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An algorithm for the detection and frequency estimation of periodic forced oscillations in power systems is proposed. The method operates by comparing the periodogram of synchrophasor measurements to a detection threshold. This threshold is established by deriving a general expression for the distribution of the periodogram and is related to the algorithm's probabilities of false alarm and detection...
Power system small-signal electromechanical dynamic properties are often described using linear system concepts. The underlying hypothesis is that small motions of the system can be described by a set of ordinary differential equations. Modal analysis of these governing equations provides considerable insight into the stability properties of the system. Over the past two decades, many signal processing...
In power systems forced oscillations occur, and identification of these oscillations is important for the proper operation of the system. Two of the parameters of interest in analyzing and addressing forced oscillations are the starting and ending points. To obtain estimates of these parameters, this paper proposes a time-localization algorithm based on the geometric analysis of the sample cross-correlation...
Real-time monitoring of power-system oscillations is a concern in the operation and control of synchronous power systems. A simple and powerful approach is to use an RMS energy filter. As defined in this paper, an RMS energy filter estimates the total RMS energy of a signal in a defined frequency band. This approach has been implemented in the operation control center at the Bonneville Power Administration...
Prony analysis has been used to estimate oscillation modes from ringdown responses in a power grid. When applying Prony analysis, several factors must be considered to estimate the modes accurately. In this paper, a general prediction model is proposed for the Prony analysis. The influence of decimation factors, model orders, and linear solvers on estimation accuracy is studied using the Monte Carlo...
Accurate and near real-time estimates of electromechanical modes are of great importance since the modal damping is a key indicator of the stability of the power system. If the estimates of the electromechanical modes are to be useful, knowing the variability in the estimates is critically important. This paper presents a method of directly estimating the variance of each mode estimate in addition...
Prony analysis has been applied to estimate inter-area oscillation modes using phasor measurement unit (PMU) measurements. To suppress noise and signal offset effects, a high-order Prony model usually is used to over-fit the data. As such, some trivial modes are intentionally added to improve the estimation accuracy of the dominant modes. Therefore, to reduce the rate of false alarms, it is important...
Small signal stability problems are one of the major threats to grid stability and reliability. Prony analysis has been successfully applied on ringdown data to monitor electromechanical modes of a power system using phasor measurement unit (PMU) data. To facilitate an on-line application of mode estimation, this paper develops a recursive algorithm for implementing Prony analysis and propose an oscillation...
This paper investigates the design of effective input signals for low-level probing of power systems. In 2005, 2006, and 2008 the Western Electricity Coordinating Council (WECC) conducted four large-scale system-wide tests of the western interconnected power system where probing signals were injected by modulating the control signal at the Celilo end of the Pacific DC intertie. A major objective of...
Summary form only given. This paper proposes a regularized robust recursive least squares (R3LS) method for on-line estimation of power-system electromechanical modes based on synchronized phasor measurement unit (PMU) data. The proposed method utilizes an autoregressive moving average exogenous (ARMAX) model to account for typical measurement data, which includes low-level pseudo-random probing,...
Monitoring of intrapleural pressure (IPP) is used for evaluation of lung function in a number of pathophysiological conditions. We describe a telemetric method of non-invasive monitoring of the IPP in conscious animals intermittently or continuously for a prolonged period of time.After IACUC approval, six mongrel dogs were used for the study. After sedation, each dog was intubated and anesthetized...
A time-limited pseudo-random signal is an important component in perturbation signals during a system identification procedure. In this paper, a finite-time duration pseudo-random waveform with desired continuous spectral features is generated using an extended time-frequency domain swapping algorithm. Impulse responses of finite impulse response (FIR) filters are used as initial waveforms. Through...
Precision-cut tissue slices have proven to be a useful in vitro system for biotransformation and toxicity studies. Since tissue slices can be readily prepared from a variety of tissues and species, they can easily be used for interspecies investigations and comparisons. Furthermore, slices can be readily prepared from human tissue, thus comparisons (extrapolation) can be made between laboratory...
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