近年来，燃气机组广泛应用，燃气发电已占据相当比例，这使得电力系统与天然气系统紧密地耦合在一起，系统的运行安全与彼此的运行状态息息相关。大规模天然气管网的慢动态特性给电-气耦合系统的安全控制提供了新的机遇。另一方面，大量的可再生能源接入电网，其出力的不确定性不但影响着电力系统的运行安全，还会通过燃气机组影响天然气系统的运行安全。目前尚未形成系统的针对耦合系统特点的安全分析及预警方法，也未有利用天然气系统慢动态特性提升电力系统安全水平的研究。本文在这一背景下基于多时间尺度提出了大规模电-气耦合系统安全预警与控制的理论和方法，主要工作总结如下：（1）提出了电-气耦合系统连锁故障预警预控的原理。研究故障传播及连锁故障的发生机理，利用天然气系统传输的慢动态特性提出了基于多时间尺度的连锁故障预警预控的原理和方法，定义了天然气系统故障的预警信号，并提出了电-气耦合系统综合运行状态分析及预警信号计算的模型和方法。（2）提出了天然气系统故障预警下电力系统的紧急控制策略。基于天然气系统的故障预警信号提出了电力系统紧急控制的动态优化模型及其简化求解方法，算例验证了所提控制策略对电力系统运行安全的提升效果及简化方法的有效性，同时分析了预警时间不足时燃气电厂储气装置的调控效果。（3）提出了电-气耦合系统多时间尺度综合安全评估及预防控制策略。提出了电-气耦合系统综合安全及安全评估的概念，定义了与时间相关的综合运行状态及行为指标。重点研究了综合预想故障分析，提出了加快分析速度的方法。按照模型及时间尺度的不同提出了静态综合安全评估和准动态综合安全评估。针对综合安全评估中预警时间不足的场景提出了计及预警安全约束的预防控制方法。（4）提出了计及预警安全约束的日前区间经济调度模型及方法。采用区间法建模可再生能源的不确定性，提出了电-气耦合系统的区间能流模型及其求解方法，分析了可再生能源不确定性对电-气耦合系统运行安全的影响。提出了区间预警的概念，并在此基础上提出了计及预警安全约束的日前区间经济调度模型及求解方法。
Recent years, on the one hand, the widespread use of gas-fired power plants couples the electricity system and natural gas system to a level that has never been reached before. As a result, the operational security of the two systems is closely related to each other's operating states. The slow dynamic characteristics of pipeline networks in natural gas systems provide new opportunities for the security control of electricity-gas coupled system. On the other hand, the large amount of intermittent renewable energy connected to the electricity system affects the security of the natural gas system through the gas fired power plants. At present, there is a lack of systematic security analysis and warning method that fully considers the characteristics of the two coupled systems. Additionally, little research has been conducted on slow dynamic process of natural gas system to enhance the security of electricity system.This thesis facilitates the theory and method of security warning and control of large-scale electricity-gas coupled system at multiple time scales. Main contributitions of this thesis includes:(1) The principle of security warning and predictive control of cascading failures in the electricity-gas coupled system is proposed. The mechanism of fault propagation and the occurrence situation of cascading faults is revealed. Then a principle of security warning and predictive control based on multi-timescale is proposed for the electricity-gas coupled system. The security warning signals of natural gas system failure are defined. Then the model and method of analyzing coupled system operating status and security warning signals are proposed.(2) An emergency control strategy is proposed for the electricity system with security warning signals of natural gas system failure. A dynamic optimization model is developed for the emergency control of the electricity system. A simplified engineering method is proposed to solve the optimization model. Case studies validate the effectiveness of the method and its effect in improving the operational security level. The application and function of gas storage devices are also discussed in scenarios when the available dispatch time is insufficient.(3) A multi-timescale security assessment and preventive control strategy for the electricity-gas coupled system is proposed. The concept of integrated security and integrated security assessment of the electricity-gas coupled system is proposed. A time variance performance index and comprehensive operation status is defined. A novel method is proposed to speed up the screening process of the pre-defined fault set. Static comprehensive security assessment and quasi-dynamic comprehensive security assessment are conducted at different timescales. A preventive control method consdiering warning security constraints is proposed, which addresses the scenario with insufficient available dispatch time.(4) A day-ahead interval economic dispatch method is proposed with taking into account warning security constraints. The uncertainty of renewable energy is characterized using the interval method. An interval energy flow model is proposed to quantify the influence of the uncertainty of renewable energy on the operation security of the electricity-gas coupled system. By introducing the interval warning security constraints into the interval model, a day-ahead interval economic dispatch model and its solution method are proposed.
