Research Of Electric Field Energy Harvesting Away From High Voltage Transmission Lines

High voltage transmission lines(HVTL) are the arteries of power system, and on-line condition monitoring devices(CMD) are needed for the safe operating of HVTL. For HVTL applications, CMDs are usually installed on a transmission tower, reliable and sustainable power supply is key and indispensable for CMDs. The power supply has been a bottleneck that limits the performance of on-line CMDs. Currently, CMDs on the transmission towers are powered by a combination of solar photovoltaic(PV) cells and battery packs. This is a limitation as it creates a serious dependence of the operation on the microclimate around the tower. It is known that solar PV generation cannot provide a reliable and sufficient electric power supply when it rains or under cloud cover for long time durations. However, it is under these conditions that the on-line CMD needs to remain operational.The research in this paper focus on the electric field energy harvesting technologies away from HVTL, beased on capacitive divider and resonant transducer, respectively, and the scheme of power supply based on the technology of electric field energy resonant harvesting. The research focused on:1) The simulation model of electric field around the transmission tower was proposed, and the electric field distribution on the transmission tower was analysed, and the appropriate position for electric field energy harvester was discussed. Palisade harvester was proposed based on the fringe effect of plate capacitor.2) The principle of electric field energy harvesting technology based on capacitor divider on the tower is researched, and the electrostatic field model and cicuit model were proposed. The characteristics of voltage and charge on the electric field energy harvesting plate was analyzed, and the harvesting circuit using switch was calculated with the law of conservation of charge, the result denoted the usage of swith can not promote the electric field energy harvesting, and a new eclectric field energy harvesting circuit was designed.3) The electric field energy harvesting technology with resonant transducer away from HVTL was prposed for the first time, and the circuit model was built and the output power equation was deduced. The characteristics of magnetizing impedance of electric field resonant transducer was analyzed and the calculation method was given. The winding capacitance and the load characteristic of the resonant transducer was researched. The design method of electric field resonant transducer was proposed, such as core material, core loss, sectional area of the core and winding capacitance.4) Electric field resonant transducers were made to verify the circuit model of electric field energy harvesting. The power harvested by the resonant transducer agree with the the result calculated by the circuit model. The harvested power can imoproved through reducing the power factor of the load was proved by experiment. A ring capacitor model with thin layer was proposed, and its capacitance function was proved to be the odd function of voltage on it, that is the reason why the FFT of the current flow throuth resonant transducers has odd harmonics only. The influence of corona and humiture to the electric field energy harvesting was also researched by experiment.5) The application technologies of electric field energy harvesting with resonant transducer were also researched, including the parallel connection of harvesting system, selection of rated voltage, protection of overvoltage, accumulation of electric energy with lithium battery and ultracapacitor. The impact of electric field energy harvesting system to the leakage current on the insulator chain was discussed. A scheme of distributed electromagnetic energy harvesting was proposed to take a full advantage of the energy around the HVTL.