Energy Management Strategies Of Nodes For WSNs Based On Photovoltaic Energy Harvesting

The concept of "perceived China" brings new opportunities for the development and application of wireless sensor network(WSNs)technology.However,the power of traditional WSNs is very limited in its initial configuration.People have adopted measures such as low-power technology and energy-efficient routing protocols to maximize the network lifetime.However,the problem of node battery energy limitation has not been completely solved,which seriously restricts the promotion of WSNs.In order to fundamentally solve this problem,designing nodes that obtain energy from the environment has become a research hotspot in this field.Therefore,rechargeable wireless sensor nodes emerged.In the field application environment of WSNs,the acquisition of solar energy is relatively easy.Therefore,solar energy-based rechargeable wireless sensor networks(SP-WSNs)are becoming more and more important to scholars and experts.However,the energy collected by sensor nodes tends to fluctuate greatly due to geographical location,season,and weather.Therefore,how to improve the node's energy efficiency and how to distribute and manage the collected energy reasonably becomes a key problem for solar rechargeable sensor nodes.In order to overcome the deficiencies of the existing technologies,this thesis focuses on the issues of energy harvesting and energy consumption of SP-WSNs nodes.The main tasks are as follows:(1)In order to meet the requirements of small and lightweight node applications,the area of solar panels should be as small as possible.At the same time,we must try our best to improve the energy efficiency of solar panels and achieve the best match between the maximum energy harvesting effect of small-sized solar panels and the energy consumption of the water quality monitoring nodes in the Three Gorges reservoir area.This thesis designs a node energy harvesting device that adaptively tracks sunlight.The device adopts a dynamic tracking solar light technology to adjust the height and azimuth angle of the solar panel in real time so that it is always in the direction of the strongest incident sunlight.Thereby realizing the maximum absorption of solar light by the solar panel,and substantially improve the node's energy efficiency.(2)In order to improve the energy utilization rate of the nodes and reduce the energy distribution error at the same time,this thesis constructs the Energy Neutral Management Mechanism Based on Historical Harvested Energy.The mechanism adjusts the duty cycle of the node in the next operating cycle according to the available energy converted from solar energy in the current operating cycle,so that the energy consumption of the node is less than or equal to the node energy,ensuring that the node has been in an energy-neutral state,so as to achieve a reasonable distribution of energy and full use,and then achieve the node's sustainable work.(3)In the experiments and simulations,firstly,the on-site measurement of the energy harvesting device with self-adaptive tracking of solar energy designed in this thesis was performed,and the energy data of different weather and different time periods during the day were collected and analyzed to verify its performance relative to the fixed nodes.The device's energy efficiency improves.Then the MATLAB simulation platform was used to simulate the Energy Neutral Management Mechanism Based on Historical Harvested Energy proposed in this thesis.The simulation results of relevant performance indicators such as energy distribution errors were compared to verify the advantages of this mechanism in energy distribution management.Finally,according to the energy-neutral management mechanism based on historical energy harvesting,different water quality detection sensor nodes were tested combined with the laboratory's water quality inspection platform in the Three Gorges reservoir area.By adjusting the duty cycle of the sensor node,the balance between the energy harvesting and the energy dissipation of the node can be verified,so as to achieve the optimal matching of the maximum energy harvesting of the small-sized solar panel and the node energy consumption.