Time filter

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Chao D.,East Inner Mongolia Electrical Power Company | Yang J.,Puyang Power Supply Company | Su S.,Huazhong University of Science and Technology | Shi D.,Huazhong University of Science and Technology
Dianwang Jishu/Power System Technology | Year: 2011

The information on faults occurred in Puyang distribution network is extracted, and analysis results of the information shows that the time series of faults possess evident long-term self-correlation and its probability distribution shows up power-law distribution characteristics, so the faults occurred in Puyang distribution network possess self-organized criticality (SOC). Weather factor greatly influences on faults of distribution network, and according to the analysis of the fault causes it is found that the SOC of precipitation phenomena in atmosphere system is the determinative factor of SOC of faults occurred in distribution network of this region.


Yang F.,Chongqing University | Liu Z.,Chongqing University | Luo H.,East Inner Mongolia Electrical Power Company Ltd | Liu X.,Zibo Power Supply Company | He W.,Chongqing University
IEEE Transactions on Magnetics | Year: 2014

In this paper, the meshless method is used to calculate the ion flow field under the high-voltage direct current transmission lines for the first time. The meshless local Petorv-Galerkin method is employed to solve Poisson's equation, and the upwind meshless method is applied to solve the current continuity equation. After the validity of the method is tested, the distribution of electric field and ion current density at ground level with different temperature and altitude of the transmission lines are discussed. The results show that the electric field and the current density are greater when the temperature and altitude are higher. © 1965-2012 IEEE.


Huang Y.,Wuhan University | Le J.,Wuhan University | Mao T.,Wuhan University | Luo H.,East Inner Mongolia Electrical Power Ltd Company | Liu K.,Wuhan University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2016

This paper presents a novel method to online identify detuning components of the filter at the DC side in HVDC system. This method only needs to measure the current of each branch of the filter and analyzes the harmonic component, and then identifies the detuning component through calculating the change rates of several harmonic currents. The principle and the implementation of the proposed method are presented, and the theoretical formula is deduced about the relationship between the harmonic current change rate and the detuning ratio of different elements.. Thereafter, this paper proposes the criterions to identify the filter detuning, detuning components in series and in parallel of the filter, and the detuning degree. Simulation results of single-tuned and double-tuned filters show the correctness and effectiveness of the proposed method. This method can expand the original functions of the traditional filter with simple modification. It can realize the online identification of detuning components accurately and rapidly, and has good application prospect. © 2016, The editorial office of Transaction of China Electrotechnical Society. All right reserved.


Mao T.,Wuhan University | Le J.,Wuhan University | Huang Y.,Wuhan University | Luo H.,East Inner Mongolia Electrical Power Ltd Company | Liu K.,Wuhan University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2016

Measurement accuracy of AC harmonic voltage is important to ensure the operation safty of high voltage DC (HVDC) system and to validate the effectiveness of the AC filter design. This paper proposes a novel method to measure the harmonic voltage on AC side of HVDC system. The principle is measuring the current of the AC filter, and calculating the harmonic voltage on AC side according to the harmonic analysis from the measured current and the given impendence-frequency characteristic of the filter. The effects of AC filter component detuning on the measurement of harmonic voltage are studied in detail. The theoretical expressions for a double-tuning AC filter are deduced, to describe the relationship between the measurement error of harmonic voltage and the detuning degree of the filter parameters. The influence of detuning degree on the measurement of individual harmonic voltage is also analyzed. The relative sensitivities of the harmonic voltage measurement error to the filter component parameters are studied. Finally, the proposed method is verified by the simulation and lab test. © 2016, The editorial office of Transaction of China Electrotechnical Society. All right reserved.


Luo H.,East Inner Mongolia Electrical Power Ltd Company | Huang Y.,Wuhan University | Jiang G.,East Inner Mongolia Electrical Power Ltd Company | Kang K.,East Inner Mongolia Electrical Power Ltd Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2015

The online identification of the filter detuning elements has an important practical value for improving the reliability of the HVDC system. This paper presents a novel method for online identification of the detuning elements of the DC-side filter of the HVDC system. The method only needs to measure and extract the harmonic components from the current that through the single-tuned filter. Weather the filter has detuned or not can be known by the analyzing the change rate of the harmonic current under resonant frequency. In the situations that the filter has detuned, the detuned elements can be identified by calculating the ratio of the change rates of several special harmonic current. This method can be realized based on a simple modification of the traditional DC-filter, and thus the function of the filter is expanded. This paper presents the principles of the proposed method and the simulation results of the application of this method on different filters verify the validity and effectiveness of the proposed method. ©, 2015, Power System Protection and Control Press. All right reserved.


Luo H.-W.,Wuhan University | Luo H.-W.,East Inner Mongolia Electrical Power Ltd Company | Cai W.,Wuhan University | Le J.,Wuhan University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

The power line channel modeling and the analysis of influence factors are the theoretical basis of high-speed data transmission over the power line. The paper proposes a channel modeling approach of the power-line communication channel based on the information nodes, and then presents the influence laws of the factors such as the length between transmitter and receiver, branched line lengths, branched load impedances and number of branches on channel transmission characteristics. The paper emphatically analyzes the influence of attenuation amplitude induced by these factors. It is seen that the power-line input impedance is fixed at signal attenuation peak frequency point. The conclusions provide the necessary theoretical basis for power-line communication modulation method.


Mao T.,Wuhan University | Le J.,Wuhan University | Huang Y.,Wuhan University | Luo H.,East Inner Mongolia Electrical Power Ltd Company
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2015

Fourier decomposition is applied to the DC-side filter current measurements of HVDC transmission system to obtain the harmonic currents of different orders and the impendence-frequency characteristics of the filter is adopted to calculate the corresponding harmonic voltages. The relationship between the error of harmonic voltage measurements and the parameter mismatch is deduced for the normal single-tuned filter, and the effect of detuning degree on the harmonic voltage measurement is analyzed for different elements, as well as the sensitivity of harmonic voltage measuring error to the filter parameter mismatch. The results of simulative calculation show the correctness and effectiveness of the proposed method. © 2015, Electric Power Automation Equipment Press. All right reserved.


Yang F.,Chongqing University | Cheng P.,Chongqing University | Luo H.,Maintenance Branch of East Inner Mongolia Electrical Power Company Ltd | Yang Y.,Chongqing University | And 2 more authors.
Applied Thermal Engineering | Year: 2016

Aiming at the overheating problem of power cable joints, which is mainly caused by great contact resistance and unqualified installation, a 3-D electromagnetic-thermal model for power cable joint was set up, and a method was presented to deal with the influence on the thermal distribution of power cable joint caused by the contact resistance RJ. Example calculation was described in details, and the result shows that the cable conductor temperature along the axial direction exponentially decreases within the range of 2 m away from the cable joint center. The numerical results agreed with the analytical results and measured results within 5%. Then the influence rules of contact coefficient k, ambient temperature Tamb and load current I on cable joint thermal distribution were investigated. Finally, the piecewise functions of the cable temperature difference ΔT, k and I were developed to evaluate the RJ of the power cable joint by regression analysis, which can be used to evaluate whether a power cable joint is qualified or not, and the correlation coefficients are greater than 0.999. Results indicate that to ensure the lower conductor temperature of cable joint than that of cable body, the k should be less than 2.7, and the relative error between the proposed evaluation method and the simulation method is within 2%. © 2015 Elsevier Ltd. All rights reserved.


Du C.,North China Electrical Power University | Qi B.,North China Electrical Power University | Xie H.,East Inner Mongolia Electrical Power Company Ltd | Lv H.,Beijing Sifang Automation Co
MATEC Web of Conferences | Year: 2015

Electric vehicles are the most potential transports in the future. However, the large scale of charging facilities will make a great influence on gird. There is a need to make a research on the construction of charging facilities. Based on the power demand characteristics of electric vehicle charging, distribution network capacity, charging system performance and other aspects, this paper mainly researched the deployment strategy of charging piles. First, the authors built up a model with characteristics of charging power demand of electric vehicle and a model of charging service system. The characteristic of daily load curve is analyzed. Second, based on these works, the authors designed the progress of strategy making. At last, the progress was verified by the actual use case. © Owned by the authors, published by EDP Sciences, 2015.


Mao T.,Hubei Engineering University | Le J.,Hubei Engineering University | Huang Y.,Hubei Engineering University | Luo H.,East Inner Mongolia Electrical Power Ltd Company
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2015

Accurate and effective measurement of the AC side harmonic voltage of HVDC transmission systems is an important basis for the research and analysis of the correctness and validity of the design and operation of AC filters, and is also the premise to master the real-time harmonic condition of HVDC systems. A novel method that can solve the problem of lacking of high cost-effective harmonic voltage measurement means in HVDC systems was proposed in this paper. The principle of this method is to measure the current of the AC filter of HVDC power systems, and the harmonic voltage on the AC side can be calculated conveniently according to the harmonic analysis results of the measured current and the component parameters or known impendence-frequency characteristics of the filter. This method can be performed on the basis of traditional AC filters with simple modification and can achieve high accuracy harmonic voltage measurement, thus expands the functions of the AC filter. The principle of the proposed method and the harmonic voltage calculation method were presented, the performances of harmonic voltage measurement utilizing different filters were compared, and influences of the changes of AC filter parameters and the measurement accuracy of the current transformer on the measurement of harmonic voltage were researched. The correctness and effectiveness of the proposed method were verified by simulations. ©2015 Chin. Soc. for Elec. Eng.

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