【作者】 刘春明；

【导师】 王泽忠； 刘连光；

【作者基本信息】 华北电力大学（北京） ， 电工理论与新技术， 2009， 博士

【摘要】 地磁感应电流(GIC)对电力系统的安全运行产生不利影响。本论文在国家自然科学基金项目(50677020特高压电网地磁感应电流评估模型和算法研究)的支持下,从实际测量和建模计算两个方面系统研究了中低纬电网GIC的特征和影响因素,提出了适合中低纬度电网的GIC评估方法,并对西北750kV规划电网的GIC水平进行了评估。主要研究内容如下:(1)通过对我国电网中发现的GIC影响事件和监测数据进行分析研究,发现我国虽然处于中低纬度但磁暴确实可在电网中产生较大幅度的GIC,可能对电网安全运行构成威胁。随着电网的发展和下一个太阳活动高峰期的来临,预测电网遭受GIC危害的风险将进一步增大,对我国电网GIC问题进行研究是必要和紧迫的。(2)对多次磁暴发生时采集的变压器中性点直流监测数据和磁暴数据进行对比分析、相关分析和统计分析,首次获得了中低纬电网GIC的特点和规律。发现地磁场水平分量变化率、大地电性结构、电网结构与参数是电网GIC幅度的主要影响因素,并且随着中低纬地磁活动的减弱,大地与电网特性对GIC的影响更为显著。(3)建立了均匀媒质和一维层状媒质中大地感应电磁场模型,提出了基于磁暴数据和大地电性结构参数的地面感应电场计算方法。以肇庆磁暴数据为依据计算了岭澳核电站变压器中的GIC,计算结果与实测数据符合较好,精度优于文献中高纬地区的计算结果,而且所需数据少,计算更简便。(4)建立了基于GIC准直流特性的电网主要元件等效模型,提出了计算GIC的电网建模方法和简化方法,推导了便于计算的矩阵方程解法,在此基础上讨论了电网结构与参数对GIC水平的影响。计算了江苏500kV电网上河变电站的GIC,获得了与实测数据相吻合的计算结果。(5)提出了应用分区大地电阻率模型和磁暴数据插值的方法消弱大规模电网GIC计算中因大地电导率和空间电流分布不均匀引起的误差。建立了2012年西北750kV电网GIC模型,给出了电网及变压器GIC水平评估结果,并对GIC可能对电网产生的影响进行了讨论。(6)提出了电网GIC以及引发的谐波、无功变化、振动、噪声等次生现象的监测方法,开发了相应的测量装置,获得了国家发明专利。试验结果显示监测装置的功能与性能符合设计要求。目前已在多个变电站安装运行并组成了电网GIC监测系统。更多还原

【Abstract】 Geomagnetically Induced Currents(GIC) will threaten safe operation of power systems. In this paper,supported by National Nature and Science Fund(Project No:50677020, Study on Evaluation Model and Algorithm of GIC in UHV Power Grid),from two aspects of actual measurement and modeling calculation,characteristics and effect factors of GICs in mid-and-low-latitude power grids is investigated,and GIC evaluation method applicable for power grids in mid-and-low latitude regions is proposed,and GIC level in Northwest 750kV Planning Power Grid is estimated.The main research content is as follows:(1) Through study on GIC related events and monitoring data in Chinese power grids, although China is located in mid-and-low latitude,magnitude of GICs in power grids is high enough to threaten safe operation of power grids.Moreover,with developing of power grids and approaching of next peak solar activity cycle,the risk that power grids suffer from GICs will increase enormously,thus it is necessary and urgent to investigate GIC in Chinese power grids.(2) DC current monitoring data collected from neutral points of some transformers and geomagnetic storm data during many geomagnetic storms are performed comparative and relevant and statistical analysis sequently.The result shows that variation rate of horizontal geomagnetic component,conductivity of the earth and topology & parameters of power grids are main influencing factors,of which with weakening of geomagnetic activities in mid-and-low latitude regions,characteristics of the earth and power grids are more important influencing factors to GIC magnitude.(3) Fundamental equation of earth induced electromagnetic field is deduced,the relationships between electric and magnetic fields in uniform medium and one-dimension layered medium are established respectively,calculation method of earth surface electric field based on geomagnetic storm data is put forward.Then Zhaoqing geomagnetic storm data taken as scenario condition,GIC in Lingao Nuclear Power Station is calculated.And the calculated result matches well with measured data.It is obvious that the method has merits like better precision than that in high latitude regions,and less data requirement,and more convenient calculation.(4) Based on quasi-dc characteristic of GIC,equivalent models of components in power grids are set up,and power grid modeling and its simplification method are brought forward, and matrix equation solution in convenience of calculation is deduced.Then Jiangsu 500kV Power Grid taken as a case,GIC in Shanghe Substation is calculated,of which the result proves the validity of model and algorithm compared with measured data.(5) GIC level in Northwest 750kV Planning Power Grid under the effect of uniform electric field and strong geomagnetic storm is estimated.The result shows that during strong geomagnetic storms GICs flowing in most of transformers exceed allowable threshold value, which needs enough attention from relevant departments.With application of earth resistivity divisional model and geomagnetic storm data,spatial interpolation method diminishes errors caused by the disequilibrium of earth conductivity and spatial current distribution when calculating GICs in large-scale power grids. (6) The monitoring technology of GICs in power grids is investigated,and a monitoring devlce,for which National Patent is authorized,has been developed.The devices can monitor not only GIC but operating parameters of transformers under the effects of GICs.The experiment result shows that functions and performance of monitoring devices meet all design requirements.Nowadays,GIC monitoring devices have been installed and operating in many substations and constitute a GIC monitoring system of power grids.更多还原