Discrete-time adaptive control applied to voltage regulation of induction generator based systems

Abstract

This paper deals with the development of an adaptive control system applied to voltage regulation of a standalone distributed power generation system, fed by self-excited induction generator. The generation system considers a four wire three-phase grid, composed by three phases plus neutral conductor, fed by three-phase three wires induction generator. The neutral conductor is created from the neutral point of star connection of excitation capacitors. The four-wire configuration allows the connection of three-phase loads in star or delta configuration, as well as single-phase loads. The voltage regulation is performed through a four-legs distribution static compensator (DSTATCOM) shunt connected to the AC bus. The adaptive controller proposed offers suitable voltage regulation in conditions of system's parameters variations such as, load connection and disconnection, and changes in induction generator's unmodeled parameters. The proposed generating system was simulated in MATLAB, where simulation results were obtained to show the good performance of the voltage regulation control system during the connection and disconnection of three-phase loads. Additionally, some preliminary experimental results are presented as well.

Considerations Regarding the Design of a Minimum Variance Control System for an Induction Generator

“…The following notations were used: w: set point, u: controller output (excitation voltage), y: controlled output (terminal voltage) and T m : mechanical torque provided by wind turbine through gearbox. Maintaining a constant voltage at the generator terminals is required in the context of connection with the power system [3,32,33].…”

“…The objective of the designed control strategy is to maintain constant the terminal voltage of the induction generator under the action of external disturbances, by controlling excitation voltage [2,3,32,33]. In fact, this operating regime is specific for a wind energy conversion system, when the voltage on the micro-grid power bus must be held constant, despite mechanical torque variations (due to wind speed changes) or electrical load or unload (by connecting or disconnecting electrical consumers at generator terminals).…”