对公共走廊中管道交流干扰缓解措施进行了基于粒子群算法的优化研究.建立了包含固态去耦合器排流装置和绝缘法兰等效模型的管道分布参数电路.分析了土壤电阻率均匀性、接地极屏蔽效应和接地电阻及其他地理限制因素对优化管道防护措施的影响,并在考虑多种因素下研究了多种防护措施的组合优化.比较研究了基于粒子群算法和常用的试错法对管道防护优化的效果.以乌兰公共走廊为案例,采用粒子群优化了正常运行时的交流干扰缓解措施.研究可为工程实践提供技术支持.

对交流输电线路对管道的暂态影响进行归纳,分为线路分合闸和故障态,前者不改变线路电路结构,后者根据电路结构的不同包括线路相线接地、断线,雷击杆塔未反击及发生反击等情况.该文理论分析暂态时输电线路对地下油气管道的电感性和电导性耦合,建立不同暂态下的线路-管道等效电路.进而实例研究暂态下海西—塔拉750kV交流输电线路乌兰段对邻近埋地天然气管道的电磁影响.线路操作时对管道的电磁影响小;线路单相接地、断线接地时,管地电位最大值分别为4.3kV和12.9kV;杆塔遭受雷击和反击时管地电位峰值分别可达18.4kV和37.2kV.反击时故障相电流产生的电感性耦合部分抵消了雷电流对管道的电导性影响.对管道采用固态去耦合器的防护措施,使瞬态电磁影响降低并抑制了其传播.研究结果可为交流输电线路和埋地金属管道共用走廊的设计提供技术参考和支持.

用易于理解的、微分形式的麦克斯韦方程组推导源自交流输电线路的管道感应电动势,根据传输线理论建立管道等效电路,进而理论分析交流输电线路稳态运行时对邻近地下管道的电磁耦合.提出一种可校正至同一时刻的管地电位分布的测量方法,并应用研究青海750kV等多电压等级的交流线路对邻近埋地天然气管道电磁影响的两个案例.海西—塔拉线路乌兰段公共走廊管道在750kV线路三相7％不平衡运行且管道未予保护时管地电位可达140.7V,正常运行时交流电流密度达到265.1A/m2;该走廊和西宁—玛尔挡公共走廊现场实测的管地电位均与对应运行条件下的计算结果相吻合,且直观地显示了管地电位含有值得研究的谐波成分.对两条走廊的管道新增防护措施,可使管地电位和交流电流密度大幅降低并达到缓解效果.本研究结果可为输电线路和埋地管道共用走廊的设计提供技术参考和支持.

研究冷轧硅钢片铁心磁性能和油纸绝缘介电性能对绕组频率响应的温度效应.推导稀疏线圈在有铁心和空心时的阻抗差异与铁心复磁导率,以及绝缘材料的阻抗与其复介电常数的频率依赖关系.在频率范围从1kHz到1MHz对铁心复磁导率、油和纸绝缘复介电常数和模型变压器两种绕组的频率响应进行从110℃自然降温到30℃的试验研究.获得铁心复磁导率、油和纸绝缘材料复介电常数随温度变化的规律,探讨了纸占比对油纸复合绝缘介电特性的影响,讨论铁心和油纸绝缘单独作用时绕组频率响应特征的变化趋势.进而用变压器这2种材料温度特性结合绕组等效电路解释了模型变压器层式绕组和饼式绕组的频率响应随温度变化的特征,认为绕组等效(合成)电感与等效电容的乘积变化最终决定了(反)谐振频率移动方向.为了正确地解释变压器绕组频率响应,应密切关注绕组变形试验时的温度.

架空导线作为输送电力的载体,其交流电阻对导线输送容量及线路损耗有直接影响。文中对巴雷特(Barrett)提出的关于导线交流电阻计算的等效电路模型做了改进并称之为磁特性分析法,计及复合磁导率随温度的变化和线芯导电性,考虑不同层铝绞线之间的温差,以及采用与磁通量计算区域边界吻合的圆弧形电流微元。分别以该法、摩根法(Morgan)和日本JCS 0374算法对一种铝包钢芯铝绞线计算了交直流电阻比,结果显示磁特性分析法计算值相对另外两种方法偏小,理论分析认为该法计算结果更为接近实际。

To locate partial discharge (PD) in power transformer, a combined array sensor is manufactured which consists of a cross-shaped ultrasonic array with 25 elements and an ultra-high frequency (UHF) array with 2*2 elements. Algorithms for PD location are studied based on the sensor arrangement, and a total of 193 ultrasonic and 13 UHF virtual elements are achieved via virtual expansion. At first, two-sided correlation transformation based on the UHF virtual expanded array is employed to pre-estimate the PD’s direction, and then rotated signal sub-space based on the ultrasonic array is used to direct accurately. To enhance the accuracy and success rate of an array, ray tracing technique which consists of geometrical optics and uniform geometric theory of diffraction is studied to backtrace the wave emitted by PD, considering the UHF signal as an example. The PD location experiments in a transformer model indicate that the location algorithms based on the proposed combined array sensor adapt the PD’s broadband signal well, and ray tracing of the electromagnetic wave emitted by PD makes the location much accurate and successful than that of a single array. The PD location based the proposed combined array takes the advantages of the high sensitivity of UHF array and the high accuracy of the ultrasonic array.

研究了一种利用传递函数特征的主成分和神经网络来智能识别变压器绕组变形故障的方法.针对某10 kV变压器的被试绕组设置了不同的、成体系的变形类型、位置和程度的模拟故障,并用M序列法测量获得对应的传递函数.以传递函数的零、极点作为状态特征量,为了准确快速地判断绕组状态,用主成分分析法对零、极点进行K-L变换从而获取其主成分.进而利用已经交叉验证的方法训练与通过训练并测试过的BP神经网络对绕组变形信息进行识别,结果表明该方法同时对变形类型、位置和程度具有较高的识别和诊断能力.该研究虽是在一个变压器上进行的,但它为绕组状态的智能识别提供了思路和途径.

为了对变压器中的局部放电进行精确定向,研究了一种基于传统旋转子空间(rotatedsub-spacetransformation,RSS)算法和高阶累积量技术的RSS改进算法。首先对13阵元L型超声阵列和25阵元十字型超声阵列虚拟扩展使阵元分别达到97个和193个;然后基于两种阵列及其扩展,用仿真和局部放电定向试验对比了RSS算法与其改进算法对单个和多个局部放电源的定向性能。研究结果表明:RSS改进算法使少阵元阵列也可以达到多阵元阵列的定向效果,增大了阵列孔径,减少了后续硬件电路并提高指向性能;能够良好地抑制噪声;对宽带信号仍有很好的定向性能且定向误差在3°以下。对RSS改进算法的研究为超声阵列技术应用于电力变压器局部放电定位奠定了基础。

研制了将25阵元十字型超声阵列和2×2阵元特高频阵列共同构成复合阵列传感器。研究了适用于复合阵列传感器的定位算法。将特高频阵列虚拟扩展为13阵元,超声阵列虚拟扩展为193阵元。利用扩展的特高频阵列由双边相关变换算法来预估局部放电源的方位,根据预估结果再对扩展的超声阵列使用旋转信号子空间算法进行精确定向。为了提高单一阵列在局部放电定位中定向成功率和精度,以特高频信号为例,利用基于几何光学与一致性几何绕射理论的射线追迹法研究了对局部放电辐射电磁波轨迹的反演。在变压器模型中的局部放电定位试验表明,基于复合阵列传感器的定位算法对局部放电产生的宽带信号有良好的适应性,以及对局部放电辐射电磁波的追迹反演使定位精确度与成功率均远大于单一阵列的结果,发挥了特高频阵列灵敏度高而超声阵列定向精确度高的优点。

为了有效地检测电力变压器绕组变形,及时发现变压器的潜在故障,结合频率响应法的基本原理,提出了基于周期性宽频带M序列激励的变压器绕组变形故障检测方法(M序列激励法).在介绍M序列信号的特性和产生方法后,给出了M序列级数、位持续时间和采样频率的选取原则.为了实施M序列激励法,研制了综合该法和扫频法的绕组变形检测装置,并通过实验室模拟绕组不同位置、不同程度匝间短路故障进行测试.结果表明:M序列激励法具有扫频法相同的检测精度,能够快速、准确地获得绕组的频响曲线.现场应用表明该方法具有良好的测量稳定性,能有效检测变压器绕组变形.

In this paper, an intelligent identification method for winding deformation fault is proposed. The proposed method is composed of principal components of transfer function characteristics and an artificial neural network (ANN). A sequence of simulative deformation faults with different types, locations and extents are set on the winding of a 10kV transformer. The corresponding status transfer function is acquired with a winding deformation test method excited by M-Sequence. Zeros, poles and the variations of the transfer function are considered to be the features of the winding mechanical status. The principal components of feature are extracted and then used as input to a back-propagation ANN for fault recognition. The winding deformation faults are recognized using the ANN that has been trained and tested using the cross validation method. The results show that the classification method has the ability to simultaneously recognize the deformation faults with different types, locations and extents with high accuracy and is suitable for winding deformation diagnosis. The study presents an idea and a path to identify winding mechanical status intelligently though it conducts on a transformer.

Besides the conductor's structure, AC resistance is also affected by external environmental factors.In order to study the in-fluence of all these factors, a test method to measure the AC impedance characteristics of a conductor is studied and the experiment platform is set up in this paper.AC impedance is designed to be measured by the outside ampere method in this experiment system, the current waveform is measured and restored by a hollow Rogowski coil and a followed integrator.A loop voltage equation is established by the time signals of the voltage drop and current of the conductor under test.The AC resistance of the conductor is identified with the Least Mean Square ( LMS) estimation algorithm, and AC/DC resistance ratio is obtained consequently.The results of experimental study on six kinds of conductor show that the developed test platform is suitable for measuring AC resistance of conductors, the LMS estimation algorithm can identify the AC resistance effectively.The method of reducing external self-induction of a conductor in a loop to improve the accuracy of measuring is also discussed.

With the diversification of the demand for new construction and reconstruction of transmission lines, the capacity increasing conductor will be gradually applied to AC/ DC transmission lines of various voltage levels. In existing transmission line design, the sag of transmission line are evaluated by empirical formula, which is verified merely in a 60 meters small span test in laboratory, and is quite different from the actual project. To understand the temperature rise and sag characteristics of typical conductors and provide basis for the selection of transmission line conductor, the first 200 m large span transmission line on actual strain tower for full scale test is built in Kunming UHV engineering technology lab to study on the temperature rise and sag characteristics of 4 kinds of conductors, including 1 kind of ordinary aluminum clad steel conductor and 3 kinds of typical augmented capacity conductor: carbon-fiber aluminum conductor composite core (ACCC), aluminum clad invar core aluminum alloy wire, and aluminum clad steel core aluminum alloy wire. The results show that ACCC and aluminum clad invar core aluminum alloy wire have better arc sag characteristics, and there are obvious temperature transfer points. The temperature transfer point of ACCC is about 75°C, and the transfer point of aluminum clad invar core aluminum alloy wire is about 105°C.

In order to judge the internal insulation status of cable accessories in time and accurately,to avoid the cable breakdown and cause a major accident,this paper studies the partial discharge of XLPE power cables.The discharge characteristics of three kinds of XLPE power cables are simulated in the laboratory environment.Three kinds of defective partial discharge characteristics of XLPE power cables are studied by ultrasonic inspection system.The ultrasonic signals of different defects are analyzed.The characteristics of the time domain and the phase spectrum of the signal are studied.The relationship between the voltage and the maximum discharge amplitude,the average discharge amplitude and the number of discharges is studied,and the typical discharge spectrum is drawn.The same defect type is stable and reproducible under the same conditions.The discharge process of different defect types is different,and the partial discharge spectrum,single pulse waveform and PRPD spectrum are obvious.It is of great significance to prevent the occurrence of cable accidents and to ensure the safe and stable operation of power system.

A test method to detect winding deformation by using pseudorandom binary M-Sequence excitation signals is proposed. This broadband excitation signal and the corresponding response from the winding are combined to obtain the analytic expression of the winding's transfer function by using a Recursive Least Square method. The coefficients, poles, and zeros of the transfer function can be used to describe the winding status, and any mechanical changes in the winding over time can be therefore detected. The steps and algorithms involved in using the M-Sequence method are presented, and a comparative simulation between the M-Sequence method and Frequency Response Analysis (FRA) is carried out using an equivalent circuit for the winding. Results of the simulation confirm that the response sensitivity of the M-Sequence method is as good as FRA in a common frequency band, and is actually more sensitive for slight winding deformations of series capacitance. The correlation factor of the transfer function coefficients, used as example, can also diagnose slight deformation. Additionally, significant differences exist in the map of the poles and/or zeros before and after deformation. The study confirms the feasibility of using the M-Sequence method for detection of winding deformation in transformers. Transfer function can have a wider application than frequency response curves, then analysis and judgment based on the transfer function may offer more analysis tools. The theory and simulation study of the new method provide supports for subsequent development of its corresponding detecting system as well as experimental research.

In order to implement the test method to detect winding deformation excited by pseudorandom binary M-Sequences (The M-Sequence method), a detecting instrument for winding deformation synthetically based on the M-Sequence method and Frequency Response Analysis (FRA) is developed. Three kinds of the artificial failures aimed to simulate winding deformation were set in a pie-type winding. Comparative experiments between the M-Sequence method and FRA were carried out, and the results show that frequency response and statistical characteristics of the M-Sequence method are consistent with those of FRA in the common frequency band, which proves that the two methods have the same accuracy in terms of frequency response. Transfer function coefficients obtained by the M-Sequence method as well as changes in the map of the poles and/or zeros can also indicate winding deformation. The experiments confirm that the M-Sequence method is a feasible approach for identifying winding deformation. Moreover, the on-site experiment shows that frequency responses obtained through the two methods are coincident in the common frequency band, while differences exist between the poles/zeros obtained by transfer function and peaks/troughs in the frequency response curve obtained by FRA. The presented study of this new method demonstrates that it has some advantages over FRA and lays the foundation for further practical applications.

为了更好地检测绕组变形,该文提出了一种用伪随机M序列激励的试验方法(M序列法)。采用伪随机M序列信号源来激励绕组,用递推最小二乘算法等直接从同时采集的激励和响应信号中获取绕组传递函数的解析表达式,利用传递函数的系数、所包含的零极点来描述绕组状态,进而通过分析他们的变化来判断绕组机械结构变化。研制了综合M序列法和频率响应分析法的绕组变形检测装置,并在饼式绕组上设置了三种模拟绕组变形的故障,对M序列法和频响法进行了试验对比。结果表明:二法在公共频段的频率响应吻合且统计特征相当,说明它们具有同等的精度;M序列法获得的传递函数系数和零极点变化能反映绕组变形,从零极点分布图中可直观地观察到一些故障类型和故障位置的信息,试验验证了M序列法用于辨识绕组变形的可行性。现场实验研究显示,二法在公共频段的频率响应吻合,传递函数的零极点和频响曲线的峰谷存在差异。该方法的研究验证了其可行性,相对频响法有优势,为进一步的实际应用奠定了基础。

In order to reduce the elements and the cost of follow-up circuit of a 16×16 ultrasonic array senor, two ultrasonic array sensors were designed, one was L-shaped with 13 elements and the other was cross-shaped with 25 elements. Based on these two ultrasonic array sensors, the directing performance of a two-sided correlation transformation (TCT) algorithm which can focus broadband signal, an array expanded algorithm based on fourth order cumulants, and a combination of these two algorithms were compared. Broadband focusing algorithm can well adapt to the broadband ultrasonic signal emitted by partial discharge (PD) source. After virtual expansion, the two ultrasonic arrays can achieve the effect of an array with 97 and 193 elements respectively. The adaptive capacity of broadband ultrasonic signal emitted by PD source, and the directing precision to PD were compared among the three algorithms. Directing simulation and experiment to single or multiple PD sources were carried out. The results show that with the combination of two algorithms, the directing precision is highest with error less than 2°, the peaks of spatial spectrum are most sharp, and the best broadband adaptive capacity and noise suppression ability can be achieved. This research should provide a foundation for application of array technology in power transformer.

An improved rotated sub-space (RSS) algorithm is proposed for the application of array technology in partial discharge (PD) location in transformer. The algorithm is based on classic RSS algorithm and high-order cumulants, and it is studied through numerical simulation and experimental tests. Based on an L-shaped and a cross-shaped array, the simulation of single and multiple PD source direction is carried out to compare the classic RSS algorithm with improved RSS algorithm. The results confirm the processing capacity in wideband focus, aperture expansion, enhance of directing, and noise suppression of improved RSS algorithm. Moreover, both algorithms are used for PD location experiments, showing that the error of improved RSS algorithm is ~3°. Improved RSS algorithm solves the problem of wideband focusing in PD location, enhances the performance of the array aperture and directing, achieves the effect of the array consists of much more elements with a virtual expansion, simplifying the follow-up circuit.

根据实际SF6电流互感器建立了介质损耗研究平台,采用了正接法、反接法对CT进行了介损测量.结果表明当采用底座悬空且二次侧与底座不连的正接法接线方式测量时,正常设备介损因数随电压的升高逐渐减小;而当采用底座与二次侧相连的正接法接线方式进行测量时,正常设备的介损因数随电压的升高稍有增大或不变;当采用反接法测量时,对于不同绝缘结构CT的介损因数基本不变.