Partition control method based on hybrid energy storage life economy and frequency modulation limit

Abstract

The invention discloses a partition control method based on hybrid energy storage life economy and frequency modulation limit, and belongs to the technical field of thermal power-energy storage combined frequency modulation. According to the method, dynamic equilibrium quotation and each energy storage performance representation are established by using real-time SOC to serve as an upper layer model, energy type energy storage optimal life evaluation is provided, an energy storage charging and discharging switching model is constructed, frequent switching of energy type energy storage is limited, and the life is prolonged; the bottom model constructs a power type energy storage frequency modulation limit standard, introduces multi-target constraints, proposes a hybrid energy storage operation scheme suitable for a full scene, employs evaluation indexes, carries out the frequency modulation effect evaluation of the provided frequency modulation control model from the adjustment rate, precision and response time, improves the net income, reduces the service life loss and frequency deviation of a battery, and improves the reliability of the system. The frequency modulation reliability and sustainability of regional energy storage can be improved; the method has the advantages of being scientific, reasonable, high in applicability, good in effect and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal power-energy storage combined frequency regulation, and in particular relates to a zoning control method based on hybrid energy storage life economy and frequency regulation limit. Background Art

[0002] At present, the large-scale grid connection of new energy represented by wind and solar power has brought severe challenges to the frequency security of my country's power system due to its randomness and intermittency. As the main force of frequency regulation, thermal power units are difficult to meet the frequency accuracy and speed requirements due to their own characteristics. The energy storage system has the characteristics of rapid response and precise tracking, and can efficiently assist thermal power units in frequency regulation. With the continuous refinement of power system requirements, a single type of energy storage has been difficult to meet the requirements of configuration flexibility, safety, response speed, service life, economic benefits, etc. Therefore, hybrid energy storage came into being, such as battery-flywheel hybrid energy storage, which can not only improve the frequency regulation capability of energy storage, but also reduce the life loss of battery energy storage. However, the current hybrid energy storage does not take into account the mutual influence of the frequency regulation performance between each energy storage, and the frequency regulation mode of hybrid energy storage is difficult to maintain at a long time scale, which fails to fully reflect the value law and regulatory role of hybrid energy storage. The large-scale grid connection of new energy and the lack of traditional frequency regulation capabilities have led to the problem that frequency security and the economic benefits of frequency regulation resources cannot be taken into account at the same time.

[0003] Therefore, a new technical solution is urgently needed in the prior art to solve this problem. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for controlling frequency regulation limit zoning based on the life economy of hybrid energy storage to solve the technical problem that large-scale grid connection of new energy and the lack of traditional frequency regulation capacity lead to the inability to balance frequency safety and economic benefits of frequency regulation resources.

[0005] A method for controlling the partitioning of hybrid energy storage life economy and frequency modulation limit includes the following steps, which are performed in sequence:

[0006] Step 1: Establish a hybrid energy storage combined frequency regulation system and obtain hybrid energy storage output, battery output and flywheel output;

[0007] Step 2: Formulate a double-layer optimization allocation model for hybrid energy storage to assist thermal power unit frequency regulation, wherein the double-layer optimization allocation model includes a hybrid energy storage upper-layer scheduling model and a hybrid energy storage bottom-layer control strategy;

[0008] 1) The hybrid energy storage upper-layer scheduling model performs real-time state optimization of the hybrid energy storage, including:

[0009] ① Establish a battery life loss model based on real-time energy storage state of charge (SOC) and equivalent life cycle to evaluate the optimal life of battery energy storage;

[0010] ②Provide SOC dynamic balance quotation;

[0011] ③ Characterize the hybrid energy storage performance;

[0012] 2) According to the formulated hybrid energy storage underlying control strategy, combined with AGC instructions, thermal power unit output and real-time optimization status of hybrid energy storage, frequency modulation partition control is performed to obtain hybrid energy storage frequency modulation output and battery energy storage new energy dispatching output;

[0013] Step 3: Establish a hybrid energy storage transaction decision model, and obtain a hybrid energy storage operation plan suitable for all scenarios by solving the objective function of the model;

[0014] 1) The objective function is:

[0015]

[0016] Where: is the frequency modulation benefit at the current moment; C t neg is the power revenue at the current moment; C cost,t is the total cost at the current moment;

[0017] in,

[0018] Where: The cost of frequency regulation capacity for hybrid energy storage; The mileage cost of frequency regulation for hybrid energy storage;

[0019]

[0020] Where: The capacity and mileage subsidy income obtained by flywheel energy storage participating in frequency regulation during the frequency regulation period. The capacity and mileage subsidy income obtained by battery energy storage participating in frequency regulation during the frequency regulation cycle. is the frequency regulation capacity compensation price before correction, is the flywheel frequency modulation power at the current moment, The revised frequency adjustment mileage compensation price, To store energy in the flywheel and adjust the mileage; is the revised frequency regulation capacity compensation price, is the battery frequency modulation power at the current moment, The price of compensation for frequency adjustment mileage before correction. Frequency modulation for battery storage;

[0021]

[0022] Where: The electricity revenue from dispatching battery energy storage; η dc is the battery charging and discharging efficiency; ce is the on-grid electricity price, Charging power for the battery, is the battery discharge power;

[0023] 2) Establish constraints;

[0024] ①Battery energy storage aims to increase lifespan;

[0025] ②Battery energy storage aims to ensure the safety of grid frequency;

[0026] ③ Hybrid energy storage only participates in the frequency regulation service market;

[0027] ④Other constraints;

[0028] Step 4: Establish a hybrid energy storage efficiency index as an evaluation index. The hybrid energy storage efficiency index is mainly reflected in the frequency regulation performance. The frequency regulation performance is evaluated by evaluating the AGC instructions that can be achieved by the frequency regulation assistance of the thermal power unit.

[0029] The mixed energy storage output in step 1 is specifically:

[0030] The difference between the AGC command and the output of the thermal power unit is used as the AGC command of the hybrid energy storage in this area, then:

[0031]

[0032] Where: is the hybrid energy storage frequency modulation power; P G,t Frequency modulation power for thermal power units; is the AGC instruction; P t en Trading power for energy storage; It is the remaining power of hybrid energy storage at the current moment.

[0033] The battery output and flywheel output in step 1 are specifically:

[0034] The frequency modulation includes flywheel frequency modulation output and battery frequency modulation output, as well as the battery charging and discharging energy trading to increase the battery life.

[0035]

[0036] Where: The flywheel frequency modulation power; is the battery frequency modulation power, P is the charge and discharge power of the battery energy storage under SOC recovery.dc,rate is the rated power of the battery.

[0037] In step 2, the optimal life of battery energy storage is evaluated, specifically:

[0038] The throughput method is used to calculate the battery life, and a life evaluation model for battery energy storage is built. The maximum number of charge and discharge cycles that can be achieved at the charge and discharge depth x is fitted into a polynomial. The relationship of the life evaluation model for battery energy storage is as follows:

[0039] N x =-12894x 5 +37860x 4 -42699x 3 +23528x 2 -6785.4x+12446.2;

[0040] Where: N x is the number of cycle life of battery energy storage when the depth of charge and discharge is x;

[0041] Calculate the maximum throughput power corresponding to the depth of charge and discharge of the battery energy storage. According to the maximum number of charge and discharge cycles under x and the power value that can be handled in one charge and discharge cycle, calculate and obtain the total power that the battery can handle when running at x during its life cycle:

[0042]

[0043] Where: E x E is the total amount of electricity that the battery energy storage can handle when operating at x during its life cycle; 1 E is the amount of electricity that the battery can handle in one charge and discharge cycle when the battery is running at x time; dcrate The rated capacity of the battery energy storage;

[0044] By quantifying the relationship between the depth of discharge, discharge range and equivalent cycle life, a battery energy storage life loss model based on real-time SOC state and equivalent life cycle number is constructed:

[0045]

[0046] Where: N x N is the number of energy storage life cycles at the current charge and discharge depth, max is the number of energy storage life cycles at the maximum charge and discharge depth; x ref is the equivalent life cycle number; SOC dc,t The current SOC of the battery energy storage, SOC dc,ref is the equivalent SOC state, μ 1 , μ 2 is a constant provided by the battery manufacturer;

[0047] Establish the equivalent life cycle number of battery energy storage at different discharge depths (DOD) in each SOC range:

[0048]

[0049] Where: n eq is the number of unit equivalent life cycles;

[0050] Through the battery energy storage life loss model, the relationship between SOC and unit transfer energy is obtained:

[0051]

[0052] Where: e SOC,t Transfer energy for the current SOC state unit; k p is a constant, and is obtained by fitting the relationship between the number of energy storage cycles and the depth of discharge using the actual operating data provided by the battery manufacturer.

[0053] The step 2 is to carry out SOC dynamic balance quotation, specifically:

[0054] The energy storage income is limited by the SOC dynamic equilibrium quotation coefficient to achieve the effect of constraining the frequency modulation output. To ensure the high power of flywheel energy storage, the non-limit range of flywheel energy storage is set to 0.1-0.9. To ensure the high capacity of battery energy storage, the non-limit range of battery energy storage is set to 0.2-0.8. Based on the evaluation of the optimal life of battery energy storage, the optimal working state of energy storage SOC is set to 0.4-0.6;

[0055] The SOC dynamic balance quotation is based on the real-time energy storage SOC dynamic response to control energy storage, which is:

[0056] When charging:

[0057]

[0058] In discharge state:

[0059]

[0060] Where: SOC k,low , SOC k,high is the minimum and maximum thresholds under the optimal state of SOC, is the adjustment factor during charging, SOC k,t is the SOC of energy storage at time t, is the adjustment factor during discharge.

[0061] The hybrid energy storage performance is characterized in step 2, specifically:

[0062] Frequency regulation performance is introduced to characterize the different frequency regulation characteristics of hybrid energy storage. The power characteristic coefficient is used to quantify the impact of the frequency regulation mileage of the frequency regulation resources during the frequency regulation process on the flywheel frequency regulation benefits. The capacity characteristic coefficient is used to characterize the impact of the change in the frequency regulation demand capacity of the frequency regulation resources during the frequency regulation process on the battery frequency regulation benefits.

[0063] The frequency regulation performance coefficient of flywheel energy storage and battery energy storage is established based on the historical frequency regulation performance index, as shown in the following formula:

[0064]

[0065] Where: Kp is the frequency modulation factor under the historical frequency modulation performance index; k Kp is the historical frequency regulation performance index of each energy storage; sat Kp is the historical frequency modulation performance saturation index; min It is the minimum index of historical frequency modulation performance;

[0066] In the above formula, k represents the energy storage type. If k is replaced by dc, the above formula is the frequency regulation performance coefficient of battery energy storage. If k is replaced by fl, the above formula is the frequency regulation performance coefficient of flywheel energy storage.

[0067] The power characteristic coefficient of flywheel energy storage is:

[0068]

[0069] Where: fl is the flywheel relaxation factor; t fl is the flywheel frequency modulation response time; E flrate is the rated capacity of the flywheel energy storage; is the maximum output of the flywheel at the current moment, Δt is the time interval;

[0070] Based on the power characteristic coefficient, the optimized compensation price for frequency regulation mileage at any time in the flywheel energy storage frequency regulation auxiliary service market is obtained as follows:

[0071]

[0072] Where: The price for compensation of frequency adjustment mileage after correction; The price for compensation of frequency adjustment mileage before correction;

[0073] The capacity characteristic coefficient of battery energy storage is:

[0074]

[0075] Where: dc is the battery relaxation factor; t dc The frequency modulation response time of the battery; The maximum output of the battery at the current moment; The maximum output of the battery at the current moment;

[0076] Based on the capacity characteristic coefficient, the frequency regulation optimization clearing price at any time in the battery energy storage frequency regulation auxiliary service market is obtained as follows:

[0077]

[0078] Where: The price for compensation of frequency regulation capacity after correction; It is the price for frequency regulation capacity compensation before correction.

[0079] The underlying control strategy of the hybrid energy storage in step 2 is specifically as follows:

[0080] ① If the flywheel energy storage is sufficient to meet the frequency regulation demand, the control strategy aims to improve the battery life. The flywheel is used alone for frequency regulation output, so that it can give full play to the advantages of power-type energy storage and meet the frequency regulation demand. The battery energy storage participates in the electric energy market based on the battery energy storage life assessment model to obtain electric energy benefits.

[0081] ② If the remaining frequency regulation capacity of the flywheel is insufficient, the control strategy aims to participate in frequency regulation to ensure the frequency safety of the power grid, with the dynamic balance of each energy storage SOC and the frequency regulation capacity of the hybrid energy storage as limitations. The battery energy storage is forced to participate in some small interference fluctuations, extending the overall frequency regulation capacity of the hybrid energy storage.

[0082] The expressions of the hybrid energy storage frequency modulation output and the battery energy storage new energy dispatching output in step 2 are as follows:

[0083] They are 0-1 variables for hybrid energy storage charging and discharging, and the relationship between them is:

[0084]

[0085] It is stipulated that battery energy storage can only work in charging state or discharging state at the same time;

[0086] The output of battery storage at time t is:

[0087]

[0088] Where: P b,t Total output for battery storage; The charging and discharging power of the battery involved in scheduling; The charging and discharging power of the battery participating in frequency modulation; A 0-1 variable to charge the battery; A 0-1 variable for battery discharge;

[0089] The battery energy storage response to the new energy dispatch power at time t is:

[0090]

[0091] Where: dispatching power for battery energy storage;

[0092] The total power of hybrid energy storage participating in new energy dispatch and frequency regulation at time t is:

[0093]

[0094] Where: P t W It is the total output of hybrid energy storage; The charge and discharge power of the flywheel involved in scheduling; is a 0-1 variable for flywheel discharge; A 0-1 variable that charges the flywheel.

[0095] The constraints in step 3 are specifically:

[0096] ① Constraints on battery energy storage with the goal of increasing lifespan, specifically:

[0097] Battery energy storage bidding power constraints: At the current moment, the power of battery energy storage participating in the electric energy market and frequency regulation auxiliary service market meets the maximum, minimum charging and discharging power and rated power constraints:

[0098]

[0099] Where: P dc,max is the remaining maximum frequency modulation power when the battery SOC limit is close to 0.9, P dc,min It is the remaining maximum frequency modulation power when the battery SOC limit is close to 0.1, is the battery discharge power, is the frequency modulation power when the battery is discharged, P dc,rate is the battery rated power, Charging power for the battery, FM power when charging the battery;

[0100] Battery storage capacity constraints:

[0101] Based on the battery life assessment, the optimal SOC limit capacity is set:

[0102]

[0103] Where: E dc,t is the battery capacity at the current moment; S dc_ The best upper limit SOC for battery life evaluation; S dc_The optimal lower limit SOC for battery life evaluation; η dc The battery charging and discharging efficiency;

[0104] Battery energy storage cycle life constraint: obtained through the battery energy storage life loss model of real-time SOC state and equivalent life cycle number;

[0105] ② The constraints of battery energy storage to ensure grid frequency safety are as follows:

[0106] Battery storage capacity constraints:

[0107]

[0108] Where: SOC dc,max , SOC dc,max The maximum and minimum SOC states of the battery;

[0109] ③ Hybrid energy storage only participates in the frequency regulation service market, specifically:

[0110] Battery storage capacity constraints:

[0111]

[0112] Where: E i,t is the battery capacity at the current moment, SOC i,max is the maximum SOC value, SOC i,min is the minimum SOC value, E i,rate is the rated capacity, is the frequency modulation power during charging at the current moment, η i is the charge and discharge efficiency;

[0113] ④Other constraints, specifically:

[0114] Frequency modulation power balance constraints:

[0115]

[0116] FM power constraints:

[0117]

[0118] Where: is the energy storage frequency modulation power during discharge at the current moment, The energy storage frequency modulation power during charging at the current moment, is the minimum frequency modulation power of energy storage during charging at the current moment, P k,rate is the energy storage rated power, The maximum frequency modulation power of energy storage during charging at the current moment;

[0119] SOC constraints:

[0120]

[0121] Where: SOC k,min is the minimum energy storage SOC, SOC k,max is the maximum energy storage SOC, η k For energy storage charging and discharging efficiency, is the energy storage discharge power at the current moment, The energy storage charging power at the current moment;

[0122] Due to the characteristics of battery energy storage life, the operation duration is used as the switching charge and discharge constraint. The battery energy storage charge and discharge switching flexibility constraint is divided into the maximum charge and discharge cycle constraint and the charge and discharge duration constraint.

[0123] The maximum number of charge and discharge cycles is constrained to:

[0124]

[0125] In the formula: σ is the charge and discharge symbol; k is the charge and discharge time; is the change of discharge state; To change to a discharge state; The charging state changes; Change to charging state; N 0 is the maximum number of charge and discharge cycles;

[0126] Frequency modulation charging and discharging operation duration constraints:

[0127]

[0128] Where: T c 、T d To limit the charging and discharging time; is the time adjustment factor; TC and TD are the duration of charge and discharge; They are respectively changed into charging state and changed into discharging state; They are respectively the duration of charging and the duration of discharging.

[0129] The regulation performance in step 4 includes three factors: regulation rate, regulation accuracy and response time;

[0130] The evaluation index expression is as follows:

[0131]

[0132] Where: It is an evaluation index to measure the regulation performance of the i-th unit during the j-th regulation process; and are the adjustment rate, accuracy and response time of the jth adjustment of the i-th unit respectively;

[0133] The frequency regulation performance evaluation of the AGC instructions that can be achieved by the thermal power unit frequency regulation assistance is carried out as follows:

[0134] ① Frequency modulation rate

[0135] The regulation rate refers to the rate at which the unit responds to the setpoint command, which is divided into rising rate and falling rate. The calculation process of the jth regulation rate of the i-th unit is as follows:

[0136] The actual adjustment rate calculation formula is as follows:

[0137]

[0138] Where: v i,j is the jth actual regulation rate of unit i, in MW / minute; P Ei,j is the output at the end of the response process, in MW; P Si,j is the output when it starts to move, in MW; T Ei,j It's time to end, T Si,j It's time to start, P di,j is the critical power of the start-stop grinding mill of the jth adjustment, in MW; T di,j is the actual time consumed by the jth adjustment of starting and stopping the grinding mill;

[0139] If the unit does not meet the typical AGC set point control process, that is, the unit fails to enter the target dead zone, the regulation rate is the unit output at the end of the instruction minus the active change of the output at the time of crossing the dead zone divided by the required time;

[0140] The calculation formula of the regulation rate regulation index is:

[0141]

[0142] Where: v N,i is the standard regulation rate of unit i, in MW / min;

[0143] ②Adjustment accuracy

[0144] The regulation accuracy refers to the difference between the actual output and the set point output after the unit response is stable. The method of obtaining it is: integrate the absolute value of the difference between the actual output and the command, and then divide the integral by the integration time to obtain the regulation deviation for the period. The formula is as follows:

[0145]

[0146] Where: P i,j (t) is the actual output during the period, P i,j Get the set point command value for this period, T Ei,jis the end of the time period, T Si,j is the starting point of the time period;

[0147] If the unit fails to enter the target dead zone, the regulation accuracy is the minimum value of the deviation between the actual output and the target output during the period from the time when the unit steps out of the dead zone in the same direction to the time when the command ends:

[0148]

[0149] Where: The allowable deviation of regulation is 1% of the rated active power of the unit;

[0150] ③Response time

[0151] Response time refers to the time it takes for the unit to reliably step out of the frequency regulation dead zone consistent with the regulation direction at the original output point after the EMS system issues a command. The formula is as follows:

[0152]

[0153] Where: is the time for the i-th unit to leave the initial regulation dead zone during the j-th regulation process, T 1 T is the time to leave the regulation dead zone. 0 The time when the unit starts to produce power, is the time of leaving the last regulation dead zone of the i-th unit during the j-th regulation process, T 6 is the time to leave the grinding stop point, T 5 is the time when the AGC control program issues a new set point command to the unit, t i,j is the response time of the jth AGC unit of the i-th unit; the standard AGC response time of thermal power units is less than 1min;

[0154] The above and If the calculated value is less than 0.1, it is taken as 0.1 and the evaluation index is used. Calculation of and If one of the calculated values ​​is greater than 2, then none of the three calculated values ​​will be evaluated. calculation; assessment and If the calculated values ​​are all within the range of [0.1, 2], the evaluation index is Calculation.

[0155] Through the above design scheme, the present invention can bring the following beneficial effects:

[0156] The present invention uses real-time SOC to establish a dynamic equilibrium quotation and each energy storage performance characterization as the upper model, and at the same time proposes an optimal life assessment of energy-type energy storage, constructs an energy storage charge and discharge switching model, limits the frequent switching of energy-type energy storage, and extends its life; the underlying model constructs a power-type energy storage frequency regulation limit standard, introduces multi-objective constraints, and proposes a hybrid energy storage operation plan suitable for all scenarios. The evaluation index is used to evaluate the frequency regulation effect of the proposed frequency regulation control model from the perspective of regulation rate, accuracy and response time, which improves the net profit, reduces battery life loss and frequency deviation, and is beneficial to increasing the frequency regulation reliability and sustainability of regional energy storage; it has the advantages of scientific and reasonable methods, strong applicability, and good effects.

[0157] The present invention effectively solves the problem in the prior art that the mutual influence between the life loss of battery energy storage and the frequency regulation performance between various energy storages is not fully considered, the frequency regulation mode of hybrid energy storage cannot be maintained on a long time scale, and the value law and regulatory role of hybrid energy storage are not fully reflected. BRIEF DESCRIPTION OF THE DRAWINGS

[0158] The present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0159] Figure 1 A schematic diagram of a hybrid energy storage frequency modulation structure in a hybrid energy storage life economy and frequency modulation limit zoning control method according to the present invention;

[0160] Figure 2 A double-layer control framework diagram of hybrid energy storage in a method for controlling hybrid energy storage life economy and frequency modulation limit partitioning according to the present invention;

[0161] Figure 3 A flow chart of a hybrid energy storage control strategy in a hybrid energy storage life economy and frequency modulation limit zoning control method according to the present invention;

[0162] Figure 4 It is the frequency modulation power diagram of model 1 and model 2 in the example analysis of the present invention;

[0163] Figure 5 It is the hybrid energy storage power diagram of Model 1 and Model 2 in the example analysis of the present invention;

[0164] Figure 6 It is the SOC dynamic balance quotation diagram in the example analysis of the present invention;

[0165] Figure 7 The SOC variation diagram of Model 1 and Model 2 in the example analysis of the present invention;

[0166] Figure 8 It is a diagram of frequency modulation output and SOC variation of different energy storage configuration schemes in the example analysis of the present invention. DETAILED DESCRIPTION

[0167] The present invention will be further described in detail below in conjunction with specific implementation modes. The following examples are used to illustrate the present invention, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0168] like Figures 1 to 3 As shown, the present invention is a method for controlling the life economy and frequency modulation limit partition of hybrid energy storage. First, a hybrid energy storage combined with frequency modulation system is established. Then, a hybrid energy storage double-layer optimization allocation strategy is constructed. Then, the real-time state optimization layer and the frequency modulation partition control layer are designed respectively. Then, a hybrid energy storage transaction decision model is constructed. By designing the constraint conditions of the partition control layer, the model is solved, and finally the hybrid energy storage frequency modulation output and the battery power output are obtained. The specific steps are as follows:

[0169] Step 1: Establish a hybrid energy storage and frequency regulation system

[0170] A hybrid energy storage combined frequency regulation system is established to realize the AGC command distribution between thermal power units and hybrid energy storage, and then the AGC commands distributed by the hybrid energy storage are divided into the flywheel frequency regulation output and battery frequency regulation output participating in the frequency regulation, as well as the charging and discharging energy transaction of the battery to increase its life. The specific relationship is as follows:

[0171]

[0172] Where: is the hybrid energy storage frequency modulation power; P G,t Frequency modulation power for thermal power units; is the AGC instruction; P t en Trading power for energy storage; The remaining power of the hybrid energy storage at the current moment; The flywheel frequency modulation power; is the battery frequency modulation power, Restore the charge and discharge power under SOC for battery energy storage.

[0173] The relationship diagram described in step 1 is shown in Figure 1 .

[0174] Step 2: construct a hybrid energy storage double-layer optimization allocation strategy;

[0175] First, the real-time status optimization layer is designed;

[0176] The first step is to establish a battery life assessment model by fitting the historical data with a polynomial of the maximum number of charge and discharge cycles that the battery storage can achieve at the charge and discharge depth x:

[0177] N x =-12894x 5 +37860x 4 -42699x3 +23528x 2 -6785.4x+12446.2 (4);

[0178] Where: N x is the number of cycles of battery energy storage when the depth of charge and discharge is x; the total amount of electricity that the battery can handle when running at x during its life cycle can then be calculated:

[0179]

[0180] Where: E x E is the total amount of electricity that the battery energy storage can handle when operating at x during its life cycle; 1 E is the amount of electricity that the battery can handle in one charge and discharge cycle when the battery is running at x time; dcrate is the rated capacity of the battery energy storage; in view of the problem that different discharge intervals of the battery energy storage discharge cycle will also reduce the energy storage life, a battery life loss model considering the real-time SOC state and the equivalent life cycle number is proposed:

[0181]

[0182] Where: n eq Is the number of unit equivalent life cycles.

[0183] Based on the real-time SOC state and the battery life loss model of equivalent life cycle, the relationship between SOC and unit transfer energy is obtained.

[0184]

[0185] Where: e SOC,t Transfer energy for the current SOC state unit; k p is a constant and can be obtained by fitting the relationship between the number of energy storage cycles and the depth of discharge using the actual operating data provided by the battery manufacturer.

[0186] The second step is to design a SOC dynamic equilibrium quotation strategy, which is to compare the real-time SOC state of the energy storage with the optimal working state of the energy storage SOC, and set the optimal working state of the battery energy storage SOC to 0.4-0.6, and the optimal working state of the flywheel energy storage SOC to 0.1-0.9. When the AGC instruction is in the charging state, when the energy storage SOC state is less than the minimum limit of the SOC optimal working state, the energy storage power demand is positively correlated with the frequency regulation state, and takes priority over the energy storage charging, while participating in the frequency regulation service, taking into account the recovery of the energy storage SOC; and when the SOC state of the energy storage is greater than the minimum limit of the SOC optimal working state and less than the maximum limit of the SOC optimal working state, the energy storage is in the optimal state, and the energy storage cost and benefit caused by the SOC are not considered. When the SOC state is greater than the maximum limit under the optimal state, the energy storage power demand is negatively correlated with the frequency regulation state, and continuous charging will cause the energy storage to reach an over-limit state, so at this stage, coordinated cooperation between hybrid energy storage is required. Conversely, the situation in the discharge state is similar. Specifically:

[0187] Discharge status:

[0188]

[0189] Charging status:

[0190]

[0191] Where: SOC k,low , SOC k,high These are the minimum and maximum thresholds under the optimal SOC state.

[0192] The third step is to establish the performance characterization of hybrid energy storage. The frequency regulation benefits of hybrid energy storage are mainly frequency regulation mileage and frequency regulation capacity benefits. In order to solve the problem of reasonable compensation for fast and slow frequency regulation resources, the frequency regulation performance is introduced to characterize the different frequency regulation characteristics of hybrid energy storage. The flywheel energy storage has high power, and the power characteristic coefficient is used to quantify the impact of frequency regulation mileage on the flywheel frequency regulation benefits; the battery energy storage has high capacity, and the capacity characteristic coefficient is used to characterize the impact of changes in frequency regulation demand capacity on battery frequency regulation benefits. The performance coefficients of flywheel energy storage and battery energy storage are established based on historical frequency regulation performance indicators, as shown in the following formula:

[0193]

[0194] Where: Kp is the frequency modulation factor under the historical frequency modulation performance index; k is the historical frequency regulation performance index of each energy storage; k is the energy storage type; Kp sat Kp is the historical frequency modulation performance saturation index; min It is the minimum indicator of historical frequency modulation performance.

[0195] The energy storage type k in the formula can be replaced. Replacing k with dc means battery energy storage, and replacing k with fl means flywheel energy storage.

[0196] The power characteristic coefficient of flywheel energy storage is an expression of the system frequency regulation response speed. According to the characteristics of flywheel energy storage, the pricing mechanism is mainly optimized through time scale and historical average frequency regulation performance.

[0197]

[0198] Where: fl is the flywheel relaxation factor; t fl is the flywheel frequency modulation response time; E flrate is the rated capacity of the flywheel energy storage; It is the maximum output of the flywheel at the current moment.

[0199] Based on the power characteristic coefficient, the optimized compensation price for frequency regulation mileage at any time in the flywheel energy storage frequency regulation auxiliary service market is:

[0200]

[0201] Where: The price for compensation of frequency adjustment mileage after correction; This is the price for compensation of frequency adjustment mileage before correction.

[0202] The capacity characteristic coefficient of battery energy storage is an expression of the system's frequency regulation response capacity, reflecting the impact of changes in the capacity of battery energy storage participating in frequency regulation demand on the frequency regulation price in the frequency regulation ancillary service market.

[0203]

[0204] Where: dc is the battery relaxation factor; t dc The frequency modulation response time of the battery; The maximum output of the battery at the current moment.

[0205] Based on the capacity relaxation coefficient, the frequency regulation optimization clearing price at any time in the battery energy storage frequency regulation auxiliary service market is:

[0206]

[0207] Where: The price for compensation of frequency regulation capacity after correction; It is the frequency regulation capacity compensation price before correction.

[0208] Secondly, the frequency modulation partition control layer is designed;

[0209] The frequency control center needs to follow the following principles during the frequency modulation signal distribution process: 1) The output of the coordinated system should minimize the deviation from the AGC signal; 2) The flywheel energy storage can be frequently switched between charge and discharge states; 3) The battery should not be frequently switched between charge and discharge states.

[0210] It is possible to achieve hybrid energy storage participating in frequency regulation while restoring SOC through electric energy charging and discharging. Specifically: ① When the flywheel energy storage is sufficient to meet the frequency regulation demand, the control strategy takes improving battery life as the main goal, and only uses the flywheel for frequency regulation output, so that it can give full play to the advantages of power-type energy storage and quickly meet the frequency regulation demand, while the battery energy storage participates in the electric energy market according to the optimal life assessment model of this article to obtain electric energy benefits. ② When the remaining frequency regulation capacity of the flywheel is insufficient, the control strategy takes participating in frequency regulation to ensure the frequency safety of the power grid as the main goal, and is limited by the dynamic balancing strategy of each energy storage SOC and the frequency regulation capacity of the hybrid energy storage. The battery energy storage is forced to participate in some small interference fluctuations, extending the overall frequency regulation capability of the hybrid energy storage.

[0211] Combination Figure 1 With the proposed underlying control strategy, the expressions of hybrid energy storage frequency regulation output and battery energy storage new energy dispatch output are as follows:

[0212] They are 0-1 variables for hybrid energy storage charging and discharging, and the relationship between them is:

[0213]

[0214] It is stipulated that at the same time, the main goal of controlling battery energy storage to ensure the safety of grid frequency is that battery energy storage can only work in the charging state or the discharging state.

[0215] The output of battery storage at time t is:

[0216]

[0217] Where: P b,t Total output for battery storage; The charging and discharging power of the battery involved in scheduling; It is the charging and discharging power of the battery participating in frequency modulation.

[0218] The battery energy storage response to the new energy dispatch power at time t is:

[0219]

[0220] Where: Dispatching power for battery energy storage.

[0221] The total power of hybrid energy storage participating in new energy dispatch and frequency regulation at time t is:

[0222]

[0223] Where: P t W It is the total output of hybrid energy storage; It is the charging and discharging power of the flywheel involved in scheduling.

[0224] Step 3: construct a hybrid energy storage transaction decision model;

[0225] The first step is to construct the objective function that maximizes the net benefit of frequency modulation, which is:

[0226]

[0227] Where: is the frequency modulation benefit at the current moment; C t neg is the power revenue at the current moment; C cost,t is the total cost at the current moment.

[0228] The total cost in the objective function is specifically: the total cost is composed of the frequency regulation capacity cost of energy storage and the frequency regulation mileage cost of energy storage:

[0229]

[0230] Where: The cost of frequency regulation capacity for hybrid energy storage; The mileage cost of hybrid energy storage frequency regulation.

[0231] The frequency regulation capacity cost of energy storage includes the opportunity cost caused by the energy storage participating in the frequency regulation auxiliary service at time t instead of participating in the electric energy market and the initial investment cost of the energy storage, which is not taken into account under joint clearing.

[0232]

[0233] Where: Regulating opportunity costs for the market; is the initial investment cost of hybrid energy storage.

[0234] The initial investment cost of hybrid energy storage consists of the initial investment costs of flywheel energy storage and battery energy storage:

[0235]

[0236] Where: Initial investment cost for battery energy storage; is the initial investment cost of flywheel energy storage; c cap is the unit capacity cost of battery energy storage; s is the number of dispatches, and the time scale is seconds; r k is the discount rate of energy storage; T k,float is the floating charge life of energy storage; cpcs is the flywheel unit power cost; P fl,rate is the flywheel rated power; c fess is the cost of a single flywheel device; c p is the unit power operation and maintenance cost of the flywheel; c e The operation and maintenance cost per unit capacity of the flywheel is almost 0.

[0237] The mileage cost of energy storage frequency regulation includes the energy loss cost caused by continuous charging and discharging of energy storage and the cycle life loss cost caused by the depth of energy storage discharge.

[0238]

[0239] Where: The cost of energy loss caused by charging and discharging; The cost of battery energy storage cycle life is reduced.

[0240] The life depreciation cost of hybrid energy storage refers to the fact that during actual operation, battery energy storage is affected by its characteristics. Charging and discharging will reduce its life and generate life depreciation costs. At the same time, its long-term operation will also lead to replacement costs. The original cost is simplified by the depreciation cost of each unit of battery energy storage in each settlement cycle, including the life depreciation of participating in the electric energy market and the life depreciation of participating in the frequency regulation auxiliary service market. During its life, the failure rate and capacity loss of flywheel energy storage are small, so no additional replacement cost and maintenance cost are required.

[0241]

[0242] Where: The lifetime loss cost of batteries in different markets; op is the impairment cost coefficient; η dc It is the battery charging and discharging efficiency.

[0243] The energy loss cost of hybrid energy storage charging and discharging is the energy loss cost caused by the charging and discharging efficiency not being 1 when the flywheel energy storage exchanges energy with the system. The expression is:

[0244]

[0245] Where: Energy loss costs of hybrid energy storage for charging and discharging; is the energy loss cost; η fl is the flywheel charge and discharge efficiency.

[0246] The benefits in the objective function are specifically: the frequency regulation benefits obtained by hybrid energy storage participating in frequency regulation and the electricity benefits of hybrid energy storage dispatching. The frequency regulation benefits of hybrid energy storage can be divided into the frequency regulation benefits obtained by flywheel participating in frequency regulation and the frequency regulation benefits obtained by battery participating in frequency regulation:

[0247]

[0248] In the formula, C cap for the net benefit of hybrid energy storage; is the frequency modulation benefit at the current moment; C t neg is the electricity revenue at the current moment; is the frequency modulation power at the current moment; To store energy in the flywheel and adjust the mileage; To store energy for batteries and increase mileage.

[0249] The electricity revenue from the dispatch of hybrid energy storage only includes the electricity revenue from the dispatch of battery energy storage:

[0250]

[0251] Where: The electricity revenue from dispatching battery energy storage; η dc The battery charging and discharging efficiency;

[0252] The second step is to design constraints. Since hybrid energy storage needs to participate in the auxiliary frequency regulation market and the electric energy market, and the life of battery energy storage is shorter than that of flywheel energy storage, the frequency regulation limit of flywheel energy storage is introduced to describe the trading boundary between the two markets and battery energy storage.

[0253] Compared with battery energy storage, flywheel energy storage has a higher reaction rate to meet the grid frequency safety. When only flywheel energy storage participates in frequency regulation, flywheel energy storage can meet the grid frequency fluctuation and maintain the grid frequency within the range allowed by the system. The maximum equivalent load fluctuation is called the flywheel energy storage frequency regulation limit, denoted as F N .

[0254] When the frequency regulation power cannot be met at the maximum frequency regulation capacity of flywheel energy storage alone, battery energy storage is required to participate in meeting the frequency regulation power shortage even when the battery energy storage life loss is large. From the definition of flywheel frequency regulation limit, it can be known that calculating the flywheel frequency regulation limit is to calculate the maximum equivalent load fluctuation that the flywheel energy storage can withstand at each moment.

[0255] F N =min(P fl,rate ,P fl,re ) (33);

[0256]

[0257] Where: P fl,re is the remaining frequency modulation power of the flywheel; SOC fl,t is the current SOC of the flywheel; SOC fl,maxis the maximum SOC state of the flywheel; SOC fl,min is the minimum SOC state of the flywheel; η fl is the flywheel charge and discharge efficiency.

[0258] From the design of the frequency regulation partition control layer, it can be seen that different objectives are used as constraints in different intervals: ① When the grid frequency fluctuation meets the set power-type energy storage frequency regulation, the main goal is to increase the life of the battery energy storage, including the frequency regulation constraints of the hybrid energy storage, the SOC state constraints of the hybrid energy storage, and the upward and downward frequency regulation constraints of the battery energy storage.

[0259] Battery energy storage bidding power constraints: At the current moment, the power of battery energy storage participating in the electric energy market and the frequency regulation auxiliary service market meets the maximum, minimum charging and discharging power and rated power constraints.

[0260]

[0261] Where: P dc,max is the remaining maximum frequency modulation power when the battery SOC limit is close to 0.9, P dc,min It is the remaining maximum frequency modulation power when the battery SOC limit is close to 0.1.

[0262] Battery energy storage capacity constraint: Set the optimal SOC limit capacity based on battery life assessment.

[0263]

[0264] Where: E dc,t is the battery capacity at the current moment; S dc_ The best upper limit SOC for battery life evaluation; S dc_ Evaluate the optimal lower limit SOC for battery life.

[0265] Battery energy storage cycle life constraint: The battery energy storage cycle life constraint is given by step 2.

[0266] ② When the grid frequency fluctuation exceeds the set flywheel energy storage frequency regulation limit, with the main goal of ensuring grid frequency safety, the hybrid energy storage power station participating in the frequency regulation auxiliary service market needs to consider the frequency regulation capacity limitations of flywheel energy storage and battery energy storage, as well as their charging and discharging capacity constraints.

[0267] Battery storage capacity constraints:

[0268]

[0269] Where: SOC dc,max , SOC dc,max It is the maximum and minimum SOC state of the battery.

[0270] ③ Hybrid energy storage only participates in the frequency regulation service market. When the grid frequency fluctuation exceeds the set hybrid energy storage frequency regulation limit, with the main goal of ensuring grid frequency safety, all hybrid energy storage is only used in the frequency regulation auxiliary service market, increasing the opportunity cost caused in the objective function.

[0271] Battery storage capacity constraints:

[0272]

[0273] ④Other constraints, specifically:

[0274] Frequency modulation power balance constraints:

[0275]

[0276] FM power constraints:

[0277]

[0278] SOC constraints:

[0279]

[0280] Due to the characteristics of battery energy storage life, frequent control of energy storage for charging and discharging switching is not conducive to reducing the attenuation of life. Therefore, this paper uses the operating duration as the switching charging and discharging constraint to improve the decision-making transformation of battery energy storage for potential future situations. The battery energy storage charging and discharging switching flexibility constraints are divided into the maximum number of charging and discharging cycles constraints and the charge and discharge duration constraints.

[0281] Constraints on the maximum number of charge and discharge cycles:

[0282]

[0283] In the formula: σ is the charge and discharge symbol; k is the charge and discharge time; is the change of discharge state; To change to a discharge state; The charging state changes; Change to charging state.

[0284] Frequency modulation charging and discharging operation duration constraints:

[0285] From the perspective of the energy storage element itself, the duration of its charge and discharge operation is affected by its capacity-power ratio and the current state of charge. However, when participating in frequency modulation operation, in order to avoid the impact of frequent switching on the life of energy storage, a strict charge and discharge duration constraint model is proposed. Its expression is:

[0286]

[0287] Where: Tc 、T d To limit the charging and discharging time; is the time adjustment factor; TC and TD are the duration of charge and discharge.

[0288] The third step is to construct the hybrid energy storage efficiency index. The hybrid energy storage efficiency index is mainly reflected in the frequency regulation performance, and the frequency regulation performance is evaluated by the AGC instructions that can be achieved by the thermal power unit frequency regulation assistance. The regulation performance assessment is mainly reflected in the comprehensive evaluation index of frequency regulation performance by considering the three factors of regulation rate, regulation accuracy and response time. The comprehensive evaluation index expression is as follows:

[0289] K P,i =K 1,i K 2,i K 3,i (44);

[0290] Where: K P,i To measure the degree of regulation performance in the i-th regulation process; K 1,i , K 2,i and K 3,i They are respectively the adjustment rate, accuracy and response time of the i-th adjustment of the system frequency modulation.

[0291] The frequency regulation performance evaluation of the AGC instructions that can be achieved by the thermal power unit frequency regulation assistance is carried out as follows:

[0292] ① Frequency modulation rate

[0293] The regulation rate refers to the rate at which the unit responds to the setpoint command, which can be divided into rising rate and falling rate. The calculation process of the j-th regulation rate assessment index of the i-th unit is as follows:

[0294] The actual adjustment rate calculation formula is as follows:

[0295]

[0296] Where: v i,j is the jth regulation rate of unit i (MW / min), P Ei,j is the output (MW) at the end of the response process, P Si,j is the output (MW) at the start of operation, T Ei,j It's time to end, T Si,j It's time to start, P di,j is the critical power of the start-stop grinding mill of the jth adjustment (MW), T di,j It is the actual time consumed by adjusting the start and stop of the grinding mill for the jth time.

[0297] When the unit does not meet the typical AGC set point control process (fails to enter the target dead zone), the regulation rate is the unit output at the end of the instruction minus the active change in the output at the time of crossing the dead zone divided by the required time.

[0298] The calculation formula of the regulation rate regulation index is:

[0299]

[0300] If K 1 i,j If the calculated value is less than 0.1, take 0.1.

[0301] Where: v N,i is the standard regulation rate of unit i, in MW / minute. If the unit enters the deep regulation condition below 50% of the rated output, the AGC regulation rate is required to be 80% of the conventional regulation.

[0302] ②Adjustment accuracy

[0303] The regulation accuracy refers to the difference between the actual output and the set point output after the unit response is stable. The absolute value of the difference between the actual output and the command is integrated, and then the integral is divided by the integration time to obtain the regulation deviation for that period.

[0304]

[0305] Where: P i,j (t) is the actual output during the period, P i,j Get the set point command value for this period, T Ei,j is the end of the time period, T Si,j If the unit fails to enter the target dead zone, the adjustment accuracy is the minimum value of the deviation between the actual output and the target output in the time period from the time when the unit steps out of the dead zone in the same direction to the time when the instruction ends.

[0306]

[0307] Where: The allowable deviation of regulation is 1% of the rated active power of the unit. When the unit enters the deep regulation condition below 50% of the rated output, the AGC regulation accuracy requirement is 125% of the conventional regulation.

[0308] ③Response time

[0309] Response time refers to the time it takes for the unit to reliably step out of the frequency regulation dead zone consistent with the regulation direction at the original output point after the EMS system issues a command.

[0310]

[0311] The AGC response time of thermal power units should be less than 1 minute. When the unit enters the deep adjustment condition with the rated output below 50%, the AGC response time is 125% of that of conventional units.

[0312] The above and If the calculated value is less than 0.1, it is taken as 0.1 and the evaluation index is used. Calculation of and If one of the calculated values ​​is greater than 2, then none of the three calculated values ​​will be evaluated. calculation; assessment and If the calculated values ​​are all within the range of [0.1, 2], the evaluation index is Calculation.

[0313] The process described in step 3 is shown in Figure 3 ;

[0314] The fourth step is to use the control method of the present invention to simulate and analyze a specific example:

[0315] The rated capacity of the unit is set to 330MW, the battery energy storage system parameters are 5MW / 2.5MWh, the charging and discharging efficiency is 0.9, the flywheel energy storage system parameters are 5MW / 0.5MWh, the charging and discharging efficiency is 0.85, and the energy storage SOC is 0.5. The simulation analysis is carried out in the MATLAB / Simulink simulation environment.

[0316] In order to verify the advantages of the solution of the present invention, Model 1 is set as the response model of the present invention that gives economy and SOC recovery; Model 2 only considers the frequency modulation economy but does not consider various constraints on the battery energy storage life. Figure 4 It can be seen that model 1 follows the AGC instruction more effectively and has a better following degree. The frequency deviation of model 1 is better than that of model 2, and the practicality of model 1 is more obvious. Figure 5 It can be seen that the flywheel output of model 1 is more obvious, which reflects the high power and long life of flywheel energy storage, and solves the problem of frequent charging and discharging of battery energy storage and shortening its life. Figure 6 It can be seen that compared with the frequent fluctuations of flywheel energy storage, the life loss of battery energy storage is effectively reduced, reflecting the long life and long cycle life of flywheel energy storage and the large capacity of battery energy storage. Figure 7 It can be seen that compared with model 2, model 1 has more concentrated fluctuations and is more gentle in life assessment, which is more conducive to long-term frequency regulation and protection of battery energy storage from exceeding the SOC limit. The present invention designs four schemes: scheme 1 has no energy storage, scheme 2 and scheme 3 are single battery energy storage and single flywheel energy storage frequency regulation schemes with the same total configuration power, respectively, and scheme 4 is a hybrid energy storage scheme. Figure 8It can be seen that Scheme 4 has the best performance in terms of frequency regulation performance improvement. Compared with the scheme containing only flywheel and battery, the hybrid energy storage scheme has a significant effect in improving the frequency regulation performance.

[0317] The embodiments of the present invention are not exhaustive and do not constitute a limitation on the protection scope of the claims. Based on the inspiration gained from the embodiments of the present invention, those skilled in the art can think of other substantially equivalent alternatives without creative work, all of which are within the protection scope of the present invention.

Claims

1. A method for controlling the life economy of hybrid energy storage and frequency modulation limit partition, characterized by: The method comprises the following steps, and the following steps are performed in sequence: Step 1: Establish a hybrid energy storage combined frequency regulation system and obtain hybrid energy storage output, battery output and flywheel output; Step 2: Formulate a double-layer optimization allocation model for hybrid energy storage to assist thermal power unit frequency regulation, wherein the double-layer optimization allocation model includes a hybrid energy storage upper-layer scheduling model and a hybrid energy storage bottom-layer control strategy; 1) The hybrid energy storage upper-layer scheduling model performs real-time state optimization of the hybrid energy storage, including: ① Establish a battery life loss model based on real-time energy storage state of charge (SOC) and equivalent life cycle to evaluate the optimal life of battery energy storage; ②Provide SOC dynamic balance quotation; ③ Characterize the hybrid energy storage performance; 2) According to the formulated hybrid energy storage underlying control strategy, combined with AGC instructions, thermal power unit output and real-time optimization status of hybrid energy storage, frequency modulation partition control is performed to obtain hybrid energy storage frequency modulation output and battery energy storage new energy dispatching output; Step 3: Establish a hybrid energy storage transaction decision model, and obtain a hybrid energy storage operation plan suitable for all scenarios by solving the objective function of the model; 1) The objective function is: Where: is the frequency modulation benefit at the current moment; C t neg is the power revenue at the current moment; C cost,t is the total cost at the current moment; in, Where: The cost of frequency regulation capacity for hybrid energy storage; The mileage cost of frequency regulation for hybrid energy storage; Where: The capacity and mileage subsidy income obtained by flywheel energy storage participating in frequency regulation during the frequency regulation period. The capacity and mileage subsidy income obtained by battery energy storage participating in frequency regulation during the frequency regulation cycle. is the frequency regulation capacity compensation price before correction, is the flywheel frequency modulation power at the current moment, The revised frequency adjustment mileage compensation price, To store energy in the flywheel and adjust the mileage; is the revised frequency regulation capacity compensation price, is the battery frequency modulation power at the current moment, The price of compensation for frequency adjustment mileage before correction. Frequency modulation for battery storage; Where: The electricity revenue from dispatching battery energy storage; η dc is the battery charging and discharging efficiency; ce is the on-grid electricity price, Charging power for the battery, is the battery discharge power; 2) Establish constraints; ①Battery energy storage aims to increase lifespan; ②Battery energy storage aims to ensure the safety of grid frequency; ③ Hybrid energy storage only participates in the frequency regulation service market; ④Other constraints; Step 4: Establish a hybrid energy storage efficiency index as an evaluation index. The hybrid energy storage efficiency index is mainly reflected in the frequency regulation performance. The frequency regulation performance is evaluated by evaluating the AGC instructions that can be achieved by the frequency regulation assistance of the thermal power unit.

2. According to claim 1, a method for controlling the zoning of hybrid energy storage based on the life economy and frequency modulation limit is characterized by: The mixed energy storage output in step 1 is specifically: The difference between the AGC command and the output of the thermal power unit is used as the AGC command of the hybrid energy storage in this area, then: Where: is the hybrid energy storage frequency modulation power; P G,t Frequency modulation power for thermal power units; is the AGC instruction; P t en Trading power for energy storage; It is the remaining power of hybrid energy storage at the current moment.

3. The method for controlling the hybrid energy storage life economy and frequency modulation limit partition according to claim 1 is characterized by: The battery output and flywheel output in step 1 are specifically: The frequency modulation includes flywheel frequency modulation output and battery frequency modulation output, as well as the battery charging and discharging energy trading to increase the battery life. Where: The frequency modulation power of the flywheel; is the battery frequency modulation power, P is the charge and discharge power of the battery energy storage under SOC recovery. dc,rate is the rated power of the battery.

4. The method for controlling the hybrid energy storage life economy and frequency modulation limit partition according to claim 1 is characterized by: In step 2, the optimal life of battery energy storage is evaluated, specifically: The throughput method is used to calculate the battery life, and a life evaluation model for battery energy storage is built. The maximum number of charge and discharge cycles that can be achieved at the charge and discharge depth x is fitted into a polynomial. The relationship of the life evaluation model for battery energy storage is as follows: N x =-12894x 5 +37860x 4 -42699x 3 +23528x 2 -6785.4x+12446.2; Where: N x is the number of cycle life of battery energy storage when the depth of charge and discharge is x; Calculate the maximum power throughput corresponding to the depth of charge and discharge of the battery energy storage. According to the maximum number of charge and discharge cycles under x and the power value that can be throughput in one charge and discharge cycle, calculate and obtain the total power that the battery can throughput when running at x during its life cycle: Where: E x is the total amount of electricity that the battery energy storage can handle when operating at x during its life cycle; E1 is the amount of electricity that the battery energy storage can handle when operating at x in one charge and discharge cycle; E dcrate The rated capacity of the battery energy storage; By quantifying the relationship between the depth of discharge, discharge range and equivalent cycle life, a battery energy storage life loss model based on real-time SOC state and equivalent life cycle number is constructed: Where: N x N is the number of energy storage life cycles at the current charge and discharge depth, max is the number of energy storage life cycles at the maximum charge and discharge depth; x ref is the equivalent life cycle number; SOC dc,t The current SOC of the battery energy storage, SOC dc,ref is the equivalent SOC state, μ1 and μ2 are constants provided by the battery manufacturer; Establish the equivalent life cycle number of battery energy storage at different discharge depths (DOD) in each SOC range: Where: n eq is the number of unit equivalent life cycles; Through the battery energy storage life loss model, the relationship between SOC and unit transfer energy is obtained: Where: e SOC,t Transfer energy for the current SOC state unit; k p is a constant, and is obtained by fitting the relationship between the number of energy storage cycles and the depth of discharge using the actual operating data provided by the battery manufacturer.

5. The method for controlling the hybrid energy storage life economy and frequency modulation limit partition according to claim 1 is characterized by: The step 2 is to carry out SOC dynamic balance quotation, specifically: The energy storage income is limited by the SOC dynamic equilibrium quotation coefficient to achieve the effect of constraining the frequency modulation output. To ensure the high power of flywheel energy storage, the non-limit range of flywheel energy storage is set to 0.1-0.

9. To ensure the high capacity of battery energy storage, the non-limit range of battery energy storage is set to 0.2-0.

8. Based on the evaluation of the optimal life of battery energy storage, the optimal working state of energy storage SOC is set to 0.4-0.6; The SOC dynamic balance quotation is based on the real-time energy storage SOC dynamic response to control energy storage, which is: When charging: In discharge state: Where: SOC k,low , SOC k,high is the minimum and maximum thresholds under the optimal state of SOC, is the adjustment factor during charging, SOC k,t is the SOC of energy storage at time t, is the adjustment factor during discharge.

6. The method for controlling the hybrid energy storage life economy and frequency modulation limit partition according to claim 1 is characterized by: The hybrid energy storage performance is characterized in step 2, specifically: Frequency regulation performance is introduced to characterize the different frequency regulation characteristics of hybrid energy storage. The power characteristic coefficient is used to quantify the impact of the frequency regulation mileage of the frequency regulation resources during the frequency regulation process on the flywheel frequency regulation benefits. The capacity characteristic coefficient is used to characterize the impact of the change in the frequency regulation demand capacity of the frequency regulation resources during the frequency regulation process on the battery frequency regulation benefits. The frequency regulation performance coefficient of flywheel energy storage and battery energy storage is established based on the historical frequency regulation performance index, as shown in the following formula: Where: Kp is the frequency modulation factor under the historical frequency modulation performance index; k Kp is the historical frequency regulation performance index of each energy storage; sat Kp is the historical frequency modulation performance saturation index; min It is the minimum index of historical frequency modulation performance; In the above formula, k represents the energy storage type. If k is replaced by dc, the above formula is the frequency regulation performance coefficient of battery energy storage. If k is replaced by fl, the above formula is the frequency regulation performance coefficient of flywheel energy storage. The power characteristic coefficient of flywheel energy storage is: Where: fl is the flywheel relaxation factor; t fl is the flywheel frequency modulation response time; E flrate is the rated capacity of the flywheel energy storage; is the maximum output of the flywheel at the current moment, Δt is the time interval; Based on the power characteristic coefficient, the optimized compensation price for frequency regulation mileage at any time in the flywheel energy storage frequency regulation auxiliary service market is obtained as follows: Where: The price for compensation of frequency adjustment mileage after correction; The price for compensation of frequency adjustment mileage before correction; The capacity characteristic coefficient of battery energy storage is: Where: dc is the battery relaxation factor; t dc The frequency modulation response time of the battery; The maximum output of the battery at the current moment; The maximum output of the battery at the current moment; Based on the capacity characteristic coefficient, the frequency regulation optimization clearing price at any time in the battery energy storage frequency regulation auxiliary service market is obtained as follows: Where: The price for compensation of frequency regulation capacity after correction; It is the price for frequency regulation capacity compensation before correction.

7. The method for controlling the hybrid energy storage life economy and frequency modulation limit partition according to claim 1 is characterized by: The underlying control strategy of the hybrid energy storage in step 2 is specifically as follows: ① If the flywheel energy storage is sufficient to meet the frequency regulation demand, the control strategy aims to improve the battery life. The flywheel is used alone for frequency regulation output, so that it can give full play to the advantages of power-type energy storage and meet the frequency regulation demand. The battery energy storage participates in the electric energy market based on the battery energy storage life assessment model to obtain electric energy benefits. ② If the remaining frequency regulation capacity of the flywheel is insufficient, the control strategy aims to participate in frequency regulation to ensure the frequency safety of the power grid, with the dynamic balance of each energy storage SOC and the frequency regulation capacity of the hybrid energy storage as limitations. The battery energy storage is forced to participate in some small interference fluctuations, extending the overall frequency regulation capacity of the hybrid energy storage.

8. The method for controlling the hybrid energy storage life economy and frequency modulation limit partition according to claim 1 is characterized by: The expressions of the hybrid energy storage frequency modulation output and the battery energy storage new energy dispatching output in step 2 are as follows: They are 0-1 variables for hybrid energy storage charging and discharging, and the relationship between them is: It is stipulated that battery energy storage can only work in charging state or discharging state at the same time; The output of battery storage at time t is: Where: P b,t Total output for battery storage; The charging and discharging power of the battery involved in scheduling; The charging and discharging power of the battery participating in frequency modulation; A 0-1 variable to charge the battery; A 0-1 variable for battery discharge; The battery energy storage response to the new energy dispatch power at time t is: Where: dispatching power for battery energy storage; The total power of hybrid energy storage participating in new energy dispatch and frequency regulation at time t is: Where: P t W It is the total output of hybrid energy storage; The charge and discharge power of the flywheel involved in scheduling; is a 0-1 variable for flywheel discharge; A 0-1 variable that charges the flywheel.

9. The method for controlling the hybrid energy storage life economy and frequency modulation limit partition according to claim 1 is characterized by: The constraints in step 3 are specifically: ① Constraints on battery energy storage with the goal of increasing lifespan, specifically: Battery energy storage bidding power constraints: At the current moment, the power of battery energy storage participating in the electric energy market and frequency regulation auxiliary service market meets the maximum, minimum charging and discharging power and rated power constraints: Where: P dc,max is the remaining maximum frequency modulation power when the battery SOC limit is close to 0.9, P dc,min It is the remaining maximum frequency modulation power when the battery SOC limit is close to 0.1, is the battery discharge power, is the frequency modulation power when the battery is discharged, P dc,rate is the battery rated power, Charging power for the battery, FM power when charging the battery; Battery storage capacity constraints: Based on the battery life assessment, the optimal SOC limit capacity is set: Where: E dc,t is the battery capacity at the current moment; S dc_ Evaluate the optimal upper limit SOC for battery life; The optimal lower limit SOC for battery life evaluation; η dc The battery charging and discharging efficiency; Battery energy storage cycle life constraint: obtained through the battery energy storage life loss model of real-time SOC state and equivalent life cycle number; ② The constraints of battery energy storage to ensure grid frequency safety are as follows: Battery storage capacity constraints: Where: SOC dc,max , SOC dc,max The maximum and minimum SOC states of the battery; ③ Hybrid energy storage only participates in the frequency regulation service market, specifically: Battery storage capacity constraints: Where: E i,t is the battery capacity at the current moment, SOC i,max is the maximum SOC value, SOC i,min is the minimum SOC value, E i,rate is the rated capacity, is the frequency modulation power during charging at the current moment, η i is the charge and discharge efficiency; ④Other constraints, specifically: Frequency modulation power balance constraints: FM power constraints: Where: is the energy storage frequency modulation power during discharge at the current moment, The energy storage frequency modulation power during charging at the current moment, is the minimum frequency modulation power of energy storage during charging at the current moment, P k,rate is the energy storage rated power, The maximum frequency modulation power of energy storage during charging at the current moment; SOC constraints: Where: SOC k,min is the minimum energy storage SOC, SOC k,max is the maximum energy storage SOC, η k For energy storage charging and discharging efficiency, is the energy storage discharge power at the current moment, The energy storage charging power at the current moment; Due to the characteristics of battery energy storage life, the operation duration is used as the switching charge and discharge constraint. The battery energy storage charge and discharge switching flexibility constraint is divided into the maximum charge and discharge cycle constraint and the charge and discharge duration constraint. The maximum number of charge and discharge cycles is constrained to: In the formula: σ is the charge and discharge symbol; k is the charge and discharge time; is the change of discharge state; To change to a discharge state; The charging state changes; is the change to charging state; N0 is the maximum number of charge and discharge cycles; Frequency modulation charging and discharging operation duration constraints: Where: T c , T d To limit the charging and discharging time; is the time adjustment factor; TC and TD are the duration of charge and discharge; They are respectively changed into charging state and changed into discharging state; They are respectively the duration of charging and the duration of discharging.

10. The method for controlling the zoning of hybrid energy storage based on the life economy and frequency modulation limit according to claim 1 is characterized by: The regulation performance in step 4 includes three factors: regulation rate, regulation accuracy and response time; The evaluation index expression is as follows: Where: It is an evaluation index to measure the regulation performance of the i-th unit during the j-th regulation process; and are the adjustment rate, accuracy and response time of the jth adjustment of the i-th unit respectively; The frequency regulation performance evaluation of the AGC instructions that can be achieved by the thermal power unit frequency regulation assistance is carried out as follows: ① Frequency modulation rate The regulation rate refers to the rate at which the unit responds to the setpoint command, which is divided into rising rate and falling rate. The calculation process of the jth regulation rate of the i-th unit is as follows: The actual adjustment rate calculation formula is as follows: Where: v i,j is the jth actual regulation rate of the i-th unit, in MW / minute; P Ei,j is the output at the end of the response process, in MW; P Si,j is the output when it starts to move, in MW; T Ei,j It's time to end, T Si,j It's time to start, P di,j is the critical power of the start-stop grinding mill of the jth adjustment, in MW; T di,j is the actual time consumed by the jth adjustment of starting and stopping the grinding mill; If the unit does not meet the typical AGC set point control process, that is, the unit fails to enter the target dead zone, the regulation rate is the unit output at the end of the instruction minus the active change of the output at the time of crossing the dead zone divided by the required time; The calculation formula of the regulation rate regulation index is: Where: v N,i is the standard regulation rate of unit i, in MW / min; ②Adjustment accuracy The regulation accuracy refers to the difference between the actual output and the set point output after the unit response is stable. The method of obtaining it is: integrate the absolute value of the difference between the actual output and the command, and then divide the integral by the integration time to obtain the regulation deviation for the period. The formula is as follows: Where: P i,j (t) is the actual output during the period, P i,j Get the set point command value for this period, T Ei,j is the end of the time period, T Si,j is the starting point of the time period; If the unit fails to enter the target dead zone, the regulation accuracy is the minimum value of the deviation between the actual output and the target output during the period from the time when the unit steps out of the dead zone in the same direction to the time when the command ends: Where: The allowable deviation of regulation is 1% of the rated active power of the unit; ③Response time Response time refers to the time it takes for the unit to reliably step out of the frequency regulation dead zone consistent with the regulation direction at the original output point after the EMS system issues a command. The formula is as follows: Where: is the time when the i-th unit leaves the initial regulation dead zone during the j-th regulation process, T1 is the time when the regulation dead zone is left, T0 is the time when the unit starts to output, is the time when the i-th unit leaves the last adjustment dead zone during the j-th adjustment process, T6 is the time when it leaves the grinding stop point, T5 is the time when the AGC control program issues a new set point command to the unit, t i,j is the response time of the jth AGC unit of the i-th unit; the standard AGC response time of thermal power units is less than 1min; The above and If the calculated value is less than 0.1, it is taken as 0.1 and the evaluation index is used. Calculation of and If one of the calculated values ​​is greater than 2, then none of the three calculated values ​​will be evaluated. calculation; assessment and If the calculated values ​​are all within the range of [0.1, 2], the evaluation index is Calculation.

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