When the cable hybrid transmission line fails,more complex traveling wave refraction and reflection will appear,which brings great difficulty to fault location.In order to solve such problems,according to the different structures and characteristics of cables and overhead lines,the distributed traveling wave detection devices are in-stalled on transmission lines to divide the lines into several sections.The correlation principle of Pearson's correlation coefficient is applied to determine the interval of fault occurrence.Through detailed formula derivation,the influence of the wave speed on the ranging accuracy is canceled,and the second singular value decomposition(SVD)compo-nent is used to demarcate the maximum value of the pulse mode of the singular point of the signal,and the fault lo-cation algorithm for hybrid lines without wave speed between sub-divisions is deduced.The results of PSCAD simu-lation and MATLAB data processing show that compared with the conventional single and double-terminal location method applied to the hybrid transmission line composed of cables,the location accuracy can be further improved.

To tackle the challenge of localization failure due to traveling wave dispersion during a mid-line fault in a long high-voltage cable, this study conducts an in-depth analysis of the refraction characteristics of the cumulative three-phase sheath currents at cross commutation points and direct grounding points, facilitated by detailed theoretical derivation. We introduce the novel concept of a 'first traveling wave attenuation index,' which quantifies the peak of the initial faulted traveling wave. We strategically place distributed traveling wave detection devices solely in the first direct grounding box of each cross-interconnected main section, effectively segmenting the line into five distinct zones. These zones are identified based on the unique transient polarities exhibited by the first traveling wave of fault current at each impedance mismatch point along the cable. To overcome the issue of weak traveling wave signals collected at the first end measurement point, we propose an innovative peak detection method for the first wave. This method harnesses the power of empirical wavelet transform (EWT) and multi-resolution singular value decomposition (MRSVD), providing a significant boost in ranging accuracy compared to traditional wavelet methods. Simulation results validate the efficacy of our proposed fault location method, which accurately pinpoints the fault section by contrasting the polarity of the first wave peak of the sheath current detected at each measurement point. Notably, our method ensures safety and convenience as the equipment does not require direct contact with high voltage.

针对现有小电流接地故障行波选线方法高度依赖行波初始波头的不足,通过分析三芯电缆故障行波折、反射过程,提出了基于行波电流波形综合相似度比较的小电流接地系统电缆故障选线方法.该方法首先利用S变换提取电缆故障产生的金属护层接地线行波电流时频信息,然后构造行波电流信号的时频能量矩阵和波形相似度矩阵,进而根据波形相似度矩阵计算每条线路和其他线路的行波波形综合相似度系数,最后通过比较波形综合相似度系数实现故障选线.仿真和实测数据分析表明,所提出的方法可以充分利用暂态行波故障信息,且不受系统中性点接地方式、故障位置、过渡电阻等因素影响,选线结果准确、可靠.

针对故障定位传统矩阵算法在含分布式电源配电网适用性变差,在未考虑实际馈线中含有不同类型终端及信息漏报情形下,需再次获取节点信息二次构造网络描述矩阵和难以处理T接线误判的问题,提出一种故障定位优化矩阵算法,该算法基于故障设备一定只含过流流入特性,建立新的设备故障判据,提出运用特殊量标记相关终端告警信息,通过类矩阵初等变换融合特殊量,并给出隔离方案的处理策略.算例分析表明,该算法简单、有效,可同时给出故障区域和控分方案,适应含DG的复杂配电网故障定位.

针对配电网故障定位困难问题,提出一种基于广域行波能量与时差的配电网故障定位新方法.首先分析了故障后行波能量的守恒和衰减原理,根据检测点获得的故障信息计算行波能量,直接确定故障区段;然后对故障区段两侧检测点进行访问,扩展为多级有效测距网络,提出三端测距法计算多级故障距离;对多个测距结果运用Grubbs检验法处理,确定故障点.理论分析与仿真结果表明,该算法具有准确性和可行性,不受波速度影响,鲁棒性强.

城市电缆网络产生故障时,故障线路的精确辨识及故障点的准确定位有利于快速恢复供电.针对城市电缆多埋于地下、结构复杂、分支多、传统定位算法较为繁琐等问题,在有效分析电缆线路结构与行波传播路径的基础上,提出了一种基于行波时差矩阵算法的多分支电缆线路故障定位方法.该方法首先划分线路的各个区段,然后根据线路网络拓扑结构与行波传播路径构建故障判定矩阵,最终依据故障判定矩阵与双端行波定位原理准确定位故障点.PSCAD仿真结果表明,该方法能快速精确地判定故障分支并定位故障点.

针对分布式电源配电网的故障信息误报导致故障定位容错率不高的问题,提出了一种基于改进的整数规划故障定位模型.在整数规划故障定位模型的基础上,采用层次分析法(AHP),以单电源辐射型配电网中各个自动化开关距离系统电源的相对距离作为参考依据确定权重值,通过不同权重值确定不同自动化开关评价函数的优先等级,进而得到了改进整数规划的故障定位模型.

为解决带T型分支的多段式架空线—电缆混合输电线路故障测距问题,提出了一种基于时间轴整定的T型混合线路故障测距方法.首先,根据三个假定的端点故障位置整定出以线路任意两端时间差为基准的三个时间轴,使得在线路任意一点发生故障时总能在其中两个时间轴中找到对应点;其次,以线路三端得到的三个时间差在对应时间轴中的位置作为故障区段判据,三个判据可保证判断故障区段的准确性;最后,根据时间轴中各点与线路长度间的线性关系得出以两个时间轴为基准的两个测距结果,并将测距结果取平均值.算例仿真结果表明,所提方法正确可行、原理简单,适用于各种带T型分支的混合输电线路结构,且不受过渡电阻的影响.

为解决行波相关法中时间窗宽度不固定影响故障测距可靠性的问题,提出了一种基于小波包多尺度分析的多时间窗行波相关法.首先,利用最大相关系数选取最优小波基,使得小波包滤波效果达到最佳;其次,以最优小波基为基底将故障信号进行小波包的多尺度分解和重构,由于小波包自身的变换特性,重构后的正反向行波初始波头的宽度随着尺度的增大逐渐变宽,将初始行波波头宽度作为行波相关法的时间窗宽度,此时行波相关法成为一个多时间窗的相关算法;最后,将经包络线处理的单极性正反向行波进行相关算法故障测距.多次仿真分析表明,所提方法消除了时间窗不固定对测距结果的影响,且在不同的故障距离和过渡电阻下均适用.

Fault transient traveling wave of cable and overhead line hybrid transmission line has the characteristics of complex and variable propagation. To this end, this paper uses theoretical analysis and simulation verification to do the research of the mechanism of production and propagation characteristics of fault transient traveling wave of cable and overhead line hybrid line in depth. On this basis, the principle of single line traveling wave distance measuring principle for hybrid line is expounded and the influence of transition resistance, fault inception angle, fault type, fault position on the fault voltage traveling wave, current traveling wave propagation characteristics and combined traveling wave fault location precision is explored in detail. At the same time, the relationship between the fault current and the fault distance of cable-metal shielding layer single-terminal grounded line is calculated and analyzed. The transition resistance, initial phase angle, fault type have a significant impact on fault voltage traveling wave and current traveling wave amplitude of 220 kV cable-overhead-line hybrid line, but they have no effect on the time required to reach the first wave of the traveling wave;under different fault location, the time that the amplitude of fault traveling wave of hybrid line and initial row wave surge reach both sides of the line is different; the current traveling wave amplitude of the single end ground wire of the cable metal shield decreases with the increase of the cable part fault distance, that is nonlinear monotone decreasing characteristic.

为解决带T型支路的混合输电线路故障测距问题,结合故障行波在带T型支路输电线路中的传播特性,提出一种基于组合行波测距原理的T型输电线路故障测距方法.首先通过双端测距原理判断故障所在区间,然后利用单端测距原理得到故障距离.与传统T型支路故障测距方法主要适用于单一架空线路相比,该方法适用于带有T型支路的混合输电线路,可进一步提高测距精度.电力系统计算机辅助设计软件(Power Systems Computer Aided Design,PSCAD)仿真验证了该方法的有效性和实用性,满足对故障测距精度的要求,能够简单有效、准确可靠的得出测距结果.

For the traditional double ended traveling wave ranging technology, the two terminal clock of the line needs precise timing. A new doubleended traveling wave fault location method based optical fiber time synchronization was proposed by combining the double-ended traveling wave ranging measurement with the optical fiber communication technology. First, the wavelet modulus maxima theory was used to detect the time of reaching the two ends of the line and polarity of the initial traveling wave, and the fault line was judged according to the polarity. Then, after the initial traveling wave of the fault arrives at both ends of the line, the pulse signal was transmitted to the opposite end by the optical fiber channel, and the correlation algorithm was used to automatically detect the time when the pulse signal reaches the opposite end. According to the transmission delay of the optical fiber channel, the absolute time of the initial traveling wave to reach the ends of the line was determined. Finally, the fault distance was determined by the dual end range method. The simulation results verify the feasibility of the method. The research results have high engineering application value.

To solve the problems existing in automatic measuring instrument of vehicle overall dimension in China market, an automatic measuring technology for overall dimensions of motor vehicles with infrared light curtain based on CAN bus was proposed in this paper, which can solve the problems prevalent in existing outline instrument made in China and abroad like poor dynamic response, large measurement error, which can realize rapid and accurate automatic measurement of vehicle overall dimensions. This instrument has passed the test of the Communication Safe Product Quality Supervision & Inspection Center of the Ministry of Public Security, the test precision can meet the requirement of relevant state standards.

考虑10 kV配电线路多分支、网络复杂的结构特点,首先建立常见的树枝状分支结构模型,针对T型架空线路结构,提出故障初测速度的概念;然后通过比较分析初测速度与实际波速度间大小关系,提出基于波速度比较的架空线故障选段方法;最后依靠双端行波测距方法,确定具体故障位置.PSCAD仿真结果证明,所提定位方法能有效确定故障区段,并准确定位故障位置,满足定位可靠性要求.

针对行波相关法时间窗不固定导致单端行波故障测距可靠性低的问题;提出将小波包和包络线结合的新方法.首先利用db1小波基对故障行波信号进行小波包多尺度的分解重构,验证了在不同尺度下正反向行波初始波头的宽度都是相同的;以正反向行波初始波头的宽度作为行波相关法中时间窗宽度,使时间窗宽度成为一个定值.其次,利用包络线把正反向行波中前两个不同极性的波头变为单极性波头,最后通过相关算法处理实现单端行波故障测距.所提方法使行波相关法中的时间窗宽度不再受故障距离、过渡电阻等因素的影响,且经包络线处理后的正反向波避开了相关函数出现多余极值.经PSCAD和MATLAB仿真分析,与传统行波相关法相比,所提方法明显提高了单端故障测距的可靠性.

针对变电站35 k V电缆-架空线出线不同位置发生单相接地故障时,对不同线路金属护层电流初始行波特性进行研究.利用PSCAD、MATLAB仿真软件进行仿真分析,结果表明小电流接地系统单相接地故障发生在电缆位置或者架空线位置时,无论是单芯电缆还是三芯电缆它们的金属护层电流初始行波极性会有明显的区别,对小电流接地系统单相接地故障选线有一定的参考价值.

In order to improve the ranging accuracy of traditional overhead line and cable hybrid transmission line,fault travelling wave propagation process in hybrid transmissions line is analyzed in detail.And then a combination travel ling wave fault location method is proposed for hybrid transmission line.First,fault location algorithm based double terminal travelling waves was applied to find out the failure zone.Then,it identified the source of the reflected travelling wave to each bus.Finally,the fault distance was calculated by single terminal method.The fault distance of 500 kV hybrid transmission line calculated by combination travelling wave fault location method indicates that the combination travelling wave fault location method is more accuracy than traditional fault location method,which can be applied to the practical uses.

It has a complicated and variable feature of fault transient traveling wave in cable and overhead line hybrid transmission line. Theoretical analysis and simulation method have been used to study the propagation characteristics of fault transient traveling wave in cable and overhead line hybrid line. The principle of single line traveling wave method for hybrid line is expounded and the influence of phase inception angle, transition resistance, fault type, fault position was studied. Then, combined traveling wave fault location precision is researched. Meanwhile, it built the relationship between transient fault current and fault distance. The above factors have a significant impact on transient voltage and current wave. But they have no effect on the time required to reach the first wave of the traveling wave. The combined travelling wave fault location method has good accuracy for overhead line-cable hybrid transmission line.

For the non‐effectively earthed system ,this paper propose a method of using neural network to solve the problem of fault line selection .This method extract real and imaginary parts of transient frequency to use the BP neural network to find the fault line .First ,a simulation model of non‐effectively earthed system was put up by ATP‐EMTP software ,to simulate differ‐ent fault distance ,transition resistance and fault initial angle in the model to obtain training sam‐ples and testing samples .Second ,MATLAB was used to train the BP neural network model .At last ,the trained neural network was used to find the fault line .The simulation proved that the method can solve the problem of line selection of the non‐effectively earthed system .

在光伏并网发电系统中孤岛检测对电网安全起着重要作用,而各种常见的主动式和被动式孤岛检测方法也是种类繁多,各有优点和缺点.其中衡量孤岛检测方法优劣的一个重要的指标就是总谐波畸变率(THD),为了降低总谐波畸变率对电网造成的危害,此文对主动式孤岛检测方法进行 分析研究和仿真验证,提出了几种减小总谐波畸变率的方法,并通过对仿真结果的对比,证明改进方法降低了总谐波畸变率,从而对并网电流质量的提高和居民用电安全性的改善提供了可靠的依据和途径.