Motivation
In the United States alone, there are an estimated 180 million utility poles. Both ubiquitous and completely vital, utility poles carry power, telephone, and cable lines. While a few of these poles are concrete or steel, the vast majority are wood and are thus susceptible to decay and failure. A properly treated wooden utility pole can have a lifespan of 25-50 years, a figure which heavily depends on the climate around it as both moisture and strong winds can compromise the integrity of the pole. Utility poles can also be severely impacted by more active hazards, including car crashes and insect infestation.
Concept
We propose a device that can be mounted on utility poles to monitor their structural integrity. Our device will include sensors to detect the tilt of the pole and will be able to detect hazardous events such as tampering or motor vehicle collision. As an additional application, our device will provide substation monitoring of the electric grid through a component that will be mounted near the power distribution line insulators on the pole. This will also allow our device to harvest the energy from the magnetic field produced by the power lines. The use of energy harvesting will allow our project to minimally invasive and have low upkeep costs.
Our devices will be able to communicate with the central service station via a wireless network. This information can be used by local service providers with an array of functionality: from monitoring the power quality in a specific region to determining when a pole is likely to fall and needs maintenance.
Current Solutions
Wireless power line sensors
Currently, several companies actively market substation monitoring solutions that include wireless power line sensors, a gateway/receiver, and application software. These line mount sensors harvest energy from the magnetic fields induced by the AC power line. Typically, they are capable of measuring the power line current and they communicate over 2.4 GHz radio, cellular, or Wifi networks. Our project will improve upon these products by featuring a battery in case of power outages, on-chip current and temperature monitoring to detect faults and monitor power quality, and communication over LP-WAN rather than power-intense cellular or Wifi networks. Also, as all of these sensors are mounted on the line, they provide no information about the state of the utility pole.
Utility pole technicians
In order to determine the structural integrity of a utility pole, currently utility companies are required to send technicians to assess each individual pole. Methods of assessment include visual inspection, sounding and boring, and Resistograph testing. Many poles are simply visually inspected by a technician for signs of decay, cracks, and insect or bird damage. Sounding and boring requires a technician to strike the pole with a hammer and listen to the resulting tone, whereas boring requires a hole to be bored into the pole to look for decay. The very act of boring can compromise the integrity of a pole. Resistograph testing involves drilling a small hole and measuring the resistance of the wood to the drill. Our project will greatly improve on these methods by allowing remote monitoring of pole status.
