Fire storage combined frequency modulation system optimal configuration method

Abstract

The invention discloses an optimal configuration method for a fire-storage combined frequency modulation system, which comprises the following steps of: firstly, establishing a total cost loss model of the fire-storage combined frequency modulation system, and subtracting a frequency modulation compensation income model of a power grid side from the total cost loss model to obtain a total economic benefit model of the fire-storage combined frequency modulation system; secondly, on the basis of a thermal power generating unit day-ahead load curve issued by a power grid side, an artificial bee colony optimization algorithm is adopted to solve the optimal output of the thermal power generating unit and an energy storage battery, and a trend chart of the energy storage charge state is obtained; and finally, applying the optimized output value to a fire storage combined frequency modulation simulation response process, and carrying out pre-charge state configuration adjustment on the stored energy based on the trend chart. Compared with a thermal power and energy storage combined frequency modulation strategy which only considers frequency modulation income, the total economic benefit of the thermal power and energy storage combined frequency modulation system under the method during frequency modulation is improved, and the availability rate of the energy storage battery is further improved.

Description

Technical Field

[0001] The invention relates to an optimization configuration technology for a combined fire-storage frequency regulation system, and belongs to the technical field of load optimization distribution strategy for a combined fire-storage frequency regulation system. Background Art

[0002] The current load optimization allocation method for combined thermal power generation and energy storage frequency regulation mainly focuses on maximizing the frequency regulation compensation benefits of the power grid, lacks detailed consideration of the cost losses of thermal power units and energy storage batteries in the process of combined thermal power generation and energy storage frequency regulation, and does not achieve the theoretical optimality of the total economic benefits of the combined thermal power generation and energy storage frequency regulation system. In the actual frequency regulation command response process, thermal power units often respond to frequency regulation commands quickly at their maximum achievable regulation rate, which will lead to increased frequency regulation costs in various aspects of thermal power units, such as increased total coal consumption and increased environmental protection payment costs. In addition, energy storage only makes up for the power difference, and frequent charging and discharging of capacity leads to overcharging or over-discharging of batteries, lacking a more goal-oriented state of charge adjustment method. Summary of the invention

[0003] Technical problem: The present invention aims to solve the technical problems that the existing fire-storage joint frequency regulation instruction response method does not fully consider the cost loss of fire-storage joint frequency regulation and the lack of a clearer pre-charge and discharge guidance reference for the adjustment of the energy storage charge state, and proposes a fire-storage joint frequency regulation system optimization configuration method. Under the application of this method, when the fire-storage joint frequency regulation is applied, the coordination of its power output not only considers the frequency regulation compensation income but also the cost loss of the fire-storage joint frequency regulation. In addition, the charge state of the energy storage will be far away from the upper and lower limits of 0.2 or 0.8, and the availability will be further improved.

[0004] Technical solution: A method for optimizing the configuration of a combined frequency modulation system of a thermal energy storage system of the present invention comprises the following steps:

[0005] S1: A mathematical model of total cost loss of the thermal-storage combined frequency regulation system was established;

[0006] S2: The total cost loss mathematical model minus the power grid frequency regulation compensation benefit model is used to obtain the total economic benefit model of the thermal-storage combined frequency regulation system;

[0007] S3: Select the load curve of the thermal power unit issued by the power grid in advance as the equality constraint condition to be satisfied for optimization. At the same time, perform optimization calculation under the inequality constraint condition that meets the basic upper and lower power limits of the thermal power unit and the energy storage battery to obtain the thermal storage optimized output value.

[0008] S4: Using artificial bee colony optimization algorithm to calculate the optimal output of thermal power units and energy storage and obtain the trend diagram of energy storage charge state;

[0009] S5: Apply the optimized output value of the thermal storage obtained by the optimization calculation to the thermal storage combined frequency regulation and load changing process so that the total economic benefit of the thermal storage combined frequency regulation system during frequency regulation tends to the theoretical optimum;

[0010] S6: According to the obtained energy storage charge state change trend diagram, during the frequency modulation waiting instruction process, the energy storage battery charge state is pre-adjusted by using the fluctuating power of the thermal power unit, so that the energy storage battery charge state, i.e., the SOC value, is far away from the upper and lower limit requirements of 0.2 or 0.8, thereby improving its availability index.

[0011] The step S1 comprises: respectively modeling the cost losses of the thermal power unit and the energy storage battery in the frequency regulation process; firstly, the frequency regulation cost modeling of the thermal power unit takes into account the frequency regulation coal consumption cost modeling and the environmental protection payment cost modeling of the thermal power unit, and the frequency regulation coal consumption cost modeling of the thermal power unit is subdivided into steady-state coal consumption modeling and transient coal consumption modeling, and the environmental protection payment cost modeling of the thermal power unit is the environmental payment cost modeling caused by the unit's pollutant emissions; secondly, the cost loss modeling of the energy storage battery in the frequency regulation process is the life depreciation cost modeling caused by its discharge; finally, the frequency regulation coal consumption cost model and the environmental protection payment cost model of the thermal power unit are added to the life depreciation cost model of the energy storage battery in the frequency regulation process to obtain the total cost loss mathematical model of the thermal-storage combined frequency regulation system.

[0012] The total cost loss mathematical model of the fire-storage combined frequency regulation system is:

[0013] C zong =C mei +C pai +C batlife

[0014] Where: C zong is the total loss cost of the combined frequency regulation process of thermal energy storage; C mei is the total coal consumption cost of the combined frequency regulation process of thermal power plant and fuel storage; C pai Environmental protection payment cost for the combined frequency regulation process of thermal energy storage; C batlife The battery life loss cost for the thermal-storage combined frequency regulation process;

[0015] The coal consumption cost fitting model of thermal power units is as follows:

[0016]

[0017] Where: C mei is the coal consumption cost per hour; V e Adjust the load rate for thermal power units; C price is the real-time coal price, m wen is the coal consumption of thermal power units in steady state, P is the unit load, a1, a2, a3, and a4 are 0.003, 0.013, 0.001, and -0.176 respectively;

[0018] The environmental protection payment cost model is as follows:

[0019]

[0020] Where: λ is the adjustment coefficient; P NOx , P SO2 are the emission values ​​of NOx and SO2 respectively; N1 and N2 are the equivalent values ​​of NOx and SO2 emission values ​​respectively;

[0021] The life-cycle depreciation cost model of energy storage is as follows:

[0022]

[0023] C ini is the initial investment cost of the battery; d is the single discharge ampere-hour of each load change process; the total effective discharge capacity during the life cycle can be expressed by the following formula:

[0024] Γ R =L R D R C R

[0025] Where: L R is the rated cycle life of the battery; D R is the rated discharge depth; C R is the rated capacity of the battery.

[0026] The steady-state coal consumption modeling involves the amount of coal consumed per unit of power generation when the thermal power unit is at a certain fixed power output. The fitting and regression analysis of coal consumption data of various types of main units are performed to obtain the change model of power and coal consumption of thermal power units; its basic mathematical model is as follows:

[0027]

[0028] Where: m wen is the coal consumption of thermal power unit in steady state, P is the unit load; m0 is the reference coal consumption, P0 is the reference load; a=0.798; b=0.988; u0=0.0035; t=0.245; β0=-0.0348.

[0029] In step S2, the total cost loss mathematical model C zong Subtract the power grid frequency regulation compensation benefit model Gain to obtain the total economic benefit model OBJ of the thermal-storage combined frequency regulation system.

[0030] OBJ=C zong -Gain

[0031] The grid frequency regulation compensation revenue model Gain is:

[0032] Gain=KDQ

[0033] Among them: K is the comprehensive performance index of frequency regulation, D is the frequency regulation mileage, which generally refers to the absolute value of the difference between the actual output and the initial output after the unit responds to the command, and Q is the frequency regulation compensation price.

[0034] In step S3, the load curve of the thermal power unit sent in advance by the power grid is selected as the equality constraint condition to be satisfied for optimization, and the optimization calculation is performed under the inequality constraint condition that meets the basic upper and lower limits of the power of the thermal power unit and the energy storage battery. The day-ahead load curve of the thermal power unit is the load forecast curve for the next day sent in advance by the power grid side. The sum of the output of the thermal power unit and the energy storage battery should take the command value as the adjustment target to meet the basic command power requirement, and obtain the thermal storage optimized output value:

[0035]

[0036] The above formula shows that the optimized output value of the thermal power unit should be obtained between its minimum allowable value and maximum allowable value;

[0037]

[0038] The above formula shows that the optimized output value of the energy storage battery should be obtained between its minimum allowable value and maximum allowable value.

[0039] In step S4, the artificial bee colony optimization algorithm is used to calculate the optimal output of the thermal power unit and the energy storage and obtain the trend diagram of the change of the energy storage charge state; the algorithm logic sequence of the artificial bee colony optimization algorithm under the present method model is as follows: the first step is to initialize, input the basic parameters of the thermal storage equipment such as power limit, then input the parameters of the artificial bee colony optimization algorithm such as determining the number of bees to be 200, the maximum number of iterations to be 300, and generate the initial random solution x i , i = 1, 2, ..., 100; in the second step, the employed bees generate new random solutions s in the neighborhood of the initial random solution according to the formula ij , calculate and compare the advantages and disadvantages of the new solution and the initial solution, and keep the solution with better fitness;

[0040] s ij =x ij +β ij (x ij -x kj )

[0041] Where: k∈{1,2,...,100},k≠i; j∈{1,2}; β ij A random number between -1 and 1;

[0042] In the third step, the employed bee shares the solution information with the follower bee and calculates the probability value of each solution according to the following formula:

[0043]

[0044] Among them: fit i is the fitness value corresponding to each solution, that is, the quality of the solution.

[0045] Then, based on the roulette method, a random number is generated between -1 and 1. If the random number is less than the probability value of the solution, the current optimal solution is retained according to the steps in the second step.

[0046] After the follower bee search is completed in the fourth step, check whether there is a local optimal solution, that is, whether there is a solution that has not been updated for more than the maximum number of unupdated times M. If so, the local optimal solution is discarded and a new solution is generated according to the following formula:

[0047] x ij =x mini +α(x maxj -x minj )

[0048] Among them: α is a random number between 0 and 1; x mini 、x maxj 、x minj is the minimum and maximum value of the solution of the corresponding dimension; then repeat the above steps;

[0049] The fifth step is to check whether the maximum number of iterations 300 has been reached. If so, the optimal solution can be output.

[0050] Finally, the optimized output value of the thermal-storage combined frequency regulation system is obtained, and further the changing trend diagram of the energy storage charge state is obtained.

[0051] In the step S5, the optimized output value of the thermal storage obtained by the optimization calculation is applied to the thermal storage combined frequency regulation and load change process so that the total economic benefit of the thermal storage combined frequency regulation system during frequency regulation tends to be theoretically optimal; when applying it, it is necessary to first compare the load command forecast value issued in advance by the power grid side with the actual load command value, that is, when the deviation between the day-ahead predicted load command and the actual load command value is less than a certain allowable value L, the thermal storage optimal output value calculated in advance is applied to the load change process with a smaller load command deviation, which is equivalent to performing optimization calculation in advance; when the day-ahead predicted load command and the actual load command deviation are greater than the allowable value L, the deviation between the advance optimization calculation result and the actual thermal storage optimal output value exceeds the allowable range, and at this time, the frequency regulation command response is performed according to the current thermal storage output coordination mode of the corresponding power plant, that is, the pre-calculated thermal storage optimized output value cannot be used at this time.

[0052] In step S6, the charge state of the energy storage battery is pre-adjusted, provided that the thermal power unit and the energy storage battery have responded to the previous frequency modulation instruction, the frequency modulation performance evaluation indicators on the grid side have all been evaluated, and the new frequency modulation instruction has not yet appeared; at this time, the thermal power unit will make a small range of power fluctuations near the required power due to inertia, and the fluctuating power is used to pre-charge and discharge the energy storage, that is, adjust the charge state.

[0053] The pre-charging and discharging refers to the energy storage battery state of charge change trend chart obtained by pre-optimization calculation, and the current state of charge is adjusted according to the direction and size of the state of charge change at the next time point in the trend chart. The adjustment goal is to make the energy storage state of charge away from the upper and lower limits of 0.2 or 0.8 at one time point every 5 minutes, so as to improve the energy storage availability.

[0054] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0055] (1) The present invention can make the thermal power units and energy storage batteries approach the theoretical optimum of the total economic benefits of the thermal-storage combined frequency regulation system when responding to the power grid frequency regulation instructions. Over a long period of time, the thermal-storage frequency regulation mode under optimized output will bring comprehensive and integrated benefits to the power plant side, mainly reducing the frequency regulation loss cost on the power plant side.

[0056] (2) When the energy storage battery is pre-charged and discharged, a more directional power adjustment can be performed based on the charge state trend diagram obtained by optimization calculation, so that the availability index of the energy storage battery is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a flow chart of the method of the present invention;

[0058] Figure 2 It is a schematic diagram of the structure of the fire-storage joint frequency modulation system;

[0059] Figure 3 It is the day-ahead load curve of thermal power units issued by the power grid in advance on a certain day;

[0060] Figure 4 It is the flow chart of the optimization calculation method of this paper;

[0061] Figure 5 This is the schematic diagram of optimized output of thermal energy storage combined frequency regulation in the calculation example;

[0062] Figure 6 It is the state of charge trend diagram of the energy storage battery in the example. DETAILED DESCRIPTION

[0063] The following will describe the technical solution in detail with the help of simulation examples and attached drawings:

[0064] like Figure 1 As shown in FIG. 1 , a method for optimizing the configuration of a thermal-storage combined frequency regulation system considering the best economic benefits includes:

[0065] S1: Establish a mathematical model for the total cost loss of the thermal power generation combined frequency regulation system. First, establish a cost loss model for the coal consumption of the thermal power unit frequency regulation, which is divided into steady-state coal consumption modeling and transient coal consumption modeling. Steady-state coal consumption modeling involves the amount of coal consumed per unit of power generation when the thermal power unit is at a certain fixed power output. The coal consumption data of various types of main units in China can be fitted and regressed to obtain a model for the change of power and coal consumption of the thermal power unit. The basic mathematical model is as follows:

[0066]

[0067] Where: m wen is the power supply coal consumption of the thermal power unit in steady state, g / (kW h); P is the unit load, MW; m0 is the reference coal consumption, g / (kWh); P0 is the reference load, MW; the rest are fitting coefficients.

[0068] Transient coal consumption mainly reflects the transient coal consumption increment caused by the thermal power unit in the process of load change, which is related to the frequency modulation rate of the thermal power unit. The model can be modeled by referring to the relevant dynamic model data. The final fitting model of the coal consumption cost of the thermal power unit is as follows:

[0069]

[0070] Where: C mei is the coal consumption cost per hour; V e The load rate of the thermal power unit, MW / min; C price Real-time coal price.

[0071] Secondly, the environmental protection payment cost during the frequency regulation of thermal power units is also taken into account in the optimization objective function. For the unit pollutant emission cost, NOx and SO2 are mainly considered, as shown in the following formula:

[0072]

[0073] Where: λ is the adjustment coefficient; P NOx , P SO2 are the emission values ​​of NOx and SO2 respectively; N1 and N2 are the equivalent values ​​of NOx and SO2 emission values ​​respectively.

[0074] The pollutant emission value of the unit is closely related to the working efficiency of its environmental protection equipment. Here, the fitting model of the unit operating conditions and the removal efficiency of the environmental protection equipment is constructed with reference to the dynamic model data. Taking the pollutant NOx as an example, the following emission calculation model is available:

[0075]

[0076] Where: b tp is the coal consumption for power generation, g / (kWh); N is the percentage of nitrogen in coal; P is the unit operating value, MW; η m is the fuel nitrogen conversion rate; n is 80%; m1 = 1×10 -8 , m2=1.2×10 -6 , m3=6×10 -4 , m4=0.082.

[0077] Further considering the frequency modulation life loss cost of energy storage batteries, mainly considering its discharge life loss cost. The total effective discharge amount during its life cycle can be expressed by the following formula:

[0078] Γ R =L R D R C R

[0079] Where: L R is the rated cycle life of the battery; D R is the rated discharge depth; C R is the rated capacity of the battery.

[0080] The life loss cost is estimated by converting the ratio of each discharge amount to the total effective discharge amount, as follows:

[0081]

[0082] Where: C ini is the initial investment cost of the battery; d is the single discharge ampere-hours during each load change process.

[0083] Finally, the above cost categories are superimposed to obtain the total cost loss model of thermal storage combined frequency regulation as follows:

[0084] C zong =C mei +C pai +C batlife

[0085] S2: The total cost loss mathematical model minus the grid frequency regulation compensation benefit model is used to obtain the total economic benefit model of the thermal storage combined frequency regulation system, which enriches the optimization objective function. The grid side will assess and compensate the comprehensive regulation of the thermal storage combined frequency regulation system, which can be described by the following formula:

[0086] Gain=KDQ

[0087] Among them: K is the comprehensive performance index of frequency regulation, which can be calculated by referring to the compensation details of the corresponding power grid; D is the frequency regulation mileage, which generally refers to the absolute value of the difference between the actual output and the initial output of the unit after responding to the command, MW; Q is the frequency regulation compensation price, which is set at 5-10 yuan / MW here.

[0088] In this way, the total economic benefit model of the thermal storage combined frequency regulation system is obtained by subtracting the benefits from the costs, which is also the total objective function of the optimization calculation as follows:

[0089] OBJ=C zong -Gain

[0090] S3: Select the load curve of the thermal power unit sent in advance by the power grid as the equality constraint condition to be satisfied for optimization, and perform optimization calculation under the inequality constraint condition that meets the basic upper and lower limits of the power of the thermal power unit and the energy storage battery. The day-ahead load curve of the thermal power unit here is the load forecast curve for the next day sent in advance by the power grid side, which has reference value. The sum of the output of the thermal power unit and the energy storage battery should be adjusted with the command value as the adjustment target to meet the basic command power requirements. In addition, the relevant inequality constraints must also be satisfied during optimization as shown below:

[0091]

[0092] The above formula shows that the optimized output value of the thermal power unit should be obtained between its minimum allowable value and maximum allowable value.

[0093]

[0094] The above formula shows that the optimized output value of the energy storage battery should be obtained between its minimum allowable value and maximum allowable value.

[0095] S4: The artificial bee colony optimization algorithm is used to calculate the optimal output of the thermal power unit and the energy storage and obtain the trend diagram of the energy storage charge state. The use process of the artificial bee colony optimization algorithm in this model is as follows: Figure 4 As shown, the optimized output value of the thermal-storage combined frequency regulation system is finally calculated and the change trend diagram of the energy storage charge state can be further obtained.

[0096] S5: Apply the optimized thermal storage output value obtained by optimization calculation to the thermal storage combined frequency regulation and load change process so that the total economic benefit of the thermal storage combined frequency regulation system during frequency regulation tends to the theoretical optimum; when applying it, it is necessary to first compare the load command forecast value issued in advance by the power grid side with the actual load command value, that is, when the deviation between the predicted load command and the actual load command value is less than a certain allowable value L=5MW, the thermal storage optimal output value calculated in advance is applied to the load change process with a small load command deviation, which is equivalent to an optimization calculation in advance. For example, the frequency regulation command of the unit at this time is P1MW, the current output is P2MW, and the advance forecast is (P1+2)MW. At this time, the deviation between the predicted value and the actual command is less than the allowable value, the unit optimized output calculated in advance is P3MW, and the energy storage battery optimized output is P4MW. The time interval is 5 minutes, so the rate allocated to the unit should be as shown in the following formula:

[0097]

[0098] Where: Vubest is the optimal load change rate assigned to the unit at this time, MW / min;

[0099] That is, when the thermal energy storage combined frequency regulation system responds to the P1 instruction, since the deviation between the predicted value and the actual value is small, the pre-calculated optimization value is used at this time, that is, the response rate assigned to the unit is Vubest MW / min, and the energy storage battery assists the unit with the optimized output P4 during the instruction response process. The pre-optimization goal is to maximize the total economic benefits of the thermal energy storage combined frequency regulation system, so the application of the optimized output at this time can maximize the optimization goal, that is, the total economic benefits of the thermal energy storage combined frequency regulation system;

[0100] In addition, when the deviation between the day-ahead predicted load command and the actual load command is greater than the allowable value L, the deviation between the advance optimization calculation result and the actual optimal thermal storage output value exceeds the allowable range. At this time, the frequency regulation command response can be carried out according to the current thermal storage output coordination method of the corresponding power plant, that is, the pre-calculated thermal storage optimization output value cannot be used at this time.

[0101] S6: Pre-adjust the state of charge of the energy storage battery, provided that the thermal power unit and the energy storage battery have responded to the previous frequency regulation instruction, the frequency regulation performance evaluation indicators on the grid side have all been evaluated and the new frequency regulation instruction has not yet appeared; at this time, due to inertia, the thermal power unit will make a small range of power fluctuations near the required power, and use this fluctuating power to pre-charge and discharge the energy storage, that is, adjust the state of charge.

[0102] The pre-charging and discharging refers to the energy storage battery state of charge change trend chart obtained by pre-optimization calculation, and the current state of charge is adjusted according to the direction and size of the state of charge change at the next time point in the trend chart. The adjustment goal is to make the energy storage state of charge away from the upper and lower limits of 0.2 or 0.8 at one time point every 5 minutes, so as to improve the energy storage availability.

[0103] The following is an explanation of steps S5 and S6 based on the simulation results:

[0104] Taking the load curve of the thermal power unit received by the power plant on a certain day as the equation constraint condition of the calculation example, the power of the thermal power unit is 330MW, the maximum charge and discharge power of the energy storage battery is 9MW, and the capacity is 4.5MWh. Figure 4 The calculation process of the optimization algorithm shown in the figure first calculates the optimized output value of the combined frequency regulation of fire and storage, and the result is as follows: Figure 5 As shown. An optimization calculation point is calculated every 5 minutes, and the calculation result is the optimized output value of the combined frequency regulation of thermal storage that makes the total economic benefits of the combined frequency regulation system of thermal storage tend to be optimal under the constraints of the instruction requirements. The change trend of the state of charge of the energy storage battery under the optimized output response is further drawn as shown in Figure 6 shown.

[0105] Combination Figure 6 Further explanation of the method for pre-adjusting the energy storage charge state: the optimization calculation time interval is 5 minutes, and the actual frequency regulation instruction does not appear regularly, so each time a new frequency regulation instruction appears, the optimized output is the optimized output value at the previous time point when it appears. The pre-adjustment of the energy storage charge state should be based on the change trend value at the next time point during the response waiting time, that is, the trend value of the energy storage charge state at the previous 5 minutes. When the current frequency regulation instruction has been responded to, the grid-side frequency regulation assessment indicators have been assessed, and a new frequency regulation instruction has not yet appeared, the energy storage battery charge state is pre-adjusted. At this time, according to Figure 6 Find out the energy storage charge state value at the next 5-minute time point closest to the time line, and pre-charge and discharge according to its change direction.

[0106] If in the next 5 minutes Figure 6 The state of charge value is about to increase. At this time, while waiting for the new frequency regulation instruction, the unit's fluctuating power is used to pre-discharge the energy storage, that is, a certain amount of electricity is released in advance to make the energy storage state of charge away from the upper limit of 0.8. If the state of charge value decreases, the method is similar. In addition, the length of time for the frequency regulation waiting instruction is not fixed, so the upper and lower limits of pre-charge and discharge of 0.4 or 0.6 are set to limit it. If the pre-charge and discharge has caused the energy storage state of charge value to reach the limit of 0.4 or 0.6, the pre-charge and discharge will stop immediately. If a new frequency regulation instruction has appeared, the pre-charge and discharge of the energy storage will also stop immediately, and a new round of optimized output response process will begin.

[0107] For S5 and S6: a constant rate response method can be set as a control. In this response method, the thermal power unit always selects the maximum regulation rate it can reach to respond, and the energy storage makes up for the power difference. Select an 8-hour frequency regulation instruction historical data segment, and compare the advantages and disadvantages of the simulation results of this method by calculating the corresponding cost and frequency regulation benefit items. As shown in the following table:

[0108] Table 1 Comparison results of 8-hour simulation between the constant rate response method and the optimized rate response method in this paper

[0109]

[0110]

[0111] From the simulation calculation results in the above table, it can be seen that the same 8-hour frequency regulation instruction historical data, but different thermal storage response methods will affect the frequency regulation costs in various dimensions and the total economic benefits. After the optimized output is used for response, the total economic benefits have been improved to a certain extent, which is mainly reflected in the reduction of total coal consumption costs, the reduction of environmental costs and the increase of frequency regulation benefits in Table 1. Since the thermal power units use optimized output for response, in some periods, energy storage needs to discharge more to respond to the requirements of the frequency regulation instructions. The increase in discharge ampere-hours leads to a certain increase in the life depreciation cost of energy storage, but the total economic benefits are better than the constant rate response method. In addition, since the charge state of energy storage is pre-adjusted during the waiting period of the frequency regulation instruction, the charge state of the energy storage battery will be as far away from the upper and lower limits of 0.8 or 0.2 as possible, which improves its availability during the frequency regulation period, which also ensures that the total economic benefits of the thermal storage combined frequency regulation system tend to be better.

Claims

1. A method for optimizing the configuration of a combined frequency modulation system of a thermal power plant and a storage system, characterized in that: The method comprises the following steps: S1: A mathematical model of total cost loss of the thermal-storage combined frequency regulation system was established; S2: The total cost loss mathematical model minus the power grid frequency regulation compensation benefit model is used to obtain the total economic benefit model of the thermal-storage combined frequency regulation system; S3: Select the load curve of the thermal power unit issued by the power grid in advance as the equality constraint condition to be satisfied for optimization. At the same time, perform optimization calculation under the inequality constraint condition that meets the basic upper and lower power limits of the thermal power unit and the energy storage battery to obtain the thermal storage optimized output value. S4: Using artificial bee colony optimization algorithm to calculate the optimal output of thermal power units and energy storage and obtain the trend diagram of energy storage charge state; S5: Apply the optimized output value of the thermal storage obtained by the optimization calculation to the thermal storage combined frequency regulation and load changing process so that the total economic benefit of the thermal storage combined frequency regulation system during frequency regulation tends to the theoretical optimum; S6: According to the obtained energy storage charge state change trend diagram, during the frequency modulation waiting instruction process, the energy storage battery charge state is pre-adjusted by using the fluctuating power of the thermal power unit, so that the energy storage battery charge state, i.e., the SOC value, is far away from the upper and lower limit requirements of 0.2 or 0.8, thereby improving its availability index.

2. The method for optimizing configuration of a combined frequency modulation system of a thermal power plant and a storage system according to claim 1, characterized in that: The step S1 comprises: respectively modeling the cost losses of the thermal power unit and the energy storage battery in the frequency regulation process; firstly, the frequency regulation cost modeling of the thermal power unit takes into account the frequency regulation coal consumption cost modeling and the environmental protection payment cost modeling of the thermal power unit, and the frequency regulation coal consumption cost modeling of the thermal power unit is subdivided into steady-state coal consumption modeling and transient coal consumption modeling, and the environmental protection payment cost modeling of the thermal power unit is the environmental payment cost modeling caused by the unit's pollutant emissions; secondly, the cost loss modeling of the energy storage battery in the frequency regulation process is the life depreciation cost modeling caused by its discharge; finally, the frequency regulation coal consumption cost model and the environmental protection payment cost model of the thermal power unit are added to the life depreciation cost model of the energy storage battery in the frequency regulation process to obtain the total cost loss mathematical model of the thermal-storage combined frequency regulation system.

3. The method for optimizing the configuration of the combined frequency modulation system of fire and storage as claimed in claim 2, characterized in that: The total cost loss mathematical model of the fire-storage combined frequency regulation system is: C zong =C mei +C pai +C batlife Where: C zong is the total loss cost of the combined frequency regulation process of thermal energy storage; C mei is the total coal consumption cost of the combined frequency regulation process of thermal power plant and fuel storage; C pai Environmental protection payment cost for the combined frequency regulation process of thermal energy storage; C batlife The battery life loss cost for the thermal-storage combined frequency regulation process; The coal consumption cost fitting model of thermal power units is as follows: C mei =(a1V e 3 +a2V e 2 +a3V e +a4+m wen )×P×C price Where: C mei is the coal consumption cost per hour; V e Adjust the load rate for thermal power units; C price is the real-time coal price, m wen is the coal consumption of thermal power units in steady state, P is the unit load, a1, a2, a3, and a4 are 0.003, 0.013, 0.001, and -0.176 respectively; The environmental protection payment cost model is as follows: Where: λ is the adjustment coefficient; P NOx , P SO2 are the emission values ​​of NOx and SO2 respectively; N1 and N2 are the equivalent values ​​of NOx and SO2 emission values ​​respectively; The life-cycle depreciation cost model of energy storage is as follows: C ini is the initial investment cost of the battery; d is the single discharge ampere-hour of each load change process; the total effective discharge capacity during the life cycle can be expressed by the following formula: C R =L R D R C R Where: L R is the rated cycle life of the battery; D R is the rated discharge depth; C R is the rated capacity of the battery.

4. The method for optimizing configuration of a combined frequency modulation system of a fire and a storage system according to claim 2, characterized in that: The steady-state coal consumption modeling involves the amount of coal consumed per unit of power generation when the thermal power unit is at a certain fixed power output. The fitting and regression analysis of coal consumption data of various types of main units are performed to obtain the change model of power and coal consumption of thermal power units; its basic mathematical model is as follows: Where: m wen is the coal consumption of thermal power unit in steady state, P is the unit load; m0 is the reference coal consumption, P0 is the reference load; a=0.798; b=0.988; u0=0.0035; t=0.245; β0=-0.0348.

5. The method for optimizing configuration of a combined frequency modulation system of a thermal energy storage system according to claim 2 or 3, characterized in that: In step S2, the total cost loss mathematical model C zong Subtract the power grid frequency regulation compensation benefit model Gain to obtain the total economic benefit model OBJ of the thermal-storage combined frequency regulation system. OBJ=C zong -Gain The grid frequency regulation compensation revenue model Gain is: Gain=KDQ Among them: K is the comprehensive performance index of frequency regulation, D is the frequency regulation mileage, which generally refers to the absolute value of the difference between the actual output and the initial output after the unit responds to the command, and Q is the frequency regulation compensation price.

6. The method for optimizing configuration of a combined frequency modulation system of a thermal energy storage system according to claim 1, characterized in that: In step S3, the load curve of the thermal power unit sent in advance by the power grid is selected as the equality constraint condition to be satisfied for optimization, and the optimization calculation is performed under the inequality constraint condition that meets the basic upper and lower limits of the power of the thermal power unit and the energy storage battery. The day-ahead load curve of the thermal power unit is the load forecast curve for the next day sent in advance by the power grid side. The sum of the output of the thermal power unit and the energy storage battery should take the command value as the adjustment target to meet the basic command power requirement, and obtain the thermal storage optimized output value: The above formula shows that the optimized output value of the thermal power unit should be obtained between its minimum allowable value and maximum allowable value; The above formula shows that the optimized output value of the energy storage battery should be obtained between its minimum allowable value and maximum allowable value.

7. The method for optimizing configuration of a combined frequency modulation system of a thermal power plant and a storage system according to claim 1, characterized in that: In step S4, the artificial bee colony optimization algorithm is used to calculate the optimal output of the thermal power unit and the energy storage and obtain the trend diagram of the change of the energy storage charge state; the algorithm logic sequence of the artificial bee colony optimization algorithm under the present method model is as follows: the first step is to initialize, input the basic parameters of the thermal storage equipment such as power limit, then input the parameters of the artificial bee colony optimization algorithm such as determining the number of bees to be 200, the maximum number of iterations to be 300, and generate the initial random solution x i , i = 1, 2, ..., 100; in the second step, the employed bees generate new random solutions s in the neighborhood of the initial random solution according to the formula ij , calculate and compare the advantages and disadvantages of the new solution and the initial solution, and keep the solution with better fitness; s ij =x ij +β ij (x ij -x kj ) Where: k∈{1,2,...,100},k≠i; j∈{1,2}; β ij A random number between -1 and 1; In the third step, the employed bee shares the solution information with the follower bee and calculates the probability value of each solution according to the following formula: Among them: fit i is the fitness value corresponding to each solution, that is, the quality of the solution. Then, based on the roulette method, a random number is generated between -1 and 1. If the random number is less than the probability value of the solution, the current optimal solution is retained according to the steps in the second step. After the follower bee search is completed in the fourth step, check whether there is a local optimal solution, that is, whether there is a solution that has not been updated for more than the maximum number of unupdated times M. If so, the local optimal solution is discarded and a new solution is generated according to the following formula: x ij =x mini +α(x maxj -x minj ) Among them: α is a random number between 0 and 1; x mini 、x maxj 、x minj is the minimum and maximum value of the solution of the corresponding dimension; then repeat the above steps; The fifth step is to check whether the maximum number of iterations 300 has been reached. If so, the optimal solution can be output; Finally, the optimized output value of the thermal-storage combined frequency regulation system is obtained, and further the changing trend diagram of the energy storage charge state is obtained.

8. The method for optimizing configuration of a combined frequency modulation system of a thermal power plant and a storage system according to claim 1, characterized in that: In the step S5, the optimized output value of the thermal storage obtained by the optimization calculation is applied to the thermal storage combined frequency regulation and load change process so that the total economic benefit of the thermal storage combined frequency regulation system during frequency regulation tends to be theoretically optimal; when applying it, it is necessary to first compare the load command forecast value issued in advance by the power grid side with the actual load command value, that is, when the deviation between the day-ahead predicted load command and the actual load command value is less than a certain allowable value L, the thermal storage optimal output value calculated in advance is applied to the load change process with a smaller load command deviation, which is equivalent to performing optimization calculation in advance; when the day-ahead predicted load command and the actual load command deviation are greater than the allowable value L, the deviation between the advance optimization calculation result and the actual thermal storage optimal output value exceeds the allowable range, and at this time, the frequency regulation command response is performed according to the current thermal storage output coordination mode of the corresponding power plant, that is, the pre-calculated thermal storage optimized output value cannot be used at this time.

9. The method for optimizing configuration of a combined frequency modulation system of a thermal energy storage system according to claim 1, characterized in that: In step S6, the charge state of the energy storage battery is pre-adjusted, provided that at this time the thermal power unit and the energy storage battery have responded to the previous frequency modulation instruction, the frequency modulation performance evaluation indicators on the grid side have all been evaluated and the new frequency modulation instruction has not yet appeared; at this time, due to inertia, the thermal power unit will make a small range of power fluctuations near the required power, and the fluctuating power is used to pre-charge and discharge the energy storage, that is, adjust the charge state.

10. The method for optimizing configuration of a combined frequency modulation system of a thermal power plant and a storage system according to claim 9, characterized in that: The pre-charging and discharging refers to the energy storage battery state of charge change trend chart obtained by pre-optimization calculation, and the current state of charge is adjusted according to the direction and size of the state of charge change at the next time point in the trend chart. The adjustment goal is to make the energy storage state of charge away from the upper and lower limits of 0.2 or 0.8 at one time point every 5 minutes, so as to improve the energy storage availability.

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