Systematic analysis method of sensor and actuator faults propagation and impacts for optimally controlled complex building chilled water systems

Abstract

The effectiveness of the commonly used optimal control strategy of a secondary chilled water system usually suffers from the health conditions of numerous sensors and actuators involved. This paper presents a systematic analysis method of sensor and actuator faults propagation and impacts for optimally controlled complex building chilled water systems. Through fault modelling and fault injection, the proposed method aims to analyze the sensor and actuator fault propagation behaviours between the control strategy and the chilled water system. Case studies have shown the results that the errors of sensors and actuators significantly affect the pump control performance and indoor thermal environment. The pump control performance is more sensitive to three sensors: the supply air temperature sensor, the indoor air temperature sensor and the valve opening signal sensor of the terminal at the critical hydraulic loop. The indoor thermal environment is more sensitive to the indoor air temperature sensor. Compared to the baseline case without errors, the maximum deviation could reach 29.20% and 11.11% (in Celsius) for the chilled water pump energy consumption and indoor temperature respectively, under 10% error of related sensors. Actuator fault, like stuck valve, would result in a deviation of up to 42.46% in the pump energy consumption and up to 16.87% (in Celsius) in the indoor temperature. For applications, the proposed method is hoping to acquire general symptoms under various types of sensor faults for the fault diagnosis and contribute to enhancing the robustness of the optimal chilled water pump control strategy.