【作者】 邵鹏飞；

【导师】 罗隆福；

【作者基本信息】 湖南大学 ， 电气工程， 2013， 博士

【摘要】 在电力工业迅速发展的今天，如何使资源与环境协调发展是我们面临的一个艰巨的挑战。对于我国的电力行业来说，既要为经济发展提供可靠的电力能源，还要保证输变电工程与环境的友好，这是电力行业非常关心的一项现实课题。直流输电对于实现全国范围内的资源优化配置和能源优化供给具有重要的意义，在我国的电力系统中已经得到了较为广泛的应用。但是，由于直流输电中电力电子器件的非线性行为的作用以及直流偏磁现象的发生，产生了大量的谐波电流和无功功率，这不仅仅污染了电能质量，对电网和系统带来不良影响，还将对换流站的各个器件，尤其是换流变压器造成危害。传统的直流输电滤波方案仅从电网的角度考虑，换流阀产生的特征次谐波仍然在变压器绕组中自由流通，此时绕组受到的电磁力将会增大，使得绕组电磁振动加剧。其危害表现为，一方面，绕组振动的加剧使得换流变压器的可听噪声严重超标；另一方面，还可能破坏变压器的绝缘结构，缩短换流变压器的使用寿命。本论文研究的感应滤波换流变压器是一种集成了感应滤波技术的新型换流变压器。旨在从谐波源处就近对谐波进行滤除，使得绝大部分的特征次谐波被屏蔽于阀侧绕组，网侧绕组中几乎没有谐波流过，从而达到抑制绕组电磁振动的作用。本论文主要目的就是对换流变压器的谐波电流与绕组电磁振动的关系进行研究，揭示在谐波条件下感应滤波换流变压器对绕组电磁振动的抑制作用。围绕上述问题，本文主要完成了如下研究工作：(1)研究了感应滤波换流变压器的接线方案和滤波机理，推导了感应滤波换流变压器的电压电流传递方程和绕组的匝比关系。详细推导了理想条件下，未投入和投入两种情况下感应滤波换流变压器的绕组电流计算方法，并通过计算电流波形与实测波形的对比验证了计算方法的正确性，计算电流和实测电流都显示感应滤波换流变压器对绕组谐波电流具有优良的抑制作用。同时这也为谐波条件下绕组电磁力的计算打下了基础；(2)通过对毕奥-沙瓦定律和拉格朗日定理的详细比较，确定了采用拉格朗日定理对感应滤波换流变压器进行绕组电磁力计算。利用拉格朗日定理和多绕组变压器理论，对谐波条件下感应滤波器的绕组电磁力进行了详尽的推导，得到了各个绕组在未投和投入感应滤波装置时的径向和轴向电磁力，计算结果表明投入感应滤波装置能够有效的减小原边绕组和公共绕组径向力的幅值；(3)根据直流输电系统研究平台中的单相感应滤波换流变压器，建立了变压器绕组和铁心的有限元模型，确定了模态分析的方法，并分析了对感应滤波换流变压器振动模态分析的基本思路。通过振型比对，确定了绕组的边界条件为自由边界，而铁心模态分析的边界条件为底部约束。模态计算结果表明，绕组的固有频率避开了特征次谐波的两倍频避免了共振的发生，并且网侧绕组是各个绕组中最易于振动的部分。为了避免铁心可能发生的共振，提出了加载预紧力的解决措施，并重新计算了铁心模态，验证了措施的可行性；(4)建立了谐波条件下绕组振动的有限元模型，其网格剖分采用了扫掠的方式，保证了绕组节点分布的径向和轴向的对称性，这与绕组的受力和振动的性质相对应。对于铁心对绕组振动的影响做了合理的简化，确定了有限元瞬态动力学计算的边界条件。针对绕组电磁力为不规则的波形，对电磁力激励的加载采取了将电磁力均分为多个相等的载荷步的离散化处理。经过有限元计算得到了在四种工况下绕组的振动特性，计算结果表明，感应滤波技术对各个绕组的振动有明显的抑制作用，其中5、7次感应滤波装置对绕组振动有较大的抑制作用；(5)研究了感应滤波换流变压器在直流偏磁下的谐波抑制机理，建立了基于matlab的感应滤波换流变压器直流偏磁实验仿真模型，得到了两种直流偏置引入方式下的变压器励磁电流和各个绕组电流，验证了感应滤波换流变压器能够阻止谐波电流扩散至原边绕组。对绕组和相应铁心的有限元模型加载直流偏磁下的电磁力激励，经有限元计算得到了各个绕组在两种直流侵入方式下的振动特性。对绕组的振动特性分析显示，在投入感应滤波装置前，绕组的振动在网侧引入直流偏置的方式下要更为剧烈，投入感应滤波装置后，两种直流偏置引入方式下的绕组振动显著降低且十分接近，表明感应滤波技术能有效的抑制直流偏磁下的绕组振动。本文通过系统地研究感应滤波换流变压器绕组在振动方面的特性，构建了一套比较完善的绕组振动研究体系。通过对绕组振动模态、谐波条件下的绕组振动以及直流偏磁下的绕组振动进行深入研究，揭示了感应滤波技术对绕组电磁振动的抑制作用，表明了感应滤波换流变压器具有良好的工程应用前景。更多还原

【Abstract】 In the period with booming Power Industries, to coordinated development ofresources and environment is a tough challenge we faced with. For China’s powerindustry, it not only needs to provide reliable electrical energy for economicdevelopment, but also to ensure that the power transmission project environment-friendly, which is a realistic subject power industry concerned about. DC transmissionis of great significance for achieving the optimal allocation of resources and energyoptimizing supply nationwide, and it has been widely used in China’s electricitysystem. However, due to the non-linear behavior of the power electronic devices of DCtransmission as well as the DC magnetic bias phenomenon occurred, resulting in alarge number of harmonic currents and reactive power, which not only pollutes thepower quality of the power grid，but also do harm to the respective devices of theconverter stations, especially converter transformer. The traditional filtering scheme ofDC power transmission only take power grid into consideration, the characteristicharmonic currents generated by commutating valve still free flow in the transformerwindings, then the electromagnetic forces of windings will be increased, which causeelectromagnetic vibration of the windings intensified. On the one hand, convertertransformer windings vibration makes the audible noise beyond the standards seriously;the other hand, it may damage the transformer insulation structure, shortening theservice life of the converter transformer.Inductive filtering converter transformer of this thesis is a new convertertransformer integrated inductive filtering technology. It can perform the harmonicsuppression nearby harmonic source, making the most of the characteristics harmonicshield in valve winding, and almost no harmonic currents flow through the primarywinding. By this way, the winding electromagnetic vibration can be suppressed. Basedon the inductive filtering converter transformer and its winding electromagneticvibration, the fundamental research and the related innovative achievement in thisthesis can be summarized as follows:(1) Inductive Filtering wiring scheme of converter transformer and its filteringmechanism are researched, derived voltage and current transfer equations of inductivefiltering converter transformer and its winding turns-ratio. In ideal conditions, current calculation method of inductive filtering converter transformer winding are derived, bycomparing with the measured waveform, the correctness of the calculation method isverified. Calculated current and measured current shows the inductive filters greatlysuppressed the windings harmonic currents of converter transformer, which also laidthe foundation for the winding electromagnetic forces calculation consideringharmonics currents;(2) By detailed comparing of Biot-Savart’s law and Lagrange’s theorem,Lagrange’s theorem is determined to calculate windings electromagnetic forces ofinductive filtering converter transformer. Based on Lagrange’s theorem and themulti-winding transformer theory, winding electromagnetic forces on the harmonicconditions in both radial and axial directions are computed. The calculation resultsshow that the inductive filters effectively reduced the amplitude of the radial forces ofthe primary winding and the common winding;(3) Based on the single-phase inductive filtering converter Transformers of DCtransmission system research platform, a finite element model of the transformerwindings and core are established. Modal analysis method and the basic ideas ofinductive filtering converter transformer vibration modal analysis are determined. Bychecking modes, determined the winding boundary condition is free boundary, and thecore boundary condition is bottom with constraints. Modal calculation results showthat the natural frequencies of the windings avoid the occurrence of resonance withtwice harmonic frequency, and the primary winding is the most easily vibrationportion of all windings. In order to avoid the resonance of the core, a measure that loadprestressing force on core is put forward. By recalculating the core vibration modal,the feasibility of the measure is verified;(4) The winding vibration finite element model under harmonic conditions isestablished. Sweep mesh is adopted to ensure the radial and axial symmetry ofwinding node distribution, which is consistent with force and vibration directions ofwindings. The effect of core vibration is reasonably simplified and the boundarycondition of the transient dynamics calculation is determined. As for irregularwaveform, the electromagnetic forces are divided into a large number of equal loadsteps. The finite element calculation results show the vibration characteristics in fourdifferent conditions, it reveals inductive filtering technology significantly suppressedthe vibration of windings, and5,7order inductive filters are more effectively inwinding vibration suppression than11,13order inductive filters;(5) The harmonic suppression mechanism of inductive filtering converter transformer under DC magnetic bias is researched, and the inductive filteringconverter transformer DC magnetic bias experimental matlab simulation model isestablished. Transformer exciting current and winding current are obtained in two DCbias introduced way that verified the inductive filtering converter transformer canprevent harmonic current spread to the primary winding. By the finite elementcalculating, the vibration characteristics of all windings are obtained in the two DCbias introduced way. Analysis of the winding vibration characteristics showed that,without inductive filters, the vibration of the windings are more severe when DC biasintroduced from primary winding; with inductive filters, the vibration of the windingsare significantly reduced in two DC bias introduced way, indicating that the inductivefiltering technique can effectively suppress windings vibration under DC magneticbias.This thesis makes a systematic study of the inductive filtering convertertransformer’s winding vibration characteristics, and a relatively complete theorysystem of winding vibration is founded. By in-depth studying of winding vibrationmodes, the windings vibration in harmonic conditions revealed the winding vibrationsuppression effect of the inductive filtering technique, which indicates that theinductive filtering converter transformer has a good engineering application prospect.更多还原