Dynamic Modelling and Control Design for Organic Rankine Cycle

Abstract

Organic Rankine Cycle (ORC) systems are able to utilize low-temperature heat sources, such as geothermal reservoirs, to generate power. One aim of the Above Ground Geothermal and Allied Technologies (AGGAT) programme is to develop an ORC manufacturing industry in New Zealand. The control system which regulates the plant is a key component of any ORC system. For effective control of an ORC system, it is important to develop an understanding of the dynamic behaviour of an ORC system and its various components. However, in many situations it can be impractical to perform testing on a real plant as it may compromise plant safety.
Instead, this paper endeavours to use simulation models as a means to aid plant and control design, overcoming the limitations of practical testing on a real operating plant. A dynamic simulation model of an ORC plant was built using a commercial flowsheet simulator, VMGSim. The dynamic behaviour of the plant was studied under a variety of step tests and process disturbances. This paper describes the results of these simulations and their implications on the design of control systems and plant operating procedures.