A distributed photovoltaic control circuit
By adopting a selective isolation control scheme based on the characteristics of circuit breaker faults in a distributed photovoltaic system, and utilizing a control unit composed of switching transistors, resistors, and operational amplifiers, selective isolation during faults is achieved. This solves the problems of fault propagation and equipment damage in existing technologies, and improves the reliability of the system and the reliability of power supply.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NO 7 ENG CO OF CHINA RAILWAY NO 8 ENG GRP CO LTD
- Filing Date
- 2026-02-24
- Publication Date
- 2026-05-26
AI Technical Summary
Existing distributed photovoltaic systems lack selective isolation capabilities in the event of a fault, leading to fault propagation and equipment damage. Current technologies require an emergency disconnection of all power sources, resulting in a loss of power supply to the load.
A selective isolation control scheme based on the QF fault characteristics of circuit breakers is adopted. The control unit, composed of several switching transistors, resistors, operational amplifiers and diodes, realizes the automatic detection and isolation of circuit breakers. By judging different fault types, the photovoltaic group or busbar is selectively isolated to prevent the fault from spreading.
It enables selective isolation of photovoltaic modules or busbars in case of faults, avoiding equipment damage, ensuring stable system operation, preventing circuit breaker malfunctions under unauthorized conditions, and improving system reliability and power supply reliability.
Smart Images
Figure CN121749081B_ABST
Abstract
Description
Technical Field
[0001] This invention pertains to photovoltaic power supply control, specifically relating to a distributed photovoltaic control circuit. Background Technology
[0002] like Figure 1 and Figure 2 In the typical distributed photovoltaic (PV) grid-connected architecture shown, the system typically adopts a "trunk-branch" topology: a common distribution transformer supplies power to the entire area via the trunk line; multiple distributed PV units are connected to the system as "loads," each PV unit containing a PV array, a DC / AC inverter, and its output QF circuit breaker; the outputs of all PV units ultimately converge on a busbar and are connected to the trunk line from the transformer via a main grid-connected QF circuit breaker located at the busbar point, jointly supplying power to the common load. However, existing systems suffer from a lack of selective fault isolation capability in actual operation. For example, when a QF circuit breaker in a load branch fails (e.g., malfunction, false tripping, or internal short circuit), due to the multi-source nature of the PV system, the fault point may cause reverse current backflow to the trunk line or other normal branches, leading to an expansion of the fault range, equipment damage, or even system paralysis. To avoid such situations, existing technologies typically involve emergency disconnection of the main circuit breaker and all photovoltaic output circuit breakers to cut off all possible power sources. While this approach can prevent the fault from spreading during daytime sunlight, it also causes all loads to stop receiving power. Summary of the Invention
[0003] In view of this, to solve the above problems, this application proposes a control scheme that can selectively isolate faults based on the fault characteristics of the circuit breaker QF, ensuring that photovoltaic power generation will not be interrupted due to other fault points. The scheme includes a control unit corresponding to the number of loads. The control unit includes several switching transistors, several resistors, several operational amplifiers, and several diodes. Among the switching transistors, the gate of P-type MOSFET Q2 is connected to one end of resistor R7, the gate of P-type MOSFET Q3 is connected to the coil QFA_COIL of circuit breaker QFA, the source is connected to the normally closed terminal NC of circuit breaker QFA, and the drain is connected to the anode of diode D1 and one end of resistor R1. The common terminal C of circuit breaker QFA is connected to the power supply, and the normally open terminal NO is connected to the gate of P-type MOSFET Q3 and the gate of N-type MOSFET Q1. The drain of N-type MOSFET Q1 is connected to the other end of resistor R7. One end of resistor R8 is connected to the source of resistor R4 and the anode of diode D2; the drain of P-type MOSFET Q3 is connected to one end of resistor R6 and the non-inverting input of operational amplifier U1; the cathodes of diodes D2 and D1 are connected to the non-inverting input of operational amplifier U2; the inverting input of operational amplifier U2 is connected to the inverting input of operational amplifier U1 and a minimum voltage greater than ground and less than the input of the non-inverting input of operational amplifier U2 is set, and the output is connected to the base of N-type transistor Q4; the emitter of N-type transistor Q4 is connected to the source of P-type MOSFET Q5, and the collector is connected to the power supply; the gate of P-type MOSFET Q5 is connected to the output of operational amplifier U1, and the drain is connected to the circuit breaker QFB coil QFB_COIL; the other ends of resistors R1, R4, R6, and R8 are connected to the ground terminal.
[0004] This scheme implements automatic detection and control when a circuit breaker fails to operate, maloperates, or experiences an internal short circuit. Based on the fault type, assuming circuit breaker QFA is currently in the closed state and a closing signal exists, the coil QFA_COIL of circuit breaker QFA is powered via signal switch KEY1. Simultaneously, the VCC signal is input through connector H1: one path to the gate of P-type MOSFET Q2, causing Q2 to turn off; another path to the gate of P-type MOSFET Q3; and the third path, after voltage division by resistors R7 and R8, is input to the drain of N-type MOSFET Q1. At the same time, the main contacts of circuit breaker QFA close, closing the common terminal (C) and normally open terminal (NO) of circuit breaker QFA. VCC, after passing through the common terminal (C) and normally open terminal (NO) of circuit breaker QFA, is input to the gates of P-type MOSFET Q3 and N-type MOSFET Q1, respectively. P-type MOSFET Q3 is cut off due to a voltage difference below the conduction negative differential, while N-type MOSFET Q1 is cut off due to a voltage difference above the conduction negative differential. When the positive voltage difference is turned on, the voltage at the voltage divider point of resistors R7 and R8 is input to the non-inverting input of operational amplifier U2 through the drain and source of N-type MOSFET Q1 and diode D2. The voltage at the non-inverting input of operational amplifier U2 is greater than the voltage at the inverting input. Operational amplifier U2 outputs a signal to the base of N-type transistor Q4, and N-type transistor Q4 turns on. When P-type MOSFET Q3 is turned off, the voltage at the non-inverting input of operational amplifier U1 is less than the voltage at the inverting input through the resistor R6 circuit. P-type MOSFET Q5 is in a negative voltage difference conducting state. At this time, VCC is input to the coil QFB_COIL of circuit breaker QFB through the collector and emitter of N-type transistor Q4, the source and drain of P-type MOSFET Q5, and connector H2. The main contacts of circuit breaker QFB close, and the photovoltaic array is fed back to the bus line through the main contacts of circuit breaker QFB and circuit breaker QFA.
[0005] Assuming the circuit breaker QFA is in the open state with no closing signal, the gates of P-type MOSFETs Q2 and Q3 are pulled down through resistor R5 and the grounding circuit. The common terminal C and normally closed terminal NC of the circuit breaker QFA are connected. The VCC power supply is input to the non-inverting input of operational amplifier U2 through the common terminal, normally closed terminal NC, gate and source of P-type MOSFET Q2, resistor R1, and diode D1 of the circuit breaker QFA. The inverting input of operational amplifier U2 sets a reference voltage through the power supply or a voltage divider between resistors R3 and R2. The voltage value is greater than zero and less than the supply voltage between resistors R7 and R8 minus the voltage drop of N-type MOSFET Q1 and diode D2. Subsequently, the P-type MOSFET... When transistor Q2 is turned on, the output signal is sent to N-type transistor Q4. When N-type transistor Q4 is turned on, there is no input to the source of P-type MOSFET Q3. The non-inverting input of operational amplifier U1 is connected to the ground circuit through resistor R6. The voltage at the non-inverting input of operational amplifier U1 is less than that at the inverting input. P-type MOSFET Q5 is in a negative voltage difference conducting state. At this time, VCC is input to the coil QFB_COIL of circuit breaker QFB through the collector and emitter of N-type transistor Q4, the source and drain of P-type MOSFET Q5, and connector H2. The main contacts of circuit breaker QFB are closed. The photovoltaic array is fed back to the main contacts of circuit breaker QFA through circuit breaker QFB and waits for circuit breaker QFA to turn on before being input to the bus line.
[0006] When the circuit breaker is in the closed state and a maloperation or failure to operate occurs, the common terminal C and normally open terminal NO of the original circuit breaker QFA are disconnected, and the common terminal C and normally closed terminal are closed. The gate of N-type MOSFET Q1 and the source of P-type MOSFET Q3 have no input. At the same time, P-type MOSFET Q2 is turned off because the voltage input from VCC to the gate of P-type MOSFET Q2 when the signal switch KEY1 is closed causes P-type MOSFET Q2 to be in a positive voltage or below the negative voltage conduction threshold state. The non-inverting terminal of operational amplifier U2 has no input, and its voltage is less than the voltage of the inverting terminal. Operational amplifier U2 has no output. N-type transistor Q4 is turned off, and the source of P-type MOSFET Q5 has no input. The coil QFB_COIL of circuit breaker QFB is de-energized, and the main contacts of circuit breaker QFB are opened to complete the isolation of photovoltaic and bus line.
[0007] When the circuit breaker is in the open state and a short-circuit fault occurs, the common terminal C and normally open terminal NO of the circuit breaker QFA are closed. The gate of the P-type MOSFET Q3 is turned on through the resistor R5 and the grounding circuit. The VCC power supply is fed back to the non-inverting terminal of the operational amplifier U1 through the common terminal C of the circuit breaker QFA, the normally open terminal NO, the source and drain of the P-type MOSFET Q3, and the resistor R6 circuit. The voltage at the non-inverting terminal of the operational amplifier U1 is greater than the voltage at the inverting terminal of the operational amplifier U1. The operational amplifier U1 outputs a signal to the gate of the P-type MOSFET Q5. The P-type MOSFET Q5 is turned off when it is under positive voltage or below the negative voltage turn-on threshold. The coil QFB_COIL of the circuit breaker QFB is de-energized, and the main contacts of the circuit breaker QFB are opened to complete the isolation of the photovoltaic and the bus line.
[0008] Furthermore, a diode D3 is connected in series between the output terminal of operational amplifier U1 and the gate of P-type MOSFET Q5; the anode of diode D3 is connected to the output terminal of operational amplifier U1, the non-inverting terminal of operational amplifier U3, the collector of P-type MOSFET Q6, and one end of resistor R18; the cathode of diode D3 is connected to one end of resistor R9, the gate of P-type MOSFET Q5, and the cathode of diode D6; the anode of diode D6 is connected to the output terminal of operational amplifier U5 and one end of resistor R14; the inverting terminal of operational amplifier U5 is connected to the other end of resistor R14; the non-inverting terminal is connected to the cathode of diode D5, one end of resistor R10, one end of resistor R11, the cathode of diode D4, and the non-inverting terminal of operational amplifier U4; the inverting terminal of operational amplifier U4 is connected to one end of resistor R12 and one end of resistor R13, and its output terminal is connected to the anode of diode D5; the inverting terminal of operational amplifier U3 is connected to the inverting terminal of operational amplifier U1, and its output terminal is connected to the diode D18. 4. Anode connection; The base of N-type transistor Q7 is connected to the output terminal of operational amplifier U2, the collector is connected to the emitter of P-type transistor Q6 and the power supply, the emitter is connected to the base of P-type transistor Q6 and one end of resistor R17; the collector of P-type transistor Q6 is connected to one end of resistor R18; the other ends of resistors R17, R18, R13, and R11 are connected to the ground terminal; the other ends of resistors R10 and R12 are connected to the power supply. This scheme achieves isolation blocking and authorized restoration. Compared with the above scheme, this scheme can block the open state of circuit breaker QFB when the main contacts of circuit breaker QFB are opened due to any fault such as failure to operate, maloperation, or internal short circuit, and shield the normal control command of signal switch KEY1 to prevent circuit breaker QFB from being accidentally closed due to accidental contact of signal switch KEY1 in an unauthorized state.
[0009] Assuming the current fault is a failure to operate or a maloperation while the circuit breaker is closed, causing the common terminal C and normally closed terminal NC of the current circuit breaker QFA to remain or change to a closed state, after the signal circuit described above for when the circuit breaker is in a closed state and a maloperation or failure to operate fault occurs, the operational amplifier U2 will have no output. The VCC power supply will then pass through the emitter, base, and resistor R17 of the P-type transistor Q6, turning on the P-type transistor Q6. VCC will then pass through the emitter, collector, and resistor R18 of the P-type transistor Q6 and be fed back to the non-inverting input of the operational amplifier U3. The inverting input of the operational amplifier U3 will sample the reference signal from the inverting input of the operational amplifier U1, compare it, and output the signal. Reference voltages will be set at the non-inverting and inverting inputs of the operational amplifier U4, with the inverting input reference voltage being greater than the non-inverting input reference voltage. When the operational amplifier... When the amplifier U3 outputs, the signal at the output terminal of operational amplifier U3 is fed back to the non-inverting terminal of operational amplifier U4 via diode D4. The output signal of operational amplifier U4 is fed back to operational amplifier U5 via diode D5. Operational amplifier U5 and resistor R17 form an isolation follower circuit and are input to the gate of P-type MOSFET Q5 via diode D6. When P-type MOSFET Q5 is turned off, coil QFB_COIL is de-energized, and the main contacts of circuit breaker QFB are opened. When the coil QFA_COIL of circuit breaker QFA is switched and the current state of operational amplifier U2 is changed by the subsequent circuit, the signal at the output terminal of operational amplifier U4 is fed back to the non-inverting terminal of operational amplifier U5 via diode D5. The potential at the non-inverting terminal of operational amplifier U4 is synchronously pulled up to complete the closed-loop locking.
[0010] Assuming the current fault is a short circuit causing the common terminal C and normally open terminal NO of the current circuit breaker QFA to be closed, when the operational amplifier U1, which is in the tripped state and experiences a short circuit fault, outputs, the signal from operational amplifier U1 will also be fed back to the non-inverting input of operational amplifier U3. The inverting input of operational amplifier U3 samples the reference signal from the inverting input of operational amplifier U1, compares it, and outputs the signal. When operational amplifier U3 outputs, the signal from its output terminal is fed back to the non-inverting input of operational amplifier U4 via diode D4. The output signal from operational amplifier U4 is fed back to operational amplifier U5 via diode D5. Operational amplifier U5 and resistor R17 form an isolated follower circuit, which is input to the P-type MOSFET Q5 via diode D6. When the gate of the P-type MOSFET Q5 is cut off, the coil QFB_COIL is de-energized, and the main contacts of the circuit breaker QFB are open, when the coil QFA_COIL of the circuit breaker QFA is switched and the current state of the operational amplifier U1 is changed by the subsequent circuit, the output signal of the operational amplifier U4 is sent to the non-inverting input of the operational amplifier U5 via diode D5. This signal will also form feedback through the non-inverting input of the operational amplifier U4, and the potential of the non-inverting input of the operational amplifier U4 will be synchronously pulled up to complete the closed-loop lockout. When the authorization is restored, the signal switch KEY2 is closed, and the VCC power supply is input to the operational amplifier U4 through the signal switch KEY2. The voltage at the inverting input of the operational amplifier U4 is greater than the voltage at the non-inverting input, the operational amplifier U4 has no output, the diode D5 is cut off, and the circuit returns to the fault-free control state.
[0011] Furthermore, it also includes several capacitors. Among the several resistors, resistor R15 is connected in series between the drain of the P-type MOS transistor Q3 and the non-inverting input of operational amplifier U1; the non-inverting input of operational amplifier U1 is connected to one end of C1; one end of resistor R16 is connected to one end of C2 and the non-inverting input of operational amplifier U2; the other end of resistor R16, the other end of C1, the other end of C2 are connected to the ground terminal.
[0012] This solution addresses the issue of deviations in mechanical and signal response speeds by using resistors R15 and C1, and resistors R16 and C2, to reduce the signal output sensitivity of operational amplifiers U1 and U2. Before the QFA_COIL signal from the circuit breaker QFA coil is input to operational amplifier U1 via the P-type MOSFET Q3, energy is stored through resistors R15 and C1. When the voltage at C1 is pulled up to the voltage divider point of resistors R3 and R2, operational amplifier U1 then outputs the signal, reducing output sensitivity and preventing issues caused by the signal switch KEY1 signal being disconnected. Before the circuit breaker QFA operates, the operational amplifier U1 may fail to output; when the N-type MOSFET Q1 and P-type MOSFET Q2 are turned on and there is input at the drain of the corresponding N-type MOSFET Q1 and the source of the corresponding P-type MOSFET Q2, the signal is fed back to the non-inverting input of the operational amplifier U2 through diodes D2 and D1 and stored in C2. When the voltage at the C2 terminal is pulled up to the voltage divider point of resistors R3 and R2, the operational amplifier U2 outputs, thus avoiding the dead zone of the operational amplifier U2 that may be caused by the switching of the signal switch KEY1 when the circuit breaker QFA is fault-free.
[0013] Furthermore, a connector H1 is connected in series between the gate of the P-type MOSFET Q2 and the coil QFA_COIL of the circuit breaker QFA. Connector H1 and the coil QFA_COIL of the circuit breaker QFA are also connected to one end of the signal switch KEY1, and the other end of the signal switch KEY1 is connected to the power supply. Connector H2 is also connected in series between the drain of the P-type MOSFET Q5 and the coil QFB_COIL of the circuit breaker QFB. In this scheme, the coils of the circuit breaker QFA and the circuit breaker QFB can also be connected by jumpers through connectors H1 and H2.
[0014] Furthermore, among the resistors, one end of resistor R3 is connected to the power supply, and the other end is connected to the inverting input of operational amplifier U2 and one end of resistor R2; the other end of resistor R2 is connected to the ground terminal; this scheme uses resistor voltage division to replace the power supply to input reference signals to operational amplifiers U2, operational amplifier U1, and operational amplifier U3.
[0015] Furthermore, the connection terminals of resistors R12 and R13 are also connected to one end of signal switch KEY2, and the other end of signal switch KEY2 is connected to the power supply; this scheme enables the circuit breaker QFA coil signal to be obtained through control of signal switch KEY. Attached Figure Description
[0016] Figure 1 and Figure 2 A schematic diagram of the existing grid-connected architecture provided by the present invention.
[0017] Figure 3 A schematic diagram of the control circuit connection architecture provided by the present invention.
[0018] Figure 4 A schematic diagram of the control unit circuit provided by the present invention.
[0019] Figure 5 This is a schematic diagram of another control unit circuit provided by the present invention.
[0020] Figure 6 This is a schematic diagram of another control unit circuit provided by the present invention.
[0021] Figure 7 This is a schematic diagram of another control unit circuit provided by the present invention. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0023] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.
[0024] In one embodiment, the goal is to achieve automatic detection and control of circuit breakers in case of failure to operate, maloperation, or internal short circuit. Based on the fault type, assuming circuit breaker QFA is currently in the closed state and a closing signal exists, the coil QFA_COIL of circuit breaker QFA is powered via signal switch KEY1. Simultaneously, the VCC signal is input through connector H1, one path to the gate of P-type MOSFET Q2 (causing Q2 to turn off), another path to the gate of P-type MOSFET Q3, and the third path, after voltage division by resistors R7 and R8, is input to the drain of N-type MOSFET Q1. At the same time, the main contacts of circuit breaker QFA close, closing the common terminal C and normally open terminal NO. VCC, after passing through the common terminal C and normally open terminal NO of circuit breaker QFA, is input to the gates of P-type MOSFET Q3 and N-type MOSFET Q1, respectively. P-type MOSFET Q3 is turned off due to a voltage difference below the conduction negative differential, while N-type MOSFET Q1 is turned off due to a voltage difference above the conduction negative differential. When the positive voltage difference is turned on, the voltage at the voltage divider point of resistors R7 and R8 is input to the non-inverting input of operational amplifier U2 through the drain and source of N-type MOSFET Q1 and diode D2. The voltage at the non-inverting input of operational amplifier U2 is greater than the voltage at the inverting input. Operational amplifier U2 outputs a signal to the base of N-type transistor Q4, and N-type transistor Q4 turns on. When P-type MOSFET Q3 is turned off, the voltage at the non-inverting input of operational amplifier U1 is less than the voltage at the inverting input through the resistor R6 circuit. P-type MOSFET Q5 is in a negative voltage difference conducting state. At this time, VCC is input to the coil QFB_COIL of circuit breaker QFB through the collector and emitter of N-type transistor Q4, the source and drain of P-type MOSFET Q5, and connector H2. The main contacts of circuit breaker QFB close, and the photovoltaic array is fed back to the bus line through the main contacts of circuit breaker QFB and circuit breaker QFA.
[0025] Assuming the circuit breaker QFA is in the open state with no closing signal, the gates of P-type MOSFETs Q2 and Q3 are pulled down through resistor R5 and the grounding circuit. The common terminal C and normally closed terminal NC of the circuit breaker QFA are connected. The VCC power supply is input to the non-inverting input of operational amplifier U2 through the common terminal, normally closed terminal NC, gate and source of P-type MOSFET Q2, resistor R1, and diode D1 of the circuit breaker QFA. The inverting input of operational amplifier U2 sets a reference voltage through the power supply or a voltage divider between resistors R3 and R2. The voltage value is greater than zero and less than the supply voltage between resistors R7 and R8 minus the voltage drop of N-type MOSFET Q1 and diode D2. Subsequently, the P-type MOSFET... When transistor Q2 is turned on, the output signal is sent to N-type transistor Q4. When N-type transistor Q4 is turned on, there is no input to the source of P-type MOSFET Q3. The non-inverting input of operational amplifier U1 is connected to the ground circuit through resistor R6. The voltage at the non-inverting input of operational amplifier U1 is less than that at the inverting input. P-type MOSFET Q5 is in a negative voltage difference conducting state. At this time, VCC is input to the coil QFB_COIL of circuit breaker QFB through the collector and emitter of N-type transistor Q4, the source and drain of P-type MOSFET Q5, and connector H2. The main contacts of circuit breaker QFB are closed. The photovoltaic array is fed back to the main contacts of circuit breaker QFA through circuit breaker QFB and waits for circuit breaker QFA to turn on before being input to the bus line.
[0026] When the circuit breaker is in the closed state and a maloperation or failure to operate occurs, the common terminal C and normally open terminal NO of the original circuit breaker QFA are disconnected, and the common terminal C and normally closed terminal are closed. The gate of N-type MOSFET Q1 and the source of P-type MOSFET Q3 have no input. At the same time, P-type MOSFET Q2 is turned off because the voltage input from VCC to the gate of P-type MOSFET Q2 when the signal switch KEY1 is closed causes P-type MOSFET Q2 to be in a positive voltage or below the negative voltage conduction threshold state. The non-inverting terminal of operational amplifier U2 has no input, and its voltage is less than the voltage of the inverting terminal. Operational amplifier U2 has no output. N-type transistor Q4 is turned off, and the source of P-type MOSFET Q5 has no input. The coil QFB_COIL of circuit breaker QFB is de-energized, and the main contacts of circuit breaker QFB are opened to complete the isolation of photovoltaic and bus line.
[0027] When the circuit breaker is in the open state and a short-circuit fault occurs, the common terminal C and normally open terminal NO of the circuit breaker QFA are closed. The gate of the P-type MOSFET Q3 is turned on through the resistor R5 and the grounding circuit. The VCC power supply is fed back to the non-inverting terminal of the operational amplifier U1 through the common terminal C of the circuit breaker QFA, the normally open terminal NO, the source and drain of the P-type MOSFET Q3, and the resistor R6 circuit. The voltage at the non-inverting terminal of the operational amplifier U1 is greater than the voltage at the inverting terminal of the operational amplifier U1. The operational amplifier U1 outputs a signal to the gate of the P-type MOSFET Q5. The P-type MOSFET Q5 is turned off when it is under positive voltage or below the negative voltage turn-on threshold. The coil QFB_COIL of the circuit breaker QFB is de-energized, and the main contacts of the circuit breaker QFB are opened to complete the isolation of the photovoltaic and the bus line.
[0028] like Figure 5 As shown, in one embodiment, a scheme with isolation blocking and authorized recovery is proposed based on the above scheme. Compared with the above scheme, this scheme can implement closed-loop locking of the tripping state of the circuit breaker QFB when the main contacts of the circuit breaker QFB are opened due to any fault such as failure to operate, erroneous operation or internal short circuit, and shield the normal control command of the signal switch KEY1 to prevent the circuit breaker QFB from being accidentally closed due to accidental contact of the signal switch KEY1 in an unauthorized state.
[0029] Assuming the current fault is a failure to operate or a maloperation while the circuit breaker is closed, causing the common terminal C and normally closed terminal NC of the current circuit breaker QFA to remain or change to a closed state, after the signal circuit described above for when the circuit breaker is in a closed state and a maloperation or failure to operate fault occurs, the operational amplifier U2 will have no output. The VCC power supply will then pass through the emitter, base, and resistor R17 of the P-type transistor Q6, turning on the P-type transistor Q6. VCC will then pass through the emitter, collector, and resistor R18 of the P-type transistor Q6 and be fed back to the non-inverting input of the operational amplifier U3. The inverting input of the operational amplifier U3 will sample the reference signal from the inverting input of the operational amplifier U1, compare it, and output the signal. Reference voltages will be set at the non-inverting and inverting inputs of the operational amplifier U4, with the inverting input reference voltage being greater than the non-inverting input reference voltage. When the operational amplifier... When the amplifier U3 outputs, the signal at the output terminal of operational amplifier U3 is fed back to the non-inverting terminal of operational amplifier U4 via diode D4. The output signal of operational amplifier U4 is fed back to operational amplifier U5 via diode D5. Operational amplifier U5 and resistor R17 form an isolation follower circuit and are input to the gate of P-type MOSFET Q5 via diode D6. When P-type MOSFET Q5 is turned off, coil QFB_COIL is de-energized, and the main contacts of circuit breaker QFB are opened. When the coil QFA_COIL of circuit breaker QFA is switched and the current state of operational amplifier U2 is changed by the subsequent circuit, the signal at the output terminal of operational amplifier U4 is fed back to the non-inverting terminal of operational amplifier U5 via diode D5. The potential at the non-inverting terminal of operational amplifier U4 is synchronously pulled up to complete the closed-loop locking.
[0030] Assuming the current fault is a short circuit causing the common terminal C and normally open terminal NO of the current circuit breaker QFA to be closed, when the operational amplifier U1, which is in the tripped state and experiences a short circuit fault, outputs, the signal from operational amplifier U1 will also be fed back to the non-inverting input of operational amplifier U3. The inverting input of operational amplifier U3 samples the reference signal from the inverting input of operational amplifier U1, compares it, and outputs the signal. When operational amplifier U3 outputs, the signal from its output terminal is fed back to the non-inverting input of operational amplifier U4 via diode D4. The output signal from operational amplifier U4 is fed back to operational amplifier U5 via diode D5. Operational amplifier U5 and resistor R17 form an isolated follower circuit, which is input to the P-type MOSFET Q5 via diode D6. When the gate of the P-type MOSFET Q5 is cut off, the coil QFB_COIL is de-energized, and the main contacts of the circuit breaker QFB are open, when the coil QFA_COIL of the circuit breaker QFA is switched and the current state of the operational amplifier U1 is changed by the subsequent circuit, the output signal of the operational amplifier U4 is sent to the non-inverting input of the operational amplifier U5 via diode D5. This signal will also form feedback through the non-inverting input of the operational amplifier U4, and the potential of the non-inverting input of the operational amplifier U4 will be synchronously pulled up to complete the closed-loop lockout. When the authorization is restored, the signal switch KEY2 is closed, and the VCC power supply is input to the operational amplifier U4 through the signal switch KEY2. The voltage at the inverting input of the operational amplifier U4 is greater than the voltage at the non-inverting input, the operational amplifier U4 has no output, the diode D5 is cut off, and the circuit returns to the fault-free control state.
[0031] See Figure 6 and Figure 7In one embodiment, due to the deviation in mechanical response and signal response speed, resistors R15 and C1 and resistors R16 and C2 are set to reduce the signal output sensitivity of operational amplifiers U1 and U2. Before the coil QFA_COIL signal of circuit breaker QFA is input to operational amplifier U1 via P-type MOSFET Q3, energy is stored through resistors R15 and C1. When the voltage at the C1 terminal is pulled up to the voltage divider point of resistors R3 and R2, operational amplifier U1 then outputs, reducing output sensitivity and avoiding possible faulty output of operational amplifier U1 before circuit breaker QFA operates after the signal switch KEY1 signal is disconnected. When N-type MOSFET Q1 and P-type MOSFET Q2 are turned on and the corresponding drain of N-type MOSFET Q1, After the P-type MOSFET Q2 has an input at its source, the signal is fed back to the non-inverting input of operational amplifier U2 via diodes D2 and D1. Energy is stored in C2. When the voltage at C2 is pulled up to the voltage divider point of resistors R3 and R2, operational amplifier U2 outputs. This avoids the dead zone of operational amplifier U2 that may be caused by switching signal switch KEY1 when circuit breaker QFA is fault-free. When the coils of circuit breaker QFA and circuit breaker QFB are connected by connectors H1 and H2, it is convenient to connect the series current drive amplifier circuit to increase the coil drive current. Alternatively, when the load is sufficient, connectors H1 and H2 can be removed and the coil can be directly connected. The circuit breaker QFA coil signal is obtained not only by the control of signal switch KEY, but also by input from the upper-level control circuit, such as a processor or microcontroller.
Claims
1. A distributed photovoltaic control circuit, characterized in that, The control unit includes a control unit corresponding to the number of loads. The control unit comprises several switching transistors, several resistors, several operational amplifiers, and several diodes. Among the switching transistors, the gate of P-type MOSFET Q2 is connected to one end of resistor R7, the gate of P-type MOSFET Q3 is connected to the coil QFA_COIL of circuit breaker QFA, the source is connected to the normally closed terminal NC of circuit breaker QFA, and the drain is connected to the anode of diode D1 and one end of resistor R1. The common terminal C of circuit breaker QFA is connected to the power supply, and the normally open terminal NO is connected to the gate of P-type MOSFET Q3 and the gate of N-type MOSFET Q1. The drain of N-type MOSFET Q1 is connected to the other end of resistor R7 and one end of resistor R8, and the source is connected to one end of resistor R4 and the anode of diode D2. The P-type MOSFET... The drain of S-transistor Q3 and one end of resistor R6 are connected to the non-inverting input of operational amplifier U1; the cathodes of diodes D2 and D1 are connected to the non-inverting input of operational amplifier U2; the inverting input of operational amplifier U2 is connected to the inverting input of operational amplifier U1 and a minimum voltage greater than ground and less than the input of the non-inverting input of operational amplifier U2 is set, and the output is connected to the base of N-type transistor Q4; the emitter of N-type transistor Q4 is connected to the source of P-type MOSFET Q5, and the collector is connected to the power supply; the gate of P-type MOSFET Q5 is connected to the output of operational amplifier U1, and the drain is connected to the circuit breaker QFB coil QFB_COIL; the other ends of resistors R1, R4, R6, and R8 are connected to the ground.
2. The distributed photovoltaic control circuit according to claim 1, characterized in that, A diode D3 is connected in series between the output terminal of operational amplifier U1 and the gate of P-type MOSFET Q5. The anode of diode D3 is connected to the output terminal of operational amplifier U1, the non-inverting terminal of operational amplifier U3, the collector of P-type MOSFET Q6, and one end of resistor R18. The cathode of diode D3 is connected to one end of resistor R9, the gate of P-type MOSFET Q5, and the cathode of diode D6. The anode of diode D6 is connected to the output terminal of operational amplifier U5 and one end of resistor R14. The inverting terminal of operational amplifier U5 is connected to the other end of resistor R14. The non-inverting terminal is connected to the cathode of diode D5, one end of resistor R10, one end of resistor R11, the cathode of diode D4, and the non-inverting terminal of operational amplifier U4. Operational amplifier U4 is inverted... The output terminal is connected to one end of resistor R12 and one end of resistor R13, and the output terminal is connected to the anode of diode D5; the inverting input of operational amplifier U3 is connected to the inverting input of operational amplifier U1, and the output terminal is connected to the anode of diode D4; the base of N-type transistor Q7 is connected to the output terminal of operational amplifier U2, the collector is connected to the emitter of P-type transistor Q6 and the power supply, the emitter is connected to the base of P-type transistor Q6 and one end of resistor R17; the collector of P-type transistor Q6 is connected to one end of resistor R18; the other ends of resistors R17, R18, R13, and R11 are connected to ground; the other ends of resistors R10 and R12 are connected to the power supply.
3. The distributed photovoltaic control circuit according to claim 1 or 2, characterized in that, It also includes several capacitors. Among the several resistors, resistor R15 is connected in series between the drain of P-type MOS transistor Q3 and the non-inverting input of operational amplifier U1; the non-inverting input of operational amplifier U1 is connected to one end of C1; one end of resistor R16 is connected to one end of C2 and the non-inverting input of operational amplifier U2; the other end of resistor R16, the other end of C1, the other end of C2 and the ground terminal are connected.
4. The distributed photovoltaic control circuit according to claim 1, characterized in that, A connector H1 is connected in series between the gate of the P-type MOSFET Q2 and the coil QFA_COIL of the circuit breaker. Connector H1 and the coil QFA_COIL of the circuit breaker are also connected to one end of the signal switch KEY1. The other end of the signal switch KEY1 is connected to the power supply. Connector H2 is also connected in series between the drain of the P-type MOSFET Q5 and the coil QFB_COIL of the circuit breaker.
5. The distributed photovoltaic control circuit according to claim 1, characterized in that, Of the resistors, one end of resistor R3 is connected to the power supply, and the other end is connected to the inverting input of operational amplifier U2 and one end of resistor R2; the other end of resistor R2 is connected to the ground terminal.
6. The distributed photovoltaic control circuit according to claim 2, characterized in that, The connection between resistors R12 and R13 is also connected to one end of signal switch KEY2, and the other end of signal switch KEY2 is connected to the power supply.