发电机定子单相接地保护及故障定位的研究

发布时间：2018-06-24 10:08

本文选题：发电机定子单相接地 + 选相　；参考：《华北电力大学(北京)》2017年博士论文

【摘要】：发电机发生定子单相接地故障时可能会灼伤定子铁心,甚至进一步发展成更严重的故障。此外,发电机组铁心结构复杂,铁心一旦损坏,修复困难,造成巨大的经济损失。论文以发电机定子绕组单相接地故障为研究对象,从定子单相接地故障选相、故障定位、双频注入式定子接地保护和选择性定子接地保护几方面进行研究。论文的主要工作与创新点如下:论文分析了大型隐极发电机的绕组电势相位特征,提出了两种计及绕组电势相位的绕组电势表达式。与传统的绕组电势表达式相比,所提出的绕组电势表达式计及了绕组电势的相位特性,为研究大型隐极发电机定子接地故障时电气量的相位特征提供了理论基础。论文提出了一种基于零序电压相位特征的选相新方法,提高了高阻接地故障时选相算法的灵敏度。新的选相算法充分利用了动作区域向顺时针偏转的特征,解决了低电压选相算法在高阻接地故障时灵敏度低且可能出现误选相的问题。理论和仿真分析表明:该选相方法适用于各种中性点接地方式,在高阻接地故障时也可以可靠识别故障相。论文提出了一种利用零序电压相位特征计算过渡电阻的新方法,进而实现了大型凸极发电机的定子单相接地故障定位。准确计算出故障时的过渡电阻是定子单相接地故障定位的最关键问题,论文发现了大型凸极发电机的零序电压相位与过渡电阻间的关系,实现了仅利用发电机的本体故障信号计算过渡电阻。对所提的故障定位方法进行了仿真分析和动模测试,结果表明:该方法适用于大型凸极发电机,在各种中性点接地方式下,定位结果准确,满足工程需要。论文指出大型隐极发电机的绕组电势相位会影响故障定位的精度,利用发电机的本体故障信号计算过渡电阻时必须考虑绕组电势的相位特征。论文计及了绕组电势的相位特征,对利用零序电压相位特征和相电压偏移特征的故障定位方法进行了改进。对改进前后的故障定位方法进行了仿真分析,结果表明:计及绕组电势相位特征后的定位方法,适用于大型隐极发电机,在各种中性点接地方式下,定位结果准确,高阻接地故障时同样满足要求。论文设计了一套双频率注入的定子接地保护方案,注入频率为20Hz和80Hz。此保护方案在发电机的起停机过程中不需要短时闭锁,实现了全过程的保护功能。高频段注入频率的选取是双频率注入的定子接地保护的重要问题,论文从注入式保护的灵敏度、滤波器参数设计等方面,对注入式保护的高频段注入信号的频率取值进行研究,确定高频段的注入频率选取为80Hz。论文提出了一种基于导纳不对称度参数的选择性定子接地保护新原理,解决了扩大单元接线机组定子接地保护无选择性的问题。论文分析了发电机定子接地故障时的导纳不对称度,对于故障发电机其导纳不对称度参数为“有”,其值大于1,非故障发电机其导纳不对称度为“无”,理论值为0。利用导纳不对称度参数构成的扩大单元接线定子接地保护,通过计算导纳不对称度的最大值找出故障元件。对所提出的方法进行了仿真分析和动模测试,测试结果表明该方法能够选出故障机组,灵敏度高。
[Abstract]:When the generator stator single-phase grounding fault occurs, it may burn the stator core and even further develop into a more serious fault. In addition, the core structure of the generator is complex, and once the core is damaged, it is difficult to repair and cause huge economic loss. Barrier selection, fault location, dual frequency injection stator grounding protection and selective stator grounding protection are studied. The main work and innovation points of this paper are as follows: the paper analyses the phase characteristics of the windings potential of large sapheno generator, and puts forward two kinds of winding potential expression of the winding potential phase, and the traditional winding electricity. Compared with the potential expressions, the proposed windings potential expression meter and the phase characteristics of the winding potential provide a theoretical basis for the study of the phase characteristics of the electrical quantity of the large sapheno generator stator grounding faults. A new phase selection method based on the zero sequence voltage phase features is proposed to improve the phase selection algorithm for high impedance grounding faults. The new phase selection algorithm makes full use of the characteristics of the movement area to clockwise rotation, and solves the problem of low sensitivity and misselection in high impedance grounding fault. The theory and simulation analysis show that the phase selection method is suitable for various neutral grounding modes and can also be used in high impedance grounding faults. A new method of calculating the transition resistance with zero sequence voltage and phase characteristics is proposed in this paper, and the stator single-phase grounding fault location of the large salient pole generator is realized. The accurate calculation of the transition resistance of the fault is the most important problem of the stator single-phase grounding fault location. The relationship between the zero sequence voltage phase of the machine and the transition resistance is realized, and the transition resistance is calculated only by using the fault signal of the generator. The simulation analysis and dynamic model test are carried out on the proposed fault location method. The results show that the method is suitable for large salient generator, and the positioning results are accurate and satisfied under the grounding mode of various neutral points. The paper points out that the phase of the windings of a large sapheno generator will affect the accuracy of the fault location. The phase characteristics of the winding potential must be taken into consideration when the fault signal is calculated by the generator's fault signal. The phase characteristics of the winding potential are taken into account, and the characteristics of the zero sequence voltage phase and phase voltage offset are used. The fault location method is improved. The simulation analysis of the fault location method before and after the improvement is carried out. The results show that the positioning method after the phase characteristic of the winding potential is suitable for large sapheno generator. The positioning results are accurate and the high impedance grounding fault meets the requirements. The stator grounding protection scheme with dual frequency injection, the injection frequency is 20Hz and 80Hz., the protection scheme does not need short time locking during the starting and stopping process of the generator. The protection function of the whole process is realized. The selection of high frequency injection frequency is the important problem of the stator grounding protection with dual frequency injection. The sensitivity of injection protection and filter are filtered. In the design of the parameter of the wave device, the frequency value of the high frequency injection signal of the injection protection is studied. It is determined that the injection frequency of the high frequency section is selected as the 80Hz. paper, and a new principle of selective stator grounding protection based on the admittance asymmetry parameter is proposed, which solves the non selectivity of the stator grounding protection of the extended unit connection unit. In this paper, the admittance asymmetry of generator stator grounding fault is analyzed, and the admittance asymmetry parameter of the fault generator is "there", its value is more than 1, the admittance asymmetry degree of the non fault generator is "no", and the theoretical value is 0. of the extended unit connection stator grounding protection, which is made up of admittance asymmetry parameter. The maximum value of the admittance asymmetry is calculated to find the fault element. The simulation analysis and dynamic model test are carried out on the proposed method. The test results show that the method can select the fault unit with high sensitivity.
【学位授予单位】：华北电力大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM31

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