干式空心电抗器我物理场分析及应用研究

发布时间：2018-06-16 10:11

本文选题：干式空心电抗器 + 磁场屏蔽　；参考：《武汉大学》2014年博士论文

【摘要】：作为特高压交直流输电工程的主要感性元件之一,干式空心电抗器具有线性度高、结构简单、免维护等优点,因功能用途不同,在输电系统中起到无功补偿、限制短路电流、滤除高次谐波、减少直流系统谐波分量等作用。随着输电工程电压等级不断提升,电网规模日益扩大,数量庞大的干式空心电抗器投运到输电工程中。作为输电工程的强磁场源之一,干式空心电抗器漏磁严重,对周围电气设备运行有一定干扰,对职业人员、周边民众健康存在潜在危害。工程上,干式空心电抗器磁场屏蔽措施易于评估,而最优方案却难以获得。同轴多层包封结构,造成工程运维难以检测到电抗器包封热点温升变化情况,且缺少有效的在线监测设备,难以及时解决电抗器的长期持续过热运行,不仅会缩短电抗器工作寿命,甚至会引发起火烧毁等严重事故,对输电工程的安全运行造成极大危害。时变电流激励下的干式空心电抗器受迫振动,影响电抗器的机械性能,引起的疲劳损伤会造成潜在故障,电抗器向周围产生的结构辐射噪声也日益成为输变电工程中主要噪声源之一。基于上述干式空心电抗器暴露出的若干问题,本文在干式空心电抗器漏磁严重问题、温升特性、振动特性以及在线监测等方面开展主要研究工作： (1)干式空心电抗器磁场屏蔽优化研究。基于工频磁场屏蔽原理,建立了干式空心电抗器磁场屏蔽优化模型,提出微分进化算法结合棱边有限元的混合优化算法求解该优化问题,优化模型考虑电抗器中心距、屏蔽体结构参数等对目标函数的综合影响。对三相品字形排列电抗器组磁场进行屏蔽优化,优化结果表明：提高屏蔽板的架设高度和增大直径可有效降低最大磁感应强度,适当降低电抗器中心距可有效改善平均磁感应强度。该算法避免了人工单一因素搜索方法的局限性,为干式空心电抗器磁场屏蔽提供参考,优化模型及优化算法同样适用于其它高压设备电磁场优化研究。 (2)干式空心电抗器三维流固耦合温度场研究。基于计算流体力学和传热学理论,建立了干式空心电抗器流固耦合温度场数学模型,首次考虑了星型支架涡流损耗对包封端部温度的影响。应用结构化网格对三维模型进行剖分,采用有限容积法直接求解电抗器稳态流场与温度场,获得了电抗器温度场分布特性,总结了包封温度分布特性以及热点温升规律。包封轴向温度分布可以划分为三个温度梯度不同区域,热点区域主要集中在包封上端区域,星型支架涡流损耗对包封热点温度影响约为3K。研究了强制对流改善电抗器热点温升的效果,空气流速与热点温度存在非线性递减关系,且随着空气流速增大,强制对流散热效果将趋于饱和状态。文中计算模型及计算方法可为干式空心电抗器温升监测提供依据,同样可用于其它高压设备流固耦合温度场研究。 (3)干式空心电抗器温升试验测量与噪声试验测量。应用光纤测温法测量了自然对流条件下的干式空心电抗器温升,包封温度测量值与计算值相关系数为0.918,吻合度好,试验测量结果验证了温度场数值计算的准确性及有效性。对干式空心电抗器开展了噪声频谱试验测量,测量结果表明：在工频电流激励下,干式空心电抗器电磁振动产生的辐射噪声主要贡献量为100Hz声压。 (4)干式空心电抗器电磁振动数值计算,基于磁场与结构顺序耦合方式,采用有限元法对干式空心电抗器结构模态进行分析,获得电抗器的固有频率和模态振型,基于谐响应分析,将干式空心电抗器在工频电流激励下的电磁力映射到结构网格上,计算得到干式空心电抗器的振动频谱,计算结果表明：干式空心电抗器包封振动以径向振动为主,轴向振动较小。 (5)干式空心电抗器在线测温及温升故障预警系统设计。为了减少干式空心电抗器温升故障引起的运行事故,同时,将流固耦合温度场研究成果应用到实际工程中,设计了干式空心电抗器在线测温系统,分析了测温信号和布置方式,选择光纤光栅传感器作为测温元件。考虑了环境温度、相对湿度和日照强度中对电抗器热点温升的影响,提出微分进化算法结合支持向量机的电抗器温升回归模型,结合热点温升限值标准进行温升故障判断,可有效减少温升故障误判。该在线测温系统抗干扰能力强、预警准确性高,填补了干式空心电抗器实时监控和保护机制的空白。
[Abstract]:As one of the main inductive components of UHV AC and DC transmission project, dry air core reactor has the advantages of high linearity, simple structure and no maintenance. Because of different functional uses, it plays a reactive power compensation in the transmission system, limits the short circuit current, filters high harmonic and reduces the harmonic component of the DC system.
With the continuous upgrading of the voltage level of the transmission engineering and the increasing scale of the power grid, a large number of dry hollow reactor is transported to the transmission project. As one of the strong magnetic sources of the transmission engineering, the dry type air reactor has a serious leakage of magnetic flux, which has certain interference to the operation of the surrounding electrical equipment, and has a potential harm to the health of the workers and the people around them. In engineering, the magnetic shielding measures of the dry type air reactor are easy to be evaluated, but the optimal scheme is difficult to obtain. The coaxial multilayer encapsulation structure makes it difficult for engineering operation and maintenance to detect the temperature rise of the hot spot of the reactor envelope, and it is short of effective on-line monitoring equipment. It is difficult to solve the long-term and continuous overheating operation of the reactor, and it will not only shorten the long term overheating operation of the reactor, but not only shorten the long term overheating of the reactor. The working life of the reactor may even cause serious accidents such as fire and burning, which will cause great harm to the safe operation of the transmission project. The dry type reactor under the time-varying current is forced to vibrate and affects the mechanical performance of the reactor. The fatigue damage caused by the reactor will cause the potential failure, and the structure radiation noise generated around the reactor is also daily. Interest has become one of the main noise sources in the power transmission and transformation project.
Based on the problems exposed by the above dry air reactor, the main research work on the serious magnetic leakage problem, the temperature rise characteristic, the vibration characteristics and the on-line monitoring of the dry air core reactor is carried out in this paper.
(1) optimization of magnetic shielding of dry air reactor. Based on the principle of frequency magnetic field shielding, an optimization model of magnetic shielding for dry type hollow reactor is established. A hybrid optimization algorithm is proposed to solve the optimization problem with a hybrid optimization algorithm combined with edge finite element. The optimization model takes into account the center distance of the electric reactance device and the structure parameters of the shield. The optimization results show that increasing the erection height and increasing the diameter of the shielding plate can effectively reduce the maximum magnetic induction intensity, and reduce the center distance of the reactor effectively to improve the average magnetic induction intensity. This algorithm avoids the artificial single factor search method. The limitations provide reference for the shielding of dry air core reactors, and the optimization model and optimization algorithm are also applicable to other electromagnetic fields optimization of high voltage equipment.
(2) study on three-dimensional flow and solid coupling temperature field of dry type air reactor. Based on computational fluid mechanics and heat transfer theory, a mathematical model of fluid solid coupling temperature field in dry air reactor is established. The influence of the eddy current loss on the end temperature is considered for the first time. The three-dimensional model is dissecting with the structure grid and the finite volume is adopted. The product method is a direct solution to the steady-state flow field and temperature field of the reactor. The distribution characteristics of the reactor temperature field are obtained. The distribution characteristics of the enveloping temperature and the temperature rise law of the hot spot are summarized. The axial temperature distribution of the envelope can be divided into three different regions of temperature gradient. The hot spots are mainly concentrated in the upper end area, and the eddy current loss of the stellar support is sealed. The effect of the hot temperature is about 3K., and the effect of the forced convection to improve the temperature rise of the reactor is studied. There is a nonlinear decreasing relation between the air velocity and the hot spot temperature, and the effect of the forced convection heat dissipation will become saturated with the increase of the air velocity. The calculation model and the calculation method in this paper can provide the basis for the temperature rise monitoring of the dry type air reactor. It can also be applied to the study of fluid solid coupling temperature field in other high voltage equipment.
(3) the temperature rise test measurement and the noise test measurement of the dry type air reactor. The temperature rise of the dry type air reactor under natural convection is measured by the optical fiber temperature measurement. The correlation coefficient of the enveloping temperature measurement value and the calculated value is 0.918, the coincidence degree is good. The experimental measurement results verify the accuracy and effectiveness of the numerical calculation of the temperature field. The noise spectrum test is carried out in the electrocardiogram resistance device. The measurement results show that the main contribution of the radiation noise generated by the electromagnetic vibration of the dry type reactor is 100Hz sound pressure under the power frequency current excitation.
(4) the numerical calculation of the electromagnetic vibration of the dry type air reactor is based on the coupling of magnetic field and structure. The finite element method is used to analyze the structure mode of the dry type air reactor, and the natural frequency and modal shape of the reactor are obtained. Based on the harmonic response analysis, the electromagnetic force of the dry type air reactor is mapped to the structure under the power frequency current. On the grid, the vibration spectrum of the dry type air reactor is calculated. The calculation results show that the main vibration of the dry type air core reactor is radial vibration, and the axial vibration is smaller.
(5) design of the on-line temperature measurement and temperature rise early warning system for dry type air reactor. In order to reduce the operation accidents caused by the temperature rise failure of the dry type air reactor, at the same time, the research results of the fluid solid coupling temperature field are applied to the actual project. The on-line temperature measuring system of the dry type air reactor is designed, and the temperature measurement signal and the layout method are analyzed. The fiber Bragg grating sensor is used as the temperature measuring element. Considering the influence of ambient temperature, relative humidity and sunshine intensity on the temperature rise of the reactor hot spot, the differential evolution algorithm combined with the support vector machine's temperature rise regression model is put forward, and the temperature rise barrier is judged by the hot temperature rise limit standard, which can effectively reduce the error of temperature rise fault. The line temperature measurement system has strong anti-interference ability and high early warning accuracy, filling the blank of real-time monitoring and protection mechanism for dry type air core reactor.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM47

【参考文献】