Nonintrusive Load Monitoring (NILM) Module

João Mendes das Neves Martins

Key information

Authors:

João Mendes das Neves Martins (João Mendes das Neves Martins)

Supervisors:

Gonçalo Nuno Gomes Tavares (Gonçalo Nuno Gomes Tavares)

Published in

June 24, 2025

Abstract

This document presents the design and validation of a complete Nonintrusive Load Monitoring (NILM) module for monitoring single-phase residential energy consumption. The developed prototype acquires, processes, and transmits high-resolution electrical signatures from a single measurement point, enabling appliance-level identification without intrusive sub-metering. The hardware is a compact DIN rail-mounted module integrating an ESP32-WROOM-32E microcontroller and STPM32 energy metering integrated circuit on a custom four-layer PCB, ensuring signal integrity and electrical safety. The FreeRTOS-developed software manages concurrent tasks that include data acquisition, feature extraction, and Wi-Fi communication. Key electrical parameters such as RMS voltage, RMS current, active power, reactive power, apparent power, phase difference, and power factor are continuously acquired and transmitted to a cloud system that uses Node-RED, InfluxDB, and Grafana, enabling real-time visualization and reliable data storage. A proof-of-concept machine learning model was implemented to classify appliances according to their signatures. Labeled data for a washing machine, fridge, electric kettle, and idle “no appliance” state were collected and used to train a fully connected neural network, achieving 96\% test accuracy. Validation involved controlled tests with laboratory loads and real-world appliances, confirming accurate signature capture, reliable phase tracking, and stable data transmission. This work demonstrates a cost-effective and practical NILM module ready for deployment, capable of enabling appliance-level insights to support advanced disaggregation algorithms and energy-saving strategies, ultimately contributing to smarter and more sustainable residential energy consumption.