Towards a general stability analysis of process network systems

This paper considers process systems whose dynamics are described by conservation laws for extensive variables and second law of thermodynamics and which can also been considered as interconnected (network) systems. In representing the dynamics and the analysis of network systems Tellegen's theorem and the passivity theory are used. Different from the usual application of these two methods on large scale systems, in this work, we only consider a single unit (node). For a single process unit, we apply the Tellegen's theorem and using a suitable storage function, derive the expression for the rate of change of the storage function. This expression is obtained for the cases of single phase and binary phases.</p

Model Predictive Control of Offshore Power Stations With Waste Heat Recovery

The implementation of waste heat recovery units on oil and gas offshore platforms demands advances in both design methods and control systems. Model-based control algorithms can play an important role in the operation of offshore power stations. A novel regulator based on a linear model predictive control (MPC) coupled with a steady-state performance optimizer has been developed in the simulink language and is documented in the paper. The test case is the regulation of a power system serving an oil and gas platform in the Norwegian Sea. One of the three gas turbines is combined with an organic Rankine cycle (ORC) turbogenerator to increase the energy conversion efficiency. Results show a potential reduction of frequency drop up to 40% for a step in the load set-point of 4 MW, compared to proportional–integral control systems. Fuel savings in the range of 2–3% are also expected by optimizing on-the-fly the thermal efficiency of the plant.</jats:p

Passivity-based nonlinear control of CSTR via asymptotic observers.

International audienceThis work makes use of a passivity-based approach (PBA) and tools from Lyapunov theory to design a nonlinear controller for the asymptotic stabilization of a class of non isothermal Continuous Stirred Tank Reactors (CSTR) around any desired stationary point. The convergence and stability proofs are derived in the port Hamiltonian framework. Asymptotic observers that do not require knowledge of reaction kinetics are also proposed for a system with incomplete state measurement. Numerical simulations are given to illustrate the application of the theoretical results to a CSTR with multiple steady states

An EnergyPlus whole building energy model calibration method for office buildings using occupant behavior data mining and empirical data

This paper proposes a method comprising procedures to calibrate an EnergyPlus whole building energy model. An occupant behavior data mining procedure is developed and tested in an office building. Workday occupancy schedules are generated by mining the office appliance energy consumption data. Hourly and monthly power, energy, and temperature data are collected and used for lighting, equipment and HVAC systems energy performance calibration. The result shows a 1.27% mean bias error for the total annual energy use intensity. The proposed calibration method provides a scientific and systematic framework to conduct high accuracy EnergyPlus model calibration