Application Of Particle Swarm Optimization PID Control On Variable Air Volume System

Nowadays global energy is increasingly scarce，and air-conditioning system is receivingmore and more attention as one of the most consuming energy appliances in buildings. VAVair-conditioning system has already achieved greater progress in the western developed countriesfor its vast potential energy since1980s. Although VAV air-conditioning system’s application andresearch has been undertaken in our country since1990s, it has already made considerableprogress in this area. While the pressure-independent terminal system has become the hotspot inrecent years by its more effective adjustment method and more energy conservation. Thepressure-independent terminal system adopts a cascade control system, but there hasn’t been asimple and highly effective method in the cascade system parameter’s determination. There aresome issues in conventional design method of closed-loop characteristics as expected, such asunitary thinking, and lack of fitness in main and auxiliary circuits, which cause that the systemcannot suppress effectively disturbance in main and auxiliary circuits at the same time, whichaffect the comfort and energy saving effect of variable air volume systems to a certain extent.In recent years, along with various intelligent algorithms’ development, researchers havealready combined neural networks and genetic algorithm with conventional PID control in orderto obtain the better control effect. Particle Swarm algorithm is one of faster developingalgorithms among intelligence algorithms, which is simple and efficient and has an advantage ofstronger seeking capacity. Conventional PID control parameters determine difficultly, and itoften requires a certain amount of controlling experience, and it usually adopts the method oftrial and error or by changing individual parameters to determine. These conventional methodsare inefficient and have weak ability of disturbance suppression, and thus they can not achieveideal controlling effect. This paper focuses on the shortcomings of conventional PID control, andapplies DPSO-CF to PID control. By making use of characteristics of particle swarmoptimization’s seeking merit automatically, it makes control systems complete controlrequirements automatically according to form of disturbance or strength by itself. On the basis ofmodeling VAV terminal units system, the paper has a study on the method of combining the PSOwith conventional PID control and has further completed the cascade controller’s design of VAVpressure-independent terminal units. Confirmed by the computer simulation, the controller hashigher adaptability, and it can suppress effectively disturbance in the main and auxiliary circuit,thus it has provided one kind of new method for the pressure-independent terminal’s design.