Anti-countercurrent energy-saving power supply system mainly based on photovoltaic and flexibly supplemented by grid power and power supply method thereof

Abstract

The invention discloses an anti-countercurrent energy-saving power supply system mainly based on photovoltaic and flexibly supplemented by grid power, which comprises a photovoltaic power generation assembly, the photovoltaic power generation assembly is connected with a photovoltaic / grid power direct-current grid-connected module, and the photovoltaic / grid power direct-current grid-connected module is further connected with a grid power voltage regulation rectifier module and a power taking control switch. The power output side of the photovoltaic / grid power direct-current grid-connected module is sequentially connected with a direct-current filtering module, a sine wave inverter and an alternating-current filtering and voltage-stabilizing module, the alternating-current filtering and voltage-stabilizing module is connected to a load electric appliance, and the power supply system further comprises a main controller and an operation module which are used for controlling a power supply mode and power utilization safety. According to the invention, photovoltaic electric energy can be fully utilized to the greatest extent, an electric energy utilization concept of taking photovoltaic as a main part and taking grid power as an auxiliary part is realized, countercurrent prevention is realized through cooperation of the isolation diode and the grid power voltage regulation rectification module, intelligent flexible supplement of the grid power can be realized, and healthy development of the photovoltaic industry is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a backflow-proof energy-saving power supply system with photovoltaic as the main power source and grid electricity as the flexible supplement. Background Art

[0002] Photovoltaic power generation is an important technology for green, low-carbon and new energy power generation. After nearly ten years of development, it has been widely installed and applied in many scenarios, reducing electricity costs for enterprises, making great contributions to social energy conservation and carbon reduction, and improving the human living environment. However, it also has the following disadvantages:

[0003] 1. The ideal application mode of existing photovoltaic power generation is to connect to the grid and operate in AC mode. Traditional photovoltaic inverters can only adjust the inverter output by detecting the grid voltage and phase sequence to make the voltage always higher than the grid voltage, so as to achieve the priority utilization of photovoltaic power generation. In the past two years, due to the impact of economic development, the power consumption of high-energy-consuming enterprises has dropped sharply, and photovoltaic power generation is seriously surplus during the day, resulting in a continuous increase in grid voltage, causing the risk of critical paralysis and damage to the grid and power-consuming equipment, which has brought severe challenges to the State Grid. At present, it can only be encouraged and guided by participating in peak-shaving and peak-valley electricity prices to absorb photovoltaic green electricity during the day, which has caused great waste and affected the development of the photovoltaic industry.

[0004] 2. Since the technology of connecting traditional photovoltaic inverters to the grid power supply is relatively high and the handling procedures are complicated, it is difficult for small-scale photovoltaic power generation that does not meet the safety grid connection requirements to be connected to the grid. Independent photovoltaic power generation systems are greatly affected by the weather and cannot independently and reliably provide stable electricity, which affects the promotion and application of photovoltaic power generation in small-scale power supply systems.

[0005] 3. Due to the problem of excess electricity consumption during the day, many areas have strictly prohibited the installation of new photovoltaic power stations. Small and medium-sized anti-reverse current photovoltaic off-grid power stations have emerged. Anti-reverse current photovoltaic off-grid power stations are systems that can operate independently of the power grid. This type of system uses photovoltaic power only to supply local loads. The direction and size of the current are monitored in real time through anti-reverse current technology. When abnormal reverse flow is detected, the circuit is quickly cut off or adjusted to prevent it from being fed into the power grid, so as to maintain the stability and safety of the power system.

[0006] In fact, because existing traditional photovoltaic inverters are all connected to the grid in AC mode, they cannot completely prevent reverse flow, which still causes peak load difficulties and safety hazards to the power grid. Traditional photovoltaic power stations can only be connected to the grid, and cannot be operated off-grid, nor can they be used with many special equipment for energy-saving supplements. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a photovoltaic-based, grid-powered, flexibly supplemented anti-backflow energy-saving power supply system that uses photovoltaic power generation as the main power source for load electricity consumption and the power grid to flexibly supplement load electricity consumption in a timely, intelligent and timely manner to ensure the safety and reliability of the power grid and power-consuming equipment.

[0008] In order to solve the above technical problems, the technical solution of the present invention is: a photovoltaic-based, grid-powered flexible supplementary anti-backflow energy-saving power supply system, including a photovoltaic power generation component, the power output end of the photovoltaic power generation component is connected to a photovoltaic / grid-powered DC grid-connected module, the photovoltaic / grid-powered DC grid-connected module is also connected to a grid-powered voltage regulating and rectifying module, the grid-powered voltage regulating and rectifying module is connected to the grid line of the State Grid, and the grid-powered voltage regulating and rectifying module is connected to a power taking control switch on the power taking line, the power output side of the photovoltaic / grid-powered DC grid-connected module is sequentially connected to a DC filter module, a sine wave inverter, and an AC filter and voltage stabilizing module, the AC filter and voltage stabilizing module is connected to a load electrical appliance, and also includes a main controller for controlling the power supply mode and power safety, the main controller is respectively connected to the photovoltaic / grid-powered DC grid-connected module, the grid-powered voltage regulating and rectifying module, the power taking control switch, the sine wave inverter, the AC filter and voltage stabilizing module and the operation module.

[0009] As a preferred technical solution, the photovoltaic power generation components are provided in several groups and arranged in parallel, each of the photovoltaic power generation components is provided with several photovoltaic power generation panels, and the photovoltaic power generation panels in the same group are arranged in series in sequence and respectively form a positive electrode and a negative electrode of the power generation component.

[0010] As a preferred technical solution, the photovoltaic / grid power DC grid-connected module includes a positive bus and a negative bus, a plurality of positive terminals are arranged on the positive bus, a plurality of negative terminals are arranged on the negative bus, the positive poles of each of the power generation components are respectively connected to the corresponding positive terminals through wires, each of the wires is respectively connected in series with an isolation diode, the negative poles of each of the power generation components are respectively electrically connected to the corresponding negative terminals, the grid power voltage regulating rectifier module is connected between one of the positive terminals and one of the negative terminals, and the positive bus and the negative bus are also respectively electrically connected to the input end of the DC filter module.

[0011] As a preferred technical solution, the power output end of the sinusoidal wave inverter is connected to three inverter phase lines and one inverter neutral line, and the AC filtering and voltage stabilizing module includes AC filtering inductors respectively connected in series on each of the inverter phase lines, and AC filtering capacitors respectively connected between the inverter phase lines and the inverter neutral line corresponding to the power output end of the AC filtering inductor.

[0012] As a preferred technical solution, the power output end of the sine wave inverter is connected to three inverter phase lines and one inverter neutral line, and the AC filtering and voltage stabilizing module includes AC filtering capacitors respectively connected between each of the inverter phase lines and the inverter neutral line.

[0013] As a preferred technical solution, an output solid-state relay is connected between the AC filtering and voltage stabilizing module and the load electrical appliance, and the output solid-state relay is connected to the main controller.

[0014] As a preferred technical solution, the load electrical appliances are connected to the power grid line through three direct supply phase lines and one direct supply neutral line, and isolation switches, automatic reclosing switches and bypass solid-state relays are provided in sequence on the direct supply phase lines and the direct supply neutral lines along the direction of power supply, and the grid power voltage regulating and rectifier module draws power from the line between the automatic reclosing switch and the bypass solid-state relay.

[0015] As a preferred technical solution, a grid power parameter acquisition module for collecting grid power parameters is provided on the power intake side of the grid power voltage regulating and rectifier module, and an inverter parameter acquisition module for collecting power supply parameters is provided on the power output side of the AC filtering and voltage stabilizing module, and the grid power parameter acquisition module and the inverter parameter acquisition module are respectively connected to the main controller.

[0016] The present invention also relates to a power supply method for a photovoltaic-based, grid-powered flexible power supply system with anti-backflow energy-saving power supply, comprising:

[0017] Photovoltaic power supply mode

[0018] The main controller obtains the power supply information of the photovoltaic power generation component, and the main controller also obtains the power consumption information of the load electrical appliance, and processes and compares the power supply information with the power consumption information;

[0019] When the power supply information is greater than the power consumption information, the main controller controls the power taking control switch to remain in an off state, and the electric energy generated by the photovoltaic power generation assembly is converted into alternating current after passing through the photovoltaic / grid power DC grid-connected module, the DC filter module, and the sine wave inverter, and is provided to the load electrical appliance after voltage stabilization processing by the AC filter voltage stabilization module;

[0020] When the power supply information is less than the power consumption information, the main controller controls the system to enter a grid power flexible supplementary power supply mode;

[0021] Flexible supplementary power supply mode of grid electricity

[0022] The main controller calculates and obtains power shortage information, and controls the power taking control switch to close;

[0023] The AC power of the grid line is converted into DC power through the grid power voltage regulating and rectifying module, and sent to the photovoltaic / grid power DC grid-connected module to converge the DC power provided by the photovoltaic power generation component, and the power shortage calculated by the main controller is supplemented. Under the action of the isolation diodes and the grid power voltage regulating and rectifying modules respectively connected in series on each of the wires, the DC power sent by the photovoltaic power generation component and the grid power voltage regulating and rectifying module can only be converged in the photovoltaic / grid power DC grid-connected module and enter the DC filtering module, and will not flow back to the grid line, thereby realizing anti-backflow protection for the grid line.

[0024] As an improvement to the above technical solution, the power supply method further includes:

[0025] Grid power supply mode

[0026] The low power information of the photovoltaic power generation component is preset in the main controller through the operation module. When the main controller learns that the power supply information of the photovoltaic power generation component is lower than the low power information, the power supply control switch is in an off state, the bypass solid-state relay is controlled to be closed, and the output solid-state relay is controlled to be disconnected, so that the power grid line is used to directly power the load electrical appliances.

[0027] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0028] 1. It can make full use of photovoltaic power to the maximum extent and realize the concept of electricity utilization with photovoltaic power as the main and grid power as the auxiliary, which is more in line with the current basic national policy of encouraging the use of renewable energy.

[0029] 2. Through the cooperation of isolation diodes and grid power voltage regulating and rectifier modules, backflow prevention can be achieved, and at the same time, intelligent and flexible supplement of grid power can be realized. When there is sufficient sunlight, it can operate stably off the grid, which improves the power utilization efficiency, ensures the safety of electrical equipment, and solves the relevant technical defects in contact-type hard switching.

[0030] 3. It completely solves the technical difficulties of preventing backflow in traditional off-grid photovoltaic power stations, which is conducive to the healthy development of the photovoltaic industry.

[0031] 4. The wide range of application scenarios provides huge space for the later development of photovoltaic energy-saving products, thus contributing to low-carbon development. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0033] in:

[0034] Figure 1 is a structural block diagram of an embodiment of the present invention;

[0035] Figure 2 is a circuit schematic diagram of an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the connection of some peripheral circuits of the main controller according to an embodiment of the present invention;

[0037] In the figure: 1- photovoltaic power generation component; 2- photovoltaic / grid power DC grid-connected module; 3- grid power voltage regulation and rectification module; 4- DC filter module; 5- sine wave inverter; 6- AC filter voltage stabilization module. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and examples. In the following detailed description, certain exemplary embodiments of the present invention are described only by way of illustration. Needless to say, those of ordinary skill in the art will recognize that the described embodiments may be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the drawings and description are illustrative in nature and are not intended to limit the scope of protection of the claims.

[0039] like Figure 1 , Figure 2 and Figure 3 As shown, a photovoltaic-based, grid-powered flexible supplementary anti-backflow energy-saving power supply system includes a photovoltaic power generation component 1, the power output end of the photovoltaic power generation component 1 is connected to a photovoltaic / grid-powered DC grid-connected module 2, the photovoltaic / grid-powered DC grid-connected module 2 is also connected to a grid-powered voltage regulating and rectifying module 3, the grid-powered voltage regulating and rectifying module 3 is connected to the grid line of the State Grid, and the grid-powered voltage regulating and rectifying module 3 is connected to a power taking control switch KM1-1 on the power taking line, the power output side of the photovoltaic / grid-powered DC grid-connected module 2 is sequentially connected to a DC filter module 4, a sine wave inverter 5, and an AC filter and voltage stabilizing module 6, the AC filter and voltage stabilizing module 6 is connected to a load electrical appliance, and also includes a main controller for controlling the power supply mode and power safety, the main controller is respectively connected to the photovoltaic / grid-powered DC grid-connected module 2, the grid-powered voltage regulating and rectifying module 3, the power taking control switch KM1-1, the sine wave inverter 5, the AC filter and voltage stabilizing module 6 and the operating module HMI, and the operating module HMI is set as a touch screen.

[0040] This embodiment can control the reasonable configuration of the photovoltaic power generation component 1 and the grid power according to the power consumption of the load electrical appliances. Under sunny weather conditions, the photovoltaic power generation component 1 can obtain sufficient DC power, and through the cooperation of the photovoltaic / grid power DC grid-connected module 2, the DC filter module 4, the sine wave inverter 5, the AC filter voltage stabilizing module 6 and the AC filter voltage stabilizing module 6, the DC power generated by the photovoltaic power generation component 1 is inverted into AC power, and adjusted to the power parameters applicable to the load electrical appliances for the load electrical appliances to be used for operation; when the sunlight is weakened to the point where the power generation of the photovoltaic power generation component 1 is insufficient for the load electrical appliances to be consumed, it is automatically connected to the national grid under the control of the main controller, and the grid power voltage regulating and rectifying module 3 is used to take power, rectify and regulate the voltage, and the photovoltaic / grid power DC grid-connected module 2 is used to merge with the DC power of the photovoltaic power generation component 1, and the insufficient power is supplemented by the grid power to achieve flexible supplement of power, and then after the processes of inversion, filtering, voltage stabilization, etc., stable power is provided to the load electrical appliances.

[0041] In this embodiment, depending on the power consumption of the load electrical appliances, the photovoltaic power generation components 1 are provided with several groups, such as three groups, and are arranged in parallel. Several photovoltaic power generation panels are respectively provided in each photovoltaic power generation component 1. The photovoltaic power generation panels in the same group are sequentially arranged in series and then the stable output of direct current is achieved through photovoltaic bus voltage stabilization measures. Each photovoltaic power generation component 1 is respectively formed with a positive electrode of a power generation component and a negative electrode of a power generation component, which are used to achieve connection with the photovoltaic / grid power DC grid-connected module 2. The photovoltaic power generation components 1, photovoltaic bus voltage stabilization measures, etc. are all well known to ordinary technicians in this technical field and will not be described in detail here.

[0042] like Figure 2As shown, the photovoltaic / grid power DC grid-connected module 2 includes a positive bus and a negative bus, a plurality of positive terminals are arranged on the positive bus, a plurality of negative terminals are arranged on the negative bus, the positive poles of each of the power generation components are respectively connected to the corresponding positive terminals through wires, each of the wires is respectively connected in series with an isolation diode, the negative poles of each of the power generation components are respectively electrically connected to the corresponding negative terminals, the grid power voltage regulating rectifier module 3 is connected between one of the positive terminals and one of the negative terminals, and the positive bus and the negative bus are also respectively electrically connected to the input end of the DC filter module 4. When it is necessary to supplement power through grid electricity, the main controller controls the power-taking control switch KM1-1 to close, and the grid electricity voltage regulation and rectification module 3 can take power from the national grid, and after voltage regulation and rectification, it is transmitted to the photovoltaic / grid electricity DC grid-connected module 2, and merges with the DC power generated by the photovoltaic power generation component 1, and finally forms electric energy that can meet the work of the load electrical appliances with the cooperation of other subsequent modules. The power-taking control switch KM1-1 is generally set as the normally open contact of the relay, and the relay is connected to the main controller, so that the main controller can timely control the opening and closing of the power-taking control switch KM1-1, thereby realizing automatic switching on and off of grid electricity to ensure the safe and stable operation of the load electrical appliances.

[0043] like Figure 2 and Figure 3 As shown, the sine wave inverter 5 is provided with an inverter drive board and an inverter temperature controller M1, and the inverter drive board and the inverter temperature controller M1 are respectively connected to the main controller, and the main controller controls the sine wave inverter 5 through the inverter drive board to realize the inverter function. The main controller is set as a PLC controller. During the working process of the sine wave inverter 5, the inverter temperature controller M1 detects the temperature of the sine wave inverter 5 in real time, and transmits it to the main controller through the RS485 communication interface. The upper temperature limit value and the lower temperature limit value for temperature monitoring of the sine wave inverter 5 are preset in the main controller, so as to cooperate with the detection value of the inverter temperature controller M1 to realize the safe control of the working temperature of the sine wave inverter 5.

[0044] The sine wave inverter 5 is equipped with at least one cooling fan FJ for cooling, and the cooling fan FJ is connected to the main controller. Specifically, as in the present embodiment, three cooling fans FJ are equipped, and each cooling fan FJ is respectively provided with a fan relay for use, and the fan relay is connected to the control end of the main controller to realize the start and stop control of the cooling fan FJ by the main controller. When the inverter temperature controller M1 detects that the temperature of the sine wave inverter 5 reaches the upper temperature limit set by the main controller, the main controller controls the power supply of the corresponding cooling fan FJ through each fan relay, so that each cooling fan FJ starts to work to cool down the sine wave inverter 5; until the inverter temperature controller M1 detects that the temperature of the sine wave inverter 5 reaches the lower temperature limit set by the main controller, the main controller controls the power supply of the corresponding cooling fan FJ through each fan relay, so that each cooling fan FJ stops working to cool down the sine wave inverter 5, and realizes the automatic energy-saving operation of the temperature control of the sine wave inverter 5.

[0045] The power output end of the sine wave inverter 5 is connected to three inverter phase lines and one inverter neutral line. After the inverter processing of the sine wave inverter 5, it can output 50Hz AC power and filter and stabilize it by the AC filter voltage stabilization module 6. Specifically, the AC filter voltage stabilization module 6 includes AC filter inductors connected in series on each of the inverter phase lines, and AC filter capacitors connected between the inverter phase lines and the inverter neutral line connected to the power output end of the AC filter inductor. An output solid-state relay G1 is connected between the AC filter voltage stabilization module 6 and the load electrical appliance, and the output solid-state relay is connected to the main controller. Through the control of the output solid-state relay by the main controller, the electrical connection between the photovoltaic power generation component 1 and the load electrical appliance can be achieved, so as to automatically convert the power supply mode of the load electrical appliance in a timely manner, thereby achieving the purpose of intelligent and energy-saving electricity use.

[0046] The load electrical appliances of this embodiment are also connected to the grid line through three direct phase lines and one direct neutral line. The direct phase lines and the direct neutral lines are provided with isolation switches D, automatic reclosing switches-Q1 and bypass solid-state relays G1 in the direction of power supply, and the grid voltage regulating rectifier module 3 draws power from the line between the automatic reclosing switches-Q1 and the bypass solid-state relay G1. When the photovoltaic power generation assembly 1 needs maintenance due to a fault, or the power generation is seriously insufficient due to weather, time and other reasons, and it is difficult to maintain the operation of the load electrical appliances, the bypass solid-state relay G1 can be used to connect to the rest of the national power grid to achieve power from the grid to maintain operation. Various electrical components to ensure the safety of electricity use, such as fuses and other conventional supporting components, are also installed on the wires between the two. In order to simplify the view, they are not reflected in the figure.

[0047] In order to realize the safe monitoring of the power consumption system, in this embodiment, a grid power parameter acquisition module M2 for collecting grid power parameters is provided on the power intake side of the grid power voltage regulating and rectifying module 3, and an inverter parameter acquisition module M3 for collecting power supply parameters is provided on the power output side of the AC filtering and voltage stabilizing module 6, and the grid power parameter acquisition module M2 and the inverter parameter acquisition module M3 are respectively connected to the main controller. For example, the grid power parameter acquisition module M2 and the inverter parameter acquisition module M3 are set as active power meters, which can measure three-phase current, voltage, active and reactive power, electricity, harmonics, etc. The internal design combines modern microprocessor technology and AC sampling technology, has complete communication and networking functions, can be connected to the main controller, and can also be used online.

[0048] The power supply method of the anti-backflow energy-saving power supply system with photovoltaic as the main power supply and grid power as the flexible supplementary power supply method in this embodiment specifically includes photovoltaic power supply mode, grid power flexible supplementary power supply mode and grid power supply mode. When the power provided by the photovoltaic power generation component 1 can meet the working needs of the load electrical appliances, the system operates in the photovoltaic power supply mode; when the power supply of the photovoltaic power generation component 1 decreases or the amount of the load electrical appliances put into use increases, it is difficult to ensure the stable operation of the load electrical appliances by relying solely on the photovoltaic power generation component 1. At this time, it is necessary to start the grid power flexible supplementary power supply mode to supplement the power supply of the photovoltaic power generation component 1 according to the power shortage of the system; when the photovoltaic power generation component 1 cannot be used for some reason, the load electrical appliances are directly powered by the grid power supply mode. A power supply mode with photovoltaic as the main power supply and grid power as the auxiliary power supply is formed, which can make full use of photovoltaic power to the maximum extent and realize energy-saving operation of the power system. The specific implementation process of each mode is described as follows.

[0049] Photovoltaic power supply mode

[0050] The main controller obtains the power supply information of the photovoltaic power generation component 1, and at the same time, the main controller also obtains the power consumption information of the load electrical appliances, and processes and compares the power supply information with the power consumption information. The photovoltaic power generation component 1 includes photovoltaic panels, controllers, battery devices and other components used in conjunction with each other. The main controller can obtain the power supply information by connecting to the battery device. The connection control between the main controller and the load electrical appliances is realized through corresponding relays (such as K6-K9). The main controller can know the load electrical appliances that are started through the working status of the relays, and the rated working parameters of each load electrical appliance are calculated and processed to obtain the power consumption information.

[0051] In the comparison and judgment of the main controller, when the power supply information is greater than the power consumption information, it means that the photovoltaic power generation component 1 is sufficient to meet the power consumption of the load electrical appliances during operation, and the main controller controls the power control switch KM1-1 to remain in the disconnected state, even if the system is not connected to the national grid, and does not need to be supplemented by power from the grid. The electric energy generated by the photovoltaic power generation component 1 is converted into alternating current after passing through the photovoltaic / grid DC grid-connected module, the DC filter module 4, and the sine wave inverter 5, and is provided to the load electrical appliances after voltage stabilization by the AC filter voltage regulator module 6; when the power supply information is less than the power consumption information, it means that the photovoltaic power generation component 1 cannot meet the power consumption of the load electrical appliances during operation, and needs the support of the national grid, and the main controller controls the system to enter the grid flexible supplementary power supply mode.

[0052] Flexible supplementary power supply mode of grid electricity

[0053] The power shortage information is obtained by the main controller, and the main controller obtains the power shortage information by processing and calculating the power supply information and the power consumption information. When the power shortage information occurs, it is necessary to use the national grid for supplementary power consumption. The main controller controls the power control switch KM1-1 to close to realize the system taking power from the national grid.

[0054] After the power-taking control switch KM1-1 is closed to take power, the AC power of the grid line is converted into DC power through the grid voltage regulating and rectifying module 3, and sent to the photovoltaic / grid DC grid-connected module 2 to converge the DC power provided by the photovoltaic power generation component 1, and supplement the power shortage calculated by the main controller. Depending on the different amounts of load equipment put into use, the power shortage information is different when obtaining power support from the national grid, that is, under the control of the main controller, the power supplement is controllable and adjustable, thereby achieving flexible power replenishment.

[0055] In the process of flexible supplementary power supply from the grid, under the action of the isolation diodes and the grid voltage regulating and rectifying module 3 respectively connected in series on each of the said conductors, the DC power sent by the said photovoltaic power generation component 1 and the said grid voltage regulating and rectifying module 3 can only be converged in the said photovoltaic / grid DC grid-connected module 2 and enter the said DC filter module 4, and will not flow back to the said grid line to prevent excess electric energy from being sent into the grid. The anti-backflow protection of the said grid line is now provided to ensure the safe and stable operation of the national power system and solve the relevant technical defects in the anti-backflow of contact-type hard switching.

[0056] Grid power supply mode

[0057] The low power information of the photovoltaic power generation component 1 is preset in the main controller through the operation module HMI. When the main controller learns that the power supply information of the photovoltaic power generation component 1 is lower than the low power information, it means that the photovoltaic power generation component 1 is currently unavailable for power supply. The power taking control switch KM1-1 is then turned off, the bypass solid-state relay G1 is controlled to be closed, and the output solid-state relay G1 is controlled to be disconnected, so that the power grid line is used to directly power the load electrical appliances.

[0058] The present invention can also be applied to low-voltage three-phase and single-phase photovoltaic off-grid power generation systems that are not easy to connect to the grid, and to power supply to small factories, families, commercial hotels, restaurants, schools, nursing homes, hospitals, offices, etc. that use electricity for many electrical equipment. It can also be used to power special equipment such as photovoltaic energy-saving inverters, photovoltaic hot water projects, photovoltaic hot air drying and heating, photovoltaic heating and cooling air conditioners, photovoltaic refrigeration units, photovoltaic electromagnetic medium and high frequency furnaces, etc. It can fully utilize clean energy photovoltaic power generation, has the advantages of small investment, simple and flexible installation, obvious energy-saving effect, considerable economic benefits, etc., so it has a wide range of application scenarios and is easy to promote.

[0059] The description of the present invention is given for the purpose of illustration and description, and is not intended to be exhaustive or to limit the invention to the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for particular uses.

Claims

1. A photovoltaic-based, grid-powered flexible power supply system with anti-backflow energy saving, including a photovoltaic power generation component, characterized in that: The power output end of the photovoltaic power generation component is connected to a photovoltaic / grid power DC grid-connected module, and the photovoltaic / grid power DC grid-connected module is also connected to a grid power voltage regulating and rectifying module. The grid power voltage regulating and rectifying module is connected to the grid line of the State Grid, and the power taking line of the grid power voltage regulating and rectifying module is connected to a power taking control switch. The power output side of the photovoltaic / grid power DC grid-connected module is sequentially connected to a DC filter module, a sine wave inverter, and an AC filter voltage stabilizing module, and the AC filter voltage stabilizing module is connected to a load electrical appliance. It also includes a main controller for controlling the power supply mode and power safety, and the main controller is respectively connected to the photovoltaic / grid power DC grid-connected module, the grid power voltage regulating and rectifying module, the power taking control switch, the sine wave inverter, the AC filter voltage stabilizing module and the operation module.

2. The photovoltaic-based, grid-powered flexible power supply system for backflow prevention and energy saving as claimed in claim 1, characterized in that: The photovoltaic power generation components are provided in several groups and arranged in parallel, each photovoltaic power generation component is provided with several photovoltaic power generation panels, and each photovoltaic power generation panel in the same group is arranged in series in sequence and respectively forms a positive pole of the power generation component and a negative pole of the power generation component.

3. A photovoltaic-based, grid-powered flexible power supply system for backflow prevention and energy saving as claimed in claim 2, characterized in that: The photovoltaic / grid power DC grid-connected module includes a positive bus and a negative bus, a plurality of positive terminals are arranged on the positive bus, a plurality of negative terminals are arranged on the negative bus, the positive poles of each power generation component are respectively connected to the corresponding positive terminal through a wire, each wire is respectively connected in series with an isolation diode, the negative pole of each power generation component is respectively electrically connected to the corresponding negative terminal, the grid power voltage regulating rectifier module is connected between one of the positive terminals and one of the negative terminals, and the positive bus and the negative bus are also respectively electrically connected to the input end of the DC filter module.

4. The photovoltaic-based, grid-powered flexible power supply system of claim 1 is characterized by: The sine wave inverter is provided with an inverter drive board and an inverter temperature controller, the inverter drive board and the inverter temperature controller are respectively connected to the main controller, and the sine wave inverter is also equipped with at least one cooling fan for cooling, and the cooling fan is connected to the main controller.

5. The photovoltaic-based, grid-powered flexible power supply system for backflow prevention and energy saving as claimed in claim 1, characterized in that: The power output end of the sine wave inverter is connected to three inverter phase lines and one inverter neutral line. The AC filtering and voltage stabilizing module includes AC filtering inductors respectively connected in series with each of the inverter phase lines. The AC filtering capacitors respectively connected between the inverter phase line and the inverter neutral line corresponding to the power output end of the AC filtering inductor.

6. The photovoltaic-based, grid-powered flexible power supply system for anti-backflow energy saving as claimed in claim 3, characterized in that: An output solid-state relay is connected between the AC filtering and voltage stabilizing module and the load electrical appliance, and the output solid-state relay is connected to the main controller.

7. A photovoltaic-based, grid-powered flexible power supply system for backflow prevention and energy saving as claimed in claim 6, characterized in that: The load electrical appliances are connected to the power grid line through three direct-supply phase lines and one direct-supply neutral line, and isolation switches, automatic reclosing switches and bypass solid-state relays are sequentially provided on the direct-supply phase lines and the direct-supply neutral lines along the direction of power supply, and the grid power voltage regulating and rectifying module draws power from the line between the automatic reclosing switch and the bypass solid-state relay.

8. The photovoltaic-based, grid-powered flexible power supply system for anti-backflow energy saving as claimed in claim 7, characterized in that: A grid power parameter acquisition module for collecting grid power parameters is provided on the power intake side of the grid power voltage regulating and rectifying module, and an inverter parameter acquisition module for collecting power supply parameters is provided on the power output side of the AC filtering and voltage stabilizing module, and the grid power parameter acquisition module and the inverter parameter acquisition module are respectively connected to the main controller.

9. A power supply method for a photovoltaic-based, grid-powered flexible power supply system with anti-backflow energy-saving as claimed in claim 8, characterized in that: include, Photovoltaic power supply mode The main controller obtains the power supply information of the photovoltaic power generation component, and the main controller also obtains the power consumption information of the load electrical appliance, and processes and compares the power supply information with the power consumption information; When the power supply information is greater than the power consumption information, the main controller controls the power taking control switch to remain in an off state, and the electric energy generated by the photovoltaic power generation assembly is converted into alternating current after passing through the photovoltaic / grid power DC grid-connected module, the DC filter module, and the sine wave inverter, and is provided to the load electrical appliance after voltage stabilization processing by the AC filter voltage stabilization module; When the power supply information is less than the power consumption information, the main controller controls the system to enter a grid power flexible supplementary power supply mode; Flexible supplementary power supply mode of grid electricity The main controller calculates and obtains power shortage information, and controls the power taking control switch to close; The AC power of the grid line is converted into DC power through the grid power voltage regulating and rectifying module, and sent to the photovoltaic / grid power DC grid-connected module to converge the DC power provided by the photovoltaic power generation component, and the power shortage calculated by the main controller is supplemented. Under the action of the isolation diodes and the grid power voltage regulating and rectifying modules respectively connected in series on each of the wires, the DC power sent by the photovoltaic power generation component and the grid power voltage regulating and rectifying module can only be converged in the photovoltaic / grid power DC grid-connected module and enter the DC filtering module, and will not flow back to the grid line, thereby realizing anti-backflow protection for the grid line.

10. The power supply method according to claim 9, characterized in that: Also includes, Grid power supply mode The low power information of the photovoltaic power generation component is preset in the main controller through the operation module. When the main controller learns that the power supply information of the photovoltaic power generation component is lower than the low power information, the power supply control switch is in an off state, the bypass solid-state relay is controlled to be closed, and the output solid-state relay is controlled to be disconnected, so that the power grid line is used to directly power the load electrical appliances.

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