A dynamic state estimator for power system dynamic security assessment

A global modularized dynamic state estimator is formulated to provide the data which will be required for future dynamic security assessment and dynamic security enhancement applications. The dynamic state estimator is global because it is capable of estimating small and large dynamic fluctuations in voltage angle and frequency for an entire area. The dynamic state estimator is composed of the sum of the static state estimate, obtained by using present hardware and algorithms and a modularized dynamic state estimate based on a linearized classical transient stability model with a stochastic load model. This dynamic state estimate component is modularized to (1) eliminate the need to measure or model external system generation and (2) to permit a reduction in computation requirements for (a) updating the linearized power system dynamic model and (b) for computing the state estimate. The modularization, which is accomplished by decoupling the linearized dynamic model for each subregion by measuring the power injections on lines connecting the subregion to the rest of the power system, causes the dynamic state estimate to be locally referenced. A global referencing procedure is proposed and discussed. A linearized stochastic model for the Michigan Electric Coordinated System is developed to illustrate the procedures proposed for developing the stochastic load model and determining the constant gain approximation for the governor turbine energy system dynamics. A summary of results on the performance of the Kalman state estimator is presented.     

Application of fuzzy set theory to industrial pollution prevention: production system modeling and life cycle assessment

 This research describes a framework and case study application that merges fuzzy set methods, pollution prevention, and sustainable production concepts. There is a direct linkage between industrial pollution prevention, sustainability, and the solution of large-scale environmental problems. This linkage stems from the inherent desire for economic production, while at the same time protecting the environment from further degradation. The methodology combines systems analysis under imprecise conditions with a life cycle assessment method that is able to accept imprecise data. Analysis of systems under imprecise conditions is accomplished through analysis of process flow diagrams using fuzzy set techniques. Introduction of imprecision into life cycle assessment is accomplished by integration of fuzzy set approaches into a decision support system utilizing multiple criteria decision making. The framework is described and a case study application of an industrial parts cleaning system using an open top vapor degreaser is presented. Results of applying the method show that: (1) It is well suited for analysis of complex systems in which input data is sparse and expensive to collect. (2) The proposed framework includes a decision support system that is able to consider life cycle assessment concepts, and is able to reconcile differing opinions on available options for modification of production systems, thereby leading to more sustainable solutions. The authors would like to acknowledge the USEPA Region VII Pollution Prevention Division, and the Pollution Prevention Incentives for States program, for their support of this research. In addition, the authors would like to recognize the support of the University of Nebraska Water Resources Center and Center for Infrastructure Research. The authors would also like to thank Dan Crist and Yuezhang Wang for their assistance with fuzzy systems modeling.     

Implementation of an on-line dynamic security assessment program for the central China power system

The central China power system is currently implementing an on-line stability program. This is the second largest power system in China to implement such an on-line stability program, and probably one of the earliest practical implementations of a dynamic security assessment program (DSA) reported in the world. This paper presents the features of this program, its computational methods, the design considerations used, and some numerical results.     

A new tool for dynamic security assessment of power systems

This paper describes a new tool for dynamic security assessment of power systems, in which two technologies are combined: the EEAC method and time-domain simulations. Details of the structure and functionalities of the tool are discussed. The applications of the tool are illustrated with a realistic power-system model as an example. The results show that both fast computation speed and reliable performance are achieved.     

Power system model validation for power quality assessment applications using genetic algorithm

This paper presents an intelligent system for power quality assessment application. This system is used for power system model validation. A genetic algorithm (GA) based system for validating the power system model in capacitor switching studies has been developed. The problem formulation and the proposed solution are illustrated. The feasibility of the developed system for practical applications is demonstrated by evaluation studies.     

核电站系统安全评价指标体系研究

核电站系统的安全性是影响核电发展的一个重要因素.针对事故发生概率,安全系统的性能,事故造成的后果3个指标采用全局安全评价指数(GSI),并基于MATLAB模糊逻辑工具箱,提出安全评估框架和方法.对国内目前比较常用的压水反应堆(PWR)和新引进的AP1000两种反应堆类型进行评价,并对结果进行了比较,发现AP1000具有更高的安全性能,GSI最终评价结果能够非常直观的供核安全管理部门参考.     

A grid computing based approach for the power system dynamic security assessment

This paper addresses the problem of parallel dynamic security assessment applications from static homogeneous cluster environment to dynamic heterogeneous grid environment. Functional parallelism and data parallelism are supported by each of the message passing interface model and TCP/IP model. To consider the differences in heterogeneous computing resources and complexity of large-scale power system communities, a kernel-based multilevel algorithm is proposed for network partitioning. Since the bottleneck in distributed computation is low speed network communication, a bi-level latency exploitation technique is introduced for numerically solving system differential equations. The proposed grid-based implementation includes the core simulation engine, grid computing middleware, a Python interface and Python front-end utilities. Tests for a 39-bus network, a 4000-bus network and a 10,000-bus network are reported, and the results of these experiments demonstrate that the proposed scheme is able to execute the distributed simulations on computational grid infrastructure and provide efficient parallelism.     

Performance assessment of thermal power plant load control system based on covariance index

This paper proposes a novel method of performance assessment for load control system of thermal power unit. Load control system is the most important multivariable control system. It is necessary to monitor and evaluate the performance of it. The performance evaluation index system based on covariance is defined, and the performance evaluation rules are given. In MATLAB, the double input and double output object model of the load control system is established, and the dynamic characteristics of the load control system are analyzed under the BF and TF mode. The simulation data, which is based on the parameters retuning, is used as the “benchmark data”, and the simulation data of different controllers are collected as “monitoring data”. For most of the time, the thermal power plant is under the coordinated control mode, and the principle and strategy of the two coordinated control are analyzed, and the engineering realization scheme is given. Operation data in different time periods of two different thermal power plants was acquisition and preprocessing respectively. The principle of selecting “benchmark data” is the minimum of pressure parameter. Two data segments were selected as “benchmark data”, performance assessment and analysis was carried on the data from other time periods. The results show that the validity and reliability of the method based on the evaluation index. In short, the data of the simulation and the load control system of power plant are used to demonstrate the effectiveness of the method.     

A new information system in support of landscape assessment: PLAINS

Several business sectors have identified the potential benefits of a landscape/urban assessment based upon the objective appraisal of the interaction of the cultural and natural landscapes. This paper describes a recently approved project (PLAINS) funded by DGXII of the European Union under the Framework IV Environment and Climate Programme. The aim of this project is to identify the benefits of introducing satellite Earth Observation data into the landscape assessment process and to develop a decision support system that will provide for landscape/urban classification tuned to satisfy specific customer requirements. The system will also allow the exploration of impact assessment (‘what if’) scenarios. The project involves three different business sectors who have inherently similar requirements in landscape assessment. The ‘customer’ organisations involved in the project cover the sectors: regional planning authorities, Estate Agents and tourism. In all, there are 13 partners involved in the project from five countries (UK, Denmark, Germany, Italy, Poland). The initial development of the system will use test sites in the counties of Hereford and Worcester in the UK, with subsequent validation being carried out at sites in Italy (Province of Savona), Germany and Poland.     

Expert system support for environmental assessment of manufacturing products and facilities

The goal of environmentally conscious design for manufacturing is to select materials and processes that minimize environmental impact. This paper describes a general and uniform way to analyze the environmental impact of manufacturing based on the product decomposition, the materials used in the manufacturing processes, and the particular view of the environment. To accomplish this task, we developed a computer program, called EcoSys, that assists manufacturing engineers and environmental reviewers in assessing the environmental consequences of their manufacturing decisions.     

Stability in terms of two measures of dynamic system on time scales

By using a notion of upper quasi-monotone nondecreasing, this paper presents a new comparison principle which connects the solutions of two higher-dimensional dynamic systems on time scales. Then the stability criteria of a solution of a dynamic system in terms of two measures are obtained. Finally, two examples are provided to illustrate our results.     

Modelling the impacts of land system dynamics on human well-being: Using an agent-based approach to cope with data limitations in Koper,Slovenia

To cope with data limitations and to provide insight into the dynamics of LUCC for local stakeholders in the Municipality of Koper, Slovenia, we constructed an ABM (loosely defined) that integrates utility theory, logistic regression, and cellular automaton-like rules to represent the decision-making strategies of different agents. The model is used to evaluate the impact of LUCC on human well-being, as represented by the provision of highly productive agricultural soil, the extent of noise pollution, and quality-of-life measurements. Results for the Municipality of Koper show that, under a range of model assumptions, (1) high quality agricultural soils are disproportionately affected by urban growth, (2) aggregate resident quality of life increases non-linearly with a change in development density, (3) some drivers of residential settlement produce non-linear preference responses, and (4) clustering industrial development had a beneficial impact on human well-being. Additional novel contributions include the incorporation of noise pollution feedbacks and an approach to empirically inform agent preferences using a conjoint analysis of social survey data.     

Structural archetypes for coherency: A framework for comparing power system equivalents

The power system model is divided into a study system (SS) and an external group (EG). Three structural archetypes for coherency (SAC) are defined. Each SAC is a set of structural conditions on the power system which when satisfied cause the EG to remain coherent for disturbances confined to the SS. The validity of each SAC for both nonlinear and linear models of the power system is determined. The SAC provide a framework for comparing the three principal methods of determining reduced-order dynamic equivalents of power systems: coherency analysis, modal analysis and the singular perturbation decomposition (SPD) based on the separation of high and low frequency modes. It is shown that satisfaction of any of the three SAC causes the coherency and modal equivalents to be identical. Satisfaction of one particular SAC, termed strict synchronizing coherency, causes the coherency, modal and SPD equivalents to all be identical. The concept of a hierarchy of equivalents, based on the SAC is introduced and briefly discussed.     

Thermodynamic assessment of the La-Mg system

A thermodynamic modeling and optimization of the La-Mg system is carried out by means of the CALPHAD method taking into account the latest experimental results. The liquid, bcc-La, fcc-La, dhcp-La and hcp-Mg solutions are modeled as substitutional solutions (La, Mg) using the Redlich-Kister formalism. The LaMg, LaMg₂, La₅Mg₄₁, La₂Mg₁₇ and LaMg₁₂ phases are treated as stoichiometric compounds, and the non-stoichiometry of LaMg₃ is described as (La,Mg)_0.25Mg_0.75. The results are in good agreement with the set of experimental data which were carefully discussed and selected.     

A stochastic study of hidden failures in power system protection

Recent studies have shown that power systems protection mechanisms have played a major role in propagating disturbances. All of the last five major Western Systems Coordinating Council (WSCC) events (the North Ridge earthquake, December 14, 1994, July 2 and 3, 1996, and August 10, 1996), involved either false trips of line protection relays or generator protection equipment. Using an importance sampling based algorithm on the 179-bus WSCC equivalent system, we modeled the sequence of rare events involving generator trips and incorrect zone 3 relay operations. Due to possible loss of generation and load, frequencies were monitored for the necessary of load shedding. The algorithm uses the Newton–Raphson method for accuracy but reverts to DC load flow when the Newton–Raphson algorithm fails to converge within three iterations. The resulting sequence of rare events and its corresponding probability are used to detect weak links in the power system. This information can be beneficial not only in areas such as service and maintenance scheduling and in planning, but also in determining locations where an investment in improving the protection system is warranted.     

考试考核标准中的激励机制分析

合适的考试标准应该能够对学生和教师起着激励作用。针对考试考核标准的评价难题,将教师——学生组合作为研究对象,用激励灰度表示激励作用的程度;分析了考试考核标准下单个组合的收益,对激励灰度进行定性分析;然后分别从两个组合和组合群体的博弈过程中的收益,来分析各自的行动策略,得到考试评价标准激励程度的定量描述。     

含TEC复合材料热智能结构的仿真分析

功能单一的结构系统或温控系统已经不能满足航天器的要求,结构--温控功能一体化复合材料受到越来越多的重视.基于热电致冷器(TEC)的热特点,建立了含TEC片的复合材料热智能结构的热分析模型,以SINDA/G软件为仿真平台,研究了TEC片的安放位置、智能结构的热边界条件等因素对结构热分布的影响,还设计了热智能结构的温度控制系统,并利用SIMULINK软件进行了仿真.为热智能结构在计算机芯片的散热设计、红外隐身结构上的应用提供支持.     

Intelligent trainee behavior assessment system for medical training employing video analysis

This paper addresses the problem of assessing a trainee’s performance during a simulated delivery training by employing automatic analysis of a video camera signal. We aim at providing objective statistics reflecting the trainee’s behavior, so that the instructor is able to give valuable suggestions after the training. The basic idea is to analyze the moving and location parameters of the trainee, on which the behavior of the trainee can be judged and also compared. Our system consists of three major steps. In the first step, we label specific pixels with a given color, based on a Gaussian model. In the second step, the mean shift (MS) algorithm is employed to find the densest region of a color, where the center of that region indicates the center of a medical cap worn by a trainee. To accelerate the convergence of the MS algorithm, we propose to combine the distribution sampling and on-line mode updating based on the pyramid sampling technique. In the last step, we assume that the cap’s position represents the position of a trainee. Therefore, several statistics, such as the moving trajectory and the total movement of each trainee, can be calculated. These statistics associated with the domain knowledge, help us to determine trainees’ teamwork. Our system also enables an interactive way for instructors to choose the interested individual trainee, and then provides more results of him. Experimental evaluations using real delivery training videos demonstrate the effectiveness of the proposed work.¹     

Robust stability analysis of singular linear system with delay and parameter uncertainty

1Introduction It is well known that the existence of a delay in adynamical system may induce instability or poorperformances in various systems suchas electric,pneumatic,and hydraulic networks,chemical processes,longtransmission lines,etc.For a survey of time_delay systems,the reader can refer to a recent overview paper[1].Control of singular systems has been extensively studied inthe past years due to the fact that singular systems betterdescribe physical systems than regular ones.Agreat numb…