Complex Torque Coefficient Analysis of Multi-Device Power Systems

[摘要] This thesis is concerned with the analysis of torsional interaction phenomena which may occur in modern power systems containing high bandwidth power control devices. In particular, it examines the suitability of Complex Torque Coefficient Analysis in providing a powerful yet visually appealing tool for the study of the underlying mechanisms and which overcomes the lack of physical understanding inherent in other methods of analysis. In its most basic form, the Complex Torque coefficient represents the transfer function between a change in electromagnetic torque and the change in rotor angle which produced it. By recognising that the additional current flowing in the stator windings as a result of this action is composed of a supersynchronous component and a subsynchronous component, the influence of the external network on the behaviour of the machine may be represented by the complex impedance matrix which describes the response of the network at the super- and subsynchronous frequencies. The first part of the thesis reviews the techniques currently used in the general study of dynamic stability in power systems and the background and mathematical description of the Complex Torque Coefficient is introduced. It is shown that this method of analysis is easily applied to the phenomenon of Subsynchronous Resonance due to the use of series compensation capacitors on long transmission lines. The second part deals with the extension of the method to the multi-machine problem and to the study of interactions between synchronous machines and power flow controllers including an assessment of the risk posed to turbine shaft fatigue due to noncharacteristic harmonics. The mechanism underlying the Subsynchronous Torsional Intelacdoa phenomena now known to exist between synthronous- miachines and Static Var compensators is demonstrated. The method of analysis highlights the significant advantages that the use of Thyristor Controlled Series Compensation devices may have over passive compensation schemes.

[发布机构] University:University of Glasgow

[关键词] Electrical engineering