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Investigation of active rotor speed protection strategy for DFIG-based wind turbines with inertia control

Dianli Xitong Zidonghua/Automation of Electric Power systems 2015年第24期39卷 29-34and95页

作者： Ding, Lei Yin, Shanyao Wang, Tongxiao Liu, Jingli Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong University Jinan250061 China

Doubly-fed induction generator (DFIG)-based wind turbines with virtual inertia control can contribute to the primary frequency regulation and relieve the lack of system inertia caused by high penetration of large-scale wind farms. However, DFIG-based wind turbines will exit frequency regulation if the rotor speed falls below a definite value since the kinetic energy stored in the rotor is limited. This procedure and the subsequent rotor speed recovery will lead to a secondary frequency drop. In this paper, the characteristics of virtual inertia control and available kinetic energy released by DFIG-based wind turbines under different wind speed conditions are quantitatively analyzed. Then an active rotor speed protection strategy is proposed to make DFIG-based wind turbines gradually release the kinetic energy to avoid the secondary frequency drop. In the proposed strategy, a negative feedback control is adopted to release rotor kinetic energy, and its proportional and integrated parameters are set adaptively according to the operational states and capacity of the DFIG-based wind turbines. The validity and effectiveness of the proposed protection strategy is illustrated by case studies. © 2015, Automation of Electric Power systems Press.

关键词： Wind turbines

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A new automatic mass detection method for breast cancer with false positive reduction

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Neurocomputing 2015年 152卷 388-402页

作者： Xiaoming Liu Zhigang Zeng School of Automation Huazhong University of Science and Technology Wuhan 430074 China Key Laboratory of Image Processing and Intelligent Control of Education Ministry of China Wuhan 430074 China College of Computer Science and Technology Wuhan University of Science and Technology Wuhan 430081 China Hubei Province Key Laboratory of Intelligent Information Processing and Real-time Industrial System Wuhan 430081 China

Mass localization is a crucial problem in computer-aided detection (CAD) system for the diagnosis of suspicious regions in mammograms. In this paper, a new automatic mass detection method for breast cancer in mammographic images is proposed. Firstly, suspicious regions are located with an adaptive region growing method, named multiple concentric layers (MCL) approach. Prior knowledge is utilized by tuning parameters with training data set during the MCL step. Then, the initial regions are further refined with narrow band based active contour (NBAC), which can improve the segmentation accuracy of masses. Texture features and geometry features are extracted from the regions of interest (ROI) containing the segmented suspicious regions and the boundaries of the segmentation. The texture features are computed from gray level co-occurrence matrix (GLCM) and completed local binary pattern (CLBP). Finally, the ROIs are classified by means of support vector machine (SVM), with supervision provided by the radiologist׳s diagnosis. To deal with the imbalance problem regarding the number of non-masses and masses, supersampling and downsampling are incorporated. The method was evaluated on a dataset with 429 craniocaudal (CC) view images, containing 504 masses. Among them, 219 images containing 260 masses are used to optimize the parameters during MCL step, and are used to train SVM. The remaining 210 images (with 244 masses) are used to test the performance. Masses are detected with 82.4% sensitivity with 5.3 false positives per image (FPsI) with MCL, and after active contour refinement, feature analysis and classification, it obtained 1.48 FPsI at the sensitivity 78.2%. Testing on 164 normal mammographic images showed 5.18 FPsI with MCL and 1.51 FPsI after classification. Experiments on mediolateral oblique (MLO) images have also been performed, the proposed method achieved a sensitivity 75.6% at 1.38 FPsI. The method is also analyzed with free response operating characteristi

关键词： Mass detection Breast cancer Level set Local binary pattern Support vector machine

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Self-triggered Based Semi-global Consensus Tracking of Multi-agent systems with Input Saturation

Self-triggered Based Semi-global Consensus Tracking of Multi...

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第三十四届中国控制会议

作者： Xiaoling Wang Housheng Su Jiwei Li Xiaofan Wang Department of Automation Shanghai Jiaotong University and Key Laboratory of System Control and Information Processing Ministry of Education of China Shanghai 200240 P. R. China School of Automation Image Processing and Intelligent Control Key Laboratory of Education Ministry of China Huazhong University of Science and Technology Luoyu Road 1037 Wuhan 430074 P. R. China

ISBN: (纸本)9781467374439

Self-triggered control is a technique which can determine the next sampling instant by virtue of the last sampling information. Combining this technique and the low-gain feedback one, we investigate the consensus tracking of general linear multi-agent systems with input saturation and updating delays in this paper. Specific formulations of heterogenous updating delays and heterogenous sampling periods are acquired to guarantee the semi-global consensus tracking of multi-agent systems. Numerical simulations are provided to verify the main results.

关键词： Multi-agent systems Consensus Tracking Self-triggered Technique Input Saturation Low-gain Feedback Multi-agent systems sampling time tracking

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DC fault analysis of VSC-HVDC and DC cable protection principle

DC fault analysis of VSC-HVDC and DC cable protection princi...

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IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC)

作者： Pu Zhao Qing Chen Luhua Xing Key Laboratory of Power System Intelligent Dispatch and Control(Shandong University) Ministry of Education Jinan China Shandong University Jinan Shandong CN State Grid Shandong Electric Power Research Institute Jinan China

ISBN: (纸本)9781467381338

Voltage Source Converter (VSC) based HVDC (VSC- HVDC) transmission technology as a kind of new dc transmission, is attracting more and more research. VSCs are susceptible to cable short-circuit fault and ground fault. This paper focuses on the transient characteristics of electrical quantities in a two terminal VSC-HVDC system after the occurrence of short-circuit fault and ground fault. Equivalent circuits and equations are given to calculate the voltage and over-current in cable. Simulations are undertaken in PSCAD to verify the calculation results, and different fault points and fault resistances are considered. Due to the behaviors of DC voltage and cable over-current in faulty cable and non-faulty cable after the ground fault, a DC cable protection principle was proposed to determine the faulty cable and to decide fault within or outside the protected area.

关键词： Circuit faults Power conversion Power cables Capacitors Equivalent circuits Transient analysis

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The application of TCSC for damping inter-area oscillations

The application of TCSC for damping inter-area oscillations

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IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC)

作者： Jingli Liu Lei Ding Deyu Cai Zhiming Song Key Laboratory of Power System Intelligent Dispatch and Control Ministry of Education Shandong University Jinan China Shanghai Electric Power Corporation Ltd Shanghai China State Grid of China Technology College Jinan China

ISBN: (纸本)9781467381338

This paper presents a wide area control scheme using TCSC for damping inter-area oscillation. In general, TCSC are facilitated over long transmission lines to enhance the power transmission capability. As the inter-area oscillations are associated with heavy power transfer over long transmission corridors, the small signal/oscillatory stability can be improved if an additional damping control can be integrated into the control scheme of TCSC. The paper presents the classic and additional damping control scheme of TCSC. The typical two-area power system and control scheme that are built using `DIgSILENT PowerFactory', and the damping control is tested through the classic modal analysis and simulations in time domain.

关键词： Power capacitors Thyristors Damping Oscillators Economic indicators Power system stability system performance

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A new motion control method for omnidirectional intelligent wheelchair based on improved Fuzzy Support Vector Machine

A new motion control method for omnidirectional intelligent ...

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IEEE International Conference on Mechatronics and Automation

作者： Wentao Guo Songmin Jia Tao Xu Xiuzhi Li College of Electronic and Control Engineering Beijing University of Technology Beijing China Ministry of Education Engineering Research Center of Digital Community Beijing China Beijing Key Laboratory of Computational Intelligence and Intelligent System Beijing China

ISBN: (纸本)9781479970995

This paper proposed the FSVM (Fuzzy Support Vector Machine) based on affinity to achieve the intelligent wheelchair motion control. The gravity center, which can be computed by calculating the weights of four force sensors under the wheelchair seat, is the key factor to determine the intention of movement of the user. The improved fuzzy membership function of FSVM can reduce the effect of clustering gravity center caused by abnormal clustering gravity center data generated from malfunction. Comparing with the traditional SVM (Support Vector Machine), the improved FSVM algorithm has lower error rate. This paper further validates the practical feasibility and validity of the proposed control algorithm. The experiment results show that the proposed algorithm can improve the precision of omnidirectional intelligent wheelchair motion control.

关键词： Wheelchairs Gravity Support vector machines Clustering algorithms Training Force sensors Noise

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Human tracking method based on multi-template color-texture mean-shift algorithm

Human tracking method based on multi-template color-texture ...

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IEEE International Conference on Mechatronics and Automation

作者： Linfeng Wen Songmin Jia Lijia Wang College of Electronic and Control Engineering Beijing University of Technology Beijing China Ministry of Education Engineering Research Center of Digital Community Beijing China Beijing Key Laboratory of Computational Intelligence and Intelligent System Beijing China

ISBN: (纸本)9781479970995

Human tracking is a hot topic and a challenging task during the past few decades. This paper present a multi templates based strategy for human detecting and tracking with a mobile robot. This method first determines the coarse location by using adaptive template matching algorithm (ATM) based on head-shoulder. Then, a multi-templates based method is presented to locate the person precisely. Multi templates considering the pose changes are obtained to represent the person. For each template, the mean-shift is proceeded. Then, the accurate position is obtained by fusing the results of the Mean-shift from all the templates. After detecting the person, the templates are updated by considering the likelihood of the tracking results and the old templates. Finally, the method is evaluated on a mobile robot in complex environment. The experiment result shows that our method performs well when there are unclear disparity image and pose variations.

关键词： Image color analysis Histograms Target tracking Mathematical model Cameras Mobile robots Robot vision systems

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Coordinated optimization for controlling short circuit current and multi-infeed DC interaction

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Journal of Modern Power systems and Clean Energy 2014年第4期2卷 374-384页

作者： Dong YANG Kang ZHAO Yutian LIU State Grid Shandong Electric Power Research Institute Jinan 250002China Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong UniversityJinan 250061China

Due to increased penetration of renewable energies,DC links and other emerging technologies,power system operation and planning have to cope with various uncertainties and *** order to solve the problems of exceeding short circuit current and multi-infeed DC interaction,a coordinated optimization method is presented in this ***,a branch selection strategy is proposed by analyzing the sensitivity relationship between current limiting measures and the impedance ***,the impact of network structure changes on the multi-infeed DC system is *** the coordinated optimization model is established,which considers the cost and effect of current limiting measures,the tightness of network structure and the voltage support capability of AC system to multiple ***,the non-dominated sorting genetic algorithm II combining with the branch selection strategy,is used to find the Pareto optimal *** studies on a planning power system demonstrated the feasibility and speediness of this method.

关键词： Operation and planning Multiple DC infeed Short circuit current Sensitivity analysis Multi-objective optimization

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High-efficiency, broad-band and wide-angle optical absorption in ultra-thin organic photovoltaic devices

High-efficiency, broad-band and wide-angle optical absorptio...

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作者： Wang, Wenyan Hao, Yuying Cui, Yanxia Tian, Ximin Zhang, Ye Wang, Hua Shi, Fang Wei, Bin Huang, Wei Key Lab. of Advanced Transducers and Intelligent Control System Ministry of Education Taiyuan University of Technology Taiyuan 030024 China Key Laboratory of Interface Science and Engineering in Advanced Materials Taiyuan University of Technology Taiyuan 030024 China Key Laboratory of Advanced Display and System Applications Ministry of Education Shanghai University Yanchang Road 149 Shanghai 200072 China Nanjing 210046 China

Metal nanogratings as one of the promising architectures for effective light trapping in organic photovoltaics (OPVs) have been actively studied over the past decade. Here we designed a novel metal nanowall grating with ultra-small period and ultra-high aspect-ratio as the back electrode of the OPV device. Such grating results in the strong hot spot effect in-between the neighboring nanowalls and the localized surface plasmon effect at the corners of nanowalls. These combined effects make the integrated absorption efficiency of light over the wavelength range from 400 to 650 nm in the active layer for the proposed structure, with respect to the equivalent planar structure, increases by 102% at TM polarization and by 36.5% at the TM/TE hybrid polarization, respectively. Moreover, it is noted that the hot spot effect in the proposed structure is more effective for ultra-thin active layers, which is very favorable for the exciton dissociation and charge collection. Therefore such a nanowall grating is expected to improve the overall performance of OPV devices. © 2014 Optical Society of America.

关键词： Light absorption

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The Fitting Method of Wind Power Forecast Error under Power-time Dimension

The Fitting Method of Wind Power Forecast Error under Power-...

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International Conference on Electric Utility Deregulation and Restructuring and Power Technologies

作者： Zhaoqing Wang Chengfu Wang Jun Liang Xueli Wang Libin Yang Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Jinan China State Grid Shandong Electric Power Maintenance Company Jinan China State Grid Qinghai Electric Power institute Xining China

ISBN: (纸本)9781467371070

Randomness and volatility are the inherent attributes of wind power, and the present method for forecasting wind power is not accurate enough. However, the exact description of forecast error has obvious effect on optimized scheme of power flow calculation, unit commitment and operation in the power system with wind power. The wind forecast error is different under the power dimension and correlative under time dimension, so it can describe the actual wind power attributes more accurately on the basis of fitting the forecast error divided into different groups according to the power-time attributes. The parameters distribution like normal distribution can not describe the error in different bins accurately, but this paper proposed non-parameter kernel density estimation (NKDE) to fit the error data in various bins, which is also suitable for various forecast methods. If ignoring the characteristic of NKDE, it has poor fitting effect because of too many bins and too few data in some bins. This paper proposed a method to reduce the number of bins to improve the fitting effect and reduce calculation time. Results for this case show the proposed probability density function (pdf) is more close to the actual wind power error distribution.

关键词： error analysis fitting effect power-time dimension correlation

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