Stable equivalent models with minimum phase transfer functions in the dynamic aggregation of voltage regulators

• Published in: Electric power systems research Vol. 81; no. 2; pp. 599 - 607
• Main Author: Pires de Souza, Eduardo J.S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2011; Elsevier
• Subjects: Applied sciences; Coherent generators; Dynamic aggregation; Dynamic equivalents; Electrical engineering. Electrical power engineering; Electrical machines; Exact sciences and technology; Miscellaneous; Squared-variable transformation; Transient stability; Voltage regulators; England; United Kingdom; Great Britain; Europe; Dynamic equivalents; Dynamic aggregation; Transient stability; Squared-variable transformation; Coherent generators; Voltage regulators; Synchronous machine; Unconstrained optimization; Optimization method; Electric machine; Coherence; Equivalent circuit; Salient pole machine; Transfer function; Time constant; Comparative study; Excitation systems
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2010.10.019

The dynamic aggregation is a step of the calculation of coherency-based dynamic equivalents. If the dynamic aggregation of voltage regulators is solved as an unconstrained optimization problem, negative time constants may appear in the solution, which characterize unstable equivalent models and/or nonminimum phase equivalent transfer functions. The squared-variable transformation is considered to solve this problem. The solutions of the dynamic aggregation problem of voltage regulator models obtained with both the original formulation and the squared-variable transformation are compared. A criterion is also proposed to select the best equivalent voltage regulator model for each coherent group. The New England system, including salient-pole synchronous machines with subtransient effects and excitation system models, is considered in the studies.