Fault-Tolerant Control Strategy for Primary–Secondary Chilled Water System

Abstract

This chapter develops a fault-tolerant control strategy for secondary chilled water pumps, aiming at not only for eliminating the low delta-T syndrome and deficit flow problem but also for enhancing the energy efficiency of the chilled water distribution systems. This fault-tolerant strategy employs the developed flow-limiting technique that is activated when deficit flow tends to occur and eliminates it by resetting the differential pressure set-point for pumps control. This strategy also integrates optimal differential pressure set-point that can minimize flow resistance of chilled water loop while still satisfying cooling energy demand. The performance of this proposed strategy is evaluated in a simulated real-life environment representing a chilled water system in a super high-rise commercial building by comparing it with two conventional control strategies. Results show that the proposed strategy can effectively eliminate the deficit flow in the bypass at both starting and normal operation periods.