Power system loading margin is a fundamental measure of a system's proximity to voltage collapse. Linear and quadratic estimates to the variation of the loading margin with respect to any power system parameter or control are derived. Tests with a 118-bus system indicate that the estimates accurately predict the quantitative effect on the loading margin of altering the system loading, reactive power support, wheeling, load model parameters, line susceptance and generator dispatch. The accuracy of the estimates over a useful range and the ease of obtaining the linear estimate suggest that this method will be of practical value in avoiding power system voltage collapse.

/pdf/sensitivity-of-the-loading-margin-to-voltage-collapse-with-3u8e1smi2k.pdf

Sensitivity of the loading margin to voltage collapse with respect to arbitrary parameters

A power system may be subject to (rotor) angle, frequency or voltage instability. Voltage instability takes on the form of a dramatic drop of transmission system voltages, which may lead to system disruption. During the past two decades it has become a major threat for the operation of many systems and, in the prevailing open access environment, it is a factor leading to limit power transfer. The objective of this paper is to describe voltage instability phenomena, to enumerate preventive and curative countermeasures, and to present in a unified and coherent way various computer analysis methods used or proposed.

/pdf/voltage-instability-phenomena-countermeasures-and-analysis-477bn8wpdr.pdf

Voltage instability: phenomena, countermeasures, and analysis methods

In this paper the design of power system stabilizers for small-signal stability using phasor measurements is considered. An approach based on optimal control with structural constraints is proposed to design a two-level control structure. Time delays are included in the design. The method is combined with order reduction to ensure faster convergence of the design algorithm and to facilitate the choice of the weighting matrices for damping interarea modes. The control scheme is discussed and modal analysis and time-domain simulations of two Brazilian equivalent systems are performed to assess the control performance. The robustness to loss of communication links, topological changes, and variations of time delay is evaluated.

Wide-Area Measurements-Based Two-Level Control Design Considering Signal Transmission Delay

This paper provides a comprehensive list of books, reports, workshops and technical papers related to voltage stability and security

Bibliography on voltage stability

This paper describes the results of a study to evaluate the performance of three identification methods for the study of low frequency electromechanical oscillations. The three identification methods considered are: the Steiglitz-McBride algorithm; the eigensystem realization algorithm; and the Prony method. The identification methods are used to identify low order linear systems of power systems modeled in standard transient stability programs. This is accomplished by processing the system response to a simple probing pulse. The frequency domain characteristics of several identified systems are compared using three power systems with lightly damped electromechanical modes.

Performance comparison of three identification methods for the analysis of electromechanical oscillations

A new program, EXSTAB (extended time-scale stability) has been developed for representing a wide variety of power system performance problems, from transient stability through long-term dynamics and voltage instability. The capability of the program includes multiple execution modes and automatic step size selection to address conflicting goals of accuracy and efficiency. The modeling includes a broad range of apparatus to provide the needed time-scale representation (four orders of magnitude). Models for automatic generation control, plant characteristics and control, voltage and reactive power control, static and dynamic loads, and protective relaying for apparatus and system connections are provided. Technologies were developed to perform analysis of voltage stability and prediction of peak power transfer to avoid voltage collapse. >

Multiple time-scale power system dynamic simulation

The maximum continuous power output of a combined-cycle power plant depends on the system frequency and the ambient temperature. The temperature control of a gas turbine limits the exhaust temperature by reducing the fuel flow as the airflow decreases with the shaft speed. In this paper, a simple model of a combined-cycle power plant is derived from a detailed design model for an example plant. The model is suitable for long-term simulation of power system dynamic performance involving abnormal frequency conditions.

Modeling combined-cycle power plant for simulation of frequency excursions

A system for on-line dynamic screening of contingencies comprising postulated disturbances which an electric power system may experience, the system comprising a dynamic contingency screening program for evaluating a plurality of contingencies with a plurality of contingency classifiers based on the method of finding the controlling unstable equilibrium point of the power system known as the boundary of stability region based controlling unstable equilibrium point method by sequentially applying the contingencies to a network islanding problem classifier, SEP problem classifier, a large stability regions classifier, an exist point problem classifier, a ray adjustment problem classifier, an energy function problem classifier, a CUEP convergence problem classifier, and a controlling UEP (unstable equilibrium point) classifier to form a first group of stable contingencies and a second group of unstable or undecided contingencies, and a time-domain simulation program for determining which of the second group of contingencies are unstable

Method and system for on-line dynamical screening of electric power system

The effects of the laminated paper layer direction on the conductivity and the dc breakdown strength in oil-impregnated paper were experimentally clarified. It was confirmed that not only oil and paper discharges through the laminated paper layers, but also paper discharges along them triggered total flashover in oil and oil-impregnated paper composite insulation. Analyses verified the usefulness of the dc flashover voltage calculation method, based on a non-linear directional field calculations and the lowest flashover voltage estimations between paper discharges along the laminated paper layers and oil and paper discharges through them.

Atsushi Kurita

Papers

Multiple time-scale power system dynamic simulation

Modeling combined-cycle power plant for simulation of frequency excursions

Method and system for on-line dynamical screening of electric power system

DC Flashover Voltage Characeteristics and Their Calculation Method for Oil-Immersed Insulation Systems in HVDC Transformers

Improvements of numerical stability of electromagnetic transient simulation by use of phase-domain synchronous machine models