Charging and discharging control method and system for energy storage converter

Abstract

The invention provides a charging and discharging control method and system for an energy storage converter. The charging and discharging control method comprises the following steps: S1, acquiring a charging / discharging efficiency table of the energy storage converter; s2, after the energy storage converter receives the charging / discharging instruction, the charging / discharging object is started to be charged / discharged; s3, in the charging / discharging process, the current voltage value of the charging / discharging object is monitored in real time or periodically, the corresponding highest charging / discharging efficiency is obtained according to the charging / discharging efficiency table, and then the ratio of the corresponding required power to the rated power is obtained according to the highest charging / discharging efficiency; and S4, calculating the required power during charging / discharging of the energy storage converter according to the ratio of the required power to the rated power, and synchronously adjusting the required power into the actual power during charging / discharging of the energy storage converter. According to the scheme, the energy storage converter can run with the highest charging / discharging efficiency corresponding to the current voltage value of the charging / discharging object in the whole charging / discharging process, the charging / discharging efficiency can be improved, and energy loss in the charging / discharging process is reduced.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a method and system for controlling charging and discharging of an energy storage converter. Background Art

[0002] The energy storage converter (PCS) can control the charging and discharging process of the battery, perform AC / DC conversion, and directly supply power to the AC load when there is no power grid. As a key component of energy storage conversion, the charging and discharging efficiency of the energy storage converter is an important performance parameter of the product. Existing energy storage converters only focus on the highest efficiency point of the product, but do not care about the actual charging and discharging efficiency of the energy storage converter.

[0003] At present, the mainstream charging and discharging control method of energy storage inverters is constant power charging and discharging. The host computer inputs the target charging and discharging power, and the energy storage inverter continues to operate at this power. Whether in the charging or discharging process, the voltage of the energy storage inverter is constantly changing. Under different battery voltages and different powers, the actual charging and discharging efficiency of the energy storage inverter is different. Some manufacturers also provide constant current and constant voltage charging and discharging modes. However, the energy storage inverter cannot always operate in the high efficiency area of ​​the product when charging and discharging with constant power, constant voltage, and constant current. Summary of the invention

[0004] Based on the above problems existing in the prior art, the present invention aims to solve the technical problem that the charging and discharging control method in the prior art cannot enable the energy storage converter to always maintain a high charging and discharging efficiency.

[0005] The present invention provides a method for controlling charging and discharging of an energy storage converter, which comprises the following steps:

[0006] S1: Obtaining a charge / discharge efficiency table of the energy storage converter, wherein the charge / discharge efficiency table includes the maximum charge / discharge efficiency of the energy storage converter corresponding to different voltage values ​​of the charge / discharge object during the charge / discharge process and the ratio of the actual power to the rated power of the energy storage converter during the charge / discharge process;

[0007] S2: After receiving the charge / discharge instruction from the background, the energy storage converter starts to charge / discharge the charge / discharge object;

[0008] S3: During the charging / discharging process, the current voltage value of the charging / discharging object is monitored in real time or periodically, and the maximum charging / discharging efficiency corresponding to the current voltage value is obtained according to the charging / discharging efficiency table, and then the corresponding required power and rated power ratio is obtained according to the maximum charging / discharging efficiency;

[0009] S4: Calculate the required power of the energy storage converter when charging / discharging according to the ratio of the required power to the rated power, and adjust it to the actual power of the energy storage converter when charging / discharging, so that the energy storage converter operates at the highest charging / discharging efficiency corresponding to the current voltage value of the charging / discharging object during the charging / discharging process.

[0010] According to an embodiment of the present invention, in step S2, after the energy storage converter receives the charge / discharge instruction, before starting to charge / discharge the charge / discharge object, it also includes:

[0011] Obtaining an initial voltage value of the charge / discharge object, querying a charge / discharge efficiency table to obtain a maximum charge / discharge efficiency corresponding to the initial voltage value, and querying the charge / discharge efficiency table again to obtain a ratio of actual power to rated power of the energy storage converter during charging / discharging corresponding to the maximum charge / discharge efficiency;

[0012] The initial power when the energy storage converter starts charging / discharging is calculated according to the ratio of the actual power to the rated power, and the energy storage converter starts charging / discharging the charging / discharging object with the calculated initial power.

[0013] According to an embodiment of the present invention, both the initial voltage value and the current voltage value are acquired by a voltage sensor.

[0014] According to one embodiment of the present invention, in step S3, when obtaining the highest charge / discharge efficiency corresponding to the current voltage value according to the charge / discharge efficiency table, and obtaining the corresponding ratio of actual power to rated power according to the highest charge / discharge efficiency, a linear interpolation method is used to obtain the highest charge / discharge efficiency corresponding to the current voltage value and not recorded in the charge / discharge efficiency table, and the ratio of actual power to rated power of the energy storage converter corresponding to the highest charge / discharge efficiency.

[0015] According to an embodiment of the present invention, the charge / discharge efficiency table of the energy storage converter is obtained by multiple measurements with a power analyzer at different voltage points on the DC side of the energy storage power station system and power points of the energy storage converter.

[0016] According to an embodiment of the present invention, the charging / discharging object is a battery pack.

[0017] The present invention also provides a charge and discharge control system for an energy storage converter, which comprises:

[0018] The charge / discharge efficiency table records the maximum charge / discharge efficiency of the energy storage converter corresponding to different voltage values ​​of the charge / discharge object during the charge / discharge process and the ratio of the required power to the rated power of the energy storage converter during charge / discharge;

[0019] The communication module establishes a communication connection with the energy storage converter, and is used to send the received background charge / discharge instruction to the energy storage converter, and the energy storage converter charges / discharges the charge / discharge object according to the received charge / discharge instruction;

[0020] A voltage monitoring module is used to monitor the current voltage value of the charging / discharging object in real time or periodically during the charging / discharging process;

[0021] a query module, establishing communication or electrical connection with the charge / discharge efficiency table and the voltage monitoring module respectively, for querying the charge / discharge efficiency table to obtain the maximum charge / discharge efficiency corresponding to the current voltage value of the charge / discharge object and the ratio of the required power corresponding to the maximum charge / discharge efficiency to the rated power;

[0022] A calculation module, which establishes communication or electrical connection with the query module, and is used to calculate the required power of the energy storage converter when charging / discharging according to the ratio of the required power to the rated power;

[0023] The adjustment module establishes communication or electrical connection with the calculation module and the energy storage converter respectively, so as to adjust the actual power of the energy storage converter during charging / discharging synchronously according to the calculated required power of the energy storage converter during charging / discharging.

[0024] According to an embodiment of the present invention, the voltage monitoring module is a voltage sensor.

[0025] The beneficial effects of the present invention are:

[0026] The present invention provides a method and system for controlling charging and discharging of an energy storage converter. According to the voltage variation characteristics of a charging / discharging object during the charging / discharging process, the current voltage value of the charging / discharging object during the charging / discharging process is collected in real time or periodically, and the highest charging / discharging efficiency corresponding to the current voltage value is obtained according to a charging / discharging efficiency table, and then the corresponding ratio of required power to rated power is obtained according to the highest charging / discharging efficiency; then, the required power of the energy storage converter during charging / discharging is calculated according to the obtained ratio of required power to rated power, and the required power is synchronously adjusted to the actual power of the energy storage converter during charging / discharging, so that the energy storage converter operates at the highest charging / discharging efficiency corresponding to the current voltage value of the charging / discharging object throughout the charging / discharging process, thereby improving the charging / discharging efficiency and reducing the energy loss during the charging / discharging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 It is a principle block diagram of a charge and discharge control system of an energy storage converter provided by an embodiment of the present invention;

[0029] Figure 2 It is a schematic flow chart of the steps of a method for controlling charging and discharging of an energy storage converter provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following descriptions of the embodiments refer to the attached drawings to illustrate specific embodiments in which the present invention can be implemented.

[0031] The present invention provides a charge and discharge control system for an energy storage converter, the structure of which is as follows: Figure 1 As shown, it includes a charge / discharge efficiency table, a communication module, a voltage monitoring module, a query module, a calculation module and an adjustment module, wherein the charge / discharge efficiency table records the maximum charge / discharge efficiency of the energy storage converter corresponding to different voltage values ​​of the charge / discharge object during the charge / discharge process and the ratio of the required power to the rated power of the energy storage converter when charging / discharging; the communication module establishes a communication connection with the energy storage converter, and is used to send the received background charge / discharge instruction to the energy storage converter, and the energy storage converter charges and discharges the charge / discharge object according to the received charge / discharge instruction; the voltage monitoring module is used to monitor the current voltage value of the charge / discharge object in real time or periodically during the charge / discharge process. Specifically, the voltage monitoring module The invention is a voltage sensor; the query module establishes communication or electrical connection with the charge / discharge efficiency table and the voltage monitoring module respectively, so as to query the charge / discharge efficiency table to obtain the maximum charge / discharge efficiency corresponding to the current voltage value of the charge / discharge object and the ratio of the required power corresponding to the maximum charge / discharge efficiency to the rated power; the calculation module establishes communication or electrical connection with the query module, so as to calculate the required power of the energy storage converter when charging / discharging according to the obtained ratio of the required power to the rated power; the adjustment module establishes communication or electrical connection with the calculation module and the energy storage converter respectively, so as to simultaneously adjust the actual power of the energy storage converter when charging / discharging according to the calculated required power of the energy storage converter when charging / discharging.

[0032] The present invention provides a method for controlling charging and discharging of an energy storage converter, the steps of which are as follows: Figure 2 As shown, the following steps are included:

[0033] S1: Obtaining a charge / discharge efficiency table of the energy storage converter, wherein the charge / discharge efficiency table includes the maximum charge / discharge efficiency of the energy storage converter corresponding to different voltage values ​​of the charge / discharge object during the charge / discharge process and the ratio of the actual power to the rated power of the energy storage converter during the charge / discharge process;

[0034] S2: After receiving the charge / discharge instruction from the background, the energy storage converter starts to charge / discharge the charge / discharge object;

[0035] S3: During the charging / discharging process, the current voltage value of the charging / discharging object is monitored in real time or periodically, and the maximum charging / discharging efficiency corresponding to the current voltage value is obtained according to the charging / discharging efficiency table, and then the corresponding required power and rated power ratio is obtained according to the maximum charging / discharging efficiency;

[0036] S4: Calculate the required power of the energy storage converter when charging / discharging according to the ratio of the required power to the rated power, and adjust it to the actual power of the energy storage converter when charging / discharging, so that the energy storage converter operates at the highest charging / discharging efficiency corresponding to the current voltage value of the charging / discharging object during the charging / discharging process.

[0037] According to an embodiment of the present invention, in step S2, after the energy storage converter receives the charge / discharge instruction, before starting to charge / discharge the charge / discharge object, it also includes:

[0038] Obtaining an initial voltage value of the charge / discharge object, querying a charge / discharge efficiency table to obtain a maximum charge / discharge efficiency corresponding to the initial voltage value, and querying the charge / discharge efficiency table again to obtain a ratio of actual power to rated power of the energy storage converter during charging / discharging corresponding to the maximum charge / discharge efficiency;

[0039] The initial power when the energy storage converter starts charging / discharging is calculated according to the ratio of the actual power to the rated power, and the energy storage converter starts charging / discharging the charging / discharging object with the calculated initial power.

[0040] Specifically, taking a battery pack as the charging / discharging object as an example, the energy storage converter provided by the present invention performs the following process when charging / discharging the battery pack:

[0041] In the first step, a power analyzer is used to obtain a charge / discharge efficiency table of the energy storage inverter when charging / discharging the battery pack by multiple measurements at different voltage points on the DC side of the energy storage power station system and the power points of the energy storage inverter. The charge / discharge efficiency table of a certain type of energy storage inverter is shown in Table 1, which records the maximum charge / discharge efficiency of the energy storage inverter corresponding to different voltage values ​​of the battery pack during the charge / discharge process and the ratio of the required power to the rated power of the energy storage inverter when charging / discharging. Specifically, different specifications and models of energy storage inverters correspond to different charge / discharge efficiency tables, and energy storage inverters of the same specifications and models can share one charge / discharge efficiency table.

[0042] It can also be seen from Table 1 that at the same voltage point of the battery pack, the efficiency of energy storage inverters of the same specifications and models differs by 1%-3% when charged / discharged at different powers. In a charge / discharge cycle, the difference in charge / discharge efficiency can reach 2%-6%. In addition, low-efficiency charging / discharging will generate more heat (when working at low efficiency, a larger proportion of electrical energy will be converted into thermal energy; when working at high efficiency, the proportion of electrical energy converted into thermal energy is relatively reduced), and additional heat dissipation equipment is required, which will consume more energy.

[0043] It should be noted that Table 1 only shows the maximum charge / discharge efficiency of the energy storage converter and the ratio of the required power to the rated power of the energy storage converter when charging / discharging the battery pack for the three voltage values ​​(700V, 800V, 900V) during charging / discharging. In actual charging / discharging, since the voltage value of the battery pack is continuous and constantly changing, the actual charge / discharge efficiency table should provide more voltage values, such as 698V, 699V, 700V, 701V, 702V, ..., 800V, 801V, ..., and the division value between adjacent voltage values ​​should be as small as possible, such as 700V, 70 0.1V, 700.2V, ..., 701V, so that when looking up the table, the voltage value of the collected battery pack and the maximum charge / discharge efficiency of the energy storage converter corresponding to the voltage value and the ratio of the required power to the rated power of the energy storage converter when charging / discharging can be obtained directly from the charge / discharge efficiency table as much as possible. For example, when the collected voltage value is 710V, 715V, 720.02V, and 745.37V, the charge / discharge efficiency table records the above voltage values. In this way, the maximum charge / discharge efficiency of the energy storage converter corresponding to the above voltage value and the ratio of the required power to the rated power when the energy storage converter is charged / discharged can be directly looked up in the table. In addition, even if it is not possible to directly find the maximum charge / discharge efficiency of the energy storage converter corresponding to the collected voltage value and the ratio of the required power to the rated power when the energy storage converter is charged / discharged from the charge / discharge efficiency table, a charge / discharge efficiency table with more voltage data and smaller voltage division value can obtain more accurate data when using the interpolation method.

[0044] Table 1 Charging / discharging efficiency of a certain type of energy storage converter

[0045]

[0046]

[0047] Step 2: After receiving the charge / discharge instruction from the background, the communication module sends the charge / discharge instruction to the energy storage converter. After receiving the charge / discharge instruction, the energy storage converter collects the initial voltage value of the battery pack to be charged / discharged through the voltage sensor. The query module queries the charge / discharge efficiency table to obtain the highest charge / discharge efficiency corresponding to the initial voltage value, and queries the charge / discharge efficiency table again to obtain the ratio of the required power to the rated power of the energy storage converter corresponding to the highest charge / discharge efficiency when charging / discharging.

[0048] In step 3, the calculation module calculates the initial power required for the energy storage converter to start charging / discharging according to the ratio of the actual power to the rated power, and the energy storage converter starts charging / discharging the battery pack with the calculated initial power.

[0049] Step 4: During the charging and discharging process of the battery pack, the voltage sensor monitors the current voltage value of the battery pack in real time or periodically, and obtains the maximum charge / discharge efficiency corresponding to the current voltage value according to the charge / discharge efficiency table, and then obtains the corresponding required power to rated power ratio according to the maximum charge / discharge efficiency;

[0050] Among them, when obtaining the highest charge / discharge efficiency corresponding to the current voltage value according to the charge / discharge efficiency table, and obtaining the corresponding required power to rated power ratio according to the highest charge / discharge efficiency, the linear interpolation method can be used to obtain the highest charge / discharge efficiency corresponding to the current voltage value and not recorded in the charge / discharge efficiency table, and the ratio of the required power of the energy storage converter corresponding to the highest charge / discharge efficiency to rated power. Since linear interpolation is a simple interpolation method widely used in mathematics, computer graphics and other fields, and belongs to the prior art, the process of how to use the linear interpolation method to obtain parameter data not recorded in the charge / discharge efficiency table is not described in detail in this embodiment.

[0051] In step 5, the calculation module calculates the required power of the energy storage converter when charging / discharging according to the ratio of the required power to the rated power, and the adjustment module simultaneously adjusts it to the actual power of the energy storage converter when charging / discharging, so that the energy storage converter operates at the highest charging / discharging efficiency corresponding to the current voltage value of the charging / discharging object throughout the charging / discharging process.

[0052] In summary, the present invention provides a method and system for controlling charging and discharging of an energy storage converter. According to the characteristics of voltage change of a charging / discharging object during the charging / discharging process, the current voltage value of the charging / discharging object during the charging / discharging process is collected in real time or periodically, and the maximum charging / discharging efficiency corresponding to the current voltage value is obtained according to a charging / discharging efficiency table, and then the corresponding ratio of required power to rated power is obtained according to the maximum charging / discharging efficiency; then, the required power of the energy storage converter during charging / discharging is calculated according to the obtained ratio of required power to rated power, and the required power is synchronously adjusted to the actual power of the energy storage converter during charging / discharging, so that the energy storage converter operates at the highest charging / discharging efficiency corresponding to the current voltage value of the charging / discharging object throughout the charging / discharging process, thereby improving the charging / discharging efficiency and reducing energy loss during the charging / discharging process.

[0053] It should be noted that although the present invention is disclosed as above by specific embodiments, the above embodiments are not intended to limit the present invention. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for controlling charging and discharging of an energy storage converter, characterized in that: The following steps are involved: S1: Obtaining a charge / discharge efficiency table of the energy storage converter, wherein the charge / discharge efficiency table includes the maximum charge / discharge efficiency of the energy storage converter corresponding to different voltage values ​​of the charge / discharge object during the charge / discharge process and the ratio of the actual power to the rated power of the energy storage converter during the charge / discharge process; S2: After receiving the charge / discharge instruction from the background, the energy storage converter starts to charge / discharge the charge / discharge object; S3: During the charging / discharging process, the current voltage value of the charging / discharging object is monitored in real time or periodically, and the maximum charging / discharging efficiency corresponding to the current voltage value is obtained according to the charging / discharging efficiency table, and then the corresponding required power and rated power ratio is obtained according to the maximum charging / discharging efficiency; S4: Calculate the required power of the energy storage converter when charging / discharging according to the ratio of the required power to the rated power, and adjust it to the actual power of the energy storage converter when charging / discharging, so that the energy storage converter operates at the highest charging / discharging efficiency corresponding to the current voltage value of the charging / discharging object during the charging / discharging process.

2. A method for controlling charging and discharging of an energy storage converter according to claim 1, characterized in that: In step S2, after the energy storage converter receives the charge / discharge instruction, before starting to charge / discharge the charge / discharge object, it also includes: Obtaining an initial voltage value of the charge / discharge object, querying a charge / discharge efficiency table to obtain a maximum charge / discharge efficiency corresponding to the initial voltage value, and querying the charge / discharge efficiency table again to obtain a ratio of actual power to rated power of the energy storage converter during charging / discharging corresponding to the maximum charge / discharge efficiency; The initial power when the energy storage converter starts charging / discharging is calculated according to the ratio of the actual power to the rated power, and the energy storage converter starts charging / discharging the charging / discharging object with the calculated initial power.

3. A method for controlling charging and discharging of an energy storage converter according to any one of claims 1 or 2, characterized in that: The initial voltage value and the current voltage value are both acquired through the voltage sensor.

4. The energy storage converter charge and discharge control method according to claim 1, characterized in that: In step S3, when obtaining the highest charge / discharge efficiency corresponding to the current voltage value according to the charge / discharge efficiency table, and obtaining the corresponding ratio of actual power to rated power according to the highest charge / discharge efficiency, linear interpolation method is used to obtain the highest charge / discharge efficiency corresponding to the current voltage value and not recorded in the charge / discharge efficiency table, and the ratio of actual power to rated power of the energy storage converter corresponding to the highest charge / discharge efficiency.

5. The energy storage converter charge and discharge control method according to claim 1, characterized in that: The charge / discharge efficiency table of the energy storage converter is obtained by multiple measurements with a power analyzer at different voltage points on the DC side of the energy storage power station system and at different power points of the energy storage converter.

6. The energy storage converter charge and discharge control method according to claim 1, characterized in that: The charging / discharging object is a battery pack.

7. A charge and discharge control system for an energy storage converter, characterized in that: include: The charge / discharge efficiency table records the maximum charge / discharge efficiency of the energy storage converter corresponding to different voltage values ​​of the charge / discharge object during the charge / discharge process and the ratio of the required power to the rated power of the energy storage converter during charge / discharge; The communication module establishes a communication connection with the energy storage converter, and is used to send the received background charge / discharge instruction to the energy storage converter, and the energy storage converter charges / discharges the charge / discharge object according to the received charge / discharge instruction; A voltage monitoring module is used to monitor the current voltage value of the charging / discharging object in real time or periodically during the charging / discharging process; a query module, establishing communication or electrical connection with the charge / discharge efficiency table and the voltage monitoring module respectively, for querying the charge / discharge efficiency table to obtain the maximum charge / discharge efficiency corresponding to the current voltage value of the charge / discharge object and the ratio of the required power corresponding to the maximum charge / discharge efficiency to the rated power; A calculation module, which establishes communication or electrical connection with the query module, and is used to calculate the required power of the energy storage converter when charging / discharging according to the ratio of the required power to the rated power; The adjustment module establishes communication or electrical connection with the calculation module and the energy storage converter respectively, so as to adjust the actual power of the energy storage converter during charging / discharging synchronously with the calculated required power of the energy storage converter during charging / discharging.

8. The energy storage converter charge and discharge control system according to claim 7, characterized in that: The voltage monitoring module is a voltage sensor.

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