【作者】 张志强；

【导师】 袁荣湘；

【作者基本信息】 武汉大学 ， 电气工程， 2019， 博士

【摘要】 随着特高压交流和直流工程的发展,我国已经形成华北-华中特高压交流弱同步联网格局,伴随着天中、祁韶特高压直流接入,具有跨区互联大电网属性的华中电网又兼具了直流送受端的特性,而锦苏、复奉和宾金特高压直流的接入使得西南电网成为大送端电网,渝鄂背靠背直流投运将华中-西南的同步互联特性转变为异步互联特性。因此,论文以跨区互联大电网为主要研究对象以及工程实用化背景,针对同步互联型电网和异步互联型电网发生特高压直流闭锁故障后,所引发的频率稳定问题、电压稳定问题和失步振荡问题分别进行了深入研究,同时论文区别于传统独立的稳控系统,提出了多资源协调紧急控制系统的架构,并进行了实用化应用。论文的主要研究内容如下:(1)论文针对高频切机方案零基础的跨区互联大电网,提出了一种基于单机单负荷模型跨区互联大电网高频切机方案快速配置方法。首先,通过推导跨区互联电网解列后系统频率波动特性的解析式,在考虑系统备用及调速器作用情况下,得到系统频率动态特性曲线;其次,研究了负荷模型、负荷有功频率因子及调速器特性对系统频率变化的影响,构建频率影响相关性因子,量化并明确了这三个为频率特性主要因素;随后,基于跨区互联大电网高频切机实用配置原则,构建单机单负荷模型,快速配置高频切机各项参数定值,包括频率阈值、时间延时、最小切负荷量、每轮次切负荷比例等,最后通过大电网全模型的验证微调,方案实用化后效果良好。(2)论文计及跨区互联大电网的多种故障场景,构建了跨区互联大电网多场景多目标低频减载优化模型。首先,明确了跨区互联大电网在切负荷量和稳态频率恢复效果两方面存在优化的空间;其次,鉴于低频减载方案中可优化的变量非常多,依据减少负荷损失的优化目标,确定了优化变量为基本轮次和特殊轮次各轮的切负荷比例;随后,确定了目标优化函数,将平均切负荷量和平均频率偏差两个指标作为目标函数;同时,将负荷过切率、频率动态波动限制范围、稳态恢复频率和恢复稳态频率所需时间作为约束条件,再结合引起跨区互联电网低频问题的多个故障场景,基于NSGA-II算法,进行优化计算,为优化低频减载策略提供理论指导,以实现负荷损失及平均频率偏差双降的目标。(3)论文基于两机模型的本地量运行轨迹及振荡中心迁移规律,提出了一种跨区互联大电网失步振荡解列定值配置策略优化方法。首先,构建了两机模型,推导了基于本地量的失步解列判据机理,得到了测量点电压、阻抗、相角以及振荡中心电压的运行轨迹;其次,通过解列装置动作原理和发电机保护三阻抗原理的比对,建立了阻抗角原理和振荡中心电压原理的振荡解列装置仿真模型,优化了解列装置动作的仿真准确性;随后,通过分析电网振荡中心连续性迁移、大范围跃迁等电网振荡中心迁移规律,及切机、切负荷和系统解列等因素对振荡中心迁移的影响,提出了跨区互联大电网省间断面失步解列装置连锁动作的优化调整配置。(4)基于跨区互联大电网的频率、电压和失步紧急控制技术,提出了完善第一道防线、拓展第二道防线、优化第三道防线的系统保护架构,提出了多资源协调紧急控制系统的配置方案,并在系统保护实施初期提出了具体的多资源协调控制系统的整体建设方案。更多还原

【Abstract】 With the development of UHV AC and DC projects,China has formed the North China Central China UHV AC weak synchronous network pattern.With the access of Tianzhong and Qishao UHV DC,the central China Power Grid with the characteristics of cross regional interconnection and large grid has the characteristics of DC transmission end.The access of Jin Su,Fufeng and binjin UHV DC makes the southwest power grid a large transmission end power grid,Chongqing The back-to-back DC operation of Hubei province transforms the synchronous interconnection characteristics of central and southwest China into asynchronous interconnection characteristics.Therefore,based on the cross regional interconnected power grid as the main research object and the background of practical engineering,this paper studies the frequency stability,voltage stability and out of step oscillation caused by the UHVDC blocking fault of synchronous interconnected power grid and asynchronous interconnected power grid.At the same time,different from the traditional independent stability control system,this paper puts forward multi resources.The architecture of the source coordination emergency control system is applied in practice.The main contents of this paper are as follows:(1)In this paper,a fast configuration method based on single machine single load model is proposed for the over-frequency tripping generator scheme of cross region interconnected power grid without the scheme.First of all,by deriving the analytical expression of the frequency fluctuation characteristics of the system after the disconnection of the cross regional interconnected power grid,the dynamic characteristic curve of the system frequency is obtained under the condition of considering the function of the system standby and the governor;secondly,the influence of the load model,the active frequency factor of the load and the governor characteristics on the frequency change of the system is studied,the frequency influence correlation factor is constructed,and these three factors are quantified and defined It is the main factor of frequency characteristics;then,based on the practical configuration principle of high-frequency cut-off of cross regional interconnected large power grid,a single machine single load model is constructed to quickly configure the fixed values of various parameters of high-frequency cut-off,including frequency threshold,time delay,minimum cut-off load,load ratio of each round,etc.Finally,through the verification and fine-tuning of the whole model of large power grid,the practical effect of the scheme is good.(2)In this paper,a multi scenario and multi-objective low-frequency load shedding optimization model is constructed,taking into account the various fault scenarios of the trans regional interconnected power grid.First of all,the optimization space of load shedding and steady-state frequency recovery effect of cross regional interconnected large power grid is clarified;secondly,considering that there are many variables that can be optimized in the low-frequency load shedding scheme,the optimization variables are determined as the load shedding ratio of basic and special rounds according to the optimization objective of load loss reduction;then,the objective optimization function is determined to average At the same time,the load cut-off rate,the limit range of frequency dynamic fluctuation,the steady-state recovery frequency and the time needed to recover the steady-state frequency are taken as the constraints.Combined with multiple fault scenarios that cause the low-frequency problem of cross regional interconnected power grid,based on NSGA-II algorithm,the optimization calculation is carried out to provide the optimization of low-frequency load shedding strategy Theoretical guidance to achieve the goal of load loss and average frequency deviation double drop.(3)In this paper,based on the two machine model’s local operation trajectory and the law of oscillation center migration,an optimization method of out of step oscillation splitting constant value configuration strategy for cross regional interconnected large power grid is proposed.Firstly,the two machine model is constructed,the out of step splitting criterion mechanism based on local quantity is deduced,and the running track of measuring point voltage,impedance,phase angle and oscillation center voltage is obtained;secondly,the simulation model of oscillation splitting device based on impedance angle principle and oscillation center voltage principle is established through the comparison of action principle of splitting device and three impedance principle of generator protection The simulation accuracy of the operation of the train device is known.Then,by analyzing the migration law of the oscillation center of the power grid,such as the continuous migration of the oscillation center and the large-scale transition,and the influence of the factors such as machine cut,load cut and system disconnection on the migration of the oscillation center,the optimal adjustment and configuration of the interlocking operation of the out of step splitting device of the cross-section of the inter province interconnected large power grid are proposed.(4)Based on the frequency,voltage and out of step emergency control technology of cross regional interconnected power grid,the system protection architecture of improving the first line of defense,expanding the second line of defense and optimizing the third line of defense is proposed,and the configuration scheme of multi resource coordinated emergency control system is proposed,and the overall construction scheme of multi resource coordinated control system is proposed at the initial stage of system protection implementation.更多还原