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During 2005 and 2006, the Western Electricity Coordinating Council (WECC) performed three major tests of western system dynamics. These tests used a Wide-Area Measurement System (WAMS) based primarily on phasor measurement units (PMUs) to determine response to events including the insertion of the 1400-MW Chief Joseph braking resistor, probing signals, and ambient events. Test security was reinforced through real-time analysis of wide-area effects, and high-quality data provided dynamic profiles for interarea modes across the entire western interconnection. The tests established that low-level optimized pseudo-random [+ or -]4-20-MW probing with the Pacific DC Intertie (PDCI) roughly doubles the apparent noise that is natural to the power system, providing sharp dynamic information with negligible interference to system operations. Such probing is an effective alternative to use of the 1400-MW Chief Joseph dynamic brake, and it is under consideration as a standard means for assessing dynamic security. Index Terms--Performance monitoring, phasor measurements, system testing, Wide-Area Measurement System (WAMS).

The frequency and damping of electromechanical modes offer considerable insight into the dynamic stability properties of a power system. The performance properties of three mode-estimation block-processing algorithms from the perspective of near real-time automated stability assessment are demonstrated and examined. The algorithms are: the extended modified Yule Walker (YW); extended modified Yule Walker with Spectral analysis (YWS); and sub-space system identification (N4SID). The YW and N4SID have been introduced in previous publications while the YWS is introduced here. Issues addressed include: stability assessment requirements; automated subset selecting identified modes; using algorithms in an automated format; data assumptions and quality; and expected algorithm estimation performance. Index Terms--Electromechanical dynamics, mode estimation, phasor measurement units (PMUs), power system stability, situational awareness, software certification.

In this paper, the authors use the Numerical algorithm for Subspace State Space System IDentification (N4SID) to extract dynamic parameters from phasor measurements collected on the western North American Power Grid. The data were obtained during tests on June 7, 2000, and they represent wide area response to several kinds of probing signals, including low-level pseudo-random noise (LLPRN) and single-mode square wave (SMSW) injected at the Celilo terminal of the Pacific HVDC Intertie (PDCI). An identified model is validated using a cross validation method. Also, the obtained electromechanical modes are compared with the results from Prony analysis of a ringdown and with signal analysis of ambient data measured under similar operating conditions. The consistent results show that methods in this class can be highly effective, even when the probing signal is small. Index Terms--Estimation, phasor measurements, power system modeling, power system monitoring, Numerical algorithm for Subspace State Space System IDentification (N4SID), system identification, Wide Area Measurement System (WAMS).

Field experience is reported for a thyristor controlled series capacitor (TCSC) recently commissioned at BPA's Slatt substation. Subsynchronous resonance tests show that TCSC interactions with shaft dynamics of PGE's Boardman steam generator are well understood and are effectively avoided by normal TCSC valve firing logic. Modulation tests, performed with the Boardman plant off line, show that the TCSC can be a powerful and responsive actuator for swing damping. Security considerations did not permit lightly damped operation of the controlled plant. Close analysis indicates that the TCSC damping contribution, though small, was measurable. The best estimate is that damping for the McNary mode is 7.33% and 8.55%, for the TCSC damper loop open and closed respectively. TCSC testing and monitoring is facilitated by an advanced interactive measurement network representing BPA's approach to the information requirements of major control systems. Keywords - TCSC, FACTS, network resonance, feedback control, power system monitoring.

Recently, a 500-kV thyristor controlled series capacitor (TCSC) was installed in the Bonneville Power Administration system in the northwestern United States. Extensive field testing has included modulation experiments to determine the effectof the TCSC on low-frequency oscillations.This paper discusses modulation procedures, analysis methods, and results for estimating the damping effectiveness of the TCSC. Modulation methods include driving the TCSC with step and random noise, and analysis techniques include time (Prony analysis) and frequency-domain identification. Results indicate that: 1) the TCSC can have significant impact on system dynamics; and 2) under a very small feedback gain, the TCSC provides measurable added damping.

As a part of an EPRI-sponsored development on advanced power modulation control system for HVDC lines, dynamic system monitors (DSM) were installed at the dc terminals of the Square Butte system. The monitors were used to validate the computer models used for the controller design and will be used to validate the performance of the controllers after installation. The paper describes the use of Prony analysis and Fourier techniques to analyze system disturbances and to validate the computer models. As described in the paper, excellent results have been achieved at least for parts of the system for some well defined disturbances.

In this paper, the authors use the Numerical algorithm for Subspace State Space System IDentification (N4SID) to extract dynamic parameters from phasor measurements collected on the western North American Power Grid. The data were obtained during tests on June 7, 2000, and they represent wide area response to several kinds of probing signals, including low-level pseudo-random noise (LLPRN) and single-mode square wave (SMSW) injected at the Celilo terminal of the Pacific HVDC Intertie (PDCI). An identified model is validated using a cross validation method. Also, the obtained electromechanical modes are compared with the results from Prony analysis of a ringdown and with signal analysis of ambient data measured under similar operating conditions. The consistent results show that methods in this class can be highly effective, even when the probing signal is small. [ABSTRACT FROM AUTHOR]