Advanced nonintrusive load monitoring system

Abstract

There is a need for flexible, inexpensive metering technologies that can be deployed in many different monitoring scenarios. Individual loads may be expected to compute information about their power consumption. Utility providers, facilities managers, and other consumers will likely find innumerable ways to mine information if made available in a useful form. However, appropriate sensing and information delivery systems remain a chief bottleneck for many applications, and metering hardware and access to metered information will likely limit the implementation of new electric energy conservation strategies in the near future. This thesis presents solutions for two long standing problems in nonintrusive power and diagnostic monitoring. First, a high-resolution, physically windowed sensor architecture that is well-suited for energy score-keeping and diagnostic applications will be discussed. The sensor can track a large-scale main signal while capturing small-scale variations. The prototype system uses digital techniques to reconstruct an observed current with a high effective bit resolution. The sensor measures a small current signal using a closed-loop Hall sensor. and extends the range by driving a compensation current with a high performance current source through an auxiliary winding. The system combines the compensation command and the sampled output of the residual sensor to reconstruct the input signal with high bit resolution and bandwidth. Second, a long-standing problem in nonintrusive power monitoring involves the tracking of power consumption in the in the presence of loads with a continuously variable power demand. Two new techniques have been developed for automatically disaggregating, in real-time. different classes of continuously variable power electronic loads which draw distorted line currents. Experimental results of the proposed power estimator extracting the power consumption of common variable power loads such as a variable speed drive, a computer, and a light dimmer are presented.