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Lu N.,Wuhan University of Technology | Wu B.-L.,Xuchang Senior Technical School | Liu Y.,Wuhan Power Supply Company
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.


Xia R.,State Grid Electric Power Research Institute of China | Zhao J.-K.,State Grid Electric Power Research Institute of China | Ouyang B.-H.,State Grid Electric Power Research Institute of China | Jiang W.,Wuhan Power Supply Company | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2010

In order to detect and diagnose the dielectric property at damped AC (DAC) voltages in field experiments and condition maintenance in its application for 110 kV XLPE power cable systems in China, and to accumulate measurement experience, the principal of DAC voltage generation, DAC voltage properties and on-site detections including voltage withstand test, partial discharge (PD) detection, PD location and dielectric loss measurement at DAC voltages were studied. Moreover, functions and composition of typical DAC testing system (OWTS) for HV XLPE power cables were analyzed. In addition, the first trial of dielectric property detection and healthy status diagnosis for the two 110 kV XLPE power cable circuits at home was introduced. Through theoretical analysis and on-site application, it is proved that this technique is suitable for on-site test and diagnosis of disconnected full-length power cable circuits including cables and accessories, by using DAC voltage instead of 50 Hz AC voltage and combined with multi-methods such as voltage withstand test, PD detection, PD location and dielectric loss measurement can overcome the shortages of available dielectric property detecting methods for HV XLPE power cables.


Tang Z.,Wuhan University | Zhou W.,Wuhan University | Zhao J.,China Electric Power Research Institute | Wang D.,Wuhan Power Supply Co. | And 4 more authors.
IEEE Transactions on Power Delivery | Year: 2015

This paper compares the application of the Weibull distribution and the Crow-AMSAA (C-A) model to the analysis of cable joint failures. The procedures on how to use the two models to analyze failure data and to predict the future number of failures have been described before the models are applied to a set of early failure data. The data, which include 16 failures and 1126 suspensions, were collected from a regional power-supply company in China. This paper proves that the Weibull distribution provides more reliable results in the analysis of early-failure data since it considers the time to failure of each event. Whilst the method is more straightforward and requires less information, applying the C-A model can yield confusing results if not handled carefully. When analyzing the events, using time as x-axis and using the cable joint population as an axis can complement each other. Separating those data into subsections and analyzing them independently can yield useful information. Recent failure data can better reflect the current state of cable joints. The results of this paper should help utility asset managers better analyze their past failure events. © 2015 IEEE.


Yang C.X.,Wuhan Polytechnic University | Liu K.P.,Wuhan University | Zheng X.,Wuhan Electrical Technical Power College | Wang D.X.,Wuhan Power Supply Company
Advanced Materials Research | Year: 2013

Parallel harmonic resonance is closely related to the singularity of a node admittance matrix. It was found that the smallest eigenvalue of the matrix defines the mode of parallel harmonic resonance. This paper applies eigenvalue theory and modal sensitivity analysis method to determine which network components contribute significantly to a harmonic resonance phenomenon. Case study results further confirm the theoretical correctness and effectiveness. Thus, this practical method not only provides significant measures for harmonic resonance manage, but also support theoretical and experimental bases for the component parameter design. © (2013) Trans Tech Publications, Switzerland.


Tang Z.,Wuhan University | Zhou C.,Glasgow Caledonian University | Jiang W.,Wuhan Power Supply Company | Zhou W.,Wuhan University | And 4 more authors.
IEEE Transactions on Power Delivery | Year: 2014

This paper proposes the use of the Cox proportional hazard model (Cox PHM), a statistical model, for the analysis of early-failure data associated with power cables. The Cox PHM analyses simultaneously a set of covariates and identifies those which have significant effects on the cable failures. In order to demonstrate the appropriateness of the model, relevant historical failure data related to medium voltage (MV, rated at 10 kV) distribution cables and High Voltage (HV, 110 kV and 220 kV) transmission cables have been collected from a regional electricity company in China. Results prove that the model is more robust than the Weibull distribution, in that failure data does not have to be homogeneous. Results also demonstrate that the method can single out a case of poor manufacturing quality with a particular cable joint provider by using a statistical hypothesis test. The proposed approach can potentially help to resolve any legal dispute that may arise between a manufacturer and a network operator, in addition to providing guidance for improving future practice in cable procurement, design, installations and maintenance. © 1986-2012 IEEE.


Jing X.,Wuhan Power Supply Company | Peng X.,Glasgow Caledonian University | Jiang W.,Wuhan Power Supply Company | Zhou W.,Wuhan University | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2012

Phase resolved partial discharge (PD) pattern recognition is a key step in on-line PD condition monitoring of cable systems. But in practical applications, voltage phase information is difficult to obtain. Lack of phase information presents a technical challenge when diagnostics is made. This paper presents a K-Means based autonomous phase resolved PD pattern recognition technique, including procedures of pulse extraction, coordinate transform, K-Means clustering, 'means' overlaying and PD pattern judgement. The method has been evaluated against 5 application examples and proved to be an effective technique to identify PD patterns and distinguish among corona discharge, internal discharge, surface discharge and interference signals.


Yang Z.,Wuhan University | Liu K.,Wuhan University | Le J.,Wuhan University | Wan Z.,CR11G Electrical Engineering Co. | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

To overcome the inherent shortcomings of the commonly used voltage/frequency droop control for distributed generators (DGs) in islanded microgrids, an improved droop control with a proportional-integral-derivative (PID) structure is proposed. The PID parameters are optimized using the fuzzy logical reasoning technology based on the variations of voltage and frequency. And then an adaptive fuzzy PID droop controller is designed to further reduce the oscillations of voltage and frequency due to disturbances from microgrids. The correctness and validity of the proposed fuzzy PID droop controller are verified by simulation. © 2013 State Grid Electric Power Research Institute Press.


Gao X.,Shandong Electric Power Research Institute | Su X.,Wuhan Power Supply Company
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 Company | 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.


Li-Song T.,Wuhan Power Supply Company | 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.

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