Study On Fuzzy Control For HVAC Chilled Water Systems

Variable primary flow chilled water system is an energy saving system. This paper outlines: (1) the basic components, (2) some popular controlling methods of chilled water systems, and (3) the application of constant temperature difference, constant pressure difference and terminal adjustment in detail. This paper also presents terminal adjustment and total differential temperature control, considering both stable operation of the chillers and distribution according to terminal need. At last, develops a relevant model between chillers in and out chilled water differential temperature and system flow. Especially points out that the gain of the model represents the total cooling consumption under different conditions.This paper introduces in detail the fuzzy control theory for large time delay and inertia process control. By summarizing, analyzing and integrating the traditional Mamdani Fuzzy inference systems, this paper presents a relative unitized fuzzy controller for easy debugging, application and popularization. With analyzing the effects of scale factors and proportional factors, concentrates most alteration in the two kinds of factors for designing dynamic variable parameter fuzzy controller easily.This paper investigates the effects of the intestine ingredients and scale and proportional factors in detail via systems simulation. And then integrates a fuzzy controller which has good characteristics of self-adaptive, robustness, stability and anti-interference. Aiming at the actual mutative load chilled water system, presents the variable scale factors fuzzy controller.The results show that this controller is better than the traditional ones in adapting to the mutative load of the system cooling consumption, and keeping the water differential temperature in and out chillers. It is profitable to reduce the energy conservation of the chillers and chilled water system. And the control strategy is simple and easy to be realized and suitable for the control of variable primary chilled flow water systems.