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Underspeed needle control of two Peiton turbine hydro units operating in a small power system has caused many incidents of partial system blackouts. Among the causes are con-servative governor designs with regard to small signal stability limits, nonminimum phase power characteristics, and long tunnel-penstock traveling wave effects. A needle control model is developed from "water to wires" and validated for hydro-turbine dy-namics using turbine test data. Model parameters are tuned using a trajectory sensitivity method. In the governor design proposed here the needle regulation gains are distributed into the power and frequency governor loops with a multi-timescale approach. Elements of speed loop gain scheduling and a new inner-loop pressure stabilization circuit are devised to improve the frequency regulation and to damp the traveling wave effects. Sim-ulation studies show the improvements of the proposed control designs. [ABSTRACT FROM AUTHOR]

Dynamic regulation models for voltage-sourced converter (VSC) based flexible ac transmission system (FACTS) controllers are described in this paper. The dynamic models can then be used to analyze these FACTS controller's capability to improve the capability of a power transfer path. The contributions of this paper include showing that the benefits of FACTS controllers are proportional to the MVA ratings and the benefits of multiple FACTS controllers are cumulative. Furthermore, the coupling of dc buses allowing active power circulation between multiple VSC FACTS controllers may offer additional improvement in transfer capability. [ABSTRACT FROM AUTHOR]

Flexible ac Transmission Systems (FACTS) play an important role in improving the transfer capability and stability of a power system. In the application of voltage-sourced converter (VSC)-based FACTS controllers, it is important to study how a VSC impacts the flows in a power system. In this paper, we investigate this flow control problem using two sensitivity approaches, one using an injected voltage source formulation and the other an equivalent impedance formulation. The applications of sensitivity analysis for line active power redispatch and for new series VSC siting in a 1673-bus system are presented. [ABSTRACT FROM AUTHOR]

Due to their ability to provide reactive power support and control active power flow, voltage-sourced-converter (VSC)-based flexible ac transmission system controllers can be used to improve the power transfer capability of congested transmission lines. A converter-based controller structure has the inherent feature to be used to provide shunt or series compensations. This inherent feature is utilized in the convertible static compensator installed at the New York Power Authority's Marcy substation, which can operate in 11 configurations of shunt and series compensations. Moreover, each configuration can be operated in different control modes. The paper presents a novel approach to model converter-based transmission controllers for load-flow calculations. The paper focuses on modeling converter-based controllers when two or more VSCs are coupled to a dc link (e.g., unified power-flow controller (UPFC), interline power-flow controller, and a generalized unified power-flow controller). This approach also allows efficient implementation of various VSC operating limits, where one or more VSCs are loaded to their rated capacity. A computer program incorporating this approach is developed to illustrate the maximum dispatchability of UPFC and IPFC in a large power system. [ABSTRACT FROM AUTHOR]

This paper develops a measurement-based method for estimating a two-machine reduced model to represent the interarea dynamics of a radial, multimachine power system. The method uses synchronized bus voltage phasor measurements at two buses and the line current on the power transfer path. The innovation is the application of the interarea oscillation components in the voltage variables resulting from disturbances for extrapolating system impedances and inertias beyond the measured buses. Expressions for the amplitudes of the bus voltage and bus frequency oscillations as functions of the location on the transmission path are derived from a small-signal perturbation approach. The reduced model provides approximate response to disturbances on the transfer path and offers an alternative to model reduction techniques based on detailed system models and data. [ABSTRACT FROM AUTHOR]

Many large interconnected power systems such as the U.S. eastern interconnection and the U.S. western power system are characterized by many power transfer paths or interfaces with high loading. Disruptions of these transfer paths frequently lead to increased loading on neighboring transfer paths, which themselves will become less secure and could cause further disruptions. State estimators have limited performance under large system disruptions, because of low sampling rates and potentially poor solution quality due to topology errors. Furthermore, disruptions in external power systems cannot be readily seen by control room operators because most state estimators only use reduced models for external systems. A system of well-placed phasor measurement units (PMUs) that provide voltage and current magnitude and phase at a high sampling rate can provide useful system dynamic security information. In this paper we apply energy function analysis using phasor data to monitor the dynamic status of power transfer paths. The ideas will be illustrated using actual data captured by several PMUs in the U.S. western power system. [ABSTRACT FROM AUTHOR]

System reliability is an integral part of a properly designed deregulated electricity market, even though wholesale energy prices are its most visible piece. This paper discusses the resources, collectively known as the ancillary, services, in a power system for maintaining reliability. It then discusses an integrated approach in systematically determining and securing the needed ancillary services and system configuration across multiple time spans, culminating in the cooptimization of energy and ancillary services for security-constrained generator unit commitment in the day-ahead market and security-constrained economic dispatch of the generators in real-time operation. The paper also provides a summary of the ancillary services market in several U.S. power markets and proposes several technical issues for further discussion and research. [ABSTRACT FROM AUTHOR]

For a system with a unified power-flow controller (UPFC), maximum power transfer capability is often achieved when the UPFC is operated at its rated capacity and conventional voltage and line-flow setpoint regulation is no longer possible. This paper uses injected voltage sources to directly model a UPFC and impose the rating limits in a Newton-Raphson load-flow algorithm. A dispatch strategy is proposed for a UPFC operating., at rated capacity in which the power circulation between the shunt and series converters is used as the parameter to optimize the power transfer. Voltage-stability curves for two test systems are shown to illustrate the effectiveness of this proposed strategy. [ABSTRACT FROM AUTHOR]

The use of power system stabilizers (PSS) to damp power system swing mode oscillations is of practical importance. The design of PSS is taught in graduate level courses on power system dynamics aid control, and has been the topic of numerous M.S. and Ph.D. theses. This paper discusses the experience in assigning PSS projects in an undergraduate control design course to provide students with a challenging design problem using three different techniques and to expose them to power system engineering. The details of the PSS design projects using root-locus, frequency-domain and state-space methods are provides. [ABSTRACT FROM AUTHOR]

For a power industry undergoing deregulation, the growing number of power marketers and independent power generators increases the variability of power flow patterns in an interconnected power system, thereby making the prediction of critical operating conditions and limits more demanding. Consequently, transmission system operators need new tools to understand the effects of disturbances. Among these needs are tools to classify and identify disturbances as they occur on the power system. In this paper, power system disturbance data from the Northfield substation dynamic recording device in the US New England power system are analyzed and their features extracted. Then a classification method is used to identify the disturbance. Events with multiple disturbances are also addressed. A MATLAB-based software, called ‘Event Analyzer’, has been developed for the disturbance identification. [Copyright &y& Elsevier]

Describes the results of a study which evaluated the performance of three identification methods for the study of low frequency electromechanical oscillations. Brief overview of the identification methods; Criteria for comparing the identification methods; Description of the test systems.

Presents information on an integrated approach used for designing damping controllers for large power systems. Indices of design proposed for evaluating feedback signals; Overview of the exact multi-modal decomposition; Computation of design indices.

Investigates the general case of time-optional control of series capacitors which requires multiple switchings Uses of time-optional control of switchable series; How the time-optional design was developed; Discussion on two suboptimal control schemes.

Proposes a time-optimal series capacitor control to damp interarea modes in multi-machine systems. Time-optimal control of interarea modes; Test of the system; Design of switching control; Conclusions.

Describes the application of a reduction method to power systems to obtain simplified models that facilitate the design of damping controllers. Balanced realization; Singular values; Reduction algorithm; Transfer functions; System parallel connection; Reduction method without balancing.

Provides information on a study that presents the results of applying the EPRI Dynamic Equivalencing Program to a large-scale electric power system test case of the New York Power Tool. Background of the study; Computational procedures; Conclusions.