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With the increase in the monitoring of operational data at very high rates in high voltage substations and the ability to time synchronize these data with global positioning systems, there is a growing need for transmitting this data for monitoring, operation, protection, and control needs. The sets of data that need to be transferred and the speed at which they need to be transferred depend on the application--for example, slow for postevent analysis, near real rime for monitoring and as close to real rime as possible for control or protection. In this paper, we describe GridStat, a novel middleware framework we have developed to provide flexible, robust, and secure data communications for the power grid's operations. Test results demonstrate that such a flexible framework can also guarantee latency that is suitable for fast wide-area protection and control. Index Terms--Computer control of power systems, distributed control, energy-management systems, power system measurements, power system monitoring, power system protection, quality of service (QoS), supervisory control and data-access (SCADA) systems, wide-area control.

This paper deveiops a systematic procedure of designing a centralized damping control system for power grid interarea oscillations putting emphasis on the signal selection and control system structure assignment. Geometric measures of controllability/observability are used to select the most effective stabilizing signals and control locations. Line power flows and currents are found to be the most effective input signals. The synthesis of the controller is defined as a problem of mixed [H.sub.2]/H[infinity] output-feedback control with regional pole placement and is resolved by the linear matrix inequality (LMI) approach. A tuning process and nonlinear simulations are then used to modify the controller parameters to ensure the performance and robustness of the controller designed with linear techniques. The design process is tested on the New England 39-bus ten-machine system. Index Terms--Damping controller, interarea oscillations, robust control, wide-area control, wide-area measurements.

In this paper, we present the design of a localized competitive market for reactive power ancillary services at the level of individual voltage-control areas. The concept of electrical distance has been used to identify the different voltage-control areas within a power system. The proposed reactive power market is settled on uniform price auction, using a modified optimal power-flow model. Uniform prices for various components of reactive power service are obtained for each voltage-control area. In the study cases described in the paper, we examine whether such a localized reactive power market is more desirable than a common system-wide reactive power market. Index Terms--Ancillary services, deregulation, market design, reactive power, voltage-control areas.

The problem of defining and classifying power system stability has been addressed by several previous CIGRE and IEEE Task Force reports. These earlier efforts, however, do not completely reflect current industry needs, experiences and understanding. In particular, the definitions are not precise and the classifications do not encompass all practical instability scenarios. This report developed by a Task Force, set up jointly by the CIGRE Study Committee 38 and the IEEE Power System Dynamic Performance Committee, addresses the issue of stability definition and classification in power systems from a fundamental viewpoint and closely examines the practical ramifications. The report aims to define power system stability more precisely, provide a systematic basis for its classification, and discuss linkages to related issues such as power system reliability and security. Index Terms--Frequency stability, Lyapunov stability, oscillatory stability, power system stability, small-signal stability, terms and definitions, transient stability, voltage stability.

In this paper, the objectives and detailed analysis of the multistage distribution expansion are presented. The problem is modeled as a directed graph minimum edge cost network flow problem. This new formulation details a multistage framework within a single mathematical program while addressing several deficiencies of previous approaches. The accuracy of a single step approximation of the objective function, without using the conventional linearization techniques, is discussed. Each of the constraints is introduced in terms of industry standard practices. Detailed numerical results for practical study cases are provided in a separate paper. Index Terms--Power system planning, distribution expansion, multistage planning, mixed integer mathematical programming.

In this paper, the numerical analysis of a multistage formulation of the distribution expansion problem developed is presented. The approximate objective function is employed without sacrificing optimality. A complete nonlinear mathematical programming optimization is employed to identify the global optimum. The algorithm is applied here to two practical test cases. Details of the input data and configuration of test systems as well as the solutions are listed and discussed. Computational considerations are addressed. Index Terms--Distribution expansion planning, mixed integer mathematical programming, multistage planning.

With deregulation of the power generation sector, the necessity for an enhanced and open communication infrastructure to support an increasing variety of ancillary services is apparent. A duplex and distributed communication system seems to be the most suitable solution to meet and ensure good quality of these services. Parameters needed and additional limits introduced by this new communication topology must be investigated and defined. This paper focuses on the communication network requirements for a third party load frequency control service. Data communication models are proposed based on queuing theory. Simulation is performed to model the effects of certain types of signal delays ancillary service, on this Index Terms--G/G/1 queues, load frequency control, network delays, queueing theory.

This paper resulted from the research aimed at introducing modeling and simulation as a major methodological approach for enhancing power engineering education. The reasons for such an approach are explained first. Different options and uses of the modeling and simulation tools are discussed next. Several implementations of the teaching examples are outlined. The paper ends with the conclusions reached based on the study. Index Terms--Load-flow analysis, modeling, power engineering education, power system transients, protection, simulation, stability, state estimation.

Fast contingency screening is expected to be an integral part of any practical on-line dynamic security analysis (DSA). Ranking of contingencies requires the use of severity indices, and for DSA such an index must be a measure of stability. From experience in static security analysis, it is well known that some indices work better than others for particular power systems and that combinations of indices usually work better than a single index. For DSA, which is still in its infancy, severity indices are more complex and very few have been tested for screening. In this paper, several indices are proposed for contingency screening in online DSA. These indices are based on the concepts of coherency, transient energy conversion between kinetic energy and potential energy, and three dot products of system variables. Test results on realistic power systems show the promise of these indices in contingency screening. Keywords: Dynamic Security Analysis, Transient Stability, Contingency Screening, Severity Index.

At present, the computational requirement for dynamic security assessment (DSA) is a hurdle for a comprehensive on-line DSA to be implemented in Energy Management Systems. In addition to faster time domain solutions, novel approaches and techniques are being developed for contingency screening and remedial actions. This paper describes one such development in the area of contingency screening which can be seen as an extension of techniques developed over the years for static security analysis. Some new concepts and methods are suggested for both contingency ranking and contingency classification (stable/unstable). Results from realistic test systems illustrate the capabilities and performance of the new approach. Key words: Severity Index, Contingency Screening, Dynamic Security Analysis, Artificial Neural Network

Parallel processing to obtain time domain simulation of power system dynamic behavior has been studied for over a decade. In this paper, a parallel across space implementation of a Waveform Relaxation (WR) based algorithm is presented. The algorithm can take full advantage of the inherent properties of power systems, such as coherency grouping and localized fault response, thus significantly speeding up the simulations. In the proposed implementation, a system is broken up into several subsystems based on its coherency, and then each processor is devoted to the computation of the waveform of each subsystem. This is the first time the WR algorithm has been implemented on a parallel machine (Sequent Symmetry S81) and tested on large power systems. The numerical results show very promising performance compared with the commonly used Very Dishonest Newton algorithm, with overall speedups of up to 27 obtained for a 2500-bus system using 20 processors. Keywords Waveform relaxation, parallel processing, dynamic simulation, network partitioning, multiple stepsizes.