CN117748685A

CN117748685A - Charging control method of power supply circuit, power supply equipment and energy storage equipment

Info

Publication number: CN117748685A
Application number: CN202410086637.0A
Authority: CN
Inventors: 刘万启; 李亚贵; 王雷; 陈熙
Original assignee: Ecoflow Technology Ltd
Current assignee: Ecoflow Technology Ltd
Priority date: 2024-01-20
Filing date: 2024-01-20
Publication date: 2024-03-22

Abstract

The application provides a charging control method of a power supply circuit, power supply equipment and energy storage equipment. The power supply circuit is arranged in a power supply system comprising a battery pack, direct current power generation equipment, an inverter and a power supply circuit. The method comprises the following steps: in each operation period, obtaining reserved power of an inverter in the last operation period, actual power generation power of direct current power generation equipment and a power fluctuation coefficient; determining the reserved power of the current operation period according to the reserved power of the previous operation period and the power fluctuation coefficient; determining the upper limit of charging power according to the actual power generation power and the reserved power of the current operation period; performing amplitude limiting processing on target charging power of the power supply circuit according to the upper limit of the charging power; and acquiring electric energy from the direct current bus according to the target charging power after the amplitude limiting treatment to charge the battery pack. The method provided by the application can be adapted to different inverters and different working conditions to update the reserved power, so that the normal operation of the inverters is ensured when the battery pack is charged.

Description

Charging control method of power supply circuit, power supply equipment and energy storage equipment

Technical Field

The application relates to the technical field of electronic equipment, in particular to a charging control method of a power supply circuit, power supply equipment and energy storage equipment.

Background

Photovoltaic power generation technology is a technology that converts solar energy into electrical energy to power a load. In the related art, in order to fully utilize solar energy resources, a photovoltaic system utilizes an inverter to convert direct current generated by a photovoltaic module into alternating current for load use, and meanwhile, the photovoltaic system also utilizes an energy storage device to store redundant energy which is supplied by the photovoltaic module outside the load, so that the energy storage device is controlled to provide energy for the load for use through the photovoltaic inverter when the solar energy resources are insufficient.

In the photovoltaic system, when the energy storage device is charged to store energy generated by the photovoltaic module, a certain reserved power is required to maintain the basic operation of the inverter, for example, to realize the maximum power tracking function. While the reserved power may be different for different inverters. The reserved power of the same inverter can be different under the condition of different voltage and current. In the related art, a single reserved power is generally employed. Therefore, when the reserved power is more, the power waste is caused, and when the reserved power is less, the situation that some inverters or the inverters cannot work stably under certain working conditions can occur, so that the voltage fluctuation of the photovoltaic module is aggravated.

Disclosure of Invention

In view of this, the present application provides a charging control method for a power supply circuit, a power supply device, and an energy storage device, which can adapt to different inverters and different working conditions to update the reserved power, so as to ensure the normal operation of the inverters when charging a battery pack.

The first aspect of the present application provides a charging control method for a power supply circuit, where the power supply circuit is disposed in a power supply system, and the power supply system includes a battery pack, a dc power generation device, an inverter, and a power supply circuit. The first end of the power supply circuit is used for connecting the battery pack. The second end of the power supply circuit, the output end of the direct current power generation equipment and the direct current input end of the inverter are all connected to the direct current bus; the method comprises the following steps: in each operation period, obtaining reserved power of an inverter in the last operation period, actual power generation power of direct current power generation equipment and a power fluctuation coefficient; the power fluctuation coefficient is used for representing the fluctuation degree of the actual power generation power; determining the reserved power of the current operation period according to the reserved power of the previous operation period and the power fluctuation coefficient; determining the upper limit of charging power according to the actual power generation power and the reserved power of the current operation period; performing amplitude limiting processing on target charging power of the power supply circuit according to the upper limit of the charging power; and acquiring electric energy from the direct current bus according to the target charging power after the amplitude limiting treatment to charge the battery pack.

In one embodiment, the method further comprises: acquiring a plurality of actual power generation powers of the DC power generation equipment acquired within a preset time period; calculating average value and average variance of a plurality of actual power generation powers acquired in a preset time period; and determining the power fluctuation coefficient according to the average variance and the average value.

In one embodiment, determining the power fluctuation coefficient from the average variance and the average value includes: the ratio of the average variance to the square of the average is calculated as the power fluctuation coefficient.

In an embodiment, determining the reserved power of the current operation period according to the reserved power of the previous operation period and the power fluctuation coefficient includes: determining an adjustment coefficient according to the power fluctuation coefficient and the power fluctuation coefficient reference value, wherein the power fluctuation coefficient and the adjustment coefficient are in positive correlation; determining a power adjustment step length according to the adjustment coefficient and the reference step length, wherein the power adjustment step length and the power adjustment coefficient are in positive correlation; and determining the reserved power of the current operation period according to the reserved power of the last operation period and the power adjustment step length.

In an embodiment, determining the upper limit of the charging power according to the actual generated power and the reserved power of the current operation period includes calculating a difference between the actual generated power and the reserved power of the current operation period as the upper limit of the charging power.

In one embodiment, clipping the target charging power of the power supply circuit according to the charging power upper limit includes: acquiring target charging power of a power supply circuit; when the target charging power is greater than the upper charging power limit, adjusting the target charging power to the upper charging power limit; when the target charging power is not greater than the charging power upper limit, the target charging power is not adjusted.

In an embodiment, the ac output of the inverter is connected to the power grid via an ac bus, the method further comprising: acquiring actual grid-connected power between an alternating current bus and a power grid; and determining the target charging power of the power supply circuit according to the actual grid-connected power and the target grid-connected power.

In one embodiment, the method further comprises: periodically collecting the sampling output power of the direct current power generation equipment; and filtering the sampled output power to obtain the actual power generation power.

A second aspect of the present application provides a power supply apparatus including a power supply circuit and a controller. The power supply equipment is arranged on the power supply system. The power supply system comprises a battery pack, direct current power generation equipment, an inverter and a power supply circuit. The first end of the power supply circuit is used for being connected with the battery pack, and the second end of the power supply circuit, the output end of the direct current power generation equipment and the direct current input end of the inverter are all connected to the direct current bus. The controller is configured to execute the charge control method of the power supply circuit according to any one of the above.

A third aspect of the present application provides an energy storage device comprising a power supply circuit, a battery pack, and a controller. The energy storage device is arranged on the power supply system. The power supply system comprises energy storage equipment, direct current power generation equipment and an inverter. The first end of the power supply circuit is used for being connected with the battery pack, and the second end of the power supply circuit, the output end of the direct current power generation equipment and the direct current input end of the inverter are all connected to the direct current bus. The controller is configured to execute the charge control method of the power supply circuit according to any one of the above.

In summary, in each operation cycle, the charging control method for the power supply circuit provided by the present application first obtains the reserved power of the inverter in the previous operation cycle, the actual power generation power of the dc power generation device, and the power fluctuation coefficient. And determining the reserved power of the current operation period according to the reserved power of the previous operation period and the power fluctuation coefficient. The reserved power is used for representing the fluctuation degree of the actual power generation power, and therefore the reserved power can influence the power fluctuation coefficient. Therefore, the reserved power of the previous operation period can be adjusted according to the power fluctuation coefficient to obtain the reserved power of the current operation period, so that on one hand, the reserved power of the current operation period can maintain the MPPT function of the inverter and reduce the wasted power; on the other hand, the reserved power is updated in each operation period, so that the reserved power can be adapted to different inverters and different working conditions. And then determining an upper limit of the charging power according to the actual power generation power and the reserved power, and limiting the target charging power of the power supply circuit according to the upper limit of the charging power so as to acquire electric energy from the direct current bus according to the target charging power to charge the battery pack. Therefore, enough reserved power of the inverter can be ensured, so that the working stability of the power supply system is improved, and the spontaneous self-use of the power supply system is realized.

Drawings

In order to more clearly illustrate the technical solutions of the present application, the drawings that are required for the embodiments will be briefly described, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope of protection of the present application. Like elements are numbered alike in the various figures.

Fig. 1 is a block diagram of a power supply system according to an embodiment of the present application.

Fig. 2 is a flow chart of a charging control method of a power supply circuit according to an embodiment of the present application.

Fig. 3 is a flow chart of acquiring actual generated power in a method for controlling charging of a power supply circuit according to an embodiment of the present application.

Fig. 4 is a flow chart of the sub-steps of step S202 in an embodiment of the present application.

Fig. 5 is a flow chart of the sub-steps of step S204 in an embodiment of the present application.

Fig. 6 is a flowchart of determining a target charging power in a charging control method of a power supply circuit according to an embodiment of the present application.

Fig. 7 is a flow chart of acquiring actual generated power in a method for controlling charging of a power supply circuit according to an embodiment of the present application.

Fig. 8 is a control block diagram of a charging control method of a power supply circuit in an embodiment of the present application.

Fig. 9 is a functional block diagram of a power supply device according to an embodiment of the present application.

Fig. 10 is a functional block diagram of an energy storage device according to an embodiment of the present application.

Fig. 11 is a functional block diagram of a control device according to an embodiment of the present application.

Detailed Description

The following description of the technical solutions in the embodiments of the present application will be made with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments.

It is noted that when one component is considered to be "connected" to another component, it may be directly connected to the other component or intervening components may also be present. When an element is referred to as being "disposed" on another element, it can be directly on the other element or intervening elements may also be present. The terms "top," "bottom," "upper," "lower," "left," "right," "front," "rear," and the like are used herein for illustrative purposes only.

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

Some embodiments will be described below with reference to the accompanying drawings. The following embodiments and features of the embodiments may be combined with each other without conflict.

Photovoltaic power generation technology is a technology that converts solar energy into electrical energy to power a load. In the related art, in order to fully utilize solar energy resources, a photovoltaic system converts direct current generated by a photovoltaic module into alternating current by using an inverter, such as a photovoltaic inverter or an energy storage converter, for use by a load, and simultaneously, the photovoltaic system also stores surplus energy supplied by the photovoltaic module to the load by using an energy storage device, so as to control the energy storage device to supply energy to the load through the inverter for use when the solar energy resources are insufficient.

For example, referring to fig. 1, fig. 1 is a schematic diagram of a power supply system 10 according to an embodiment of the present application. The power supply system 10 includes a battery pack 110, a power supply circuit 120, a dc power generation device 130, and an inverter 140. The first end of the power supply circuit 120 is configured to be connected to the battery pack 110, and the second end of the power supply circuit 120, the output end of the DC power generation device 130, and the DC input end of the inverter 140 are all connected to DC buses (including a positive DC BUS dc_bus+ and a negative DC BUS dc_bus-). The output of inverter 140 is connected to grid 20 via an ac bus (including neutral N and hot L). The ac bus is also connected to a load 30.

Further, one or more series and/or parallel cells are disposed within the battery pack 110. The battery pack 110 is used to store or release energy.

The power supply circuit 120 includes a direct current-to-direct current (Direct Current to Direct Current, DC/DC) conversion unit. The DC/DC conversion unit is configured to boost and buck the battery voltage of the battery pack 110 and then discharge the battery voltage through the DC bus, or boost and buck the charging voltage provided by the DC bus and then charge the battery pack 110. Specifically, when the power supply circuit 120 is charged, power is taken from the direct current power generation device 130 through the direct current bus for power conversion so as to charge the battery pack 110; the power supply circuit 120 receives power from the battery pack 110 and outputs the power to the dc bus when discharging.

It is understood that the DC/DC conversion unit may be composed of a BUCK circuit, a BOOST circuit, or a BUCK-BOOST circuit. Thus, by controlling the switching logic and the duty ratio of the BUCK circuit, the BOOST circuit or the BUCK-BOOST circuit, the DC/DC conversion unit can be controlled to operate in a charging mode or a discharging mode, and the output power of the DC/DC conversion unit can be controlled. In other embodiments, the DC/DC conversion unit may include DAB (Dual Active Bridge, double active bridge) circuitry, as well as boost circuitry and LLC Series-parallel resonant (LLC Series-parallel resonant) circuitry. The specific circuit structures of the boost circuit, the DAB circuit, and the LLC circuit are not limited herein.

The dc power generation device 130 includes a number of photovoltaic panels. The photovoltaic panel outputs direct current to the inverter 140 by converting light energy into electrical energy and/or charges the battery pack 110 through the power supply circuit 120. It is understood that the present application is not limited to the manner in which photovoltaic panels are connected in the dc power generation facility 130. For example, in some embodiments, the photovoltaic panels in the dc power generation device 130 may be connected in series, in parallel, or connected in series followed by parallel, etc.

The inverter 140 at least includes a direct current to alternating current (Direct Current to Alternating Current, DC/AC) conversion unit to convert the direct current of the DC power generation device 130 and/or the power supply circuit 120, which is obtained from the direct bus, into alternating current, and output the alternating current to the AC bus to supply power to the load 30 and/or to the power grid 20. It is to be understood that the present application is not limited to a specific circuit configuration of the DC/AC converting unit, and for example, the DC/AC converting unit may be a full-bridge topology, a half-bridge topology, or the like. In some embodiments, the inverter 140 may also include a maximum power tracking (Maximum Power Point Tracking, MPPT) circuit to enable maximum power tracking of the photovoltaic power plant due to the power generation characteristics of the dc power plant 130 as the photovoltaic power plant.

The power grid 20 may be, for example, a utility power grid. It is understood that the present application is not limited to the type of ac power of the power grid 20, and in other embodiments, the power grid 20 may be single-phase ac power, three-phase ac power, or other multi-phase ac power, etc. The load 30 may be various kinds of electric loads in the home, or may be an important load.

In the photovoltaic system, when the energy storage device (e.g., the battery pack 110) is charged to store energy generated by the photovoltaic module (i.e., the dc power generation device 130), a certain reserved power is required in order to maintain the basic operation of the inverter, for example, to implement the maximum power tracking function. While the reserved power may be different for different inverters. The reserved power of the same inverter can be different under the condition of different voltage and current. In the related art, a single reserved power is generally employed. Therefore, when the reserved power is more, the power waste is caused, and when the reserved power is less, the situation that some inverters or the inverters cannot work stably under certain working conditions can occur, so that the voltage fluctuation of the photovoltaic module is aggravated.

Therefore, the application provides a charging control method of a power supply circuit, which can update reserved power in real time according to the fluctuation degree of the actual power generation power of direct current power generation equipment, so that the reserved power can be adapted to different inverters and different working conditions. It is to be understood that the charging control method of the power supply circuit provided in the present application may be applied to the power supply system 10 shown in fig. 1. And the charge control method of the power supply circuit may be performed by the controller of the power supply circuit 120. Referring to fig. 2, the control method includes the following steps:

Step S201: in each operation period, obtaining reserved power of an inverter in the last operation period, actual power generation power of direct current power generation equipment and a power fluctuation coefficient; the power fluctuation coefficient is used for representing the fluctuation degree of the actual generated power.

The operation period may be set according to actual requirements, for example, the operation period may be an operation period of a controller of the power supply circuit 120.

Reserve power is used to ensure basic operation of inverter 140, such as maintaining MPPT functionality for dc power generation device 130. The reserved power is greater than or equal to the lowest power consumption when the inverter 140 maintains normal operation. In the first operation period, the reserved power initial value can be obtained as the reserved power of the previous operation period. The reserved power initial value may be data obtained based on a plurality of inverter tests in a laboratory, for example, the reserved power initial value may be 600W. In other embodiments, the reserved power initial value may be reserved power preset by different inverters.

The actual generated power is used to represent the power output by the dc power generation device 130 to the dc bus. The actual generated power is used to charge the battery pack 110 through the power supply circuit 120 and/or to power the load 30 through the inverter 140. Also, inverter 140 needs to draw at least reserve power from the dc bus to maintain the MPPT function. That is, at least a part of the actual generated power is used as the reserve power of the inverter 140.

Understandably, by processing the actual generated power, the power fluctuation coefficient can be calculated. It will be appreciated that when the environment in which the dc power generation device 130 is located changes, the actual power generated by the dc power generation device 130 may also change, and the reserved power required by the inverter 140 may also change. Therefore, whether the reserved power is reasonable or not can be judged according to the calculated power fluctuation coefficient.

Step S202: and determining the reserved power of the current operation period according to the reserved power of the previous operation period and the power fluctuation coefficient.

Since the reserve power is used to maintain the MPPT function of the inverter 140, if the reserve power is too low to maintain the MPPT function, the voltage of the dc power generation device 130 may fluctuate uncontrollably based on the operating characteristics of the photovoltaic panel, thereby causing severe fluctuation in the actual generated power. And if the reserve power is too high, although this may make the degree of fluctuation of the actual generated power low, energy waste is caused. And because the power fluctuation coefficient is used for representing the fluctuation degree of the actual power generation power, the influence of the reserved power of the previous operation period on the actual power generation power can be determined by observing the size of the power fluctuation coefficient.

That is, the magnitude of the reserve power affects the magnitude of the power fluctuation coefficient in each operation cycle, and it is necessary to determine an appropriate reserve power, while reducing the fluctuation degree of the actual generated power as much as possible.

In this way, in step S202, the reserved power of the previous operation period may be adjusted according to the power fluctuation coefficient to obtain the reserved power of the current operation period. For example, when the value of the power fluctuation coefficient indicates that the fluctuation degree of the actual generated power is small, the reserved power of the previous operation period is reduced to determine the reserved power of the current operation period, thereby reducing the energy waste. When the value of the power fluctuation coefficient indicates that the fluctuation degree of the actual power generation power is large, the reserved power of the previous operation period is increased to determine the reserved power of the current operation period, so that the actual power generation power is stabilized.

Step S203: and determining the upper limit of the charging power according to the actual power generation power and the reserved power of the current operation period.

The upper limit of the charging power is used to characterize the maximum charging power of the power supply circuit 120.

Referring again to fig. 1, when the power supply circuit 120 charges, the power supply circuit 120 obtains energy from the dc bus to charge the battery pack 110. Meanwhile, as can be seen from the above, the inverter 140 also needs to obtain at least the reserved power from the dc bus to maintain the MPPT function. At this time, the energy on the dc bus is provided by the dc power generation device 130. As such, the power supply circuit 120 cannot obtain the entire actual generated power, and also needs to reserve the reserved power for the inverter 140 to obtain. Therefore, in step S203, the upper limit of the charging power of the power supply circuit 120 is determined according to the actual generated power and the reserved power of the current operation period, so as to avoid the situation that the reserved power of the inverter 140 is insufficient due to the power supply circuit 120 obtaining excessive power from the dc bus.

Step S204: and performing amplitude limiting processing on the target charging power of the power supply circuit according to the upper limit of the charging power.

Wherein the target charging power is used to characterize the ideal charging power of the power supply circuit 120.

In step S204, the target charging power after the clipping process is made smaller than or equal to the charging power upper limit by performing the clipping process on the target charging power.

Step S205: and acquiring electric energy from the direct current bus according to the target charging power after the amplitude limiting treatment to charge the battery pack.

Understandably, by executing step S205, it is ensured that the inverter 140 has enough reserve power while ensuring the normal charging of the power supply circuit 120, so as to reduce the fluctuation of the actual generated power and improve the stability of the operation of the power supply system 10.

In this way, the controller cyclically performs steps S201 to S205 for each operation cycle to update the reserve power for each operation cycle, and determines the target charging power of the power supply circuit according to the reserve power. In this way, a timed refresh of the reserve power of the inverter 140 and the target charging power of the power supply circuit 120 can be achieved, and its refresh frequency depends on the operating cycle of the controller.

In summary, in each operation cycle, the charging control method for the power supply circuit provided by the present application first obtains the reserved power of the inverter in the previous operation cycle, the actual power generation power of the dc power generation device, and the power fluctuation coefficient. And determining the reserved power of the current operation period according to the reserved power of the previous operation period and the power fluctuation coefficient. The reserved power is used for representing the fluctuation degree of the actual power generation power, and therefore the reserved power can influence the power fluctuation coefficient. Thus, the reserved power of the previous operation period can be adjusted according to the power fluctuation coefficient to obtain the reserved power of the current operation period, so that on one hand, the reserved power of the current operation period can maintain the MPPT function of the inverter 140 and reduce the wasted power; on the other hand, the reserved power is updated in each operation period, so that the reserved power can be adapted to different inverters 140 and different working conditions. And then, determining an upper limit of the charging power according to the actual power generation power and the reserved power, and limiting the target charging power of the power supply circuit according to the upper limit of the charging power so as to acquire electric energy from the direct current bus according to the target charging power to charge the battery pack 110. In this way, the inverter 140 can be ensured to have enough reserved power to maintain normal operation, so that the stability of the operation of the power supply system 10 is improved, and the spontaneous self-use of the power supply system 10 is realized.

Referring to fig. 3, in some embodiments, the control method further includes:

step S301: and acquiring a plurality of actual power generation powers of the DC power generation equipment acquired within a preset time period.

In some embodiments, the actual generated power of the direct current power generation device may be periodically collected. And then obtaining a plurality of actual power generation powers in a preset time period.

The specific duration of the preset duration is not limited in the application.

Step S302: and calculating the average value and the average variance of a plurality of actual generated power acquired in a preset time period.

It can be understood that the plurality of actual power generation powers collected in the preset time period can be added to obtain a sum of the actual power generation powers in the time period, and the sum is divided by the number of the actual power generation powers collected in the preset time period to obtain an average value of the plurality of actual power generation powers collected in the preset time period.

It is understood that the squares of the differences between each actual generated power and the average value within the preset time period are calculated respectively, and then the average value of the squares of the multiple sets of differences is calculated to obtain the average variance.

In some embodiments, a moving average algorithm is used to average and average the variance over a predetermined period of time. The basic principle of the sliding average algorithm is that N actual power generation powers are sequentially obtained, and an average value of all current actual power generation powers is output if the obtained actual power generation powers are less than N; when the obtained actual power exceeds N, the output is equal to the average value of the obtained N actual power. The moving average algorithm can effectively eliminate periodic interference and partial irregular interference. Correspondingly, the average variance of the obtained N actual power generation powers can be calculated corresponding to a moving average algorithm.

The application is not limited to the parameters (e.g., specific values of N) in the sliding average algorithm employed.

Step S303: and determining the power fluctuation coefficient according to the average variance and the average value.

Understandably, the average variance is used to represent the average of the sum of squares of the differences of each actual generated power from the average of the actual generated power. That is, the average variance is used to characterize the degree to which the plurality of actual generated powers obtained within the preset time period deviate from the average value of the actual generated powers. Therefore, in step S303, the power fluctuation coefficient may be determined according to the average variance and the average value.

In some embodiments, step S303 comprises:

the ratio of the average variance to the square of the average is calculated as the power fluctuation coefficient.

For example, the power fluctuation coefficient may be determined according to the following equation (1) and equation (2):

wherein VAR is as follows _{p_pv} Is the mean variance; p (P) _{PV_avr} The average value of a plurality of actual power generation powers obtained in a preset time period is obtained; p (P) _pv (n) is the actual generated power collected; n represents the nth actual generated power within a preset time period; n represents the total amount of the actual generated power obtained in the preset time period; k is the power fluctuation coefficient; p (P) _{PV_avr} ² And the square of the average value of a plurality of actual generated powers obtained in the preset time period.

In other embodiments, the ratio of the value obtained after the mean variance is squared to the mean value may be used as the power fluctuation coefficient. The specific calculation process for calculating the power fluctuation coefficient is not limited in this application.

In summary, by performing steps S301 to S303, the power fluctuation coefficient in step S201 can be calculated.

Referring to fig. 4, in some embodiments, step S202 includes the following sub-steps:

step S401: and determining an adjustment coefficient according to the power fluctuation coefficient and the power fluctuation coefficient reference value, wherein the power fluctuation coefficient and the adjustment coefficient are in positive correlation.

The adjustment coefficient is used for representing the influence of the difference between the power fluctuation coefficient and the power fluctuation coefficient reference value on the actual generated power.

In some embodiments, the difference of the power fluctuation coefficient minus the power fluctuation coefficient reference value may be used as the adjustment coefficient.

Step S402: and determining a power adjustment step length according to the adjustment coefficient and the reference step length, wherein the power adjustment step length and the power adjustment coefficient are in positive correlation.

The reference step size may be a base step size each time the actual generated power is adjusted. The power adjustment step size is used to characterize the step size each time the actual generated power is adjusted.

In some embodiments, the product of the adjustment coefficient and the reference step size may be used as the power adjustment step size.

Step S403: and determining the reserved power of the current operation period according to the reserved power of the last operation period and the power adjustment step length.

In some embodiments, the value obtained by adding the reserved power of the previous operation period and the power adjustment step size may be used as the reserved power of the current operation period.

For example, in some embodiments, the reserved power for the current run period may be determined according to the following equation (4):

P ₂ ＝P ₁ +(k-s)*P _delta (4)

wherein P is ₂ Reserving power for a current operation period; p (P) ₁ Reserving power for a previous operation period; k is the power fluctuation coefficient; s is a power fluctuation coefficient reference value; p (P) _delta Is the reference step size.

It is understood that the present application is not limited to a specific calculation formula for determining the reserved power of the current operation period. For example, in other embodiments, the reserved power for the current run period may also be determined based on equation 5 as follows:

P ₂ ＝P ₁ +(k-s)*P _delta +a (5)

where a is an adjustment parameter determined from the power loss in the dc bus. In some embodiments, a may be a constant.

In summary, by performing steps 401 to S403, the reserved power of the current operation period can be calculated.

In some embodiments, step S203 includes:

and calculating the difference between the actual generated power and the reserved power of the current operation period as the upper limit of the charging power.

It is understood that, since the reserve power can be obtained by the inverter 140 from the dc bus, and the actual generated power of the dc power generation device 130 is output to the dc bus, the reserve power is provided by the actual generated power. Since the inverter 140 at least needs the reserved power to maintain the normal MPPT function, the difference between the actual generated power and the reserved power of the current operation period can be used as the upper limit of the charging power.

Referring to fig. 5, in some embodiments, step S204 includes:

step S501: the target charging power of the power supply circuit is obtained.

The target charging power is used to characterize an ideal value of the charging power of the power supply circuit 120. In some embodiments, the target charging power may be calculated based on a closed loop power control algorithm of the power supply system 10.

Step S502: and when the target charging power is greater than the upper charging power limit, adjusting the target charging power to the upper charging power limit.

Step S503: when the target charging power is not greater than the charging power upper limit, the target charging power is not adjusted.

In this manner, by performing the above steps S501 to S503, the target charging power can be made smaller than or equal to the charging power upper limit, thereby ensuring that at least the reserve power is available to the inverter 140.

Referring to fig. 6, in some embodiments, the control method further includes:

step S601: and acquiring actual grid-connected power between the alternating current bus and the power grid.

Referring again to fig. 1, it can be appreciated that when the output of inverter 140 is connected to grid 20 via an ac bus, it is referred to as grid-tie. The actual grid-tied power is used to represent the power supply relationship between the inverter 140 connected to the ac bus and the load 30 and the grid 20. For example, the actual grid-tied power may be positive, negative, or 0, depending on the inverter 140 and the direction of energy flow between the load 30 and the grid 20. For example, when the inverter 140 outputs 10W (watts) to the grid 20 through the ac bus, then the actual grid-tied power is 10W; when the power grid 20 outputs 10W to the alternating current bus to supply power for the load 30, the actual grid-connected power is-10W; when the output power of the inverter 140 just meets the required power of the load 30, that is, the inverter 140 outputs no power to the grid 20, and the grid 20 outputs no power to the load 30, the actual grid-connected power is 0.

It is understood that the definition of positive and negative numbers for actual grid-tied power is merely exemplary. In other embodiments, the grid may also be indicated to supply power to the load when the actual grid-tied power is positive, and the inverter 140 may be indicated to sell power to the grid 20 when the actual grid-tied power is negative.

In some embodiments, a grid monitoring module (not shown) may be provided between the local micro grid system consisting of the power supply system 10 and the load 30 and the grid 20, i.e. between the common connection point of the output of the inverter 140 and the load 30 and the grid 20. The grid monitoring module is used to monitor the grid-tie parameters between the ac bus and the grid 20. The grid-connected parameters may include grid-connected current, grid-connected voltage, actual grid-connected power, and the like. In this way, the controller of the power supply circuit 120 can obtain the actual grid-connected power output from the inverter 140 to the grid 20 or the grid 20 to the load 30 by communicating with the grid monitoring module. In some embodiments, the grid monitoring module may be a smart meter, such as a bi-directional power sensor, and the smart meter may transmit actual grid-tied power.

It is to be understood that the communication between the controller and the power grid monitoring module may be wireless communication (such as bluetooth communication, zigBee communication, etc.), or may be wired communication (such as serial communication based on RS-485 serial bus, or controller area network (Controller Area Network, CAN) bus, etc. or other parallel communication modes), which is not limited in this application.

In other embodiments, the controller may communicate with the inverter 140 and the load 30 to obtain the actual output power of the inverter 140 and the actual power consumption of the load 30, so as to calculate the actual grid-connected power according to the actual output power and the actual power consumption.

Step S602: and determining the target charging power of the power supply circuit according to the actual grid-connected power and the target grid-connected power.

The target grid-tie power is used to characterize an ideal value of the actual grid-tie power between the ac bus and the grid 20. For example, in some embodiments, the target grid-tie power is 0, at which point the power output by inverter 140 just meets the demand power of load 30. As such, the inverter 140 does not have to purchase electricity from the grid 20 nor sell electricity to the grid 20. In some embodiments, the target grid-tie power may also be negative or positive. The meaning of the target grid-connected power is negative or positive, which is substantially the same as the meaning of the actual grid-connected power is positive or negative, and will not be described in detail herein. It is understood that the present application does not limit the specific value of the target grid-tie power.

It will be appreciated that when the actual grid-tie power is greater than the target grid-tie power, it is indicated that the power output from the inverter 140 to the grid 20 is greater than expected at this time, and thus, a portion of the energy output from the dc power generation device 130 can be stored in the battery pack 110 by charging the battery pack 110. When the actual grid-connected power is smaller than the target grid-connected power, it indicates that the power output by the inverter 140 is insufficient to meet the requirement of the load 30, and the load 30 draws power from the power grid, so that the power supply circuit 120 can obtain the electric energy of the battery pack 110 and then discharge the electric energy to the dc bus, so as to increase the actual output power of the inverter 140 and reduce the power drawing from the power grid 20.

Thus, when the actual grid-connected power is greater than the target grid-connected power, the difference obtained by subtracting the target grid-connected power from the actual grid-connected power may be used as the target charging power, so as to control the power supply circuit 120 to charge the battery pack 110 according to the target charging power.

The specific calculation mode for calculating the target discharge power is not limited, and the invention concept of determining the target discharge power based on the difference between the actual grid-connected power and the target grid-connected power can be satisfied. For example, in other embodiments, the power loss in the power supply system, or the error of the smart grid monitoring module may be further combined, so as to determine the target discharge power according to the difference between the actual grid-connected power and the target grid-connected power.

Referring to fig. 7, in some embodiments, the control method further includes:

step S701: the sampled output power of the DC power generation device is periodically collected.

In some embodiments, the sampled output power of the DC power generation device 130 may be collected in real time by providing a sensor (e.g., a Hall sensor, or other power measurement sensor) at the output of the DC power generation device 130, and the controller in communication with the sensor. In other embodiments, a current sensor and a voltage sensor may be disposed at the output end of the dc power generation device 130, and the controller is in communication with the sensor, so that the controller may calculate the sampled output power of the dc power generation device 130 according to the collected actual output current and the actual output voltage.

It is understood that the sampling period in step S701 may not be synchronized with the operation period in step S201, and the sampling period in step S701 is not limited in this application.

Step S702: and filtering the sampled output power to obtain the actual power generation power.

Understandably, when the direct current power generation device 130 is subjected to environmental influences, the actual power generated by the direct current power generation device 130 is liable to be dithered. For example, when the weather of the environment in which the photovoltaic module is located in the direct current power generation apparatus 130 changes or the photovoltaic module is shielded by a shielding object (for example, a cloud layer, a leaf, etc.), the actual power generated by the photovoltaic module is easily dithered. Therefore, in step S702, the power filter value is obtained by filtering the actual generated power to eliminate jitter in the actual generated power as much as possible.

The filtering process in step S702 may be a filtering process based on a low-pass filtering, an average filtering, a median filtering algorithm, or the like, and the filtering algorithm employed in step S702 is not limited in this application.

In summary, by executing steps S701 to S702, the obtained actual generated power can be more accurate, and the interference of the environment where the dc power generating device 130 is located on the present solution is reduced.

With continued reference to fig. 8, fig. 8 shows a specific control block diagram and a power trend diagram for implementing a charging control method of a power supply circuit according to an embodiment of the present application by using a closed-loop control algorithm. The following describes a specific workflow of a charge control method of the power supply circuit according to fig. 8:

first, the actual grid-connected power p_real between the ac bus and the power grid 20 is obtained by the smart meter 40, so as to calculate the deviation power p_dev between the actual grid-connected power p_real and the target grid-connected power p_ aim by the first adder 151. The target charging power p_dsg of the power supply circuit 120 is then determined according to the deviation power p_dev and a deviation adjustment algorithm preset in the PI controller 152.

Further, the reserve power p_res of the current operation period and the actual power generation power p_pv of the direct current power generation device 130 are acquired to determine the charging power upper limit p_max by the second adder 153. The reserved power p_res of the current operation period is calculated according to the actual power generation power p_pv of the direct current power generation device, the power fluctuation coefficient and the reserved power of the previous operation period based on the algorithm provided by the embodiment of the application.

Then, the limiter 154 performs a limiter process on the target charging power p_dsg according to the charging power upper limit p_max to obtain the limiter-processed target charging power p_dsg_tag.

Further, the power supply circuit 120 takes power from the dc bus according to the target charging power p_dsg_tag after the clipping process. The remaining power of the photovoltaic power p_pv is input to the dc input of the inverter 140. That is, the dc power p_dc obtained at the dc input of the inverter 140 can be obtained by subtracting the target charging power p_dsg_tag after the clipping process from the photovoltaic power p_pv by the third adder 155. Inverter 140 power converts dc power p_dc received at the dc input to output ac power p_ac to the ac bus to provide at least a portion of the demanded power p_feed to load 30. Further, the fourth adder 156 may calculate the power that is not satisfied by the load 30, or the power that flows to the power grid 20 after the ac power p_ac satisfies the required power p_seed of the load.

It is to be understood that the PI controller 152 is exemplified by an existing controller in the related art such as PI controller (proportional integral controller, proportional-integral controller). In other embodiments, other controllers such as PID controllers (proportional integral Differentiation controller, proportional-integral-derivative controllers) and the like may be employed, as the present application is not limited in this regard. Correspondingly, the deviation adjustment algorithm may be a PI adjustment algorithm (proportional integral control, proportional integral adjustment), a PID adjustment algorithm (ProportionIntegration Differentiation control, proportional integral differential adjustment), or the like, but may be other adjustment algorithms.

In this way, the reserved power can be updated in each operation period, so that the normal operation of the inverter is ensured when the battery pack is charged.

Referring to fig. 9, the present application further provides a power supply apparatus 100, including a power supply circuit 120 and a controller 150. The power supply apparatus 100 is provided to the power supply system 10. The power supply system 10 includes a battery pack 110, a dc power generation device 130, an inverter 140, and a power supply device 100. The first end of the power supply circuit 120 is used for being connected to the battery pack 110, and the second end of the power supply circuit 120, the output end of the dc power generation device 130, and the dc input end of the inverter 140 are all connected to the dc bus. The power supply circuit 120 receives power from the battery pack 110 and outputs the power to the dc bus when discharging. The controller 150 is configured to execute the discharge control method of the power supply circuit described in any one of the embodiments.

In some embodiments, the dc bus is configured within the power supply apparatus 100. In other embodiments, the dc bus may also be configured by other electronic devices connected to the power supply device 100, such as by the inverter 140.

Referring to fig. 10, the present application further provides an energy storage device 200. The energy storage device 200 includes a power supply circuit 120, a battery pack 110, and a controller 150. The energy storage device 200 is disposed in the power supply system 10. The power supply system 10 includes a dc power generation device 130, an inverter 140, and an energy storage device 200. The first end of the power supply circuit 120 is used for being connected to the battery pack 110, and the second end of the power supply circuit 120, the output end of the dc power generation device 130, and the dc input end of the inverter 140 are all connected to the dc bus. The power supply circuit 120 receives power from the battery pack 110 and outputs the power to the dc bus when discharging. The controller 150 is configured to execute the discharge control method of the power supply circuit according to any one of the embodiments described above.

It is appreciated that in some embodiments, a dc bus may also be provided in the energy storage device 200. In other embodiments, the dc bus may also be configured by other electronics coupled to the energy storage device 200, such as by the inverter 140.

It is understood that the energy storage device 200 may be various electronic devices provided with the battery pack 110, such as, for example, a mobile energy storage device, a home energy storage device, a mobile air conditioner, a mobile refrigerator, etc., and the present application is not limited to the specific functions of the energy storage device 200.

As can be appreciated, the controller 150 is loaded with the energy management system EMS (Energy Management System), and the EMS is configured to perform the discharge control method of the power supply circuit provided herein, so as to implement uniform control over the energy storage device 200. The controller 150 may be a processor independent of the battery pack 110 and the power supply circuit 120, or the controller 150 may be a processor for controlling the battery pack 110, which is loaded with the battery management system BMS (Battery Management System) at the same time. The present application is not limited to the specific form of the controller.

In some embodiments, the controller 150 may communicate with the battery pack 110 via a CAN bus, and the controller 150 may communicate with the power circuit 120 and the electricity meter via an RS-485 serial bus. In other embodiments, the controller 150 may also communicate with the battery pack 110 and the power supply circuit 120 by other wired or wireless communication methods, which is not limited in this application.

An embodiment of the present application further provides a control device applied to the power supply circuit 120 or the electronic device integrated with the power supply circuit 120. Fig. 11 schematically shows a block diagram of a control device 300 according to an embodiment of the present application. As shown in fig. 11, the control device 300 includes:

an obtaining module 310, configured to obtain, in each operation period, a reserved power of the inverter in a previous operation period, an actual power generation power of the dc power generation device, and a power fluctuation coefficient; the power fluctuation coefficient is used for representing the fluctuation degree of the actual generated power.

The first determining module 320 is configured to determine the reserved power of the current operation period according to the reserved power of the previous operation period and the power fluctuation coefficient.

The second determining module 330 is configured to determine an upper limit of the charging power according to the actual generated power and the reserved power of the current operation period.

And the clipping module 330 is configured to perform clipping processing on the target charging power of the power supply circuit according to the charging power upper limit.

And the control module 340 is configured to obtain electric energy from the dc bus to charge the battery pack according to the target charging power after the clipping processing.

Specific details of the control device 300 for implementing the discharge control method of the power supply circuit provided in the embodiment of the present application have been described in detail in the embodiment of the discharge control method of the corresponding power supply circuit, and are not described herein again.

The present application also provides a computer-readable medium on which a computer program is stored which, when executed by a processor, implements a discharge control method of a power supply circuit as in the above technical solutions. The computer readable medium may take the form of a portable compact disc read only memory (CD-ROM) and include program code that can be run on a terminal device, such as a personal computer. However, the program product of the present invention is not limited thereto, and in this document, a readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

The program product described above may take the form of any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium would include the following: an electrical connection having one or more wires, a portable disk, a hard disk, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

The computer readable signal medium may include a data signal propagated in baseband or as part of a carrier wave with readable program code embodied therein. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A readable signal medium may also be any readable medium that is not a readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

Program code embodied on a readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Program code for carrying out operations of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device, partly on a remote computing device, or entirely on the remote computing device or server. In the case of remote computing devices, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., connected via the Internet using an Internet service provider).

Furthermore, the above-described drawings are only schematic illustrations of processes included in the method according to the exemplary embodiment of the present invention, and are not intended to be limiting. It will be readily appreciated that the processes shown in the above figures do not indicate or limit the temporal order of these processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, for example, among a plurality of modules.

The foregoing is merely a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any equivalent modifications or substitutions will be apparent to those skilled in the art within the scope of the present application, and these modifications or substitutions should be covered in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The charging control method of the power supply circuit is characterized in that the power supply system comprises a battery pack, direct current power generation equipment, an inverter and the power supply circuit, wherein a first end of the power supply circuit is used for being connected with the battery pack, and a second end of the power supply circuit, an output end of the direct current power generation equipment and a direct current input end of the inverter are all connected to a direct current bus; the method comprises the following steps:

In each operation period, acquiring reserved power of the inverter in the last operation period, actual power generation power of the direct current power generation equipment and a power fluctuation coefficient; the power fluctuation coefficient is used for representing the fluctuation degree of the actual generated power;

determining the reserved power of the current operation period according to the reserved power of the previous operation period and the power fluctuation coefficient;

determining an upper limit of charging power according to the actual power generation power and the reserved power of the current running period;

performing amplitude limiting processing on the target charging power of the power supply circuit according to the upper limit of the charging power;

and acquiring electric energy from the direct current bus according to the target charging power after the amplitude limiting treatment to charge the battery pack.

2. The method according to claim 1, wherein the method further comprises:

acquiring a plurality of actual power generation powers of the direct current power generation equipment acquired within a preset time period;

calculating average values and average variances of the actual power generation power acquired in the preset time period;

and determining the power fluctuation coefficient according to the average variance and the average value.

3. The method of claim 2, wherein said determining said power fluctuation coefficient from said average variance and said average value comprises:

A ratio of the average variance to the square of the average is calculated as the power fluctuation coefficient.

4. The method of claim 1, wherein determining the reserved power for the current operating cycle based on the reserved power for the previous operating cycle and the power fluctuation coefficient comprises:

determining an adjustment coefficient according to the power fluctuation coefficient and a power fluctuation coefficient reference value, wherein the power fluctuation coefficient and the adjustment coefficient are in positive correlation;

determining a power adjustment step length according to the adjustment coefficient and a reference step length, wherein the power adjustment step length and the power adjustment coefficient are in positive correlation;

and determining the reserved power of the current operation period according to the reserved power of the last operation period and the power adjustment step length.

5. The method according to claim 1, wherein the determining the upper limit of the charging power from the actual generated power and the reserved power of the current operation period includes

And calculating the difference between the actual power generation power and the reserved power of the current operation period as the upper limit of the charging power.

6. The method of claim 1, wherein clipping the target charging power of the power supply circuit according to the charging power upper limit comprises:

Acquiring target charging power of the power supply circuit;

when the target charging power is greater than the upper charging power limit, adjusting the target charging power to the upper charging power limit;

and when the target charging power is not greater than the upper limit of the charging power, not adjusting the target charging power.

7. The method of claim 1, wherein the ac output of the inverter is connected to a power grid via an ac bus, the method further comprising:

acquiring actual grid-connected power between the alternating current bus and the power grid;

and determining the target charging power of the power supply circuit according to the actual grid-connected power and the target grid-connected power.

8. The method according to claim 1, wherein the method further comprises:

periodically collecting the sampling output power of the direct current power generation equipment;

and filtering the sampled output power to obtain the actual power generation power.

9. A power supply device, characterized in that the power supply device comprises a power supply circuit and a controller, the power supply device is arranged in a power supply system, the power supply system comprises a battery pack, a direct current power generation device, an inverter and the power supply circuit, a first end of the power supply circuit is used for being connected with the battery pack, a second end of the power supply circuit, an output end of the direct current power generation device and a direct current input end of the inverter are all connected to a direct current bus, and the controller is used for executing the charging control method of the power supply circuit according to any one of claims 1-8.

10. The energy storage device is characterized by comprising a power supply circuit, a battery pack and a controller, wherein the energy storage device is arranged in a power supply system, the power supply system comprises the energy storage device, direct current power generation equipment and an inverter, a first end of the power supply circuit is used for being connected with the battery pack, and a second end of the power supply circuit, an output end of the direct current power generation equipment and a direct current input end of the inverter are all connected to a direct current bus; the controller is configured to execute the charge control method of the power supply circuit according to any one of claims 1 to 8.