供热系统故障工况热响应特性与动态可靠性建模理论研究

In recent years, with the increase in elderly heating systems, the failure rate is increasing every year and the heating safety becomes more important. Existing heating systems require reliability theory urgently for their renovation and expansion. However, existing heating systems in China are not designed following a strict standard because of the lack of reliability design. Thus, the traditional reliability is invalid to evaluate the reliability of existing heating systems. A dynamic reliability method is put forward based on the dynamic characteristic of heating systems. First, the network under failure conditions is reconstructed by the valve net. Second, the thermodynamic model of heating systems is established by the theory of heat transport and storage in heating systems. Combining the hydraulic model under failure conditions and the control model, simulation is used to analyze the thermal response characteristics under failure conditions. The response characteristics and the rationality of the simulation model are verified by field and laboratory test. Finally, according to the dynamic characteristics under failure conditions, the state model and its stochastic process are formed to establish the dynamic reliability and the solving methods, based on continuous model and Monte Carlo simulation respectively. The dynamic reliability method breaks through the limitations of the traditional method. It is suitable for diverse existing heating systems, and provides theoretical support for improving the reliability design and safe operation standard of heating systems.

近年来随着高龄供热系统的增加，故障率逐年增长，供热安全问题广受关注，尤其是既有供热系统的改扩建迫切需求可靠性理论的指导。然而我国供热系统可靠性设计理论薄弱，既有系统的设计并未遵循严格的可靠性标准，传统可靠性指标难以对其有效评价。本项目提出一种基于系统运行动态特性的供热系统动态可靠性评价指标与方法。首先通过构造阀门网络重构故障工况管网，然后基于供热系统热量输送和蓄放热机理建立热力模型，联立故障工况水力模型和调控模型，通过系统仿真研究故障工况系统热响应特性。基于实验平台和现场测试研究，验证仿真模型的合理性和结果的可信度。最后根据故障工况系统的热响应特性构建状态模型及其随机过程，建立动态可靠度指标和基于连续事件模型与蒙特卡洛仿真的求解方法。动态可靠性研究方法突破传统方法的局限，适用于我国既有供热系统的多样性，为完善我国供热系统可靠性设计与安全运行标准体系提供理论支持。

我国供热系统设计缺乏有效的可靠性约束，导致既有供热系统的结构备用和输送能力备用先天不足。而传统的可靠性评价方法面向设计，考虑的变量不足，不适于评价既有和运行期的供热系统。本项目针对供热可靠性应用和研究的现状，提出直接以系统终端反馈——热用户室温作为供热可靠性评价的依据，避免了由热量或流量评价产生的偏差。为此，通过故障工况的拓扑重构，建立由水力模型、各组成部分热力模型构成的系统准动态热力模型，进而研究动态可靠性评价理论和模型，以解决既有和运行期供热系统可靠性评价时变量复杂、多变的难题。此外，供热运营企业故障记录的普遍缺乏和不规范导致了我国可靠性基础数据统计工作的进展缓慢，本项目提出采用基于结构可靠性理论的元件故障率仿真方法辅助数据统计。围绕上述研究内容，项目组通过理论分析、实验和仿真手段的结合，取得了如下主要成果：.（1）提出了供热管网的等效阀门网络和基于阀门网络的故障工况拓扑重构方法，构建了一套可用于故障工况仿真的供热系统准动态热力模型。.（2）提出了基于多种失效模式的直埋敷设供热管道故障率仿真模型，以及利用少量统计样本修正仿真故障率的贝叶斯方法。仿真数据与统计样本的结合，可解决目前元件故障统计样本缺乏的问题。.（3）建立了基于故障响应滞后的马尔科夫可修系统模型的动态可靠性评价方法，提出以热用户室温反馈为评价依据的热用户和系统可靠度指标。该方法和指标综合了运行时间、环境参数和系统热力特征等丰富的变量，适用于供热系统可靠性设计，以及我国复杂多样的既有供热系统可靠性评价。项目组开发的可靠性计算软件为推广热网可靠性设计提供了便利的计算工具。.随着经济水平的提升，供热安全问题已经成为该领域的热点。供热可靠性研究成果的应用将促进供热系统的可持续和健康发展。