Photovoltaic inverter control method and system

Abstract

Multiple embodiments of this specification relate to the field of automation control technology, and specifically to a photovoltaic inverter control method and system. The photovoltaic inverter includes an inverter unit, an inverter relay, a mains relay, a load relay, an intelligent load relay and an inverter controller. The output end of the inverter unit is connected to the mains relay, the load relay and the intelligent load relay via the inverter relay. The inverter relay, the mains relay, the load relay and the intelligent load relay are connected to the inverter controller. The method includes the steps of: connecting the control signal end of the inverter relay to the input end of the NOT gate, respectively connecting the control signal ends of the mains relay, the load relay and the intelligent load relay to the output ends of three OR gates, respectively connecting the first input ends of the three OR gates to the inverter controller, and the second input ends of the three OR gates to the output ends of the NOT gates.

Description

Technical Field

[0001] Multiple embodiments of this specification relate to the field of automation control technology, and specifically to a photovoltaic inverter control method and system. Background Art

[0002] The photovoltaic inverter is one of the core components in the solar photovoltaic power generation system. It is mainly responsible for converting the direct current generated by the solar panel into alternating current so that it can be used by household appliances or transmitted to the power grid. There are three main types of photovoltaic inverters: off-grid photovoltaic inverters, grid-connected photovoltaic inverters, and hybrid photovoltaic inverters. Off-grid photovoltaic inverters are suitable for areas that are not connected to the public power grid or where power outages are frequent. This type of photovoltaic inverter is usually connected to a battery to store excess power for use at night or on cloudy days. Grid-connected photovoltaic inverters are suitable for households that have been connected to the public power grid. This type of photovoltaic inverter cannot continue to work when the power grid is out of power, because it may transmit power to the grid, which may cause danger to maintenance personnel. Hybrid photovoltaic inverters combine the functions of off-grid and grid-connected photovoltaic inverters. They can transmit power to the grid when there is a grid, and switch to a mode of using energy storage equipment to supply power when there is no grid.

[0003] When a photovoltaic inverter fails or the software code is upgraded, the photovoltaic inverter will stop running. If the user connects the load to the output end of the photovoltaic inverter, the photovoltaic inverter cannot supply power, which will cause the user's load to be unusable. At present, the software code is usually upgraded remotely, and it is impossible to sense whether the user's load is in use, which seriously affects the normal use of the user and poses a safety hazard. Therefore, it is necessary to improve the control technology of photovoltaic energy storage power supply so that when the photovoltaic inverter fails or the software code is upgraded, the user's load can be guaranteed to obtain normal power supply. Summary of the invention

[0004] Multiple embodiments of this specification describe a photovoltaic inverter control method and system.

[0005] In a first aspect, an embodiment of the present specification provides a photovoltaic inverter control method, wherein the photovoltaic inverter includes an inverter unit, an inverter relay, a mains relay, a load relay, an intelligent load relay, and an inverter controller, wherein the input end of the inverter unit is connected to a photovoltaic panel and a battery, and the output end of the inverter unit is connected to the mains relay, the load relay, and the intelligent load relay via the inverter relay.

[0006] The inverter relay, the mains relay, the load relay, and the intelligent load relay are connected to the inverter controller, and the method comprises the steps of:

[0007] The control signal end of the inverter relay is connected to the input end of the NOT gate, and the control signal ends of the AC power relay, the load relay and the intelligent load relay are respectively connected to the output ends of the three OR gates, the first input ends of the three OR gates are respectively connected to the inverter controller, and the second input ends of the three OR gates are all connected to the output end of the NOT gate.

[0008] In the second aspect, an embodiment of the present specification provides a photovoltaic inverter control system, wherein the photovoltaic inverter includes an inverter unit, an inverter relay, a mains relay, a load relay, an intelligent load relay and an inverter controller, wherein the inverter unit input end is connected to the photovoltaic panel and the battery, and the inverter unit output end is connected to the mains relay, the load relay and the intelligent load relay via the inverter relay, and the inverter relay, the mains relay, the load relay and the intelligent load relay are connected to the inverter controller, characterized in that it also includes a NOT gate and three OR gates, wherein the control signal end of the inverter relay is connected to the NOT gate input end, and the control signal ends of the mains relay, the load relay and the intelligent load relay are respectively connected to the output ends of the three OR gates, the first input ends of the three OR gates are respectively connected to the inverter controller, and the second input ends of the three OR gates are all connected to the output end of the NOT gate.

[0009] The beneficial effects brought by the technical solutions provided by some embodiments of this specification include at least:

[0010] In multiple embodiments of this specification, the photovoltaic inverter control method provided can realize the linkage of the photovoltaic inverter, the load relay and the mains relay. When the photovoltaic inverter fails or the program is upgraded, it can quickly switch to the mains power supply to ensure the user's electricity use and avoid the loss of the load due to power outage. By adjusting the working state of the supercapacitor and the battery, the role of helping to reduce the peak and fill the valley is achieved. During the valley period of the mains power, the battery is used for charging, and the user's load is powered during the peak period. The use of supercapacitors can smooth the fluctuations in the output of the photovoltaic panel, stabilize the power supply of the photovoltaic inverter, and improve the safety of electricity use.

[0011] Other features and advantages of the various embodiments of the present specification will be further disclosed in the following detailed description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of this specification, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1A schematic diagram of an application scenario of the photovoltaic inverter control method provided in the embodiments of this specification.

[0014] Figure 2 A schematic diagram of the power supply relationship of the photovoltaic energy storage power supply system provided in the embodiments of this specification.

[0015] Figure 3 This is a schematic diagram of photovoltaic inverter control connection in the prior art.

[0016] Figure 4 This is a schematic diagram of the photovoltaic inverter control connection provided in the embodiments of this specification. DETAILED DESCRIPTION

[0017] The following is an explanation and description of the technical solutions of the embodiments of this specification in conjunction with the drawings of the embodiments of this specification, but the following embodiments are only preferred embodiments of this specification, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of this specification.

[0018] The terms "first", "second", "third", etc. in the description and claims of this specification and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0019] In the following description, terms such as "inside", "outside", "up", "down", "left", "right", etc. that indicate directions or positional relationships are only used to facilitate the description of the embodiments and simplify the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation of this specification.

[0020] The data involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection of relevant data complies with the relevant laws, regulations and standards of relevant countries and regions.

[0021] As climate change becomes more serious, people are paying more attention to environmental protection. Using solar energy as an alternative energy source can help reduce greenhouse gas emissions and fight global warming. Figure 1Rooftop photovoltaic system refers to a solar photovoltaic power generation system installed on the roof of a building. It uses solar energy to convert into electrical energy to provide clean and renewable energy for the building. With the development of photovoltaic technology, the efficiency of solar panels has been continuously improved, while the production cost has been gradually reduced, making rooftop photovoltaic systems gradually feasible and effective. The growing demand for sustainable energy has promoted rooftop photovoltaic systems to gradually become one of the important ways for households and enterprises to save energy and reduce emissions. Moreover, for remote areas or places where the mains 20 is unstable, the rooftop photovoltaic system can provide a stable power supply and increase energy independence. The photovoltaic energy storage power supply system generally includes a photovoltaic panel 10, an equipment cabinet 30, a photovoltaic inverter 40 and a control device. The equipment cabinet 30 is provided with a battery 31, a mains relay 44, and a load relay 46. The photovoltaic inverter 40 is also arranged in the equipment cabinet 30.

[0022] Please refer to the attached Figure 2 , showing a schematic diagram of the power supply relationship of the photovoltaic energy storage power supply system. The inverter unit 42 is externally connected to ports including photovoltaic panels 10, batteries 31, mains 20, loads 50 and smart loads 60 or diesel generators 61. The battery 31 and the inverter unit 42 can perform bidirectional energy interaction through DC / DC conversion, that is, the charging and discharging of the battery 31. The photovoltaic panel 10, as a unidirectional DC / DC, realizes the power generation function through the MPPT control of the inverter unit 42. The mains 20 can realize the purchase and sale of electricity by converting with the inverter unit 42, and can charge and discharge the battery 31 to realize the function of peak shaving and valley filling. The photovoltaic panel 10 and the battery 31 can supply power to the load 50 and the smart load 60 through the inverter unit 42. In addition, the battery 31 can also be used as a backup power supply to supply power to important loads 50 in the absence of photovoltaic panels 10 and mains 20, thereby realizing the function of uninterruptible power supply. Attached Figure 2 The direction of the arrow in the figure indicates the direction of energy flow of the port. A single arrow indicates that energy can only flow in one direction, and a double arrow indicates that energy can flow in both directions. The inverter unit 42 internally integrates the DC / DC conversion of the photovoltaic panel 10 and the DC / DC conversion of the battery 31, as well as the DC / AC conversion to the mains 20 and the load 50, the smart load 60 or the generator 61. The energy management and control are automatically performed through the above conversion and energy management system.

[0023] The control of the photovoltaic inverter 40 is a key link to ensure the efficient and stable operation of the inverter. The output power of the photovoltaic panel 10 will be affected by factors such as light intensity and temperature, so it is necessary to dynamically adjust the working point to obtain the maximum energy output. The MPPT algorithm can detect the voltage and current characteristics of the photovoltaic array in real time, and adjust the working point of the inverter so that it is always near the maximum power point, thereby maximizing the utilization of solar energy. In order to ensure the safety of the inverter and its connected equipment, the photovoltaic inverter 40 usually has a variety of protection functions, such as overcurrent protection, overvoltage protection, undervoltage protection, overtemperature protection, etc. When an abnormal situation is detected, the inverter will automatically shut down or adjust the working state to prevent damage to the equipment or cause a safety accident. However, if the user's load 50 is connected to the output end of the photovoltaic inverter 40 at this time, it will cause the load 50 to be powered off, which may cause damage to the load 50 and even bring safety risks. If the power supply is to be restored, the user's load 50 needs to be connected to the mains 20, and this process currently requires manual participation.

[0024] Photovoltaic inverter 40, photovoltaic energy storage inverter and energy storage inverter, etc., in order to further optimize the software code, the system will be remotely upgraded. During the process, due to the long time of remote upgrade and for safety reasons, the photovoltaic inverter 40 will stop running. This will affect the actual use and experience of the user. If the user connects the load 50 to the load 50 side of the photovoltaic inverter 40, when upgrading, the load 50 side of the photovoltaic inverter 40 cannot be powered, and the load 50 cannot be used. Moreover, usually during remote and off-site upgrades, it is impossible to judge the actual use of the user's load 50, and it is difficult to avoid affecting the normal use of the user.

[0025] In order to be able to bypass the power supply when the mains 20 is available, the photovoltaic inverter 40 can supply power to the load 50 in a bypass manner when the mains 20 is available. After the system upgrade is completed, it is switched to the normal working mode. At present, due to safety considerations and other reasons, the inverter controller 41 generally has a main MCU and an auxiliary MCU. When the photovoltaic inverter 40 is upgraded, bypass control can be performed through the auxiliary MCU. However, if the auxiliary MCU is also upgraded at the same time, bypass control cannot be achieved, and bypass power supply cannot be achieved.

[0026] In order to completely solve the bypass power supply problem, without adding more relays and without bypass control of the relays through the main MCU and the auxiliary MCU, it is necessary to study a new circuit or method to solve the problem of bypassing the AC power 20 to supply power to the load 50 of the inverter.

[0027] Since this application involves some professional terms, these professional terms will be introduced below.

[0028] Battery 31

[0029] Batteries 31 are an important part of solar photovoltaic systems or other renewable energy systems. They are mainly used to store excess electricity so that it can be released when needed. Batteries 31 can be divided into many types according to their chemical composition, purpose and design, among which the most common is lead-acid batteries. Lead-acid batteries are one of the earliest and most common types of batteries 31. They are relatively low in cost, but they are heavy, large in size, and have a relatively short cycle life.

[0030] Photovoltaic inverter 40

[0031] The photovoltaic inverter 40 is one of the core components in the solar photovoltaic power generation system. It is responsible for converting the direct current generated by the solar panel into alternating current so that it can be supplied to household appliances or connected to the mains 20. The selection and performance of the photovoltaic inverter 40 directly affect the efficiency and reliability of the entire solar energy system. The photovoltaic inverter 40 recorded in this specification belongs to the type of photovoltaic inverter 40 or photovoltaic energy storage inverter. The photovoltaic energy storage inverter has the functions of an ordinary photovoltaic inverter 40 and can also be used in combination with a battery energy storage system. The photovoltaic energy storage inverter can store electrical energy when there is excess solar power and release it for users at night or on cloudy days. It can be used in off-grid systems or hybrid systems to ensure the stability of power supply.

[0032] Relay

[0033] A relay is an electrical control device, usually used to control a large current circuit through a small current circuit. Relays are widely used in electrical systems. They can be used for switching circuits, safety protection, signal conversion and other purposes.

[0034] NOT Gate

[0035] The NOT gate is one of the most basic logic gates in digital logic circuits. It has only one input and one output. The function of the NOT gate is to perform a logical inversion operation on the input signal, that is, if the input is high, the output is low; if the input is low, the output is high.

[0036] OR Gate

[0037] An OR gate is a logic gate that accepts one or more input signals and generates an output signal based on these inputs. For an OR gate, the output is high as long as one of the inputs is high (usually represented by logic "1"); the output is low only when all inputs are low (usually represented by logic "0").

[0038] Comparative Example

[0039] Please refer to the attached Figure 3, which is a schematic diagram of control signal connection and AC power supply connection of a photovoltaic inverter 40 disclosed in the art.

[0040] The inverter converts the DC / AC output, the inverter relay 43 works, and then the load relay 46 and the intelligent load relay 45 work. Then, when the mains 20 has power, sampling and phase locking are performed to judge, and the control mode is converted. The mains relay 44 is energized, and the inverter conversion is converted from the voltage source mode to the current source mode to work.

[0041] In this control mode, when the main MCU and the auxiliary MCU of the inverter controller 41 are upgraded, the main MCU and the auxiliary MCU are in a stopped working state, all outputs are not working, and are in a protection state. At this time, all relays are in a disconnected state, and the load 50 cannot be powered normally. After the inverter controller 41 is upgraded, the inverter controller 41 will resume normal mode to work, and the load 50 will be powered again and work normally. There is a problem of unstable power supply to the load 50. Example

[0042] This specification first provides a control method for a photovoltaic inverter 40, wherein the photovoltaic inverter 40 includes an inverter unit 42, an inverter relay 43, a mains relay 44, a load relay 46, an intelligent load relay 45 and an inverter controller 41, wherein the input end of the inverter unit 42 is connected to the photovoltaic panel 10 and the battery 31, and the output end of the inverter unit 42 is connected to the mains relay 44, the load relay 46 and the intelligent load relay 45 via the inverter relay 43.

[0043] The inverter relay 43, the mains relay 44, the load relay 46, and the intelligent load relay 45 are connected to the inverter controller 41, and the method comprises the steps of:

[0044] The control signal end of the inverter relay 43 is connected to the input end of the NOT gate, and the control signal ends of the AC power relay 44, the load relay 46 and the intelligent load relay 45 are respectively connected to the output ends of the three OR gates, the first input ends of the three OR gates are respectively connected to the inverter controller 41, and the second input ends of the three OR gates are all connected to the output end of the NOT gate.

[0045] The mains 20, the load 50, the smart load 60 or the generator 61 are connected via a relay. When the inverter controller 41 performs a system upgrade, the photovoltaic inverter 40 does not output, and the inverter relay 43 of the photovoltaic inverter 40 is disconnected, so that the mains relay 44 and the load relay 46 or the smart load relay 45 can be kept normally attracted, and the bypass mode can be realized, and the mains 20 is connected to the load 50 via the bypass to supply power to the load 50.

[0046] In this embodiment, through the NOT gate and OR gate logic circuit, when the inverter relay 43 of the photovoltaic inverter 40 is disconnected, the AC power relay 44 and the load relay 46 or the SMARTLOAD relay are powered through the NOT gate and OR gate to ensure the normal operation of these relays and realize the bypass power supply function.

[0047] The time for the relay to be closed is generally greater than 10ms, and the time for the relay to be released is about 4ms. During the process of switching the working state of the relay, the control signal is sent out at the same time, and there is a delay in reaching the relay after being processed by the NOT gate and OR gate logic circuit. Since the release time of the relay is short and the closing time is long, the ordinary state switching is first disconnected and then connected, with a time delay of more than 5ms in between. The delay of the control signal is generally microseconds or shorter, which is much less than the delay of 5ms. Therefore, in this embodiment, the delay time of the signal switching will not cause the relay to be disconnected, and the relay will always remain closed, which has no effect on the operation of the relay.

[0048] When the photovoltaic inverter 40 is in working state, a 1 signal is applied to the control signal ends of the inverter relay 43, the AC power relay 44 and the load relay 46. Under the action of the NOT gate and the OR gate, a 1 signal is applied to the control signal ends of the AC power relay 44 and the load relay 46, so as to realize adaptive protection that the load 50 is powered by the photovoltaic inverter 40 and the AC power 20.

[0049] After adding bypass power supply, it is necessary to ensure that the working mode under normal conditions is not affected, and the working logic and control mode of the entire system need to be changed to meet the normal operation of the system in different modes and the normal operation during upgrade. Specifically, it includes enumerating the working state of the inverter unit 42, listing the controllable states of the AC relay 44, load relay 46, and intelligent load relay 45 under each working state; and controlling the AC relay 44, load relay 46, and intelligent load relay 45 according to the controllable state.

[0050] Table 1 Working status table

[0051]

[0052] During the startup, connection, normal operation, upgrade, and failure shutdown of the photovoltaic inverter 40, the working states of the inverter relay 43, the mains relay 44, and the load relay 46 in the photovoltaic inverter 40 are shown in Table 1. Table 1 also records whether the mains relay 44 and the load relay 46 can accurately respond to the state of the inverter controller 41, that is, whether they are controlled by the inverter controller 41. Specifically, the following situations are included:

[0053] The photovoltaic inverter 40 starts working normally. When the photovoltaic inverter 40 has no output, the inverter relay 43 is disconnected, and the mains relay 44 and the intelligent load relay 45 or the load relay 46 are in a closed state.

[0054] When the photovoltaic inverter 40 is started up and starts to output, the inverter relay 43 is closed, and the mains relay 44 and the intelligent load relay 45 or the load relay 46 are closed.

[0055] When operating off-grid, the opening and closing of the mains relay 44 will not affect the household load 50 (in this case, the load 50 cannot work before the photovoltaic inverter 40 is turned on and outputs, such as when it is temporarily powered by photovoltaic power). When operating on-grid, the mains 20 first supplies power to the load 50, and after the photovoltaic inverter 40 works normally, it switches to the photovoltaic inverter 40 for power supply.

[0056] When the photovoltaic inverter 40 outputs, the control signal of the inverter relay 43 is high level effective, and other relays are still closed under the control of the OR gate logic to ensure normal power supply to the load. At this time, the photovoltaic inverter 40 is controlled according to the normal control logic.

[0057] When the program of the photovoltaic inverter 40 is upgraded, the main MCU of the photovoltaic inverter 40 controls the photovoltaic inverter 40 to stop working, and the control signal of the inverter relay 43 becomes a low level, which is converted into a high level through the action of the NOT gate, so that the AC power relay 44 is closed, and the intelligent load relay 45 or the load relay 46 is closed, thereby automatically switching the household load 50 to the AC power supply 20.

[0058] When the photovoltaic inverter 40 fails and stops, the photovoltaic inverter 40 has no output, and the main MCU of the photovoltaic inverter 40 controls the photovoltaic inverter 40 to stop working. The control signal of the inverter relay 43 becomes a low level and is converted to a high level through the action of the NOT gate, so that the AC power relay 44 is closed and the intelligent load relay 45 or the load relay 46 is closed.

[0059] It can be seen that, through the above logic control method, the technical solution recorded in this embodiment can not only meet the normal operation of the user's load 50 when the power grid has power during the photovoltaic inverter 40 upgrade process, but also can automatically bypass the power grid to supply power to the load 50 in the event of a fault through the control logic. The technical solution recorded in this embodiment can ensure that the user's load 50 can obtain power reliably. Compared with the photovoltaic inverter 40 currently on the market, the solution recorded in this embodiment can improve the reliability of the power supply to the load 50.

[0060] On the other hand, in another embodiment, when the photovoltaic inverter 40 performs a system upgrade, the following steps are performed:

[0061] Detect whether the mains 20 has power, and when the mains 20 has power, set the upgrade flag position of the photovoltaic inverter 40 to 1;

[0062] Detecting whether the photovoltaic inverter 40 is currently in a working state;

[0063] If the photovoltaic inverter 40 is not in working state, the control signal end of the inverter relay 43 is in 0 signal state, and under the action of the NOT gate, the control signal ends of the mains relay 44, the intelligent load relay 45 and the load relay 46 are applied with 1 signal, ensuring that the load 50 is powered by the mains 20;

[0064] If the photovoltaic inverter 40 is in working state, a 1 signal is applied to the control signal end of the inverter relay 43. Under the action of the NOT gate and the OR gate, a 1 signal is applied to the control signal end of the AC relay 44, the intelligent load relay 45 and the load relay 46, so as to ensure that the load 50 is powered by the photovoltaic inverter 40 and the AC power 20.

[0065] Performing a system upgrade, if the photovoltaic inverter 40 is in a working state before the system upgrade, after the system upgrade is completed, the photovoltaic inverter 40 is started according to a preset process, and after the photovoltaic inverter 40 is started, the upgrade flag is set to 0.

[0066] On the other hand, in another embodiment, the method of starting the photovoltaic inverter 40 according to a preset process includes:

[0067] At the start-up moment, the inverter controller 41 applies a 0 signal to the control signal terminals of the inverter relay 43, the mains relay 44 and the load relay 46. Under the action of the NOT gate and the OR gate, the mains relay 44 and the load relay 46 are closed to ensure that the load 50 is powered by the mains 20.

[0068] During the startup process, the output voltage of the photovoltaic inverter 40 is gradually increased to a target voltage;

[0069] The inverter controller 41 applies a 1 signal to the control signal terminals of the inverter relay 43 , the AC power relay 44 and the load relay 46 . Under the action of the NOT gate and the OR gate, the AC power relay 44 and the load relay 46 are closed, and the load 50 is powered by the photovoltaic inverter 40 .

[0070] On the other hand, the present specification provides a photovoltaic inverter 40 control system, the photovoltaic inverter 40 includes an inverter unit 42, an inverter relay 43, a mains relay 44, a load relay 46, an intelligent load relay 45 and an inverter controller 41, the input end of the inverter unit 42 is connected to the photovoltaic panel 10 and the battery 31, the output end of the inverter unit 42 is connected to the mains relay 44, the load relay 46 and the intelligent load relay 45 via the inverter relay 43, the inverter relay 43, the mains relay 44, the load relay 46, the intelligent load relay 45 are connected to the inverter controller 41, and is characterized in that it also includes a NOT gate and three OR gates, the control signal end of the inverter relay 43 is connected to the NOT gate input end, the control signal ends of the mains relay 44, the load relay 46 and the intelligent load relay 45 are respectively connected to the output ends of the three OR gates, the first input ends of the three OR gates are respectively connected to the inverter controller 41, and the second input ends of the three OR gates are all connected to the output end of the NOT gate.

[0071] On the other hand, in another embodiment, the inverter controller 41 enumerates the working status of the inverter unit 42, lists the controllable states of the AC power relay 44, the load relay 46, and the intelligent load relay 45 under each working state, and the inverter controller 41 controls the AC power relay 44, the load relay 46, and the intelligent load relay 45 according to the controllable states.

[0072] On the other hand, in another embodiment, when the photovoltaic inverter 40 performs a system upgrade, the inverter controller 41 performs the following steps:

[0073] Detect whether the mains 20 has power, and when the mains 20 has power, set the upgrade flag position of the photovoltaic inverter 40 to 1;

[0074] Detecting whether the photovoltaic inverter 40 is currently in a working state;

[0075] If the photovoltaic inverter 40 is not in working state, the control signal end of the inverter relay 43 is in 0 signal state, and under the action of the NOT gate, the control signal ends of the mains relay 44, the intelligent load relay 45 and the load relay 46 are applied with 1 signal, ensuring that the load 50 is powered by the mains 20;

[0076] If the photovoltaic inverter 40 is in working state, a 1 signal is applied to the control signal end of the inverter relay 43. Under the action of the NOT gate and the OR gate, a 1 signal is applied to the control signal end of the AC relay 44, the intelligent load relay 45 and the load relay 46, so as to ensure that the load 50 is powered by the photovoltaic inverter 40 and the AC power 20.

[0077] Performing a system upgrade, if the photovoltaic inverter 40 is in a working state before the system upgrade, after the system upgrade is completed, the photovoltaic inverter 40 is started according to a preset process, and after the photovoltaic inverter 40 is started, the upgrade flag is set to 0.

[0078] On the other hand, in another embodiment, when starting according to a preset process, the inverter controller 41 performs the following steps:

[0079] At the start-up moment, the inverter controller 41 applies a 0 signal to the control signal terminals of the inverter relay 43, the mains relay 44 and the load relay 46. Under the action of the NOT gate and the OR gate, the mains relay 44 and the load relay 46 are closed to ensure that the load 50 is powered by the mains 20.

[0080] During the startup process, the output voltage of the photovoltaic inverter 40 is gradually increased to a target voltage;

[0081] The inverter controller 41 applies a 1 signal to the control signal terminals of the AC power relay 44 and the load relay 46. Under the action of the NOT gate and the OR gate, the AC power relay 44 and the load relay 46 are closed to feed power to the grid and ensure power supply to the load.

[0082] The embodiments described above are merely preferred embodiments of this specification and are not intended to limit the scope of this specification. Without departing from the design spirit of this specification, various modifications and improvements made to the technical solutions of this specification by ordinary technicians in this field should fall within the scope of protection determined by the claims of this specification.

Claims

1. A photovoltaic inverter control method, wherein the photovoltaic inverter comprises an inverter unit, an inverter relay, a mains relay, a first load relay, an intelligent load relay and an inverter controller, wherein the inverter unit input end is connected to a photovoltaic panel and a battery, and the inverter unit output end is connected to the mains relay, the first load relay and the intelligent load relay via the inverter relay, The inverter relay, the mains relay, the first load relay, and the intelligent load relay are connected to the inverter controller, characterized in that: The method comprises the steps of: Connect the control signal end of the inverter relay to the input end of the NOT gate, respectively connect the control signal ends of the mains relay, the first load relay and the intelligent load relay to the output ends of the three OR gates, the first input ends of the three OR gates are respectively connected to the inverter controller, and the second input ends of the three OR gates are all connected to the output end of the NOT gate; When the photovoltaic inverter is undergoing a system upgrade, the following steps are performed: Detect whether the mains power is on, and when the mains power is on, set the upgrade flag position of the photovoltaic inverter to 1; Detecting whether the photovoltaic inverter is currently in working state; If the photovoltaic inverter is not in working state, the control signal end of the inverter relay is in 0 signal state, and under the action of the NOT gate and the OR gate, the control signal ends of the AC power relay, the intelligent load relay and the first load relay are applied with 1 signal to ensure that the load is powered by the AC power; If the photovoltaic inverter is in working state, a 0 signal is applied to the control signal end of the inverter relay, and under the action of the NOT gate and the OR gate, a 1 signal is applied to the control signal end of the AC power relay, the intelligent load relay and the first load relay, so as to ensure that the load is powered by the AC power; Performing a system upgrade, if the photovoltaic inverter is in a working state before the system upgrade, then after the system upgrade is completed, starting the photovoltaic inverter according to a preset process, and after the photovoltaic inverter is started, setting the upgrade flag position to 0; The method for starting the photovoltaic inverter according to a preset process includes: At the start-up moment, the inverter controller applies a 0 signal to the control signal terminals of the inverter relay, the mains relay and the first load relay. Under the action of the NOT gate and the OR gate, the mains relay and the first load relay are closed to ensure that the load is powered by the mains; During the startup process, the output terminal voltage of the photovoltaic inverter is gradually increased to a target voltage; The inverter controller applies a 1 signal to the control signal terminals of the inverter relay, the AC power relay and the first load relay. Under the action of the NOT gate and the OR gate, the AC power relay and the first load relay remain closed to feed power to the grid and ensure power supply to the load.

2. A photovoltaic inverter control method according to claim 1, characterized in that: The method further comprises the steps of: Enumerate the working states of the inverter unit, and list the controllable states of the mains relay, the first load relay, and the intelligent load relay under each working state; The mains relay, the first load relay and the intelligent load relay are controlled according to the controllable state.

3. A photovoltaic inverter control method according to claim 1 or 2, characterized in that: When the photovoltaic inverter is in working state, a 1 signal is applied to the control signal ends of the inverter relay, the AC power relay and the first load relay. Under the action of the NOT gate and the OR gate, a 1 signal is applied to the control signal ends of the AC power relay and the first load relay, thereby realizing adaptive protection that the load is powered by the AC power.

4. A photovoltaic inverter control method according to claim 1, characterized in that: When the photovoltaic inverter is connected to the grid, the following steps are performed: When it is determined that the upgrade flag is 0 and it is detected that the mains power is available, phase locking is performed; When the phase locking is completed, a 1 signal is applied to the control signal terminals of the inverter relay, the mains relay and the first load relay. Under the action of the OR gate, the mains relay and the first load relay are closed to feed power to the grid and ensure power supply to the load.

5. A photovoltaic inverter control system, the photovoltaic inverter comprises an inverter unit, an inverter relay, a mains relay, a first load relay, an intelligent load relay and an inverter controller, the inverter unit input end is connected to the photovoltaic panel and the battery, the inverter unit output end is connected to the mains relay, the first load relay and the intelligent load relay via the inverter relay, the inverter relay, the mains relay, the first load relay, the intelligent load relay are connected to the inverter controller, characterized in that: It also includes a NOT gate and three OR gates, the control signal end of the inverter relay is connected to the input end of the NOT gate, the control signal ends of the mains relay, the first load relay and the intelligent load relay are respectively connected to the output ends of the three OR gates, the first input ends of the three OR gates are respectively connected to the inverter controller, and the second input ends of the three OR gates are all connected to the output end of the NOT gate; When the photovoltaic inverter is undergoing system upgrade, the inverter controller performs the following steps: Detect whether the mains power is on, and when the mains power is on, set the upgrade flag position of the photovoltaic inverter to 1; Detecting whether the photovoltaic inverter is currently in working state; If the photovoltaic inverter is not in working state, the control signal end of the inverter relay is in 0 signal state, and under the action of the NOT gate and the OR gate, the control signal ends of the AC power relay, the intelligent load relay and the first load relay are applied with 1 signal to ensure that the load is powered by the AC power; If the photovoltaic inverter is in working state, a 0 signal is applied to the control signal end of the inverter relay, and under the action of the NOT gate and the OR gate, a 1 signal is applied to the control signal end of the AC power relay, the intelligent load relay and the first load relay, so as to ensure that the load is powered by the AC power; Performing a system upgrade, if the photovoltaic inverter is in a working state before the system upgrade, then after the system upgrade is completed, starting the photovoltaic inverter according to a preset process, and after the photovoltaic inverter is started, setting the upgrade flag position to 0; When starting according to the preset process, the inverter controller performs the following steps: At the start-up moment, the inverter controller applies a 0 signal to the control signal terminals of the inverter relay, the mains relay and the first load relay. Under the action of the NOT gate and the OR gate, the mains relay and the first load relay are closed to ensure that the load is powered by the mains; During the startup process, the output terminal voltage of the photovoltaic inverter is gradually increased to a target voltage; The inverter controller applies a 1 signal to the control signal terminals of the inverter relay, the AC power relay and the first load relay. Under the action of the NOT gate and the OR gate, the AC power relay and the first load relay remain closed to feed power to the grid and ensure power supply to the load.

6. A photovoltaic inverter control system according to claim 5, characterized in that: The inverter controller enumerates the working status of the inverter unit, lists the controllable states of the AC power relay, the first load relay, and the intelligent load relay under each working status, and the inverter controller controls the AC power relay, the first load relay, and the intelligent load relay according to the controllable states.

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