Nelson Martins

A comparison of classical, robust, and decentralized control designs for multiple power system stabilizers

Summary form only given as follows. Several control design techniques, namely, the classical phase compensation approach, the /spl mu/-synthesis, and a linear matrix inequality technique, are used to coordinate two power system stabilizers to stabilize a 5-machine equivalent of the South/Southeast Brazilian system. The open-loop system has an unstable interarea mode and cannot be stabilized using only one conventional power system stabilizer. Both centralized and decentralized controllers are considered. The different designs are compared and several interesting observations are provided.

Coordinated Stabilizer Tuning in Large Power Systems Considering Multiple Operating Conditions

This paper describes a new method for the coordinated gain tuning of PSSs, considering multiple operating points. The partial pole placement through the tuning of stabilizer gains is formulated as a nonlinear least squares problem, whose solution is obtained by the Newton method. The original problem is divided into various subproblems that are solved sequentially, in a way that is similar to continuation methods. The residues for the monitored poles, associated with the transfer functions of the stabilizer control loops (DeltaVPSS/DeltaVREF), are assembled into a rectangular matrix at every step of the continuation-like process. Results for the coordinated gain tuning of 36 stabilizers, considering 11 operating conditions, are described for a model of the Brazilian South-Southeast system.

The new CIGRE task force on coordinated voltage control in transmission networks

This short paper describes the preliminary scope and objectives of a new CIGRE task force, under the Advisory Group 02 of the Study Committee 38, on the coordinated voltage control in transmission networks. This report is presented at this panel session to promote a more effective CIGRE-IEEE/PES liaison in this area. CIGRE task forces have a life span of about two and a half years and should produce a Technical Brochure, to be published by CIGRE Central Offices.

A demonstration example of secondary voltage regulation: dynamic simulation and continuation power flow results

A demonstration example of secondary voltage regulation (SVR) is described. Results on a small test system are presented in a tutorial manner, highlighting the benefits gained with the use of a SVR scheme. Two simulation tools were used: a transient, mid-term stability program and a power flow continuation program. Full system data is provided, so that the results may be reproduced and expanded upon by others.

s-Domain approach to reduce harmonic voltage distortions using sensitivity analysis

This paper describes a Newton-Raphson method that shifts a set of electrical network poles and transfer function zeros to specify positions in the complex plane. These shifts aim at the improvement of the system harmonic voltage performance. The method is based on the calculations of poles, zeros and their sensitivities to changes in system parameters. These calculations are carried out in the s-domain using the nodal admittance matrix Y(s) and its derivative with respect to the complex frequency s. A comparison is made between the proposed method and a recent one based on descriptor system approach. As is shown in the paper, the proposed method combines the advantages of the conventional admittance matrix method and modal analysis.

Filter design using a Newton-Raphson method based on eigenvalue sensitivity

A Newton-Raphson method was proposed previously to accurately shift the electrical network poles and zeros to more suitable locations in the complex plane to improve the harmonic voltage performance of a system. The poles and/or zeros shifts were carried out by appropriate changes in the capacitor and/or reactor banks. Based on this concept, this paper presents a Newton-Raphson method to accomplish the required shifts by changes in harmonic filter parameters. In this way, a single tuning filter, designed by this method, is shown to solve the harmonic problem of the bus where it is connected as well as another harmonic problem at a different system bus. Achieving these two objectives with just one single tuning filter may be economically attractive.

A Newton-Raphson method based on eigenvalue sensitivities to improve harmonic voltage performance

This paper describes a Newton-Raphson method that accurately shifts a set of electrical network poles and transfer function zeros to more suitable locations in the complex plane to improve the harmonic voltage performance of a system. The descriptor system approach is used for the computer modeling of electrical networks of any topology and their subsequent modal analysis. The pole and/or zero shifts are carried out by appropriate changes in the system elements (e.g. capacitor and/or reactor banks). Eigenvalue sensitivity coefficients are used to help determine those element changes that are the most cost-effective and also to compute de Jacobian elements for the Newton method. These changes may be carried out without impacting the system operating point. Results are presented for a realistic system model in order to show the potential applications of the method.