[论文解读] Flexible unit commitment of a network-constrained combined heat and power system

Alvaro González-Castellanos, Priyanko Guha Thakurta+1 more|arXiv (Cornell University)|Sep 25, 2018

Integrated Energy Systems Optimization参考文献 20被引用 3

一句话总结

本文提出了一种用于网络约束型联合电力与热力（CHP）系统日前灵活机组组合的混合整数线性规划（MILP）模型，整合了电力与热力网络，采用详细的CHP机组建模、蓄热系统以及直流潮流约束。主要贡献在于证明了热力与电力系统的联合运行可显著提升运行灵活性、效率与经济性能，尤其在利用蓄热系统并遵守网络约束条件下效果更明显。

ABSTRACT

Large Combined Heat and Power (CHP) plants are often employed in order to feed district heating networks, in Europe, in post soviet countries and China. Traditionally they have been operated following the thermal load with the electric energy considered as a by-product, while the modern trend includes them in the electric market to take advantage of the flexibility they could provide. This implies the necessity to consider the impact on the electric grid while filling the thermal load requests. A detailed Mixed Integer Linear Programming (MILP) optimization model for the solution of the network-constrained CHP unit commitment of the day-ahead operation is introduced. The developed model accounts for lossless DC network approximation of the electric power flow constraints, as well as a detailed characterization of the CHP units with useful effect, heat and power, function of one and two independent variables ("degrees-of-freedom"), and thermal energy storage. A computational validation of the outlined model on a CHP test system with multiple heating zones is presented in the form of computational test cases. The test cases illustrate the impact on the flexibility of the implementation of the energy storage, network constraints and joint multi-system operation. The conducted studies have highlighted the importance of a comprehensive and integrated analysis of multi-energy systems to exploit the operational flexibility provided by the cogeneration units. The joint operation of the thermal and electric system allows to reap economic, operational efficiency, and environmental benefits. The developed model can be easily extended to include diverse multi-energy systems and technologies, as well as more complex representations of the energy transmission networks, and the modeling of renewable energy resources dependent of one or more independent, weather-related, variables.

研究动机与目标

• 开发一种用于网络约束型CHP系统日前机组组合的综合优化模型。
• 将详细的CHP机组特性与一个或两个独立变量（如燃料输入与电/热输出）相结合，以实现精确建模。
• 通过直流潮流模型引入热能储存与网络约束，以增强系统灵活性。
• 评估蓄热、网络限制及多系统联合运行对运行灵活性与成本效率的影响。
• 通过模块化建模，实现向多能系统与可再生能源集成的可扩展性。

提出的方法

• 为具有网络约束的CHP系统日前机组组合构建混合整数线性规划（MILP）模型。
• 采用无损直流潮流近似方法，通过线路电纳与节点电压相角变量建模输电线路的有功功率流动。
• 通过分段线性化方法对性能曲线进行处理，适用于具有一个或两个独立变量（如燃料输入与电/热输出）的机组。
• 引入二元变量表示机组启停、启动过程及最小运行时间约束，以准确刻画运行动态。
• 按区域建模热能平衡，包含热传递效率、储存损耗与区域储热容量。
• 通过共享的CHP机组将电力与热力系统集成，确保负荷平衡与线路热极限约束。

实验结果

研究问题

• RQ1 在考虑网络约束的条件下，热能储存的引入如何影响CHP机组组合的灵活性与成本？
• RQ2 网络约束（如线路潮流限制）在多大程度上限制了联合热电系统中CHP机组的运行灵活性？
• RQ3 与独立运行相比，电力与热力网络的联合运行在提升系统效率与经济性能方面有何优势？
• RQ4 在机组建模中采用两个独立变量（如燃料与电/热输出）相较于单变量建模，对解的精度与灵活性有何影响？
• RQ5 所提出的MILP模型能否有效扩展以包含可再生能源与更复杂的多能系统配置？

主要发现

• 热能储存的集成显著提升了系统灵活性，通过实现热能转移，减少弃热，并降低运行成本。
• 网络约束（如线路潮流限制）对机组组合决策有明显影响，尤其在输电阻塞区域，必须显式建模以实现准确经济调度。
• 电力与热力系统的联合运行可显著提升运行效率与经济效益，使CHP机组能更有效地平衡电力与热力市场。
• 在机组建模中采用两个独立变量（如燃料与电/热输出）可更准确地反映CHP性能，从而提升解的保真度。
• 模型验证表明，热能储存损耗（假设为每小时2%）与热传递效率（92%）是影响系统性能与成本的关键参数。
• 在多区域CHP系统上的计算验证表明，该模型能够有效处理复杂的系统交互，实现最优且灵活的经济调度。