Improvements in Fault Tolerance Characteristics for Large Chemical Plants Part I: Waste Water Treatment Plant with Decentralized Control

D. ZUMOFFEN; M. BASUALDO

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

AMER CHEMICAL SOC

Lugar: Washington, DC; Año: 2008 p. 5464 - 5481

0888-5885

A decentralized control scheme integrated with a recently developed Fault Detection, Isolation and Estimation system (FDIE) applied on a benchmark of Waste Water Treatment Plant (WWTP) is discussed here. This work belongs to a series which objective is to demonstrate quantitatively the achievable improvements on the fault tolerance characteristics supported by the integration with FDIE systems. In the previous work a decentralized structure applied on a larger benchmark as the Pulp Mill plant was presented. Specific aspects related with that case study were successfully handled by this methodology. Here the WWTP presents new scenarios based on faults occurrence and their incidence on the associated dynamic with this process. In this work faults such as extra dead time at actuators and bias in sensors which cause saturation are analyzed. Under these conditions a real need exists for turning the existent control scheme as Fault Tolerant (FT). It is done by the controllers reconfiguration using on line identification and Model Based Control (MBC) tools. As the main contribution of this paper a rigorous quantitative analysis is done accounting a complete set of simulation cases showing different scenarios. The accurate comparison study is given through several indexes associated with the WWTP benchmark and others useful for analyzing the methodology proposed here.