| Overhead transmission lines are the branches and skeletons of the power system.The use of large-scale micro-power equipment for real-time security status monitoring can ensure the safe operation of the transmission system effectively.However,the power supply problem is one of the bottlenecks of micro-power equipment on transmission lines which restricts the development of monitoring technology.In some cases,there are difficulties of single power supply such as instability,large environmental impact,and inconvenient replacement of lithium batteries.The development of power electronics technology has promoted the continuous reduction of power consumption of equipment on overhead transmission lines,and also made it possible to use the ambient energy around the overhead lines to power its micro-power equipment.In this paper,a hybrid power supply which uses environmental energy include magnetic field energy,solar energy and lithium battery power supply is studied for micro power equipment on overhead transmission lines.It can not only prolong the service life of lithium battery in traditional equipment,but also improve the reliability of power supply.At the same time,it can also implement the country’s goal of ’carbon peak,carbon neutrality’.Therefore,the study of the hybrid power supply has the good engineering significance.In this paper,the two kinds of environmental energy were analyzed theoretically and simulated,and the methods of broadening the range of magnetic field energy and improving the energy conversion rate were explored.Secondly,the conversion circuit and energy management scheme were designed.The magnetic field energy,solar energy and lithium battery energy are combined that can be used as a stable power supply for micro-power equipment to achieve the purpose of efficient energy utilization.Finally,an experimental platform was built to verify that the designed power supply has the good practical application ability.The magnetic core material,size and number of turns of the coil were determined.For the purpose of the output voltage of the coil is not less than 7V and the output power is not less than 0.5W,the COMSOL Multiphysics finite element simulation software was used to simulate the magnetic field and the circuit,and the output characteristics of the magnetic field energy were studied.According to the primary current value,the magnetic core material and the number of turns of the coil were designed to avoid the dead zone and saturation of the magnetic core.The hardware circuit and energy management scheme of the power supply were designed.The hardware circuit includes four modules: environmental energy,conversion circuit,energy storage and load,and energy management.They can convert the obtained magnetic field energy and solar energy into low-voltage 3.3V DC to meet the demand of micro-power load.Through the energy management scheme,the two kinds of environmental energy are combined with the lithium battery to supply power,so that the energy is reasonably distributed,the magnetic field energy range is widened,and the improved MPPT control method is used to make the photovoltaic cell output at maximum power.An experimental platform was built to verify the feasibility of the hybrid power supply and the experimental results were analyzed.Through the load test of two kinds of magnetic cores,the relationship between the secondary side voltage of the coil and the primary current,the number of turns and the load was obtained,and the correctness of the simulation conclusion and the load capacity of the power supply were verified.The feasibility of the energy management scheme was verified by the overall test of the hybrid power supply.Power supply for wireless communication modules such as Bluetooth and Lo Ra verified the practicability of the power supply. |
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