风机盘管系统最不利热力环路相平面模糊辨识

Phase plane fuzzy identification of the most unfavorable thermal loop in fan-coil unit systems

摘要:

为实现以最不利热力环路的末端支路压差作为控制参考量的变压差设定值优化控制方法,提出了最不利热力环路相平面模糊辨识方法并进行了试验验证.针对风机盘管变流量空调水系统,以空调房间热平衡方程为基础,建立了末端能量供需差值与室温同室温设定值偏差值e及偏差变化ec的数学模型,最不利热力环路为末端能量供需差值最大者.在e及ec组成的相平面中,末端能量供需能量差可由各相点S(e,ec)连成的相平面轨迹线特征反映. 依据模糊模式识别过程,以实时示踪方向向量角β_i及当前时刻室温与其设定值偏差e_i作为特征指标,以三角形函数为隶属函数,以最大隶属度原则为识别判断标准,制定了模糊识别规则表,确立了最不利热力环路的相平面模糊辨识方法. 最后,搭建了变流量空调水系统试验平台,各支路同步增大供水量,以期达到能量供需平衡的支路为试验辨识所得最不利热力环路,与上述方法辨识结果进行对比. 试验结果表明, 该辨识方法准确可靠,可辨识出系统中最不利热力环路.

Abstract:

To realize the optimal control of variable pressure difference in fan-coil unit systems, a phase plane fuzzy identification method was proposed and verified, which takes the terminal branch pressure difference of the most unfavorable thermal loop as the control variable. For fan-coil variable flow air conditioning water system, based on the heat balance equation of air conditioning room, the mathematical relations among the terminal energy difference between supply and demand, the deviation (e) between room temperature and its setpoint, and the deviation change (ec) were established. The most unfavorable thermal loop is defined as the one with the largest terminal energy difference. In the phase plane composed of e and ec, the terminal energy difference of the phase plane could be reflected by the trajectory characteristics of the phase plane connected by phase points S(e, ec). According to the fuzzy pattern recognition process, by taking the real-time tracer direction vector angle (β_i) and the room temperature deviation (e_i) as characteristic indexes, triangle function as subordinate function, and maximum subordinate degree principle as recognition criterion, the table of fuzzy recognition rules was formulated. The phase plane fuzzy identification method for the most unfavorable thermal loop was then established, and a test platform for variable flow air conditioning water system was built. The water flow of the branches was increased synchronously, and the branches that reached the balance between energy supply and demand are the most unfavorable thermal loops identified by the test. Experimental results show that the proposed method is accurate and reliable, which can be applied to identify the most unfavorable thermal loop in fan-coil unit systems.