Grid-connected control circuit, power distribution equipment and power grid system

Abstract

The invention relates to a grid-connected control circuit, power distribution equipment and a power grid system. The grid-connected control circuit comprises a voltage detection module, a processing module and a grid-connected control module. The voltage detection module is used for being connected with a power grid, detecting the voltage of the power grid and outputting power grid voltage parameters. The processing module is connected with the voltage detection module and used for receiving the power grid voltage parameter and outputting a disconnection signal when determining that the voltage of the power grid is abnormal according to the power grid voltage parameter; the grid-connected control module is connected with the processing module and the photovoltaic access device, and the photovoltaic access device is used for connecting electric energy output by the photovoltaic power generation system into a power grid; and the grid-connected control module is used for stopping connecting the electric energy output by the photovoltaic power generation system into the power grid when receiving the disconnection signal. Therefore, the voltage state of the power grid (such as commercial power) is monitored in real time, the connection between the photovoltaic power generation system and the power grid can be automatically disconnected when the abnormal voltage of the power grid is detected, the safety of the photovoltaic power generation system and the power grid is protected, the efficiency is higher, and the timeliness is better.

Description

Technical Field

[0001] The present application relates to the technical field of power transmission, and in particular to a grid-connected control circuit, power distribution equipment and a power grid system. Background Art

[0002] Photovoltaic power grid connection is the process of converting the direct current generated by solar panels into alternating current that meets the requirements of the power grid (such as the municipal power grid) through a grid-connected inverter and directly connecting it to the grid. At present, the mainstream trend in the field of photovoltaic power generation is decentralized small-scale grid-connected photovoltaic systems, especially building integrated photovoltaic (BIPV) systems. Such systems have been widely promoted and applied due to their low investment cost, fast construction speed, and small footprint. From coastal areas to inland areas, a large number of decentralized small-scale grid-connected photovoltaic networks have been established in various places.

[0003] However, with the rapid increase in the number of these small-scale grid-connected photovoltaics, their grid-connected management also faces many challenges. First, the manual management method has low management efficiency and poor timeliness, and it is difficult to meet the needs of rapid response and efficient management. Secondly, the management method that relies heavily on manual labor has also led to a significant increase in management and operating costs, increasing the overall burden on the system.

[0004] Therefore, how to optimize the grid-connected management of photovoltaic power generation is an urgent problem to be solved. Summary of the invention

[0005] Based on this, it is necessary to provide a grid-connected control circuit, power distribution equipment and power grid system to reduce the reliance on manual labor in grid-connected management.

[0006] A grid-connected control circuit, comprising:

[0007] A voltage detection module is used to connect to a power grid, detect the voltage of the power grid, and output power grid voltage parameters;

[0008] a processing module connected to the voltage detection module, configured to receive the grid voltage parameter, and output a disconnection signal when determining that the grid voltage is abnormal according to the grid voltage parameter;

[0009] A grid-connected control module is connected to the processing module and the photovoltaic access device, wherein the photovoltaic access device is used to connect the electric energy output by the photovoltaic power generation system into the power grid; the grid-connected control module is used to control the photovoltaic access device to stop connecting the electric energy output by the photovoltaic power generation system into the power grid when receiving the disconnection signal.

[0010] In one embodiment, the voltage detection module includes a sampling circuit and a signal conditioning circuit, the sampling circuit is used to connect to the power grid, and the signal conditioning circuit is respectively connected to the sampling circuit and the processing module;

[0011] The sampling circuit is used to detect the voltage of the power grid to output a sampled voltage signal;

[0012] The signal conditioning circuit is used to receive the sampled voltage signal, process the sampled voltage signal and then output the grid voltage parameter.

[0013] In one of the embodiments, the sampling circuit includes a current limiting resistor and a voltage transformer, the input side of the voltage transformer is connected to the power grid through the current limiting resistor, and the output side of the voltage transformer is connected to the signal conditioning circuit.

[0014] In one of the embodiments, the signal conditioning circuit includes an operational amplifier circuit and a clamping circuit;

[0015] The input end of the operational amplifier circuit is connected to the output side of the voltage transformer, the output end of the operational amplifier circuit is connected to the clamping circuit, and the common end of the operational amplifier circuit and the clamping circuit is connected to the processing module.

[0016] In one embodiment, the clamping circuit includes a first clamping diode and a second clamping diode, the cathode of the first clamping diode and the anode of the second clamping diode are both connected to the output end of the operational amplifier circuit, and the output end of the operational amplifier circuit is also connected to the processing module; the anode of the first clamping diode is grounded, and the cathode of the second clamping diode is connected to a first power supply.

[0017] In one embodiment, the grid-connected control module includes a control switch and a relay; the controlled end of the control switch is connected to the processing module, the first end of the control switch is connected to the first end of the coil of the relay, and the second end of the control switch is grounded; the second end of the coil of the relay is connected to a second power supply, and the contacts of the relay are connected to the photovoltaic access device.

[0018] In one embodiment, the control switch includes a switch tube and a first resistor, the controlled end of the switch tube is connected to the processing module via the first resistor, the first end of the switch tube is connected to the first end of the coil of the relay, and the second end of the switch tube is grounded.

[0019] In one embodiment, the grid-connected control circuit further includes a power supply module, the input side of the power supply module is used to connect to the photovoltaic power generation system, and the output side of the power supply module is respectively connected to the processing module and the grid-connected control module;

[0020] The power supply module is used to convert the electric energy provided by the photovoltaic power generation system and output the power supply voltage to the processing module and the grid-connected control module.

[0021] A power distribution device comprises a photovoltaic access device and the above-mentioned grid-connected control circuit.

[0022] A power grid system comprises a photovoltaic power generation system, a power grid and the power distribution equipment described above.

[0023] The above-mentioned grid-connected control circuit, power distribution equipment and power grid system include a voltage detection module, a processing module and a grid-connected control module. The voltage detection module is used to connect to the power grid, detect the voltage of the power grid, and output the power grid voltage parameters; the processing module is connected to the voltage detection module, and is used to receive the power grid voltage parameters, and output a disconnection signal when the power grid voltage is determined to be abnormal according to the power grid voltage parameters; the grid-connected control module is connected to the processing module and the photovoltaic access device, and the photovoltaic access device is used to connect the electric energy output by the photovoltaic power generation system to the power grid; the grid-connected control module is used to control the photovoltaic access device to stop connecting the electric energy output by the photovoltaic power generation system to the power grid when receiving the disconnection signal. In this way, the voltage state of the power grid (such as the mains) is monitored in real time, and the connection between the photovoltaic power generation system and the power grid can be automatically disconnected when the power grid voltage is detected to protect the safety of the photovoltaic power generation system and the power grid. As a result, it is no longer necessary to rely on manual management of photovoltaic grid connection, and compared with manual management methods, automatic control is more efficient and more timely, and can save a lot of labor costs and reduce the operating cost of the entire photovoltaic network. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] FIG1 is a schematic diagram of a module of a grid-connected control circuit according to an embodiment;

[0026] FIG2 is a schematic diagram of a module of a grid-connected control circuit according to another embodiment;

[0027] FIG3 is a schematic diagram of a circuit structure of a voltage detection module according to an embodiment;

[0028] FIG4 is a schematic diagram of a circuit structure of a grid-connected control module according to an embodiment;

[0029] FIG5 is a schematic diagram of a circuit structure of a processing module according to an embodiment;

[0030] FIG6 is a module schematic diagram of a grid-connected control circuit according to another embodiment;

[0031] FIG7 is a schematic diagram of a circuit structure of a power supply module according to an embodiment;

[0032] FIG8 is a schematic diagram of a circuit structure of a power supply module according to another embodiment;

[0033] FIG9 is a schematic diagram of a circuit structure of a power supply module according to another embodiment;

[0034] FIG. 10 is a schematic diagram of a module of a power distribution device according to an embodiment. DETAILED DESCRIPTION

[0035] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0037] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0038] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0039] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least a portion of an element” means a part or all of an element.

[0040] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0041] In one embodiment, a grid-connected control circuit is provided. As shown in FIG1 , the grid-connected control circuit of one embodiment includes a voltage detection module 100, a processing module 200, and a grid-connected control module 300. The voltage detection module 100 is used to connect to the power grid, the processing module 200 is respectively connected to the voltage detection module 100 and the grid-connected control module 300, and the grid-connected control module 300 is also used to connect to a photovoltaic access device. The photovoltaic access device is used to connect the electric energy output by the photovoltaic power generation system to the power grid.

[0042] The voltage detection module 100 is used to detect the voltage of the power grid and output the power grid voltage parameters. The processing module 200 is used to receive the power grid voltage parameters and output a disconnection signal when it is determined that the power grid voltage is abnormal according to the power grid voltage parameters. The grid connection control module 300 is used to control the photovoltaic access device to stop connecting the power output of the photovoltaic power generation system to the power grid when receiving the disconnection signal.

[0043] It can be understood that the photovoltaic power generation system includes solar panels and grid-connected inverters. The solar panels absorb sunlight energy and convert it into DC power. The grid-connected inverter is responsible for converting the DC power generated by the solar panels into AC power with the same frequency and phase as the power grid. The AC power converted by the grid-connected inverter is connected to the power grid through the grid-connected interface module. The power grid can be a public power grid, such as a city power grid.

[0044] The photovoltaic access device includes a grid-connected interface module, one end of which is used to connect to a grid-connected inverter, and the other end is used to connect to a public power grid. In actual implementation, the photovoltaic access device can be set in a power distribution device such as a power distribution cabinet or a power distribution box. The processing module 200 can control the photovoltaic access device to connect the electric energy output by the photovoltaic power generation system to the power grid, or stop connecting the electric energy output by the photovoltaic power generation system to the power grid through the grid-connected control module 300.

[0045] Specifically, the voltage detection module 100 is connected to the power grid line, obtains the voltage signal of the power grid, and converts it into a processable power grid voltage parameter, thereby being able to monitor the voltage of the power grid in real time and provide accurate power grid voltage data for the subsequent processing module 200.

[0046] The processing module 200 receives the grid voltage parameters from the voltage detection module 100, and determines whether the grid voltage is normal according to a preset voltage range or an abnormal threshold. When it is detected that the grid voltage exceeds the preset voltage range or reaches the preset abnormal threshold, the processing module 200 will immediately output a disconnect signal. In some embodiments, when the grid voltage parameter is lower than the preset abnormal threshold, it is determined that the grid voltage has dropped sharply, and a disconnect signal is output at this time. In other embodiments, when the grid voltage parameter is higher than the preset abnormal threshold, it is determined that the grid voltage has risen sharply, and a disconnect signal is output at this time. In other embodiments, when the grid voltage parameter exceeds the preset voltage range, it is determined that the grid voltage fluctuates abnormally, and a disconnect signal is output at this time. Among them, the preset voltage range or preset abnormal threshold of the grid needs to be set in combination with actual conditions.

[0047] The disconnection signal is an instruction for controlling the photovoltaic access device to disconnect from the power grid. When the grid-connected control module 300 receives the disconnection signal from the processing module 200, the grid-connected control module 300 will quickly control the photovoltaic access device to cut off the connection between the photovoltaic power generation system and the power grid, preventing the photovoltaic power generation system from continuing to supply power to the power grid. This can prevent the photovoltaic power generation system from causing impact or damage to the power grid when the power grid voltage is abnormal.

[0048] It can be understood that in actual implementation, when the processing module 200 determines that the grid voltage has returned to normal based on the grid voltage parameters transmitted by the voltage detection module 100, it can also output a grid-connected signal to the grid-connected control module 300, so as to control the photovoltaic access device through the grid-connected control module 300, so that the photovoltaic power generation system can resume supplying power to the grid, thereby realizing comprehensive control of photovoltaic grid connection.

[0049] The above-mentioned grid-connected control circuit can monitor the voltage status of the power grid in real time, and can automatically disconnect the photovoltaic power generation system from the power grid when detecting abnormal grid voltage, thereby realizing automatic control of photovoltaic grid connection and protecting the safety of the photovoltaic power generation system and the power grid. Therefore, it is no longer necessary to rely on manual management of photovoltaic grid connection, and compared with manual management, automatic control is more efficient and more timely, and can save a lot of labor costs and reduce the operating costs of the entire photovoltaic network.

[0050] In one embodiment, as shown in FIG. 2 , the voltage detection module 100 includes a sampling circuit 110 and a signal conditioning circuit 120 ; the sampling circuit 110 is used to connect to a power grid, and the signal conditioning circuit 120 is respectively connected to the sampling circuit 110 and the processing module 200 .

[0051] The sampling circuit 110 is used to detect the voltage of the power grid to output a sampled voltage signal. The signal conditioning circuit 120 is used to receive the sampled voltage signal, process the sampled voltage signal, and output the power grid voltage parameter to the processing module 200.

[0052] Specifically, the sampling circuit 110 reduces the high voltage of the power grid to a low voltage range suitable for subsequent circuit processing, and the signal conditioning circuit 120 receives the sampled voltage signal from the sampling circuit 110 and performs corresponding processing, such as amplification, filtering, linearization, etc., to convert it into a power grid voltage parameter that can be identified and processed by the processing module 200. The amplitude, waveform and phase of the power grid voltage parameter processed by the signal conditioning circuit 120 are more suitable for subsequent digital processing, so that the processing module 200 can more accurately judge the state of the power grid voltage and make corresponding control decisions. As a result, the voltage detection module 100 can realize accurate detection and conversion of the power grid voltage, and provide reliable data support for the control decision of the subsequent processing module 200.

[0053] In one embodiment, as shown in FIG. 3 , the sampling circuit 110 may include a current limiting resistor R1 and a voltage transformer T1 , the input side of the voltage transformer T1 is connected to the grid through the current limiting resistor R1 , and the output side of the voltage transformer T1 is connected to the signal conditioning circuit 120 .

[0054] It can be understood that the connector P1 in the embodiment shown in FIG. 3 is used to connect to the power grid, wherein pin 1 of the connector P1 is connected to the ground wire, pin 2 is used to connect to the neutral wire of the power grid, and pin 3 is used to connect to the live wire of the power grid.

[0055] The grid voltage connected to the input side (primary) of the voltage transformer T1 is converted into current after passing through the current limiting resistor R1. After the current passes through the voltage transformer T1, the output side (secondary) outputs a low voltage signal, i.e., a sampled voltage signal, thereby achieving safe and accurate sampling of the grid voltage. The sampled voltage signal will be used as the input of the signal conditioning circuit 120 for further amplification, filtering, linearization and other processing.

[0056] The voltage transformer T1 generally has high insulation strength and precise voltage conversion ratio, which can ensure that the output voltage signal accurately reflects the true value of the grid voltage. The voltage transformer T1 can be selected according to specific circumstances. Optionally, the voltage transformer T1 is a precision current type voltage transformer HPT205A.

[0057] The resistance value of the current limiting resistor R1 needs to be set according to the specific situation, for example, according to the rated value of the grid voltage, the rated current of the voltage transformer T1 and the safety requirements of the system. The current limiting resistor R1 can be an independent resistor or an equivalent circuit composed of multiple electrical components (such as resistors). The main function of the current limiting resistor R1 is to limit the current passing through the voltage transformer T1 to prevent abnormal current from being generated when the grid voltage is abnormal (such as short circuit, lightning strike, etc.), thereby protecting the voltage transformer T1 and other subsequent circuits from damage.

[0058] In one embodiment, the signal conditioning circuit 120 may include an operational amplifier circuit 121 and a clamping circuit 122; the input end of the operational amplifier circuit 121 is connected to the output side of the voltage transformer T1, the output end of the operational amplifier circuit 121 is connected to the clamping circuit 122, and the common end of the operational amplifier circuit 121 and the clamping circuit 122 is connected to the processing module 200 for outputting the grid voltage parameters.

[0059] In the signal conditioning circuit 120 of this embodiment, the operational amplifier circuit 121 and the clamping circuit 122 work together to further process the sampled voltage signal from the voltage transformer T1 so as to convert it into a grid voltage parameter suitable for processing by the processing module 200 .

[0060] Specifically, the operational amplifier circuit 121 is capable of receiving the sampled voltage signal from the voltage transformer T1, and performing amplification and bias adjustment. Amplification enables the sampled voltage signal to be enhanced to a sufficient amplitude so that the subsequent circuit can more easily process and identify it. Bias adjustment is used to ensure that the DC component (i.e., bias voltage) of the output signal is at an appropriate level, which helps to improve the stability and reliability of the signal.

[0061] The clamp circuit 122 receives the output signal from the operational amplifier circuit 121 and limits the voltage range within the predetermined upper and lower limits to prevent the processing module 200 from being damaged or generating erroneous results due to receiving an overly high or underlying voltage signal. Through the processing of the clamp circuit 122, it can be ensured that the grid voltage parameters received by the processing module 200 always operate within a safe voltage range, thereby improving the safety and reliability of the entire circuit. Among them, the predetermined upper and lower limits need to be set in combination with actual conditions.

[0062] In this embodiment, the operational amplifier circuit 121 and the clamping circuit 122 cooperate with each other in the signal conditioning circuit to jointly complete the processing processes such as amplification, bias adjustment, and voltage range limitation of the sampled voltage signal. These processes not only improve the stability and reliability of the signal, but also protect the safety of the subsequent circuits and improve the reliability of the grid voltage parameters. Finally, these processed voltage parameters are passed to the processing module 200, providing it with more accurate and reliable input data, thereby ensuring the accuracy and reliability of the control decision.

[0063] The circuit structure of the operational amplifier circuit 121 and the clamping circuit 122 can be set according to actual conditions. In one embodiment, the operational amplifier circuit 121 includes an operational amplifier U12, a resistor R2, a resistor R3, a resistor R31, a resistor R32, an inductor L5, an inductor L6, a capacitor C3, a capacitor C60, a capacitor C61, a capacitor C62 and a capacitor C63. The positive input terminal (pin 3 in the figure) and the negative input terminal (pin 2 in the figure) of the operational amplifier U12 are respectively connected to the two ends of the output side of the voltage transformer T1; the positive input terminal is connected to the output terminal (pin 6 in the figure) through the resistor R2 and the resistor R3 in turn; the capacitor C3 is connected between the positive input terminal and the output terminal. The resistor R31 is connected between the two bias balance terminals (pin 1 and pin 8 in the figure) of the operational amplifier U12, and the resistor R32 is connected between the resistor R31 and the first power supply voltage VDD1. The power supply terminal (pin 7 in the figure) of the operational amplifier U12 is connected to the first power supply voltage VDD1 through the inductor L5. The first ends of capacitors C60 and C61 are connected to the power supply terminal of operational amplifier U12, and the second ends of capacitors C60 and C61 are grounded. The ground terminal of operational amplifier U12 (pin 4 in the figure) is connected to the second power supply voltage VSS via inductor L6, and the first ends of capacitors C62 and C63 are connected to the ground terminal of operational amplifier U12, and the second ends of capacitors C62 and C63 are grounded. The magnitudes of the first power supply voltage VDD1 and the second power supply voltage VSS need to be set in accordance with actual conditions. Optionally, the model of operational amplifier U12 is OP07CDR, and correspondingly, the first power supply voltage VDD1 is +15V, and the second power supply voltage VSS is -15V.

[0064] In one embodiment, the clamping circuit 122 includes a first clamping diode D5 and a second clamping diode D6, the cathode of the first clamping diode D5 and the anode of the second clamping diode D6 are both connected to the output end of the operational amplifier circuit 121, and the output end of the operational amplifier circuit 121 is also connected to the processing module 200; the anode of the first clamping diode D5 is grounded, and the cathode of the second clamping diode D6 is connected to the first power supply VDD2.

[0065] Thus, the first clamping diode D5 and the second clamping diode D6 form a bidirectional clamping circuit. When the output voltage of the operational amplifier circuit 121 drops below the ground potential (i.e., 0V), the first clamping diode D5 will be turned on to clamp the output voltage at the ground potential to prevent it from further decreasing. When the output voltage of the operational amplifier circuit 121 rises to a voltage exceeding the voltage of the first power supply VDD2, the second clamping diode D6 will be turned on to clamp the output voltage at the potential of VDD2 to prevent it from further increasing. Thus, the grid voltage parameter finally output to the processing module 200 will not be too high or too low, so as to protect the subsequent processing module 200.

[0066] The size of the first power supply VDD2 can be determined according to actual conditions. For example, when the processing module 200 includes a 3.3V MCU (Microcontroller Unit), the first power supply VDD2 can be 3.3V. In actual implementation, the signal conditioning circuit 120 can also include a resistor R33, a first end of the resistor R33 is connected to the output end of the operational amplifier U12, and a second end of the resistor R33 is used to output the grid voltage parameter. The resistance value of the resistor R33 can be set according to actual conditions, for example, it can be 0 ohms, which is reserved for circuit testing and debugging.

[0067] In one embodiment, as shown in FIG4 , the grid-connected control module 300 may include a control switch 310 and a relay RYL1; the controlled end of the control switch 310 is connected to the processing module 200, the first end of the control switch 310 is connected to the first end of the coil of the relay RYL1 (shown as interface 1), and the second end of the control switch 310 is grounded; the second end of the coil of the relay RYL1 (shown as interface 4) is connected to the second power supply VDD3, and the contacts of the relay RYL1 are connected to the photovoltaic access device.

[0068] When the processing module 200 determines that the voltage of the grid is abnormal according to the grid voltage parameter and outputs a disconnection signal to the control switch 310, the control switch 310 is closed, and the coil of the relay RYL1 is energized (powered by the second power supply VDD3), and the contact state of the relay RYL1 changes accordingly, thereby controlling the connection between the photovoltaic access device and the grid to be disconnected, and stopping the electric energy output by the photovoltaic power generation system from being connected to the grid. In this way, the connection state between the photovoltaic access device and the grid can be flexibly controlled to ensure the safety of photovoltaic grid connection.

[0069] Furthermore, when the processing module 200 determines that the grid voltage has returned to normal based on the grid voltage parameters, it can also output a grid-connected signal to the control switch 310. At this time, the control switch 310 is disconnected, the coil of the relay RYL1 is de-energized, and the contact state of the relay RYL1 is switched, thereby controlling the connection between the photovoltaic access device and the grid, so that the photovoltaic power generation system resumes supplying power to the grid.

[0070] In the embodiment shown in FIG4 , one end of the contact of the relay RYL1 is used to connect to the grid-connected inverter, and the other end is used to connect to the grid-connected interface. When the coil of the relay RYL1 is energized, its contact is disconnected. In actual implementation, the two ends of the contact of the relay RYL1 can be respectively connected to the two ends of the low-voltage control switch P3. The low-voltage control switch P3 is a low-voltage control switch of the power switch of the power distribution equipment (such as the power distribution cabinet). The function of the power switch of the power distribution cabinet is the input and output of high-power AC power.

[0071] Furthermore, the grid-connected control module 300 may further include a freewheeling diode D4 , wherein an anode of the freewheeling diode D4 is connected to a first end of the coil of the relay RYL1 , and a cathode of the freewheeling diode D4 is connected to a second end of the coil of the relay RYL1 .

[0072] When the coil of relay RYL1 is energized, a magnetic field is generated around it. When the coil is suddenly de-energized, due to the principle of electromagnetic induction, the magnetic field in the coil will quickly disappear and a reverse electromotive force will be generated at both ends of the coil. This reverse electromotive force may damage other sensitive components in the circuit (such as the switch tube in the control switch 310). By connecting a freewheeling diode D4 in parallel at both ends of the relay coil, when the power is off, the freewheeling diode D4 will be turned on, providing a release path for the reverse electromotive force, thereby eliminating or weakening this reverse electromotive force to protect the circuit.

[0073] The grid-connected control module 300 may further include a capacitor C64 and a capacitor C65, wherein the first ends of the capacitors C64 and C65 are connected to the second end of the coil of the relay RYL1, and the second ends of the capacitors C64 and C65 are grounded. The size of the second power supply VDD3 may be set according to actual conditions, and illustratively, the second power supply VDD3 may be 5V.

[0074] In one embodiment, the control switch 310 includes a switch tube Q1 and a first resistor R34, the controlled end of the switch tube Q1 is connected to the processing module 200 via the first resistor R34, the first end of the switch tube Q1 is connected to the first end of the coil of the relay RYL1, and the second end of the switch tube Q1 is grounded.

[0075] Specifically, when the processing module 200 outputs a disconnection signal to the first resistor R34, the signal reaches the controlled end of the switch tube Q1 after passing through the first resistor R34, turning on the switch tube Q1. At this time, the current can flow from the second power supply VDD3 through the switch tube Q1 into the coil of the relay RYL1, disconnecting the contacts of the relay RYL1. When the processing module 200 outputs a grid-connected signal to the switch tube Q1, the switch tube Q1 will be turned off, the coil of the relay RYL1 will lose current, and the contacts will return to their original state.

[0076] In this embodiment, the on-off of the switch tube Q1 is controlled to control the coil current of the relay RYL1, and then the contact state of the relay RYL1 is controlled, so that fast and accurate switching action can be achieved.

[0077] The type of the switch tube Q1 can be set according to the specific situation, for example, it can be a MOS (Metal-Oxide-Semiconductor) tube or a triode, and the controlled end, the first end, and the second end of the switch tube Q1 need to be defined according to its type. Optionally, the switch tube Q1 is an NMOS (such as 2N7002K), the gate of which is the controlled end, the source is the first end, and the drain is the second end.

[0078] In one embodiment, as shown in FIG5 , the processing module 200 includes an MCU chip U10 and its external circuit, and the specific model of the MCU chip U10 can be selected according to the specific situation. The external circuit includes a reset circuit composed of a resistor R21, a capacitor C35 and a button REST1; a first crystal oscillator circuit composed of a capacitor C36, a capacitor C37, and a crystal oscillator X1; a second crystal oscillator circuit composed of a capacitor C38, a capacitor C39 and a crystal oscillator X4; and a debugging circuit composed of a connector U9. The power pin of the MCU chip U10 uses a two-capacitor combination filter circuit, and its pin VBAT is respectively connected to the first end of the capacitor C40, the first end of the capacitor C41 and the first power supply VDD2, and the second ends of the capacitor C40 and the capacitor C41 are both grounded. The pin VDD_1 of the MCU chip U10 is respectively connected to the first end of the capacitor C44, the first end of the capacitor C45 and the first power supply VDD2, and the second end of the capacitor C44 and the second end of the capacitor C45 are both grounded. The pin VDD_3 of the MCU chip U10 is respectively connected to the first end of the capacitor C46, ​​the first end of the capacitor C47 and the first power supply VDD2, and the second end of the capacitor C46 and the second end of the capacitor C47 are both grounded. The pin VDD_2 of the MCU chip U10 is respectively connected to the first end of the capacitor C48, the first end of the capacitor C49 and the first power supply VDD2, and the second end of the capacitor C48 and the second end of the capacitor C49 are both grounded.

[0079] A magnetic bead and a capacitor are added to the analog power pin of the MCU chip U10 to form an LC filter circuit. Specifically, the pin VDD_A of the MCU chip U10 is connected to the first end of the capacitor C42, the first end of the capacitor C43 and the first end of the magnetic bead L2, the second end of the magnetic bead L2 is connected to the first power supply VDD2, and the second end of the capacitor C42 and the second end of the capacitor C43 are both grounded.

[0080] In one embodiment, as shown in FIG. 6 , the grid-connected control circuit further includes a power supply module 400 , the input side of the power supply module 400 is used to connect to the photovoltaic power generation system, and the output side of the power supply module 400 is respectively connected to the processing module 200 and the grid-connected control module 300 .

[0081] The power supply module 400 is used to convert the electric energy provided by the photovoltaic power generation system and output the power supply voltage to the processing module 200 and the grid-connected control module 300 .

[0082] The input side of the power supply module 400 is directly connected to the photovoltaic power generation system, and converts the original electric energy provided by the photovoltaic power generation system to output a power supply voltage adapted to the processing module 200 and the grid-connected control module 300, thereby eliminating the need for external power supply.

[0083] It can be understood that when the power supply voltages required by the processing module 200 and the grid-connected control module 300 are different, the output side of the power supply processing module 400 may include a first output terminal and a second output terminal, the first output terminal is used to provide the processing module 200 with a power supply voltage adapted to the processing module 200, and the second output terminal is used to provide the grid-connected control module 300 with a power supply voltage adapted to the grid-connected control module 300.

[0084] In one embodiment, as shown in FIG7 , the power supply processing module 400 may include an AC-DC (alternating current-direct current) conversion chip U5, whose input side is used to connect to the photovoltaic power generation system to access the high-voltage alternating current converted by the grid-connected inverter. In the embodiment shown in FIG7 , the input side of the AC-DC conversion chip U5 is connected to the connector P2, and the connector P2 can be connected to the grid-connected inverter in the photovoltaic power generation system, or can be connected to the grid-connected interface. The AC-DC conversion chip U5 is used to convert high-voltage alternating current into low-voltage direct current. In some embodiments, the AC-DC conversion chip U5 may be an ATS15-5-W chip, and the pin L of the chip is connected to the connector P2 through the fuse element F1 (such as a fuse), and the pin N of the chip is connected to the connector P2. The pin VO+ of the chip is connected to the first end of the resistor R37, the cathode of the voltage regulator tube TV1, and the first end of the capacitor C4; the pin VO- of the chip is connected to the anode of the voltage regulator tube TV1, and the second end of the capacitor C4; the second end of the resistor R37 is used to output the second power supply VDD3. The capacitor C2 is connected between the second end of the resistor R37 and the ground. Optionally, the second power supply VDD3 may be 5V.

[0085] In some embodiments, the adaptation voltage of the MCU chip U10 is a first power supply VDD2 lower than the second power supply VDD3, such as 3.3V. Correspondingly, as shown in FIG8 , the power supply processing module 400 may also include an LDO (Low Dropout Regulator) chip U11, and the pin VIN of the LDO chip U11 is used to access the second power supply VDD3. A resistor R30 is connected between the pin CE and the pin VIN of the LDO chip U11, and the first end of the resistor R29 is connected to the pin CE, and the second end is grounded. The pin VOUT of the LDO chip U11 is used to output the first power supply VDD2. In actual implementation, capacitors C5 and C6 may be set between the pin VIN and the ground, and capacitors C7 and C8 may be set between the pin VOUT and the ground. Further, the power supply processing module 400 may also include a resistor R4 and a light emitting diode LED1, the anode of the light emitting diode LED1 is connected to the pin VOUT of the LDO chip U11 through the resistor R4, and the cathode is grounded. Optionally, the model of the LDO chip U11 may be XC6210BMR.

[0086] In some embodiments, the adaptation voltage of the operational amplifier U12 is a first power supply voltage VDD1 of +15V and a second power supply voltage VSS of -15V. Correspondingly, as shown in FIG9 , the power supply processing module 400 may also include a DC-DC conversion chip U4 and an external circuit. Optionally, the DC-DC conversion chip U4 may be a dual-output DC-DC converter TPS65130RGET. Specifically, the pin INP of the DC-DC conversion chip U4 is connected to the first end of the inductor L3, and the second end of the inductor L3 is connected to the first end of the capacitor C57, the first end of the capacitor C58, the first end of the capacitor C59, the pin INN, the first end of the resistor R26, the first end of the resistor R27, and the second power supply VDD3 through the transistor Q2. The gate of the transistor Q2 is connected to the pin BSW; the second end of the capacitor C57, the second end of the capacitor C58, and the second end of the capacitor C59 are all grounded. The second end of the resistor R26 is connected to the pin VIN, the pin ENP, and the pin ENN, respectively. The second end of the resistor R27 is connected to the first end of the resistor R28, the pin PSP and the pin PSN respectively, and the second end of the resistor R28 is grounded. The pin INP is also connected to the pin VPOS, the first end of the resistor R22, the first end of the capacitor C50, the first end of the resistor R35, and the first end of the capacitor C51 through the diode D2. The second end of the capacitor C51 is grounded, and the second end of the resistor R35 is used to output the first supply voltage VDD1 of +15V. The second ends of the resistor R22 and the capacitor C50 are both connected to the pin FBP and the first end of the resistor R23, and the second end of the resistor R23 is grounded. Pin VREF is connected to the first end of resistor R24 ​​and the first end of capacitor C52 respectively, and the second end of capacitor C52 is grounded; the second end of resistor R24 ​​is connected to pin FBN, the first end of resistor R25 and the first end of capacitor C53 respectively, pin VNEG is connected to the second end of resistor R25, the second end of capacitor C53, the first end of resistor R36, the first end of capacitor C54, and the anode of diode D3 respectively, and the second end of resistor R36 is used to output the second power supply voltage VSS of -15V. The second end of capacitor C54 is grounded, and the cathode of diode D3 is connected to the first end of inductor L4 and pin OUTN respectively. Pin CP is connected to the first end of capacitor C55, pin CN is connected to the first end of capacitor C56, and the second end of capacitor C55, the second end of capacitor C56, pin PP, pin AGND and pin PGND are all grounded. Thus, dual power supply output of +15V and -15V is achieved.

[0087] In order to better understand the above embodiment, a detailed explanation is given below in conjunction with a specific embodiment. In one embodiment, the grid-connected control circuit includes a voltage detection module 100, a processing module 200, a grid-connected control module 300 and a power supply module 400, the power supply module 400 can be set with reference to Figures 7-9, the processing module 200 can be set with reference to Figure 5, the grid-connected control module 300 can be set with reference to Figure 3, and the voltage detection module 100 can be set with reference to Figure 3.

[0088] The connector P2 of the power supply module 400 is used to connect to the main power supply from the photovoltaic grid, and then output a 5V DC power supply, namely the second power supply VDD3, after being processed by the AC-DC conversion chip U5 (such as ATS15-5-W). One second power supply VDD3 is converted into the 3.3V first power supply VDD2 by the LDO chip U11 (such as XC6210BMR) and then supplies power to the MCU chip U10 in the processing module 200. Another second power supply VDD3 outputs ±15V after passing through the DC-DC conversion chip U4 (such as TPS65130RGET), and supplies power to the operational amplifier U12 in the voltage detection module 100.

[0089] Specifically, the primary side of the voltage transformer T1 (such as HPT205A) in the voltage detection module 100 is connected to the mains power grid through a current limiting resistor R1, and the mains power grid voltage is converted into current. The secondary side outputs the current signal after passing through the voltage transformer T1, and is converted into the required grid voltage parameter through the operational amplifier U12.

[0090] The grid voltage parameters collected from the mains are input from the PB0 pin of the MCU chip U10 (i.e., the AD acquisition port). After internal logic processing, the pin PA6 of the MCU chip U10 will output a control signal (JD signal) to the NMOS tube Q1 to achieve on / off control of the mains and the photovoltaic grid. The MCU chip U10 gives the NMOS tube Q1 a high-level control signal (i.e., a disconnection signal), and the NMOS tube Q1 is turned on, causing the contact of RLY1 to disconnect, thereby controlling the mains and the photovoltaic grid to disconnect; the MCU chip U10 gives the NMOS tube Q1 a low-level control signal (i.e., a grid-connected signal), and the NMOS tube Q1 is disconnected, causing the contact of RLY1 to resume connection, thereby controlling the mains and the photovoltaic grid to connect, so as to continue to be connected to the grid.

[0091] The above-mentioned grid-connected control circuit can realize automatic disconnection and grid-connection of the photovoltaic network according to whether the mains power is abnormal, with high efficiency and good timeliness. It can also save a lot of labor costs and reduce the operating cost of the entire photovoltaic network.

[0092] In one embodiment, a power distribution device is provided, as shown in Fig. 10, including a photovoltaic access device 10 and a grid-connected control circuit 20. The grid-connected control circuit 20 can be configured with reference to the above embodiments, which will not be described in detail herein.

[0093] In one embodiment, a power grid system is provided, including a photovoltaic power generation system, a power grid and a power distribution device. The power distribution device can be configured with reference to the above embodiment, and will not be described in detail.

[0094] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0095] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A grid-connected control circuit, characterized in that: include: A voltage detection module is used to connect to a power grid, detect the voltage of the power grid, and output power grid voltage parameters; a processing module connected to the voltage detection module, configured to receive the grid voltage parameter, and output a disconnection signal when determining that the grid voltage is abnormal according to the grid voltage parameter; A grid-connected control module is connected to the processing module and the photovoltaic access device, wherein the photovoltaic access device is used to connect the electric energy output by the photovoltaic power generation system into the power grid; the grid-connected control module is used to control the photovoltaic access device to stop connecting the electric energy output by the photovoltaic power generation system into the power grid when receiving the disconnection signal.

2. The grid-connected control circuit according to claim 1, characterized in that: The voltage detection module includes a sampling circuit and a signal conditioning circuit, the sampling circuit is used to connect to the power grid, and the signal conditioning circuit is respectively connected to the sampling circuit and the processing module; The sampling circuit is used to detect the voltage of the power grid to output a sampled voltage signal; The signal conditioning circuit is used to receive the sampled voltage signal, process the sampled voltage signal and then output the grid voltage parameter.

3. The grid-connected control circuit according to claim 2, characterized in that: The sampling circuit comprises a current limiting resistor and a voltage transformer. The input side of the voltage transformer is connected to the power grid through the current limiting resistor, and the output side of the voltage transformer is connected to the signal conditioning circuit.

4. The grid-connected control circuit according to claim 3, characterized in that: The signal conditioning circuit includes an operational amplifier circuit and a clamping circuit; The input end of the operational amplifier circuit is connected to the output side of the voltage transformer, the output end of the operational amplifier circuit is connected to the clamping circuit, and the common end of the operational amplifier circuit and the clamping circuit is connected to the processing module.

5. The grid-connected control circuit according to claim 4, characterized in that: The clamping circuit includes a first clamping diode and a second clamping diode, wherein the cathode of the first clamping diode and the anode of the second clamping diode are both connected to the output end of the operational amplifier circuit, and the output end of the operational amplifier circuit is also connected to the processing module; the anode of the first clamping diode is grounded, and the cathode of the second clamping diode is connected to the first power supply.

6. The grid-connected control circuit according to claim 1, characterized in that: The grid-connected control module includes a control switch and a relay; the controlled end of the control switch is connected to the processing module, the first end of the control switch is connected to the first end of the coil of the relay, and the second end of the control switch is grounded; the second end of the coil of the relay is connected to a second power supply, and the contacts of the relay are connected to the photovoltaic access device.

7. The grid-connected control circuit according to claim 6, characterized in that: The control switch includes a switch tube and a first resistor, the controlled end of the switch tube is connected to the processing module via the first resistor, the first end of the switch tube is connected to the first end of the coil of the relay, and the second end of the switch tube is grounded.

8. The grid-connected control circuit according to any one of claims 1 to 7, characterized in that: It also includes a power supply module, the input side of the power supply module is used to connect to the photovoltaic power generation system, and the output side of the power supply module is respectively connected to the processing module and the grid-connected control module; The power supply module is used to convert the electric energy provided by the photovoltaic power generation system and output the power supply voltage to the processing module and the grid-connected control module.

9. A power distribution device, characterized in that: It comprises a photovoltaic access device and a grid-connected control circuit according to any one of claims 1 to 8.

10. A power grid system, characterized in that: It comprises a photovoltaic power generation system, a power grid and the power distribution equipment according to claim 9.

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