A power taking device, method and on-line monitoring terminal of a high voltage direct current transmission line

Abstract

This invention discloses an energy harvesting device and method for high-voltage direct current (HVDC) transmission lines. The device includes: a resistive-capacitive voltage divider energy harvesting module, an MPPT impedance matching module, and a power conversion module. The resistive-capacitive voltage divider energy harvesting module is used to connect to the HVDC transmission line and output a high-voltage direct current (HVDC) signal. The MPPT impedance matching module is used to adjust the equivalent input impedance of the power conversion module according to the HVDC signal, so that the equivalent input impedance matches the impedance of the resistive-capacitive voltage divider energy harvesting module. The power conversion module is used to convert the HVDC signal into low-voltage direct current based on the current equivalent input impedance. This invention solves the technical problems of low power supply efficiency for sensors and inability to provide a continuous and stable power supply for online monitoring terminals of HVDC transmission lines in existing high-voltage DC circuits.

Description

Technical Field

[0001] This invention relates to the field of power energy technology, and in particular to an energy harvesting device, method and online monitoring terminal for high voltage direct current transmission lines. Background Technology

[0002] High-voltage direct current (HVDC) transmission is a key technology for long-distance, high-capacity power transmission. However, unipolar faults can easily cause significant power loss, and early abnormal current changes such as broken conductor strands and overheating joints are subtle. Manual infrared inspection is time-consuming and prone to missed detections. Real-time monitoring of parameters such as current, temperature, and sag of sub-conductors using distributed sensors along the line can achieve precise fault location and early warning. Online monitoring is crucial for the safe operation of DC systems. However, currently used distributed sensors in HVDC transmission scenarios generally suffer from prominent problems such as difficulty in ensuring power supply, insufficient endurance, weak environmental adaptability, and high system operation and maintenance costs, which seriously restrict their long-term stable operation.

[0003] Traditional power supply modes mainly employ two methods: battery power and wired power. Battery power is limited by its own lifespan and requires periodic replacement or replenishment. High-voltage direct current (HVDC) transmission lines span large distances, often traversing uninhabited areas, high mountains, rivers, and lakes, making on-site inspections and battery replacement difficult, costly, and hindering routine maintenance. While external cable power offers advantages such as stable power supply and no need for frequent energy device replacement, it faces several limitations in practical applications: transmission lines are often located in harsh environments like mountains and deserts, making cable laying and equipment installation difficult; power lines are constantly exposed to the elements, making them susceptible to wind and rain erosion, lightning interference, and animal damage, compromising operational reliability; adjustments to monitoring points require rewiring, resulting in poor system flexibility and scalability; high costs are incurred for cable procurement, laying, and insulation protection, leading to high overall construction costs; and laying low-voltage power lines in high-voltage electromagnetic environments places stringent requirements on construction techniques and safety protection, posing significant safety hazards.

[0004] Existing self-powered technologies mainly include electromagnetic energy harvesting, vibration energy harvesting, solar energy harvesting, and wireless power transmission. However, these technologies generally suffer from a mismatch between energy harvesting capacity and sensor power consumption. The total amount of electrical energy that can be harvested from the natural environment and the vicinity of power lines is limited, while the normal operation of sensors requires meeting minimum power consumption requirements. This is especially true for smart sensors with wireless communication and edge computing functions, whose continuous monitoring, data processing, and wireless transmission typically require no less than 0.5W of power. Current energy harvesting levels are insufficient to reliably support their operation. Summary of the Invention

[0005] This invention provides an energy harvesting device, method, and online monitoring terminal for high-voltage direct current (HVDC) transmission lines, to solve the technical problems of low power supply efficiency for sensors in existing high-voltage DC circuits and the inability to provide a continuous and stable power supply for HVDC transmission online monitoring terminals.

[0006] To address the aforementioned technical problems, this invention provides an energy harvesting device for high-voltage direct current transmission lines, comprising: a resistive-capacitive voltage divider energy harvesting module, an MPPT impedance matching module, and a power conversion module. The resistor-capacitor voltage divider energy harvesting module is used to connect to a high-voltage direct current transmission line and output a high-voltage direct current signal. The MPPT impedance matching module is used to adjust the equivalent input impedance of the power conversion module according to the high voltage DC signal, so that the equivalent input impedance matches the impedance of the resistor-capacitor voltage divider energy extraction module. The power conversion module is used to convert the high-voltage DC signal into low-voltage DC based on the current equivalent input impedance.

[0007] As a preferred embodiment, the resistor-capacitor voltage divider energy extraction module includes a resistor chain consisting of several resistors connected in series and a voltage-equalizing capacitor connected in parallel with each resistor; the connection to the high-voltage direct current transmission line and the output of a high-voltage direct current signal specifically includes: Connect to a high-voltage direct current transmission line and collect the high-voltage electrical signal of the high-voltage direct current transmission line; The high-voltage signal is passed through the resistor chain to limit the high-voltage signal to a preset threshold range, and a high-voltage DC signal is output to the MPPT impedance matching module.

[0008] As a preferred embodiment, adjusting the equivalent input impedance of the power conversion module according to the high-voltage DC signal to match the impedance of the resistor-capacitor voltage divider energy extraction module specifically includes: Based on the high-voltage DC signal, the input voltage and input current are sampled and obtained. The equivalent input impedance is calculated based on the input voltage and input current. Adjust the switching frequency in the resistor-capacitor voltage divider power extraction module so that the equivalent input impedance is adjusted and always equal to the impedance of the resistor-capacitor voltage divider power extraction module.

[0009] As a preferred embodiment, the power conversion module includes: a BUCK step-down circuit and an LLC resonant converter circuit; The BUCK step-down circuit is used to reduce the voltage of the high-voltage DC signal to a preset threshold voltage. The LLC resonant converter circuit is used to adjust the switching frequency based on the control of the MPPT impedance matching module and output a stepped-down low-voltage DC power.

[0010] As a preferred embodiment, this device also includes: a capacitor energy storage module; The capacitor energy storage module is used to store the low-voltage DC power converted and output by the power conversion module.

[0011] As a preferred embodiment, the device also includes: a power management control module; The power management control module is used to shut down all loads of the online monitoring terminal and charge the capacitor energy storage module at full power when the energy storage voltage of the capacitor energy storage module is lower than the minimum operating threshold; wherein, the online monitoring terminal includes: sensors and a wireless module, used to monitor the high voltage DC transmission line; When the energy storage voltage of the capacitor energy storage module is in the working range and has not reached the emission threshold, the sensor is driven to perform data sampling and buffering of the high voltage DC transmission line according to a preset cycle. When the energy storage voltage of the capacitor energy storage module is greater than the transmission threshold, the wireless module is woken up and the cached data is sent.

[0012] As a preferred embodiment, this device also includes: a partitioned shielding protection structure; The partitioned shielding protection structure includes: a high-voltage zone, a medium-voltage zone, and a low-voltage zone; insulating partitions are respectively provided between the high-voltage zone, the medium-voltage zone, and the low-voltage zone; the high-voltage zone is provided with a resistive-capacitive voltage divider energy harvesting module, the medium-voltage zone is provided with a BUCK step-down circuit of the power conversion module, and the low-voltage zone is provided with an MPPT impedance matching module and an LLC resonant converter circuit of the power conversion module.

[0013] As a preferred embodiment, the outer periphery of the low-voltage zone is covered with a Faraday shielding layer, which is connected to the ground potential of the low-voltage circuit.

[0014] Accordingly, the present invention also provides an energy harvesting method for high-voltage direct current transmission lines, applicable to the energy harvesting device for high-voltage direct current transmission lines as described in any of the above claims, comprising: The voltage is fed into a high-voltage direct current transmission line through a resistor-capacitor voltage divider module, and the raw high-voltage direct current is obtained. Based on the high voltage DC signal corresponding to the high voltage DC, adjust the equivalent input impedance so that the equivalent input impedance matches the impedance of the resistor-capacitor voltage divider energy extraction module. The resistor-capacitor voltage divider module, after adjusting the equivalent input impedance, converts the original high-voltage DC power to output low-voltage DC power. The low-voltage DC power output is stored through a capacitor energy storage module, and the energy storage voltage of the capacitor energy storage module is monitored. When the energy storage voltage of the capacitor energy storage module is lower than the minimum operating threshold, all loads of the online monitoring terminal are shut down and the capacitor energy storage module is charged at full power; wherein, the online monitoring terminal includes: sensors and a wireless module, used for monitoring the high voltage DC transmission line; When the energy storage voltage of the capacitor energy storage module is in the working range and has not reached the emission threshold, the sensor is driven to perform data sampling and buffering of the high voltage DC transmission line according to a preset cycle. When the energy storage voltage of the capacitor energy storage module is greater than the transmission threshold, the wireless module is woken up and the cached data is sent.

[0015] Accordingly, the present invention also provides an online monitoring terminal, comprising: a sensor and a wireless module, and an energy harvesting device for a high-voltage direct current transmission line as described in any of the above. Both the sensor and the wireless module are electrically connected to the energy harvesting device of the high-voltage direct current transmission line.

[0016] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: The technical solution of this invention, through the coordinated operation of a resistive-capacitive voltage divider energy harvesting module, an MPPT impedance matching module, and a power conversion module, can significantly improve the operational stability and energy conversion efficiency of a distributed sensor self-powered system for high-voltage direct current (HVDC) transmission lines. The resistive-capacitive voltage divider energy harvesting module can be directly connected to the HVDC transmission line, achieving efficient extraction of line-side electrical energy without relying on batteries or external cables. This effectively solves the problems of complex wiring, difficult maintenance, and poor environmental adaptability associated with traditional power supply methods. Simultaneously, the MPPT impedance matching module can adjust the equivalent input impedance of the power conversion module in real time, achieving precise impedance matching with the resistive-capacitive voltage divider energy harvesting module. This ensures that the power conversion module maintains maximum power during the high-voltage to low-voltage conversion process, thereby improving end-to-end high-to-low voltage conversion efficiency and avoiding energy transmission losses caused by line voltage fluctuations and ambient temperature changes. It also ensures stable maximum energy capture even under complex operating conditions, significantly improving energy utilization. Furthermore, the output voltage is stable with low ripple, meeting the continuous power requirements of intelligent sensors for wireless communication and data acquisition, ensuring long-term reliable operation of monitoring equipment, and providing a stable and reliable power supply guarantee for online monitoring devices of HVDC transmission lines. Attached Figure Description

[0017] Figure 1 : A schematic diagram of the structure of an energy harvesting device for a high-voltage direct current transmission line provided in an embodiment of the present invention; Figure 2 : A schematic diagram of the structure of an energy harvesting device for a high-voltage direct current transmission line provided in another embodiment of the present invention; Figure 3: A schematic diagram of an online monitoring terminal for a high-voltage direct current transmission line provided in another embodiment of the present invention; Figure 4 : A schematic diagram of a partitioned shielding protection structure provided in another embodiment of the present invention; Figure 5 : A flowchart illustrating the steps of an energy harvesting method for a high-voltage direct current transmission line provided in an embodiment of the present invention.

[0018] The reference numerals for the accompanying drawings in the specification are as follows: 01. RC voltage divider energy harvesting module; 02. MPPT impedance matching module; 03. Power conversion module; 04. Capacitor energy storage module; 05. Power management and control module; 06. Sensor; 07. Wireless module. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1 Please refer to Figure 1 The present invention provides an energy harvesting device for a high-voltage direct current transmission line, comprising: a resistive-capacitive voltage divider energy harvesting module 01, an MPPT impedance matching module 02, and a power conversion module 03.

[0021] The resistor-capacitor voltage divider energy harvesting module 01 is used to connect to a high-voltage direct current transmission line and output a high-voltage direct current signal.

[0022] As a preferred embodiment, the resistor-capacitor voltage divider energy extraction module 01 includes a resistor chain consisting of several resistors connected in series and a voltage equalizing capacitor connected in parallel with each resistor; the connection to the high-voltage direct current transmission line and the output of a high-voltage direct current signal specifically includes: Connect to the high-voltage direct current transmission line and collect the high-voltage electrical signal of the high-voltage direct current transmission line; pass the high-voltage electrical signal through the resistor chain to limit the high-voltage electrical signal within a preset threshold range, and output the high-voltage direct current signal to the MPPT impedance matching module 02.

[0023] In this embodiment, preferably, the RC voltage divider power harvesting module 01 is composed of a multi-stage series current-limiting resistor chain and a capacitor connected in parallel with each resistor. The RC voltage divider power harvesting module 01 (RC voltage divider power harvesting network) can be used to limit the maximum value of the current flowing through the power harvesting unit, prevent the sudden rise of single-segment voltage or overload, and play the role of current limiting and current regulation.

[0024] For example, the RC voltage divider energy harvesting module 01 is installed on the side of a high-voltage DC conductor with a voltage level of ±500kV or above, bridging the high-voltage DC bus and the reference potential. It is mainly used to directly obtain raw electrical energy from the high-voltage DC transmission line and output a stable high-voltage DC signal, providing a front-end energy source for subsequent energy conversion and load power supply (including online monitoring devices). The front-end of the RC voltage divider energy harvesting network adopts an N-stage RC series structure, where N can be flexibly configured according to the system's withstand voltage requirements; preferably, it can be 50 stages. The core of the RC voltage divider energy harvesting network consists of multiple stages of precision high-voltage resistors connected in series to form a high-voltage resistor chain. The overall total resistance value is preset according to the system's energy harvesting power and safety current limiting requirements; preferably, the design value can reach the 1GΩ level. To achieve voltage balance between each stage of the device, a dedicated voltage-equalizing capacitor with parameters of 100pF / 15kV is connected in parallel across each stage of the high-voltage resistor, forming a parallel RC unit. Multiple such units are then cascaded to form a complete RC voltage divider energy harvesting structure.

[0025] In this embodiment, under steady-state DC operating conditions, the high-voltage resistor chain exhibits high resistance characteristics, which can precisely limit the current taken from the line side to around 500μA. This ensures sufficient energy extraction capability while avoiding excessive current impact on downstream devices, achieving safe and stable energy acquisition. When the overall system encounters strong transient impacts such as lightning overvoltage or circuit breaker operation switching, a steep-front, high-amplitude transient overvoltage will appear on the line side. At this time, the impedance of the resistor branch is relatively large while the impedance of the capacitor branch is significantly reduced. Since the voltage distribution is mainly determined by the capacitance characteristics, the RC voltage divider energy harvesting module 01 can force the voltage borne by each RC unit to tend to be uniform, effectively avoiding local electric field distortion and device breakdown risk caused by concentrated voltage distribution, and improving the insulation reliability and operational stability of the energy harvesting front end in complex electromagnetic environments.

[0026] In this embodiment, the multi-stage series current-limiting resistor chain in the resistor-capacitor voltage divider power harvesting network has a voltage-equalizing capacitor connected in parallel across each resistor stage. The total resistance of the current-limiting resistor chain is in the gigaohm range, used to limit the harvested current to the microamp to milliamp range. It is understood that the design of the multi-stage series current-limiting resistor chain can limit the maximum current flowing through the power harvesting unit, preventing a sharp rise in voltage or overload in a single segment, thus playing a role in current limiting and regulation. Since a single resistor has its maximum operating voltage and rated power, directly connecting a resistor across the ultra-high voltage DC bus and ground is not feasible. By connecting N resistors R1, R2, ..., Rn in series, the total system voltage... The voltage is distributed across each resistive element. Under ideal DC steady-state conditions, if all resistors have a resistance of R, then the voltage across each resistor is... for: The above design ensures voltage stress on any single resistor. It is far below its breakdown voltage threshold. The total current I flowing through this resistive chain, i.e., the draw current, is determined by Ohm's law: Among them, R total This is the total resistance of the resistor chain. This total resistance R... total The design of the resistor is crucial; its value is typically in the gigaohm range, aiming to limit the tapped current I to the microamp or milliamp level. This approach limits the maximum available power at the source with negligible disturbance to the main grid, thereby improving the intrinsic safety of the system. Simultaneously, each resistor... steady-state power loss for By using a high-resistance design, heat dissipation throughout the resistor chain can be effectively controlled, preventing resistance drift or even thermal runaway caused by overheating.

[0027] It should be noted that although voltage distribution is mainly determined by resistance under pure DC conditions, in actual high-voltage DC systems, dynamic processes such as voltage ripple and line transients exist. Under these high-frequency or rapidly changing voltage surges, the stray capacitance to ground at each node in the resistor chain increases. This will severely affect the dynamic distribution of voltage, potentially causing components near the high-voltage end to experience instantaneous voltages far exceeding the average value. To address this issue, this embodiment uses a resistor R in each stage... i A voltage equalizing capacitor is connected in parallel across the two ends. In this circuit, the capacitors form a series capacitor voltage divider. At the instant of a rapid voltage change, the impedance... Much greater than the capacitance impedance Where C represents the voltage equalizing capacitor, and j is the phase of the capacitor current. The angular frequency of the AC signal is represented, and the voltage distribution will be primarily determined by the capacitor network. According to the principle of capacitor voltage division, the voltage across the i-th capacitor... for: in, It is the total equivalent capacitance of all capacitors connected in series. This represents the total voltage of the HVDC system. By setting the capacitance value of each stage, a uniform dynamic voltage distribution can be forced, effectively suppressing the impact of transient overvoltages on local components and greatly improving the system's reliability. The aforementioned parallel RC network structure ensures that voltage stress can be uniformly and effectively controlled under both DC steady-state and AC transient conditions.

[0028] Among these requirements, high-voltage insulation and creepage distance are crucial: When designing the power extraction device for the high-voltage direct current transmission line in this embodiment, special consideration must be given to the requirements of high-voltage insulation and creepage distance to ensure the overall safety of the device. High-voltage insulation mainly relies on the electrical properties of the materials and the structural design. To ensure safety, the electrical insulation level between modules in the power extraction device of this embodiment must meet the corresponding standards. Creepage distance refers to the shortest distance along the insulating surface of an electrical clearance in high-voltage electrical equipment. The creepage distance requirement is mainly used to prevent electrical breakdown caused by surface contamination, moisture, or other environmental factors. Generally, the creepage distance should be designed according to the operating voltage of the system. For the high-voltage direct current power extraction unit, its creepage distance... With operating voltage The relationship between them can be referenced by the following formula: Where k is a constant adjusted according to material and environmental factors. By optimizing the electrical structure, using appropriate materials, and increasing the insulation layer, the design requirements for high-voltage insulation and creepage distance can be met, thereby ensuring the safety and reliability of the equipment.

[0029] In the above embodiments, the resistors and voltage equalizing capacitors can be highly integrated using a multilayer ceramic packaging process. This highly integrated design not only significantly reduces the module size, but also improves electromagnetic compatibility to Class B level through precise thermal management and shielding structures, effectively suppressing high-frequency harmonics from interfering with the surrounding control circuits.

[0030] The MPPT impedance matching module 02 is used to adjust the equivalent input impedance of the power conversion module 03 according to the high voltage DC signal, so that the equivalent input impedance matches the impedance of the resistor-capacitor voltage divider energy extraction module 01.

[0031] In a preferred embodiment, adjusting the equivalent input impedance of the power conversion module 03 according to the high-voltage DC signal to match the impedance of the resistor-capacitor voltage divider energy extraction module 01 specifically includes: Based on the high-voltage DC signal, the input voltage and input current are sampled; based on the input voltage and input current, the equivalent input impedance is calculated; the switching frequency in the RC voltage divider energy extraction module 01 is adjusted so that the equivalent input impedance is adjusted and always equal to the impedance of the RC voltage divider energy extraction module 01.

[0032] In this embodiment, the MPPT (Maximum Power Point Tracking) impedance matching module matches the input voltage V. in and input current I inReal-time sampling and closed-loop adjustment enable dynamic matching of the equivalent input impedance at the energy harvesting end, ensuring that the RC voltage divider energy harvesting module 01 always operates near its maximum output power point. Specifically, a precision sampling circuit continuously acquires the voltage and current output from the front-end RC voltage divider energy harvesting module 01 (i.e., the input voltage V). in and input current I in The system employs MPPT strategies such as perturbation observation, incremental conductance, or fuzzy adaptive methods to determine whether the current operating point deviates from the optimal power point, and outputs control commands accordingly to adjust the switching frequency or drive duty cycle of the internal switching transistors of the power conversion module 03.

[0033] It should be noted that when the switching frequency or duty cycle changes, the equivalent input impedance R of the input port of the power conversion module 03 will change. in Consequently, it changes. Through continuous control and adjustment, the equivalent input impedance R is adjusted. in The system gradually approaches the optimal matching impedance of the resistive-capacitive voltage divider energy harvesting module 01 under the current operating conditions, thereby maintaining the input power near its extreme value. Because this process is continuous, real-time, and closed-loop adaptive, it can quickly respond to changes in external operating conditions. It is understandable that in a high-voltage direct current transmission line environment, factors such as main line voltage fluctuations, conductor temperature changes, and conductor vibration intensity drift can all cause deviations in the output characteristics of the energy harvesting module, leading to a drift in its maximum power point. Traditional fixed impedance matching structures struggle to adapt to such dynamic changes, easily resulting in a significant decrease in energy capture efficiency. However, the MPPT impedance matching module 02 in this embodiment can complete impedance rematching within a millisecond timescale, ensuring that even when main line voltage fluctuations or ambient temperature changes cause energy characteristic drift, the system can still capture energy with maximum efficiency, allowing the system to always extract energy at an efficiency close to the theoretical upper limit.

[0034] In this embodiment, the MPPT impedance matching module 02 has a built-in microcontroller (MCU). The MCU samples the voltage and current output by the RC voltage divider energy harvesting network and dynamically adjusts the switching duty cycle or operating frequency of the cascaded power conversion module 03 to match the equivalent input impedance with the internal resistance of the RC voltage divider energy harvesting module 01. The MPPT impedance matching module 02 achieves adaptive maximum power point tracking by dynamically adjusting the equivalent input impedance, effectively overcoming the efficiency degradation problem caused by energy characteristic drift. It significantly improves the energy capture stability and overall conversion efficiency of the self-powered system under complex and time-varying operating conditions, providing a reliable power supply guarantee for the continuous and stable operation of the sensor 06.

[0035] In this embodiment, the input terminal of the power conversion module 03 is connected to the MPPT impedance matching module 02. The MPPT impedance matching module 02 collects the input voltage and current input to the power conversion module 03, performs impedance calculation, and controls the impedance matching between the power conversion module 03 and the RC voltage divider energy harvesting module 01. That is, by generating corresponding control commands, the switching duty cycle or operating frequency of the cascaded power conversion module 03 is dynamically adjusted so that the equivalent input impedance of the device matches the internal resistance of the RC voltage divider energy harvesting network. Ultimately, the power conversion module 03 is kept stable near the optimal power point within a wide voltage range of ±500kV to ±1100kV, thereby maintaining high conversion efficiency.

[0036] The power conversion module 03 is used to convert the high-voltage DC signal into low-voltage DC based on the current equivalent input impedance.

[0037] As a preferred embodiment, the power conversion module 03 includes: a BUCK step-down circuit and an LLC resonant converter circuit; The BUCK step-down circuit is used to reduce the voltage of the high-voltage DC signal to a preset threshold voltage; the LLC resonant converter circuit is used to adjust the switching frequency based on the control of the MPPT impedance matching module 02, and output the stepped-down low-voltage DC.

[0038] In this embodiment, the power conversion module 03 includes a cascaded non-isolated BUCK step-down circuit and a high-frequency isolated LLC resonant converter circuit, mainly used to convert high-voltage DC signals into low-voltage DC signals. Preferably, in the cascaded power conversion module 03, the first stage uses a multi-level BUCK step-down circuit to reduce the voltage to the 100V intermediate bus; the second stage uses a half-bridge LLC resonant converter circuit, making the switching frequency operate between 200kHz and 500kHz, and the transformer turns ratio is 10:1. The input voltage is sampled in real time by the MCU in the connected MPPT impedance matching module 02. and current And according to the following formula: The switching frequency of the LLC resonant converter circuit is adjusted by perturbation and observation to make the equivalent input impedance... The resistance is always equal to the equivalent internal resistance of the resistor chain in the voltage divider network, thus determining the corresponding maximum power and improving the end-to-end conversion efficiency.

[0039] Implementing the above embodiments has the following effects: The technical solution of this invention, through the coordinated operation of a resistive-capacitive voltage divider energy harvesting module, an MPPT impedance matching module, and a power conversion module, can significantly improve the operational stability and energy conversion efficiency of a distributed sensor self-powered system for high-voltage direct current (HVDC) transmission lines. The resistive-capacitive voltage divider energy harvesting module can be directly connected to the HVDC transmission line, achieving efficient extraction of line-side electrical energy without relying on batteries or external cables. This effectively solves the problems of complex wiring, difficult maintenance, and poor environmental adaptability associated with traditional power supply methods. Simultaneously, the MPPT impedance matching module can adjust the equivalent input impedance of the power conversion module in real time, achieving precise impedance matching with the resistive-capacitive voltage divider energy harvesting module. This ensures that the power conversion module maintains maximum power during the high-voltage to low-voltage conversion process, thereby improving end-to-end high-to-low voltage conversion efficiency and avoiding energy transmission losses caused by line voltage fluctuations and ambient temperature changes. It also ensures stable maximum energy capture even under complex operating conditions, significantly improving energy utilization. Furthermore, the output voltage is stable with low ripple, meeting the continuous power requirements of intelligent sensors for wireless communication and data acquisition, ensuring long-term reliable operation of monitoring equipment, and providing a stable and reliable power supply guarantee for online monitoring devices of HVDC transmission lines.

[0040] Example 2 Please see Figure 2 and Figure 3 This embodiment also provides another preferred solution. Based on embodiment one, the device further includes a capacitor energy storage module 04.

[0041] The capacitor energy storage module 04 is used to store the low-voltage DC power converted and output by the power conversion module.

[0042] In this embodiment, the capacitor energy storage module 04 is connected to the output terminal of the power conversion module for buffer storage of electrical energy. Preferably, the capacitor energy storage module 04 adopts a 100F / 5V electric double-layer capacitor structure (EDLC). By using a power conversion module with a third-order soft-switching topology, the high-voltage DC is stepped down step by step to a stable output of 24V / 5A, so that the capacitor energy storage module 04 can be stably charged. The capacitor energy storage module 04 can support 100,000 charge-discharge cycles.

[0043] As a preferred embodiment, the device further includes a power management control module 05; the power management control module 05 is used to shut down all loads of the online monitoring terminal and charge the capacitor energy storage module 04 at full power when the energy storage voltage of the capacitor energy storage module 04 is lower than the minimum operating threshold; wherein, the online monitoring terminal includes a sensor 06 and a wireless module 07, used to monitor the high-voltage direct current transmission line; when the energy storage voltage of the capacitor energy storage module 04 is in the operating range and has not reached the transmission threshold, the sensor 06 is driven to perform data sampling and buffering of the high-voltage direct current transmission line according to a preset cycle; when the energy storage voltage of the capacitor energy storage module 04 is greater than the transmission threshold, the wireless module 07 is woken up and the buffered data is transmitted.

[0044] In this embodiment, the power management control unit is the core control component of this energy harvesting device. It is responsible for the fine-grained scheduling and management of energy harvesting by the front-end resistor-capacitor voltage divider network, the intermediate capacitor energy storage module 04, and the back-end sensing and communication loads. The power management control unit adopts the ordered control logic of a three-level state machine, and divides different working modes according to the real-time voltage state of the energy storage element to realize the coordinated operation of energy harvesting, storage, sensing, and communication, ensuring the system operates stably, reliably, and with low power consumption under limited energy harvesting conditions.

[0045] It should be noted that during the startup phase, when the terminal voltage of the supercapacitor or other energy storage element is detected to be lower than the system's set minimum operating threshold, the power management control unit immediately executes a protective control strategy, actively cutting off all load circuits, including those for sensor 06 sampling, data processing, and wireless communication. This allows the entire system to enter a pure energy storage charging mode. At this time, only the resistor-capacitor voltage divider module, MPPT impedance matching module, and power conversion module ensure that they convert high-voltage DC power at their maximum power point to rapidly charge the capacitor energy storage module 04. All energy acquired during this phase is prioritized for capacitor energy storage to prevent device malfunction or startup failure due to insufficient power supply. This ensures that the energy storage voltage quickly recovers to a safe operating range, laying the energy foundation for subsequent stable operation. The minimum operating threshold can be manually set according to the actual working devices and the data acquisition requirements of sensor 06.

[0046] It should be noted that when entering the sleep phase, the energy storage voltage has risen back to the normal operating range, but has not yet reached the energy threshold required for wireless data transmission. At this time, the power management control unit only maintains the periodic power-on sampling of the low-power sensor 06 module, while the other high-power modules remain off. After completing weak signal acquisition, analog-to-digital conversion, and preliminary preprocessing according to a preset time period, sensor 06 temporarily stores the valid data in the on-chip buffer unit and does not perform data transmission operations to minimize instantaneous power consumption and extend the energy storage duration. The energy threshold can be manually set according to actual transmission requirements and the amount of mission data.

[0047] It should be noted that when the energy storage voltage continues to accumulate and reaches the set energy threshold for transmission, the system automatically switches to the communication phase. The power management control unit instantly activates the wireless communication module, reads the stored monitoring data from the cache, and completes data packaging, modulation, and remote uploading according to the preset communication protocol. After data transmission is completed, the capacitor energy storage module 04 automatically switches back to the corresponding state based on the current energy storage voltage level, continuing to perform energy harvesting and cyclic scheduling, thereby achieving dynamic matching between energy supply and load power consumption, improving the overall energy utilization rate and operational reliability of the system.

[0048] For example, during the startup phase, if the energy storage voltage The power management control unit shuts down the wireless module 07 and the power line sensing sensor 06, entering pure charging mode. During the sleep / sampling phase, if... During this time, the power management control unit wakes up every minute to drive the MEMS current sensor 06 to sample for 50ms and then store the data in memory to maintain low system power consumption. During the communication phase, when the energy storage voltage... At this time, the power management control unit wakes up the LoRa or 4G / 5G communication module, sends the 60 sets of buffered data at once, and then returns to sleep state.

[0049] Example 3 Please see Figure 4 This embodiment also provides another preferred solution. Based on Embodiment 1, the device further includes: a partitioned shielding protection structure.

[0050] The partitioned shielding protection structure includes: a high-voltage zone, a medium-voltage zone, and a low-voltage zone; insulating partitions are respectively provided between the high-voltage zone, the medium-voltage zone, and the low-voltage zone; the high-voltage zone is provided with a resistive-capacitive voltage divider energy harvesting module, the medium-voltage zone is provided with a BUCK step-down circuit of the power conversion module, and the low-voltage zone is provided with an MPPT impedance matching module and an LLC resonant converter circuit of the power conversion module.

[0051] As a preferred embodiment, the outer periphery of the low-voltage zone is covered with a Faraday shielding layer, which is connected to the ground potential of the low-voltage circuit.

[0052] In this embodiment, the partitioned electromagnetic protection structure shell is integrally cast with special epoxy resin, possessing excellent insulation strength, mechanical stability, and environmental adaptability, and can meet the long-term reliable operation requirements under ±500kV and above high-voltage DC strong electric field environments. The interior of the shell is divided into three independent functional areas—high-voltage, medium-voltage, and low-voltage—through a structured spatial layout, each housing circuit modules at different potential levels: the high-voltage area is used to install a resistive-capacitive voltage divider power extraction module; the medium-voltage area integrates a BUCK step-down converter circuit; and the low-voltage area houses an LLC resonant converter circuit, an MPPT impedance matching module, and MEMS sensors, achieving physical separation and functional zoning of high, medium, and low voltage potentials, and avoiding mutual interference between modules at different potentials.

[0053] It should be noted that, preferably, to optimize the electric field distribution and suppress partial discharge, the edges of all metal structural components inside the structure are precision-processed into rounded corner structures with a radius of not less than 10mm. By increasing the radius of curvature, the phenomenon of field strength concentration at the tip is eliminated, thus avoiding tip discharge and corona generation from the structural design. The outer side of the low-voltage area is covered with a fully enclosed copper thin film to form a continuous and complete Faraday cage shield, which is reliably connected to the ground potential of the low-voltage system. This can effectively block electrostatic coupling interference and spatial electromagnetic radiation interference caused by the external 500kV high-voltage DC electric field, significantly reduce sensing signal noise, improve the signal-to-noise ratio of the MEMS sensor by 15dB, and effectively ensure the accuracy of weak signal acquisition.

[0054] In this embodiment, dedicated insulating partitions are installed between the high-voltage, medium-voltage, and low-voltage zones for electrical isolation. Combined with a refined spatial layout design, this maximizes the electrical clearance and creepage distance between circuits of different voltage levels, blocking potential surface discharge and air breakdown paths, and fundamentally eliminating the risk of internal flashover. Simultaneously, the outer surface and internal high-voltage electrodes of the partitioned shielding structure employ a large radius of curvature rounded corner transition design to further homogenize the overall electric field distribution and suppress local electric field distortion. Through multiple technical means of insulation separation, electric field optimization, and electromagnetic shielding, highly reliable protection in strong electric field environments is achieved. This ensures electrical safety between high and low voltage systems, enhances the anti-interference capability of the sensing module, and ensures stable and safe operation of the device in high-voltage DC transmission line scenarios.

[0055] Example 4 Please see Figure 5 This invention provides a method for harvesting energy from high-voltage direct current (HVDC) transmission lines, applicable to the energy harvesting device for HVDC transmission lines as described in Embodiment 1 above, and includes the following steps S101-S103: S101: Connects to the high-voltage direct current transmission line through the resistor-capacitor voltage divider module and obtains the original high-voltage direct current.

[0056] S102: Adjust the equivalent input impedance according to the high voltage DC signal corresponding to the high voltage DC, so that the equivalent input impedance matches the impedance of the resistor-capacitor voltage divider energy extraction module.

[0057] S103: The resistor-capacitor voltage divider module, after adjusting the equivalent input impedance, converts the original high-voltage DC power to output low-voltage DC power.

[0058] As a preferred embodiment, the method further includes S104-S107: S104: Store the output low-voltage DC power through the capacitor energy storage module and monitor the energy storage voltage of the capacitor energy storage module.

[0059] S105: When the energy storage voltage of the capacitor energy storage module is lower than the minimum operating threshold, all loads of the online monitoring terminal are turned off and the capacitor energy storage module is charged at full power; wherein, the online monitoring terminal includes: sensors and a wireless module, used to monitor the high voltage DC transmission line.

[0060] S106: When the energy storage voltage of the capacitor energy storage module is in the working range and has not reached the transmission threshold, the sensor is driven to perform data sampling and buffering of the high voltage DC transmission line according to the preset cycle.

[0061] S107: When the energy storage voltage of the capacitor energy storage module is greater than the transmission threshold, the wireless module is woken up and the cached data is sent.

[0062] In this embodiment, the coordinated operation of the RC voltage divider energy harvesting module, MPPT impedance matching module, power conversion module, and capacitor energy storage module enables efficient energy acquisition, conversion, storage, and load scheduling, ensuring the stable and orderly operation of online monitoring. The RC voltage divider energy harvesting module connects to the high-voltage direct current (HVDC) transmission line, acquiring raw HVDC power from the line based on the RC voltage divider principle, providing stable initial energy support for the entire monitoring system. Based on this, the electrical signal corresponding to the HVDC power is acquired, and the equivalent input impedance is dynamically adjusted to achieve precise matching with the impedance of the RC voltage divider energy harvesting module, thereby maximizing energy capture efficiency. Then, the impedance-adjusted power conversion module converts the raw HVDC power into low-voltage DC power suitable for subsequent energy storage and load operation, laying the foundation for the stable operation of the entire system.

[0063] In this embodiment, after low-voltage DC power is output, the energy is stored by a capacitor energy storage module. Simultaneously, the power management control unit monitors the energy storage voltage of the capacitor energy storage module in real time, using this as the core basis for load scheduling. Differentiated control strategies are executed based on different energy storage voltage states: when the energy storage voltage is below the minimum operating threshold, all loads of the online monitoring terminal (including sensors and wireless modules used for line monitoring) are immediately shut down, and all acquired energy is concentrated on charging the capacitor energy storage module, ensuring the energy storage voltage quickly recovers to a safe range; when the energy storage voltage is within the normal operating range but has not reached the data transmission threshold, the sensors are activated according to a preset cycle to sample and cache relevant data from the high-voltage DC transmission line, minimizing energy consumption; when the energy storage voltage accumulates to exceed the transmission threshold, the wireless module is promptly activated to remotely transmit the cached monitoring data, achieving effective data transmission. Through the RC voltage divider energy harvesting module, MPPT impedance matching module, power conversion module, and capacitor energy storage module, efficient coordination between self-powering and monitoring is achieved, effectively ensuring the long-term stable operation of the system.

[0064] Implementing the above embodiments has the following effects: The technical solution of this invention, through the coordinated operation of a resistive-capacitive voltage divider energy harvesting module, an MPPT impedance matching module, and a power conversion module, can significantly improve the operational stability and energy conversion efficiency of a distributed sensor self-powered system for high-voltage direct current (HVDC) transmission lines. The resistive-capacitive voltage divider energy harvesting module can be directly connected to the HVDC transmission line, achieving efficient extraction of line-side electrical energy without relying on batteries or external cables. This effectively solves the problems of complex wiring, difficult maintenance, and poor environmental adaptability associated with traditional power supply methods. Simultaneously, the MPPT impedance matching module can adjust the equivalent input impedance of the power conversion module in real time, achieving precise impedance matching with the resistive-capacitive voltage divider energy harvesting module. This ensures that the power conversion module maintains maximum power during the high-voltage to low-voltage conversion process, thereby improving end-to-end high-to-low voltage conversion efficiency and avoiding energy transmission losses caused by line voltage fluctuations and ambient temperature changes. It also ensures stable maximum energy capture even under complex operating conditions, significantly improving energy utilization. Furthermore, the output voltage is stable with low ripple, meeting the continuous power requirements of intelligent sensors for wireless communication and data acquisition, ensuring long-term reliable operation of monitoring equipment, and providing a stable and reliable power supply guarantee for online monitoring devices of HVDC transmission lines.

[0065] Example 5 Please see Figure 3 The present invention provides an online monitoring terminal, comprising: a sensor 06, a wireless module 07, and an energy harvesting device for a high-voltage direct current transmission line as described in any of the above items; Both the sensor 06 and the wireless module 07 are electrically connected to the energy harvesting device of the high-voltage direct current transmission line.

[0066] The energy harvesting device of the high-voltage direct current transmission line is used to implement the various steps in Embodiment 4 above, for example... Figure 3 Steps S101 to S103 are shown.

[0067] As the core sensing component of the online monitoring terminal, Sensor 06 is selected and its performance and deployment are adapted to the operating characteristics of high-voltage direct current transmission lines. Different types of sensing units can be configured according to monitoring needs, including but not limited to current sensors, voltage sensors, temperature sensors, and insulator leakage current sensors. All types of sensors adopt a high-voltage and electromagnetic interference-resistant packaging design, enabling stable operation in the high-voltage and strong electromagnetic environment of transmission lines. They collect key electrical parameters, environmental parameters, and equipment status parameters in real time during line operation, converting physical quantity signals into transmittable electrical signals to provide raw data support for subsequent data processing and analysis, ensuring the accuracy and reliability of monitoring data.

[0068] The wireless module 07 is used for data transmission during monitoring. It employs a low-power, high-stability wireless communication protocol, adapting to the complex communication environment of high-voltage transmission lines in the field, enabling long-distance, low-latency transmission of monitoring data. After being electrically connected to the power harvesting device of the high-voltage DC transmission line, the wireless module 07 receives a stable power supply from the device, avoiding the drawbacks of periodic battery replacement required in traditional battery-powered modes and reducing terminal maintenance costs. Simultaneously, the wireless module 07 features data encryption, encrypting monitoring data during transmission to prevent tampering and theft, ensuring the security of transmission line operation data, and enabling real-time uploading of monitoring data to the back-end monitoring center, facilitating remote monitoring of the line's operational status by staff.

[0069] The power harvesting device of the high-voltage direct current (HVDC) transmission line serves as the core power source for the entire online monitoring terminal. Its output voltage and power are precisely matched to simultaneously meet the power consumption requirements of both sensor 06 and wireless module 07, ensuring their stable and coordinated operation. By sensing the electromagnetic or electrical energy of the HVDC transmission line, the power harvesting device, after rectification, filtering, and voltage stabilization, outputs a stable DC power supply. This not only provides a continuous and reliable power supply for sensor 06 and wireless module 07 but also features overvoltage, overcurrent, and undervoltage protection functions. This effectively prevents damage to the sensor and wireless module caused by voltage fluctuations and instantaneous impacts, extending the service life of the terminal equipment.

[0070] The electrical connections between sensor 06, wireless module 07, and the power harvesting device for the high-voltage direct current transmission line utilize specialized waterproof, corrosion-resistant, and aging-resistant electrical connection cables. The connection nodes are sealed to ensure compatibility with the harsh outdoor working environment of high-voltage transmission lines, including high temperatures, high humidity, and frequent sandstorms. This prevents terminal equipment failure due to loose connections, poor contact, or line aging. Furthermore, the integrated circuit design of these three components reduces the size of the terminal equipment, facilitating installation and deployment at various locations such as transmission line towers and insulators without affecting the normal operation of the transmission line. This enables comprehensive, blind-spot-free online monitoring of the high-voltage direct current transmission line.

[0071] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. An energy harvesting device for a high-voltage direct current transmission line, characterized in that, include: RC voltage divider energy extraction module, MPPT impedance matching module and power conversion module; The resistor-capacitor voltage divider energy harvesting module is used to connect to a high-voltage direct current transmission line and output a high-voltage direct current signal. The MPPT impedance matching module is used to adjust the equivalent input impedance of the power conversion module according to the high voltage DC signal, so that the equivalent input impedance matches the impedance of the resistor-capacitor voltage divider energy extraction module. The power conversion module is used to convert the high-voltage DC signal into low-voltage DC based on the current equivalent input impedance.

2. The energy harvesting device for a high-voltage direct current transmission line as described in claim 1, characterized in that, The resistor-capacitor voltage divider energy extraction module includes a resistor chain consisting of several resistors connected in series and a voltage-equalizing capacitor connected in parallel with each resistor; the connection to the high-voltage direct current transmission line and the output of a high-voltage direct current signal specifically includes: Connect to a high-voltage direct current transmission line and collect the high-voltage electrical signal of the high-voltage direct current transmission line; The high-voltage signal is passed through the resistor chain to limit the high-voltage signal to a preset threshold range, and a high-voltage DC signal is output to the MPPT impedance matching module.

3. The energy harvesting device for a high-voltage direct current transmission line as described in claim 1, characterized in that, The step of adjusting the equivalent input impedance of the power conversion module according to the high-voltage DC signal to match the impedance of the resistive-capacitive voltage divider energy extraction module specifically includes: Based on the high-voltage DC signal, the input voltage and input current are sampled and obtained. The equivalent input impedance is calculated based on the input voltage and input current. Adjust the switching frequency in the resistor-capacitor voltage divider power extraction module so that the equivalent input impedance is adjusted and always equal to the impedance of the resistor-capacitor voltage divider power extraction module.

4. The energy harvesting device for a high-voltage direct current transmission line as described in claim 3, characterized in that, The power conversion module includes: a BUCK step-down circuit and an LLC resonant converter circuit; The BUCK step-down circuit is used to reduce the voltage of the high-voltage DC signal to a preset threshold voltage. The LLC resonant converter circuit is used to adjust the switching frequency based on the control of the MPPT impedance matching module and output a stepped-down low-voltage DC power.

5. The energy harvesting device for a high-voltage direct current transmission line as described in any one of claims 1-4, characterized in that, Also includes: Capacitor energy storage module; The capacitor energy storage module is used to store the low-voltage DC power converted and output by the power conversion module.

6. The energy harvesting device for a high-voltage direct current transmission line as described in claim 6, characterized in that, Also includes: Power management control module; The power management control module is used to shut down all loads of the online monitoring terminal and charge the capacitor energy storage module at full power when the energy storage voltage of the capacitor energy storage module is lower than the minimum operating threshold; wherein, the online monitoring terminal includes: sensors and a wireless module, used to monitor the high voltage DC transmission line; When the energy storage voltage of the capacitor energy storage module is in the working range and has not reached the emission threshold, the sensor is driven to perform data sampling and buffering of the high voltage DC transmission line according to a preset cycle. When the energy storage voltage of the capacitor energy storage module is greater than the transmission threshold, the wireless module is woken up and the cached data is sent.

7. The energy harvesting device for a high-voltage direct current transmission line as described in any one of claims 1-4, characterized in that, It also includes: partitioned shielding protection structure; The partitioned shielding protection structure includes: a high-voltage zone, a medium-voltage zone, and a low-voltage zone; insulating partitions are respectively provided between the high-voltage zone, the medium-voltage zone, and the low-voltage zone; the high-voltage zone is provided with a resistive-capacitive voltage divider energy harvesting module, the medium-voltage zone is provided with a BUCK step-down circuit of the power conversion module, and the low-voltage zone is provided with an MPPT impedance matching module and an LLC resonant converter circuit of the power conversion module.

8. The energy harvesting device for a high-voltage direct current transmission line as described in claim 7, characterized in that, The outer periphery of the low-voltage zone is covered with a Faraday shielding layer, which is connected to the ground potential of the low-voltage circuit.

9. A method for energy harvesting in a high-voltage direct current transmission line, characterized in that, The energy harvesting device applied to the high-voltage direct current transmission line according to any one of claims 1-8 comprises: The voltage is fed into a high-voltage direct current transmission line through a resistor-capacitor voltage divider module, and the raw high-voltage direct current is obtained. Based on the high voltage DC signal corresponding to the high voltage DC, adjust the equivalent input impedance so that the equivalent input impedance matches the impedance of the resistor-capacitor voltage divider energy extraction module. The resistor-capacitor voltage divider module, after adjusting the equivalent input impedance, converts the original high-voltage DC power to output low-voltage DC power. The low-voltage DC power output is stored through a capacitor energy storage module, and the energy storage voltage of the capacitor energy storage module is monitored. When the energy storage voltage of the capacitor energy storage module is lower than the minimum operating threshold, all loads of the online monitoring terminal are shut down and the capacitor energy storage module is charged at full power; wherein, the online monitoring terminal includes: sensors and a wireless module, used for monitoring the high voltage DC transmission line; When the energy storage voltage of the capacitor energy storage module is in the working range and has not reached the emission threshold, the sensor is driven to perform data sampling and buffering of the high voltage DC transmission line according to a preset cycle. When the energy storage voltage of the capacitor energy storage module is greater than the transmission threshold, the wireless module is woken up and the cached data is sent.

10. An online monitoring terminal, characterized in that, include: Sensors and wireless modules, and energy harvesting devices for high-voltage direct current transmission lines as described in any one of claims 1-8; Both the sensor and the wireless module are electrically connected to the energy harvesting device of the high-voltage direct current transmission line.

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