Energy consumption management using programmable logic controllers (PLC's)

One of the main challenges that encounter modern building industry is to reduce the overall electrical and fossil fuel energy consumption without affecting the quality of life of its residents, and at the same time complying with international environmental standards. The purpose of energy efficient systems is to control energy consumption and to reduce the negative impact on the surrounding environment through an efficient management of available energy resources, including renewable and nonrenewable resources. The management and integration of mains and solar power supplies, besides other available energy resources are the key elements for designing an efficient energy management system. In this paper, the usage of Programmable Logic Controllers (PLC's) is proposed to control the energy consumed by various loads in residential and commercial buildings, based on real-time measurements of certain factors affecting the total amount of consumed energy. Hence, this paper presents a real time prototype design and implementation of an automated control system for distributing electrical energy to various loads, using Allen Bradley MicroLogix 1100 Programmable Logic Controller (PLC). The PLC is programmed using ladder diagram for intelligent switching of both solar power supply and diesel generator power supply units, while giving the priority to solar energy as much as possible. The Rockwell Software Logix 500 is used for programming the PLC, running on a host computer terminal.