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International Conference on Critical Infrastructures, CRIS

作者： Gang Li Gengyin Li Wei Yue Ming Zhou K L Lo Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China Department of Electronic and Electrical Engineering University of Strathclyde Glasgow UK

Distributed generation (DG) technology has drawn increasing attention for its tremendous benefits to customers, utilities and the environment. Furthermore, microturbine based power generation has become the most promising DG for its excellent record of improving system stability and economy. In this paper we develop a complete mathematic model, which includes the microturbine, a permanent magnet synchronous generator (PMSG), a three-phase bridge AC to DC rectifier, a boost converter and a DC to AC inverter. The simulated microturbine generation system (MTGS) model is a single shaft type with control systems and capable of regulating its output power in grid-connected mode. Also, the design and modeling of a MTGS which is suitable for isolated operation are explained with the ability of electronic controls that maintains the output voltage at their prescribed levels. Different load conditions are applied to the MTGS for evaluation of the validity and practicability of the model. Simulation studies have been carried out in PSCAD/EMTDC under different load conditions. Simulation results testify that the MTGS developed from this model can produce predictable results with these control methods.

关键词： Fuels Mathematical model Load modeling Inverters Power generation Voltage control Torque

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An improved grey model for forecasting spot and long term electricity price

An improved grey model for forecasting spot and long term el...

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International Conference on Power system Technology (POWERCON)

作者： Zheng Yanan Gengyin Li Ming Zhou Shan Lin K L Lo Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China Department of Electronic and Electrical Engineering University of Strathclyde Glasgow UK

With the deepening reform to power industries, power systems are going to gradually open the demand side and the power consumers have to face the changes of their role in the market, and make a preliminary long-term forecasting for the electricity prices. In order to consider the relations between the spot market and the long-term contract market, this paper builds a multi-electricity price grey model to comprehensive forecast the prices of the 2 markets; further researches the structure of the background value, and improves the multi-electricity price grey model; and introduces the residual error, the related grade, the mean variance ratio and the little probability of error as test indexes. The test results show that the multi-electricity price grey forecasting model and its improved model have better accuracy, and the improved model has stronger adaptability and extends the application range.

关键词： Forecasting Contracts Predictive models Electricity Accuracy Fitting Indexes

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The generating mechanism and optimal control of power quality in micro-grids

The generating mechanism and optimal control of power qualit...

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International Conference on Power system Technology (POWERCON)

作者： Xi Li Zhongqiu Wang Gengyin Li Ming Zhou K L Lo Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China Department of Electronic and Electrical Engineering University of Strathclyde Glasgow UK

As an important component of distribution network, micro-grid is the necessarily development trend for future. Micro-grid has greatly improved the random problems of distributed generation (DG). However, DGs, the power electronic equipments inevitably bring about power quality problems, especially voltage flicker and harmonics. This paper tries to study the operating regulations of micro-grid in order to find out the generating mechanism and propagation characteristic of power quality problems. Taking the photovoltaic (PV) system for an example, the micro-grid simulation model has been set up. The experiments show that an appropriate control strategy coordinating every part can improve the power quality of micro-grid greatly. This paper finds out the factors affecting power quality and their harm degrees, explaining the reasons of power quality problems. Coordinating every unit, this paper set up an optimal control strategy and proper parameter settings, trying to improve power quality of micro-grid to the largest extent.

关键词： Power quality Biological system modeling Inverters Harmonic analysis Power grids Integrated circuit modeling Voltage fluctuations

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Energy storage control for the Photovoltaic generation system in a micro-grid

Energy storage control for the Photovoltaic generation syste...

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International Conference on Critical Infrastructures, CRIS

作者： Zhongqiu Wang Xi Li Gengyin Li Ming Zhou K L Lo Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China Department of Electronic and Electrical Engineering University of Strathclyde Glasgow UK

Distributed generation (DG) that uses renewable energy sources has an unstable output and this can negatively affect existing electric power systems. In order to reduce above impact, we need to develop an energy control system to control the output through individual DG installed in a micro-grid. First, this paper designs a grid-connected Photovoltaic (PV) system and introduces the operation principle of the various parts as well with the control strategy of the power flow. The design of energy storage is of great significance as the output power of PV cells array is greatly affected by the light intensity and the temperature change. Then, it uses the battery as the energy storage device and designs the charge-discharge control strategy according to the characteristics of the battery. Finally it verifies the feasibility of the energy storage control strategy through the simulation models which is built based on the PSCAD/EMTDC platform.

关键词： Batteries Discharges Voltage control Arrays Solar power generation

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Fundamental modeling of vehicle power network system using VHDL-AMS

Fundamental modeling of vehicle power network system using V...

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International Symposium on Power electronics, Electrical Drives, automation and Motion, SPEEDAM

作者： Shingo Ueno Kimitoshi Tsuji Takashi Abe Tsuyoshi Higuchi Koichi Shigematsu Department of Electrical and Electronic Engineering Nagasaki University Nagasaki Japan Advanced Vehicle Control System Eng. Dev. Toyota Motor Corporation Susono Shizuoka Japan CYBERNET SYSTEMS Company Limited Nagoya Japan

The vehicle system is a multi-domain system that requires many branches of science and engineering. Therefore the development of the vehicle system requires the use of design methodologies that utilize simulations, which have grown increasingly sophisticated in recent years. This paper describes how VHDL-AMS was used to model the powertrain, alternator and battery system that are the basic elements of the vehicle power network system, and examines the simulation results with the aim of realizing a system simulation whose scope covers the entire vehicle.

关键词： Power system modeling Mechanical power transmission Alternators Battery powered vehicles Vehicle driving Circuit simulation Engines Automotive engineering Power system simulation Carbon dioxide

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A method of automatic integration test case generation from UML-based scenario

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WSEAS Transactions on Information Science and Applications 2010年第4期7卷 598-607页

作者： Ogata, Shinpei Matsuura, Saeko Course of Functional Control Systems Graduate School of Engineering Shibaura Institute of Technology 307 Fukasaku Minuma-ku Saitama-City Saitama 337-8570 Japan Department of Electronic Information Systems College of System Engineering and Science Shibaura Institute of Technology 307 Fukasaku Minuma-ku Saitama-City Saitama 337-8570 Japan

One key to success for high quality enterprise information systems development is to validate the customers' requirements sufficiently at the early stage. Scenarios are an effective means to an end because they make it possible to represent various situations of system usage. Most scenarios are defined by using a natural language or such a formal language as Unified Modeling Language (UML) and describe normal, alternative, and exceptional service flows from the point of view of system usage. As a result, scenarios make it easy for the customers to confirm their requirements intuitively because of the concreteness. On the other hand, based on the V-model, which is well-known software development process and denotes the correspondence of requirement analysis stage to integration test stage, it is desirable that the testers should test the system by using the test cases derived from the validated scenarios. We have proposed a UML-based requirements analysis (RA) model with automatic prototype system generation for enterprise Web application development. This paper proposes a way to efficiently create reliable test cases from the scenarios that have been validated by the customers using the prototype system which was generated by the RA model.

关键词： Integration testing

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Evaluation of a use-case-driven requirements analysis tool employing web UI prototype generation

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WSEAS Transactions on Information Science and Applications 2010年第2期7卷 273-282页

It has been widely acknowledged that ambiguous or incomplete customer requirements are a major reason for the failure of software development projects. A key example of this is the inconsistency between implementation image and specifications provided in the early stages of software development. To address this, we propose a method for automatic generation of user interface prototypes for developing Web-based business applications, based on the requirements specifications defined in the Unified Modeling Language (UML). In this study, we compare the proposed method with traditional use case modeling to evaluate the effectiveness of the proposed method.

关键词： Unified Modeling Language

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Active leader tracking control of multi-agent systems with quantized measurements

Active leader tracking control of multi-agent systems with q...

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Chinese control Conference (CCC)

作者： Jiangping Hu Yiguang Hong Gang Feng School of Automation Engineering University of Electronic Science and Technology of China Chengdu 610054 China Key Lab of Systems and Control Institute of Systems Science Chinese Academy of Sciences Beijing 100190 China Department of MEEM City University of Hong Kong Kowloon Hong Kong

This paper discusses tracking control problem with a discrete-time multi-agent system with active leader and quantized communication constraints. For the active leader in a general linear form, we give a distributed design for each discrete-time agent in the leader tracking control problem and analyze the tracking convergence with the help of Riccati equation and common Lyapunov function when the communication channel is perfect. Then a stochastic quantization strategy is applied to model the information transmission in the agent coordination and the corresponding solution is also given, even if the interconnection topology is switching.

关键词： Lead Multiagent systems Symmetric matrices Convergence Stochastic processes Switches Topology

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Comprehensive evaluation method of power quality based on variable weight and set pair analysis

Comprehensive evaluation method of power quality based on va...

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IEEE General Meeting Power& Energy Society

作者： Guodong Li Gengyin Li Xiang Li Ming Zhou Xiaodong Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China Department of Electrical Engineering Tsinghua University Beijing China School of Electrical and Electronic Engineering North China Electric Power University Beijing China

In this paper, variable weight theory and set pair analysis (SPA) theory are applied to comprehensive evaluation of power quality. Among existing comprehensive evaluation methods of power quality, the problems about index uncertainty and imbalance case are less considered. The application of variable weight SPA, for ensuring identical discrepancy contrary (IDC) of unsure system, effectively reduces the complication of assessment process. Variable weight SPA uses the hybrid model of variable weight to modify power quality indices vector, and the final weights of indices could be determined. Then it takes advantage of new weight vector to compute the relativity coefficient of power quality assessment points. Finally the levels of power quality assessment points are assessed by their relativity coefficient. The results of the simulation show that the method used to carry out comprehensive evaluation of power quality is simple, and the classification is detailed. This method could effectively decrease the impact on index uncertainty to assessment results.

关键词： Power quality Indexes Uncertainty Voltage fluctuations Electrical engineering Entropy

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Monte Carlo simulation based assessment of available transfer capability in AC-DC hybrid systems

Monte Carlo simulation based assessment of available transfe...

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International Conference on Critical Infrastructures, CRIS

作者： Junqiang Wei Gengyin Li Ming Zhou K L Lo Department of Mathematics North China Electric Power University Beijing China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China Department of Electronic and Electrical Engineering University of Strathclyde Glasgow UK

Available transfer capability (ATC) is defined as a measure of the system's capability for transfers of power for further commercial activity, over and above already committed uses. In practical power markets, ATC can provide important information for transmission customers, system operators and power marketers. The assessment of ATC should be carried out to assure the secure, economic, stable and reliable operation of power systems. Most of the existing ATC calculation are mainly focused on AC power system and based on deterministic techniques. As high voltage direct current (HVDC) power distribution systems have been extensively used in modem transmission network, less work has been done on evaluation of ATC in AC-DC hybrid power system. This paper is dealing with the evaluation of ATC for the integration of HVDC link with an AC power system. The mathematical model of ATC for AC-DC hybrid power system is proposed. Due to the stochastic nature of power system behaviors, it is important to assess ATC from a statistical and risk analysis point of view. Considering the dynamics, time-varying and uncertainties of hybrid power systems, several statistical indices are presented to evaluate ATC and they are calculated based on Monte Carlo simulation. States of system operation can be simulated, and the algorithm based on MATPOWER (A MATLAB™ Power system Simulation Package) is developed in the environment of MATLAB 7.5. Case study with a modified IEEE 30-bus AC-DC hybrid power system is used to verify the presented approach. Sequential solution method is employed to deal with the AC-DC power flow. Five-number summary and other statistical indices of ATC are calculated. The results show that the proposed method is effective and practical. The research achievements are undergoing to transfer to the application in other hybrid power systems with different control style, and some new problems are suggested at the end of paper.

关键词： Load flow Monte Carlo methods Power system dynamics HVDC transmission Hybrid power systems Mathematical model

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