Photovoltaic storage system control method, control circuit, photovoltaic storage system and electronic equipment

Abstract

The present application relates to a photovoltaic storage system control method, a control circuit, a photovoltaic storage system and an electronic device, the method comprising the steps of: obtaining the state parameters of the maximum power point tracking MPPT controller and the battery; and adjusting the operating state of the battery according to the state parameters. The current operating state of the battery can be known through the state parameters of the battery, and the operating parameters of the battery can be adjusted according to the different operating states of the battery, so that the battery can be kept in a stable state for different system conditions, thereby realizing the application of small-capacity batteries in the photovoltaic storage system and reducing the battery cost of the photovoltaic storage system.

Description

Technical Field

[0001] The present application relates to the photovoltaic field, and in particular to a photovoltaic storage system control method, a control circuit, a photovoltaic storage system and an electronic device. Background Art

[0002] In traditional photovoltaic storage systems, the front-stage photovoltaic MPPT controller and the rear-stage energy storage inverter DC / AC discharge are decoupled. When a sudden change occurs in the system, it is easy to cause damage to the battery and affect the battery life. Therefore, the battery of the existing photovoltaic storage system needs to use a larger capacity battery to reduce the impact of the sudden change, and the battery cost is relatively high. Summary of the invention

[0003] The present application provides a photovoltaic storage system control method, a control circuit, a photovoltaic storage system and an electronic device, aiming to solve the technical problem of high battery cost in the prior art.

[0004] In order to solve the above technical problem or at least partially solve the above technical problem, the present application provides a method for controlling a photovoltaic storage system, the method comprising the steps of:

[0005] Obtaining battery status parameters;

[0006] The operating state of the battery is adjusted according to the state parameter.

[0007] Optionally, the step of adjusting the operating state of the battery according to the battery voltage includes:

[0008] Obtaining a battery voltage of the battery and a preset voltage hysteresis interval, and determining whether the battery voltage is greater than a maximum value of the voltage hysteresis interval or less than a minimum value of the voltage hysteresis interval;

[0009] If the battery voltage is greater than the maximum value of the voltage hysteresis interval, the battery is controlled to discharge with adjusted power; if the battery voltage is less than the minimum value of the voltage hysteresis interval, the battery is controlled to charge with the battery target power; if the battery voltage is within the voltage hysteresis interval, the current state of the battery is kept unchanged.

[0010] Optionally, the step of controlling the battery to discharge with adjusted power includes:

[0011] The battery discharge power of the battery is set to 0, and the target output power is updated to the sum of the regulated power and the MPPT power.

[0012] Optionally, the state parameter includes a battery voltage of the battery, and the step before controlling the battery to be charged at a battery target power further includes:

[0013] Obtaining a preset adjustment coefficient, a floating charge voltage of the battery, and the battery voltage;

[0014] The battery target power is calculated according to the preset adjustment coefficient, the float charge voltage and the battery voltage.

[0015] Optionally, the state parameter includes a battery voltage of a battery; and the step of adjusting the operating state of the battery according to the state parameter includes:

[0016] When the photovoltaic storage system is connected to the grid, a preset over-discharge voltage is obtained, and it is determined whether the battery voltage is less than the preset over-discharge voltage;

[0017] If the battery voltage is lower than the preset over-discharge voltage, charging the battery through the power grid;

[0018] Obtaining a preset recovery voltage, and continuously determining whether the battery voltage is greater than the preset recovery voltage;

[0019] If the battery voltage is greater than the preset recovery voltage, charging the battery through the power grid is stopped.

[0020] Optionally, the method further comprises:

[0021] When the photovoltaic storage system is connected to the grid, obtaining the battery target power of the battery and the MPPT power of the MPPT controller;

[0022] The target output power of the energy storage converter is obtained according to the battery target power and the MPPT power.

[0023] Optionally, the method further comprises:

[0024] When the photovoltaic storage system is off-grid, obtaining the battery voltage of the battery and the actual inverter power of the energy storage converter;

[0025] The target MPPT power of the MPPT controller is obtained according to the battery voltage and the actual inverter power.

[0026] To achieve the above object, the present invention further provides a photovoltaic storage system control circuit, which is applied to the photovoltaic storage system control method as described above, and the photovoltaic storage system control circuit includes: an MPPT controller, a storage battery and an energy storage inverter; the input end of the MPPT controller is connected to the solar module, the output end of the MPPT controller is respectively connected to the storage battery and the energy storage inverter, the storage battery is also connected to the energy storage inverter, the AC output end of the energy storage inverter serves as the output end of the photovoltaic storage system control circuit, the energy storage inverter includes a central controller, and the central controller is respectively connected to the MPPT controller and the storage battery; wherein:

[0027] The central controller is used to obtain the state parameters of the battery and adjust the operating state of the battery according to the state parameters.

[0028] To achieve the above objectives, the present invention further provides a photovoltaic storage system, which includes a solar energy component and the photovoltaic storage system control circuit as described above, wherein the solar energy component is connected to the photovoltaic storage system control circuit.

[0029] To achieve the above object, the present invention further provides an electronic device, which is applied to the above-mentioned photovoltaic storage system control method, and the electronic device includes:

[0030] A first acquisition module, used to acquire the state parameters of the battery;

[0031] The first adjustment module is used to adjust the operating state of the battery according to the state parameter.

[0032] Optionally, the first adjustment module includes:

[0033] a first judgment unit, configured to obtain a battery voltage of the battery and a preset voltage hysteresis interval, and judge whether the battery voltage is greater than a maximum value of the voltage hysteresis interval or less than a minimum value of the voltage hysteresis interval;

[0034] The first control unit is used to control the battery to discharge with adjusted power if the battery voltage is greater than the maximum value of the voltage hysteresis interval; control the battery to charge with a battery target power if the battery voltage is less than the minimum value of the voltage hysteresis interval; and keep the current state of the battery unchanged if the battery voltage is within the voltage hysteresis interval.

[0035] Optionally, the first control unit includes:

[0036] The first updating subunit is used to set the battery discharge power of the battery to 0, and update the target output power to the sum of the adjustment power and the MPPT power.

[0037] Optionally, the state parameter includes a battery voltage of the battery, and the first adjustment module further includes:

[0038] A first acquisition unit, used to acquire a preset adjustment coefficient, a floating charge voltage of the battery, and the battery voltage;

[0039] The first calculation unit is used to calculate the battery target power according to the preset adjustment coefficient, the float charge voltage and the battery voltage.

[0040] Optionally, the state parameter includes a battery voltage of a battery; and the first adjustment module includes:

[0041] A second judgment unit is used to obtain a preset over-discharge voltage when the photovoltaic storage system control circuit is connected to the grid, and to judge whether the battery voltage is less than the preset over-discharge voltage;

[0042] A first execution unit, configured to charge the storage battery through a power grid if the battery voltage is less than the preset over-discharge voltage;

[0043] A second acquisition unit, used to acquire a preset recovery voltage and continuously determine whether the battery voltage is greater than the preset recovery voltage;

[0044] The second execution unit is used to stop charging the storage battery through the power grid if the battery voltage is greater than the preset recovery voltage.

[0045] Optionally, the electronic device further includes:

[0046] The second acquisition module is used to acquire the battery target power of the battery and the MPPT power of the MPPT controller when the photovoltaic storage system is connected to the grid;

[0047] The first execution module is used to obtain the target output power of the energy storage inverter according to the battery target power and the MPPT power.

[0048] Optionally, the electronic device further includes:

[0049] A third acquisition module is used to obtain the battery voltage of the battery and the actual inverter power of the energy storage converter when the photovoltaic storage system is off-grid;

[0050] The second execution unit is used to obtain the target MPPT power of the MPPT controller according to the battery voltage and the actual inverter power.

[0051] The present invention proposes a control method for a photovoltaic storage system, a control circuit, a photovoltaic storage system and an electronic device, which obtains the state parameters of the storage battery; and adjusts the operating state of the storage battery according to the state parameters. The current operating state of the storage battery can be known through the state parameters of the storage battery, and the operating parameters of the storage battery can be adjusted according to the different operating states of the storage battery, so that the storage battery can be kept in a stable state for different system conditions, thereby realizing the application of small-capacity batteries in the photovoltaic storage system and reducing the battery cost of the photovoltaic storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0054] Figure 1 It is a structural schematic diagram of the optical storage system of the present invention;

[0055] Figure 2 It is a flow chart of the first embodiment of the control method of the photovoltaic storage system of the present invention;

[0056] Figure 3 It is a schematic diagram of the electrical signal transmission of the control circuit of the optical storage system of the present invention;

[0057] Figure 4 A schematic diagram of key voltage points of a battery in the photovoltaic storage system of the present invention;

[0058] Figure 5 The charging characteristic curve diagram of the storage battery in the photovoltaic storage system of the present invention;

[0059] Figure 6 The figure is a discharge characteristic curve diagram of the battery in the photovoltaic storage system of the present invention.

[0060] Description of Figure Numbers:

[0061] Label name Label name 100 MPPT Controller 200 Energy Storage Converter 300 Battery 201 Central Controller DETAILED DESCRIPTION

[0062] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only embodiments of a part of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work should fall within the scope of protection of the present application.

[0063] The present invention provides a method for controlling a photovoltaic storage system. The method is applied to a control circuit of a photovoltaic storage system. Figure 1 , the photovoltaic storage system control circuit includes: an MPPT (Maximum Power Point Tracking) controller 100, a battery 300 and an energy storage inverter 200; the input end of the MPPT controller 100 is connected to the solar panel, the output end of the MPPT controller 100 is respectively connected to the battery 300 and the energy storage inverter 200, the battery 300 is also connected to the energy storage inverter 200, the AC output end of the energy storage inverter 200 serves as the output end of the photovoltaic storage system control circuit, the energy storage inverter 200 includes a central controller 201, and the central controller 201 is respectively connected to the MPPT controller 100 and the battery 300; wherein:

[0064] The central controller 201 is used to obtain the state parameters of the MPPT controller 100 and the battery 300 , and adjust the operating parameters of the battery 300 according to the state parameters to adjust the operating state of the battery 300 .

[0065] The solar module is used to convert light energy into electrical energy and output it to the MPPT controller 100; the central controller 201 sends a tracking instruction to the MPPT controller 100 according to the energy demand, and the MPPT controller 100 performs MPPT tracking according to the tracking instruction; the MPPT controller 100 transmits energy to the DC bus, that is, to the battery 300 and / or the energy storage converter 200; the output end of the energy storage converter 200 is connected to the grid and the load respectively, and the energy storage converter 200 can automatically switch between the grid-connected and off-grid modes, and the grid-connected mode refers to the connection with the grid, and the off-grid mode refers to the disconnection from the grid; in the grid-connected mode, the output power of the energy storage converter 200 is controlled by the instructions sent by the central controller 201, and in the off-grid mode, the output power of the energy storage converter 200 is determined by the characteristics of the load. The central controller 201 uniformly dispatches the power of the front and rear stages of the photovoltaic storage system, that is, the tracking power of the MPPT and the output power of the energy storage converter 200, and the central controller 201 has the functions of battery parameter reading, power demand calculation, millisecond power scheduling and system protection.

[0066] The basic control logic in different modes of this embodiment is:

[0067] In the grid-connected mode, the front-stage MPPT controller 100 slowly tracks the MPPT power, and the photovoltaic energy output by the solar panel is used as the main input energy and plays a leading role. The system gives priority to using photovoltaic energy to ensure the charging energy of the battery for subsequent use. The rear-stage energy storage converter 200 operates in the grid-connected discharge mode. The grid is the energy output end. When the photovoltaic energy is sufficient, that is, when the load power supply and the charging energy of the battery 300 can be guaranteed, the excess energy is fed into the grid through the energy storage converter 200. In the off-grid mode, the rear-stage energy storage converter 200 operates in the off-grid discharge mode, with photovoltaic energy as the main input energy and the load as the energy output object, and the load energy demand plays a leading role; the central controller 201 sends instructions to the MPPT controller 100 to track the MPPT, and at the same time, the central controller 201 sends instructions to the battery 300 to control the charging and discharging power of the battery 300; when the photovoltaic energy is sufficient, the load is mainly powered by photovoltaic energy, and the excess energy is used to charge the battery 300; when the photovoltaic energy is insufficient, the battery 300 is used for auxiliary power supply to ensure the effective power supply of the load.

[0068] Reference Figure 2 , Figure 2 This is a flow chart of a first embodiment of a control method for a photovoltaic storage system according to the present invention. The method comprises the following steps:

[0069] Step S10, obtaining the state parameters of the battery;

[0070] The status parameters include the battery voltage of the battery; the current battery status of the battery can be understood based on the status parameters.

[0071] Step S20: adjusting the operating state of the battery according to the state parameter.

[0072] The operating state of the battery is adjusted based on the state parameters of the battery itself, thereby avoiding the impact of circuit fluctuations or mutations on the battery and keeping the battery in the optimal operating state at all times.

[0073] This embodiment can know the current operating state of the battery through the state parameters of the battery, and adjust the operating parameters of the battery according to the different operating states of the battery, so that the battery can be kept in a stable state for different system conditions, thereby realizing the application of small-capacity batteries in the photovoltaic storage system and reducing the battery cost of the photovoltaic storage system.

[0074] Further, in the second embodiment of the control method of the photovoltaic storage system of the present invention proposed based on the first embodiment of the present invention, the state parameter includes the battery voltage of the battery, and the step S20 includes the steps of:

[0075] The step S20 comprises the steps of:

[0076] Step S21, obtaining the battery voltage of the battery and a preset voltage hysteresis interval, and determining whether the battery voltage is greater than a maximum value of the voltage hysteresis interval or less than a minimum value of the voltage hysteresis interval;

[0077] Step S22, if the battery voltage is greater than the maximum value of the voltage hysteresis interval, the battery is controlled to discharge with adjusted power; if the battery voltage is less than the minimum value of the voltage hysteresis interval, the battery is controlled to charge with the battery target power; if the battery voltage is within the voltage hysteresis interval, the current state of the battery is kept unchanged.

[0078] When the photovoltaic storage system is connected to the grid, obtaining the battery target power of the battery and the MPPT power of the MPPT controller;

[0079] The target output power of the energy storage converter is obtained according to the battery target power and the MPPT power.

[0080] Specifically, in the grid-connected mode, the battery target power is determined based on the battery's own operating status, and the MPPT power is determined based on the photovoltaic energy; when the photovoltaic energy is sufficient, the system works in a steady state, and as the battery is gradually filled, the battery power decreases, and the target output power gradually increases. The front-stage MPPT controller always works at the MPPT point, making full use of the photovoltaic energy, and the central controller controls the target output power of the energy storage inverter to follow the MPPT power in real time; when the photovoltaic energy is insufficient, the target output power decreases as the MPPT power decreases; in this process, since the front-stage MPPT controller will have power fluctuations and there is a response delay in the control, the target output power of the energy storage inverter cannot completely follow the MPP synchronously Changes of T controller; for example, in steady state, the MPPT power drops slightly. Due to the control delay, the battery discharges during the delay period. After the delay, the target output power synchronizes with the change of MPPT power. At this time, the battery resumes charging. Therefore, when the MPPT power fluctuates, it will cause frequent small current charging and discharging problems in the battery. Here, a voltage hysteresis interval is established. The battery saturation area is above the voltage hysteresis interval. When the battery voltage is in the battery saturation area, the battery is in a discharging state by adjusting the power; and the under-saturation area is below the voltage hysteresis interval. When the battery voltage is in the under-saturation area, the battery is controlled to be in a charging state to reduce the charging and discharging frequency and ensure the battery life.

[0081] When the photovoltaic storage system is off-grid, obtaining the battery voltage of the battery and the actual inverter power of the energy storage converter;

[0082] The target MPPT power of the MPPT controller is obtained according to the battery voltage and the actual inverter power.

[0083] Specifically, in off-grid mode, a microgrid system is established on the inverter side of the rear-stage energy storage converter, which serves as an AC source to stably and continuously supply power to the load. The actual inverter power is determined based on the actual power of the load, and the central controller dynamically adjusts the MPPT power according to the load power and battery voltage. When the photovoltaic energy is sufficient, the MPPT power can guarantee the power demand of the AC load, and at the same time, the MPPT power is used to replenish the energy of the battery. The fluctuation of photovoltaic power will cause the battery charging current to fluctuate. It is necessary to dynamically adjust the battery charging current according to the battery charging and discharging characteristic curve, so as to adjust the MPPT power in time; when the photovoltaic energy is insufficient, the photovoltaic energy and the battery energy complement each other to ensure the stable power supply of the AC side load. At this time, the MPPT power will also fluctuate near the load power, which will cause the battery to frequently enter charging and discharging; the voltage hysteresis interval is also established, and the battery is in a discharge state by adjusting the power above the voltage hysteresis interval, and is charged according to the predetermined battery charging power below the voltage hysteresis area. This can effectively prevent the battery from being frequently charged and discharged, and can also prevent the overvoltage fault caused by the voltage recovery during the unloading process. It should be noted that the photovoltaic energy shortage mentioned above refers to the situation where the MPPT power fluctuates near the load power. When the photovoltaic energy is seriously insufficient, that is, it is completely impossible to power the AC load only by photovoltaic energy, the voltage hysteresis interval is cancelled, and the AC load is powered by battery energy. Specifically, the serious shortage of photovoltaic energy can be judged in different ways. It can be set that when the MPPT power is less than the preset low photovoltaic power for a preset time, the photovoltaic energy is considered to be seriously insufficient. It can also be judged by time. Since the light is weak at night, the night time, such as 18:00-8:00, can be set as the preset low photovoltaic time interval. When the system time is When the low photovoltaic time interval is preset, it is considered that the photovoltaic energy is seriously insufficient. It can be understood that the preset low photovoltaic time interval can be set accordingly according to different factors such as date and location, which are not limited here; it can also be judged by weather conditions, such as obtaining the current weather conditions. If the weather is cloudy, overcast, rainy, snowy, foggy, etc., it is considered that the photovoltaic energy is seriously insufficient. The photovoltaic energy situation corresponding to the specific weather conditions can be set according to the actual application scenario, which is not limited here; it should be noted that the above different schemes can be selected separately or combined to judge the photovoltaic energy situation, and different schemes can be set correspondingly in different application scenarios and actual needs. It should be noted that since photovoltaic energy mainly depends on light, this embodiment can also be combined with other methods of judging light intensity in the prior art to judge the photovoltaic energy situation. On the basis of this embodiment, other methods of judging light intensity should also be within the scope of protection of this application.

[0084] The following is an explanation based on the working principle of the photovoltaic storage system.

[0085] The calculation formula of MPPT power is as follows:

[0086] P MPPT =P inv -P Battery -P Δ

[0087] Where: P MPPT is the target MPPT power of MPPT, P inv is the actual inverter power

[0088] See also Figure 3 , Figure 3 The figure is a schematic diagram of the electrical signal transmission of the control circuit of the photovoltaic storage system of the present invention. The calculation formula of the actual inverter power is as follows:

[0089] P inv =I inv_dc ×V bus

[0090] Among them, I inv_dc is the charging current, V bus is the bus voltage.

[0091] The step S22 comprises the steps of:

[0092] Step S221, setting the battery discharge power of the battery to 0, and updating the target output power to the sum of the adjustment power and the MPPT power.

[0093] The adjustment formula of target output power is as follows:

[0094] P inv_set =P MPPT_fb +P Battery +P Δ

[0095] Among them, P inv_set is the target output power, P MPPT_fb is the actual power of MPPT, P Battery is the battery target power (negative when charging), P Δ To adjust the power.

[0096] During the operation of the photovoltaic storage system, the allowable charging current of the battery needs to be dynamically adjusted. It is necessary to study the charging current requirements of lead-acid batteries in different voltage ranges. Figure 4 The key voltage points of the battery include the single cell voltage Vcell, single cell floating charge voltage Vbat_float, single cell protection voltage Vbat_protect and discharge end voltage EOD. This patent takes KSTARGFM600T lead-acid battery as an example. Figure 5It is the charging characteristic curve of lead-acid battery at 25℃, battery voltage, charging current and battery capacity.

[0097] In grid-connected mode, when the light intensity is unstable, the fluctuation of photovoltaic power, that is, the fluctuation of MPPT power, will cause frequent charging and discharging of the battery, which will affect the life of the battery; in off-grid mode, when the load is constant, the inverter power is constant, and the battery target power is constant, so the required output MPPT power is constant. If the photovoltaic power is unstable, the actual output MPPT power cannot reach the target output power, which will cause the battery to frequently switch between charging and discharging, affecting the battery life. This embodiment divides the voltage into three zones according to the capacity, namely the saturation zone, the critical saturation zone, and the undersaturation zone. The critical saturation zone is the voltage hysteresis zone. In steady state, when the battery voltage is in the saturation zone, the battery target power P Battery To prevent the battery from being repeatedly charged and discharged, P Battery The fixed setting is 0, and the power P Δ Let the battery be in a low-power discharge state. At this time, the fluctuation of photovoltaic power will not change the charge and discharge state of the battery. Over time, when adjusting the power P Δ Under the influence of the battery voltage from the saturation region through the critical saturation region into the undersaturation region, when the battery voltage is in the undersaturation region, the power P is adjusted. Δ Set to 0, the system returns to the battery target power P Battery Charging is carried out, and the battery slowly passes through the critical saturation zone and enters the saturation zone again. The scheme of adjusting the power plus voltage hysteresis interval is adopted to make the charging and discharging frequency of the system controllable in a steady state, effectively preventing the frequent switching of the battery charging and discharging state.

[0098] The size of the voltage hysteresis interval can be set according to the actual parameters of the battery. Taking the GFM600T lead-acid battery as an example, when the capacity is 85% or above, the charging current is allowed to decrease rapidly. At this time, the corresponding voltage is V1. When the voltage is greater than V1, it can be judged that the battery has entered the saturation zone. When the capacity is 60% or below, the backup energy is insufficient. At this time, the corresponding voltage is V2, and the voltage hysteresis interval is (V1, V2); it can be understood that a too small voltage hysteresis interval will affect the regulation effect, and a too large voltage hysteresis interval will affect the off-grid backup time. Therefore, the setting of the voltage hysteresis interval should be widened on the premise of ensuring energy backup, and the specific value of the voltage hysteresis interval should be set according to the backup demand and the battery curves of different manufacturers. In this embodiment, V1 is set to 2.27V and V2 is set to 2.1V according to the 60% backup capacity and the battery charging characteristic curve to meet the demand; the floating charge voltage is 2.3V. Similarly, the size of the regulated power can also be set according to the system requirements of the actual application. If the regulated power is too small, it will not be recognized due to the control accuracy, and if the regulated power is too large, it will shorten the time for the voltage to go out of the hysteresis zone, affecting the regulation effect. This patent takes a 50kW MPPT controller and a 50kW energy storage inverter as an example, and sets the regulated power to 1kW.

[0099] Further, the state parameter includes the battery voltage of the battery, and before step S22, the following steps are included:

[0100] Step S23, obtaining a preset adjustment coefficient, a floating charge voltage of the battery, and the battery voltage;

[0101] Step S24, calculating the battery target power according to the preset adjustment coefficient, the float charge voltage and the battery voltage.

[0102] The calculation formula for the battery target power is as follows:

[0103] P Battery = k × V cell ×(V cell -V Bat_Float )

[0104] Wherein, k is the preset adjustment coefficient.

[0105] When the photovoltaic power is sufficient and stable, the actual output MPPT power is equal to the target output power, and the system is in a power supply balance state. When the system switches from grid-connected to off-grid or loads or unloads at the load end, the power balance state is instantly broken, causing the charging current to increase. Figure 6 When the discharge current changes from 0.1C to 1C, the battery voltage does not change suddenly, but the usage time changes greatly. Figure 5 In the saturation region, the voltage rises rapidly, causing battery overcharging and even system overvoltage protection.

[0106] In this embodiment, the battery target power is designed according to the above formula. It can be seen from the expression that without the influence of the adjustment coefficient, in the under-saturation to saturation range, the battery target power decreases approximately linearly with the increase of the battery voltage. When the battery voltage suddenly changes, the battery target power quickly follows the change, and can quickly resist the impact of sudden unloading on the battery. According to the battery charging characteristic curve, the closer the battery voltage is to the saturation zone, the greater the voltage increase caused by the charging power caused by sudden unloading. At this time, the adjustment amplitude must be larger to avoid overvoltage as much as possible. Therefore, in this embodiment, the preset adjustment coefficients corresponding to different saturation zones are set separately. Specifically, the preset adjustment coefficient is set to k1 in the saturation zone, the preset adjustment coefficient is set to k2 in the critical saturation zone, and the preset adjustment coefficient is set to k3 in the under-saturation zone. The battery target power is fine-tuned and amplified in different areas, thereby further reducing the probability of overvoltage. In the undersaturated area, the possibility of overvoltage caused by sudden unloading is small. The battery target power can be obtained by multiplying the 0.25C rate charging current commonly used in engineering by the average battery voltage in the undersaturated area. The value of k3 can be calculated according to the above formula. The values ​​of k2 and k1 are fine-tuned and amplified based on k3. Too large values ​​will cause power jumps during regional transitions in the stable charging process. In this embodiment, k2 is set to 1.1k3 and k1 is set to 1.2k3. On the basis of ensuring the smooth transition of power in the stable charging process, the overvoltage protection capability caused by sudden unloading is further enhanced.

[0107] This embodiment avoids the problem of frequent switching of charging and discharging of the battery by setting a voltage hysteresis interval, and adjusts the battery target power by presetting an adjustment coefficient, so that the battery target power of the battery can be adjusted in time when the system fluctuates to avoid the occurrence of overvoltage problems.

[0108] Further, in a third embodiment of the control method of the photovoltaic storage system of the present invention proposed based on the first embodiment of the present invention, the step S20 includes the following steps:

[0109] Step S25, when the photovoltaic energy storage system is connected to the grid, obtaining a preset over-discharge voltage, and determining whether the battery voltage is less than the preset over-discharge voltage;

[0110] Step S26, if the battery voltage is less than the preset over-discharge voltage, charging the battery through the power grid;

[0111] Step S27, obtaining a preset recovery voltage, and continuously determining whether the battery voltage is greater than the preset recovery voltage;

[0112] Step S28: If the battery voltage is greater than the preset recovery voltage, then stop charging the battery through the power grid.

[0113] When the photovoltaic storage system is in grid-connected mode at night, due to the lack of light, the front-end MPPT controller and the back-end energy storage inverter will stop working, but the photovoltaic storage system will remain in standby mode. At this time, the battery has a small current discharge that lasts for a long time. When it is in rainy weather for a long time or when powering a small load for a long time, the battery energy cannot be replenished in time, resulting in deep discharge of the battery. When the battery is in a deep power loss state for a long time, it will greatly affect the battery life.

[0114] This embodiment sets a preset over-discharge voltage and a preset recovery voltage. The preset over-discharge voltage is V L -Δ, the preset recovery voltage is V L +Δ, where V L is the battery discharge termination voltage, Δ protection parameter, specifically V L The value of Δ can be set according to the battery parameters and the actual required standby time or backup time. In this embodiment, V L is 1.8V, Δ is 0.5V; when the battery voltage is lower than the preset over-discharge voltage, it means that the battery is in a deep power-deficient state, and the grid forced charging mechanism is activated to charge the battery at a low power; when the battery voltage reaches the preset recovery voltage, it is considered that the battery has recovered to a normal state, and the grid forced charging mechanism is exited at this time, and the battery charging is stopped, and the battery is charged again when the photovoltaic energy is sufficient. It should be noted that the user can also customize the charging curve segment, and when the battery voltage is in the charging curve segment, the grid forced charging mechanism is activated.

[0115] This embodiment can prevent the battery from being deeply discharged for a long time, which affects the service life of the battery.

[0116] Furthermore, the capacity of the battery will decrease as the battery is used for a longer time. In this embodiment, the capacity of the battery can be fully charged and discharged through the power grid in a timed manner during the idle time of the battery, such as at night, so that the capacity loss of the battery after long-term operation can be optimized. The activation cycle can be set according to actual needs, such as performing capacity activation once a week or a month.

[0117] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0118] Through the description of the above implementation methods, those skilled in the art can clearly understand that the method according to the above embodiment can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0119] The present application also provides an electronic device for implementing the above-mentioned photovoltaic storage system control method. The electronic device is applied to the above-mentioned photovoltaic storage system control method. The electronic device includes:

[0120] A first acquisition module, used to acquire the state parameters of the battery;

[0121] The first adjustment module is used to adjust the operating state of the battery according to the state parameter.

[0122] The control circuit of the photovoltaic storage system can know the current operating state of the battery through the state parameters of the battery, and adjust the operating parameters of the battery according to the different operating states of the battery, so that the battery can be kept in a stable state for different system conditions, thereby realizing the application of small-capacity batteries in the photovoltaic storage system and reducing the battery cost of the photovoltaic storage system.

[0123] It should be noted that the first acquisition module in this embodiment can be used to execute step S10 in the embodiment of the present application, and the first adjustment module in this embodiment can be used to execute step S20 in the embodiment of the present application.

[0124] Furthermore, the first adjustment module includes:

[0125] a first judgment unit, configured to obtain a battery voltage of the battery and a preset voltage hysteresis interval, and judge whether the battery voltage is greater than a maximum value of the voltage hysteresis interval or less than a minimum value of the voltage hysteresis interval;

[0126] The first control unit is used to control the battery to discharge with adjusted power if the battery voltage is greater than the maximum value of the voltage hysteresis interval; control the battery to charge with a battery target power if the battery voltage is less than the minimum value of the voltage hysteresis interval; and keep the current state of the battery unchanged if the battery voltage is within the voltage hysteresis interval.

[0127] Furthermore, the first control unit includes:

[0128] The first updating subunit is used to set the battery discharge power of the battery to 0, and update the target output power to the sum of the adjustment power and the MPPT power.

[0129] Further, the state parameter includes the battery voltage of the battery, and the first adjustment module further includes:

[0130] A first acquisition unit, used to acquire a preset adjustment coefficient, a floating charge voltage of the battery, and the battery voltage;

[0131] The first calculation unit is used to calculate the battery target power according to the preset adjustment coefficient, the float charge voltage and the battery voltage.

[0132] Further, the state parameter includes a battery voltage of a battery; and the first adjustment module includes:

[0133] A second judgment unit is used to obtain a preset over-discharge voltage when the photovoltaic storage system control circuit is connected to the grid, and to judge whether the battery voltage is less than the preset over-discharge voltage;

[0134] A first execution unit, configured to charge the storage battery through a power grid if the battery voltage is less than the preset over-discharge voltage;

[0135] A second acquisition unit, used to acquire a preset recovery voltage and continuously determine whether the battery voltage is greater than the preset recovery voltage;

[0136] The second execution unit stops charging the storage battery through the power grid if the battery voltage is greater than the preset recovery voltage.

[0137] Furthermore, the electronic device further comprises:

[0138] The second acquisition module is used to acquire the battery target power of the battery and the MPPT power of the MPPT controller when the photovoltaic storage system is connected to the grid;

[0139] The first execution module is used to obtain the target output power of the energy storage inverter according to the battery target power and the MPPT power.

[0140] Furthermore, the electronic device further comprises:

[0141] A third acquisition module is used to obtain the battery voltage of the battery and the actual inverter power of the energy storage converter when the photovoltaic storage system is off-grid;

[0142] The second execution unit is used to obtain the target MPPT power of the MPPT controller according to the battery voltage and the actual inverter power.

[0143] It should be noted that the examples and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the contents disclosed in the above embodiments. It should be noted that the above modules as part of the control circuit of the optical storage system can be implemented by software or hardware, wherein the hardware environment includes a network environment.

Claims

1. A method for controlling a photovoltaic storage system, characterized in that: The solar energy storage system control method comprises: Get the battery status parameters; adjusting the operating state of the battery according to the state parameter; The state parameter includes the battery voltage of the battery, and the step of adjusting the operating state of the battery according to the state parameter includes: Obtaining a battery voltage of the battery and a preset voltage hysteresis interval, and determining whether the battery voltage is greater than a maximum value of the voltage hysteresis interval or less than a minimum value of the voltage hysteresis interval; If the battery voltage is greater than the maximum value of the voltage hysteresis interval, the battery is controlled to discharge at the adjusted power; if the battery voltage is less than the minimum value of the voltage hysteresis interval, the battery is controlled to charge at the battery target power; if the battery voltage is within the voltage hysteresis interval, the current state of the battery is kept unchanged; The step of controlling the battery to discharge with adjusted power comprises: The battery discharge power of the battery is set to 0, and the target output power is updated to the sum of the regulated power and the MPPT power.

2. The method for controlling a photovoltaic storage system according to claim 1, characterized in that: The state parameter includes the battery voltage of the battery, and the step before controlling the battery to be charged at the battery target power also includes: Obtaining a preset adjustment coefficient, a floating charge voltage of the battery, and the battery voltage; The battery target power is calculated according to the preset adjustment coefficient, the float charge voltage and the battery voltage.

3. The method for controlling a photovoltaic storage system according to claim 1, wherein: The state parameter includes a battery voltage of the battery; and the step of adjusting the operating state of the battery according to the state parameter includes: When the photovoltaic storage system is connected to the grid, a preset over-discharge voltage is obtained, and it is determined whether the battery voltage is less than the preset over-discharge voltage; If the battery voltage is lower than the preset over-discharge voltage, charging the battery through the power grid; Obtaining a preset recovery voltage, and continuously determining whether the battery voltage is greater than the preset recovery voltage; If the battery voltage is greater than the preset recovery voltage, charging the battery through the power grid is stopped.

4. The method for controlling a photovoltaic storage system according to claim 1, wherein: The method further comprises: When the photovoltaic storage system is connected to the grid, obtaining the battery target power of the battery and the MPPT power of the MPPT controller; The target output power of the energy storage converter is obtained according to the battery target power and the MPPT power.

5. The method for controlling a photovoltaic storage system according to claim 1, wherein: The method further comprises: When the photovoltaic storage system is off-grid, obtaining the battery voltage of the battery and the actual inverter power of the energy storage converter; The target MPPT power of the MPPT controller is obtained according to the battery voltage and the actual inverter power.

6. A control circuit for a photovoltaic storage system, characterized in that: The photovoltaic storage system control circuit is applied to the photovoltaic storage system control method according to any one of claims 1 to 5, wherein the photovoltaic storage system control circuit comprises an MPPT controller, a storage battery and an energy storage inverter; the input end of the MPPT controller is connected to the solar module, the output end of the MPPT controller is respectively connected to the storage battery and the energy storage inverter, the storage battery is also connected to the energy storage inverter, the AC output end of the energy storage inverter serves as the output end of the photovoltaic storage system control circuit, the energy storage inverter comprises a central controller, and the central controller is respectively connected to the MPPT controller and the storage battery; wherein: The central controller is used to obtain the state parameters of the battery and adjust the operating state of the battery according to the state parameters.

7. A solar energy storage system, characterized in that: The photovoltaic storage system comprises a solar energy component and a photovoltaic storage system control circuit as claimed in claim 6, wherein the solar energy component is connected to the photovoltaic storage system control circuit.

8. An electronic device, characterized in that: The electronic device is applied to the control method of the photovoltaic storage system according to any one of claims 1 to 5, and the electronic device includes: The first acquisition module is used to obtain the status parameters of the MPPT controller and the battery; A first adjustment module, used for adjusting the operating state of the battery according to the state parameter; The first adjustment module includes: a first judgment unit, configured to obtain a battery voltage of the battery and a preset voltage hysteresis interval, and judge whether the battery voltage is greater than a maximum value of the voltage hysteresis interval or less than a minimum value of the voltage hysteresis interval; a first control unit, configured to control the storage battery to discharge at an adjusted power if the battery voltage is greater than a maximum value of the voltage hysteresis interval; control the storage battery to charge at a battery target power if the battery voltage is less than a minimum value of the voltage hysteresis interval; and keep the current state of the storage battery unchanged if the battery voltage is within the voltage hysteresis interval; The first control unit comprises: The first updating subunit is used to set the battery discharge power of the battery to 0, and update the target output power to the sum of the adjustment power and the MPPT power.

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