A multi-source composite power management circuit and system for monitoring power transmission and distribution lines

Abstract

This invention discloses a multi-source composite power management circuit for monitoring power transmission and distribution lines, including a multi-source input interface comprising a piezoelectric input terminal, a CT input terminal, and a solar input terminal; a DC bus; an energy storage unit connected to the DC bus; a piezoelectric energy processing branch connected between the piezoelectric input terminal and the DC bus, comprising a rectifier unit, an intermediate energy storage capacitor, a voltage threshold control switch, and a first voltage regulator unit connected in series; the voltage threshold control switch is configured to close when the voltage across the intermediate energy storage capacitor reaches a preset conduction threshold and open when the voltage is below a preset turn-off threshold; and a self-powered feedback loop, whose input terminal is connected to the energy storage unit and whose output terminal is connected to the power supply pin of the voltage threshold control switch. This effectively solves the impedance mismatch problem between high-resistance piezoelectric components and the load, significantly improving energy conversion efficiency under weak vibrations.

Description

Technical Field

[0001] This invention relates to the technical field of power monitoring, and in particular to a multi-source composite power management circuit and system for monitoring power transmission and distribution lines. Background Technology

[0002] With the construction of smart grids, the number of online monitoring devices (such as dynamic capacity expansion systems and icing monitoring devices) installed on overhead transmission and distribution lines is increasing. These devices usually operate in high-voltage outdoor environments and cannot be powered by low-voltage mains power. Therefore, obtaining a stable and reliable power supply has become a key bottleneck restricting their large-scale application.

[0003] Currently, the main energy harvesting methods for transmission lines include solar photovoltaic energy harvesting and current transformer (CT) induction energy harvesting.

[0004] Solar energy harvesting: is greatly affected by weather, seasons and day-night cycles, and the surface of photovoltaic panels is prone to dust accumulation, resulting in poor power supply stability and inability to work around the clock.

[0005] CT induction power harvesting: heavily reliant on line load current. When the line is operating under low current (e.g., below 5A or 10A), the CT core cannot induct enough energy, creating a "power harvesting dead zone"; while under high current or short-circuit faults, there is a risk of core saturation heating or even circuit burnout.

[0006] To eliminate power supply blind spots, piezoelectric energy harvesting technology, which utilizes the vibration of alternating magnetic fields around transmission lines, has become an effective supplementary method. However, applying piezoelectric energy harvesting technology to practical circuits faces significant electrical challenges: Severe impedance mismatch: Piezoelectric materials (such as PZT or MFC) are inherently capacitive high-impedance sources, with internal resistance typically ranging from 150kΩ to 200kΩ. If they are directly connected to standard rectifier filter circuits or low-impedance loads, severe impedance mismatch will occur, resulting in the majority of energy loss due to the internal resistance of the power supply, leading to extremely low output power.

[0007] The energy is weak and difficult to collect: piezoelectric elements output high-voltage, low-current alternating current, which fluctuates greatly with the current in the conductor. Traditional continuous charging methods cannot effectively accumulate this weak and intermittent energy to drive the downstream circuitry.

[0008] Multi-source coordination challenges: When integrating three power sources with vastly different characteristics—piezoelectric (high-voltage micro-current AC), CT (low-voltage high-current AC), and solar energy (fluctuating DC)—into a single system, how to design a reasonable topology that ensures each branch does not interfere with the others and prevents energy backflow, while simultaneously achieving efficient energy convergence and unified management, is a pressing technical challenge that needs to be addressed. Summary of the Invention

[0009] Therefore, the technical problem to be solved by this invention is: the high internal resistance characteristics of piezoelectric energy harvesting technology in practical applications lead to severe impedance mismatch, making it difficult to effectively accumulate and extract weak energy, and the technical difficulty of achieving efficient coordinated current convergence of multi-source heterogeneous energy (piezoelectric high voltage AC, CT high current AC, photovoltaic DC).

[0010] The above-mentioned technical problems are solved by the following technical solution: The present invention proposes a multi-source composite power management circuit for monitoring power transmission and distribution lines, including a multi-source input interface, including a piezoelectric input terminal, a CT input terminal and a solar input terminal; a DC bus; and an energy storage unit connected to the DC bus. A piezoelectric energy processing branch, connected between the piezoelectric input terminal and the DC bus, includes a rectifier unit, an intermediate energy storage capacitor, a voltage threshold control switch, and a first voltage regulator unit connected in series. The voltage threshold control switch is configured to close when the voltage across the intermediate energy storage capacitor reaches a preset conduction threshold and open when the voltage is lower than a preset shutdown threshold. A self-powered feedback loop has its input terminal connected to the energy storage unit and its output terminal connected to the power supply pin of the voltage threshold control switch.

[0011] In a preferred embodiment of the multi-source composite power management circuit for power transmission and distribution line monitoring described in this invention: the piezoelectric energy processing branch further includes an input protection unit, which is disposed between the piezoelectric input terminal and the rectifier unit.

[0012] In a preferred embodiment of the multi-source composite power management circuit for power transmission and distribution line monitoring described in this invention: it further includes a CT energy processing branch connected between the CT input terminal and the DC bus; the CT energy processing branch includes an AC protection unit, a bridge rectifier unit and a second voltage regulator unit connected in sequence; the output terminal of the second voltage regulator unit is connected to the DC bus through an anti-backflow diode.

[0013] In a preferred embodiment of the multi-source composite power management circuit for power transmission and distribution line monitoring described in this invention: it further includes a solar energy processing branch connected between the solar energy input terminal and the DC bus; the solar energy processing branch includes a branch protection unit and a third voltage regulator unit, the output terminal of the third voltage regulator unit being connected to the DC bus via an anti-backflow diode.

[0014] In a preferred embodiment of the multi-source composite power management circuit for power transmission and distribution line monitoring described in this invention: the output voltage values ​​of the first voltage regulator unit, the second voltage regulator unit, and the third voltage regulator unit are equal.

[0015] In a preferred embodiment of the multi-source composite power management circuit for power transmission and distribution line monitoring described in this invention: the self-powered feedback loop includes an auxiliary power module, which converts the voltage of the energy storage unit into a constant voltage and provides it to the voltage threshold control switch.

[0016] In a preferred embodiment of the multi-source composite power management circuit for power transmission and distribution line monitoring described in this invention: it further includes a load power supply branch connected to the output terminal of the energy storage unit; the load power supply branch includes a battery undervoltage protection switch and an output voltage regulator module connected in sequence.

[0017] In a preferred embodiment of the multi-source composite power management circuit for power transmission and distribution line monitoring described in this invention: the voltage threshold control switch is a low-power step-down DC-DC converter or an analog switch circuit.

[0018] In a preferred embodiment of the multi-source composite power management circuit for power transmission and distribution line monitoring described in this invention: a lithium battery charging management module is provided between the DC bus and the energy storage unit.

[0019] To address the issue of poor power supply reliability of online monitoring equipment for power transmission and distribution lines under harsh environments or low loads due to a single power supply method, this invention also proposes an online monitoring system for power transmission and distribution lines, comprising a multi-source composite power management circuit; and a piezoelectric energy harvester, a current transformer, and a solar panel respectively connected to the multi-source input interface.

[0020] The beneficial effects of this invention are as follows: By designing a piezoelectric energy processing branch that includes a voltage threshold control switch, this invention utilizes an intermediate energy storage capacitor to accumulate weak current and release it instantaneously when the threshold is reached, thus achieving intermittent extraction of piezoelectric energy. This effectively solves the impedance mismatch problem between high-resistance piezoelectric components and the load, significantly improving energy conversion efficiency under weak vibration. Simultaneously, this invention constructs a multi-source composite power supply topology integrating piezoelectric, CT, and solar energy. Through voltage stabilization and backflow prevention designs in each branch, it achieves efficient convergence of heterogeneous electrical energy. By utilizing the complementary characteristics of different energy sources, it eliminates the "energy extraction dead zone" of a single power supply method, ensuring all-weather operation of the monitoring equipment. Furthermore, through a self-powered feedback loop design, this invention utilizes stored electrical energy to drive the internal control chip in reverse, achieving self-sustaining operation of the circuit system and significantly enhancing the device's start-up capability and reliability in harsh environments such as no light and low load. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein: Figure 1 A block diagram of the overall circuit design of a multi-source composite power management circuit for monitoring power transmission and distribution lines is shown. Figure 2 A schematic diagram of a piezoelectric energy processing branch circuit for a multi-source composite power management circuit used for power transmission and distribution line monitoring is shown. Figure 3 A schematic diagram of a CT energy processing branch circuit for a multi-source composite power management circuit used for power transmission and distribution line monitoring is shown. Figure 4 A schematic diagram of the solar processing branch circuit of a multi-source composite power management circuit for monitoring power transmission and distribution lines is shown. Figure 5 A schematic diagram of a self-powered feedback loop for a multi-source composite power management circuit used for monitoring power transmission and distribution lines is shown. Figure 6 A schematic diagram of a self-powered feedback loop for a multi-source composite power management circuit used for monitoring power transmission and distribution lines is shown. Figure 7 A schematic diagram of a self-powered feedback loop for a multi-source composite power management circuit used for monitoring power transmission and distribution lines is shown. Figure 8 A lithium battery discharge circuit diagram is shown for a multi-source composite power management circuit for monitoring power transmission and distribution lines. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0023] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0024] Example 1 Reference Figure 1-7This embodiment provides a multi-source composite power management circuit for monitoring power transmission and distribution lines, including a multi-source input interface 1, comprising a piezoelectric input terminal 11, a CT input terminal 12, and a solar input terminal 13; a DC bus 2; an energy storage unit 3 connected to the DC bus 2; a piezoelectric energy processing branch 4 connected between the piezoelectric input terminal 11 and the DC bus 2, comprising a rectifier unit 41, an intermediate energy storage capacitor 42, a voltage threshold control switch 43, and a first voltage regulator unit 44 connected in series; the voltage threshold control switch 43 is configured to close when the voltage across the intermediate energy storage capacitor 42 reaches a preset conduction threshold and open when the voltage is lower than a preset shutdown threshold; and a self-powered feedback loop 5, whose input terminal is connected to the energy storage unit 3 and whose output terminal is connected to the power pin of the voltage threshold control switch 43. Note that piezoelectric materials such as PZT or MFC have extremely high internal resistance of approximately 150kΩ~200kΩ, and direct connection to the load can lead to severe impedance mismatch. This embodiment utilizes an intermittent "accumulation-release" control strategy: during the switch-off period, a weak piezoelectric current charges the intermediate energy storage capacitor 42, and the voltage gradually increases; when the voltage reaches the conduction threshold, such as the UVLO rising threshold, the switch closes instantaneously, releasing the accumulated high-voltage energy to the first voltage regulator unit 44, such as the step-down circuit. This method achieves effective matching between the high-impedance source and the low-impedance load, significantly improving energy utilization under weak vibration environments.

[0025] The piezoelectric energy processing branch 4 also includes an input protection unit 45, located between the piezoelectric input terminal 11 and the rectifier unit 41. Because the vibration amplitude of the transmission line is uncontrollable, the piezoelectric element may generate peak voltages as high as 100 volts under strong winds or swaying conditions. The input protection unit 45, composed of a bidirectional TVS diode or Zener diode, clamps the input voltage within a safe range, such as 20V, to prevent damage to the subsequent rectifier bridge and capacitors due to overvoltage.

[0026] The CT energy processing branch 6 is connected between the CT input terminal 12 and the DC bus 2. The CT energy processing branch 6 includes an AC protection unit 61, a bridge rectifier unit 6241, and a second voltage regulator unit 63 connected in sequence. The output terminal of the second voltage regulator unit 63 is connected to the DC bus 2 via an anti-backflow diode. The CT current transformer primarily extracts energy for high-current circuit conditions. The AC protection unit 61 absorbs surge currents induced during short circuits or lightning strikes. The rectified pulsating DC power is stabilized by the second voltage regulator unit 63 before being output. The anti-backflow diode, such as a Schottky diode, prevents the voltage on the DC bus 2 from potentially flowing back to the CT coil from solar energy or batteries, causing energy loss or circuit failure.

[0027] A solar energy processing branch 7 is connected between the solar energy input terminal 13 and the DC bus 2. The solar energy processing branch 7 includes a branch protection unit and a third voltage regulator unit 72. The output of the third voltage regulator unit 72 is connected to the DC bus 2 via an anti-backflow diode. The output voltage of the solar panel fluctuates significantly with light intensity. The third voltage regulator unit 72 clamps its output voltage to the DC bus voltage level to prevent overvoltage damage to the battery. The series-connected anti-backflow diode prevents reverse leakage of electrical energy from the energy storage unit 3 to the solar panel at night or on cloudy days without sunlight, thus preventing the "dark current" effect.

[0028] The output voltages of the first voltage regulator unit 44, the second voltage regulator unit 63, and the third voltage regulator unit 72 are equal. To ensure safe consolidation of multiple energy sources, the output voltages of the three branches are set to a unified DC bus voltage, such as 5V. This allows all energy sources—piezoelectric, current transformer (CT), or solar energy—to supply power to the energy storage unit 3 via the DC bus 2, regardless of whether they are operating. The branch with the higher voltage automatically assumes the primary power supply role, achieving multi-source complementarity.

[0029] The self-powered feedback loop 5 includes an auxiliary power module 51, which converts the voltage of the energy storage unit 3 into a constant voltage and supplies it to the voltage threshold control switch 43. The voltage threshold control switch 43, such as the integrated chip LTC3588 or an active analog switch, requires a small quiescent current to operate. In extreme environments with no light and extremely low line current, relying solely on piezoelectric operation, to ensure the switch can be properly "wake up" and perform its actions, the energy stored in the lithium battery of the energy storage unit 3 is stepped down to 3V by the auxiliary power module 51 and fed back to the control chip. This constitutes a self-sustaining closed loop, greatly enhancing the robustness of the circuit.

[0030] A load power supply branch 8 is connected to the output terminal of the energy storage unit 3. The load power supply branch 8 includes a battery undervoltage protection switch and an output voltage regulator module connected in sequence. The battery undervoltage protection switch monitors the lithium battery voltage and automatically disconnects the load circuit when the voltage falls below an over-discharge threshold, such as 2.5V, to prevent battery damage from over-discharge. The output voltage regulator module converts the battery voltage to a standard 3.3V DC voltage, providing a stable operating power supply for downstream sensors, microprocessors, and wireless communication modules.

[0031] The voltage threshold control switch 43 is a low-power buck DC-DC converter or an analog switch circuit. The use of a low-power buck DC-DC converter (Buck Converter) compared to a linear regulator (LDO) allows for more efficient conversion of accumulated high voltages (e.g., 10V-20V) to low voltages (e.g., 3.3V-5V), reducing heat loss during conversion and further improving system efficiency.

[0032] A lithium battery charging management module 9 is provided between the DC bus 2 and the energy storage unit 3. This module is responsible for constant current / constant voltage CC / CV charging control of the energy storage unit 3 (e.g., a polymer lithium battery) to prevent overcharging and extend battery life. Simultaneously, this module acts as an energy buffer, smoothing out instability in the front-end input source.

[0033] Example 2 This embodiment provides an online monitoring system for power transmission and distribution lines, including a multi-source composite power management circuit; and a piezoelectric energy harvester, a current transformer, and a solar panel respectively connected to the multi-source input interface 1. The system physically integrates three energy harvesting methods, utilizing the complementary environmental characteristics of different energy sources to eliminate power supply blind spots: during the day when there is sufficient sunlight, the solar panel is the main power source; when the line load current is large, the current transformer (CT) induction energy harvesting is the main power source; and at night, on cloudy or rainy days, and when the line is under low load (low current), the piezoelectric energy harvester installed on the conductor uses the energy generated by the vibration of the conductor in the wind or electromagnetic force to power the system. This design ensures that the online monitoring equipment can obtain a continuous and stable power supply under all weather conditions and operating conditions, solving the problem of poor reliability of a single energy harvesting method.

[0034] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A multi-source composite power management circuit for monitoring power transmission and distribution lines, characterized in that: It includes a multi-source input interface (1), including a piezoelectric input terminal (11), a CT input terminal (12), and a solar energy input terminal (13). DC busbar (2); Energy storage unit (3) is connected to the DC bus (2); The piezoelectric energy processing branch (4) is connected between the piezoelectric input terminal (11) and the DC bus (2), and includes a rectifier unit (41), an intermediate energy storage capacitor (42), a voltage threshold control switch (43) and a first voltage regulator unit (44) connected in series. The voltage threshold control switch (43) is configured to close when the voltage across the intermediate energy storage capacitor (42) reaches a preset conduction threshold and open when the voltage is lower than a preset turn-off threshold. The self-powered feedback loop (5) has its input end connected to the energy storage unit (3) and its output end connected to the power supply pin of the voltage threshold control switch (43).

2. The multi-source composite power management circuit for power transmission and distribution line monitoring according to claim 1, characterized in that: The piezoelectric energy processing branch (4) also includes an input protection unit (45), which is located between the piezoelectric input terminal (11) and the rectifier unit (41).

3. The multi-source composite power management circuit for power transmission and distribution line monitoring according to claim 1, characterized in that: It also includes a CT energy processing branch (6), which is connected between the CT input terminal (12) and the DC bus (2); The CT energy processing branch (6) includes an AC protection unit (61), a bridge rectifier unit (62) (41) and a second voltage regulator unit (63) connected in sequence. The output terminal of the second voltage regulator unit (63) is connected to the DC bus (2) through an anti-backflow diode.

4. The multi-source composite power management circuit for monitoring power transmission and distribution lines according to claim 3, characterized in that: It also includes a solar energy processing branch (7), which is connected between the solar energy input terminal (13) and the DC bus (2); The solar energy processing branch (7) includes a branch protection unit and a third voltage regulator unit (72). The output of the third voltage regulator unit (72) is connected to the DC busbar (2) through an anti-backflow diode.

5. The multi-source composite power management circuit for power transmission and distribution line monitoring according to claim 1, characterized in that: The output voltage values ​​of the first voltage regulator unit (44), the second voltage regulator unit (63), and the third voltage regulator unit (72) are equal.

6. The multi-source composite power management circuit for monitoring power transmission and distribution lines according to claim 1, characterized in that: The self-powered feedback loop (5) includes an auxiliary power module (51), which converts the voltage of the energy storage unit (3) into a constant voltage and provides it to the voltage threshold control switch (43).

7. The multi-source composite power management circuit for monitoring power transmission and distribution lines according to claim 1, characterized in that: It also includes a load power supply branch (8), which is connected to the output end of the energy storage unit (3); the load power supply branch (8) includes a battery undervoltage protection switch and an output voltage regulator module connected in sequence.

8. The multi-source composite power management circuit for power transmission and distribution line monitoring according to claim 1, characterized in that: The voltage threshold control switch (43) is a low-power step-down DC-DC converter or an analog switch circuit.

9. The multi-source composite power management circuit for monitoring power transmission and distribution lines according to claim 1, characterized in that: A lithium battery charging management module (9) is provided between the DC busbar (2) and the energy storage unit (3).

10. An online monitoring system for power transmission and distribution lines, characterized in that, include: The multi-source composite power management circuit as described in any one of claims 1 to 9; And a piezoelectric energy harvester, a current transformer and a solar panel respectively connected to the multi-source input interface (1).

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