Direct load control using programmable logic controller

For many utilities, it is more cost effective to fully utilize what they have rather than try to build new power plants. More and more utilities are extending their activities into the customer's side. They are implementing the Demand Side Management (DSM) programs. The electricity distribution companies use either the Direct Load Control (DLC) or the indirect load control. There are different systems to apply the DLC. However, these systems suffer from shortcomings. A new DLC system is proposed in this thesis to overcome the drawbacks of the existing systems.; A new DLC system is designed in this thesis. It is proposed to use this system as one of the alternatives of the DSM programs. The proposed DLC system satisfies the utility objectives and the customer requirements.; The system has three main parts. The first part is a master station center at the utility side. It consists of a PC. The second part is the control device that is installed at the customer side. It is a Programmable Logic Controller (PLC). The third part is the interface circuits between the control device and the PC, and between the PLC and the loads. Two sophisticated programs are developed to serve the purpose of the proposed DLC system. One is stored in the PLC to direct control the customer loads. The other is used as user interface and PC protocol to control the installed PLC at the customer side. The control strategy is done through different scenarios. (Abstract shortened by UMI.)...