Power transmission line on-line power supply control system

Abstract

This invention provides an online power supply control system for transmission lines, comprising a current transformer CT1, a rectifier circuit REC1, a front-end circuit, a first switching circuit, a second switching circuit, an online power supply detection and control circuit, and a second switching circuit. The current transformer CT1 is installed on the transmission line to draw power through induction. The output terminal of the current transformer CT1 is connected to the input terminal of the rectifier circuit REC1, the output terminal of the rectifier circuit REC1 is connected to the input terminal of the front-end circuit, the output terminal of the front-end circuit is connected to the input terminal of the first switching circuit, and the output terminal of the first switching circuit supplies power to the load. The input terminal of the second switching circuit is connected to the positive terminal of a lithium battery BAT1, and the output terminal of the second switching circuit is connected to the load. The first control terminal of the online power supply detection and control circuit is connected to the control input terminal of the first switching circuit, and the second output terminal of the online detection and control circuit is connected to the control input terminal of the second switching circuit.

Description

Technical Field

[0001] This invention relates to a low-voltage DC power supply system, and more particularly to an online power supply control system for transmission lines. Background Technology

[0002] In power operation, it is often necessary to monitor the operating status of transmission lines (including overhead lines and underground cables), such as voltage, current, environmental conditions, insulator conditions, and other indicators. Various sensors, processing circuits, and network equipment are required to monitor these indicators, which necessitates low-voltage DC power supply.

[0003] In existing technologies, low-voltage DC power supply generally uses solar energy and batteries. Solar energy is greatly affected by the environment and has poor stability, while the battery life is also limited by the environment, such as temperature. Although these two methods can be combined, the problem of poor stability still exists. Therefore, people are gradually inclined to combine online power supply with batteries (generally lithium batteries with high power density). Online power supply involves inductively drawing power through a current transformer, then rectifying and filtering it to supply power to the load. The battery acts as a redundant power source. When there is a fault in the online power supply (usually overvoltage or undervoltage), the battery supplies power. When the online power supply circuit returns to normal, it supplies power to the load again. This method greatly improves the stability of low-voltage DC power supply. However, the existing technology has the problem of complex circuit structure in the switching control between the online power supply circuit and the battery power supply. It requires the use of various monitoring chips to achieve switching, which makes the cost high. If the circuit is simplified, the stability is poor and the smoothness of switching is seriously affected.

[0004] Therefore, in order to solve the above-mentioned technical problems, it is urgent to propose a new technical approach. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an online power supply control system for transmission lines, which can accurately detect whether there is overvoltage or undervoltage in the online power supply and quickly switch to lithium battery power supply when there is overvoltage or undervoltage. Moreover, it can automatically judge the status of the online power supply circuit and automatically switch to the online power supply circuit when the online power supply circuit is normal, thereby ensuring the stability of the load power supply. In addition, the circuit structure is relatively simple, requiring no complex chips, thus reducing the cost of use.

[0006] The present invention provides an online power supply control system for transmission lines, comprising a current transformer CT1, a rectifier circuit REC1, a front-end circuit, a first switching circuit, a second switching circuit, an online power supply detection and control circuit, and a second switching circuit.

[0007] The current transformer CT1 is installed in the transmission line to draw power through induction. The output terminal of the current transformer CT1 is connected to the input terminal of the rectifier circuit REC1. The output terminal of the rectifier circuit REC1 is connected to the input terminal of the front-end circuit. The output terminal of the front-end circuit is connected to the input terminal of the first switching circuit. The output terminal of the first switching circuit supplies power to the load. The input terminal of the second switching circuit is connected to the positive terminal of the lithium battery BAT1. The output terminal of the second switching circuit is connected to the load. The first control terminal of the online power supply detection and control circuit is connected to the control input terminal of the first switching circuit. The second output terminal of the online detection and control circuit is connected to the control input terminal of the second switching circuit.

[0008] Furthermore, the online detection and control circuit includes resistors R4, R5, R6, R7, R2, R3, R11, R12, R13, R10, R14, R15, R16, R17, R18, and R19; diodes D1, D2, and D3; Zener diodes ZD1 and ZD2; transistors Q2 and Q6; diode D4; an OR gate circuit U2; and a comparator U1.

[0009] One end of resistor R4 is connected to the output terminal of the front-end circuit, and the other end of resistor R4 is grounded through resistor R5. The common connection point between resistor R4 and resistor R5 is connected to the negative terminal of Zener diode ZD2. The positive terminal of Zener diode ZD2 is connected to the positive terminal of diode D1 through resistor R7. The negative terminal of diode D1 is connected to the control input terminal of the first switching circuit as the first control terminal of the online detection and control circuit.

[0010] The negative terminal of Zener diode ZD1 is connected to the common connection point between resistors R4 and R5. The positive terminal of Zener diode ZD1 is grounded through resistors R2 and R3 in series. The common connection point of resistors R2 and R3 is connected to the positive terminal of transistor Q6. The emitter of transistor Q6 is connected to the positive terminal of lithium battery BAT1 through resistor R18. The base of transistor Q6 is connected to the positive terminal of diode D2 through resistor R19. The negative terminal of diode D2 is connected to the negative terminal of diode D1.

[0011] The positive terminal of diode D3 is connected to the collector of transistor Q6, and the negative terminal of diode D3 is connected to one end of resistor R13. The other end of resistor R13 serves as the second output terminal of the online detection and control circuit and is connected to the control input terminal of the second switching circuit.

[0012] The non-inverting input of comparator U1 is connected to the positive terminal of lithium battery BAT1 through resistor R17. The non-inverting input of comparator U1 is grounded through capacitor C3 and resistor R16 connected in series. The power supply terminal of comparator U1 is connected to the positive terminal of lithium battery BAT1 through resistor R15. The output terminal of comparator U1 is connected to the base of transistor Q2 through resistor R10. The transmitter of transistor Q2 is grounded. The collector of transistor Q2 is connected to the output terminal of the front-end circuit through resistor R6.

[0013] The positive terminal of diode D1 is connected to the positive terminal of diode D4, the negative terminal of diode D4 is connected to the negative terminal of diode D3, the first input terminal of OR gate circuit U2 is connected to the base of transistor Q6, the second input terminal of OR gate circuit U2 is connected to the positive terminal of diode D4, and the output terminal of OR gate circuit U2 is connected to the inverting input of comparator U1 through resistor R14.

[0014] Among them: transistor Q6 is a P transistor, and the forward voltage of Zener diode ZD2 is greater than the forward voltage of Zener diode ZD1.

[0015] Furthermore, the first switching circuit includes an NMOS transistor Q1, a resistor R8, a resistor R9, a capacitor C2, and a thyristor Q3;

[0016] The drain of NMOS transistor Q1 is connected to the input terminal of the front-end circuit as the power input terminal of the first switching circuit. The source of NMOS transistor Q1 is connected to the load as the power output terminal of the first switching circuit. The drain of NMOS transistor Q1 is connected to the gate of NMOS transistor Q1 through resistor R8. The gate of NMOS transistor Q1 is grounded through resistor R9. The gate of NMOS transistor Q1 is grounded through capacitor C2. The positive terminal of thyristor Q3 is connected to the gate of NMOS transistor Q1. The negative terminal of thyristor Q1 is grounded. The control terminal of thyristor Q1 is connected to the negative terminal of diode D1 as the control input terminal of the first switching circuit.

[0017] Furthermore, the second switching circuit includes a PMOS transistor Q4, a resistor R11, a resistor R12, and a transistor Q5;

[0018] The source of PMOS transistor Q4 is connected to the lithium battery BAT1 as the input terminal of the second switching circuit, and the drain of PMOS transistor Q4 is connected to the load as the output terminal of the second switching circuit. The source of PMOS transistor Q4 is connected to the gate of PMOS transistor Q4 through resistor R11, and the gate of PMOS transistor Q4 is connected to the collector of transistor Q5 through resistor R12. The transmitter of transistor Q5 is grounded, and the base of transistor Q5 is connected to resistor R13 as the control input terminal of the second switching circuit.

[0019] Furthermore, the front-end circuit includes a varistor VR1, a resistor R1, and a capacitor C1;

[0020] One end of resistor R1 is grounded through varistor VR1, and the other end of resistor R1 serves as the output terminal of the front-end circuit. The common connection point of resistor R1 and varistor VR1 is grounded through capacitor C1, and the common connection point of resistor R1 and varistor VR1 serves as the input terminal of the front-end circuit connected to the output terminal of rectifier circuit REC1.

[0021] The beneficial effects of this invention are as follows: This invention can accurately detect whether there is overvoltage or undervoltage in the online power supply and quickly switch to lithium battery power supply when there is overvoltage or undervoltage. It can also automatically judge the status of the online power supply circuit and automatically switch to the online power supply circuit when the online power supply circuit is normal, thereby ensuring the stability of the load power supply. Moreover, the circuit structure is relatively simple, requiring no complex chips, thus reducing the cost of use. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0023] Figure 1 This is the circuit schematic diagram of the present invention. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings:

[0025] The present invention provides an online power supply control system for transmission lines, comprising a current transformer CT1, a rectifier circuit REC1, a front-end circuit, a first switching circuit, a second switching circuit, an online power supply detection and control circuit, and a second switching circuit.

[0026] The current transformer CT1 is installed in the transmission line for inductive power extraction. The output terminal of the current transformer CT1 is connected to the input terminal of the rectifier circuit REC1. The output terminal of the rectifier circuit REC1 is connected to the input terminal of the front-end circuit. The output terminal of the front-end circuit is connected to the input terminal of the first switching circuit. The output terminal of the first switching circuit supplies power to the load. The input terminal of the second switching circuit is connected to the positive terminal of the lithium battery BAT1. The output terminal of the second switching circuit is connected to the load. The first control terminal of the online power supply detection and control circuit is connected to the control input terminal of the first switching circuit. The second output terminal of the online detection and control circuit is connected to the control input terminal of the second switching circuit. With the above structure, it is possible to accurately detect whether there is overvoltage or undervoltage in the online power extraction and quickly switch to the lithium battery power supply state when there is overvoltage or undervoltage. Moreover, it can automatically judge the status of the online power extraction circuit and automatically switch to the online power supply circuit when the online power extraction circuit is normal, thereby ensuring the stability of the load power supply. In addition, the circuit structure is relatively simple, requiring no complex chips, reducing the cost of use.

[0027] Specifically, the online detection and control circuit includes resistors R4, R5, R6, R7, R2, R3, R11, R12, R13, R10, R14, R15, R16, R17, R18, and R19; diodes D1, D2, and D3; Zener diodes ZD1 and ZD2; transistors Q2 and Q6; diode D4; an OR gate circuit U2; and a comparator U1.

[0028] One end of resistor R4 is connected to the output terminal of the front-end circuit, and the other end of resistor R4 is grounded through resistor R5. The common connection point between resistor R4 and resistor R5 is connected to the negative terminal of Zener diode ZD2. The positive terminal of Zener diode ZD2 is connected to the positive terminal of diode D1 through resistor R7. The negative terminal of diode D1 is connected to the control input terminal of the first switching circuit as the first control terminal of the online detection and control circuit.

[0029] The negative terminal of Zener diode ZD1 is connected to the common connection point between resistors R4 and R5. The positive terminal of Zener diode ZD1 is grounded through resistors R2 and R3 in series. The common connection point of resistors R2 and R3 is connected to the positive terminal of transistor Q6. The emitter of transistor Q6 is connected to the positive terminal of lithium battery BAT1 through resistor R18. The base of transistor Q6 is connected to the positive terminal of diode D2 through resistor R19. The negative terminal of diode D2 is connected to the negative terminal of diode D1.

[0030] The positive terminal of diode D3 is connected to the collector of transistor Q6, and the negative terminal of diode D3 is connected to one end of resistor R13. The other end of resistor R13 serves as the second output terminal of the online detection and control circuit and is connected to the control input terminal of the second switching circuit.

[0031] The non-inverting input of comparator U1 is connected to the positive terminal of lithium battery BAT1 through resistor R17. The non-inverting input of comparator U1 is grounded through capacitor C3 and resistor R16 connected in series. The power supply terminal of comparator U1 is connected to the positive terminal of lithium battery BAT1 through resistor R15. The output terminal of comparator U1 is connected to the base of transistor Q2 through resistor R10. The transmitter of transistor Q2 is grounded. The collector of transistor Q2 is connected to the output terminal of the front-end circuit through resistor R6.

[0032] The positive terminal of diode D1 is connected to the positive terminal of diode D4, the negative terminal of diode D4 is connected to the negative terminal of diode D3, the first input terminal of OR gate circuit U2 is connected to the base of transistor Q6, the second input terminal of OR gate circuit U2 is connected to the positive terminal of diode D4, and the output terminal of OR gate circuit U2 is connected to the inverting input of comparator U1 through resistor R14.

[0033] Among them: transistor Q6 is a P transistor, and the forward voltage of Zener diode ZD2 is greater than the forward voltage of Zener diode ZD1.

[0034] The first switching circuit includes an NMOS transistor Q1, a resistor R8, a resistor R9, a capacitor C2, and a silicon controlled rectifier Q3;

[0035] The drain of NMOS transistor Q1 is connected to the input terminal of the front-end circuit as the power input terminal of the first switching circuit. The source of NMOS transistor Q1 is connected to the load as the power output terminal of the first switching circuit. The drain of NMOS transistor Q1 is connected to the gate of NMOS transistor Q1 through resistor R8. The gate of NMOS transistor Q1 is grounded through resistor R9. The gate of NMOS transistor Q1 is grounded through capacitor C2. The positive terminal of thyristor Q3 is connected to the gate of NMOS transistor Q1. The negative terminal of thyristor Q1 is grounded. The control terminal of thyristor Q1 is connected to the negative terminal of diode D1 as the control input terminal of the first switching circuit.

[0036] The second switching circuit includes a PMOS transistor Q4, a resistor R11, a resistor R12, and a transistor Q5;

[0037] The source of PMOS transistor Q4 is connected to the lithium battery BAT1 as the input terminal of the second switching circuit, and the drain of PMOS transistor Q4 is connected to the load as the output terminal of the second switching circuit. The source of PMOS transistor Q4 is connected to the gate of PMOS transistor Q4 through resistor R11, and the gate of PMOS transistor Q4 is connected to the collector of transistor Q5 through resistor R12. The transmitter of transistor Q5 is grounded, and the base of transistor Q5 is connected to resistor R13 as the control input terminal of the second switching circuit.

[0038] The front-end circuit includes a varistor VR1, a resistor R1, and a capacitor C1;

[0039] One end of resistor R1 is grounded through varistor VR1, and the other end of resistor R1 serves as the output terminal of the front-end circuit. The common connection point of resistor R1 and varistor VR1 is grounded through capacitor C1, and the common connection point of resistor R1 and varistor VR1 serves as the input terminal of the front-end circuit connected to the output terminal of rectifier circuit REC1.

[0040] The principles of this invention will be further explained in detail below:

[0041] like Figure 1 As shown, the front-end circuit consists of resistor R1, VR1 and capacitor C1. Among them, varistor VR1 is used for clamping protection, capacitor C1 is used for filtering and peak clipping, and resistor R1 is used for voltage limiting and current limiting.

[0042] Resistors R2 and R3, along with Zener diode ZD1, form an undervoltage detection circuit. Zener diode ZD2 and resistor R7 form an overvoltage detection circuit. When the circuit is overvoltaged, Zener diode ZD2 conducts, outputting a high level to the thyristor through resistor R7. At this time, Zener diode ZD1 conducts, and the base voltage of transistor Q6 is greater than the transmitter voltage, causing it to cut off. When the circuit is undervoltaged, Zener diode ZD2 and Zener diode ZD1 both cut off, creating a low level between resistors R2 and R3. Transistor Q6 then conducts, outputting a high level to the thyristor Q3 through resistor R19. Therefore, it can be seen from the above that regardless of whether there is overvoltage or undervoltage, the control electrode of transistor Q3 can always obtain a high level to trigger the thyristor Q3 to conduct. Zener diode ZD3 is used to protect Zener diode ZD1 and transistor Q6.

[0043] In the first switching circuit, the switching transistor is an NMOS transistor. When the voltage is normal, the gate of NMOS transistor Q1 is divided by resistors R8 and R9 to provide voltage, causing NMOS transistor Q1 to conduct. Thus, the online power supply circuit, namely the circuit consisting of current transformer CT1, rectifier circuit REC1, front-end circuit and the first switching circuit, supplies power to the load. At this time, thyristor Q3 is off. This is because thyristor Q3 has a triggering characteristic. Thyristor Q3 will only conduct when there is no triggering signal at its control electrode. When there is undervoltage or overvoltage, a high-level trigger signal is input to the control electrode of thyristor Q3, thyristor Q3 conducts, the gate of NMOS transistor Q1 is de-energized and cut off, and the first switching circuit stops supplying power. At this time, whether it is undervoltage or overvoltage, a high level will be output to transistor Q5, triggering transistor Q5 to conduct. Since the switching transistor in the second switching circuit is a PMOS transistor, PMOS transistor Q4 will only conduct when transistor Q5 conducts. At this time, the lithium battery power supply state is entered.

[0044] When the voltage returns to normal, transistor Q6 returns to a high level, while the anode of diode D4 returns to a low level. At this time, the OR gate U2 outputs a high level, making the voltage at the inverting input of the comparator greater than the reference voltage at the non-inverting input. Comparator U1 outputs a high level, causing transistor Q2 to conduct. After transistor Q2 conducts, the negative potential of thyristor Q3 is greater than its positive potential when transistor Q2 is conducting, causing thyristor Q3 to be reverse-biased and cut off. At this time, Q1 resumes conduction. Since the voltage returns to normal, transistor Q6 returns to a low level, while Zener diode ZD2 returns to cut off, and the anode of diode D4 returns to a low level. At this time, the OR gate outputs a low level, comparator U1 outputs a low level, and transistor Q5 and PMOS transistor Q4 are cut off. The lithium battery's power supply to the load is interrupted, completing the switching from lithium battery to online power supply circuit.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An online power supply control system for transmission lines, characterized in that: It includes a current transformer CT1, a rectifier circuit REC1, a front-end circuit, a first switching circuit, a second switching circuit, an online detection and control circuit, and a second switching circuit; The current transformer CT1 is installed in the transmission line to draw power through induction. The output terminal of the current transformer CT1 is connected to the input terminal of the rectifier circuit REC1. The output terminal of the rectifier circuit REC1 is connected to the input terminal of the front-end circuit. The output terminal of the front-end circuit is connected to the input terminal of the first switching circuit. The output terminal of the first switching circuit supplies power to the load. The input terminal of the second switching circuit is connected to the positive terminal of the lithium battery BAT1. The output terminal of the second switching circuit is connected to the load. The first control terminal of the online detection and control circuit is connected to the control input terminal of the first switching circuit. The second output terminal of the online detection and control circuit is connected to the control input terminal of the second switching circuit. The online detection and control circuit includes resistors R4, R5, R6, R7, R2, R3, R13, R10, R14, R15, R16, R17, R18, and R19; diodes D1, D2, and D3; Zener diodes ZD1 and ZD2; transistors Q2 and Q6; diode D4; an OR gate circuit U2; and a comparator U1. One end of resistor R4 is connected to the output terminal of the front-end circuit, and the other end of resistor R4 is grounded through resistor R5. The common connection point between resistor R4 and resistor R5 is connected to the negative terminal of Zener diode ZD2. The positive terminal of Zener diode ZD2 is connected to the positive terminal of diode D1 through resistor R7. The negative terminal of diode D1 is connected to the control input terminal of the first switching circuit as the first control terminal of the online detection and control circuit. The negative terminal of Zener diode ZD1 is connected to the common connection point between resistors R4 and R5. The positive terminal of Zener diode ZD1 is grounded through resistors R2 and R3 in series. The common connection point of resistors R2 and R3 is connected to the base of transistor Q6. The emitter of transistor Q6 is connected to the positive terminal of lithium battery BAT1 through resistor R18. The base of transistor Q6 is connected to the positive terminal of diode D2 through resistor R19. The negative terminal of diode D2 is connected to the negative terminal of diode D1. The positive terminal of diode D3 is connected to the collector of transistor Q6, and the negative terminal of diode D3 is connected to one end of resistor R13. The other end of resistor R13 serves as the second output terminal of the online detection and control circuit and is connected to the control input terminal of the second switching circuit. The non-inverting input of comparator U1 is connected to the positive terminal of lithium battery BAT1 through resistor R17. The non-inverting input of comparator U1 is grounded through parallel capacitor C3 and resistor R16. The power supply terminal of comparator U1 is connected to the positive terminal of lithium battery BAT1 through resistor R15. The output terminal of comparator U1 is connected to the base of transistor Q2 through resistor R10. The emitter of transistor Q2 is grounded. The collector of transistor Q2 is connected to the output terminal of the front-end circuit through resistor R6. The positive terminal of diode D1 is connected to the positive terminal of diode D4, the negative terminal of diode D4 is connected to the negative terminal of diode D3, the first input terminal of OR gate circuit U2 is connected to the base of transistor Q6, the second input terminal of OR gate circuit U2 is connected to the positive terminal of diode D4, and the output terminal of OR gate circuit U2 is connected to the inverting input of comparator U1 through resistor R14. Among them: transistor Q6 is a P transistor, and the forward voltage of Zener diode ZD2 is greater than the forward voltage of Zener diode ZD1; The first switching circuit includes an NMOS transistor Q1, a resistor R8, a resistor R9, a capacitor C2, and a silicon controlled rectifier Q3; The drain of NMOS transistor Q1 is connected to the output of the front-end circuit as the power input terminal of the first switching circuit. The source of NMOS transistor Q1 is connected to the load as the power output terminal of the first switching circuit. The drain of NMOS transistor Q1 is connected to the gate of NMOS transistor Q1 through resistor R8. The gate of NMOS transistor Q1 is grounded through resistor R9. The gate of NMOS transistor Q1 is grounded through capacitor C2. The positive terminal of thyristor Q3 is connected to the gate of NMOS transistor Q1. The negative terminal of thyristor Q1 is grounded. The control terminal of thyristor Q1 is connected to the negative terminal of diode D1 as the control input terminal of the first switching circuit. The second switching circuit includes a PMOS transistor Q4, a resistor R11, a resistor R12, and a transistor Q5; The source of PMOS transistor Q4 is connected to the lithium battery BAT1 as the input terminal of the second switching circuit. The drain of PMOS transistor Q4 is connected to the load as the output terminal of the second switching circuit. The source of PMOS transistor Q4 is connected to the gate of PMOS transistor Q4 through resistor R11. The gate of PMOS transistor Q4 is connected to the collector of transistor Q5 through resistor R12. The emitter of transistor Q5 is grounded. The base of transistor Q5 is connected to resistor R13 as the control input terminal of the second switching circuit.

2. The online power supply control system for transmission lines according to claim 1, characterized in that: The front-end circuit includes a varistor VR1, a resistor R1, and a capacitor C1; One end of resistor R1 is grounded through varistor VR1, and the other end of resistor R1 serves as the output terminal of the front-end circuit. The common connection point of resistor R1 and varistor VR1 is grounded through capacitor C1, and the common connection point of resistor R1 and varistor VR1 serves as the input terminal of the front-end circuit connected to the output terminal of rectifier circuit REC1.

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