辽宁地区雷电活动与输电线路雷害故障特点

利用雷电定位系统数据对辽宁地区雷电活动时间和空间特性进行了分析,对近10年来辽宁电网220 kV及以上电压等级架空输电线路雷害故障情况进行了统计,并有针对性地提出了输电线路防雷建议.     

直击雷对变电站控制室内弱电设备的影响

章说明了雷直击变电站时如何对其控制室内的弱电设备造成干扰,并分析了雷击控制室防雷系统时,影响室内回路中暂态感应电压幅值的各种因素。     

电站弱电系统防雷研究

针对近年来发电厂、变电所使用的微机保护和综合自动化系统发生的雷害事故,讨论了低压电源系统的雷电干扰,以及雷电对二次回路等弱电系统的干扰。分析了雷电对微机保护、综合自动化系统的干扰方式、干扰的途径。深入研究了在弱电系统防雷上存在的缺陷和不足,提出了弱电系统防止雷电干扰的技术措施。     

Maximum lightning overvoltage along a cable due to shielding failure

This paper analyzes the maximum lightning overvoltage due to shielding failure along a cable inserted in an overhead line. The cable is protected by surge arresters at both ends and the maximum voltage appears normally somewhere along the cable. The maximum voltage can for severe cases of lightning overvoltages be found by calculating the voltage at a limited number (e.g. 10) of equidistant positions along the cable.     

System wide MV distribution network technical losses estimation based on reference feeder and energy flow model

This paper presents an integrated analytical approach to estimate technical losses (TL) of medium voltage (MV) distribution network. The concept of energy flow in a radial MV distribution network is modelled using representative feeders (RF) characterized by feeder peak power demand, feeder length, load distribution, and load factor to develop the generic analytical TL equations. The TL estimation approach is applied to typical utility MV distribution network equipped with energy meters at transmission/distribution interface substation (TDIS) which register monthly inflow energy and peak power demand to the distribution networks. Additional input parameters for the TL estimation are from the feeder ammeters of the outgoing primary and secondary MV feeders. The developed models have been demonstrated through case study performed on a utility MV distribution network supplied from grid source through a TDIS with a registered total maximum demand of 44.9 MW, connected to four (4) 33 kV feeders, four (4) 33/11 kV 30 MVA transformers, and twelve (12) 11 kV feeders. The result shows close agreement with TL provided by the local power utility company. With RF, the approach could be extended and applied to estimate TL of any radial MV distribution network of different sizes and demography.     

人工引雷及其在雷电防护中的应用

自１９８９年以来，利用火箭－导线技术在我国南方和北方进行了多次人工引雷试验，共获得２５次成功。其中北方１４次，南方１１次。南、北方的人工引雷特性存在着显著差异。本文总结了这些试验的一些主要结果，探讨了人工引雷在雷电防护中的应用，指出人工引雷技术是检验雷电防护器件及设施和促进雷电防护技术发展的有力工具。     

大型整流变压器雷电冲击耐受试验

介绍了大型整流变压器雷电冲击耐压试验方法,并利用HIAS742高分辨率脉冲分析系统对变压器试品的试验结果进行了判断和分析,为今后大型整流变压器的雷电冲击耐压试验提出了一些建设性意见。     

230 MHz无线负荷控制信道在配电自动化中的应用

介绍了２３０ＨＭｚ无线信道应用于配电网自动化系统,实现馈线自动化和配电变压器监测的方案,讨论了在配电网自动化中采用无线信道的可行性,并结合工程实际提出了无线电应用于电网自动化应注意的问题。     

弱电设备的雷击浪涌综合保护

弱电设备主要是与工作和生活的现代化密切相关的通讯系统、控制系统、计算机系统、报警系统中的重要部分,它的安全稳定运行至关重要。但弱电设备的绝缘强度低,耐受过电压和过电流的能力差,对电磁干扰敏感。因此弱电设备的防雷保护非常重要。     

从建筑工程的防雷设计谈“消雷器”

本文系在北京市避雷装置安全检测中心组织的“消雷器”研讨会上的发言。首先简述了建筑工程防雷设计概况，回顾了其演变。之后谈了对“消雷器”的看法和“消雷器”与避雷针在实际应用中的价格比较。最后谈了防雷设计人员应该怎样正确进行设计。     

Identifying Single-Phase-to-Ground Fault Feeder in Neutral Noneffectively Grounded Distribution System Using Wavelet Transform

A scheme of single-phase-to-ground fault feeder identification in distribution networks with the application of a wavelet transform technique is presented in this paper. The scheme uses zero-sequence current traveling waves to identify the faulted feeder, and the busbar residual voltage to determine an event caused by fault or switch operation. The current traveling waves measured by zero-sequence current transducers are decomposed using wavelet multiresolution analysis. The local modulus maxima of the wavelet transform are extracted to determine the time of the initial traveling wave. The wavelet transforms on all feeders at the time are compared in magnitude and polarity with each other to identify the faulted feeder. The feeder identification is independent of the network neutral-point grounding mode. The proposed scheme was implemented and verified using Electromagnetic Transients Program (EMTP)-generated signals. The scheme proved to be robust against transients generated during normal events, such as feeder energizing and de-energizing as well as capacitor bank switching.     

Lightning performance assessment of Hellenic high voltage transmission lines

A methodology for assessing the lightning performance of Hellenic high voltage transmission lines has been developed. Its main advantage is that the analysed transmission line is divided into regions and the analysis is conducted separately for each one region, taking into account the individual characteristics, which exist in each one of them. The developed approach intends to offer more accuracy in the assessment of lightning performance of Hellenic high voltage transmission lines and of similar lines, where they run at the same time through a plain region, a coastline and/or a mountainous region. The aims of the paper are to describe in detail the proposed methodology and to present results obtained by its application on operating Hellenic transmission lines of 150 and 400 kV. The computed results are compared with the results produced by another software tool published in the technical literature and with the real records of outage rate showing a good agreement. The presented methodology, which is coded in a comprehensive computer program, can be proved valuable to the studies of electric power systems designers intending in a more effective lightning protection.     

雷击高压直流线路杆塔仿真研究

雷击高压直流线路杆塔时,由于预先存在的直流工作电压对杆塔间隙的电气强度可能带来较大的影响,因此线路的耐雷性能与交流情况的不同.作者建立了雷击直流线路杆塔时的线路模型、杆塔模型、闪络判据等,采用仿真软件PSCAD/EMTDC对雷击直流线路杆塔的过电压和闪络进行了仿真分析,讨论了各种运行方式下直流工作电压对线路耐雷性能的影响.仿真分析结果表明: 500kV单极-金属回线运行与双极±500kV运行时,正极线的耐雷水平基本相同,负极线的耐雷水平远高于正极线;-500kV单极-金属回线运行时线路的耐雷水平最高.     

Dynamic fault location method for distribution networks with distributed generation

This paper presents a new analytical time-based fault location algorithm for radial distribution networks with synchronous generators used for distributed generation (DG). The algorithm uses the voltage and current samples recorded at the main feeder head along with the scheduled injected active and reactive powers by the network synchronous generators to estimate the fault location. A full order synchronous machine model has been used to consider dynamic behaviour of the DG plants during fault transients. The algorithm, therefore, uses time domain analysis and is dynamic in the sense that it uses the updated synchronous machines and network data at each time step. The algorithm is implemented in two sequential steps. In the initialisation step, by using the measured pre-fault voltage at the main feeder head and scheduled power injections by the DG plants, a pre-fault load flow calculation is performed to evaluate different parameters of the synchronous generators, initial values of the network node voltages, line section currents, loads and capacitive charging currents. In the second step, the numerical fault location algorithm is performed by moving the data window from the pre-fault to a post-fault cycle. The accuracy of the proposed algorithm has been validated by several simulated fault studies carried out on a 205-node 20 kV practical radial distribution feeder. The results have shown remarkable accuracy in fault location when considering only the current and voltage measurements at the main feeder head have been used.     

Transient voltage stress of 400 kV urban system evaluated by numerical calculations

Overhead lines, high voltage cable systems and substations are important elements of the high voltage network. More and more close combinations of these elements are used in urban networks. This leads to new transient situations and a more complex transient behaviour in case of lightning or switching events. Additionally the requirements of a constant power supply ask for new efforts to predict impacts caused by interruptions.     

The electrical breakdown characteristics of oil-paper insulationunder steep front impulse voltages

Disconnecting switch operations in gas insulated equipment cause transient voltages with risetimes as steep as 5 to 20 nanoseconds and magnitudes as high as 2.5 pu. There is very little information on the effect of these transients on oil-paper insulated equipment. There have been reports, however of transformer and bushing failures caused by these transients. The electrical breakdown characteristics of oil-paper insulation under steep front impulse were studied in this project, which was co-sponsored by the Canadian Electrical Association and BC Hydro. V ₅₀ (50% breakdown probability voltage) breakdown data was obtained with steep front (10 ns/2500 μs), lightning and switching impulse waveforms. Insulation breakdown voltage vs breakdown time (V-t) data and multiple impulse breakdown data were obtained with the steep front impulse waveform. The V₅₀ results showed that the breakdown strengths were lower for steep front impulses than for lightning impulses. The multiple impulse breakdown results showed that oil-paper insulation breakdown strength can be lower than 100 kV/mm. These results are alarming, since they suggest that oil-paper insulated equipment subjected to steep front transients will fail at voltages below the lightning impulse design level (BIL). The volt-time data had a discontinuity. The breakdown process at risetimes below about 50 ns was different from the breakdown process at risetimes above 50 ns     

感应过电压对输电线路耐雷水平的影响

文章分析了雷击输电线杆塔时产生的感应过电压通过场线耦合机制对输电线路耐雷水平的影响.分析和仿真计算结果都表明,感应过电压对耐雷水平的影响不可忽略.比较了计算感应过电压的几种典型方法的优缺点后,推荐其中一种简化的方法,并将该方法应用到实际防雷计算中进行了验证.     

Optimal integrated planning of MV-LV distribution systems using DPSO

A new technique for optimal planning of MV and LV segments of a distribution system is presented in this paper. The main goal is to find optimally distribution transformer and substation locations and ratings, as well as, the route and type of Medium Voltage (MV) and Low Voltage (LV) feeders. The proposed technique is applicable to both uniform and non-uniform load densities areas. In this method, the planning area is divided into regions with relatively uniform load density such as urban, semi-urban, sub-urban. Each of regions is divided into zones, called LV zone. Each LV zone is supplied by an MV/LV transformer. The dimensions of LV zones are found based on the average load of each region. The placement and rating of MV/LV transformers, the type and route of LV conductors in an LV zone all depend on its loads’ location and power. Regarding the placement and rating of MV/LV transformers in planning area and the space of regions, the dimensions of a zone which is supplied by a HV/MV transformer, called MV zone, is determined. Additionally, the location and rating of HV/MV transformers as well as the feeder's routes and types are calculated. Since the dimensions of an LV zone influence the associated length of MV feeder, the MV feeder cost needs to be included in the total cost associated with the LV zone. This requires the MV feeder type to be known to calculate the corresponding cost. However, the MV feeder type is determined as an output from MV zone planning. As a result, an iterative based method is proposed to consider this common element in computations to develop integrated planning of both LV and MV zones. It is observed that the iterative technique quickly converges to the same results as the exhaustive search method.Discrete particle swarm optimization (DPSO) method is employed for solving the planning problem. The results are compared with nonlinear programming, genetic algorithm and exhaustive search methods. It is observed that DPSO is as accurate as the exhaustive search method for integrated planning of MV-LV distribution systems while its computation time is significantly lower.     

基于降低雷电流最大陡度线路防雷新方法的研究

雷电流陡度大是雷电破坏的主要原因之一。采用人为的手段降低雷电流陡度,可以减少雷电对杆塔等雷击点的破坏作用。提出了限陡避雷针的新理论,深入讨论了它的作用机理。通过暂态仿真软件ATP对模型进行了定量研究,结合大电流冲击发生器的模拟实验。证明了限陡避雷针的使用,能有效地降低雷电流陡度,降低塔顶电位。为电力设备防雷又提供了一种新的手段。     

High-impedance fault detection in distribution networks with use of wavelet-based algorithm

A new simple and effective algorithm of arcing fault detection in distribution networks with the application of a wavelet transform technique is presented in this paper. The protection algorithm developed observes the phase displacement between wavelet coefficients calculated for zero-sequence voltage and current signals at a chosen high-level frequency. The final decision in regards to feeder switching off (or alarm issuing) is met either with a deterministic logic scheme or with the use of a neural net trained especially for that purpose. The developed wavelet-based high-impedance fault (HIF) detector has been tested with Electromagnetic Transients Program-Alternative Transients Program (ATP)-generated signals, exhibiting better performance than traditionally used algorithms and methods. The protection method proposed may be used for HIF detection independent of the network neutral-point grounding mode. The scheme proved to be robust against transients generated during normal events such as feeder energizing and de-energizing as well as capacitor bank switching.