CN115184809B - Multi-dimensional evaluation method for energy storage battery system based on temperature angle - Google Patents

Abstract

The invention discloses a multi-dimensional evaluation method for an energy storage battery system based on a temperature angle, which belongs to the field of power electronic equipment.

Description

A multi-dimensional evaluation method for energy storage battery system based on temperature perspective

technical field

The invention relates to the field of power electronic equipment, in particular to a multi-dimensional evaluation method for an energy storage battery system based on a temperature angle.

Background technique

With the continuous development of clean energy, solar energy has become the main force of clean energy. However, the inability to store a large amount of power generation has become an existing problem. The life of conventional energy storage batteries is significantly reduced, and effective real-time prediction of the impact of temperature on the life of energy storage batteries is of great significance to the storage and consumption of renewable energy in the construction of new energy development areas in the western region.

In the article "Optimized Design of Microgrid Energy Storage Lithium Battery System in Alpine and High Altitude Areas" published by Zhao Bin and others in "China Electric Power", the performance of discharge capacity is significantly affected by different ambient temperatures. Shorten the cycle life of the battery, and this patent uses the Arrhenius model based on the ambient temperature to predict the battery life, and the thermal cycle capability prediction of the lithium battery capacity performance is more accurate; Zhang Yuechao and others published related patents in 2019. Adjustment strategy for replacement cycle of lead-acid batteries for propellers" Based on the temperature, life relationship curve and historical operating temperature of the unit, the new replacement cycle of the battery at the actual operating temperature is calculated by using the method of life conversion. However, this method is applicable to plains such as Shandong and Liaoning. areas, which limit the application in high-altitude areas, such as Qinghai, Yunnan, Guizhou and other regions; Sun Wei and others published a related patent "A Method for Comprehensive Management of Energy Storage Devices and Energy Storage Devices" in 2014, only focusing on the battery life cycle. The cycle life decay cannot fully characterize the battery life cycle decay mechanism. However, due to ignoring the calendar life attenuation, there will be some prediction deviations. This method has poor real-time performance for high-altitude areas with complex and changeable environmental conditions, which limits its application in high-altitude areas, such as Qinghai, Yunnan, Guizhou and other regions; Tan Zhen and others proposed a related patent in 2019: "Energy Storage Battery Residual Life Evaluation Method, Device, Equipment, and Medium" By obtaining parameters such as the storage battery's shelving and working temperature, the health status of the energy storage battery is repeatedly deduced and calculated , to predict the remaining operating life and remaining shelf life. However, for high-altitude areas, it is necessary to consider the impact of low temperature environment on the energy storage battery capacity, deep discharge and other environmental conditions, and the reason for the large temperature difference between day and night will cause the updated curve to fail immediately after a period of time, so This method is not suitable for regions with extreme temperature environments.

Therefore, there is a need for a method for studying the performance of energy storage batteries in extreme environments, so as to solve the problem of low working efficiency of energy storage batteries in extreme environments.

Contents of the invention

The purpose of the present invention is to provide a multi-dimensional evaluation method for an energy storage battery system based on a temperature angle. Accurately analyze the influence of temperature on the life of the energy storage battery, so as to realize the accurate prediction of the life of the energy storage battery, and the manager can provide corresponding treatment methods for different life situations, so as to maintain the normal operation of the energy storage battery and reduce the failure of the system Rate.

In order to achieve the above purpose, the present invention provides a multi-dimensional evaluation method for the energy storage battery system based on the temperature angle, which evaluates the energy storage battery system from the two dimensions of the influence of the reference environment temperature on the capacity of the energy storage battery and the influence of the operating temperature on the discharge of the energy storage battery. Conduct an assessment, as described below:

In the present invention, the first impact of temperature on the energy storage battery is capacity impact;

S1, using the logarithmic form of the Arrhenius model as the data fitting model;

S2, set the forward index factor A of the energy storage battery, activation energy E _a , molar gas constant R, thermodynamic temperature T, and exponential factor z, and set different ambient temperatures, bring the data into the model respectively, and obtain The logarithmic fitting curve of capacity decay rate Q _loss and cycle time t;

S3, analyze the influence of temperature change on the capacity of the energy storage battery according to the curve;

Preferably, the logarithmic expression of the Arrhenius model for obtaining the capacity decay rate Q _loss and the cycle time t fitting curve is:

Where A is the forward index factor; E _a is the activation energy (J/mol); R is the molar gas constant, which is 8.314J/K mol ^-1 ; T is the thermodynamic temperature (K); z is the exponential factor; Q _loss is Capacity decay rate (%); t is cycle time, unit is day;

In the present invention, the second effect of temperature on the energy storage battery is the effect on discharge capacity;

S1, use the deep discharge experiment method to establish an equivalent model under deep discharge;

S2, using the control variable method, set the loads to 2Ω and 4Ω respectively, connect them to the battery, and set different working temperatures to conduct experiments, and obtain the voltage drop, discharge current, battery capacity and other indicators of the battery under different working temperatures Time change curve;

S3, analyze the influence of the working temperature change on the discharge capacity of the energy storage battery according to the curve;

Preferably, the purpose of establishing an equivalent model of a deeply discharged battery is to obtain the voltage drop, discharge current, and battery capacity of the battery;

Preferably, the experimental process is to discharge the storage battery at a specific discharge rate until the closing voltage reaches 9.5V.

Owing to adopting above-mentioned technical scheme, the technical effect that the present invention obtains is as follows:

The present invention provides an analysis method aiming at the influence of extreme environment on the energy storage battery, from the influence of temperature on the discharge, life, capacity, voltage drop and other indicators of the energy storage battery, and analyzing the influence of the ambient temperature on the performance of the energy storage battery. Targeted countermeasures can improve the working efficiency of energy storage batteries, reduce the adverse effects of extreme environments on energy storage batteries, and provide evidence for monitoring and evaluation of energy storage batteries under extreme environmental conditions.

Description of drawings

Figure 1 Flowchart of analyzing the influence of temperature on the capacity of energy storage batteries;

Fig. 2 Flowchart of analyzing the influence of temperature on the discharge capacity of energy storage batteries;

Figure 3 The battery equivalent model under deep discharge;

Figure 4 The influence of temperature on battery capacity;

Figure 5 Arrhenius model logarithmic fitting curve;

Figure 6 Voltage drop at each temperature under 2Ω load;

Figure 7 Voltage drop at each temperature under 4Ω load;

Figure 8. The discharge current drop at each temperature under 2Ω load;

Figure 9. The discharge current drop at each temperature under 4Ω load;

Figure 10 The battery capacity change at each temperature under 2Ω load;

Figure 11 Changes in battery capacity at each temperature under a 4Ω load.

Detailed ways

In order to make the purpose of the present invention, technical solutions and advantages clearer, the present invention will be further described below in conjunction with accompanying drawing:

The flow chart of patent implementation is shown in Figure 1;

The first is the analysis of the impact of temperature on the capacity of the energy storage battery. The specific implementation steps are as follows:

Step 1, the implementation flow chart is shown in Figure 1, and the logarithmic form of the Arrhenius model is used for data fitting, as shown in formula (1).

Step 2, set different ambient temperatures, take the forward index factor A, activation energy E _a , molar gas constant R, take 8.314J/K·mol-1; thermodynamic temperature T, exponential factor z into the fitting model, and get different The logarithmic fitting curve of the energy storage battery capacity decay rate Q _loss and the cycle time t at ambient temperature is shown in Figure 5. The fitting results using the Arrhenius model are very close to the actual test parameter results. Therefore, the Arrhenius model method can be used to construct a model of the influence of temperature on battery capacity, and the results are in full compliance with the battery decay characteristics of the Arrhenius equation;

Step 3: Set the reference ambient temperature to 25°C, substitute the corresponding parameters into the model, and record the change of battery capacity at this temperature;

Step 4: Set the reference ambient temperature and gradually increase the temperature to 35°C, 45°C, and 55°C, and repeat step 3;

Step 5: Comprehensively analyze the influence of the change of the reference temperature on the battery capacity. With the continuous increase of the cycle time, the influence of different temperatures on the aging speed of the battery capacity.

According to the data sheet of the energy storage battery, the parameters in the energy storage battery model are extracted and substituted into the model, in which the battery voltage is 3.6V, the battery capacity is 2.3Ah, the discharge current is 4A, and the depth of discharge (DOD) is 90%. In order to evaluate the impact of ambient temperature on energy storage batteries, a certain type of lithium-ion battery is selected. Lithium-ion batteries have the advantages of high energy and power density, low discharge rate, and high cycle life. They are an important part of the energy supply link of industrial production. The primary choice for building a micro-grid energy storage system; at the same time, lead-acid batteries are also selected for research. Lead-acid batteries have the advantages of stable performance, safe use, and low maintenance. They are widely used in daily life, but the complex electrochemical reactions inside the battery Affected by many factors, the temperature factor has a greater impact on its remaining discharge capacity. The life of an energy storage battery is one of its most important parameters, so it is of great significance to study the influence of temperature on its life.

As shown in Figure 4, the Arrhenius model is used to obtain the curve analysis of the influence of temperature changes on the capacity of the energy storage battery. As the temperature increases, the battery capacity gradually decreases; the decay rate of the battery capacity changes throughout the decay process, and The battery capacity loss and cycle time change approximately in a power exponent, which fully conforms to the battery attenuation characteristics based on the Arrhenius equation. When using energy storage batteries in high-altitude areas, according to the corresponding parameters, use the formula (1) to predict the life of the Arrhenius model, and provide corresponding treatment methods for different life conditions to maintain the normal operation of the energy storage battery.

The second aspect of the present invention is the influence of temperature on the discharge capacity of the energy storage battery;

Step 1, the implementation process block diagram is shown in Figure 2, using the deep discharge experiment method to establish a battery equivalent model under deep discharge;

The specific explanation is to establish a battery equivalent model under deep discharge, as shown in Figure 3, which is used for experiments and data recording.

Step 2, using the control variable method, set the loads to 2Ω and 4Ω respectively and connect them to the battery, set different operating temperatures for experiments, and obtain the indicators of voltage drop, discharge current, and battery capacity of the battery at different operating temperatures over time The curves of the changes are shown in Figures 6 and 7.

The specific explanation is to control the change of load and temperature, and discharge the battery at a specific discharge rate until its closing voltage reaches 9.5V. During this period, use the ammeter and voltmeter on the equivalent model to record the changes in voltage and current, and convert them into voltage drop, discharge current, and battery capacity.

Step 3, analyze the influence of the change of working temperature on the discharge capacity of the energy storage battery according to the curve. In terms of voltage drop analysis, it can be seen from the analysis of Figures 6 and 7 that the greater the load, the lower the operating temperature, and the longer the voltage drop will be delayed. After the battery is used for a certain critical time, the voltage will drop significantly, which will seriously affect its discharge work. In the discharge current analysis, it can be seen from the analysis of Figures 8 and 9 that the greater the load, the lower the operating temperature, and the more delayed the current drop is. The difference in current drop between different temperatures is not large, but the temperature drop between different temperatures There is a difference in time, and the current of the battery will drop sharply after a certain critical time, which seriously affects its discharge work. In the analysis of battery capacity, it can be seen from the analysis of Figures 10 and 11 that the greater the load, the greater the discharge capacity of the battery. ℃ environment to work and store in order to reduce the loss of excessive discharge capacity.

The discharge voltage drop, discharge current drop, and battery capacity of the energy storage battery are greatly affected by temperature factors. After the battery is used for a certain critical time, the discharge voltage and current will drop significantly, seriously affecting its discharge quality. Therefore, it needs to be detected early before the critical time to avoid affecting normal work. Especially in plateau areas where the temperature difference between day and night is large, the critical discharge time is not easy to predict, and frequent inspections are required to avoid failures. In addition, the ambient temperature in the plateau area changes rapidly and greatly, which poses great challenges to the working temperature environment of the battery. And it is more suitable for storage and work in the environment of 40 ℃ ~ 50 ℃, so as not to lose too much discharge capacity, it is necessary to choose the storage and working environment properly.

Claims (5)

1. A multi-dimensional evaluation method for an energy storage battery system based on a temperature angle is characterized by comprising the following steps of: the energy storage battery system is evaluated from two dimensions of influence of reference environment temperature on capacity of the energy storage battery and influence of working temperature on discharge of the energy storage battery, and specifically comprises the following steps: from the aspect of influence of reference environment temperature on the capacity of the energy storage battery, researching influence of different environment temperatures on the capacity of the energy storage battery by using an Arrhenius model; from the aspect of influence of the working temperature on the discharge of the energy storage battery, the influence of different working temperatures on the discharge capacity of the energy storage battery is analyzed by using a deep discharge experiment method;

the influence on the capacity of the energy storage battery from the reference ambient temperature specifically comprises the following steps:

step 1.1: extracting forefinger factors, activation energy, molar gas constants, thermodynamic temperatures and index factors from a data manual of the energy storage battery;

step 1.2: and obtaining an equation after fitting analysis of data by using the logarithmic form of an Arrhenius model and obtaining the influence of the temperature on the energy storage battery under different temperatures and aging time through experimental analysis:

wherein A is a forefinger factor; e (E) _a Is activation energy (J/mol); r is molar gas constant, 8.314J/K.mol ^-1 The method comprises the steps of carrying out a first treatment on the surface of the T is the thermodynamic temperature (K); z is an exponential factor; q (Q) _loss Is the capacity attenuation rate (%); t is cycle time in days;

step 1.3: setting the reference environment temperature to 25 ℃, substituting corresponding parameters into the model, and recording the change condition of the battery capacity at the temperature;

step 1.4: setting the temperature of the reference environment to be gradually increased to 35 ℃, 45 ℃ and 55 ℃ in sequence, and repeating the step 1.3;

step 1.5: comprehensively analyzing the influence of the change of the reference temperature on the battery capacity, increasing the capacity released by the battery along with the increase of the temperature, and accelerating the aging of the battery at high temperature in the actual use process, wherein the optimal discharging temperature of the storage battery is 20-40 ℃;

the evaluation of the discharge effect of the energy storage battery from the operating temperature comprises the following steps:

step 2.1: obtaining indexes of voltage drop, discharge current and battery capacity at a specified ambient temperature by adopting a deep discharge experiment method, and establishing an equivalent model of a deep discharge test condition;

step 2.2: connecting an energy storage battery with a load of 2 omega, setting the working temperature to be 30 ℃, and observing and recording the voltage drop, the discharge current and the change condition of the battery capacity index along with time;

step 2.3: setting the working temperature to be gradually increased to 40 ℃ and 50 ℃ in sequence, and repeating the step 2.2;

step 2.4: connecting the energy storage battery with a load of 4Ω, and repeating steps 2.2 and 2.3;

step 2.5: and comprehensively analyzing the influence of the working temperature change on the discharge capacity of the energy storage battery.

2. The method for multi-dimensional evaluation of an energy storage battery system based on a temperature angle according to claim 1, wherein the method comprises the following steps:

the electrical parameters of the energy storage battery required to be extracted in the step 1.1 refer to parameters of a forefinger factor, activation energy, molar gas constant, thermodynamic temperature and an index factor of the lithium ion battery.

3. The method for multi-dimensional evaluation of an energy storage battery system based on a temperature angle according to claim 1, wherein the method comprises the following steps: the energy storage battery voltage in the step 1.2 is 3.6V, the battery capacity is 2.3Ah, the discharge current is 4A, and the depth of discharge DOD is 90%.

4. The method for multi-dimensional evaluation of an energy storage battery system based on a temperature angle according to claim 1, wherein the method comprises the following steps: the deep discharge experiment method described in step 2.1 specifically refers to discharging the storage battery to a closing voltage of 9.5V at a specific discharge rate.

5. The method for multi-dimensional evaluation of an energy storage battery system based on a temperature angle according to any one of claims 1-4, wherein: the energy storage battery is any one of a lithium battery and a lead-acid battery.

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