CN104134829B - Storage battery energy storage system control method - Google Patents

Abstract

The invention relates to a storage battery energy storage system control method which is technically characterized in that: reading the state of charge Soc (T) of current moment of a storage battery; according to a load forecasting result of the system in the next period of time delta t, estimating the exchange power Pex of the storage battery and the external within Delta t; according to the operating voltage of the storage battery system, calculating the exchange current Iex = Pex / U of the storage battery and the external within Delta t; if the exchange current Iex > 0, namely the storage battery is in discharging, performing the storage battery dischargeing control process, otherwise performing the storage battery charging control process. The storage battery energy storage system control method is reasonable in design, according to the electric quantity change situations in the storage battery in different charge and discharge current situations, optimization of the management and control of the storage battery energy storage system can be implemented, the energy conversion efficiency of the storage battery energy storage system can be effectively improved, the storage battery energy storage system control method can be widely used for energy management and control of energy storing devices of electric vehicle charging stations, micro networks or UPS systems.

Description

A method for controlling a battery energy storage system

technical field

The invention belongs to the technical field of storage battery energy storage control, in particular to a control method for a storage battery energy storage system.

Background technique

A battery is an electrochemical device that stores chemical energy and releases electrical energy when necessary. Its working principle: when charging, the external electric energy is used to regenerate the internal active material, the electric energy is stored as chemical energy, and the chemical energy is converted into electric energy output again when it needs to be discharged. The rated capacity of the battery is used to characterize its ability to store electrical energy, that is, the internal electrical energy when the battery is fully charged, and the internal electrical energy will continue to be released as the battery is used. State of Charge (Soc) can be used to characterize the degree of battery energy release. 0 means that the net discharge capacity reaches the rated capacity.

Due to the influence of the internal electrochemical reaction process, the charging and discharging process of the battery is subject to a series of constraints: For the charging process, not any charging current can be accepted by the battery, there is a maximum acceptable current, the maximum acceptable current size It depends on the remaining capacity of the battery at the time of charging; at the same time, the value of the maximum acceptable current is not constant during the charging process, but will decrease with the increase of the remaining capacity of the battery. For the discharge process, the discharge capacity of the battery is constrained by the discharge current. The larger the discharge current, the less the total power that the battery can discharge, and the shorter the duration of the discharge process; the smaller the discharge current, the less the total power that the battery can discharge. The larger the value, the longer the duration of the discharge process.

In the battery energy storage system, in order to give full play to the energy conversion efficiency, it is necessary to establish an energy management platform to manage and control the charging and discharging of the battery.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a battery energy storage system control method with reasonable design and sufficient energy conversion efficiency.

The present invention solves its technical problem and realizes by taking the following technical solutions:

A method for controlling a battery energy storage system, comprising the following steps:

Step 1. Read the state of charge Soc(t) of the battery at the current moment;

Step 2. Estimate the exchange power P _ex between the storage battery and the outside within Δt according to the load prediction results of the system within Δt in the future;

Step 3. According to the operating voltage of the storage battery system, calculate the exchange current I _ex = P _ex /U between the inside and outside of Δt;

Step 4. If the exchange current I _ex > 0, it means that the battery is discharged, go to step 5, otherwise go to step 6;

Step 5, battery discharge control step;

Step 6, the battery charging control step.

Moreover, the specific process of step 5 is: calculate the maximum dischargeable current I _outmax of the battery within Δt, if I _outmax ≥ I _ex , mark the battery as capable of supplying power, and calculate the state of charge Soc(t+Δt) of the battery after discharge as For reference; if I _outmax < I _ex , the system will prompt a power-out warning message.

Moreover, the calculation of the maximum dischargeable current I _outmax of the storage battery within Δt adopts the following formula:

$\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; SoC</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; out</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}}$

Among them, SoC(t-1) is the state of charge of the battery at the initial moment of discharge, T is the continuous discharge time T of the battery, and K and n are constants that depend on the self-discharging characteristics of different batteries.

Moreover, the following formula is used for calculating the state of charge of the storage battery after discharge:

Among them, t is the actual discharge time under the current I _out , C _N is the rated capacity of the battery, and SoC(t) is the state of charge of the battery after the discharge is completed.

Moreover, the specific process of step 6 is: calculate the acceptable current of the storage battery and the charging capacity C _in of the storage battery within the charging time t, the charging current I _in <I ₀ , the storage battery is charged with a constant current of I _in ; otherwise, estimate The maximum critical charging current I _inmax of the battery within Δt, and the control system charges the battery with I _inmax , and at the same time prompts that there is excess power in the system and part of the power supply needs to be cut off.

Moreover, the calculation of the acceptable current of the storage battery adopts the following formula:

I＝I ₀ e ^-at

Among them, I ₀ is the maximum initial current value allowed at the beginning of charging, and α is the charge acceptance ratio of the battery, which is used to characterize the charge acceptance characteristics of the battery.

Moreover, the calculation of the charging capacity C _in of the storage battery within the charging time t adopts the following formula:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&alpha;t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}<span\; class="notranslate">\; \&Greater\; Equal;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}}{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; t</span>}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&Greater\; Equal;</span>\mathrm{<span\; class="notranslate">\; t</span>}\end{array}\right.$

in, I ₀ =αC _R , C _R =(1-SoC(t-1))Cx, SoC(t-1) is the state of charge of the battery before charging, and C _N is the rated capacity of the energy storage.

Moreover, the calculation method of the maximum critical charging current I _inmax is: make the critical moment T=Δt in the discharge simulation process, that is $\mathrm{\&Delta;t}=C_R/I_{\mathrm{in}\max }-I_{\mathrm{in}\max }/K_0^2,$ so as to calculate $I_{\mathrm{in}\max }={-K}_0^2\mathrm{\&Delta;t}\&PlusMinus;0.5\sqrt{K_0^4{\mathrm{\&Delta;t}}^2+4K_0^2{C}_R},$ Take the positive I _inmax in this formula is the battery charging current under control.

Moreover, the part of the power supply that needs to be removed is (I _ex −I _inmax )U.

Advantage and positive effect of the present invention are:

The design of the invention is reasonable. According to the change of electric quantity inside the storage battery under different charging and discharging currents, it implements the optimal management and control of the storage battery energy storage system, effectively improves the energy conversion efficiency of the storage battery storage system, and can be widely used in the electric energy storage system. Energy management and control by energy storage devices in car charging stations, microgrids or UPS systems.

Description of drawings

Figure 1 is a schematic diagram of the first charging situation when the battery is being charged;

Fig. 2 is a schematic diagram of the second charging situation when the battery is being charged;

Fig. 3 is a schematic diagram of the third charging situation when the battery is being charged.

detailed description

Below in conjunction with accompanying drawing, the present invention is described in further detail:

A method for controlling a battery energy storage system, comprising the following steps:

Step 1. Read the state of charge Soc(t) of the battery at the current moment;

Step 2. Estimate the exchange power P _ex between the storage battery and the outside within Δt according to the load prediction results of the system within Δt in the future;

Step 3. According to the operating voltage of the storage battery system, calculate the exchange current I _ex = P _ex /U between the inside and outside of Δt;

Step 4. If I _ex > 0, it means that the battery is discharged, go to step 5, otherwise go to step 6;

Step 5, battery discharge process: calculate the maximum dischargeable current I _outmax of the battery within Δt according to formula (1), if I _outmax ≥ I _ex , mark the battery as capable of supplying power, and calculate the state of charge of the battery after discharge according to formula (2) Soc(t+Δt) is used as a reference; if I _outmax <I _ex , a system power-out warning message will be prompted.

During the discharge process, the electric energy that the battery can release is limited by the discharge current, the greater the discharge current, the less the dischargeable capacity. Assuming that the state of charge of the battery at the initial discharge moment is SoC(t-1), at a certain discharge current level I _out , the battery’s sustainable discharge time T can be described by the Peukert discharge formula:

$\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; SoC</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; out</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, K and n are constants depending on the self-discharging characteristics of different batteries, which can be obtained through experiments.

According to the above principles, the battery discharge process simulation can be expressed as:

Among them, t is the actual discharge time under the current I _out , C _N is the rated capacity of the battery, SoC(t) is the state of charge of the battery after the discharge is completed, that is, after the discharge is terminated, the state of charge of the battery is the state of charge at the end of the discharge The electrical state is (C _N ×SoC(t-1)-I _out ×T)/C _N .

The control principle of the discharge process: when the current I _out is continuously discharged, the maximum discharge time that the battery can maintain is T. If the actual discharge time t≤T, then after the end of the discharge, the electricity discharged by the battery is C _N ×SoC(t-1)-I _out ×t, and the state of charge after the end of the discharge is (C _N ×SoC(t-1 )-I _out ×T)/C _N ; if t≥T, the battery cannot continue to discharge at the level of I _out within the time t, indicating that it cannot continuously supply power to a specific load.

Step 6, battery charging process: According to formula (3) and formula (4), calculate which situation the charging process of the battery in Δt belongs to in Figure 1 to Figure 3, if it belongs to the third situation (Figure 3), it is normal Start the battery charging function; if it belongs to the first (Figure 1) situation and the second situation (Figure 2), then estimate the maximum critical charging current I _inmax of the battery in Δt according to the corresponding simulation expression in Figure 2, and control the system with I _inmax To charge the battery, at the same time, it prompts that there is excess power in the system, and a part of the power supply needs to be cut off. The power to be cut off is (I _ex -I _inmax )U. The calculation method of I _inmax is: Let the critical moment T=Δt in the discharge simulation process, that is $\mathrm{\&Delta;t}=C_R/I_{\mathrm{in}\max }-I_{\mathrm{in}\max }/K_0^2,$ so as to calculate $I_{\mathrm{in}\max }={-K}_0^2\mathrm{\&Delta;t}\&PlusMinus;0.5\sqrt{K_0^4{\mathrm{\&Delta;t}}^2+4K_0^2{C}_R},$ Take the positive I _inmax in this formula is the battery charging current under control.

During the charging process, not any charging current can be accepted by the battery, and there is a maximum acceptable current. At the same time, the acceptable current will decay exponentially with the charging time, namely:

I＝I ₀ e ^-at (3)

Among them, I ₀ is the maximum initial current value allowed at the beginning of charging, and α is the charge acceptance ratio of the battery, which is used to characterize the charge acceptance characteristics of the battery.

The charging acceptance ratio is related to the charging capacity C _R when the storage battery starts charging with I ₀ , according to Max's law (Mass), K ₀ is a constant of proportionality obtained through experiments. In the process of accepting current decay, the charging acceptance ratio α remains unchanged. The maximum initial charge current can be achieved by calculate.

The battery charging process is shown in Figure 1 to Figure 3.

Figure 1 shows the situation when the constant charging current I _{in in} the unit of time is greater than I ₀ , at this time the maximum accepted current of the battery can only be I ₀ and decay exponentially.

In Fig. 2, the charging current I _in at the initial moment <I ₀ , the battery can be charged with a constant current I _in . But after charging for a certain period of time (less than t), as the capacity to be charged decreases, the maximum initial charging current that the storage battery can accept also decreases. When the new maximum initial charging current _I'0 decreases to equal the charging current _Iin , The accepted current still decays exponentially. At the moment T (critical moment) of I' ₀ =I _in , according to Max's law, $I_0^{\&prime;}=K_0\sqrt{C_R-I_{\mathrm{in}}T},$ therefore $T=C_R/I_{\mathrm{in}}-I_{\mathrm{in}}/K_0^2.$

In Figure 3, there is T≥t, so the battery can always be charged with a constant current I _in within the time t.

The charging capacity C _in of the battery within the charging time t is the integral of each curve in the figure, which can be expressed quantitatively by formula (4):

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&alpha;t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}<span\; class="notranslate">\; \&Greater\; Equal;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}}{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; t</span>}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&Greater\; Equal;</span>\mathrm{<span\; class="notranslate">\; t</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

in, I ₀ =αC _R , C _R =(1-SoC(t-1))C _N , where SoC(t-1) is the state of charge of the battery before charging, and C _N is the rated capacity of the energy storage. After calculating C _in , the state of charge after charging can be obtained as:

SoC(t)＝SoC(t-1)+C _in /C _R (5)

The control principle of the charging process is as follows: (1) When the charging current I _in is very large, the battery can only accept a part of I _in , that is, the maximum acceptable current I ₀ , and I ₀ will decay exponentially during the charging process; ( 2) When the charging current I _in is very small, the battery can be charged at a constant current I _in until the end; (3) When the charging current is between 1) and 3), the battery is charged at a constant current before a certain moment during charging. Charging, after this moment, it will charge with an exponentially decaying current.

The following is an example of an uninterruptible power supply (UPS) system. The system uses a HOPPECKE lead-acid battery, model 24OPzV3000, with a rated capacity of 3000Ah. The battery parameters given by the manufacturer are shown in Table 1.

Table 1 Battery parameters

Discharge time (h) 1 3 5 10 Discharge current (A) 1488 744 504 300

According to the parameters and related tests provided by the manufacturer, it can be measured that the Pickett discharge constant K and n are 34991 and 1.431 respectively, and the proportional constant K0 of Max's law is 95.

At a certain moment, the state of charge of the battery is 90%, and due to a temporary power failure of the external grid for 1 hour, the battery is required to supply power. Calculate the battery discharge current as 900A according to the load required for power supply. The invention is used to calculate whether the accumulator can continuously supply power within 1 hour and the remaining power of the accumulator after power supply. According to the control process of the battery energy storage system, the sustainable discharge time at 900A is calculated to be 1.86 hours, so the marked battery can supply power, and the state of charge of the battery after discharge is 60%.

After the storage battery is discharged for 1 hour, the external power grid resumes power supply. In order to ensure that the UPS power supply has sufficient power, the battery is charged, and the charging time is set to 1h. According to the control flow of the battery energy storage system, the critical charging current of the battery is calculated to be 2328A. After charging for 1 hour, the state of charge of the battery can be calculated as 99.25%.

The control method of the present invention can be well applied to the management and charge and discharge control of the storage battery system, so as to realize accurate prediction and optimized utilization of energy.

It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive, so the present invention includes but not limited to the embodiments described in the specific implementation manner, and those skilled in the art according to the technology of the present invention Other implementations derived from the scheme also belong to the protection scope of the present invention.

Claims (6)

1. A battery energy storage system control method, characterized in that comprising the following steps: Step 1. Read the state of charge Soc(t) of the battery at the current moment; Step 2. Estimate the exchange power P _ex between the storage battery and the outside within Δt according to the load prediction results of the system within Δt in the future; Step 3. According to the operating voltage of the storage battery system, calculate the exchange current I _ex = P _ex /U between the inside and outside of Δt; Step 4. If the exchange current I _ex > 0, it means that the battery is discharged, go to step 5, otherwise go to step 6; Step 5, battery discharge control step, the specific process is: calculate the maximum dischargeable current I _outmax of the battery within Δt, if I _outmax ≥ I _ex , mark that the battery can supply power, and calculate the state of charge SoC(t) of the battery after discharge as For reference; if I _outmax < I _ex , the system will be prompted for a power shortage warning message; Step 6, battery charging control step, the specific processing process is: calculate the acceptable current of the battery and the charging capacity C _in of the battery within the charging time t, the charging current I _in < I ₀ , the battery is charged with a constant current of I _in ; otherwise , to estimate the maximum critical charging current I _inmax of the battery within Δt, and control the system to charge the battery with I _inmax , and at the same time prompt that the system has excess electric energy and part of the power supply needs to be cut off, where I ₀ is the maximum allowable initial current value at the beginning of charging . 2. A control method for a battery energy storage system according to claim 1, wherein the calculation of the maximum dischargeable current I _outmax of the battery within Δt adopts the following formula: $\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; S</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; no</span>}}}$ Among them, SoC(t-1) is the state of charge of the battery at the initial moment of discharge, T is the continuous discharge time of the battery, and K and n are constants that depend on the self-discharging characteristics of different batteries. 3. A control method for a battery energy storage system according to claim 1, wherein the calculation of the state of charge of the battery after discharge uses the following formula: Among them, I _out is the discharge current of the battery, t is the actual discharge time under the current I _out , C _N is the rated capacity of the battery, SoC(t) is the state of charge of the battery after the discharge is completed; SoC(t-1) is State of charge of the battery before discharge; T is the continuous discharge time of the battery. 4. A control method for a battery energy storage system according to claim 1, wherein the calculation of the acceptable current of the battery adopts the following formula: I＝I ₀ e ^-αt Among them, I ₀ is the maximum initial current value allowed at the beginning of charging, and α is the charge acceptance ratio of the battery, which is used to characterize the charge acceptance characteristics of the battery. 5. A battery energy storage system control method according to claim 1, characterized in that: the calculation of the charging capacity C _in of the battery within the charging time t adopts the following formula: ${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&Greater\; Equal;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}}{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; t</span>}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>& {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; \&Greater\; Equal;</span>\mathrm{<span\; class="notranslate">\; t</span>}\end{array}\right.$ in, I ₀ =αC _R , C _R ＝(1-SoC(t-1))C _N , SoC(t-1) is the state of charge of the battery before charging, C _N is the rated capacity of energy storage, K ₀ is the proportional constant of Max’s law, α Acceptance ratio for battery charge. 6 . A control method for a battery energy storage system according to claim 1 , wherein the power of the part of the power supply that needs to be cut off is (I _ex −I _inmax )U.