Design and Implementation of a Programmable Load Shedding System with Wireless Remote Terminal Unit for Power Distribution Networks

Electric power distribution networks in many developing regions continue to suffer from chronic instability caused by feeder overloading, voltage fluctuations, weak automation infrastructure, and limited supervisory control. Rural and semi-urban feeders are particularly affected, where manual load shedding remains the dominant mitigation strategy despite its slow response time, operational inefficiency, and susceptibility to human error. Conventional SCADA- and PLC-based automation systems offer high reliability but are often financially and infrastructurally impractical for low-resource environments. This paper presents the design, implementation, and experimental validation of a low-cost, programmable load-shedding system based on a microcontroller-based RTU–CCMU architecture with hybrid wireless communication. The proposed system integrates IEC 61131-3–inspired deterministic control logic directly within an STM32-based RTU, enabling autonomous multi-stage load shedding and restoration based on real-time voltage and current measurements acquired from distributed CCMUs. A dual-channel communication framework is employed, combining ZigBee for low-latency operational control with GSM/GPRS as a wide-area supervisory and fallback channel, ensuring resilience in the event of communication failures. A complete hardware prototype comprising a Remote Terminal Unit (RTU) and a Central Control and Monitoring Unit (CCMU) was constructed and evaluated using a controlled laboratory testbed. Experimental results demonstrate sub-100 ms end-to-end load-shedding response times, with Stage-1 actions consistently below 50 ms, greater than 98% ZigBee communication reliability, and reliable GSM-based failover for supervisory control. Comparative benchmarking shows that the proposed system significantly outperforms GSM-only and LoRaWAN-based solutions while achieving near-PLC performance for feeder-level corrective actions at a fraction of the cost. The proposed architecture provides a practical and scalable pathway for deploying real-time distribution automation in infrastructure-constrained power networks. Keywords: Distribution Automation, GSM/GPRS, Programmable Load Shedding, Remote Terminal Unit, Smart Grids, ZigBee Adedokun G., Kehinde O.K. & Oyeniran O.J. (2026): Design and Implementation of a Programmable Load Shedding System with Wireless Remote Terminal Unit for Power Distribution Networks. Journal of Digital Innovations & Contemporary Research in Science, Engineering & Technology. Vol. 14, No. 1. Pp 9-36. www.isteams.net/digitaljournal dx.doi.org/10.22624/AIMS/DIGITAL/V14N1P2