Distributed photovoltaic grid-connected control circuit

Abstract

A distributed photovoltaic grid-connected control circuit disclosed by the present invention comprises a main control unit and a sub-detection unit, the main control unit comprises a plurality of triodes, a plurality of resistors, an operational amplifier, a diode, a capacitor and a solid-state relay, a base electrode of a triode Q1 in the plurality of triodes is connected with an LO end, and an emitting electrode is connected with one end of a coil of a solid-state relay K1; the base electrode of the triode Q3 is connected with the base electrode of the triode Q4, one end of the solid-state relay K1 and one end of the resistor R5, the collector electrode is connected with one end of the resistor R7, and the emitter electrode is connected with the anode and IN end of the diode D6; the collector of the triode Q4 is connected with the inverting end of the operational amplifier U5, one end of the capacitor C2 and one end of the resistor R14; the base electrode of the triode Q5 is connected with the cathode of the diode D6 and one end of the resistor R13, the emitter electrode is connected with one end of the resistor R3 and one end of the resistor R4, and the collector electrode is connected with the base electrode of the triode Q6; the collector of the triode Q6 is connected with one end of the capacitor C1, the other end of the resistor R7 and the VO end; and the other end of the solid-state relay K1, the collector of the triode Q1, the emitter of the triode Q4 and the other end of the resistor R3 are connected with a power supply.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic grid-connected technology, and in particular to a distributed photovoltaic grid-connected control circuit. Background Art

[0002] When the photovoltaic grid-connected system performs phase switching, it is necessary to detect the three-phase parameters of the power grid in real time as a basis for switching. However, in actual operation, the instantaneous voltage fluctuations generated during the grid connection process are too large, which will cause delays in parameter detection, and may cause the system to perform incorrect phase grid-connected operations based on the delayed detection results. In addition, with the expansion of the scale of distributed photovoltaic units and the increase in power differences between different systems, when new photovoltaic units are connected, in order to avoid the impact current caused by the simultaneous grid connection of multiple systems, it is often necessary to configure an additional independent control system to achieve time-sharing grid connection. This will increase the complexity of the operation and bring many inconveniences to operation and maintenance, significantly reducing the overall management efficiency of the photovoltaic grid-connected system. Summary of the Invention

[0003] In view of the above technical problems, the purpose of the present invention is to provide a distributed photovoltaic grid-connected control circuit, including a main control unit and a sub-detection unit, wherein the main control unit includes a plurality of transistors, a plurality of resistors, an operational amplifier, a diode, a capacitor, and a solid-state relay. The base of the transistor Q1 among the plurality of transistors is connected to the LO terminal, and the emitter is connected to one end of the coil of the solid-state relay K1; the base of the transistor Q3 is connected to the base of the transistor Q4, one end of the solid-state relay K1, and one end of the resistor R5, the collector is connected to one end of the resistor R7, and the emitter is connected to the anode and IN terminal of the diode D6; the collector of the transistor Q4 is connected to the inverting terminal of the operational amplifier U5, one end of the capacitor C2, and one end of the resistor R14; the base of the transistor Q5 is connected to the cathode of the diode D6 and one end of the resistor R13, the emitter is connected to one end of the resistor R3, one end of the resistor R4, and the collector is connected to the base of the transistor Q6; the collector of the transistor Q6 is connected to one end of the capacitor C1, the other end of the resistor R7, and the VO terminal; the other end of the solid-state relay K1, the transistor The collector of Q1, the emitter of transistor Q4, and the other end of resistor R3 are connected to the power supply; the other end of the coil of solid-state relay K1, the emitter of transistor Q6, the other end of resistor R4, the other end of resistor R5, the other end of resistor R13, the other end of resistor R14, the other end of capacitor C1, and the other end of capacitor C2 are grounded; the sub-detection unit includes several diodes, triggers, operational amplifiers, AND gates, and field-effect transistors. The first pin of the trigger U1 is connected to the power supply, the second pin is connected to the sixth pin and the anode of diode D1, the third pin is connected to the cathode of diode D5, the fourth pin is connected to the cathode of diode D1, and the fifth pin is connected to the gate of field-effect transistor Q2; the in-phase terminal of operational amplifier U2 is connected to the VO terminal, the inverting terminal is connected to the Pi terminal, and the output terminal is connected to the source and Si terminal of field-effect transistor Q2; the first input terminal of AND gate U3 is connected to the output terminal of operational amplifier U5, the second input terminal is connected to the drain of field-effect transistor Q2 and the anode of diode D3, and the output terminal is connected to the anode of diode D5; the cathode of diode D3 is connected to the LO terminal.

[0004] Furthermore, it also includes a switching unit, and the main control unit also includes several resistors, several diodes, an operational amplifier, an AND gate, and a counter. The operational amplifier U6 is connected to one end of the capacitor C2 in phase, and the output end is connected to the first input end of the AND gate U7; the second input end of the AND gate U7 is connected to the fifth pin of the trigger U1, and the output end is connected to the anode of the diode D2 and the anode of the diode D4; one end of the resistor R1 is connected to the Pi end; one end of the resistor R2 is connected to the cathode of the diode D1 and the cathode of the diode D2; the cathode of the diode D4 is connected to the cathode of the diode D5; the third pin of the counter U4 is connected to the Vi end, the eleventh pin is connected to the fifteenth pin, the fourteenth pin is connected to the anode of the diode D5, and the sixteenth pin is connected to the power supply; the other end of the resistor R1, the other end of the resistor R2, and the eighth pin of the counter U4 are grounded; the switching unit includes a solid-state relay and a resistor, one end of the resistor R16 is connected to the power supply, and the other end is connected to one end of the solid-state relay K2; the other end of the solid-state relay K2 is connected to the Pi end, one end of the coil is connected to the Vi end, and the other end of the coil is grounded.

[0005] Furthermore, the number of the sub-detection units is consistent with the number of photovoltaic grid-connected control units.

[0006] Furthermore, the number of the switch units is consistent with the number of photovoltaic grid-connected control units.

[0007] Furthermore, the main control unit also includes several resistors, one end of the resistor R9 among the several resistors is connected to one end of the resistor R8 and the non-inverting end of the operational amplifier U5, and the other end is connected to one end of the resistor R10 and the inverting end of the operational amplifier U6; the other end of the resistor R10 is connected to the power supply; and the other end of the resistor R8 is grounded.

[0008] Furthermore, the sub-detection unit further includes a resistor, one end of the resistor R6 is connected to the gate of the field effect transistor Q2, and the other end is grounded.

[0009] Furthermore, the main control unit also includes several resistors, one end of the resistor R11 among the several resistors is connected to the third pin of the trigger U1; one end of the resistor R12 is connected to the thirteenth pin of the counter U4; one end of the resistor R15 is connected to the fifteenth pin of the counter U4; the other end of the resistor R11, the other end of the resistor R12, and the other end of the resistor R15 are grounded.

[0010] Furthermore, the capacitor C1 and the capacitor C2 are adjustable capacitors.

[0011] The beneficial effects of the present invention compared with the prior art are:

[0012] The present invention can perform weight grading during the control process, which is beneficial to the grid connection of newly added photovoltaic units, and generates an adjustable interruption period when each level of photovoltaic units is connected to the grid, providing a detection time window for judging the phase or disconnection of the second-level photovoltaic grid connection and resetting the main control unit for multiplexing. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, a brief introduction is given below to the prior art and the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 This is a circuit structure diagram of the main control unit and sub-detection unit provided by the present invention.

[0015] Figure 2 This is a circuit structure diagram of the switch unit provided by the present invention. DETAILED DESCRIPTION

[0016] In order to make the objects and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the embodiments. It should be understood that the following text is only used to describe one or several specific implementation methods of the present invention and does not strictly limit the scope of protection specifically requested by the present invention.

[0017] The present invention discloses a distributed photovoltaic grid-connected control circuit, including a main control unit and a sub-detection unit. The main control unit includes a plurality of transistors, a plurality of resistors, an operational amplifier, a diode, a capacitor, and a solid-state relay. The base of the transistor Q1 among the plurality of transistors is connected to the LO terminal, and the emitter is connected to one end of the coil of the solid-state relay K1; the base of the transistor Q3 is connected to the base of the transistor Q4, one end of the solid-state relay K1, and one end of the resistor R5, the collector is connected to one end of the resistor R7, and the emitter is connected to the anode and IN terminal of the diode D6; the collector of the transistor Q4 is connected to the inverting terminal of the operational amplifier U5, one end of the capacitor C2, and one end of the resistor R14; the base of the transistor Q5 is connected to the cathode of the diode D6 and one end of the resistor R13, the emitter is connected to one end of the resistor R3, one end of the resistor R4, and the collector is connected to the base of the transistor Q6; the collector of the transistor Q6 is connected to one end of the capacitor C1, the other end of the resistor R7, and the VO terminal; the other end of the solid-state relay K1, the collector of the transistor Q1, The emitter of transistor Q4 and the other end of resistor R3 are connected to the power supply; the other end of the coil of solid-state relay K1, the emitter of transistor Q6, the other end of resistor R4, the other end of resistor R5, the other end of resistor R13, the other end of resistor R14, the other end of capacitor C1, and the other end of capacitor C2 are grounded; the sub-detection unit includes several diodes, triggers, operational amplifiers, AND gates, and field-effect transistors. The first pin of the trigger U1 is connected to the power supply, the second pin is connected to the sixth pin and the anode of diode D1, the third pin is connected to the cathode of diode D5, the fourth pin is connected to the cathode of diode D1, and the fifth pin is connected to the gate of field-effect transistor Q2; the in-phase terminal of operational amplifier U2 is connected to the VO terminal, the inverting terminal is connected to the Pi terminal, and the output terminal is connected to the source and Si terminal of field-effect transistor Q2; the first input terminal of AND gate U3 is connected to the output terminal of operational amplifier U5, the second input terminal is connected to the drain of field-effect transistor Q2 and the anode of diode D3, and the output terminal is connected to the anode of diode D5; the cathode of diode D3 is connected to the LO terminal.

[0018] Specifically, it also includes a switching unit, and the main control unit also includes several resistors, several diodes, an operational amplifier, an AND gate, and a counter. The operational amplifier U6 is connected to one end of the capacitor C2 in phase, and the output end is connected to the first input end of the AND gate U7; the second input end of the AND gate U7 is connected to the fifth pin of the trigger U1, and the output end is connected to the anode of the diode D2 and the anode of the diode D4; one end of the resistor R1 is connected to the Pi end; one end of the resistor R2 is connected to the cathode of the diode D1 and the cathode of the diode D2; the cathode of the diode D4 is connected to the cathode of the diode D5; the third pin of the counter U4 is connected to the Vi end, the eleventh pin is connected to the fifteenth pin, the fourteenth pin is connected to the anode of the diode D5, and the sixteenth pin is connected to the power supply; the other end of the resistor R1, the other end of the resistor R2, and the eighth pin of the counter U4 are grounded; the switching unit includes a solid-state relay and a resistor, one end of the resistor R16 is connected to the power supply, and the other end is connected to one end of the solid-state relay K2; the other end of the solid-state relay K2 is connected to the Pi end, one end of the coil is connected to the Vi end, and the other end of the coil is grounded.

[0019] Specifically, the number of the sub-detection units is consistent with the number of photovoltaic grid-connected control units.

[0020] Specifically, the number of the switch units is consistent with the number of photovoltaic grid-connected control units.

[0021] Specifically, the main control unit also includes several resistors, one end of the resistor R9 among the resistors is connected to one end of the resistor R8 and the non-inverting end of the operational amplifier U5, and the other end is connected to one end of the resistor R10 and the inverting end of the operational amplifier U6; the other end of the resistor R10 is connected to the power supply; the other end of the resistor R8 is grounded.

[0022] Specifically, the sub-detection unit further includes a resistor, one end of the resistor R6 is connected to the gate of the field effect transistor Q2, and the other end is grounded.

[0023] Specifically, the main control unit also includes several resistors, one end of the resistor R11 among the several resistors is connected to the third pin of the trigger U1; one end of the resistor R12 is connected to the thirteenth pin of the counter U4; one end of the resistor R15 is connected to the fifteenth pin of the counter U4; the other end of the resistor R11, the other end of the resistor R12, and the other end of the resistor R15 are grounded.

[0024] Specifically, the capacitor C1 and the capacitor C2 are adjustable capacitors.

[0025] The present invention can configure different control weights according to the distributed photovoltaic unit power, and provide distributed control mode and centralized control mode to achieve differentiated grid connection, and can be directly incorporated into the management and control when a new photovoltaic unit is added. In the distributed control mode, the control circuit consists of a main control unit and multiple sub-detection units. When the control quantity is increased, the number of sub-detection units is increased, and the weight is confirmed by the Pi amplitude input to configure, wherein IN is the total grid-connected signal for input into the main control unit, and the main control unit generates a VO signal to each sub-detection unit based on the IN state; the sub-detection unit feeds back the LO signal to the main control unit according to the input of VO and Pi, and at the same time feeds back the Si grid-connected sub-signal to the corresponding photovoltaic unit for grid connection; during the grid connection period, when the main control unit receives the LO signal fed back by any sub-detection unit, it generates an adjustable interrupt period signal to provide a response time window for the grid-connected operation and reset the main control unit for multiplexing, and repeats the above operation for the second-level photovoltaic units after the interruption ends until all are grid-connected.

[0026] In the centralized control mode, the control circuit consists of a main control unit and multiple switch units. When the maximum control quantity is increased, the digit of the counter U4 is changed. Compared with the distributed control mode, detection can be performed during the reset period of the main control unit. When the interruption period is adjusted too low, correction is forced to be performed to avoid multiple levels of simultaneous grid connection when the control quantity is too large. The control process is that the main control unit first generates a VO signal based on the IN signal state for self-test, and controls the switch unit based on the corresponding output of the Vi signal to feedback the configured Pi signal. The main control unit generates an adjustable interruption period signal according to the Pi and VO signals to provide a response time window for grid connection and reset the main control unit. During this period, the interruption period and reset status are detected, and after the interruption ends, the Pi signal corresponding to the second-level photovoltaic unit is provided to the main control unit. The above operation is repeated until all are connected to the grid.

[0027] The circuit principle of the distributed control mode is that before the total grid-connected signal IN is input, the power supply signal at the resistor R3 end is turned on through the transistor Q5 and resistor R13 loop to turn on the transistor Q6. The resistor R4 is used to divide the voltage with the resistor R3 to power the transistor Q5. After the voltage drop of IN through the diode D6, it can reach the cut-off threshold of the transistor Q5. The capacitor C1 makes VO at a low potential through the transistor Q6 and the ground loop. At the same time, the power supply voltage of the transistor Q4 emitter is turned on after passing through the resistor R5 loop, and then the capacitor C2 is pulled up to a high potential. The circuit is in standby state. When the total grid-connected signal IN is input, the signal is fed back to the base of the transistor Q5 through the diode D6. The emitter of the transistor Q5 is connected to the base. After the voltage difference is lower than the conduction threshold, the base input of the transistor Q6 is stopped, and the transistor Q6 is cut off. After the other circuit through the transistor Q3 and the resistor R5 is turned on, the VO potential voltage is gradually pulled up after being fed back to the capacitor C1 through the collector of the transistor Q3 and the resistor R7. The signal is fed back to the operational amplifier U2 in each sub-detection unit for comparison with the Pi voltage input at the in-phase and inverting ends. When the operational amplifier U2 of the sub-detection unit corresponding to the lower Pi is output, the output signal is fed back to the transistor Q1 through the field effect tube Q2 and the diode D3. The transistor Q1 is turned on, and the VO and LO of each sub-detection unit are connected in parallel. The Pi input corresponds to the weighted signal, and Si is fed back to the corresponding grid-connected sub-signal. The photovoltaic unit is connected to the grid. When the transistor Q1 is turned on, the auxiliary contact of the solid-state relay K1 coil is closed, and the power is fed back to the base of the transistor Q3 and the transistor Q4 through the auxiliary contact of the solid-state relay K1. The voltage difference from the emitter to the base of the transistor Q3 and the transistor Q4 is lower than the conduction threshold and then cut off. The capacitor C1 stops pulling up the VO potential and is in interruption. At the same time, the capacitor C2 is looped through the resistor R14, and the op amp U5 inverting terminal detects the voltage at the capacitor C2 terminal, the inverting terminal divider or the power input reference signal. When the voltage at the capacitor C2 terminal is pulled down to make the op amp U5 output, the output signal is fed back to the AND gate U3. The larger the capacity of the capacitor C2, the longer the interruption period. The AND gate U3 is in the op amp U2 After the output of the op amp U5, the feedback signal is input to the trigger U1 through the diode D5. The 5th pin of the trigger U1 is set to 1 and input to the gate of the field effect transistor Q2. The field effect transistor Q2 is cut off when the gate to source is lower than the negative voltage difference of the conduction. The resistor R6 is used to increase the parasitic capacitance discharge of the field effect transistor Q2 during high-speed control. There is no signal input to the base of the transistor Q1, the auxiliary contact of the solid-state relay K1 is disconnected, the transistor Q3 and the transistor Q4 are turned on again, the capacitor C1 pulls up the VO potential, and the capacitor C2 goes back to the high potential from the low potential to reset the main control unit, and waits for the sub-detection unit corresponding to the second-level photovoltaic unit to feedback the LO signal again and repeat the above process until all are connected to the grid.

[0028] In the circuit principle of the centralized control mode, the amplitude of Pi is controlled by the resistance value of resistor R16 and the shared voltage divider of resistor R1. The Pi end of each switch unit is connected in parallel, and the confirmation input is controlled by the confirmation grid-connected sub-signal Vi. The output pin of counter U4 is reduced by 1 to the actual controllable number. Pin 15 of counter U4 is connected in sequence with the output pins. The attached figure defaults to a connection diagram of 9 control quantities. Except for the output pin connected to pin 15 of counter U4, the remaining output pins output the corresponding confirmation grid-connected sub-signal Vi to the corresponding switch unit and the corresponding connected photovoltaic unit. At this time, multiple detection sub-units can be incorporated into the main control unit as separate detection circuits for multiplexing. When the control quantity is increased, the corresponding number of switch units can be added and the pin connection of counter U4 can be changed. When the control quantity is less than 9 bits, pin 15 of counter U4 is filled and moved up. When the maximum control quantity is increased, the number of bits of counter U4 is changed. The circuit inconsistency between the centralized control mode and the distributed control mode is that at the first level of grid connection, pin 3 of counter U4 outputs Vi to confirm the grid-connected sub-signal and waits for op amp U2 to output Si grid-connected sub-signal. After the above-mentioned circuit process of the distributed control mode, op amp U2 When the output and the 5-pin output signal of the trigger U1 is sent to the field effect tube Q2, the counter U4 converts the Vi output of the 3-pin to the output of the 2-pin (the attached figure only shows one switch unit and the corresponding Vi signal), and the switch unit corresponding to the 2-pin of the counter U4 is turned on. The weighted Pi signal voltage of the next level configuration is input to the inverting terminal of the operational amplifier U2. At the same time, the inverting terminal of the operational amplifier U6 detects the voltage signal of the capacitor C2 and compares it with the reference signal input at the inverting terminal. The inverting terminal of the operational amplifier U6 sets the reference signal through the voltage divider or power supply. The operational amplifier U6 compares the output and then feeds back To the AND gate U7, the output signal of the AND gate U7 is fed back to the 4th pin of the trigger U1 through the diode D2 and set to 1, and the other path is input to the 3th pin of the trigger U1 through the diode D4 to set the 5th pin to 0. After the VO potential is pulled up, the Si grid-connected sub-signal is output again. After receiving the Si and Vi signals, the photovoltaic unit connects the second-level photovoltaic to the grid, and repeats the above process until all are connected to the grid. During the grid-connected process, ensure that each level is forced to perform an interrupt cycle. Resistors R11, R12, and R15 are used to pull down the signal, and can be enabled by the chip when there is external control.

[0029] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A distributed photovoltaic grid-connected control circuit, characterized in that: The invention comprises a main control unit and a sub-detection unit, wherein the main control unit comprises a plurality of transistors, a plurality of resistors, an operational amplifier, a diode, a capacitor, and a solid-state relay. The base of the transistor Q1 among the plurality of transistors is connected to the LO terminal, and the emitter is connected to one end of the coil of the solid-state relay K1; the base of the transistor Q3 is connected to the base of the transistor Q4, one end of the solid-state relay K1, one end of the resistor R5, the collector is connected to one end of the resistor R7, and the emitter is connected to the anode and IN terminal of the diode D6; the collector of the transistor Q4 is connected to the inverting terminal of the operational amplifier U5, one end of the capacitor C2, and one end of the resistor R14; the base of the transistor Q5 is connected to the cathode of the diode D6, one end of the resistor R13, the emitter is connected to one end of the resistor R3, one end of the resistor R4, and the collector is connected to the base of the transistor Q6; the collector of the transistor Q6 is connected to one end of the capacitor C1, the other end of the resistor R7, and the VO terminal; the other end of the solid-state relay K1, the collector of the transistor Q1, the emitter of the transistor Q4, the The other end of resistor R3 is connected to the power supply; the other end of the coil of solid-state relay K1, the emitter of transistor Q6, the other end of resistor R4, the other end of resistor R5, the other end of resistor R13, the other end of resistor R14, the other end of capacitor C1, and the other end of capacitor C2 are grounded; the sub-detection unit includes several diodes, triggers, operational amplifiers, AND gates, and field-effect transistors. The first pin of the trigger U1 is connected to the power supply, the second pin is connected to the sixth pin and the anode of diode D1, the third pin is connected to the cathode of diode D5, the fourth pin is connected to the cathode of diode D1, and the fifth pin is connected to the gate of field-effect transistor Q2; the in-phase terminal of operational amplifier U2 is connected to the VO terminal, the inverting terminal is connected to the Pi terminal, and the output terminal is connected to the source and Si terminal of field-effect transistor Q2; the first input terminal of AND gate U3 is connected to the output terminal of operational amplifier U5, the second input terminal is connected to the drain of field-effect transistor Q2 and the anode of diode D3, and the output terminal is connected to the anode of diode D5; the cathode of diode D3 is connected to the LO terminal.

2. The distributed photovoltaic grid-connected control circuit according to claim 1, characterized in that: It also includes a switch unit, and the main control unit also includes a number of resistors, a number of diodes, an operational amplifier, an AND gate, and a counter. The operational amplifier U6 is connected to one end of the capacitor C2 in phase, and the output end is connected to the first input end of the AND gate U7; the second input end of the AND gate U7 is connected to the fifth pin of the trigger U1, and the output end is connected to the anode of the diode D2 and the anode of the diode D4; one end of the resistor R1 is connected to the Pi end; one end of the resistor R2 is connected to the cathode of the diode D1 and the cathode of the diode D2; the cathode of the diode D4 is connected to the cathode of the diode D5; the third pin of the counter U4 is connected to the Vi end, the eleventh pin is connected to the fifteenth pin, the fourteenth pin is connected to the anode of the diode D5, and the sixteenth pin is connected to the power supply; the other end of the resistor R1, the other end of the resistor R2, and the eighth pin of the counter U4 are grounded; the switch unit includes a solid-state relay and a resistor, one end of the resistor R16 is connected to the power supply, and the other end is connected to one end of the solid-state relay K2; the other end of the solid-state relay K2 is connected to the Pi end, one end of the coil is connected to the Vi end, and the other end of the coil is grounded.

3. The distributed photovoltaic grid-connected control circuit according to claim 1, characterized in that: The number of the sub-detection units is consistent with the number of photovoltaic grid-connected control units.

4. The distributed photovoltaic grid-connected control circuit according to claim 2, characterized in that: The number of switch units is consistent with the number of photovoltaic grid-connected control units.

5. The distributed photovoltaic grid-connected control circuit according to claim 1, characterized in that: The main control unit also includes a plurality of resistors, one end of the resistor R9 of the plurality of resistors is connected to one end of the resistor R8 and the non-inverting terminal of the operational amplifier U5, and the other end is connected to one end of the resistor R10 and the inverting terminal of the operational amplifier U6; the other end of the resistor R10 is connected to the power supply; the other end of the resistor R8 is grounded.

6. The distributed photovoltaic grid-connected control circuit according to claim 1, characterized in that: The sub-detection unit further includes a resistor, one end of the resistor R6 is connected to the gate of the field effect transistor Q2, and the other end is grounded.

7. The distributed photovoltaic grid-connected control circuit according to claim 2, characterized in that: The main control unit also includes several resistors, one end of the resistor R11 among the several resistors is connected to the third pin of the trigger U1; one end of the resistor R12 is connected to the thirteenth pin of the counter U4; one end of the resistor R15 is connected to the fifteenth pin of the counter U4; the other end of the resistor R11, the other end of the resistor R12, and the other end of the resistor R15 are grounded.

8. The distributed photovoltaic grid-connected control circuit according to claim 1, characterized in that: The capacitor C1 and the capacitor C2 are adjustable capacitors.

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