Study On Ambient Energy Harvesting Methods For Low-power Online Monitoring Devices

The operational condition of power equipments and transmission lines is quite significant to the stable and reliable operation of the whole power grid. Real-time condition parameters can be monitored by the online monitoring technology, which helps to reflect the insulation status of power equipments effectively. However, difficulties in providing power supply for online monitoring devices remain to be a longstanding problem in some occasions and it restricts the development of online monitoring for power equipments. In order to solve it, ambient energy harvesting has been proposed in this paper and the converted electricity can provide power supply for some low-power online monitoring devices. Besides, magnetic field energy, mechanical vibration energy, and thermoelectric energy have been accessed by hybrid energy management system, which improves the insufficient power capacity and instability of the existing energy harvesting system for scavenging single type of ambient energy. The energy harvesting topology proposed in the paper also provides indications to engineering application.In the paper, piezoelectric harvesters, thermoelectric modules and a kind of stick-on magnetic energy harvester have been employed to scavenge vibration, thermal and magnetic energy respectively. Firstly, theoretical analysis has been implemented on the conversion properties of the four energy sources. And experimental platform has been constructed aiming at investigating the energy harvesting performance. Then the output power has been evaluated respectively based on the experiment results, followed by optimization analysis on maximizing the output capacity.With considerations of different properties of output from the energy converters, low-power energy management circuit has been structured, which can manage the input power with little power consumption drawn from the sources. Different AC or DC input voltages can be regulated into stable 3.3V DC specified by loads such as wireless sensors. And the feasibility of the hybrid energy access has been verified by experiments.Eventually, experiments with load have been conducted on Zig Bee network. The power consumption of Zig Bee nodes in different modes has been tested. Whereafter the wireless temperature metering experiment has been conducted. It was observed that the Zig Bee sensor node was successfully activated and kept in successive service by the designed power supply based on ambient energy harvesting. Generally, energy harvesting methods and the circuit topology proposed in the paper has been verified ultimately.