Zhelinskyi M. Vector control system of induction generator with robustness properties to parametric perturbations.

The thesis is devoted to research and development of new vector control algorithms for autonomous induction generators (IG) with improved static and dynamic characteristics. Based on the analysis of existing control methods and types of existing electric power generation systems, it is shown that: a) the classic PI-vector control algorithm has no rigorous theoretical substantiation; b) the stability of essentially nonlinear system is not proved; and c) it is sensitive to coordinate and parameter perturbations. The theoretical analysis and investigation of the stability properties and characteristics of the saturated IG vector control systems in the standard configuration with linear PI current and voltage controllers (which take into account the saturation of IG magnetic system) are performed. Classic algorithm provides local asymptotic stability of DC-link voltage and rotor flux regulation under limited load current and decomposition of the voltage and q-axis current subsystems, based on the two-time scale separation. A new feedback linearizing control of DC-link voltage is developed. It is synthesized on the base of the balance equation of electromechanical conversion and for the first time provides the linear dynamics of the voltage regulation subsystem regardless of changes in angular speed, module of rotor flux vector and load current. A method for the synthesis of direct vector control of the IG flux subsystem based on a new reduced order flux observer has been developed. The systems with developed algorithms were studied in simulation. It is shown that static and dynamic characteristics degrade when using standard configuration with linear PI current and voltage controllers under conditions of active rotor resistance variation. Under high active rotor resistance increase, this algorithm does not provide stable operation unlike developed robust algorithm. The robust algorithm with direct field orientation has been developed, which provides robustness to variation of rotor active resistance. An adaptive observer, which takes into account the IG saturation, has been synthesized and investigated in autonomous mode and as part of an adaptive control system. It provides higher accuracy level of flux tracking by applying the combination of robust vector control algorithm (to rotor active resistance variations) and the adaptive observer, providing exponential estimation of rotor active resistance. The adaptive control system does not require information about the initial values of the rotor active resistance. Intensive experimental comparison study of proposed controllers and indirect vector control with linear PI voltage regulators were conducted on the created experimental installations with IGs of 2.2 kW and 5.5 kW rated power. Experimental results coincide with the simulation and shows that improved dynamic quality indicators of DC-link voltage control are obtained as well as higher efficiency is achieved. The results of the work were implemented in the educational process at the National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute" in teaching the subjects "Electromechanical systems in environmentally friendly technologies", "Robust and adaptive control in electromechanical systems". Keywords: induction generator, vector control, robustness, adaptation, observer.