Research On Load Feedforward Control Strategy Of Air Conditioning Water System Based On Delay Effect Analysis

The energy consumption of air conditioning system is a major part of building energy consumption.Air conditioning system optimization control is an important way to reduce energy consumption.The traditional PID control based on pressure difference and temperature difference has some shortcomings for the non-linear and large-delay central air-conditioning system.The traditional PID control method is not ideal for indoor comfort control and air-conditioning system energy saving.Chilled water system,as an important part of central air conditioning system,has a great influence on the total energy consumption of central air conditioning system.Therefore,a reasonable chilled water system control method is of great significance to the energy saving operation of central air conditioning system.This research takes the large space laboratory of Tianjin University as the research object.Firstly,The delay effect of the central air conditioning system is systematically analyzed and it is pointed out that the main delay is brought by the water flow.For the central air-conditioning chilled water system common adjustment methods,the delay time is divided into variable temperature control delay and variable flow rate adjustment delay to consider.The two kinds of delay are theoretically calculated and experimentally verified.The FLUENT numerical simulation of variable temperature control delay is carried out,which further verifies the accuracy of the theoretical algorithm.Based on TRNSYS and MATLAB software,a simulation platform of chilled water system was established for the ground source heat pump chilled water system in Tianjin University.Simulation of central air conditioning chilled water system in summer cooling conditions,compared with the actual test data to verify the correctness of the model.Respectively in the actual control,room temperature feedback fuzzy control and accurate load feedforward fuzzy control simulation.Comparing the simulation indoor temperature and the system energy consumption under the three control modes,the results show that the proposed precision load feedforward fuzzy control,while ensuring the best indoor comfort,compared with the actual control and room temperature feedback fuzzy control,the total energy consumption decrease by 14.1% and 9.2% respectively.