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Stabilizer design for dynamic stability control of multimachine power systems Li, Qinghua

Abstract

The development of new techniques for stabilizer design has been receiving considerable attention of power system industry. In this thesis, several new stabilizer design techniques are developed for the improvement of dynamic stability of multimachine power systems. Three kinds of dynamic stability problems are dealt with: the low—frequency oscillations, the stability of power systems with wide—range changing operating conditions and the multi—mode torsional oscillations of a two—machine system. Therefore, different stabilizer design techniques are developed. First, mathematical models are developed for dynamic studies and stabilizer design of multimachine power systems. Methods are also developed to select the number and the locations of stabilizers for the entire power system. A new pole-placement technique is developed for a decentralized Power System Stabilizer (PSS) design to control low—frequency oscillations. The computation is economic. The technique is applied to the stabilizer designs of a three—machine system and a nine— machine system. Simulation results show that PSSs thus designed are very effective to control low—frequency oscillations. A direct self—tuning regulator (STR) design method is developed for power systems with wide-range changing operating conditions. The indirect STR of Clarke based on the Generalized Predictive Control (GPC) method is improved so that the initial step control parameters are directly estimated and that the subsequent control parameters are recursively computed. The techniques developed are applied to the STR design of a nine—machine system. Comprehensive tests show that the STRs designed can effectively stabilize the power system with wide—range changing operating conditions while well— designed PSSs fail to do so. Finally, another pole—placement technique is developed for the excitation control of multi—mode torsional oscillations of a power system due to the subsynchronous resonance of a capacitor—compensated transmission line. This is a decentralized linear feedback design. The new technique is applied to the stabilizer design of the Second Benchmark Model of IEEE, System 2. Test results show that stabilizers designed can effectively control the torsional oscillations of the system over a wide—range of capacitor compensations.

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