Simulation study on scroll expander digital electro-hydraulic governing system

Organic Rankine Cycles are particularly suitable for recovering energy from low-grade heat sources. Scroll expander has all the advantages of a scroll machine and is suitable to be used in ORC system. As the key element of the ORC, its safe operation has a direct relationship with all the system. Based on deep research on scroll expander´s working process, first the paper establishes dynamic mathematical model of scroll expander and designs scroll expander governing system depending on system requirements. The digital electro-hydraulic governing system is a nonlinear system, the control strategy choose only PID control can not achieve satisfactory control performance. Then the paper uses NCD module to optimize PID parameters. The simulation results indicate that this control method not only can improve the dynamic and static performances of the system, but also has better robustness.