Grid-connected reverse power protection device

Abstract

The utility model provides a grid-connected reverse power protection device. The grid-connected reverse power protection device comprises a control unit, a plurality of photovoltaic modules, a plurality of inverters, a voltage and current acquisition unit, a power grid side and an electricity load, the control unit is respectively connected with the voltage and current acquisition unit and the inverter; the plurality of photovoltaic modules are connected with the plurality of inverters in a one-to-one correspondence manner, and the inverters are connected between the corresponding photovoltaic modules and the electricity loads; the voltage and current acquisition unit is connected between a power grid side and an electricity load. According to the embodiment of the invention, the output power of the inverter is adjusted through the control unit, so that the output power is adjusted in real time, self-generation and self-use can be met to the maximum extent on the premise that grid-connected reverse power is not generated, and waste of photovoltaic power generation resources is avoided.

Description

Technical Field

[0001] The present application relates to the field of distributed photovoltaic power generation new energy technology, and in particular to a grid-connected reverse power protection device. Background Art

[0002] The distributed photovoltaic grid-connected power supply system is connected to the public power grid distribution system at the same time. Due to special requirements for load change control, the power supply department needs to ensure the quality and reliability of power supply to users. At the same time, the operation of the distributed photovoltaic grid-connected power supply system cannot affect the safety of the distribution system. Therefore, at present, when the quota of distributed photovoltaic power generation exceeds a certain proportion, the distributed photovoltaic power source is not allowed to reverse power to the power system, that is, the phenomenon of grid-connected reverse power is not allowed.

[0003] However, in order to solve the problem of grid-connected reverse power in the prior art, a common method is to set a main circuit breaker on the photovoltaic side and the grid side, and solve the problem of grid-connected reverse power by controlling the opening and closing of the main circuit breaker. For example, when the phenomenon of grid-connected reverse power occurs, the main switch of the main circuit breaker is turned off, resulting in the photovoltaic power generation system being unable to supply power to users. This method is too simple and crude and will cause a waste of photovoltaic power generation resources. Utility Model Content

[0004] The present application provides a grid-connected reverse power protection device to solve the problems existing in the above-mentioned background technology.

[0005] The present application provides a grid-connected reverse power protection device, comprising:

[0006] Control unit, multiple photovoltaic modules, multiple inverters, voltage and current acquisition unit, grid side, power load;

[0007] The control unit is connected to the voltage and current acquisition unit and the inverter respectively;

[0008] The plurality of photovoltaic components are connected to the plurality of inverters in a one-to-one correspondence, and the inverter is connected between the corresponding photovoltaic component and the power load;

[0009] The voltage and current acquisition unit is connected between the power grid side and the power load.

[0010] Optionally, the grid-connected reverse power protection device further includes a control main switch, one end of the control main switch is connected to the grid side, and the other end of the control main switch is connected to the multiple inverters.

[0011] Optionally, the grid-connected reverse power protection device further includes a human-computer interaction device, and the human-computer interaction device is connected to the control unit.

[0012] Optionally, the grid-connected reverse power protection device also includes a switch state detection unit and a switch state control unit; the switch state detection unit and the switch state control unit are both connected to the control main switch, and the switch state detection unit and the switch state control unit are both connected to the control unit.

[0013] Optionally, the grid-connected reverse power protection device further includes a grid-connected switch, the grid-connected switch is connected between the grid side and the power load, and the grid-connected switch is connected to the control unit;

[0014] The voltage and current acquisition unit is connected between the grid-connected switch and the power load.

[0015] Optionally, the control unit is connected to the voltage and current acquisition unit and the inverter via a communication line.

[0016] Optionally, the voltage and current acquisition unit includes: a current transformer and a voltage transformer;

[0017] The current transformer and the voltage transformer are connected to the control unit.

[0018] Optionally, it also includes: a terminal device;

[0019] The terminal device is connected to the control unit.

[0020] In this embodiment, the grid-connected reverse power protection device includes: a control unit, multiple photovoltaic modules, multiple inverters, a voltage and current acquisition unit, a grid side, and a power load; the control unit is connected to the voltage and current acquisition unit and the inverter respectively; multiple photovoltaic modules are connected to multiple inverters in a one-to-one correspondence, and the inverter is connected between the corresponding photovoltaic modules and the power load; the voltage and current acquisition unit is connected between the grid side and the power load. Compared with the prior art, the present application sets a control unit and a voltage and current acquisition unit. When a grid-connected reverse power problem occurs, the output power of the inverter is adjusted by the control unit, thereby adjusting the output power in real time, so that under the premise of not generating grid-connected reverse power, it can meet the self-generation and self-use to the greatest extent, avoiding the waste of photovoltaic power generation resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1A schematic diagram of the structure of a grid-connected reverse power protection device provided in one embodiment of the present application;

[0023] Figure 2 A schematic diagram of the structure of a grid-connected reverse power protection device provided in another embodiment of the present application;

[0024] Figure 3 A logical schematic diagram of a grid-connected reverse power protection device provided in one embodiment of the present application.

[0025] In the figure: 1-control unit; 2-photovoltaic module; 3-inverter; 4-voltage and current acquisition unit; 5-grid side; 6-power load; 7-control main switch; 8-human-machine interaction device; 9-switch state detection unit; 10-switch state control unit; 11-grid-connected switch; 12-terminal equipment. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present application.

[0027] Figure 1 A grid-connected reverse power protection device is shown according to an embodiment of the present application. Figure 1 As shown, it includes: a control unit 1, multiple photovoltaic modules 2, multiple inverters 3, a voltage and current acquisition unit 4, a grid side 5, and an electrical load 6;

[0028] The control unit 1 is connected to the voltage and current acquisition unit 4 and the inverter 3 respectively;

[0029] A plurality of photovoltaic modules 2 are connected to a plurality of inverters 3 in a one-to-one correspondence, and the inverters 3 are connected between the corresponding photovoltaic modules 2 and the electrical loads 6;

[0030] The voltage and current acquisition unit 4 is connected between the grid side 5 and the electrical load 6 .

[0031] Among them, the control unit 1 can be, for example, a micro control unit 1 (Micro Control Unit, MCU), and the control unit 1 is connected to the voltage and current acquisition unit 4, and is used to receive the voltage and current between the current grid side 5 and the power load 6 detected by the voltage and current acquisition unit 4, and calculate the power corresponding to the current voltage and current, wherein the voltage and current between the current grid side 5 and the power load 6 detected by the voltage and current acquisition unit 4 include a value and a direction. When the voltage and current are detected to be positive values, it means that the grid side 5 provides electrical energy to the power load 6, and the corresponding power is positive power, that is, the power described below; when the voltage and current are detected to be negative values, it means that the power generation power of the photovoltaic component 2 is greater than the power required by the power load 6. At this time, the excess electrical energy flows to the grid side 5, and the corresponding power is reverse power.

[0032] The control unit 1 is connected to the inverters 3 and is used to obtain the current output power of each inverter 3 and control the output power of each inverter 3 .

[0033] When the control unit 1 adjusts the output power of the inverter 3 , the output power of all the inverters 3 is adjusted at the same time, so that the output power of all the inverters 3 changes at the same time.

[0034] Among them, the photovoltaic component 2 is used to provide the electricity required by the electrical load 6. The photovoltaic component 2 is generally set under the sun. When light shines on the metal of the photovoltaic component 2, the energy of the light is completely absorbed by the electrons in the metal. When the energy absorbed by the electrons is large enough, they can overcome the internal gravity of the metal to do work, leave the metal surface and escape, thus becoming photoelectrons, that is, the photovoltaic component 2 generates electrical energy.

[0035] The inverter 3 is connected between the power load 6 and the photovoltaic assembly 2 , and is used to convert the direct current generated by the photovoltaic assembly 2 into alternating current, and provide the corresponding electric energy generated by the photovoltaic assembly 2 to the power load 6 .

[0036] In addition, the number of photovoltaic modules 2 is set according to the needs of the work site, and the number of inverters 3 is set according to the number of photovoltaic modules 2 .

[0037] The use process of the above-mentioned grid-connected reverse power protection device is as follows:

[0038] During the operation of the photovoltaic module 2, the grid side 5 and the power load 6, the voltage and current acquisition unit 4 monitors the current current and voltage between the grid side 5 and the power load 6 in real time, and uploads the results to the control unit 1 in real time. The control unit 1 calculates the power corresponding to the current voltage and current, and determines whether there is a reverse power situation at present.

[0039] When the control unit 1 determines that there is a reverse power situation, the control unit 1 detects whether the time when the reverse power situation occurs exceeds the preset time. When the reverse power exceeds the preset time, the output power of the inverter 3 needs to be reduced. At this time, after the control unit 1 obtains the current output power of all inverters 3, the control unit 1 determines whether the current output power of the inverter 3 is the minimum output power of the inverter 3. If not, the control unit 1 sends a control instruction to adjust the output power to each inverter 3 according to the magnitude of the reverse power. The inverter 3 lowers the output power according to the received control instruction, so that the output power of all inverters 3 is equal to or less than the power required by the electrical load 6, solving the reverse power problem; if so, the inverter 3 is controlled to stop providing power to the electrical load 6.

[0040] When the control unit 1 determines that a reverse power situation exists, the control unit 1 detects whether the time when the reverse power situation occurs exceeds a preset time. When the reverse power situation does not exceed the preset time, the control unit 1 obtains the current output power of the inverter 3 and the power required for consumption at the power load 6, and adjusts the output power of the inverter 3 so that the grid-connected photovoltaic components 2 and the grid side 5 jointly provide electrical energy to the user load.

[0041] Among them, it should be noted that the power provided by the grid side 5 should be appropriate. For example, the power provided by the grid side 5 is greater than 10% of the power provided by the photovoltaic component 2. In this way, when the power required by the power load 6 is reduced, the reverse power problem will not easily occur. In addition, the power provided by the grid side 5 should generally not be too much, otherwise, the user's electricity cost will increase, resulting in a waste of electricity generated by the photovoltaic component 2.

[0042] When the control unit 1 determines that the power consumption between the grid side 5 and the power load 6 exceeds the predetermined range, it is necessary to increase the power provided by the photovoltaic assembly 2 to the power load 6. After the control unit 1 obtains the current output power of each inverter 3, if it is determined that the current output power is not the maximum output power of the inverter 3, the control unit 1 sends a control instruction to increase the output power to all inverters 3, thereby adjusting the output power of the inverter 3.

[0043] When the output power of the inverter 3 is increased or decreased, the control unit 1 determines the range of increasing or decreasing the output power of the inverter 3 according to the extent to which the current reverse power or power consumption exceeds the preset range.

[0044] In this embodiment, the grid-connected reverse power protection device includes: a control unit 1, multiple photovoltaic modules 2, multiple inverters 3, a voltage and current acquisition unit 4, a grid side 5, and an electrical load 6; the control unit 1 is connected to the voltage and current acquisition unit 4 and the inverter 3 respectively; multiple photovoltaic modules 2 are connected to multiple inverters 3 in a one-to-one correspondence, and the inverter 3 is connected between the corresponding photovoltaic modules 2 and the electrical load 6; the voltage and current acquisition unit 4 is connected between the grid side 5 and the electrical load 6. Compared with the prior art, the present application sets a control unit 1 and a voltage and current acquisition unit 4. When a grid-connected reverse power problem occurs, the output power of the inverter 3 is adjusted by the control unit 1, thereby adjusting the output power in real time, so that under the premise of not generating grid-connected reverse power, it can meet the self-generation and self-use to the greatest extent, avoiding the waste of photovoltaic power generation resources.

[0045] Alternatively, see Figure 2 The grid-connected reverse power protection device also includes a control main switch 7, one end of the control main switch 7 is connected to the grid side 5, and the other end of the control main switch 7 is connected to the multiple inverters 3.

[0046] Among them, the control main switch 7 is in a normally closed state. When the control unit 1 detects the presence of a reverse power situation, the inverter 3 sends the current output power to the control unit 1. When all inverters 3 are at the minimum output power and the reverse power situation occurs for more than a preset time, the control unit 1 sends a control instruction to the control main switch 7, and the control main switch 7 is disconnected, thereby alleviating the reverse power situation.

[0047] When the main control switch 7 is in the off state, if the power demand of the power load 6 increases, causing the control unit 1 to detect that the power consumption exceeds the set range, at this time, the inverter 3 is required to provide power to the power load 6, so the main control switch 7 needs to be controlled to be closed again.

[0048] At this time, first, since the output power of all inverters 3 is the minimum value, the control unit 1 adjusts the output power of the inverter 3 according to the power consumption, so that the inverter 3 provides electric energy to the power load 6, for example, the power provided by the inverter 3 to the power load 6 is 80% of the power required by the power load 6, thereby reducing the power consumption of the grid side 5. Then, the control main switch 7 is closed again. The opening and closing of the control main switch 7 can be completed manually.

[0049] In addition, in actual working process, there is rarely a situation where the main control switch 7 needs to be disconnected.

[0050] Alternatively, see Figure 3 The grid-connected reverse power protection device also includes a human-machine interaction device 8 , which is connected to the control unit 1 .

[0051] Among them, the human-machine interaction device 8 is a display screen and a keyboard, a touch screen, etc., wherein, when the human-machine interaction device 8 is a display screen and a keyboard, the display screen and the keyboard are connected, and are both connected to the control unit 1. The control unit 1 uploads the received current voltage and current, the power corresponding to the current voltage and current, the switch state of the control main switch 7 and other information to the display screen of the human-machine interaction device 8 for display, so that the staff can intuitively understand the power supply situation of the current power load 6. The keyboard is used to input data such as preset time and preset range into the control unit 1. For example, the preset time is 1s, and the preset range is that the power consumption is 90% of the photovoltaic power generation power, and it is displayed on the display screen for the convenience of the staff to operate.

[0052] When the human-machine interaction device 8 is a touch screen, the touch screen integrates the functions of a display screen and buttons, which will not be described in detail here.

[0053] Alternatively, see Figure 2 , the grid-connected reverse power protection device further includes a grid-connected switch 11, the grid-connected switch 11 is connected between the grid side 5 and the power load 6, and the grid-connected switch 11 is connected to the control unit 1;

[0054] The voltage and current acquisition unit 4 is connected between the grid-connected switch 11 and the electrical load 6 .

[0055] The grid-connected switch 11 is a normally closed switch. In actual operation, the grid-connected switch 11 is generally not disconnected. When the device fails and needs to be stopped, the control unit 1 controls the grid-connected switch 11 to close to prevent the grid side 5 from continuing to supply power.

[0056] Alternatively, see Figure 3 The grid-connected reverse power protection device also includes a switch state detection unit 9 and a switch state control unit 10; the switch state detection unit 9 and the switch state control unit 10 are both connected to the control main switch 7, and the switch state detection unit 9 and the switch state control unit 10 are both connected to the control unit 1.

[0057] The control unit 1 is connected to the switch state detection unit 9 and is used to obtain the switch state of the current control main switch 7 detected by the switch state detection unit 9 .

[0058] The control unit 1 is connected to the switch state control unit 10 and is used to control the on and off of the main switch 7 through the switch state control unit 10 .

[0059] Furthermore, when it is necessary to disconnect the control main switch 7, for example, when a reverse power situation occurs and the control unit 1 detects that the reverse power situation exceeds a preset time, the control unit 1 obtains through the switch state detection unit 9 that the current control main switch 7 is in a closed state, and the control unit 1 sends a control instruction to the switch state control unit 10, and the switch state control unit 10 controls the control main switch 7 to disconnect.

[0060] When it is necessary to close the control main switch 7, the control unit 1 obtains the information that the current control main switch 7 is in the open state through the switch state detection unit 9. The control unit 1 first adjusts the output power of the inverter 3 according to the power consumption, so that the inverter 3 can provide electrical energy to the power load 6. For example, the power provided by the inverter 3 to the power load 6 is 80% of the power required by the power load 6, thereby reducing the power consumption on the grid side 5. Then, a control instruction is sent to the switch state control unit 10, and the switch state control unit 10 controls the control main switch 7 to close.

[0061] Among them, the switch state detection unit 9 can be a voltage sensor or a current sensor. When the switch state detection unit 9 is a voltage sensor, when the voltage in the voltage sensor detection circuit is greater than the first preset voltage value, the main switch 7 is controlled to be in a closed state, and the switch state detection unit 9 transmits the detection result to the control unit 1. When the voltage in the voltage sensor detection circuit is less than the second preset voltage value, the main switch 7 is controlled to be in an open state, and the switch state detection unit 9 transmits the detection result to the control unit 1. Furthermore, the first preset voltage value is greater than the second preset voltage value.

[0062] When the switch state detection unit 9 is a current sensor, when the current in the current sensor detection circuit is greater than the first preset current value, the main switch 7 is controlled to be in a closed state, and the switch state detection unit 9 transmits the detection result to the control unit 1. When the current in the current sensor detection circuit is less than the second preset current value, the main switch 7 is controlled to be in an open state, and the switch state detection unit 9 transmits the detection result to the control unit 1. Furthermore, the first preset current value is greater than the second preset current value.

[0063] Among them, the switch state control unit 10 includes an optocoupler switch and a relay. The control main switch 7 can be, for example, a circuit breaker. The optocoupler switch is connected to the control unit. When the optocoupler switch receives an opening control instruction or a closing control instruction sent by the control unit, the optocoupler switch opens or closes accordingly according to the control instruction. When the optocoupler switch is opened, the coil of the relay is energized so that the contacts of the relay are opened. When the contacts of the relay are opened, the circuit breaker is opened, that is, the control main switch 7 is opened. When the optocoupler switch is closed, the coil of the relay is energized so that the contacts of the relay are closed. When the contacts of the relay are closed, the circuit breaker is closed, that is, the control main switch 7 is closed.

[0064] Optionally, the control unit 1 is connected to the voltage and current acquisition unit 4 and the inverter 3 via a communication line.

[0065] Among them, the communication circuit is an RS485 communication cable, which is used to connect the control unit 1 with the voltage and current acquisition unit 4 and the inverter 3, improve the signal transmission rate between the control unit 1 and other units, and prevent other electromagnetic interference from causing transmission signal errors.

[0066] Optionally, the voltage and current acquisition unit 4 includes: a current transformer and a voltage transformer;

[0067] The current transformer and the voltage transformer are connected to the control unit 1 .

[0068] Among them, the current transformer is used to detect the direction of the current between the current grid side 5 and the power load 6, and detect the magnitude of the current. When the direction of the current is from the grid side 5 to the power load 6, the current is positive, and when the direction of the current is from the photovoltaic component 2 to the grid side 5, the current is negative.

[0069] Among them, the voltage transformer is used to detect the direction of the current voltage between the grid side 5 and the power load 6, and to detect the magnitude of the current voltage. When the direction of the voltage is from the grid side 5 to the power load 6, the voltage is a positive number, and when the direction of the voltage is from the photovoltaic module 2 to the grid side 5, the voltage is a negative number.

[0070] Alternatively, see Figure 3 The grid-connected reverse power protection device also includes: a terminal device 12, and the terminal device 12 is connected to the control unit 1.

[0071] Among them, the terminal device 12 is connected to the control unit 1 through 4G / 5G, Bluetooth, etc., and is used to remotely control the control unit 1 to adjust the output power and other data of the inverter 3, and monitor the current inverter 3 output power, the power consumption of the grid side 5, the power consumption of the power load 6, etc. in real time, and can set preset time, preset range, etc., so that the staff can remotely control it, which is more convenient for the staff to monitor the working status of the device.

[0072] The terminal device 12 may be a mobile phone, a laptop computer or other device.

[0073] Finally, it should be noted that all contents not described in the technical solution of this application can be implemented using existing technologies. In addition, the above embodiments are only used to illustrate the technical solution of this application, rather than to limit it; although the application is described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above embodiments, or replace some or all of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A grid-connected reverse power protection device, characterized in that: include: Control unit, multiple photovoltaic modules, multiple inverters, voltage and current acquisition unit, grid side, power load; The control unit is connected to the voltage and current acquisition unit and the inverter respectively; The plurality of photovoltaic components are connected to the plurality of inverters in a one-to-one correspondence, and the inverter is connected between the corresponding photovoltaic component and the power load; The voltage and current acquisition unit is connected between the power grid side and the power load.

2. The grid-connected reverse power protection device according to claim 1, characterized in that: It also includes a control main switch, one end of which is connected to the grid side, and the other end of which is connected to the multiple inverters.

3. The grid-connected reverse power protection device according to claim 1, characterized in that: It also includes a human-computer interaction device, which is connected to the control unit.

4. The grid-connected reverse power protection device according to claim 2, characterized in that: It also includes a switch state detection unit and a switch state control unit; the switch state detection unit and the switch state control unit are both connected to the control main switch, and the switch state detection unit and the switch state control unit are both connected to the control unit.

5. The grid-connected reverse power protection device according to claim 1, characterized in that: It also includes a grid-connected switch, which is connected between the grid side and the power load, and the grid-connected switch is connected to the control unit; The voltage and current acquisition unit is connected between the grid-connected switch and the power load.

6. The grid-connected reverse power protection device according to claim 2, characterized in that: The control unit is connected to the voltage and current acquisition unit and the inverter via a communication line.

7. The grid-connected reverse power protection device according to any one of claims 1 to 6, characterized in that: The voltage and current acquisition unit includes: a current transformer and a voltage transformer; The current transformer and the voltage transformer are connected to the control unit.

8. The grid-connected reverse power protection device according to any one of claims 1 to 6, characterized in that: Also includes: Terminal equipment; The terminal device is connected to the control unit.

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