A DDC-Based Integrated Electrical and Instrumentation Control System Architecture for Unconventional Oil Production Plants

Unconventional oil production plants are complex industrial systems characterized by harsh operating conditions, modular facility configurations, and tightly coupled electrical, instrumentation, and control subsystems. Conventional centralized control architectures, such as Distributed Control Systems (DCS) and Programmable Logic Controller (PLC)-based systems, often exhibit structural limitations in scalability, maintainability, and subsystem integration when applied to such distributed plant environments. This study proposes a Direct Digital Control (DDC)-based integrated electrical and instrumentation control system architecture for unconventional oil production plants from a systems engineering perspective. The proposed architecture adopts distributed field-level DDC controllers as autonomous system nodes, enabling direct processing of instrumentation signals and coordinated integration with electrical subsystems through a network-based structure. This transforms the control platform into a system-of-systems architecture in which process, electrical, instrumentation, safety, and supervisory layers operate as interoperable subsystems. The proposed system was implemented in a pilot-scale unconventional oil production plant to evaluate its practical applicability. The results indicate that the proposed architecture improves system scalability, modular adaptability, maintenance efficiency, and operational robustness compared with conventional centralized architectures. In particular, system expansion and module integration were achieved without structural redesign of the overall control platform. This study provides a practical architectural framework for integrated control of complex industrial plants and offers a foundation for future extensions toward smart plant operation, digital twin integration, and intelligent industrial system-of-systems engineering.