【作者】 张峥；

【导师】 林颐清；

【作者基本信息】 山东大学 ， 工程热物理， 2011， 硕士

【摘要】 随着集中供热的大规模应用,许多学者对集中供热系统进行了大量的研究,但是目前对集中供热系统整体实时性的研究较少,本文通过构建的仿真系统对供热管网进行了实时仿真,并对供热系统的优化调节及PID自动控制进行了研究。本文首先对将供热一次网分为热源、管道、节点、加热器、水泵等子系统,并针对各子系统分别建立数学模型：根据供热管网管道的特点,将其视为一元管道,然后对管道的流动、传热建立了求解方程；热网循环水泵采用了变频水泵,对其数学模型进行了推导和求解；建立改进的节点方程,对其的动态特性进行了研究；建立板式换热器的换热模型,并求解动态响应。随后,本文将各子系统有机地结合,组成了热网的整体实时仿真系统,对不同工况下的流动和换热进行了研究,并对供热系统事故的发生进行了讨论,仿真结果表明：当某一支路的流量发生大幅度变化时,其它支路可能会发生水力失调和热力失调等现象,因此必须限制支路流量的调节在一定范围内；在不同的工况下,由于工质的流动滞后性和传热滞后性,用户出口温度会出现峰值或谷值等不同的现象；当循环水泵和蒸汽加热器发生故障,停止工作时,由于管道、水、换热器等的蓄热作用,供热系统的加热作用需要经过一段较长时间才会逐渐消失,不过这种事故将会导致汽化等现象的发生；当节点发生泄露时,泄露位置的不同,各支路用户的流量和温度会出现上升、下降等不同的变化,这对于从运行变化上发现泄露是非常有帮助的。为了实现供热系统支路的自动控制,本文设计了基于二自由度的PID一次热网支路控制器,对PID参数进行优化整定,并使用MATLAB/SIMULINK进行了控制仿真。通过与普通PID调节的对比,发现二自由度PID控制器的调节更加准确,稳定性较好。在考虑管网热损失、漏水热损失等因素的情况下,本文建立一次热网运行能耗方程,对质调节、量调节以及质量并调三种热网运行调节方式进行了经济性比较；利用遗传算法对该能耗方程进行最优求解,得到了不同运行工况下的最优供水温度及相应的循环水流量。更多还原

【Abstract】 With the rapid development of the urbanization, District Heating System has play an even more important role in our life. Many researchers have done much for the DHS.Dynamic models of district heating systems are essential for simulation and control design. Subsystem models have to be developed for the heat source, pipelines, heat exchangers, and pump. The pipe can be regarded as one dimension and the equations for the heat transfer and flow of the pipe are evolved and resolved. The pump models adopt the variable frequency pump and the math model is deduced and resolved. The node equation is also constructed and the dynamic performance of the node is also studied. The math model of the heat exchanger is established and the dynamic response is also settled.The subsystems constitute the whole DHS simulation system. The variable flow and the heat transfer conditions are researched in the system. The impact of the leak of the node is also discussed. When the pump frequency changes or the flux in some pipe changes, the movement trend of other pipes is alike in the gross. When the frequency decreased, the temperature of the cycle water firstly rises and then fall down. Mean while the temperature of the nodes share the same trend. When the resistance is reduced in one pipe, the flux of others soars up.. the return water temperature increases and the supply water temperature of heat consumer also increased. When the leak of some node happened, the flux of out of pump get a raise and the temperature gets down if the temperature and the flux of heat source keep constant. The flow and the heat transfer far from leak point experience little influence. The flux of pipe near to the leak point decreased and the return water of heat exchanger and the supply water of the heat consumer decreased also when the pipe is in the front of leak point. When in the behind, the flux increased and the temperature also rise.To implement the automatic control of the branches of the district heating system, the two-degree-of-freedom PID controller is developed in this paper and the parameters are optimized too. MATLAB/SIMULINK is applied to simulate the new PID controller. Compared with the traditional PID, the new controller is more accurate and stable. With considering the thermal loss and the leak loss, the primary district heating system energy consumption equation is set up and the three regulation modes for the district heating system are compared for economic analysis. The GA is used to optimize and solve the equation to obtain the optimized supply temperature and supply water flow in different operation conditions.更多还原