【作者】 王琦；

【导师】 李扬； 汤奕；

【作者基本信息】 东南大学 ， 电气工程， 2017， 博士

【摘要】 随着智能电网建设的推进,大量传感设备、通信设备、计算设备和电气设备通过通信网和电力网两个实体网络互连,成为一个具备实时感知、动态控制和信息服务融合能力的多维异构复杂系统,即电力信息物理融合系统(Cyber Physical System,CPS)。在电力CPS环境下,多元广域信息的获取和利用为电网分析与控制决策带来了数据支撑,但同时也引入了信息通信网络失效的风险。本论文在国家自然科学基金(项目号:51577030)课题"电力信息物理融合系统的负荷预防-紧急控制理论与方法"资助下,针对电力系统受到大扰动后的频率暂态稳定问题,深入系统地开展了"电力信息物理融合系统的负荷紧急控制理论与方法"的论文工作,主要工作内容和创新包括:以电力CPS为研究对象,通过电力通信业务探寻电力系统和通信系统之间的交互影响机理;针对具体电力CPS负荷紧急控制业务,同时考虑广域信息的充分利用和广域通信的失效风险,提出能满足在线应用需求的频率态势预测方法和紧急控制策略;针对电力CPS领域仿真验证工具缺失问题,提出了电力CPS联合仿真方法并搭建了实时仿真平台。具体工作如下:(1)通过对电力CPS组成结构分析,得到电力物理层和信息通信层通过电力通信业务交互影响这一本质,提出通过中间业务脆弱性指标计算以评估电力CPS系统脆弱性的研究框架。本文以电力通信业务失效概率和失效后果综合评估其脆弱性:同时考虑受通信元件影响的电力业务传输主要路径和备用路径的中断和延时特性,并计及不同业务需求,提出电力通信业务失效概率的计算方法;同时考虑业务自身及所影响电力节点的重要程度,提出电力通信业务失效后果量化计算方法。基于电力通信业务脆弱性指标,考虑电力通信网络各节点和传输链路延时和中断属性对所承载业务脆弱性的贡献大小,提出电力通信网络的脆弱性指标计算方法;分别基于历史数据和实时数据提出电力CPS脆弱性静态和实时动态计算方法。(2)以电力CPS环境下支撑频率稳定的负荷紧急控制为研究对象,从频率态势预测和控制决策两方面展开研究。首先在电力CPS频率态势预测方面,针对基于模型或基于人工智能的快速预测方法在实时应用中的不适应性,本文力图探寻算法计算精度和速度的平衡。考虑到基于物理模型简化方法能够保留系统参变量间物理联系,但精度受限;而人工智能方法无法考虑数据间原有的模型联系,样本要求高;因此提出融合频率响应模型的极限学习机算法,在保证计算速度的前提下大幅提高预测精度。基于脆弱性评价方法,计算电力系统节点可观性;综合提出计及可观性频率态势特征预测方法。(3)在控制决策方面,依托实际的广域负荷紧急控制网络,提出可中断负荷快速响应主网频率稳定问题的算法。首先利用广域量测信息和频率态势特征精确预测结果,提出基于改进样本获取方式的极限学习机的精确切负荷预测算法;同时基于电力节点可中断负荷容量和信息通信链路特征,提出负荷节点紧急控制能力指标,用于切负荷量分配。该控制策略能够充分考虑系统多元信息,在保证切负荷代价最小的基础上兼顾策略有效执行。(4)无论是电力CPS理论分析或控制策略,现有单一的电力或通信仿真平台均无法提供较好的仿真支撑环境,因此提出混合仿真方法。在非实时仿真方法方面,从建模工具、系统架构和数据同步等关键问题角度对相关的研究成果进行了归纳分析,指出电力CPS系统的时间同步问题是混合仿真的关键问题之一;针对现有方案在无法兼顾仿真精度和效率的不足,提出了一种基于状态缓存的电力CPS混合仿真平台时间同步方法,为后续相关研究提供解决思路。在实时仿真方法方面,提出一种通用、易于再现的电力CPS实时仿真方案,该方案采用了 OPAL-RT、OPNET软件以及独立控制应用模块。所提方案主要针对电力CPS环境下负荷控制业务,并可以扩展用于各类型智能电网应用的实验验证。更多还原

【Abstract】 With the development of smart grid technology,large number of sensing devices,communication,computing and electrical power equipment are connected through the power grid and communication network to form a multi-dimensional heterogeneous complex system with the integration capabilities of real-time sensing,dynamic control and information services,which is cyber physical power systems(CPPS).Under the environment of CPPS,the acquisition and utilization of multiple wide-area information brings data support for power system analysis and control,but also introduces the risk of communication network failure.In this paper,funded by the National Natural Science Foundation(Theories and Methods for Load Preventive and Emergency Control of Cyber Physical Power Systems,51577030),focused on the frequency stability issues after large disturbance in power system,an in-depth study of theories and methods for load emergency control of CPPS is carried out.The main work content and innovation of this paper are as follow:taking CPPS as the research object,the interaction mechanism between power system and communication system is explored through the power communication services;focused on the specific load emergency control services,with consideration of both utilization of wide-area information and risk of communication failure,the frequency prediction method and emergency control strategy meeting the requirements of online application are proposed;a co-simulation method to support the studies in CPPS is put forward.The specific works are as follow:With the analysis of composition structure in CPPS,the fact that the power system and communication system are interacted through communication services is indicated,and a vulnerability assessment framework to assess the impact of communication system failures on wide-area electric power system operation is proposed.The original research contributions of this paper are that:1)both latency and interruption faults are considered probabilistically to assess the reliability of communication services;2)a multi-level analytic hierarchy process structure is adopted to quantify different impacts of communication services;3)the communication network failure is quantified as the contribution of components to services failure,which is used to illustrate the weakest section of the whole network.A case study of integrated power and communication systems is used to demonstrate the usefulness of the proposed framework.The proposed method can be used to evaluate the vulnerability of communication systems for electric power grids in both static and dynamic states.Taking the load emergency control supporting the frequency stability of power system as the research object,studies of frequency prediction and control strategy are carried out.In this paper,we try to find out the balance between the accuracy and computing speed of the algorithm based on the incompatibility of model or artificial intelligence-based fast prediction method in real-time application.The physical model-based simplified method can remain the connection between physical parameters,but the accuracy is limited;while the artificial intelligence method cannot consider the model connection of original data,and require samples of high quality.Thus,an extreme learning machine method integrated with system frequency response model is proposed to predict the frequency with the consideration of the observability of power nodes.In terms of control strategy,based on the wide-area load emergency control network,an algorithm of using the fast response capability of interruptible load to support the frequency of power grid is proposed.With utilization of the accurate prediction result and the improved sample acquisition method,a precise load shedding strategy is put forward.Then based on the capacity of power nodes and the corresponding communication path parameters,the emergency control capability index of power load nodes is calculated,which is used to dispatch the load shedding requirement.The proposed method can ensure the minimum cost of load shedding and the execution reliability.The event-driven discrete characteristic of communication system and the time continuous characteristic of power system make the researches in power and communication combined system more complex.Simplification of either system’s model should be processed during simulation using single simulation tool,which will bring negative impacts on the accuracy and practicability of the research results.The hybrid simulation platform,which can be used to analyse complex dynamic performance of power and communication combined system,has therefore become the research hotspot in recent years.To summarize the research findings in this field,unified simulation methods,non-real time simulation methods and real time simulation methods are discussed respectively.Simulation tools,system architecture and data synchronization problem are reviewed and analysed in detail,and the time synchronization problem is indicated as the key issue in hybrid simulation research.A new time synchronization method based on state cache is proposed to provide idea for further research.Based on power system simulation tool OPAL-RT and communication simulation tool OPNET,a real-time co-simulation platform for power CPS is proposed with originally developed data transmission interface and conversion module,which can simulate the dynamic characteristics of system precisely with high speed.A case study of load control system demonstrates the reasonability and validity of the platform.更多还原