Fault tolerant control strategies for a high-rise building hot water heating system

Abstract

Improving energy efficiency and temperature control in hot water heating (HWH) systems are important considerations. The more challenging problem is to maintain good set point control under failure conditions. In this paper, model-based fault detection and diagnosis (FDD) and fault tolerant control (FTC) strategies were designed and simulated for a high-rise building HWH system. An overall system dynamic model with multiple control loops was developed. In the FDD methodology, fuzzy inference systems were employed to isolate the faults and evaluate the fault level. In the FTC strategies, error correcting function was defined consisting of set points, measurement and FDD information. A supply water temperature sensor fault and a multi-fault scenario consisting of heater efficiency fault combined with a partially blocked control valve fault were studied. Simulation runs showed that the developed FDD strategies isolated the faults and the designed FTC strategies were able to improve the system performance. Practical application: The performance of control systems is frequently degraded by the faulty sensors and actuators in hot water heating systems. By implementing the designed fault tolerant control strategies the hot water heating system can be operated to achieve higher energy savings both under fault free and faulty conditions.