Quan S.,China Electric Power Research Institute |
Xie L.,China Electric Power Research Institute |
Gu L.,China Electric Power Research Institute |
Cao J.,China Electric Power Research Institute |
And 2 more authors.
Dianwang Jishu/Power System Technology | Year: 2014
Due to interaction among electric fields the corona discharge is more hazardous for the secure operation of 1 000 kV UHVAC double circuit transmission lines on the same tower. The computational results of electric fields of jumpers and fittings for the demonstration project of 1 000 kV UHVAC double circuit transmission lines on the same tower show that the structure of the jumper and fittings should be optimized. To obtain the corona discharge characteristics of optimized jumper and fittings, the experimental investigation for corona discharge characteristics of cage-type and aluminum tube-type of rigid jumpers with different structures is carried out by ultraviolet imager to find the jumpers and fittings with obvious discharge traces to determine the discharge position and the trail value of corona inception voltage. Three-dimensional finite element method is utilized to establish the simulation model to calculate electric field strength and analyze the reason to lead to corona. Results of this research not only validates the effectiveness of the research approach for corona discharge characteristics, but also shows that the optimized jumpers and fittings can effectively decrease the electric field strength and well prevent the occurrence of corona. According to the research results, the recommended rigid jumpers and the matched connecting fittings can meet the operational requirement of UHVAC double circuit transmission lines on the same tower and have been applied in the design and construction of the demonstration project.
Gao X.,Shandong Electric Power Research Institute |
Su X.,Wuhan Power Supply Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2016
Conventional single-ended traveling wave fault location method exists inaccurate remote location problem. A new single-ended traveling wave solution is presented. The fundamental principle is that there exists phase difference between the fault point voltage before fault and the initial travelling wave voltage and the absolute value of the correlation coefficient between the two is 1.By measuring the pre-fault and after fault voltage and current the initial traveling wave and voltage of the transmission line can be obtained. Of all these absolute correlation coefficients, the one of the largest value is the distance of the fault point. Compared with the traditional traveling wave solutions, the new method can get the fault distance accurately even when the fault point is near the opposite bus bar. © 2016, Power System Protection and Control Press. All right reserved.
Zeng A.,Changsha University of Science and Technology |
Qin X.,Wuhan Power Supply Corporation |
Wang Y.,Changsha University of Science and Technology |
Pan H.,Changsha University of Science and Technology
International Journal of Advanced Mechatronic Systems | Year: 2012
Traditional double-terminal travelling wave protection schemes are unable to satisfy the requirement of power systems stability and economy. In order to solve these problems for extra high voltage (EHV) transmission lines protection, a novel non-unit transient protection based on HHT energy spectrum is developed. The travelling-wave characteristics between internal faults and external faults are analysed. The main difference is that the travelling wave high frequency components energy caused by the internal faults is larger than that caused by the external faults due to the influences of line trap and bus-to-ground capacitance. Intrinsic mode functions (IMF) of travelling wave are extracted by the empirical mode decomposition (EMD). And then Hilbert-Huang transform (HHT) is utilised to calculate the corresponding instantaneous frequency of each IMF component to obtain energy spectrum. Finally, the energy spectrum is applied to distinguish the internal and external fault. EMTP simulation results show that, under different fault conditions, the novel scheme can distinguish reliably the internal faults from external faults and protect the whole transmission line with high sensitivity. Copyright © 2012 Inderscience Enterprises Ltd.
Lu N.,Wuhan University of Technology |
Wu B.-L.,Xuchang Senior Technical School |
Liu Y.,Wuhan Power Supply Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011
In order to improve the precision of short-term load forecasting, and aiming at the parameter selection of traditional SVM in load forecast this paper proposes a new load forecasting model, i.e., using the improved adaptive particle swarm optimization(PSO) for seeking the optimal parameters of support vector machine(SVM) model. The classical PSO is a global optimization algorithm. Based on it, the improved PSO(FAPSO) is proposed and its convergence tests are conducted, and then the SVM model based on the FAPSO optimization is applied to the short-term power load forecasting. The simulation results show that the adaptive particle swarm optimization-based SVM load forecasting model is more accurate than the traditional SVM model and has certain practical value.
Li-Song T.,Wuhan Power Supply Corporation |
Wei-Xuan C.,South China University of Technology
Applied Mechanics and Materials | Year: 2013
The partial discharge (PD) detection systems are often vulnerable to strong external interferences, and sometimes the PD signals are submerged in noises (white noise for example) completely. So the signals acquired must be preprocessed to obtain the reliable PD information. While there are many methods for white noise denoising, mostly are not very suitable for partial discharge. The wavelet transform (WT) coefficient of PD and white noises have different spread characteristics in different WT scales. Based on the Information Theory, The Minimum Information Description Length (MDL) criterion is a optimization strategy, a small amount of signal parameter is requried to the PD signals representation, the paper proposes a wavelet spatial correlation algorithm to partial discharge denoising based on MDL criterion: optimal wavelet function is selected based on MDL, then have the white noise reduced in WT, the algorithm has wonderful virtues such as free from any parameters estimation about noise, free from presetting threshhold and threshold chooseing behavior, so the algorithm is highly adaptive. Large amount of experimental results illustrate that the method presented in this paper are efficient and feasible and outperforms other general method of PD noise reduction. © (2013) Trans Tech Publications Switzerland.