granularity is a preset multiple of a time constant of the flywheel energy storage. For example, the first cycle time granularity can be set to 2T th , i.e. 60s, and the second cycle time granularity can be set to 2T f , i.e. 1s.

[0060] S4, constructing an optimization objective function of the thermal power layer according to the first cycle time granularity, and constructing an optimization objective function of the flywheel layer according to the second cycle time granularity.

[0061] In some embodiments, the expression of the optimization objective function of the thermal power layer is as follows:

[0062] ;

[0063] wherein n represents the nth first time window, the first time window length is the first cycle time granularity, u th (n) represents the optimization instruction of the thermal power layer in the nth first time window, u th (n-1) represents the optimization instruction of the thermal power layer in the (n-1)th first time window, N represents the total number of first time windows, a represents the quadratic term coefficient of the thermal power generation cost, which can be set to 0.005 for example, b represents the thermal power climbing penalty coefficient, which satisfies , which can be set to 0.1 for example, p represents the coordination weight coefficient, which can be set to 0.2 for example, and z(n) represents the coordination variable generated by the flywheel layer in the nth first time window. The thermal power unit has slow response speed, large capacity, and low cost, and the quadratic term and climbing penalty are introduced in the optimization objective to reduce the frequent adjustment of the thermal power, and to reduce wear and tear and fuel consumption.

[0064] In some embodiments, the expression of the optimization objective function of the flywheel layer is as follows:

[0065] ;

[0066] wherein m represents the mth second time window, the second time window length is the second cycle time granularity, u f (m) represents the optimization instruction of the flywheel layer in the mth second time window, M represents the total number of second time windows, M is the ratio of the first cycle time granularity to the second cycle time granularity, which is 60 when the first cycle time granularity is 60s and the second cycle time granularity is 1s for example, and b represents the flywheel energy storage loss coefficient, which satisfies , exemplary, can be set to 0.01, μ represents the SOC penalty coefficient, used to quantify the weight parameter of the deviation of the flywheel energy storage state of charge (SOC(m)) from the nominal value (0.5), exemplary, can be set to 100, SOC(m) represents the flywheel energy storage state of charge of the mth second time window, the safe range of SOC is [0.2, 0.8], and ρ represents the coordination weight coefficient, represents the coordination variable generated by the thermal power layer in the mth second time window. The flywheel responds quickly, but has small capacity and is sensitive to cycle life, and the SOC penalty term is used to limit the SOC in the safe range (0.2~0.8) to prolong the service life of the energy storage.

[0067] S5, defining the robust consistency constraint of the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer, iteratively optimizing the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer through an asynchronous coordination algorithm, and outputting the coordinated thermal power reference instruction and the flywheel reference instruction.

[0068] In some embodiments, the robust consistency constraint is as follows:

[0069] ;

[0070] wherein M represents the total number of second time windows, m represents the mth second time window, u f (m) represents the optimization instruction of the flywheel layer in the mth second time window, u th (n) represents the optimization instruction of the thermal power layer in the nth first time window, Δ max represents the maximum allowed power deviation, which can be set according to the actual situation, and in this embodiment, 3% of the rated power of the system is taken. The robust consistency constraint is used to force the thermal power and the flywheel output to be consistent on a long time scale, to prevent cumulative deviation caused by the difference in time scales (such as flywheel short-time over-compensation without follow-up of thermal power), and to avoid frequency secondary fluctuations caused by the uncoordinated output of thermal power and flywheel in the frequency modulation process by limiting the power deviation.

[0071] In some embodiments, in the process of iteratively optimizing the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer through the asynchronous coordination algorithm, the coordination variable is also updated, and the formula for updating the coordination variable is as follows:

[0072] ;

[0073] wherein z represents the coordination variable generated by the flywheel layer or the coordination variable generated by the thermal power layer, z k+1 represents the coordination variable generated by the flywheel layer or the coordination variable generated by the thermal power layer in the k+1th iteration, k represents the iteration number, represents the optimization instruction of the thermal power layer in the k+1th iteration of the nth first time window, and M represents the total number of the second time windows, represents the optimization instruction of the flywheel layer in the kth iteration of the mth second time window. The coordination variable z gradually approaches the global optimum through asynchronous fusion, and the economic efficiency of the thermal power and the dynamic performance of the flywheel are taken into account.

[0074] In some embodiments, the asynchronous coordination algorithm is an alternating direction multiplier method, the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer are iterated in layers by using the alternating direction multiplier method, and for example, the optimization objective function of the thermal power layer is executed once every 60s, the optimization objective function of the flywheel layer is executed once every 1s, and the coordination variable is updated at the same time in each iteration. Figure 2 is a schematic diagram of iterative updating of the coordination variable provided by an embodiment of the present application, referring to Figure 2 The ordinate represents the absolute value of the deviation of the control input of the thermal power unit or the control input of the flywheel energy storage from the coordination variable, and represents the deviation degree of the control instruction from the coordination target. As can be seen from the figure, the deviation of the thermal power unit and the flywheel energy storage gradually reaches synchronous convergence in the iteration process, indicating that the two reach an agreement under the global target, solving the cross-time scale coordination question of the slow dynamic of the thermal power and the fast dynamic of the flywheel, and being able to effectively coordinate the control amount of the thermal power and the flywheel and meet the consistency requirement of the frequency modulation demand.

[0075] S6, real-time monitoring of the frequency change rate of the power system, dynamically adjusting the virtual inertia parameter of the flywheel energy storage according to the frequency change rate, and generating the flywheel dynamic compensation power matched with the virtual inertia parameter.

[0076] In some embodiments, the dynamic adjustment rule of the virtual inertia parameter comprises:

[0077] When the frequency change rate of the power system is greater than a preset threshold, the virtual inertia parameter is adjusted to a preset multiple of the virtual inertia base value; and when the frequency change rate of the power system is less than or equal to the preset threshold, the virtual inertia parameter is adjusted to the virtual inertia base value. The virtual inertia parameter is used to increase the system inertia, suppress the frequency mutation, and maintain the base inertia under normal working conditions, and only increase the inertia under emergency working conditions, avoiding continuous high-load operation of the flywheel.

[0078] For example, assuming that the preset threshold is 0.1 Hz / s and the preset multiple is 1.5, the expression of the virtual inertia parameter is as follows:

[0079] ;

[0080] wherein, H f (t) represents the virtual inertia parameter, H base represents the virtual inertia base value, which can be set to 0.5, represents the frequency change rate, which is obtained by real-time measurement.

[0081] In some embodiments, the calculation formula of the flywheel dynamic compensation power is as follows:

[0082] ;

[0083] ;

[0084] wherein, represents the flywheel dynamic compensation power at t time, represents a compensation gain, and S represents a system reference capacity, represents a frequency change rate. The flywheel dynamic compensation power is directly related to the frequency change rate, and the flywheel can provide reverse power (such as releasing energy when the frequency suddenly drops) in milliseconds to quickly suppress disturbances.

[0085] S7, obtaining a thermal power unit execution instruction according to the coordinated thermal power reference instruction and the thermal power unit control input, and obtaining a flywheel energy storage execution instruction according to the coordinated flywheel reference instruction and the flywheel dynamic compensation power.

[0086] Specifically includes:

[0087] The coordinated thermal power reference instruction and the thermal power unit control input are subjected to dead zone processing to obtain the thermal power unit execution instruction, and the calculation formula is as follows:

[0088] ;

[0089] wherein, represents the thermal power unit execution instruction, represents the final thermal power reference instruction output in step S5, represents an actual thermal power unit input, and DeadZone represents a dead zone function, which is used to suppress small fluctuations within ±2% to avoid frequent adjustment of the thermal power unit due to noise or measurement error.

[0090] The coordinated flywheel reference instruction is superimposed with the flywheel dynamic compensation power and subjected to state of charge safety limiting processing to obtain the flywheel energy storage execution instruction, and the calculation formula is as follows:

[0091] ;

[0092] ;

[0093] wherein, represents the flywheel energy storage execution instruction, represents the final flywheel reference instruction output in step S5, and SOC t represents a safety scaling factor, which automatically reduces the output when the SOC approaches the lower limit to prevent over-discharge.

[0094] The frequency modulation control is respectively performed on the thermal power generating unit and the flywheel energy storage device according to a thermal power generating unit execution instruction and a flywheel energy storage execution instruction.

[0095] Figure 3 is a comparison chart of the thermal power-flywheel collaborative and independent frequency modulation effect provided by the embodiment of the present application, referring to Figure 3 The absolute value of the frequency deviation of the collaborative frequency modulation (green solid line) is obviously lower than that of the independent frequency modulation mode, and the thermal power independent frequency modulation (red dotted line) has a slow dynamic defect: initial response lag (0~10 seconds deviation maximum), and low frequency fluctuation (0.2~0.4 Hz) still exists in the steady state stage, which is limited by mechanical inertia. The flywheel independent frequency modulation (blue dotted line) has a capacity limitation: rapid response in the initial stage (10~20 seconds deviation decreases rapidly), but the deviation rises to 0.3 Hz in the later stage due to insufficient energy storage capacity (SOC limitation). As can be seen from the chart, the smoothness of the collaborative frequency modulation curve is significantly better than that of the independent mode, and the collaborative frequency modulation suppresses the frequency secondary drop caused by the slow dynamic of the thermal power, avoiding the risk of system instability.

[0096] The scheme builds a joint dynamic model of thermal power and flywheel energy storage, separates the slow and fast dynamic characteristics of the two based on state space, designs control objectives at minute and second time granularities respectively using a hierarchical optimization framework, realizes consistent matching of cross-scale power instructions by combining an asynchronous coordination algorithm, solves the control conflict problem caused by mismatched dynamic response; the flywheel side introduces a virtual inertia segmented adjustment mechanism, dynamically improves the inertia support strength according to the real-time frequency change rate, and enhances the adaptability of the system to inertia loss scenarios by fusing compensation power generation and energy storage output. At the same time, the state of charge safety constraint and life loss cost term of the energy storage are embedded in the optimization objective, and the output boundary is adjusted by combining a dynamic scaling factor, realizing the collaborative balance of frequency modulation demand and energy storage health state.

[0097] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present application.

Claims

1. A method for coordinated frequency regulation control of a flywheel energy storage-assisted thermal power unit, characterized in that, The method includes the following steps: S1. Construct a joint dynamic model of thermal power unit and flywheel energy storage, wherein the joint dynamic model includes the state equation of thermal power unit and the state equation of flywheel energy storage. The expression for the state equation of the thermal power unit is as follows: ； in, T represents the rate of change of the output power of a thermal power unit with time. th Let x1(t) represent the time constant of the thermal power unit, and let K represent the output power of the thermal power unit at time t. th U represents the gain coefficient of thermal power units. th (t) represents the control input of the thermal power unit at time t, d1(t) represents the first renewable energy disturbance term at time t, and t represents time; The expression for the flywheel energy storage state equation is as follows: ； in, T represents the rate of change of flywheel energy storage output power over time. f Let x2(t) represent the flywheel energy storage time constant, x2(t) represent the flywheel energy storage output power at time t, and K represent the flywheel energy storage output power. f U represents the flywheel energy storage gain coefficient. f (t) represents the flywheel energy storage control input at time t, and d2(t) represents the second renewable energy disturbance term at time t; S2. Based on the state matrix eigenvalues ​​of the joint dynamic model, extract the dominant dynamic characteristics of the thermal power unit and the dominant dynamic characteristics of the flywheel energy storage. The calculation formula is as follows: ； Where A represents the state matrix, and the dominant dynamic characteristic λ of the thermal power unit can be obtained from the state matrix. th = Flywheel energy storage dominates dynamic characteristics λ f = ; S3. Based on the time constant of the dominant dynamic characteristics of the thermal power unit, set the first cycle time granularity of the thermal power layer optimization, and based on the time constant of the dominant dynamic characteristics of the flywheel energy storage, set the second cycle time granularity of the flywheel layer optimization. S4. Construct the optimization objective function for the thermal power layer based on the first cycle time granularity, and construct the optimization objective function for the flywheel layer based on the second cycle time granularity; S5. Define robust consistency constraints for the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer. Iteratively optimize the optimization objective function of the thermal power layer and the optimization objective function of the flywheel layer using an asynchronous coordination algorithm, and output the coordinated thermal power reference command and flywheel reference command. S6. Monitor the frequency change rate of the power system in real time, dynamically adjust the virtual inertia parameter of the flywheel energy storage according to the frequency change rate, and generate the flywheel dynamic compensation power that matches the virtual inertia parameter. S7. Obtain the thermal power unit execution command based on the coordinated thermal power reference command and the thermal power unit control input; obtain the flywheel energy storage execution command based on the coordinated flywheel reference command and the flywheel dynamic compensation power.

2. The method for coordinated frequency regulation control of a flywheel energy storage-assisted thermal power unit according to claim 1, characterized in that, In step S3, the first cycle time granularity is a preset multiple of the time constant of the thermal power unit, and the second cycle time granularity is a preset multiple of the time constant of the flywheel energy storage.

3. The method for coordinated frequency regulation control of a flywheel energy storage-assisted thermal power unit according to claim 2, characterized in that, In step S4, the objective function for optimizing the thermal power stratum is expressed as follows: ； Where n represents the nth first time window, the length of the first time window is the time granularity of the first period, and u th (n) represents the optimization instructions for the thermal power layer in the nth first time window, u th (n-1) represents the optimization instruction of the thermal power layer in the (n-1)th first time window, N represents the total number of first time windows, a represents the quadratic term coefficient of the power generation cost of the thermal power unit, b represents the thermal power ramp-up penalty coefficient, ρ represents the coordination weight coefficient, and z(n) represents the coordination variable generated by the flywheel layer in the nth first time window.

4. The method for coordinated frequency regulation control of a flywheel energy storage-assisted thermal power unit according to claim 2, characterized in that, In step S4, the objective function for optimizing the flywheel layer is expressed as follows: ； Where m represents the m-th second time window, and the length of the second time window is the time granularity of the second period, u f (m) represents the optimization instruction of the flywheel layer in the m-th second time window, M represents the total number of second time windows, β represents the flywheel energy storage loss coefficient, μ represents the SOC penalty coefficient, SOC(m) represents the flywheel energy storage state of charge in the m-th second time window, and ρ represents the coordination weight coefficient. This represents the coordination variable generated by the thermal power layer in the m-th second time window.

5. The method for coordinated frequency regulation control of a flywheel energy storage-assisted thermal power unit according to claim 1, characterized in that, In step S5, the robust consistency constraints for the optimization objective functions of the thermal power layer and the flywheel layer are defined as follows: ； Where M represents the total number of second time windows, m represents the m-th second time window, and u f (m) represents the optimization instructions for the flywheel layer in the m-th second time window, u th (n) represents the optimization instructions for the thermal power layer in the nth first time window, Δ max This indicates the maximum permissible power deviation.

6. The method for coordinated frequency regulation control of a flywheel energy storage-assisted thermal power unit according to claim 5, characterized in that, In step S5, during the iterative optimization of the objective functions of the thermal power layer and the flywheel layer using the asynchronous coordination algorithm, the process also includes updating the coordination variables. The formula for updating the coordination variables is as follows: ； Where z represents the coordination variable generated by the flywheel layer or the coordination variable generated by the thermal power layer, z k+1 This represents the coordination variable generated by the flywheel layer or the thermal power layer in the (k+1)th iteration, where k represents the iteration number. This represents the optimization instruction for the thermal power layer in the (k+1)th iteration of the first time window (nth time window), where M represents the total number of second time windows. ) represents the optimization instruction of the flywheel layer in the kth iteration of the mth second time window.

7. The method for coordinated frequency regulation control of a flywheel energy storage-assisted thermal power unit according to claim 1, characterized in that, In step S6, the dynamic adjustment rules for the virtual inertia parameter include: When the rate of change of the power system frequency is greater than a preset threshold, the virtual inertia parameter is adjusted to a preset multiple of the virtual inertia base value; when the rate of change of the power system frequency is less than or equal to the preset threshold, the virtual inertia parameter is adjusted to the virtual inertia base value.

8. The method for coordinated frequency regulation control of a flywheel energy storage-assisted thermal power unit according to claim 1, characterized in that, In S6, the calculation formula for the flywheel dynamic compensation power is as follows: ； in, This represents the flywheel dynamic compensation power at time t. Indicates compensation gain. It represents the rate of change of frequency.

9. The method for coordinated frequency regulation control of a flywheel energy storage-assisted thermal power unit according to claim 1, characterized in that, S7 specifically includes: performing dead-time processing on the coordinated thermal power reference command and the thermal power unit control input to obtain the thermal power unit execution command; The coordinated flywheel reference command is superimposed with the flywheel dynamic compensation power and then subjected to state-of-charge safety limiting processing to obtain the flywheel energy storage execution command.

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