(724c) High Fidelity Dynamic Simulation of Integrated Process, Control and Electrical Systems

The practice of dynamic simulation involves the use of software programs that model the time dependent behavior of complex process systems using rigorous thermodynamic and first principles models that adhere to laws of conservation of momentum, mass and energy. The first dynamic process simulations were developed considering only the process and equipment involved so their functioning could be understood better to improve their design. As the use of such simulations broadened, the need to include process control behavior and interactions became a critical component. Having process simulations and controls together in one platform opened up a plethora of opportunities that ranged from designing and checking out controls to using the integrated system to train operators and evaluate what-if scenarios on the process as a whole. Further advancements in software technology have helped take these systems to a point today where a plant operator would find it difficult to differentiate between the experience on a Training Simulator from that in the real control room. The impact such systems have on improving plant availability and safety are well known. Clearly, over the past two decades, the methodology has gained wide acceptance as an effective tool in applications throughout various stages of a plant lifecycle from concept evaluation to design to commissioning, startup and operations.

The proposed paper discusses adding a third dimension to the technology by including electrical systems to the process and controls model. Electric drives are gaining more popularity today because of the various advantages it offers in terms of low maintenance, reduced emissions, ease of operation, lower lifecycle costs and increased availability. In addition they also offer improved flexibility of operations through the ability to control output power through variable frequency drives and they completely eliminate the impact of ambient temperature on equipment performance vis-a-vis a Gas Turbine driver. Industrial electric drives come in various sizes ranging from a few KWs to in excess of 60MW. Plants typically have in-house captive power plants to produce the power to drive these or in some cases they rely on public utility grids. As process plants are being driven towards increasing energy efficiency, the industry is also seeing an increase in the number of cogeneration plants being constructed. As such, large amounts of electric power generation and consumption have become key components of most large scale process plants. The process and electrical systems differ in their characteristics inherently as the time constants involved in the electrical system is typically much smaller compared to the ones on the process side. The systems however impact each other significantly to warrant analyzing them together. As an example, start-up or loss of a large driver could induce frequency and voltage fluctuations in the grid which could potentially impact other users and hence the overall stability of operations. Similarly loss of partial power generation or steam production, if not managed properly, could cascade into severe instabilities and even loss of entire operations.

The paper discusses the approach, benefits and value associated with integration of a first principles based dynamic model of electric power generation, distribution and consumption with a similar high fidelity dynamic model of the process and control systems. Example case studies will be presented to highlight the points the author intends to make.