CN107046294A - Combined energy storage capacity allocation method based on probability and statistics - Google Patents

Abstract

The invention discloses a method for configuring combined energy storage capacity based on probability statistics. The method comprises the following steps: first counting the charging demand and the discharging demand, calculating the capacity interval where each charge and discharge demand is located, sorting the capacity intervals according to the number of charge and discharge demands in each capacity interval, and determining the reference rated capacity according to the maximum value of the capacity interval, If the combination of small capacity in the reference rated capacity is within the threshold range of large capacity, the combination of small capacity will replace the large capacity to obtain the combined energy storage capacity; then calculate its occurrence probability according to the duration of each power reference value, and then based on the combined capacity and confidence level to get the power of each combined energy storage. The invention can solve the configuration problem of energy storage modular combination in actual engineering, and is beneficial to the efficient operation of the energy storage system.

Description

Combined energy storage capacity allocation method based on probability and statistics

technical field

The invention relates to a method for configuring combined energy storage capacity, in particular to a method for optimally configuring combined energy storage capacity based on probability statistics.

Background technique

Energy storage systems can smooth load fluctuations through charging and discharging, which makes them widely used in power system generation, distribution and consumption. On the power generation side, the lack of traditional energy sources promotes the rapid development of new energy sources, while new energy generation based on wind and solar energy is volatile and intermittent, and its large-scale grid connection will affect the safe and stable operation of the grid. Apps largely solve this problem. On the power consumption side, the increase in load peaks in the power grid will increase the investment in power transmission and distribution equipment, thereby reducing the equipment utilization rate of the power system. The investment in large-scale energy storage systems is an effective way to upgrade and transform traditional power grids. However, due to the high cost of energy storage systems today, excessively large energy storage will lead to high system investment costs, and too small energy storage will not guarantee the stabilization effect. Therefore, a reasonable allocation of energy storage capacity is particularly important.

In the existing studies on the optimal configuration of energy storage system capacity, most of them take the total capacity of energy storage as the optimization variable. However, in actual engineering, energy storage equipment has capacity limitations. Energy storage systems are generally composed of multiple energy storage modules. Choosing different capacity combinations will result in different system economics. Therefore, how to use different storage modules? The reasonable combination of energy modules to achieve the economical and efficient utilization of the system is worth discussing, but there is a gap in the current research in this area.

Contents of the invention

In order to solve the capacity optimization problem of combined energy storage due to the capacity limitation of energy storage equipment, the present invention provides a combined energy storage capacity optimization method, which can not only calculate the capacity and power of combined energy storage, but also make the system economical Sex is better.

A combined energy storage capacity configuration method based on economic analysis, the method includes the following steps.

1) Obtain the minimum rated total capacity and total power of the energy storage system according to the load demand:

During the time period T starting from time t ₀ , for the energy storage load PL , the maximum discharge energy E _d that needs to be provided by the energy storage system and the maximum charge energy E _c that _needs to be absorbed by the energy storage system are:

Furthermore, the corresponding rated total capacity of the energy storage system is:

In the formula, is the discharge efficiency of the energy storage system, For the charging efficiency of the energy storage system, is the efficiency of the converter, S _max and S _min are the upper and lower limits of the state of charge of the energy storage system, respectively;

Similarly, the rated power of the energy storage system needs to meet the maximum power deficit P _c and the maximum excess power P _d of the energy storage load, so the total rated power P _R is:

.

2) Look for the switching position of charging and discharging _: For the historical data of energy storage load, within the time period T starting from time t0 , record the switching time t _cs from charging to discharging and the switching time t _ds from discharging to charging, and record a total of I time points .

3) According to the switching position, calculate the charging demand Q _c and discharging demand Q _d in different switching time periods, the calculation formula is as follows:

.

4) Divide the total energy storage capacity E _R into n parts on average, and the capacity of each part is , construct n capacity intervals R _i : .

5) Calculate the capacity interval where each charge and discharge demand is located, count the number of charge and discharge demands in each interval, sort each capacity interval R _i according to the number, and obtain the sequence of capacity intervals with the number of charge and discharge demands from large to small .

6) Take the maximum value in the capacity interval as the minimum charge and discharge energy e of the combined energy storage, in order to keep the energy storage in a good charge and discharge state, set the operating charge and discharge depth d _r to 0.7, then the reference rated capacity e of the combined battery _R is: e _R = e / d _r ; then the reference rated capacity sequence is obtained from the capacity interval sequence S .

7) Set the threshold k and judge Is it possible to If possible, replace the original rated capacity e _{R i} with the combination to obtain the combined energy storage capacity E ^' .

8) Calculate the quantity of energy storage in each combination: allocate the quantity of batteries according to the probability of occurrence of loads similar to the reference rated capacity e _R , the greater the probability, the larger the quantity, and the total capacity of all energy storage systems is equal to the minimum rated total capacity E _R of the energy storage system.

9) Construct reference power vector , the statistics are in the time period of P _{r i} duration time t _{r i} in the historical data, then its occurrence probability for: .

10) For the elements E _{c i} in the maximum combined energy storage capacity E ^' , the statistics The corresponding maximum power value P _{c i} ^' in the historical data.

11) Set the letter level to , requiring rated power at confidence level To meet the demand of load power, according to P _{c i} ^' corresponding right make adjustments, bigger The larger the value is, the rated power P _{c i} corresponding to E _{c i} is determined.

The beneficial effect of the present invention is that a highly economical combined energy storage configuration method can be obtained to realize efficient configuration of combined energy storage, and the optimization strategy is simple and easy to implement.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a block diagram of a method for determining combined capacity and power of energy storage based on probability and statistics.

Figure 2 is a load power diagram.

Figure 3 is a diagram of the battery combination results.

detailed description

In order to make the purpose, technical solution and advantages of the present invention clearer, the implementation manners of the present invention will be further described in detail below.

1) Obtain the minimum rated total capacity and total power of the energy storage system according to the load demand:

During the time period T starting from time t ₀ , for the energy storage load PL , the maximum discharge energy E _d that needs to be provided by the energy storage system and the maximum charge energy E _c that _needs to be absorbed by the energy storage system are:

Furthermore, the corresponding rated total capacity of the energy storage system is:

In the formula, is the discharge efficiency of the energy storage system, For the charging efficiency of the energy storage system, is the efficiency of the converter, S _max and S _min are the upper and lower limits of the state of charge of the energy storage system, respectively;

Similarly, the rated power of the energy storage system needs to meet the maximum power deficit P _c and the maximum excess power P _d of the energy storage load, so the total rated power P _R is:

.

2) Look for the switching position of charging and discharging _: For the historical data of energy storage load, within the time period T starting from time t0 , record the switching time t _cs from charging to discharging and the switching time t _ds from discharging to charging, and record a total of I time points .

3) According to the switching position, calculate the charging demand Q _c and discharging demand Q _d in different switching time periods, the calculation formula is as follows:

.

4) Divide the total energy storage capacity E _R into n parts on average, and the capacity of each part is , construct n capacity intervals R _i : .

5) Calculate the capacity interval where each charge and discharge demand is located, count the number of charge and discharge demands in each interval, sort each capacity interval R _i according to the number, and obtain the sequence of capacity intervals with the number of charge and discharge demands from large to small .

6) Take the maximum value in the capacity interval as the minimum charge and discharge energy e of the combined energy storage, in order to keep the energy storage in a good charge and discharge state, set the operating charge and discharge depth d _r to 0.7, then the reference rated capacity e of the combined battery _R is: e _R = e / d _r . Then the reference rated capacity sequence is obtained from the capacity interval sequence S .

7) Set the threshold k and judge Is it possible to If possible, replace the original rated capacity e _{R i} with the combination to obtain the combined energy storage capacity E ^' .

8) Calculate the quantity of energy storage in each combination: allocate the quantity of batteries according to the probability of occurrence of loads similar to the reference rated capacity e _R , the greater the probability, the larger the quantity, and the total capacity of all energy storage systems is equal to the minimum rated total capacity E _R of the energy storage system.

9) Construct reference power vector , the statistics are in the time period of P _{r i} duration time t _{r i} in the historical data, then its occurrence probability for: .

10) For the elements E _{c i} in the maximum combined energy storage capacity E ^' , the statistics The corresponding maximum power value P _{c i} ^' in the historical data.

11) Set the letter level to , requiring rated power at confidence level To meet the demand of load power, according to P _{c i} ^' corresponding right make adjustments, bigger The larger the value is, the rated power P _{c i} corresponding to E _{c i} is determined.

The block diagram of energy storage combination capacity and capacity determination algorithm is shown in Figure 1.

Taking the actual year's load data in a region as an example, it is assumed that within the operating life of the energy storage, the load change is consistent with that year.

According to the proposed method, a total of 1024 battery combinations are obtained through simulation, and the optimal combination is selected according to the economy among these 1024 kinds. The optimization results are shown in Figure 3, where the capacity, power and the number of each type of battery are shown in the figure.

Claims (4)

1. a kind of combined accumulation energy capacity collocation method based on probability statistics, it is characterised in that the described method comprises the following steps：

1) charge requirement of statistics energy storage load and electric discharge demand；The specified total capacity of energy storage is divided equally to interval to build capacity, and Capacity where calculating each charge-discharge power demand is interval；Capacity interval is sorted according to charge-discharge power demand number in each capacity interval, Determine to refer to rated capacity further according to each interval inner capacities maximum after sequence；If with reference to the combination of rated capacity Small And Medium Capacity In the threshold range of Large Copacity, then the combination of low capacity is replaced into Large Copacity, obtain combined accumulation energy capacity；Then according to total appearance The probability that size and the close charge-discharge power demand of bank capability occur is measured, the quantity of each combined accumulation energy is obtained；

2) nominal total power is divided equally and obtains value and power reference, according to duration of each value and power reference in load, calculate Its probability of occurrence；Capacity again based on combined accumulation energy and the confidence level changed with probability of occurrence, calculate each combined accumulation energy Power.

2. a kind of combined accumulation energy capacity collocation method based on probability statistics according to claim 1, it is characterised in that meter Calculating the specific method of the specified total capacity of energy storage and nominal total power is：

Fromt ₀What the moment startedTIn period, for energy storage loadP _L, it is necessary to the maximum discharge energy that energy-storage system is providedE _dWith The maximum charge energy for needing energy-storage system to absorbE _cFor：

And then, the corresponding specified total capacity of energy-storage system is：

In formula,For the discharging efficiency of energy-storage system,For the charge efficiency of energy-storage system,For the efficiency of current transformer,S _max WithS _minRespectively energy-storage system state-of-charge upper and lower limit；

Similarly, the rated power of energy-storage system needs to meet the peak power vacancy of energy storage loadP _cWith maximum excess powerP _d, because This nominal total powerP _RFor：

。

3. a kind of combined accumulation energy capacity collocation method based on probability statistics according to claim 1, it is characterised in that meter Calculate comprising the concrete steps that for combined accumulation energy rated capacity：

1) discharge and recharge switching position is found：For the historical data of energy storage load, fromt ₀Moment startsTIn period, record charging To the time of electric discharge switchingt _csThe time switched with electric discharge to chargingt _ds, record altogetherIIndividual time point；

2) according to switching position, the charge requirement of different switching time sections is calculatedQ _cWith electric discharge demandQ _d, calculation formula is as follows：

3) by energy storage total capacityE _RIt is divided intonPart, it is per a capacity, buildnIndividual capacity is intervalR _i ： ；

4) capacity where calculating each charge-discharge power demand is interval, the number of each interval interior charge-discharge power demand is counted, according to number pair Each capacity is intervalR _i It is ranked up, obtains the capacity sequence of intervals of charge-discharge power demand number from big to small；

5) the minimum charge-discharge energy of combined accumulation energy is used as using the maximum in capacity intervale, preferably filled to be in energy storage Discharge condition, sets operation depth of discharged _rFor 0.7, then the reference rated capacity of assembled batterye _RFor：e _R=e/d _r；Then by holding Measure sequence of intervalsSObtain referring to rated capacity sequence；

6) threshold value is setk, judgeWhether can be byCombine, if can be with, It will combine former rated capacitye _Ri Instead of obtaining combined accumulation energy capacityE ^’；

7) quantity of each combined accumulation energy is calculated：According to referring to rated capacitye _RThe number for the probability assignments battery that close load occurs Amount, the bigger quantity of probability is bigger, and all energy storage total capacities are equal to the minimum specified total capacity of energy-storage systemE _R。

4. a kind of combined accumulation energy capacity collocation method based on probability statistics according to claim 1, it is characterised in that meter The rated power for calculating combined accumulation energy is comprised the concrete steps that：

1) reference power vector is built, statistics be in the time cycleHistory In dataP _ri Durationt _ri , then its probability of occurrenceFor：；

2) for most combined accumulation energy capacityE ^’In elementE _ci , statisticsIt is corresponding in the historical data Maximum power valueP _ci ^’；

3) set confidence level as, it is desirable to rated power is in confidence levelThe lower demand for meeting load power, according toP _ci ^’Correspondence 'sIt is rightIt is adjusted,It is biggerIt is bigger, it is determined thatE _ci Corresponding rated powerP _ci 。