Charging and discharging control method for off-grid solar storage battery

Abstract

The invention relates to charge and discharge control of a storage battery, in particular to a charge and discharge control method of an off-grid solar storage battery, which comprises the following steps: collecting state parameters of the storage battery, determining charge and discharge states of the storage battery, and predicting the SOH (state of health) of the storage battery; according to the state parameter, the charging and discharging state and the health state SOH of the storage battery, a charging and discharging strategy of the energy storage system is determined, and charging and discharging control is carried out on the storage battery; when the energy storage system is in a constant-current charging mode, charging parameters are corrected by utilizing a Mass ideal charging curve MCC of the storage battery; according to the technical scheme provided by the invention, the defects that the charging and discharging strategy of the optical energy storage system is difficult to accurately formulate and the temperature of the storage battery may rise in the constant-current charging process in the prior art can be effectively overcome.

Description

Technical Field

[0001] The invention relates to battery charge and discharge control, and in particular to a charge and discharge control method for an off-grid solar battery. Background Art

[0002] In recent years, with the widespread popularity of new energy vehicles, charging stations, battery swap stations and battery swap cabinets have also been fully built. Due to the low cost of solar photovoltaic power generation, it has been widely applied and promoted, and more and more solar energy storage systems using solar photovoltaic power generation technology have been used.

[0003] How to formulate the charging and discharging strategy of the photovoltaic energy storage system more comprehensively and accurately, so as to improve the charging and discharging efficiency of the photovoltaic energy storage system and the service life of the battery, is an urgent problem to be solved. In addition, the charging current is constant during constant current charging, and according to Maas's law, the acceptable current of the battery decreases exponentially with the charging time during the charging process. If constant current charging is used for a long time, the electrolyte may undergo gasification reaction or temperature rise in the later stage of charging due to the charging current exceeding the acceptable current, thereby affecting the service life of the battery. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a charge and discharge control method for an off-grid solar battery, which can effectively overcome the defects of the prior art that it is difficult to accurately formulate a charge and discharge strategy for a light energy storage system, and that the battery may experience temperature rise during constant current charging.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A method for controlling the charging and discharging of an off-grid solar battery comprises the following steps:

[0009] S1. Collect the state parameters of the battery, determine the charge and discharge state of the battery, and predict the health state SOH of the battery;

[0010] S2. Determine the charge and discharge strategy of the energy storage system according to the state parameters, charge and discharge state and health state SOH of the battery, and control the charge and discharge of the battery;

[0011] Among them, when the energy storage system is in constant current charging mode, the charging parameters are corrected using the Maas ideal charging curve MCC of the battery.

[0012] Preferably, collecting the state parameters of the battery, determining the charge and discharge state of the battery, and predicting the state of health SOH of the battery in S1 includes:

[0013] Determine the state of charge SOC of the battery according to the state parameters of the battery;

[0014] Determine the charge and discharge state of the battery according to the change of the state of charge (SOC) of the battery within a preset time period;

[0015] The battery's state of health SOH is predicted based on the battery's state of charge SOC and the battery's factory capacity.

[0016] Preferably, determining the state of charge SOC of the battery according to the state parameters of the battery includes:

[0017] According to the state parameters of the battery, the Kalman filter KF is used to estimate the state of charge SOC of the battery.

[0018] Preferably, in S2, the charge and discharge strategy of the energy storage system is determined according to the state parameters, charge and discharge state and health state SOH of the battery, and the charge and discharge of the battery is controlled, including:

[0019] Determine the charging mode of the energy storage system at different stages according to the battery's state of charge SOC, a preset charging state of charge SOC threshold, a health state SOH, a preset charging health state SOH threshold, a battery voltage, and a preset charging voltage threshold;

[0020] According to the charging mode of the energy storage system at different stages, the charging and discharging strategy of the energy storage system is determined, and the charging and discharging of the battery is controlled.

[0021] Preferably, the method of determining the charging mode of the energy storage system at different stages according to the state of charge SOC of the battery, a preset charging state of charge SOC threshold, the state of health SOH, a preset charging state of health SOH threshold, the battery voltage and the preset charging voltage threshold includes:

[0022] If it is detected that the battery's state of health SOH is not greater than a preset charge state of health SOH threshold, and the battery's state of charge SOC is not greater than a first preset charge state of charge SOC threshold, the energy storage system enters a constant current charging mode;

[0023] When the energy storage system is in the constant current charging mode, if it is detected that the battery voltage of the battery is greater than the preset charging voltage threshold, the energy storage system enters the constant voltage charging mode;

[0024] When the energy storage system is in the constant voltage charging mode, if it is detected that the state of charge SOC of the battery is greater than the second preset state of charge SOC threshold, the energy storage system enters the floating charging mode;

[0025] When the energy storage system is in the floating charge mode, if it is detected that the state of charge (SOC) of the battery reaches a third preset state of charge (SOC) threshold, the energy storage system stops charging.

[0026] Preferably, when the energy storage system is in constant current charging mode, the charging parameters are corrected using the Maas ideal charging curve MCC of the battery, including:

[0027] Obtain battery charge and discharge data and determine battery charging parameters;

[0028] According to the battery charging parameters and the Maas ideal charging curve MCC, the battery is charged for a preset time;

[0029] The charging parameters of the battery are corrected by discharging the battery for a preset time.

[0030] Preferably, the acquiring of the charging and discharging data of the battery includes:

[0031] Acquire a charging state parameter representing a characteristic quantity exhibited by the battery during the charging process, acquire a discharging state parameter representing a characteristic quantity exhibited by the battery during the discharging process, and use the charging state parameter and the discharging state parameter as charging and discharging data of the battery;

[0032] The charging state parameters include the charging capacity and the charging start and end voltages, and the discharging state parameters include the discharging capacity and the discharging start and end voltages.

[0033] Preferably, the determining of the charging parameters of the battery includes:

[0034] Determine an approximate charging class from multiple charging classes according to the charging and discharging data of the battery, and obtain the class charging parameters of the battery;

[0035] According to the charging and discharging data of the battery, the charging time corresponding to the Maas ideal charging curve MCC is determined, and the charging parameters and charging time are used as the charging parameters of the battery;

[0036] Among them, the charging class includes multiple groups of basic charging and discharging data and their corresponding class charging parameters, and the charging class is obtained by clustering using the K-means algorithm.

[0037] Preferably, determining an approximate charging class from a plurality of charging classes according to the charging and discharging data of the battery to obtain the class charging parameters of the battery includes:

[0038] Calculate the distance between the charge and discharge data of the battery and each basic charge and discharge data in multiple charging categories;

[0039] The charging class containing the largest number of basic charging and discharging data with distances less than a preset distance threshold is used as the approximate charging class, and the class charging parameters corresponding to the approximate charging class are used as the class charging parameters of the battery.

[0040] Preferably, the step of correcting the charging parameters of the battery by discharging the battery for a preset time period includes:

[0041] Obtaining the charging process capacity and the charging process start and end voltages of the battery during the charging process of a preset duration, discharging the battery for a preset duration according to the charging process start and end voltages, and obtaining the discharging process capacity;

[0042] The capacity difference between the charging process capacity and the discharging process capacity is calculated, and the charging parameters of the battery are corrected according to the capacity difference.

[0043] (III) Beneficial effects

[0044] Compared with the prior art, the off-grid solar battery charge and discharge control method provided by the present invention has the following beneficial effects:

[0045] 1) Collect the state parameters of the battery, determine the charge and discharge state of the battery, and predict the health state SOH of the battery. According to the battery state of charge SOC, preset charge state of charge SOC threshold, health state SOH, preset charge health state SOH threshold, battery voltage and preset charging voltage threshold, determine the charging mode of the energy storage system at different stages. According to the charging mode of the energy storage system at different stages, determine the charge and discharge strategy of the energy storage system, and control the charge and discharge of the battery, so as to formulate the charge and discharge strategy of the solar energy storage system more comprehensively and accurately, realize efficient charge and discharge control of the battery, and effectively improve the charge and discharge efficiency of the solar energy storage system and the service life of the battery;

[0046] 2) When the energy storage system is in constant current charging mode, the charging and discharging data of the battery is obtained, and the charging parameters of the battery are determined. According to the charging parameters of the battery and the Maas ideal charging curve MCC, the battery is charged for a preset time. By discharging the battery for a preset time, the charging parameters of the battery are corrected, so that the charging parameters of the battery can be effectively corrected during the constant current charging process, avoiding gassing reaction or temperature rise of the electrolyte due to the charging current exceeding the acceptable current in the later stage of constant current charging, thereby further improving the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 It is a schematic diagram of the process of the present invention;

[0049] Figure 2 A schematic diagram of a flow chart for determining a charging and discharging strategy for an energy storage system and controlling charging and discharging of a storage battery in the present invention;

[0050] Figure 3 It is a schematic diagram of a flow chart of correcting the charging parameters of a battery when the energy storage system is in a constant current charging mode in the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] A method for controlling the charging and discharging of an off-grid solar battery, such as Figure 1 and Figure 2 As shown, ① collect the state parameters of the battery, determine the charge and discharge state of the battery, and predict the health state SOH of the battery, specifically including:

[0053] Determine the state of charge SOC of the battery according to the state parameters of the battery;

[0054] Determine the charge and discharge state of the battery according to the change of the state of charge (SOC) of the battery within a preset time period;

[0055] The battery's state of health SOH is predicted based on the battery's state of charge SOC and the battery's factory capacity.

[0056] Specifically, determining the state of charge SOC of the battery according to the state parameters of the battery includes:

[0057] According to the state parameters of the battery, the Kalman filter KF is used to estimate the state of charge SOC of the battery.

[0058] ② According to the battery status parameters, charge and discharge status and health status SOH, determine the charge and discharge strategy of the energy storage system and control the charge and discharge of the battery, including:

[0059] Determine the charging mode of the energy storage system at different stages according to the battery's state of charge SOC, a preset charging state of charge SOC threshold, a health state SOH, a preset charging health state SOH threshold, a battery voltage, and a preset charging voltage threshold;

[0060] According to the charging mode of the energy storage system at different stages, the charging and discharging strategy of the energy storage system is determined, and the charging and discharging of the battery is controlled.

[0061] Specifically, according to the state of charge SOC of the battery, the preset charge state of charge SOC threshold, the state of health SOH, the preset charge state of health SOH threshold, the battery voltage and the preset charge voltage threshold, the charging mode of the energy storage system at different stages is determined, including:

[0062] If it is detected that the battery's state of health SOH is not greater than a preset charge state of health SOH threshold, and the battery's state of charge SOC is not greater than a first preset charge state of charge SOC threshold, the energy storage system enters a constant current charging mode;

[0063] When the energy storage system is in the constant current charging mode, if it is detected that the battery voltage of the battery is greater than the preset charging voltage threshold, the energy storage system enters the constant voltage charging mode;

[0064] When the energy storage system is in the constant voltage charging mode, if it is detected that the state of charge SOC of the battery is greater than a second preset state of charge SOC threshold, the energy storage system enters the floating charging mode;

[0065] When the energy storage system is in the floating charge mode, if it is detected that the state of charge (SOC) of the battery reaches a third preset state of charge (SOC) threshold, the energy storage system stops charging.

[0066] The above technical scheme collects the state parameters of the battery, determines the charging and discharging state of the battery, and predicts the health state SOH of the battery. According to the battery state of charge SOC, a preset charging state of charge SOC threshold, health state SOH, a preset charging health state SOH threshold, battery voltage and a preset charging voltage threshold, the charging mode of the energy storage system at different stages is determined. According to the charging mode of the energy storage system at different stages, the charging and discharging strategy of the energy storage system is determined, and the charging and discharging of the battery is controlled, so that the charging and discharging strategy of the solar energy storage system can be formulated more comprehensively and accurately, and efficient charging and discharging control of the battery can be achieved, effectively improving the charging and discharging efficiency of the solar energy storage system and the service life of the battery.

[0067] like Figure 1 and Figure 3 As shown, when the energy storage system is in constant current charging mode, the charging parameters are corrected using the Maas ideal charging curve MCC of the battery, including:

[0068] Obtain battery charge and discharge data and determine battery charging parameters;

[0069] According to the battery charging parameters and the Maas ideal charging curve MCC, the battery is charged for a preset time;

[0070] The charging parameters of the battery are corrected by discharging the battery for a preset time.

[0071] 1) Obtain battery charge and discharge data, including:

[0072] Acquire a charging state parameter representing a characteristic quantity exhibited by the battery during the charging process, acquire a discharging state parameter representing a characteristic quantity exhibited by the battery during the discharging process, and use the charging state parameter and the discharging state parameter as charging and discharging data of the battery;

[0073] The charging state parameters include the charging capacity and the charging start and end voltages, and the discharging state parameters include the discharging capacity and the discharging start and end voltages.

[0074] 2) Determine the battery charging parameters, including:

[0075] Determine an approximate charging class from multiple charging classes according to the charging and discharging data of the battery, and obtain the class charging parameters of the battery;

[0076] According to the charging and discharging data of the battery, the charging time corresponding to the Maas ideal charging curve MCC is determined, and the charging parameters and charging time are used as the charging parameters of the battery;

[0077] Among them, the charging class includes multiple groups of basic charging and discharging data and their corresponding class charging parameters, and the charging class is obtained by clustering using the K-means algorithm.

[0078] Specifically, an approximate charging class is determined from multiple charging classes according to the charging and discharging data of the battery, and the class charging parameters of the battery are obtained, including:

[0079] Calculate the distance between the charge and discharge data of the battery and each basic charge and discharge data in multiple charging categories;

[0080] The charging class containing the largest number of basic charging and discharging data with distances less than a preset distance threshold is used as the approximate charging class, and the class charging parameters corresponding to the approximate charging class are used as the class charging parameters of the battery.

[0081] 3) Correcting the charging parameters of the battery by discharging the battery for a preset time, including:

[0082] Obtaining the charging process capacity and the charging process start and end voltages of the battery during the charging process of a preset duration, discharging the battery for a preset duration according to the charging process start and end voltages, and obtaining the discharging process capacity;

[0083] The capacity difference between the charging process capacity and the discharging process capacity is calculated, and the charging parameters of the battery are corrected according to the capacity difference.

[0084] The above technical solution, when the energy storage system is in the constant current charging mode, obtains the charging and discharging data of the battery, determines the charging parameters of the battery, charges the battery for a preset time according to the charging parameters of the battery and the Maas ideal charging curve MCC, and corrects the charging parameters of the battery by discharging the battery for a preset time, thereby being able to effectively correct the charging parameters of the battery during the constant current charging process, avoiding the occurrence of gasification reaction or temperature rise of the electrolyte due to the charging current exceeding the acceptable current in the later stage of constant current charging, and further improving the service life of the battery.

[0085] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A charge and discharge control method for an off-grid solar battery, characterized in that: The following steps are involved: S1. Collect the state parameters of the battery, determine the charge and discharge state of the battery, and predict the health state SOH of the battery; S2. Determine the charge and discharge strategy of the energy storage system according to the state parameters, charge and discharge state and health state SOH of the battery, and control the charge and discharge of the battery; Among them, when the energy storage system is in constant current charging mode, the charging parameters are corrected using the Maas ideal charging curve MCC of the battery.

2. The off-grid solar battery charge and discharge control method according to claim 1, characterized in that: S1 collects the battery status parameters, determines the battery charge and discharge status, and predicts the battery health status SOH, including: Determine the state of charge SOC of the battery according to the state parameters of the battery; Determine the charge and discharge state of the battery according to the change of the state of charge (SOC) of the battery within a preset time period; The battery's state of health SOH is predicted based on the battery's state of charge SOC and the battery's factory capacity.

3. The off-grid solar battery charge and discharge control method according to claim 2, characterized in that: Determining the state of charge (SOC) of the battery according to the state parameter of the battery includes: According to the state parameters of the battery, the Kalman filter KF is used to estimate the state of charge SOC of the battery.

4. The off-grid solar battery charge and discharge control method according to claim 2, characterized in that: In S2, the charging and discharging strategy of the energy storage system is determined according to the state parameters, charging and discharging state and health state SOH of the battery, and the charging and discharging of the battery is controlled, including: Determine the charging mode of the energy storage system at different stages according to the battery's state of charge SOC, a preset charging state of charge SOC threshold, a health state SOH, a preset charging health state SOH threshold, a battery voltage, and a preset charging voltage threshold; According to the charging mode of the energy storage system at different stages, the charging and discharging strategy of the energy storage system is determined, and the charging and discharging of the battery is controlled.

5. The off-grid solar battery charge and discharge control method according to claim 4, characterized in that: The method of determining the charging mode of the energy storage system at different stages according to the battery state of charge SOC, a preset charging state of charge SOC threshold, a health state SOH, a preset charging health state SOH threshold, a battery voltage and a preset charging voltage threshold includes: If it is detected that the battery's state of health SOH is not greater than a preset charge state of health SOH threshold, and the battery's state of charge SOC is not greater than a first preset charge state of charge SOC threshold, the energy storage system enters a constant current charging mode; When the energy storage system is in the constant current charging mode, if it is detected that the battery voltage of the battery is greater than the preset charging voltage threshold, the energy storage system enters the constant voltage charging mode; When the energy storage system is in the constant voltage charging mode, if it is detected that the state of charge SOC of the battery is greater than the second preset state of charge SOC threshold, the energy storage system enters the floating charging mode; When the energy storage system is in the floating charge mode, if it is detected that the state of charge (SOC) of the battery reaches a third preset state of charge (SOC) threshold, the energy storage system stops charging.

6. The off-grid solar battery charge and discharge control method according to claim 1, characterized in that: When the energy storage system is in constant current charging mode, the charging parameters are corrected using the Maas ideal charging curve MCC of the battery, including: Obtain battery charge and discharge data and determine battery charging parameters; According to the battery charging parameters and the Maas ideal charging curve MCC, the battery is charged for a preset time; The charging parameters of the battery are corrected by discharging the battery for a preset time.

7. The off-grid solar battery charge and discharge control method according to claim 6, characterized in that: The obtaining of the charging and discharging data of the storage battery comprises: Acquire a charging state parameter representing a characteristic quantity exhibited by the battery during the charging process, acquire a discharging state parameter representing a characteristic quantity exhibited by the battery during the discharging process, and use the charging state parameter and the discharging state parameter as charging and discharging data of the battery; The charging state parameters include the charging capacity and the charging start and end voltages, and the discharging state parameters include the discharging capacity and the discharging start and end voltages.

8. The off-grid solar battery charge and discharge control method according to claim 7, characterized in that: The step of determining the charging parameters of the battery comprises: Determine an approximate charging class from multiple charging classes according to the charging and discharging data of the battery, and obtain the class charging parameters of the battery; According to the charging and discharging data of the battery, the charging time corresponding to the Maas ideal charging curve MCC is determined, and the charging parameters and charging time are used as the charging parameters of the battery; Among them, the charging class includes multiple groups of basic charging and discharging data and their corresponding class charging parameters, and the charging class is obtained by clustering using the K-means algorithm.

9. The off-grid solar battery charge and discharge control method according to claim 8, characterized in that: The method of determining an approximate charging class from a plurality of charging classes according to the charging and discharging data of the battery and obtaining the class charging parameters of the battery includes: Calculate the distance between the charge and discharge data of the battery and each basic charge and discharge data in multiple charging categories; The charging class containing the largest number of basic charging and discharging data with distances less than a preset distance threshold is used as the approximate charging class, and the class charging parameters corresponding to the approximate charging class are used as the class charging parameters of the battery.

10. The off-grid solar battery charge and discharge control method according to claim 8, characterized in that: The method of correcting the charging parameters of the battery by discharging the battery for a preset time period includes: Obtaining the charging process capacity and the charging process start and end voltages of the battery during the charging process of a preset duration, discharging the battery for a preset duration according to the charging process start and end voltages, and obtaining the discharging process capacity; The capacity difference between the charging process capacity and the discharging process capacity is calculated, and the charging parameters of the battery are corrected according to the capacity difference.

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