直流输电单极大地运行引起变压器偏磁的研究
摘要
直流输电系统在我国得到广泛的应用,当它处于单极大地运行时,部分地中直流电流通过变压器中性点,经由交流输电线路从另一端的变压器中性点进入变压器,并形成回路,从而影响电力系统的正常工作。本文对直流偏磁的机理进行详细的阐述,由于变压器铁心类型不同,其影响也不同。
本文将经验模态分解(Empirical Mode Decomposition,EMD)和Hilbert变换应用在直流偏磁的仿真研究中。利用MATLAB建立直流偏磁仿真模型,仿真结果表明随着直流电压的增加,励磁电流畸变程度增加。利用EMD提取畸变后励磁电流的IMF1分量,再对IMF1作Hilbert变换求瞬时频率和幅值。该方法能够准确检测出励磁电流畸变的时间、频率、幅值。将EMD理论应用在直流偏磁研究领域中,为此理论在变压器直流偏磁领域的深入研究提供了依据。
以三相电力变压器为仿真对象,根据实体的具体参数,利用有限元原理,在ANSYS环境下进行三维实体建模。当电力变压器空载工作时,中性点注入直流电压,查看在铁心中所产生的漏磁通分布及漏磁磁密数值范围。ANSYS环境下的三维直流偏磁模型比二维模型能更直观准确的反应漏磁场的分布。
讨论了在系统中抑制直流偏磁的措施和变压器铁心设计对直流偏磁的影响,介绍变压器中性点注入反向电流法、变压器中性点串联电阻法、变压器中性点串联电容法、交流线路串联电容器法,并对其优缺点做了比较详细的说明。
DC transmission system has been widely applied in our country,during mono-polar operation of DC system with ground return, part of the DC in the land through transformer neutral point, DC through the other side of the transformer into the transformer neutral point by AC system, and constitute circuit. The theoretic baffling problems concerned have been researched. It affects normal running of power system. Because the transformer core is different, the effects are also different.
EMD and Hilbert transform are applied in simulation study under DC bias. By use of MATLAB, simulation model of DC bias is established. The results show that DC voltage increases, the distortion of exciting current increases. By EMD method, extracts the IMF1 of the signals. Then the Hilbert transform is applied in IMF1 to obtain the instantaneous frequency and amplitude. With this method, the time,frequency and amplitude information of the exciting current distortion can be accurately detected. EMD is first applied in DC bias in this paper, it provides proof for further study on transformer under DC bias based on the theory.
Three-phase power transformer is simulated, according to practical parameters of entity, finite element theory, building the 3D solid modeling by ANSYS. When the power transformer run with no-loading, the DC voltage will injected into the neutral point, to see the distribution of leakage magnetic flux of iron core and flux density range of values. 3D model of DC bias is better than 2D model by ANSYS, it can more intuitively and accurately reflect to distribution of leakage magnetic field.
Discussing measures of restraining DC bias in system and designing of transformer core about the DC bias. Introduced the transformer neutral point reverse current method, transformer neutral point series resistance method,transformer neutral point series capacitor method, the AC lines series capacitor method, and do a more detailed explanation for their advantages and disadvantages.
本文将经验模态分解(Empirical Mode Decomposition,EMD)和Hilbert变换应用在直流偏磁的仿真研究中。利用MATLAB建立直流偏磁仿真模型,仿真结果表明随着直流电压的增加,励磁电流畸变程度增加。利用EMD提取畸变后励磁电流的IMF1分量,再对IMF1作Hilbert变换求瞬时频率和幅值。该方法能够准确检测出励磁电流畸变的时间、频率、幅值。将EMD理论应用在直流偏磁研究领域中,为此理论在变压器直流偏磁领域的深入研究提供了依据。
以三相电力变压器为仿真对象,根据实体的具体参数,利用有限元原理,在ANSYS环境下进行三维实体建模。当电力变压器空载工作时,中性点注入直流电压,查看在铁心中所产生的漏磁通分布及漏磁磁密数值范围。ANSYS环境下的三维直流偏磁模型比二维模型能更直观准确的反应漏磁场的分布。
讨论了在系统中抑制直流偏磁的措施和变压器铁心设计对直流偏磁的影响,介绍变压器中性点注入反向电流法、变压器中性点串联电阻法、变压器中性点串联电容法、交流线路串联电容器法,并对其优缺点做了比较详细的说明。
DC transmission system has been widely applied in our country,during mono-polar operation of DC system with ground return, part of the DC in the land through transformer neutral point, DC through the other side of the transformer into the transformer neutral point by AC system, and constitute circuit. The theoretic baffling problems concerned have been researched. It affects normal running of power system. Because the transformer core is different, the effects are also different.
EMD and Hilbert transform are applied in simulation study under DC bias. By use of MATLAB, simulation model of DC bias is established. The results show that DC voltage increases, the distortion of exciting current increases. By EMD method, extracts the IMF1 of the signals. Then the Hilbert transform is applied in IMF1 to obtain the instantaneous frequency and amplitude. With this method, the time,frequency and amplitude information of the exciting current distortion can be accurately detected. EMD is first applied in DC bias in this paper, it provides proof for further study on transformer under DC bias based on the theory.
Three-phase power transformer is simulated, according to practical parameters of entity, finite element theory, building the 3D solid modeling by ANSYS. When the power transformer run with no-loading, the DC voltage will injected into the neutral point, to see the distribution of leakage magnetic flux of iron core and flux density range of values. 3D model of DC bias is better than 2D model by ANSYS, it can more intuitively and accurately reflect to distribution of leakage magnetic field.
Discussing measures of restraining DC bias in system and designing of transformer core about the DC bias. Introduced the transformer neutral point reverse current method, transformer neutral point series resistance method,transformer neutral point series capacitor method, the AC lines series capacitor method, and do a more detailed explanation for their advantages and disadvantages.
引文
[1]毛晓明,吴小晨.南方交直流并联电网运行问题分析.电网技术,2004,Vol.28(2):6～13
[2]梅桂华,徐柏榆等.直流输电对交流系统变压器的影响.广东电力,2006,Vol.19(1):1～7
[3]刘海波.变压器运行噪音问题的探讨.安徽电力,2005,Vol.22(3):23～26
[4] A.P.Sakis Meliopoulos, George Christoforidis.Effects of DC Ground Electrode on Converter Transformers.IEEE Transactions on Power Delivery, 1994, Vol. 9(1):995～1002
[5]姜涛,马国庆,关高.直流输电系统接地极运行对变压器的影响.吉林电力,2007,Vol.35(5):23～25
[6]钟连宏,陆培均等.直流接地极电流对中性点直接接地变压器影响.高电压技术,2003,Vol.29(8):12～14
[7]李晓萍,文习山,樊亚东等.直流入侵三相三柱变压器励磁电流及谐波计算.高电压技术,2006,Vol.32(5):69～72
[8] Yu Cui, Sami G. Abdulsalam,Shiuming Chen,Wilsun Xu.A Sequential Phase Energization Technique for Transformer Inrush Current Reduction—Part I: Simulation and Experimental Results. IEEE Trans. Power Del., 2005, Vol. 20(2):943～949
[9] D.H.Boteler.“Geomagnetically Induced Currents:Present Knowledge and Future Research”, IEEE Trans. on Power Delivery, 1994, Vol.4 (1):50～58
[10] G. B. Kumbhar and S. V. Kulkarni.Analysis of Short-Circuit Performance of Split-Winding Transformer Using Coupled Field-Circuit Approach.IEEE Trans. Power Del., 2007,Vol.8(6):936～943
[11] A.P.Sakis Meliopoulos, George Christoforidis.Effects of DC Ground Electrode on Converter Transformers.IEEE Transactions on Power Delivery,1994, Vol.9(1):995～1002
[12]刘振亚.特高压电网.北京:中国经济出版社,2005
[13] Brigham,E.0.The fast Fouriertransform. NJ:Prentiee一Hall.1974. Drazin,P.GNonlinear systems.Cambridge University Press.1992,Vol.8(5):560～564
[14] Wilsun Xu, Sami G. Abdulsalam, Yu Cui, and Xian Liu, A Sequential Phase Energization Technique for Transformer Inrush Current Reduction—Part II: Theoretical Analysis and Design Guide. IEEE Trans. Power Del., 2005, Vol.20(2):950～957
[15]王世山,李彦明.电力变压器绕组电动力的分析计算.高电压技术,2002,Vol.38(4):22～25
[16]姚缨英.大型电力变压器直流偏磁现象的研究.沈阳工业大学[博士论文],2000
[17] Sami G. Abdulsalam, Wilsun Xu.A Sequential Phase Energization Method for Transformer Inrush Current Reduction—Transient Performance and Practical Considerations. IEEE Trans. Power Del., 2007,Vol. 22(1):208～216
[18]郭满生,程志光,张俊杰,刘兰荣.直流偏磁条件下单相三柱电力变压器三维磁场分析.变压器,2007,Vol.44(4):31～35
[19]胡毅,李景禄.直流接地极电流对中性点接地变压器的影响.变压器,1998,Vol.36(1):15~20
[20]蒯狄正,万达,邹云.直流输电地中电流对江苏电网设备影响的分析与处理.电力系统自动化,2005,Vol.29(2):81~82
[21]蒯狄正,万达,邹云.直流偏磁对变压器的影响.中国电力,2004,Vol.37(8):41~43
[22]徐晓刚,徐冠雷,王孝通等.经验模式分解(EMD)及其应用.电子学报,2009,Vol.37(7):581~585
[23]罗卫华,孙云莲.基于EMD方法的电力载波通信中的信号检测.继电器,2006,34(21):Vol.58~62
[24]刘慧婷.EMD方法的研究与应用.安徽大学,2004
[25]刘曲,郑健超,潘文等.变压器铁心承受直流能力的仿真和分析.变压器,2006,Vol.43(9):5~10
[26]朱艺颖,蒋卫平,曾昭华.抑制变压器中性点直流电流的措施研究.中国电机工程学报,2005,Vol.25(13):1~7
[27]龚曙光.ANSYS基础应用及范例解析.机械工业出版社,2003
[28]王世山,王德林,李彦明.大型有限元软件ANSYS在电磁领域的应用.高压电器,2002,Vo1.38(3):27~30
[29]文舸一.计算电子学的进展与展望.电子学报,1995,Vol.23(l0):62~68
[30]蒯狄正,刘成民,万达.直流偏磁对变压器影响的研究.江苏电机工程2004,Vo1.23(3):1~5
[31]唐兴伦,范群波,张朝晖,李春阳.ANSYS工程应用教程-热与电磁学篇.中国铁道出版社,2003
[32] C.Peng.“In-situ 3D concept design with a virtual city”, Design Studies, 2006,Vol.27(4):439~455
[33] T.Bonomi.Database development and 3D modeling of textural variations in heterogeneous, unconsolidated aquifer media: Application to the Milan plain. Computers &Geosciences 2007,Vol.35(3):134~145
[34]李泉凤.电磁场数值计算与电磁铁设计.清华大学出版社,2002
[35]金建铭,王建国译.电磁场有限元方法.西安电子科技大学出版社,2001
[36]朱艺颖,蒋卫平,曾少华,印永华.抑制变压器中性点直流电流的措施研究.中国电机工程学报,2005,Vol.25(13):1~7
[37]尚春.HVDC地中电流对交流变压器影响的抑制措施.高电压技术,2004,Vol.30(11):52~54
[2]梅桂华,徐柏榆等.直流输电对交流系统变压器的影响.广东电力,2006,Vol.19(1):1～7
[3]刘海波.变压器运行噪音问题的探讨.安徽电力,2005,Vol.22(3):23～26
[4] A.P.Sakis Meliopoulos, George Christoforidis.Effects of DC Ground Electrode on Converter Transformers.IEEE Transactions on Power Delivery, 1994, Vol. 9(1):995～1002
[5]姜涛,马国庆,关高.直流输电系统接地极运行对变压器的影响.吉林电力,2007,Vol.35(5):23～25
[6]钟连宏,陆培均等.直流接地极电流对中性点直接接地变压器影响.高电压技术,2003,Vol.29(8):12～14
[7]李晓萍,文习山,樊亚东等.直流入侵三相三柱变压器励磁电流及谐波计算.高电压技术,2006,Vol.32(5):69～72
[8] Yu Cui, Sami G. Abdulsalam,Shiuming Chen,Wilsun Xu.A Sequential Phase Energization Technique for Transformer Inrush Current Reduction—Part I: Simulation and Experimental Results. IEEE Trans. Power Del., 2005, Vol. 20(2):943～949
[9] D.H.Boteler.“Geomagnetically Induced Currents:Present Knowledge and Future Research”, IEEE Trans. on Power Delivery, 1994, Vol.4 (1):50～58
[10] G. B. Kumbhar and S. V. Kulkarni.Analysis of Short-Circuit Performance of Split-Winding Transformer Using Coupled Field-Circuit Approach.IEEE Trans. Power Del., 2007,Vol.8(6):936～943
[11] A.P.Sakis Meliopoulos, George Christoforidis.Effects of DC Ground Electrode on Converter Transformers.IEEE Transactions on Power Delivery,1994, Vol.9(1):995～1002
[12]刘振亚.特高压电网.北京:中国经济出版社,2005
[13] Brigham,E.0.The fast Fouriertransform. NJ:Prentiee一Hall.1974. Drazin,P.GNonlinear systems.Cambridge University Press.1992,Vol.8(5):560～564
[14] Wilsun Xu, Sami G. Abdulsalam, Yu Cui, and Xian Liu, A Sequential Phase Energization Technique for Transformer Inrush Current Reduction—Part II: Theoretical Analysis and Design Guide. IEEE Trans. Power Del., 2005, Vol.20(2):950～957
[15]王世山,李彦明.电力变压器绕组电动力的分析计算.高电压技术,2002,Vol.38(4):22～25
[16]姚缨英.大型电力变压器直流偏磁现象的研究.沈阳工业大学[博士论文],2000
[17] Sami G. Abdulsalam, Wilsun Xu.A Sequential Phase Energization Method for Transformer Inrush Current Reduction—Transient Performance and Practical Considerations. IEEE Trans. Power Del., 2007,Vol. 22(1):208～216
[18]郭满生,程志光,张俊杰,刘兰荣.直流偏磁条件下单相三柱电力变压器三维磁场分析.变压器,2007,Vol.44(4):31～35
[19]胡毅,李景禄.直流接地极电流对中性点接地变压器的影响.变压器,1998,Vol.36(1):15~20
[20]蒯狄正,万达,邹云.直流输电地中电流对江苏电网设备影响的分析与处理.电力系统自动化,2005,Vol.29(2):81~82
[21]蒯狄正,万达,邹云.直流偏磁对变压器的影响.中国电力,2004,Vol.37(8):41~43
[22]徐晓刚,徐冠雷,王孝通等.经验模式分解(EMD)及其应用.电子学报,2009,Vol.37(7):581~585
[23]罗卫华,孙云莲.基于EMD方法的电力载波通信中的信号检测.继电器,2006,34(21):Vol.58~62
[24]刘慧婷.EMD方法的研究与应用.安徽大学,2004
[25]刘曲,郑健超,潘文等.变压器铁心承受直流能力的仿真和分析.变压器,2006,Vol.43(9):5~10
[26]朱艺颖,蒋卫平,曾昭华.抑制变压器中性点直流电流的措施研究.中国电机工程学报,2005,Vol.25(13):1~7
[27]龚曙光.ANSYS基础应用及范例解析.机械工业出版社,2003
[28]王世山,王德林,李彦明.大型有限元软件ANSYS在电磁领域的应用.高压电器,2002,Vo1.38(3):27~30
[29]文舸一.计算电子学的进展与展望.电子学报,1995,Vol.23(l0):62~68
[30]蒯狄正,刘成民,万达.直流偏磁对变压器影响的研究.江苏电机工程2004,Vo1.23(3):1~5
[31]唐兴伦,范群波,张朝晖,李春阳.ANSYS工程应用教程-热与电磁学篇.中国铁道出版社,2003
[32] C.Peng.“In-situ 3D concept design with a virtual city”, Design Studies, 2006,Vol.27(4):439~455
[33] T.Bonomi.Database development and 3D modeling of textural variations in heterogeneous, unconsolidated aquifer media: Application to the Milan plain. Computers &Geosciences 2007,Vol.35(3):134~145
[34]李泉凤.电磁场数值计算与电磁铁设计.清华大学出版社,2002
[35]金建铭,王建国译.电磁场有限元方法.西安电子科技大学出版社,2001
[36]朱艺颖,蒋卫平,曾少华,印永华.抑制变压器中性点直流电流的措施研究.中国电机工程学报,2005,Vol.25(13):1~7
[37]尚春.HVDC地中电流对交流变压器影响的抑制措施.高电压技术,2004,Vol.30(11):52~54