阅读说明：本技术 大规模储能电站串容等效模型的建模与仿真方法及系统 (Modeling and simulation method and system for series-capacitance equivalent model of large-scale energy storage power station ) 是由 牛萌 刘璐 李蓓 李相俊 马会萌 修晓青 徐少华 闫涛 贾学翠 于 2021-01-26 设计创作，主要内容包括：本发明提供一种大规模储能电站串容等效模型的建模与仿真方法及系统,利用简单戴南模型与详细模型的端电压差值,等效计算电容值,对简单戴维南模型修正为串容等效模型,该模型在仿真时,基于电站实际成组结构,对电池进行加速老化实验,通过分析电池单体与成组外特性的关系,充分考虑电池串之间不均衡电流,利用创建的串容等效模型和成组后的并联方程组,实现了在更长时间尺度内提升建模的精确性。(The invention provides a modeling and simulation method and a system of a serial capacity equivalent model of a large-scale energy storage power station, wherein a capacitance value is equivalently calculated by utilizing a terminal voltage difference value of a simple wear south model and a detailed model, the simple wear south model is corrected into the serial capacity equivalent model, the model is used for carrying out an accelerated aging experiment on batteries based on an actual grouped structure of the power station during simulation, unbalanced current among battery strings is fully considered by analyzing the relation between single batteries and grouped external characteristics, and the accuracy of modeling is improved in a longer time scale by utilizing the created serial capacity equivalent model and a grouped parallel equation set.)

1. A modeling method for a series capacitance equivalent model of a large-scale energy storage power station is characterized by comprising the following steps:

acquiring a simple Vietnam wearing model and a detailed model of a plurality of batteries with different SOCs connected in series and equivalent battery string parameters;

respectively calculating the detailed model terminal voltage and the simple Vietnam model terminal voltage of the series batteries, and calculating a terminal voltage difference value;

according to the calculated terminal voltage difference value, the battery parameters and an equivalent capacitance calculation formula, expressing the terminal voltage difference value by capacitance voltage, and calculating the capacitance values of equivalent capacitances of the series batteries in different discharge periods;

and correcting the simple wear-on Winan model according to the capacitance values in different discharge periods, and taking the corrected model as a direct current side series capacitance equivalent model.

2. The large-scale energy storage power station string capacity equivalent modeling method according to claim 1, characterized in that the battery parameters include open-circuit voltage, ohmic internal resistance, polarization capacitance of each battery in the battery string, and maximum SOC, minimum SOC and equivalent SOC of all batteries in the battery string.

3. The large-scale energy storage power station series capacitance equivalent modeling method of claim 1, characterized in that the voltage difference values of different discharge periods are calculated:

ΔU＝βΔSOC

wherein β is a linear coefficient; Δ SOC is the equivalent SOC.

4. The large-scale energy storage power station series capacitance equivalent modeling method as claimed in claim 1, wherein the equivalent capacitance calculation formula of the ith series of battery series is as follows:

wherein, beta_iIs the linear coefficient of the ith battery string,the actual total capacity of the maximum SOC battery within the battery string,the actual total capacity of the minimum SOC battery in the battery string.

5. The large-scale energy storage power station series-capacitance equivalent modeling method of claim 2, characterized in that the simple WEIGAN model is modified according to capacitance values in different discharge periods, and comprises the following three stages:

the first stage, obtaining the minimum SOC value of all batteries in the battery string, judging whether reaching SOC_tIf not, the SOC is reached_tStopping discharging when the discharging cut-off condition is reached, and not calculating the capacitance value of the equivalent capacitor; if the capacitance value of the equivalent capacitor is reached, calculating the capacitance value of the equivalent capacitor, and keeping the parameter to continuously discharge to enter a second stage; the SOC_tThe turning point of the SOC-OCV curve of the single battery in the battery string is shown;

the second stage, judging whether the equivalent SOC reaches the SOC_tIf not, the capacitance value of the current equivalent capacitor is kept unchanged, and if the SOC is reached_tCalculating the capacitance value of the equivalent capacitor at the moment as a new capacitance value, and entering a third stage;

the third stage, obtaining the maximum SOC value of all batteries in the battery string, and judging whether the maximum SOC value reaches SOC_tIf the voltage difference value does not reach the SOC value, the capacitance value of the equivalent capacitor at the moment is calculated again to serve as a new capacitance value to calculate the voltage difference value, and if the voltage difference value does not reach the SOC value_tThe discharge is stopped when the discharge cutoff condition has been reached.

6. A simulation method for a series capacitance equivalent model of a large-scale energy storage power station is characterized in that the simulation of the series capacitance equivalent model established by the method of any one of the claims 1 to 5 comprises the following steps:

carrying out accelerated aging simulation on the plurality of parallel battery strings, and solving the current of each branch battery string according to a parallel equation;

calculating terminal voltage according to the current of the branch battery strings obtained by solving and the capacitance of the series capacitance equivalent model of each branch battery string;

and respectively carrying out curve fitting on the obtained terminal voltage of the serial capacitance equivalent model and the terminal voltage of the detailed model to obtain a simulation result.

7. The method for simulating the series-capacitance equivalent model of the large-scale energy storage power station as claimed in claim 6, wherein the parallel equations are expressed by the following equation sets:

wherein, U_OCV,iIs the open circuit voltage, R, of each cell in the cell string_iOhmic internal resistance, U, in the battery string_p,iIs the polarization voltage, Δ U, of the battery string_iAnd correcting the voltage for the serial capacitance in the serial capacitance equivalent model.

8. The simulation method of the large-scale energy storage power station serial capacity equivalent model as claimed in claim 6, wherein the curve fitting is performed between the terminal voltage of the serial capacity equivalent model and the terminal voltage of the detailed model, and the method comprises the following steps:

respectively performing curve fitting on the terminal voltage of the serial capacitance equivalent model and the terminal voltage of the detailed model according to simulation time;

acquiring terminal voltage fitting curves of the serial capacitance equivalent model and the detailed model in the same coordinate system at the same simulation time;

judging whether the two terminal voltage fitting curves are overlapped, if not, respectively calculating the curvatures of the two curves at the separation position; and calculating a curvature difference value, wherein if the curvature difference value is smaller than a preset threshold value, the simulation effect is good, and if the curvature difference value is larger than the preset threshold value, the simulation effect is poor.

9. A modeling system of a series capacitance equivalent model of a large-scale energy storage power station is characterized in that: comprises that

The system comprises a data acquisition module, a data acquisition module and a data processing module, wherein the data acquisition module is used for acquiring a simple wear-on-Vinan model and a detailed model of a plurality of batteries with different SOCs connected in series and equivalent battery string parameters;

the terminal voltage calculation module is used for calculating the detailed model terminal voltage and the simple Vietnam model terminal voltage of the series batteries and calculating a terminal voltage difference value;

the equivalent capacitance calculation module is used for representing the terminal voltage difference value by capacitance voltage according to the calculated terminal voltage difference value, battery parameters and an equivalent capacitance calculation formula, and calculating the capacitance values of equivalent capacitances of the series batteries in different discharge periods;

and the series capacitance equivalent model establishing module is used for correcting the simple wear-on Winan model according to the capacitance values in different discharge periods, and taking the corrected model as a direct current side series capacitance equivalent model.

10. A simulation system of a series capacitance equivalent model of a large-scale energy storage power station is characterized in that: simulating a serial capacity equivalent model established by the method of any one of the preceding claims 1 to 5, comprising:

the branch battery string current acquisition module is used for carrying out accelerated aging simulation tests on the plurality of parallel battery strings and solving the current of each branch battery string according to a parallel equation;

the terminal voltage calculation module is used for calculating the terminal voltage according to the current of the branch battery strings obtained by solving and the series capacity equivalent model of each branch battery string;

and the curve fitting module is used for respectively performing curve fitting on the obtained terminal voltage of the serial capacitance equivalent model and the terminal voltage of the detailed model to obtain a simulation result.

Technical Field

The invention relates to the technical field of power circuit modeling, in particular to a modeling and simulation method and system for a series capacitance equivalent model of a large-scale energy storage power station.

Background

At present, large-scale energy storage direct current side modeling is often simplified into an equivalent single battery model, and the parameter difference of an internal battery is ignored. In fact, due to the manufacturing process of the battery, inconsistency is reflected among the monomers in the energy storage power station, and along with the aggravation of the working process, the capacity of electrochemical energy storage accessed in the power grid is continuously increased, the influence on the power system is more obvious, and the establishment of an accurate energy storage system equivalent model becomes one of the problems to be solved urgently in the field of power system simulation. The model of the domestic and foreign energy storage system in the power system simulation software is simple, the direct current side model of the energy storage system is generally replaced by the direct current source, and the research for the electrochemical energy storage equivalent characteristic and the modeling thereof which are oriented to the large power grid simulation calculation requirement and are matched with the large-scale intermittent power supply is not provided.

At present, the battery pack is simulated by the scholars successively, but the scholars mainly focus on small-scale battery series-parallel connection experiments or battery group modeling with good consistency, and related research contents are still to be perfected. The accurate energy storage model can reflect the running condition of an actual power station, and especially has important research significance on the influence of inconsistent batteries on grouping characteristics in the scene of future power battery gradient recycling under complex working conditions.

Disclosure of Invention

According to the modeling and simulation method and system for the serial-capacitance equivalent model of the large-scale energy storage power station, terminal voltage difference values of the simple donnan model and the detailed model are used for equivalence to calculate capacitance values, the simple donnan model is corrected into the serial-capacitance equivalent model, when the model is used for simulating and carrying out an accelerated aging experiment on batteries based on an actual grouped structure of the power station, unbalanced current between battery strings is fully considered by analyzing the relation between single batteries and grouped external characteristics, and modeling accuracy is improved within a longer time scale by using the created serial-capacitance equivalent model and the grouped parallel equation set.

The invention provides a modeling method of a series capacitance equivalent model of a large-scale energy storage power station, which comprises the following steps:

s1, acquiring a simple Vietnam wearing model and a detailed model of a plurality of different SOC batteries connected in series and equivalent battery string parameters;

s2, calculating the detailed model terminal voltage and the simple Vietnam model terminal voltage of the series batteries respectively, and calculating a terminal voltage difference value;

s3, representing the terminal voltage difference value by capacitance voltage according to the calculated terminal voltage difference value, battery parameters and an equivalent capacitance calculation formula, and calculating the capacitance values of equivalent capacitances of the series batteries in different discharge periods;

and S4, correcting the simple wear-on-Wien model according to the capacitance values in different discharge periods, and taking the corrected model as a direct current side series capacitance equivalent model.

According to the modeling method of the large-scale energy storage power station series-capacitance equivalent model, the terminal voltage difference value is equivalently calculated into the capacitance voltage value in different discharge periods, the simple Wien model is corrected, and the direct current side series-capacitance equivalent model is obtained.

Preferably, the battery parameters include open-circuit voltage, ohmic internal resistance, polarization capacitance of each battery in the battery string, and maximum SOC, minimum SOC, and equivalent SOC of all batteries in the battery string.

In any of the above embodiments, it is preferable to calculate the voltage difference for different discharge periods:

preferably, in any one of the above embodiments, the equivalent capacitance calculation formula is:

wherein, beta_iAs linear coefficient, Q1_iActual total capacity of the maximum SOC battery in the battery string, Q2_iThe actual total capacity of the minimum SOC battery in the battery string.

In any of the above embodiments, preferably, the correction of the simple wearvillan model according to the capacitance values of different discharge periods includes the following three stages:

the first stage, obtaining the minimum SOC value of all batteries in the battery string, judging whether reaching SOC_tIf not, the SOC is reached_tStopping discharging when the discharging cut-off condition is reached, and not calculating the capacitance value of the equivalent capacitor; if the capacitance value of the equivalent capacitor is reached, calculating the capacitance value of the equivalent capacitor, and keeping the parameter to continuously discharge to enter a second stage; the SOC_tThe turning point of the SOC-OCV curve of the single battery in the battery string is shown;

the second stage, judging whether the equivalent SOC reaches the SOC_tIf not, the capacitance value of the current equivalent capacitor is kept unchanged, and if the SOC is reached_tCalculating the capacitance value of the equivalent capacitor at the moment as a new capacitance value, and entering a third stage;

the third stage, obtaining the maximum SOC value of all batteries in the battery string, and judging whether the maximum SOC value reaches SOC_tIf the voltage difference value does not reach the SOC value, the capacitance value of the equivalent capacitor at the moment is calculated again to serve as a new capacitance value to calculate the voltage difference value, and if the voltage difference value does not reach the SOC value_tThe discharge is stopped when the discharge cutoff condition has been reached.

According to the modeling method of the large-scale energy storage power station series-capacitance equivalent model, when the simple Withanian model is corrected according to the capacitance values in different discharging periods, discharging characteristics in different discharging periods are fully considered, SOC and battery capacity are in positive correlation, the terminal voltage difference value is a piecewise linear function of time in the later discharging period, the capacitance is calculated according to different discharging time, perfect fitting of simulated terminal voltage and real voltage is achieved, the real discharging condition can be reflected, SOCmin parameters exist in the model, a single body causing discharging cutoff is conveniently judged, and balancing management of a BMS is facilitated.

The invention also provides a simulation method of the series capacitance equivalent model of the large-scale energy storage power station, which simulates the series capacitance equivalent model and comprises the following steps:

carrying out an accelerated aging simulation test on the plurality of parallel battery strings, and solving the current of each branch battery string according to a parallel equation;

calculating terminal voltage according to the current of the branch battery strings obtained by solving and the series capacity equivalent model of each branch battery string;

and respectively carrying out curve fitting on the obtained terminal voltage of the serial capacitance equivalent model and the terminal voltage of the detailed model to obtain a simulation result.

Preferably, the parallel equation is expressed by the following equation system:

wherein, U_OCV,iIs the open circuit voltage, R, of each cell in the cell string_iOhmic internal resistance, U, in the battery string_p,iIs the polarization voltage, Δ U, of the battery string_iAnd correcting the voltage for the serial capacitance in the serial capacitance equivalent model.

According to the simulation method of the series-capacitance equivalent model, the current of each branch battery string is solved according to the parallel equation, and the voltage is obtained by inputting the current by using the established series-capacitance equivalent model. The simulation result accords with the actual situation, the more detailed model can reduce the number of identification parameters required by modeling, and the simpler equivalent model can improve the modeling precision.

Further preferably, when comparing the terminal voltage of the serial capacity equivalent model with the terminal voltage of the detailed model, the method includes the following steps:

respectively performing curve fitting on the terminal voltage of the serial capacitance equivalent model and the terminal voltage of the detailed model according to simulation time;

acquiring terminal voltage fitting curves of the serial capacitance equivalent model and the detailed model in the same coordinate system at the same simulation time;

judging whether the two terminal voltage fitting curves are overlapped, if not, respectively calculating the curvatures of the two curves at the separation position; and calculating a curvature difference value, wherein if the curvature difference value is smaller than a preset threshold value, the simulation effect is good, and if the curvature difference value is larger than the preset threshold value, the simulation effect is poor.

The invention also provides a modeling system of the series capacitance equivalent model of the large-scale energy storage power station, which comprises

The system comprises a data acquisition module, a data acquisition module and a data processing module, wherein the data acquisition module is used for acquiring a simple wear-on-Vinan model and a detailed model of a plurality of batteries with different SOCs connected in series and equivalent battery string parameters;

the terminal voltage calculation module is used for calculating the detailed model terminal voltage and the simple Vietnam model terminal voltage of the series batteries and calculating a terminal voltage difference value;

the equivalent capacitance calculation module is used for representing the terminal voltage difference value by capacitance voltage according to the calculated terminal voltage difference value, battery parameters and an equivalent capacitance calculation formula, and calculating the capacitance values of equivalent capacitances of the series batteries in different discharge periods;

and the series capacitance equivalent model establishing module is used for correcting the simple wear-on Winan model according to the capacitance values in different discharge periods, and taking the corrected model as a direct current side series capacitance equivalent model.

The invention also provides a simulation system of the series capacitance equivalent model of the large-scale energy storage power station, which simulates the series capacitance equivalent model and comprises the following steps:

the branch battery string current acquisition module is used for carrying out accelerated aging simulation tests on the plurality of parallel battery strings and solving the current of each branch battery string according to a parallel equation;

the terminal voltage calculation module is used for calculating the terminal voltage according to the current of the branch battery strings obtained by solving and the series capacity equivalent model of each branch battery string;

and the curve fitting module is used for respectively performing curve fitting on the obtained terminal voltage of the serial capacitance equivalent model and the terminal voltage of the detailed model to obtain a simulation result.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a flow chart of a modeling method of a series capacitance equivalent model of a large-scale energy storage power station provided by the invention;

FIG. 2 is a flow chart of a simulation method of a series capacitance equivalent model of a large-scale energy storage power station provided by the invention;

FIG. 3 is a structural diagram of a modeling system of a series capacitance equivalent model of a large-scale energy storage power station provided by the invention;

FIG. 4 is a structural diagram of a simulation system of a series capacitance equivalent model of a large-scale energy storage power station provided by the invention;

FIG. 5 is a graph of voltage differences between a detailed model and a simple model in the background art of the present invention;

FIG. 6(a) is a schematic diagram of a model of the simple WEIGAN model of the present invention;

fig. 6(b) is a schematic model diagram of a series capacitance equivalent model of a large-scale energy storage power station provided by the invention;

FIG. 7 is a flow chart of modeling of a large-scale energy storage power station series capacitance equivalent model provided in an embodiment of the present invention;

fig. 8(a) is a comparison of terminal voltages of an equivalent model and a detailed model in a simulation process of a large-scale energy storage power station series capacitance equivalent model provided in an embodiment of the present invention;

fig. 8(b) shows SOC of a cell and an equivalent battery in a simulation process of the series capacitance equivalent model of the large-scale energy storage power station provided in the embodiment of the present invention;

FIG. 9 is a graph comparing terminal voltages of equivalent model and detailed model under the condition of multi-battery parallel current variation;

fig. 10 shows a voltage comparison of parallel equivalent model and detailed model.

Detailed Description

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

The following detailed description is exemplary in nature and is intended to provide further details of the invention. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention.

Interpretation of related art terms

First-order donning the vernan model: as shown in fig. 6(a), an equivalent circuit model of a battery is composed of an open-circuit voltage, an ohmic internal resistance and a first-order polarization RC circuit, a formula of terminal voltage is obtained as formula 1, and an ampere-hour integration method is adopted for a battery SOC;

SOH: the state of health state of the battery is the ratio of the maximum capacity of the battery in the current state to the rated capacity of the battery

SOC: the state of charge of the battery is the ratio of the current residual capacity of the battery to the current maximum capacity of the battery

BMS: battery management system.

As shown in fig. 1, the invention provides a modeling method of a series capacitance equivalent model of a large-scale energy storage power station, which comprises the following steps:

s1, obtaining a plurality of simple Vietnam wearing models with different SOC batteries connected in series and battery string parameters;

s2, calculating the detailed model terminal voltage and the simple Vietnam model terminal voltage of the series batteries respectively, and calculating a terminal voltage difference value;

s3, representing the terminal voltage difference value by capacitance voltage according to the calculated terminal voltage difference value, battery parameters and an equivalent capacitance calculation formula, and calculating the capacitance values of equivalent capacitances of the series batteries in different discharge periods;

and S4, correcting the simple wear-on-Wien model according to the capacitance values in different discharge periods, and taking the corrected model as a direct current side series capacitance equivalent model.

When the model is designed, two batteries are connected in series, a simple wear-on Winan model and a detailed model are respectively established, simulation results are shown in figure 1, in the series connection and grouping discharging process of the batteries with different SOC, the change trend of the open-circuit voltage difference and the voltage difference of the battery terminals is the same, and the difference of the polarization voltage and the ohmic voltage drop is relatively stable and can be ignored. The polarization voltage is rapidly increased at the end of discharge and becomes a main factor influencing the terminal voltage, the modeling accuracy at the end of discharge requires high data acquisition degree, and a general energy storage power station does not use the area, so the modeling neglects the area.

As can be seen from fig. 5, the voltage difference curves of the detailed model and the simple equivalent model have obvious inflection points at the later stage of discharge, and the voltage difference inflection points can be estimated according to the inflection point time to respectively correspond to the inflection points of the SOC-OCV curve of the battery and the equivalent battery in the series battery pack, that is, the SOC is the SOC_tThe time point of (a); the SOC_tIs the turning point of the SOC-OCV curve of the single batteries in the battery string. In combination with the above conclusion that the internal voltage difference of the detailed series battery modeling mainly comes from the difference of the SOC of each battery model in the detailed battery model, it can be concluded that the difference of the terminal voltage of the detailed battery model and the terminal voltage of the simple equivalent WEAVA model is also caused by the difference of the SOC of each battery, the SOC is positively correlated with the battery capacity, the delta SOC is a constant at constant current, the delta U is a piecewise linear function of time at the later stage of discharge, a correlation coefficient beta exists between the delta SOC and the delta U, so that the delta SOC and the delta U have the following relationship

The expression is consistent with the form of a capacitance characteristic equation, and a capacitor can be connected in series to offset the terminal voltage difference between a detailed model and a simple equivalent Withanan model, and the connected capacitance value isDue to the endThe voltage difference curve has a plurality of inflection points, and the value of the capacitance changes accordingly. The established series capacitance equivalent circuit model is shown in fig. 6, so the equivalent capacitance calculation formula is:

wherein, beta_iAs linear coefficient, Q1_iActual total capacity Q2 for maximum SOC in battery string_iThe actual total capacity of the minimum SOC battery in the battery string.

U in the figure_ocv，pack、R_pack、R_p，pack、C_p，packRepresenting the open-circuit voltage, the ohmic internal resistance, the polarization internal resistance and the polarization capacitance of the series equivalent model; u shape_ocv、R_i、R_p,i、C_p,iAnd the open-circuit voltage, the ohmic internal resistance, the polarization internal resistance and the polarization capacitance of each battery in the battery string are represented. SOC_max、SOC_min、SOC_equThe maximum SOC, the minimum SOC and the SOC of the equivalent model in the battery string are represented respectively, and the series capacitance correction voltage on the series capacitor is recorded as delta U.

The battery parameters comprise open-circuit voltage, ohmic internal resistance, polarization capacitance of each battery in the battery string, and maximum SOC, minimum SOC and equivalent SOC of all batteries in the battery string.

In any of the above embodiments, preferably, the correction of the simple wearvillan model according to the capacitance values of different discharge periods includes the following three stages:

the first stage, obtaining the minimum SOC value of all batteries in the battery string, judging whether reaching SOC_tIf not, the SOC is reached_tStopping discharging when the discharging cut-off condition is reached, and not calculating the capacitance value of the equivalent capacitor; if the capacitance value of the equivalent capacitor is reached, calculating the capacitance value of the equivalent capacitor, and keeping the parameter to continuously discharge to enter a second stage; the SOC_tThe turning point of the SOC-OCV curve of the single battery in the battery string is provided by a manufacturer;

the second stage, judging whether the equivalent SOC reaches the SOC_tIf, ifIf not, the capacitance value of the current equivalent capacitor is kept unchanged, and if the SOC is reached_tCalculating the capacitance value of the equivalent capacitor at the moment as a new capacitance value, and entering a third stage;

the third stage, obtaining the maximum SOC value of all batteries in the battery string, and judging whether the maximum SOC value reaches SOC_tIf the voltage difference value does not reach the SOC value, the capacitance value of the equivalent capacitor at the moment is calculated again to serve as a new capacitance value to calculate the voltage difference value, and if the voltage difference value does not reach the SOC value_tThe discharge is stopped when the discharge cutoff condition has been reached.

As shown in FIG. 7, a detailed model and a simple Thevenin equivalent model are first established for the battery string, and the lowest SOC in the detailed model battery string reaches SOCSOC_tMeanwhile, the series capacitance value is calculated through the voltage difference, the parameter is kept to be simulated continuously, and if the SOC of the equivalent series model does not reach the SOC_tStopping simulation when the discharge cutoff condition is reached, and stopping simulation if the equivalent series model SOC reaches the SOC_tUpdating the capacitance value to continue simulation, and if the SOC is not reached at the highest SOC_tIf the discharge cutoff condition is reached, the simulation is stopped, and if the discharge cutoff condition is reached, the capacitance value is updated again.

As shown in fig. 8, lithium iron phosphate batteries are connected in series to perform an accelerated decline experiment to obtain a capacity attenuation parameter of a single battery in a battery string, two single batteries with different SOHs and SOCs of 0.9 and 0.5 respectively are selected to perform series simulation, and a simulation result is as shown in fig. 8(a) and 8(b), when 1C discharges, a series capacitance equivalent model greatly reduces a terminal voltage difference value between the series capacitance equivalent model and a detailed model, and the accuracy of equivalent modeling is improved. And correcting the capacitance value according to the voltage difference value when the SOC of each battery reaches 35%.

The battery string model can be popularized on the basis, the voltage difference curve of the battery string detailed model and the simple equivalent model which are connected in series with a plurality of batteries also has an obvious inflection point at the later discharging stage, and the time nodes for changing the capacitance are set as the time when SOCmax, SOCmin and SOCequ respectively reach the inflection point of the SOC-OCV curve. And (5) carrying out variable current working condition simulation, wherein as shown in fig. 9, the series capacitance model can better fit the terminal voltage of the detailed model.

As shown in fig. 2, the present invention further provides a simulation method for a serial capacitance equivalent model of a large-scale energy storage power station, which simulates the serial capacitance equivalent model, and includes:

carrying out an accelerated aging simulation test on the plurality of parallel battery strings, and solving the current of each branch battery string according to a parallel equation;

calculating terminal voltage according to the current of the branch battery strings obtained by solving and the series capacity equivalent model of each branch battery string;

and comparing the obtained terminal voltage of the serial capacitance equivalent model with the terminal voltage of the detailed model to obtain a simulation effect.

Preferably, the parallel equation is expressed by the following equation system:

wherein, U_OCV,iIs the open circuit voltage, R, of each cell in the cell string_iOhmic internal resistance, U, in the battery string_p,i is the polarization voltage of the battery string, and Δ U is the string capacitance correction voltage in the string capacitance equivalent model.

Further preferably, when comparing the terminal voltage of the serial capacity equivalent model with the terminal voltage of the detailed model, the method includes the following steps:

respectively performing curve fitting on the terminal voltage of the serial capacitance equivalent model and the terminal voltage of the detailed model according to simulation time;

acquiring terminal voltage fitting curves of the serial capacitance equivalent model and the detailed model in the same coordinate system at the same simulation time;

judging whether the two terminal voltage fitting curves are overlapped, and if the two terminal voltage fitting curves are not overlapped, respectively calculating the curvatures of the two curves at the separation position; and calculating a curvature difference value, wherein if the curvature difference value is smaller than a preset threshold value, the simulation effect is good, and if the curvature difference value is larger than the preset threshold value, the simulation effect is poor.

As shown in fig. 10, a battery string formed by connecting seven lithium iron phosphate batteries of the same type in series is used for an accelerated aging test, and the difference parameter of the SOH inside n battery strings with different degradation degrees is defined as

Selecting an SOH parameter building model of seven batteries under six time nodes for parallel simulation, wherein a parallel equation considering ohmic drop, polarization voltage, open-circuit voltage and series capacitance correction voltage is as follows:

and after the processing, a solution equation set of the branch current can be obtained.

According to the midway curve, the terminal voltage curve of the serial capacitance equivalent model is most close to the detailed model, the calculation amount is less compared with the detailed model, and the terminal voltage curve can be more fit to the actual situation compared with the method that the terminal voltage curve is simply worn by a Wien model.

According to the invention, the capacitor is connected in series in the simple series equivalent circuit, so that under the condition of correcting the series connection of two batteries, the open-circuit voltage difference part caused by different SOC (system on chip) in the voltage difference between the simple equivalent model and the detailed model is deduced to the multi-battery series connection situation in the same way, and the model is still suitable. Work and the simulated computation volume are discerned to the loaded down with trivial details parameter that this model more detailed model significantly reduced, and the precision that battery string was modelled can be promoted to simpler equivalent model, and has SOCmin parameter in the model, conveniently judges to cause the monomer that discharges and end, does benefit to BMS's balanced management. Under the condition that the battery series-parallel connection meets the actual power station capacity requirement, the accuracy of the model can still be improved.

As shown in FIG. 3, the invention also provides a modeling system of the series capacitance equivalent model of the large-scale energy storage power station, which comprises

The system comprises a data acquisition module, a data acquisition module and a data processing module, wherein the data acquisition module is used for acquiring a simple wear-on-Vinan model and a detailed model of a plurality of batteries with different SOCs connected in series and equivalent battery string parameters;

the terminal voltage calculation module is used for calculating the detailed model terminal voltage and the simple Vietnam model terminal voltage of the series batteries and calculating a terminal voltage difference value;

the equivalent capacitance calculation module is used for representing the terminal voltage difference value by capacitance voltage according to the calculated terminal voltage difference value, battery parameters and an equivalent capacitance calculation formula, and calculating the capacitance values of equivalent capacitances of the series batteries in different discharge periods;

and the series capacitance equivalent model establishing module is used for correcting the simple wear-on Winan model according to the capacitance values in different discharge periods, and taking the corrected model as a direct current side series capacitance equivalent model. The system is used for implementing the modeling method of the series capacitance equivalent model of the large-scale energy storage power station, the specific implementation process is shown in the method, and the detailed description is omitted here.

As shown in fig. 4, the present invention further provides a simulation system for a serial capacitance equivalent model of a large-scale energy storage power station, which simulates the serial capacitance equivalent model, and includes:

carrying out an accelerated aging simulation test on the plurality of parallel battery strings, and solving the current of each branch battery string according to a parallel equation;

calculating terminal voltage according to the current of the branch battery strings obtained by solving and the series capacity equivalent model of each branch battery string;

and comparing the obtained terminal voltage of the serial capacitance equivalent model with the terminal voltage of the detailed model to obtain a simulation effect. The system is used for implementing the simulation method of the series capacitance equivalent model of the large-scale energy storage power station, and the specific implementation process is shown in the method and is not described herein again.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be appreciated by those skilled in the art that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed above are therefore to be considered in all respects as illustrative and not restrictive. All changes which come within the scope of or equivalence to the invention are intended to be embraced therein.