Ph.D Thesis

Ph.D StudentSpitsa Vitaly
SubjectRobust Approach to Power System Voltage Stability
DepartmentDepartment of Electrical and Computer Engineering
Supervisors PROFESSOR EMERITUS Ezra Zeheb
PROFESSOR EMERITUS Abraham Alexandrovitz
Full Thesis textFull thesis text - English Version


In the present work voltage stability of a power system is studied. The main factors affecting this type of stability are described. Among them load characteristics play a key role. Traditional power system analysis does not account for large uncertainties which are inevitably present in these characteristics due to a constantly changing power demand. In the research work it is shown how by adopting robust control theory one may find a complete set of uncertain load parameters for which voltage stability is preserved. The proposed techniques are based on a particular testing function, a root clustering analysis and on a zero set concept. Voltage stability can be improved by a proper reactive power support. In the second part of the work, this problem is solved using a static synchronous compensator (STATCOM). Its best location in the power system is determined using a modal analysis. Then a robust state-feedback controller for STATCOM is designed. The design method combines ideas from a theory of linear matrix inequalities and zero set calculations. Finally, design centering was performed to obtain controller gains providing maximally possible safety margins.