积灰对输电线路导线电晕特性影响的电晕笼试验分析

在同一气候条件下,同一档距的电晕特性主要由导线高度和导线表面状况决定,这两者受当地各种气候环境影响。西北地区干旱而且多灰,这可能对750kV线路电晕特性有较大的影响。为了解这一影响,利用国家电网交流特高压试验基地电晕笼,模拟好天气(干燥导线)和雨天(淋雨)情况,对750kV积灰和光洁导线(6×400mm)在不同试验电压(不同表面场强)下的无线电干扰和可听噪声进行了试验测量。结果表明:在750kV示范工程设计的导线表面场强范围内,对于干燥导线,积灰导线产生的无线电干扰和可听噪声值均大于光洁导线所产生的,并且无线电干扰受影响严重,0.5MHz时无线电干扰差值可达20dB;在淋雨情况下,光洁和积灰导线电晕产生的无线电干扰差别不明显,但噪声差别明显,淋雨情况下积灰导线电晕产生的可听噪声约大光洁导线5～8dB。在试验导线表面场强达到一定程度后,积灰对导线电晕特性的影响逐渐减小。     

利用随机模型建模分析特高压交流输电线路的无线电干扰特性（英文）

For developing ultra-high voltage(UHV) AC power transmission systems,it is important to precisely estimate and to limit the radio interference(RI) level of power lines.Based on the stochastic characteristics in amplitude and repetition rate of induced corona current,by using the probability theory and mathematical statistics,we establish a stochastic model for the wide-sense stationary random process of corona discharges.Then combining the stochastic model with model-propagation-analysis method,the RI levels under three-phase UHV AC transmission lines are calculated.The results of the calculation based on stochastic model method and International Council on Large Electric Systems(CIGRE) excitation function are compared with that based on semi-empirical method and some other excitation functions.The stochastic model based on different excitation functions is also adopted to simulate the RI levels under finite test lines with two opened terminations.The results indicate that with the same average maximum gradient on conductor surface and the same conductor type,the number of corona discharge per unit length is one of the main reasons that causes the difference between different excitation functions.It is also concluded that for a long test line,the effect of standing wave on RI field strength is negligible in the middle of the line,but obvious near both terminations: for a 10-km line,the maximum difference in RI field strength is 2.78 dB,between the peak value of the standing wave near the ends and the steady value near the middle of the line.     

考虑经济损失期望的电压暂降分层分级治理方法

电压暂降因其给敏感用户带来的经济损失和社会影响而广受关注。电压暂降的治理涉及到系统、用户、设备3个层次的“责权利”,一直以来在治理上投入产出比不尽人意,尚未形成系统全面的治理体系。本文首先从不同层次分析研究了电压暂降发生、传播、危害的机理及影响因素,提出了一种考虑经济损失期望的敏感负荷分级方法与标准,该方法基于场景法生成电压暂降特征量,结合综合过程免疫时间对敏感负荷经济损失进行分级;其次,从电压暂降事件预防、设备持续运行、损失降低等方面综合对比了各种治理手段,并建立了基于敏感负荷分级的电压暂降治理体系,为配电网运行管理部门与电力用户选择合理经济的降低电压暂降损失的方案与措施提供参考。