摘要
抽水蓄能机组作为关键电气设备,其运行连续性与可靠性对构建新型电力系统意义重大。针对抽水蓄能机组励磁绕组匝间短路故障的状态监测易受动/静偏心及电枢反应影响,早期故障特征难以有效辨识的问题,该文提出一种基于环流时频图谱的励磁绕组匝间短路故障诊断方法。首先,根据抽水蓄能机组的结构特点及电磁感应关系,推导了动/静偏心及静偏心复合励磁绕组匝间短路状态下的同相多支路环流公式,得到了各状态下的环流特征谐波;其次,搭建了发电容量为334 MV·A的抽水蓄能机组二维有限元仿真模型,计算了动/静偏心及不同匝间短路程度下的同相分支环流大小,绘制了相应的时域、频域及时频图谱,通过对比实验验证了环流时频图谱可从时间、频率角度全面解析故障特征,有效区分偏心、电枢反应干扰与匝间短路故障;最后,基于凸极同步发电机模拟实验平台,模拟了不同故障程度的匝间短路运行状态,采集了同相支路电流数据用于环流时频图谱分析,实验结果证明了该方法可有效排除静偏心及电枢反应干扰,并以包含运行时间、特征频率及信号强度的三维图谱信息直观地展示机组的运行状态。
As key electrical equipment,the operational continuity and reliability of pumped storage units are significant to the construction of new power systems.During operation,the inter-turn insulation of the excitation winding is susceptible to deterioration due to multiple factors,such as unbalanced electromagnetic force,thermal stress,and external mechanical stress.It is important to quickly and accurately extract the early weak fault characteristics of inter-turn short circuits(ITSC)and organize timely condition maintenance.The condition monitoring of ITSC faults in the excitation winding is susceptible to dynamic/static eccentricity and armature response,and early fault characteristics are hard to identify.Therefore,this study proposes a fault diagnosis method based on a time-frequency circulating current(TFMCC)map.Firstly,this study derives the equations for the same phase multi-branch circulating current in the dynamic/static eccentricity and static eccentricity composite ITSC states,and obtains the characteristic harmonics of the circulating current in each state.Secondly,a two-dimensional finite element simulation model of 334 MV·A is constructed,and the magnitude of the same phase branch circulating current under each state is calculated.Comparative experiments have verified that TFMCC can effectively distinguish between eccentricity,armature reaction disturbance,and ITSC faults.Finally,based on the salient synchronous generator simulation platform,the operating conditions of ITSC with different fault levels are simulated.Simulation results show that changes in the dynamic/static eccentricity degree cause the time domain amplitude of circulating current changes,and the armature response and dynamic eccentricity also cause the appearance of characteristic fractional harmonics.Accordingly,ITSC fault diagnosis by a single-time domain analysis or spectrum analysis can easily lead to fault misclassification.The TFMCC allows the fault to be located at the moment of occurrence.The signal intensity at the characteristic frequencies(5.5,11,22,28,39,44.5 Hz)is significantly enhanced compared to the normal state.Meanwhile,a comparison with the dynamic/static eccentricity shows that the signal intensity of the dynamic eccentricity is mainly concentrated at 55.5 Hz,and the static eccentricity is mainly concentrated at 50 Hz.The signal intensity distribution is differentiated from that of ITSC faults.The ratio of the signal intensity difference energy(SIDER)are 7.13%and 13.96%for the no-load ITSC condition,and 6.66%and 13.44%for the load ITSC condition,much greater than zero,which can effectively identify the ITSC faults.The experiments on salient synchronous generator show that:the TFMCC of static eccentric compound ITSC 2.5%,5%,and 7.5%under no-load conditions,the signal intensity at the intersection of time and characteristic frequency has changed significantly,and the signal intensity differences at 25 Hz before and after the fault are 13.05,21.06,and 29.86 dB,respectively.The SIDER are 4.16%,5.23%,and 11.11%,respectively.Meanwhile,the static eccentricity compound ITSC of 1%,2.5%,and 4.9%under load conditions,and the signal intensity differences at 25 Hz before and after the fault are 29.64,38.56,and 71.81 dB,respectively.The SIDER are 2.28%,3.13%,and 15.68%,respectively,which shows that the method can effectively detect weak ITSC faults and locate the time of fault occurrence.The experimental results demonstrate that the method eliminates static eccentricity and armature response disturbances,and visualizes the operating conditions of the unit with a three-dimensional map that includes operating time,characteristic frequency,and signal intensity.At the same time,to effectively identify weak ITSC faults,this study also calculates that the SIDER of the time-frequency matrix can further quantify the magnitude of the fault and prevent false alarms,which can provide guidance for field operation and inspection personnel to carry out condition maintenance work.
作者
齐鹏
李永刚
马明晗
武玉才
纪璇
Qi Peng;Li Yonggang;Ma Minghan;Wu Yucai;Ji Xuan(School of Electrical and Electronic Engineering North China Electric Power University,Baoding 071003 China)
出处
《电工技术学报》
EI
CSCD
北大核心
2023年第22期6104-6120,共17页
Transactions of China Electrotechnical Society
基金
国家自然科学基金(52277048)
河北省自然科学基金(E2020502064)资助项目。
关键词
抽水蓄能机组
励磁绕组
匝间短路
环流时频图谱
Pumped storage units
excitation winding
inter-turn short circuit
time-frequency map of circulating current
作者简介
齐鹏,男,1991年生,博士研究生,研究方向为旋转电力设备运行特性分析及故障诊断。E-mail:qipeng91@foxmail.com;通信作者:武玉才,男,1982年生,副教授,硕士生导师,研究方向为旋转电力设备运行特性分析及故障诊断、高速磁悬浮及驱动系统设计。E-mail:wuyucaincepu@163.com。
