| It is well known and accepted that the US power grid is aging and the investments made in this space have been low over the last few decades. Given that the growth in electricity demand is projected to be approximately 3% per year, the power system is expected to witness excessive electrical and thermal stresses in the foreseeable future, if proactive measures are not undertaken. This situation is further exacerbated with the introduction of renewable energy technologies, such as wind and solar. These renewable sources of energy are intermittent and mostly located away from the load centers. Therefore, increasing penetration of such technologies necessitates additional transmission and distribution builds. Without additional investments on the grid assets, the stresses imposed on the grid are expected to further amplify. In such an environment, maintaining high reliability of the grid becomes challenging due to limited visibility of the grid parameters and low situational awareness.;Moreover, as the assets become old they require increased maintenance. Given that currently a periodic maintenance regime is followed, the cost of ownership of the asset increases. A theoretical solution to this problem could be replacement of all the assets on the grid. However, revamping a ;However, the utility grid as a whole lacks intelligent sensing technologies as the cost of present day sensors is high. Furthermore, wireless sensing units available in the market are large and bulky, with some requiring batteries for operation and therefore demanding periodic maintenance.;This dissertation presents the concept of a small, low-cost, self-powered smart wireless sensor that can be used for monitoring current, temperature and voltage on a variety of utility assets. Wireless sensor network architecture for integrating these sensors to information systems, such as SCADA, are proposed. The role of the proposed sensor is to provide real-time information and min-max history of asset parameters, and to detect faults and absence of power on assets. Novel energy harvesting approaches are proposed that enable the sensor to operate without batteries and to have an expected life of 20-30 years.;The sensor measures current flowing in an asset using an open ferromagnetic core, unlike a CT which uses a closed core, which makes the proposed sensor small in size, and low-cost. Further, it allows the sensor to operate in conjunction with different assets having irregular geometries, such as bus-bars, cables, overhead conductors, transformers, and shunt capacitors, and function even when kept in the vicinity of an asset. The proposed self-powered current and temperature Stick-on sensor has been designed, fabricated and operated using a novel power circuit developed in this research.;As the Stick-on sensor uses an open ferromagnetic core-coil assembly for current sensing, it is prone to errors from other current carrying assets that produce far-fields, which interact with the sensor. Further, a change in the position of the sensor relative to the asset causes a change in its characteristics. Therefore, the sensor needs expensive calibration at the time of installation. This research develops novel current sensing algorithms that help the sensor to autonomously calibrate and makes the sensor immune from far-fields and crosstalk. The current sensing algorithm has been implemented and tested in the lab at up to 1000 A current.;Further, a novel self-calibrating low-cost voltage sensing technique is also developed. The major purpose of voltage sensing is detection of sags, swells and power loss on the asset; therefore, the constraint on error in measurement is relaxed. The technique has been tested through several simulation studies. Further, a voltage sensor prototype has been developed and tested on a high voltage bus at up to 35 kV.;Finally, this research also presents a study of sensor operation under faults, such as lightning strikes, and large short circuit currents. These studies are conducted using simulations and actual experiments. Based on the results of the experiments, a robust protection circuit for the sensor is proposed. Issues related to the corona and external electrical noise on the communication network are also discussed and experimentally tested. Further, a novel design of package for the sensor that prevents the circuitry from external electrical noise but prevents attenuation of power signals for the energy harvester is also proposed. |
