Smart Metering of Variable Power Loads

Nonintrusive load monitoring (NILM) seeks to determine the operation of individual loads in a building strictly from measurements made on an aggregate current signal serving a collection of loads. Great strides have been made in performing NILM for loads whose operating state can be represented by a finite-state machine, i.e., loads that consume discrete or distinct power levels for periods of time. It is much more difficult to track the operation of continuously variable loads that demand ever-changing power. These loads are becoming more prevalent as variable speed drives, daylight-responsive lighting, and other power electronic controlled loads emerge on the grid. This paper demonstrates a method for tracking the power consumption of variable demand loads nonintrusively. The method applies to any site where NILM might be of interest, including commercial and industrial buildings, residences, and transportation systems.