Modified Nonintrusive Appliance Load Monitoring For Nonlinear Devices

Abstract

NIALM is a modern technique to know load profiles of individual appliances by monitoring the whole load at a single point by one recording device[5]. Each appliance has its own characteristics which results in a unique magnitude and sign in active and reactive Power as well as have unique frequency spectrum when it is switched on. Existing technologies use two dimensional signature space of real and reactive Power (DeltaP-DeltaQ Plane) for house hold appliances , while a three dimensional space with axes denoting real power ,reactive power and third harmonic is used in buildings for load monitoring[l]. During last decade , low cost power electronics devices and their efficiency have resulted into their increased use in household appliances, examples of house hold appliance using these devices are CFL , electronic chokes , AC inverter fed motors in washing machine, vacuum cleaner and appliances using variable speed motors etc. These devices are highly nonlinear which results in increased harmonics. These harmonics are used for load identification This research is focused on monitoring and analyzing current harmonics.. Then based upon analysis, frequency domain spectrum is used in combination with real and reactive power to identify nonlinear loads. So this research is focused on the development of appliance signature in frequency domain and time domain both In this way nonlinear devices are also identified. For this purpose current of CFL ,Dimmable fan , dimmable light are observed and their FFT is analyzed. After developing signatures, algorithm is also proposed for identification so that we could use it in real time applications.