access icon free Direct voltage control of stand-alone DFIG under asymmetric loads based on non-singular terminal sliding mode control and improved extended state observer

© The Institution of Engineering and Technology
Received 26/06/2018, Accepted 26/02/2019, Revised 06/02/2019, Published 27/02/2019

This study investigates direct voltage control of stand-alone doubly-fed induction generator (DFIG) system subject to asymmetric loads. An improved voltage regulator is designed based on non-singular terminal sliding mode control and an improved extended state observer (ESO). Due to the salient features of the improved ESO, the rotor current transducer is not required and the sinusoidal fluctuation in the sliding surface caused by asymmetric loads is eliminated. As a result, satisfactory balanced stator voltage can be generated under asymmetric loads. The proposed method is characterised by the rapid dynamic response and the elimination of sequence decomposition operations. Finally, the proposed method is applied to a 6 kW DFIG-based hardware system under various loads and varying speed conditions. Both simulation and experiment results are given to validate the effectiveness and robustness of the proposed method for stand-alone DFIG system.

Inspec keywords: asynchronous generators; variable structure systems; stators; power generation control; observers; rotors; voltage control; dynamic response

Other keywords: nonsingular terminal sliding mode control; improved voltage regulator; direct voltage control; asymmetric loads; improved ESO; balanced stator voltage; varying speed conditions; stand-alone DFIG system; induction generator system; improved extended state observer; DFIG-based hardware system; sliding surface

Subjects: Multivariable control systems; Voltage control; Simulation, modelling and identification; Asynchronous machines; Control of electric power systems; Control system analysis and synthesis methods

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