Energy storage control method for reducing peak-valley difference rate of source network load storage integrated system

Abstract

The invention provides an energy storage control method for reducing the peak-valley difference rate of a source-grid-load-storage integrated system, and the method comprises the steps: comparing the load peak-valley difference rate with the system peak-valley difference rate interpolation when the stored energy does not participate in the adjustment of the peak-valley difference rate based on a predicted new energy output and load characteristic curve, calculating the adjustment amount of a current peak-valley value and a target peak-valley value, and carrying out the calculation of the adjustment amount of the current peak-valley value and the target peak-valley value. And meanwhile, the target peak-valley difference rate is dynamically adjusted according to the real-time charge state and power limitation of the energy storage in the actual adjustment process of the energy storage, so that the adjustment capability of the energy storage is explored as much as possible, and the peak-valley difference rate of the system in a new energy output fluctuation scene is reduced. The method can be suitable for solving the peak-valley difference rate energy storage charging and discharging strategy under various complex working conditions in the source-grid-load-storage integrated system, the application range is wide, solving is convenient, and a scientific and reasonable analysis and control scheme can be provided for safe and stable operation of the source-grid-load-storage integrated system.

Description

Technical Field

[0001] The present invention relates to the field of source-grid-load-storage energy storage control technology, in particular to the field of energy management and control of a source-grid-load-storage integrated system, and specifically to an energy storage control method for reducing the peak-to-valley difference rate of a source-grid-load-storage integrated system. Background Art

[0002] The source-grid-load-storage integrated system is a system that combines renewable energy generation, grid power supply and energy storage technology. It has the characteristics of tightly integrating distributed generation, grid and energy storage systems. In such a system, energy storage control plays an important role. Energy storage control can help balance the supply and demand of the grid by adjusting the charging and discharging state of the energy storage system. When the grid load is too high, the energy storage system can release electric energy to relieve the pressure; when the grid load is low, the energy storage system can absorb excess electric energy for storage. This regulation capability helps to improve the stability and reliability of the grid. The specific methods and strategies of energy storage control can vary according to different energy storage technologies and application scenarios. Common energy storage control strategies include:

[0003] Peak-valley balance charging and discharging strategy: This strategy aims to reduce the peak-valley difference of grid load by storing electric energy during peak load periods and releasing electric energy during low load periods. By monitoring the grid load curve and renewable energy generation, the appropriate time for charging and discharging operations is determined to achieve peak-valley balance.

[0004] Time-optimized charging and discharging strategy: This strategy optimizes the charging and discharging behavior of the energy storage system in different time periods based on factors such as electricity market prices, grid load demand, and renewable energy supply. For example, charging is performed during periods when electricity prices are low, and discharging is performed during periods when electricity demand is high, to maximize economic benefits.

[0005] Frequency regulation strategy: The energy storage system can be used as a frequency regulation device to monitor changes in grid frequency and provide corresponding charge and discharge regulation capabilities as needed. When the grid frequency deviates from the standard range, the energy storage system can respond quickly and regulate power through charge and discharge to help maintain the stability of the grid frequency.

[0006] Energy storage capacity management strategy: This strategy is used to manage the capacity of the energy storage system to ensure that the system operates within the appropriate capacity range. By monitoring and controlling the charging and discharging status, temperature, health status and other parameters of the energy storage system, overcharging or over-discharging can be avoided, extending the life and performance of the energy storage system.

[0007] Intelligent energy management and optimization strategy: By applying intelligent algorithms and optimization methods, the energy of the energy storage system is managed and dispatched to maximize energy efficiency and economic benefits. This includes intelligent dispatching of energy collection, storage, distribution and utilization, and optimizing the control of energy flow according to grid demand and renewable energy supply.

[0008] Emergency backup power strategy: The energy storage system can be used as an emergency backup power source and quickly put into power supply in the event of a grid failure or other emergency. Through a reasonable control strategy, the energy storage system is always in a standby state to provide reliable emergency power support.

[0009] However, the above adjustment method does not take into account the peak-to-valley difference rate of the source-grid-load-storage system. The current regional power grid requires that the peak-to-valley difference rate of the source-grid-load-storage system should not be higher than the natural peak-to-valley difference rate of the load when it is connected to the grid, so as to minimize the impact of the volatility and intermittency of renewable energy output on the public power grid. Therefore, the current energy storage control strategy cannot fully meet this requirement. Summary of the invention

[0010] The purpose of the present invention is to provide an energy storage control method for reducing the peak-to-valley difference rate of a source-grid-load-storage integrated system. The method is based on the predicted new energy output and load characteristic curve, takes into account the peak-to-valley difference rate of the system's external power receiving characteristics, and interpolates the load peak-to-valley difference rate with the system peak-to-valley difference rate when the energy storage does not participate in the peak-to-valley difference rate regulation. The adjustment amount between the current peak-to-valley value and the target peak-to-valley value is calculated. At the same time, in the actual regulation process of the energy storage, the target peak-to-valley difference rate is dynamically adjusted according to the real-time charge state and power limit of the energy storage, so as to explore the regulation ability of the energy storage as much as possible, thereby reducing the system peak-to-valley difference rate under the scenario of new energy output fluctuation.

[0011] To achieve the above object, the present invention adopts the following technical solutions:

[0012] Step 1: Forecast the output of wind power, photovoltaic and other new energy sources in a control cycle, calculate the natural peak-to-valley difference rate of the load, and obtain the new energy output curve and load characteristic curve;

[0013] Step 2: Based on the new energy output curve and load characteristic curve in step 1, analyze and compare the natural peak-to-valley difference rate of the load in step 1 with the peak-to-valley difference rate when the energy storage charging and discharging strategy does not participate in the peak-to-valley difference rate regulation. If the natural peak-to-valley difference rate of the load satisfies the condition that it is greater than the peak-to-valley difference rate when the energy storage charging and discharging strategy does not participate in the peak-to-valley difference rate regulation, stop the calculation of the control cycle. If not, proceed to step 3.

[0014] Step 3: Adjust the charging and discharging strategy of the energy storage with the goal of reducing the peak-to-valley rate of the system.

[0015] The details are as follows:

[0016] Step 1:

[0017] The load peak-to-valley difference rate is an indicator used to measure the degree of difference between the peak and valley values ​​in the power load curve. When calculating the peak-to-valley difference rate, you first need to collect load data, usually sampled every hour or every 15 minutes. These data can be actual measured load data or simulated or predicted load data. Then, the peak and valley values ​​are identified from the load data. The peak value is the highest point in the load curve, indicating the moment when the load demand is the largest; the valley value is the lowest point in the load curve, indicating the moment when the load demand is the smallest. Finally, the load peak-to-valley difference rate is calculated using the following formula:

[0018] g(P L )=(P L.max -P L.min ) / P L.max (1.1)

[0019] Among them, g(P L ) represents the natural peak-to-valley difference rate of the load, P L.max Indicates the peak value of the load curve in a day, P L.min Indicates the valley value of the load curve in a day;

[0020] Step 2:

[0021] In order to compare with the natural peak-valley difference of load, we first need to analyze the system's absorption when the energy storage is adjusted without considering the peak-valley difference based on the predicted new energy output curve and load characteristic curve;

[0022] When the energy storage control strategy does not consider the peak-to-valley difference rate, the following charging and discharging strategy is generally adopted:

[0023] (1) Let time T = 1;

[0024] (2) Verify P G (T)-P L (T) ≥ 0. If yes, go to step (3). If not, go to step (4).

[0025] (3) If P G (T)-P L (T)≥0, the output of new energy is greater than the power required by the load, and it is necessary to charge the energy storage. The charging power of the energy storage is determined by the real-time state of charge SOC of the energy storage and the maximum charging power P of the energy storage. b.max , and at this time P G (T)-P L The difference between (T) is determined by the following calculation method:

[0026] P b (T) = min{(1-SOC)Q B ,Pb.max ,P G (T)-P L (T)}(1.2)

[0027] Where Q B is the energy storage capacity, P b.max is the maximum charging power of the energy storage, min{·} is the minimum operator, P b is the charging and discharging power of the energy storage.

[0028] (4) If P G (T)-P L (T)<0, the output of new energy is less than the power required by the load, and energy storage is needed to discharge to the load. The discharge power of energy storage is determined by the real-time state of charge SOC of energy storage and the maximum charging power P of energy storage. b.max , and at this time P L (T)-P G The difference between (T) is determined by the following calculation method:

[0029] P b (T) = min{SOC × Q B ,P b.max ,P L (T)-P G (T)}(1.3)

[0030] (5) Calculate the energy storage charge state and external power at time T, and set T = T + 1. If T ≤ 24, go to step (1). If T > 24, stop the calculation. At this time, the energy storage charge and discharge plan for one day is [P b (1),P b (2),....,P b (twenty four)] T .

[0031] In the source-grid-load-storage system, the peak-valley difference rate is expressed as the ratio of the difference between the peak and valley values ​​of the external power receiving characteristics within a day to the peak value. The calculation model of the peak-valley difference rate in the source-grid-load-storage integrated system is:

[0032]

[0033] Where f(P max ,P min ) is the peak-to-valley difference rate of the external power receiving characteristics of the source-grid-load-storage integrated system, P max is the peak value of external power received by the source-grid-load-storage integrated system in one day, P min is the valley value of external power received by the source-grid-load-storage integrated system in one day, P L is the active power of the load, P G Contribute to the development of new energy; bis the charging and discharging power of the energy storage, the sign is positive when charging and negative when discharging. The charging and discharging power of the energy storage at each moment is [P b (T1),P b (T2),....,P b (T 24 )] T ,[T1,T2,....,T 24 ] is 24 moments in a day, with an interval of 1 hour; T max Peak P max The moment of appearance; T min is the moment when the valley value appears;

[0034] If the peak-to-valley difference rate f(P max ,P min ) is less than the natural peak-to-valley rate of the load g(P L ), it means that the source-load characteristics of the system are highly complementary on that day, and there is no need for energy storage to adjust the peak-to-valley difference rate; on the contrary, if the peak-to-valley difference rate f(P max ,P min ) is greater than the natural peak-to-valley rate of the load g(P L ), it is necessary to further adjust the charging and discharging plan of energy storage to reduce the peak-to-valley difference rate.

[0035] Step 3:

[0036] To reduce the peak-to-valley difference rate of the source-grid-load-storage system, the charging and discharging strategy of energy storage is adjusted. It is necessary to first compare the load peak-to-valley difference rate with the difference between the peak-to-valley difference rate of the system when the energy storage does not participate in the peak-to-valley difference rate adjustment, calculate the adjustment amount between the current peak-to-valley value and the target peak-to-valley value, and dynamically adjust the target peak-to-valley difference rate according to the real-time charge state and power limit of the energy storage during the actual adjustment process of the energy storage, so as to explore the adjustment capacity of the energy storage as much as possible, thereby achieving the goal of reducing the peak-to-valley difference rate of the system under the scenario of new energy output fluctuation. The specific methods are as follows:

[0037] (1) Compare the difference between load power consumption and renewable energy output at each moment, and based on this, modify the external power receiving characteristics of the source-grid-load-storage system, as follows. First, calculate the difference between power consumption and power generation at each moment:

[0038] P0=P L -P G (1.5)

[0039] Where P0 is the difference between power consumption and power generation at each moment. For moment T, if P0(T)≤0, the load power consumption is less than the output of new energy, and the external power receiving characteristics of the source-grid-load-storage system can be made 0 by abandoning power. Therefore, for the moment when P0(T)≤0, no additional adjustment is required for the charging and discharging of energy storage, and P0(T)=0 can be made; if P0(T)>0 at moment T, it is necessary to purchase electricity from the public grid to meet the actual load demand, and the external power receiving characteristics at this time are P0(T). Therefore, the following corrections are made to P0 at each moment to obtain the actual external power receiving characteristics:

[0040]

[0041] Where P(T) is the external power receiving characteristic.

[0042] (2) If the natural peak-to-valley difference of the load is used as a reference value, the following adjustments are made to the peak-to-valley value:

[0043]

[0044] Where P min and P max are the valley and peak values ​​of the external power receiving characteristics, max{·} is the maximum value operator, P(T1), P(T2), ..., P(T 24 ) is the external power received at each time of the day, λ is the adjustment coefficient of the peak and valley values, P′ min and P′ max In actual calculation, you can also set the target peak-to-valley difference rate by yourself instead of using the natural peak-to-valley difference rate of the load as the adjustment target.

[0045] (1) Based on the target peak and valley values, adjust the charging and discharging power of the energy storage at each moment. The specific method is as follows:

[0046] 1) For time T = 1, verify that P(T) < P' min Is it true? If so, go to step 2); if not, go to step 3);

[0047] 2) P(T)<P′ min When the external power is less than the target valley value, the energy storage needs to be charged to increase the external power. The charging power of the energy storage is determined by the real-time state of charge SOC of the energy storage and the maximum charging power P of the energy storage. b.max , and at this time P′ min -P(T), the charging power of energy storage is calculated by the following method:

[0048]

[0049] From the charging power of the energy storage, it can be inferred that the external power received by the source-grid-load-storage system at this time is:

[0050] P′(T)=P b (T)+P(T)(1.9)

[0051] Since the energy storage charging power is affected by other limiting factors, it may not be able to fully supplement P m ' in -P(T), resulting in the external power receiving characteristic P′(T) after energy storage charging still being less than the target valley value P m ' in , at this time, the target peak and valley values ​​need to be updated accordingly to achieve the peak-to-valley difference rate adjustment target in subsequent adjustments:

[0052]

[0053] 3) If P(T)≥P m ' in , the external power is greater than the target valley value, verifying that P(T)<P m ' ax Is it established? If not, go to step 4). If it is established, then the external power received by the source-grid-load-storage system meets the requirements of the peak-valley range. The energy storage can be charged and discharged according to the charge state of the energy storage within the peak-valley range as a backup for subsequent adjustments. The principle of energy storage charging and discharging is: when the remaining power of the energy storage is less than the minimum charging and discharging power, the energy storage needs to be charged. The energy storage charging leads to an increase in electricity demand, and the increased electricity demand should not be greater than the target peak value P m ' ax ; Charging power of energy storage; When the remaining chargeable capacity of energy storage is less than the minimum charge and discharge power, energy storage discharge is required. Energy storage discharge causes the external power to decrease. The external power after reduction should not be less than P m ' in , which can be calculated as:

[0054]

[0055] 4) If P(T)≥P m ' ax If the external power is greater than the target peak, the energy storage needs to be discharged to reduce the external power. The discharge power of the energy storage is determined by the real-time state of charge SOC of the energy storage and the maximum discharge power P of the energy storage. b.max , and at this time P(T)-P m ' ax The discharge power of energy storage is calculated by the following method:

[0056] P b (T) = -min{P b.max,SOC×Q B ,P(T)-P m ' ax}(1.12)

[0057] The external power P'(T) of the source-grid-load-storage system can be inferred from equation (1.9). Since the energy storage discharge power is affected by other limiting factors, it may not be able to fully supplement P(T)-P m ' ax The difference between the two causes the external power receiving characteristic P′(T) after the energy storage discharge to be still greater than the target peak value P m ' ax , at this time, the target peak and valley values ​​need to be updated accordingly to achieve the peak-to-valley difference rate adjustment target in subsequent adjustments:

[0058]

[0059] Since the adjustment directions of the target peak and valley values ​​are inconsistent due to different reasons, the operation of readjusting the target peak and valley values ​​due to the external power receiving characteristics after energy storage control not meeting the target peak or valley values ​​can only be implemented once within a planning cycle (usually one day). If the peak and valley values ​​have been adjusted due to one of the reasons in the cycle steps, the target peak and valley values ​​will no longer be adjusted due to another reason in the subsequent steps.

[0060] 1) Calculate the system state variables such as external power receiving and energy storage charge state at time T, and set T = T + 1. If T ≤ 24, go to step 1). If T > 24, stop calculating. At this time, the charge and discharge plan of energy storage within one day is [P b (1),P b (2),....,P b (twenty four)] T , the external power received is [P′(1),P′(2),....,P′(24)] T Based on this, the peak-to-valley difference rate f(P max ,P min )for:

[0061]

[0062] The beneficial results of the present invention are: by proposing a method for energy storage control that reduces the peak-to-valley difference rate of the source-grid-load-storage integrated system, the external power receiving characteristics of the source-grid-load-storage integrated system are adjusted, and the general principle of energy storage charging and discharging control considering the peak-to-valley difference rate in the scenario of new energy output fluctuation is given, thereby achieving the goal of reducing the peak-to-valley difference rate of the source-grid-load-storage system. The proposed method is based on the predicted new energy output and load characteristic curve, and by comparing the load peak-to-valley difference rate with the interpolation of the system peak-to-valley difference rate when the energy storage does not participate in the peak-to-valley difference rate adjustment, the adjustment amount of the current peak-to-valley value and the target peak-to-valley value is calculated. At the same time, in the actual adjustment process of the energy storage, the target peak-to-valley difference rate is dynamically adjusted according to the real-time charge state and power limit of the energy storage, so as to explore the adjustment ability of the energy storage as much as possible, thereby reducing the system peak-to-valley difference rate in the scenario of new energy output fluctuation. The advantage of this method is that it can dynamically adjust the peak-to-valley target value according to the real-time state of charge of the energy storage system, is suitable for the scenario of new energy output fluctuation, and has a high adjustment efficiency. It can be applied to solve the peak-to-valley rate energy storage charging and discharging strategies under various complex working conditions in the source-grid-load-storage integrated system. It has a wide range of applications and is easy to solve. It can provide scientific and reasonable analysis and control solutions for the safe and stable operation of the source-grid-load-storage integrated system. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is the characteristic curve of the new energy output load on a typical day;

[0064] Figure 2 It is the external power receiving characteristics of the system before and after energy storage participates in peak-valley rate regulation. DETAILED DESCRIPTION

[0065] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0066] This embodiment takes a grid-connected source-grid-load-storage integrated system that combines wind and solar power to supply power to a chemical material manufacturing enterprise as an example. In order to verify the effectiveness of the proposed method, the source-grid-load-storage integrated demonstration project in the example plans a total of 150MW wind power and 200MWp photovoltaic power, and is equipped with 25% / 4h energy storage equipment to supply power to chemical enterprises. Therefore, taking the natural peak-to-valley difference rate of the load as the adjustment target, the peak-to-valley difference rate of the source-grid-load-storage integrated system is adjusted according to the charging and discharging strategy of the energy storage. Next, it is verified through a typical day scenario, and the typical day new energy output curve and load power consumption curve and corresponding data are selected for analysis, and then it is verified that the peak-to-valley difference rate of the system can be significantly reduced under the adjustment strategy proposed in the present invention.

[0067] Typical daily wind power, photovoltaic output and load characteristics are shown in Table 1.

[0068] Table 1 Typical daily operation data table (unit: MW)

[0069]

[0070]

[0071] 1. Forecast the output of new energy sources such as wind power and photovoltaic power, and calculate the natural peak-to-valley difference rate of load;

[0072] The load peak-to-valley difference rate is an indicator used to measure the degree of difference between the peak and valley values ​​in the power load curve. When calculating the peak-to-valley difference rate, you first need to collect load data, usually sampled every hour or every 15 minutes. These data can be actual measured load data or simulated or predicted load data. Then, the peak and valley values ​​are identified from the load data. The peak value is the highest point in the load curve, indicating the moment when the load demand is the largest; the valley value is the lowest point in the load curve, indicating the moment when the load demand is the smallest. Finally, the load peak-to-valley difference rate is calculated using the following formula:

[0073] g(P L )=(P L.max -P L.min ) / P L.max

[0074] Among them, g(P L ) represents the natural peak-to-valley difference rate of the load, P L.max Indicates the peak value of the load curve in a day, P L.min Indicates the valley value of the load curve in a day;

[0075] The natural peak-to-valley difference rate of the load calculated by the above method is:

[0076] 2. Based on the predicted new energy output curve and load characteristic curve, analyze the system's absorption when the energy storage is adjusted without considering the peak-to-valley difference rate;

[0077] When the energy storage control strategy does not consider the peak-to-valley difference rate, the following charging and discharging strategy is generally adopted:

[0078] (1) Let time T = 1;

[0079] (2) Verify P G (T)-P L (T) ≥ 0. If yes, go to step (3). If not, go to step (4).

[0080] (3) If P G (T)-P L(T)≥0, the output of new energy is greater than the power required by the load, and it is necessary to charge the energy storage. The charging power of the energy storage is determined by the real-time state of charge SOC of the energy storage and the maximum charging power P of the energy storage. b.max , and at this time P G (T)-P L The difference between (T) is determined by the following calculation method:

[0081] P b (T) = min{(1-SOC)Q B ,P b.max ,P G (T)-P L (T)}

[0082] Where Q B is the energy storage capacity, P b.max is the maximum charging power of the energy storage, min{·} is the minimum operator, P b is the charging and discharging power of the energy storage.

[0083] (4) If P G (T)-P L (T)<0, the output of new energy is less than the power required by the load, and energy storage is needed to discharge to the load. The discharge power of energy storage is determined by the real-time state of charge SOC of energy storage and the maximum charging power P of energy storage. b.max , and at this time P L (T)-P G The difference between (T) is determined by the following calculation method:

[0084] P b (T) = min{SOC × Q B ,P b.max ,P L (T)-P G (T)}

[0085] (5) Calculate the energy storage charge state and external power at time T, and set T = T + 1. If T ≤ 24, go to step (1). If T > 24, stop calculating. At this time, the energy storage charge and discharge plan for one day is [P b (1),P b (2),....,P b (twenty four)] T ;

[0086] The above method calculates that the energy storage charge and discharge plan for one day is [-87.5, 0, ..., 0,]. That is, the energy storage discharges 87.5MW at the first moment to supplement the power demand of the load. After that, the load demand has been greater than the output of new energy, and the energy storage cannot charge and accumulate electricity. Therefore, the subsequent charge and discharge are 0MW. At this time, the external power receiving characteristics of the system are shown in Table 2.

[0087] Table 2 External power data table of source-grid-load-storage system

[0088]

[0089]

[0090] 3. When calculating energy storage without considering the peak-to-valley difference rate, the peak-to-valley difference rate of the source-grid-load-storage integrated system.

[0091] In the source-grid-load-storage system, the peak-valley difference rate is expressed as the ratio of the difference between the peak and valley values ​​of the external power receiving characteristics within a day to the peak value. The calculation model of the peak-valley difference rate in the source-grid-load-storage integrated system is:

[0092]

[0093] Where f(P max ,P min ) is the peak-to-valley difference rate of the external power receiving characteristics of the source-grid-load-storage integrated system, P max is the peak value of external power received by the source-grid-load-storage integrated system in one day, P min is the valley value of external power received by the source-grid-load-storage integrated system in one day, P L is the active power of the load, P G Contribute to the development of new energy; b is the charging and discharging power of the energy storage, the sign is positive when charging and negative when discharging. The charging and discharging power of the energy storage at each moment is [P b (T1),P b (T2),....,P b (T 24 )] T ,[T1,T2,....,T 24 ] is 24 moments in a day, with an interval of 1 hour; T max Peak P max The moment of appearance; T min is the moment when the valley value appears;

[0094] The above method calculates that when the energy storage is charged and discharged without considering the peak-to-valley difference rate, the peak-to-valley difference rate of the system is The peak-to-valley difference rate is greater than the natural peak-to-valley difference rate of the load of 0.353, and the charging and discharging plan of the energy storage needs to be further adjusted to reduce the peak-to-valley difference rate.

[0095] 4. Adjust the charging and discharging strategy of energy storage to reduce the peak-to-valley rate of the system.

[0096] To reduce the peak-to-valley difference rate of the source-grid-load-storage system, the charging and discharging strategy of energy storage is adjusted. It is necessary to first compare the load peak-to-valley difference rate with the interpolation of the system peak-to-valley difference rate when the energy storage does not participate in the peak-to-valley difference rate regulation, calculate the adjustment amount between the current peak-to-valley value and the target peak-to-valley value, and dynamically adjust the target peak-to-valley difference rate according to the real-time charge state and power limit of the energy storage during the actual regulation process of the energy storage, so as to explore the regulation capacity of the energy storage as much as possible, thereby achieving the goal of reducing the system peak-to-valley difference rate under the scenario of new energy output fluctuation. The specific methods are as follows:

[0097] (1) Compare the difference between load power consumption and renewable energy output at each moment, and based on this, modify the external power receiving characteristics of the source-grid-load-storage system, as follows. First, calculate the difference between power consumption and power generation at each moment:

[0098] P0=P L -P G

[0099] Where P0 is the difference between power consumption and power generation at each moment. For moment T, if P0(T)≤0, the load power consumption is less than the output of new energy, and the external power receiving characteristics of the source-grid-load-storage system can be made 0 by abandoning power. Therefore, for the moment when P0(T)≤0, no additional adjustment is required for the charging and discharging of energy storage, and P0(T)=0 can be made; if P0(T)>0 at moment T, it is necessary to purchase electricity from the public grid to meet the actual load demand, and the external power receiving characteristics at this time are P0(T). Therefore, the following corrections are made to P0 at each moment to obtain the actual external power receiving characteristics:

[0100]

[0101] Where P(T) is the external power receiving characteristic.

[0102] (2) If the natural peak-to-valley difference of the load is used as a reference value, the following adjustments are made to the peak-to-valley value:

[0103]

[0104] Where P min and P max are the valley and peak values ​​of the external power receiving characteristics, max{·} is the maximum value operator, P(T1), P(T2), ..., P(T 24 ) is the external power received at each time of the day, λ is the adjustment coefficient of the peak and valley values, P m ' in and P m ' ax They are the target valley value and peak value respectively. It is worth noting that in actual calculation, the target peak-to-valley difference rate can also be set by oneself instead of using the natural peak-to-valley difference rate of the load as the adjustment target.

[0105] (2) Based on the target peak and valley values, adjust the charging and discharging power of the energy storage at each moment. The specific method is as follows:

[0106] 1) For time T = 1, verify that P(T) < P m ' in Is it true? If so, go to step 2); if not, go to step 3);

[0107] 2) P(T)<P m ' in When the external power is less than the target valley value, the energy storage needs to be charged to increase the external power. The charging power of the energy storage is determined by the real-time state of charge SOC of the energy storage and the maximum charging power P of the energy storage. b.max , and at this time P m ' in -P(T), the charging power of energy storage is calculated by the following method:

[0108]

[0109] From the charging power of the energy storage, it can be inferred that the external power received by the source-grid-load-storage system at this time is:

[0110] P′(T)=P b (T)+P(T)

[0111] Since the energy storage charging power is affected by other limiting factors, it may not be able to fully supplement P m ' in -P(T), resulting in the external power receiving characteristic P′(T) after energy storage charging still being less than the target valley value P m ' in , at this time, the target peak and valley values ​​need to be updated accordingly to achieve the peak-to-valley difference rate adjustment target in subsequent adjustments:

[0112]

[0113] (3) If P(T)≥P m ' in , the external power is greater than the target valley value, verifying that P(T)<P m ' ax Is it established? If not, go to step 4). If it is established, then the external power received by the source-grid-load-storage system meets the requirements of the peak-valley range. The energy storage can be charged and discharged according to the charge state of the energy storage within the peak-valley range as a backup for subsequent adjustments. The principle of energy storage charging and discharging is: when the remaining power of the energy storage is less than the minimum charging and discharging power, the energy storage needs to be charged. The energy storage charging leads to an increase in electricity demand, and the increased electricity demand should not be greater than the target peak value P m' ax ; Charging power of energy storage; When the remaining chargeable capacity of energy storage is less than the minimum charge and discharge power, energy storage discharge is required. Energy storage discharge causes the external power to decrease. The external power after reduction should not be less than P m ' in , which can be calculated as:

[0114]

[0115] (4) If P(T)≥P m ' ax If the external power is greater than the target peak, the energy storage needs to be discharged to reduce the external power. The discharge power of the energy storage is determined by the real-time state of charge SOC of the energy storage and the maximum discharge power P of the energy storage. b.max , and at this time P(T)-P m ' ax The discharge power of energy storage is calculated by the following method:

[0116] P b (T) = -min{P b.max ,SOC×Q B ,P(T)-P m ' ax}

[0117] The external power P'(T) of the source-grid-load-storage system can be inferred from equation (1.9). Since the energy storage discharge power is affected by other limiting factors, it may not be able to fully supplement P(T)-P m ' ax The difference between the two causes the external power receiving characteristic P′(T) after the energy storage discharge to be still greater than the target peak value P m ' ax , at this time, the target peak and valley values ​​need to be updated accordingly to achieve the peak-to-valley difference rate adjustment target in subsequent adjustments:

[0118]

[0119] Since the adjustment directions of the target peak and valley values ​​are inconsistent due to different reasons, the operation of readjusting the target peak and valley values ​​due to the external power receiving characteristics after energy storage control not meeting the target peak or valley values ​​can only be implemented once within a planning cycle (usually one day). If the peak and valley values ​​have been adjusted due to one of the reasons in the cycle steps, the target peak and valley values ​​will no longer be adjusted due to another reason in the subsequent steps.

[0120] (5) Calculate the system state variables such as the external power supply and the energy storage charge state at time T, and set T = T + 1. If T ≤ 24, go to step (1). If T > 24, stop the calculation. At this time, the charge and discharge plan of the energy storage within one day is [Pb (1),P b (2),....,P b (twenty four)] T , the external power received is [P′(1),P′(2),....,P′(24)] T Based on this, the peak-to-valley difference rate f(P max ,P min )for:

[0121]

[0122] The charging and discharging and external power receiving characteristics of the energy storage calculated by the above method are shown in Table 3. The external power receiving characteristics of the system before and after the energy storage participates in the peak-valley rate regulation are shown in Table 3. Figure 2 As shown in the figure, it can be seen that the energy storage charging and discharging strategy proposed by the present invention can effectively reduce the peak-to-valley difference rate of the system. At this time, the peak-to-valley difference rate of the external power receiving characteristics of the system is It is equal to the natural peak-to-valley rate of the load, achieving the regulation goal.

[0123] Table 3 Typical daily operation data after adjusting the peak-to-valley difference rate (unit: MW)

[0124] time Wind power Photovoltaic Initial load Energy storage charging and discharging External power supply 0:00 43.22 0 134.570 7.59 99.34 1:00 36.35 0 138.045 0 102.08 2:00 16.08 0 140.265 0 124.58 3:00 11.64 0 143.748 0 132.50 4:00 15.01 0 148.041 0 133.43 5:00 29.2 0 152.334 0 123.52 6:00 32.35 0 150.702 0 118.74 7:00 43.35 0 156.010 0 113.06 8:00 68.57 35.26 166.621 36.56 99.34 9:00 37.15 83.07 169.537 50.03 99.34 10:00 19.28 90.49 172.453 36.66 99.34 11:00 3.79 58.93 175.369 0 112.64 12:00 0.24 76.82 178.528 0 101.46 13:00 0 12.52 181.687 -15.57 153.58 14:00 0 15.92 147.483 0 131.55 15:00 2.19 0 149.846 0 148.05 16:00 12.55 0 160.581 0 148.42 17:00 22.61 0 174.932 0 152.72 18:00 29.07 0 189.107 -6.84 153.58 19:00 32.28 0 204.001 -18.53 153.58 20:00 33 0 207.646 -21.45 153.58 21:00 31.96 0 208.051 -22.89 153.58 22:00 48.65 0 201.873 -0.02 153.58 23:00 46.28 0 201.731 -2.25 153.58

[0125] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the present invention should fall within the scope of the present invention.

Claims

1. A method for controlling energy storage for reducing the peak-to-valley difference rate of a source-grid-load-storage integrated system, characterized in that The steps include: Step 1: Forecast the output of new energy in a control cycle, calculate the natural peak-to-valley difference rate of the load, and obtain the new energy output curve and load characteristic curve; Step 2: Based on the new energy output curve and load characteristic curve in step 1, analyze and compare the natural peak-to-valley difference rate of the load in step 1 with the peak-to-valley difference rate when the energy storage charging and discharging strategy does not participate in the peak-to-valley difference rate regulation. If the natural peak-to-valley difference rate of the load satisfies the condition that it is greater than the peak-to-valley difference rate when the energy storage charging and discharging strategy does not participate in the peak-to-valley difference rate regulation, stop the calculation of the control cycle. If not, proceed to step 3. Step 3: Adjust the charging and discharging strategy of the energy storage with the goal of reducing the peak-to-valley rate of the system.

2. The energy storage control method for reducing the peak-to-valley difference rate of the source-grid-load-storage integrated system according to claim 1, characterized in that: The step three is specifically as follows: with the goal of reducing the peak-to-valley difference rate of the source-grid-load-storage system, the charging and discharging strategy of the energy storage is adjusted, the adjustment amount between the current peak-to-valley value and the target peak-to-valley value is calculated, and in the actual adjustment process of the energy storage, the target peak-to-valley difference rate is dynamically adjusted according to the real-time charge state and power limit of the energy storage, so as to explore the adjustment capacity of the energy storage as much as possible, thereby achieving the goal of reducing the peak-to-valley difference rate of the system under the scenario of new energy output fluctuation. The specific method is as follows: (1) Compare the difference between the load power consumption and the new energy output at each moment, and based on the difference, correct the external power receiving characteristics of the source-grid-load-storage system, as follows: First, calculate the difference between the power consumption and the power generation at each moment: P0=P L -P G (1.5) Where P L is the load demand, P G is the output of new energy, P0 is the difference between the power consumption and the power generation at each moment; for moment T, if P0(T)≤0, the load power consumption is less than the output of new energy, and the external power receiving characteristic of the source-grid-load-storage system can be made 0 by abandoning power. Therefore, for the moment when P0(T)≤0, no additional adjustment is required for the charging and discharging of energy storage, and P0(T)=0 can be made; if P0(T)>0 at moment T, it is necessary to purchase electricity from the public grid to meet the actual load demand, and the external power receiving characteristic at this time is P0(T); therefore, the following corrections are made to P0 at each moment to obtain the actual external power receiving characteristic: Where P(T) is the external power receiving characteristic; (2) If the natural peak-to-valley difference of the load is used as a reference value, the following adjustments are made to the peak-to-valley value: Where P min and P max are the valley and peak values ​​of the external power receiving characteristics, max{·} and min{·} are the operators of maximum and minimum values, P(T1), P(T2), ..., P(T 24 ) is the external power received at each time of the day, λ is the adjustment coefficient of the peak and valley values, P m ' in and P m ' ax are the target valley and peak values, respectively; (3) Based on the target peak and valley values, adjusting the charging and discharging power of the energy storage at each moment; comprising the following steps: 1) For time T = 1, verify that P(T) < P m ' in Is it true? If so, go to step 2); if not, go to step 3); 2) P(T)<P m ' in When the external power is less than the target valley value, the energy storage needs to be charged to increase the external power. The charging power of the energy storage is determined by the real-time state of charge SOC of the energy storage and the maximum charging power P of the energy storage. b.max , and at this time P m ' in -P(T), the charging power of energy storage is calculated by the following method: Where Pb(T) is the charging and discharging power of the energy storage at time T, P b.max is the limit of energy storage charging and discharging power, SOC is the real-time charge state of energy storage, Q B is the capacity of energy storage; From the charging power of the energy storage, it can be inferred that the external power received by the source-grid-load-storage system at this time is: P′(T)=P b (T)+P(T)(1.9) If the energy storage charging power cannot fully replenish P m ' in -P(T), resulting in the external power receiving characteristic P′(T) after energy storage charging still being less than the target valley value P m ' in , at this time, the target peak and valley values ​​need to be updated accordingly to achieve the peak-to-valley difference rate adjustment target in subsequent adjustments: Where g(P L ) is the natural peak-to-valley rate of load; 3) If P(T)≥P m ' in , the external power is greater than the target valley value, verifying that P(T)<P m ' ax Is it established? If not, go to step 4). If established, then the external power received by the source-grid-load-storage system meets the requirements of the peak-valley value range. The energy storage is charged and discharged according to the charge state of the energy storage within the peak-valley value range as a backup for subsequent adjustment. The principle of energy storage charging and discharging is: when the remaining power of the energy storage is less than the minimum charging and discharging power, the energy storage needs to be charged. The energy storage charging leads to an increase in power demand, and the increased power demand should not be greater than the target peak value P m ' ax When the remaining chargeable capacity of the energy storage is less than the minimum charge and discharge power, the energy storage needs to be discharged. The energy storage discharge causes the external power to be reduced. The reduced external power should not be less than P m ' in , which can be calculated as: 4) If P(T)≥P m ' ax If the external power is greater than the target peak, the energy storage needs to be discharged to reduce the external power. The discharge power of the energy storage is determined by the real-time state of charge SOC of the energy storage and the maximum discharge power P of the energy storage. b.max And at this time P(T)-P m ' ax The discharge power of energy storage is calculated by the following method: P b (T)=-min{P b.max ,SOC×Q B ,P(T)-P m ′ ax }(1.12) The external power P′(T) of the source-grid-load-storage system can be inferred from equation (1.9); if the energy storage discharge power cannot fully supplement P(T)-P m ' ax The difference between the two causes the external power receiving characteristic P′(T) after the energy storage discharge to be still greater than the target peak value P m ' ax , at this time, the target peak and valley values ​​need to be updated accordingly to achieve the peak-to-valley difference rate adjustment target in subsequent adjustments: 5) Calculate the system state variables such as external power receiving and energy storage charge state at time T, and set T = T + 1. If T ≤ 24, go to step 1). If T > 24, stop the calculation. At this time, the charge and discharge plan of energy storage within one day is [P b (1),P b (2),....,P b (twenty four)] T , the external power received is [P′(1),P′(2),....,P′(24)] T Based on this, the peak-to-valley difference rate f(P max ,P min )for:

3. The energy storage control method for reducing the peak-to-valley difference rate of the source-grid-load-storage integrated system according to claim 2 is characterized in that: For step 4), the operation of re-adjusting the target peak value and target valley value due to the fact that the external power receiving characteristics after energy storage control do not meet the target peak value or valley value can only be implemented once within a planned cycle, and the planned cycle is 24 hours. If the peak and valley values ​​have been adjusted due to one of the reasons in the cycle step, the target peak and valley values ​​will not be adjusted due to another reason in the subsequent steps.

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