Model Predictive control; Renewable energy systems; organic Rankine Cycle.
Abstract :
[en] Organic Rankine Cycle (ORC) technology has demonstrated to be a suitable tool for
recovering waste heat at low temperatures. The fluctuating nature of the waste heat source (varying
temperature and mass flow) makes of waste heat recovery applications a challenging task. In this
contribution Model Predictive Control (MPC) and more classical PID-like controllers are investigated,
where special attention is paid to the analysis of the control performance for heat source profiles coming
from different applications. A dynamic model of a real regenerative ORC unit equipped with a single
screw expander developed in the Modelica language is used to test and compare the PID and MPC based
control strategies. Results show that for low amplitude variations PID and MPC can perform equally
good, but in case of large variations MPC is a more effective control strategy as it allows a safer and
more efficient operation, operating close to the boundary conditions where production is maximized.
