城市供水管道降-复压漏失机制及相机调控研究

Pressure management is a commonly used technique for reducing the leakage. Traditional rough pressure management is based on the idea that the leakage discharge is completely positively related to the pressure, and the only method of leakage control is lowering the pressure. Effect of pressure is not obvious without considering factors like pipe material, sequential variation of pressure, scheduling strategy. As a result, the existing pressure management measures have great limitations. Through pre-experiments, applicants found that the leakage discharge and the pressure is not simply positive correlated, under sequential variation of pressure. With the same pressure, the leakage discharge under the step-up process is smaller than that under the step-down process. Drop-restore mechanism is reducing the head and then quickly restoring the required head, changing the pipeline from a high-leakage state to a lower-leakage state, to achieve the purpose of reducing leakage quantity without changing average pressure. The applicant intends to research the mechanism through the experiment in depth, to study the impact of various factors on the leakage discharge. Bring the concept of discretional control into pressure management and build an optimal scheduling model according to the drop-restore mechanism. Then analyze its economic efficiency. According to the pressure and flow conditions in certain time of pipe, adjust the pump switch speed and pressure relief valve opening degree flexibly, changing the pipe network conditions, in order to reduce the leakage quantity without lowering the pressure. As a result,the potential of pressure relief leak is excavated to achieve optimal and discretional control.

压力管理是供水企业当前普遍使用的降低漏失技术手段。传统的粗放式压力控制基于漏失量与压力完全正相关思想，控制漏失的方法仅局限于单纯的降压；未考虑管材、压力逐时波动、调度策略等影响因素，导致压力管理成效不明显，所能应用的管网受限。申请者在实验中发现，漏失量与供水压力并非单纯的正相关关系，且有压力变化时序影响，同水压下升压过程的漏失流量比降压过程要小。管网降-复压调控即在不改变运行平均水压前提下，通过降低水压再迅速还原工况所需水压，将漏失量由较高状态转换为较低状态，达到漏失控制的目的。申请者拟通过实验深入探索管道降-复压与漏失量相关机理，探究上述各影响因素对漏失量的影响；引入相机调控的理念，构建降-复压优化调度模型，并分析其经济效能优劣。根据一定时段内管网压力、流量需求，灵活主动调节泵开关、转速和减压阀开度，以达到不降压甚至升压仍能降低漏损目的，以充分挖掘调压降漏潜力，达到优化相机调控目的。

供水管网的漏失控制需要精确的漏失流量-压力模型。本研究提炼出了漏失出流的水力学模型，总结了影响漏失流量-压力关系的影响因素，并在针对单一漏口进行研究，总结提炼了漏口面积、漏口形状、管材等因素对于单漏口漏失流量-压力关系的影响。研究发现黏弹性管道漏口面积与历史压力及该压力的施加顺序有关，并引入开尔文-沃格特模型，定量描述了黏弹性形变造成的漏口面积变化。通过有限元模拟及进行梯次升压、降压实验，验证了引入的开尔文-沃格特模型。通过管网实验的方法，将漏点随机均布在实验管网内，讨论了包含多个漏点的漏失流量-压力关系。在构建多漏点的漏失流量-压力模型后，利用该模型进行管网建模，为管网压力管理提供依据。最后，将得到的模型应用于实际DMA分区的现场实验，根据Y小区建立微观水力模型，并引入黏弹性漏失模型；利用最不利点压力实测值校核模型，使动态模型更加接近Y小区供水管网运行情况，研究发现的漏点升压过程漏失流量普遍小于降压过程漏失流量，由此引入的实现降-复压漏失控制，实现了在不显著降低供水水头的前提下降低物理漏失，未来可以推广到没有降压空间的管网压力管理实践中。