Maximum power extraction and reliable power transfer from super-large-WECS to grid network using finite-time sliding mode-based current and voltage control scheme

Attaining optimal mechanical and electrical power extraction and reliable power transmission from multi-megawatt power-rated wind energy conversion systems (WECS) to grid networks is paramount. Therefore, a robust control system is pivotal in realizing these advantages. Thus, this study is dedicated to enhancing the reliability of super-large WECS by optimizing energy extraction efficiency. The initial focus involves introducing a grid-connected WECS utilizing synchronous generators with a 3-level neutral point clamping back-to-back converter topology. Following this, a novel rotor speed controller is designed to regulate the generator speed based on the finite-time sliding mode control (SMC) approach. The controller design is achieved based on SMC theory, featuring a novel sliding surface and utilizing the exponential reaching law. Subsequently, the dq-axis voltage controller of the machine-side converter is devised using a similar procedure. A comprehensive stability analysis is then conducted to validate the finite-time error convergence of the designed controllers. Finally, the efficiency and applicability of the proposed controllers are verified through simulations involving a 5kW permanent magnet vernier generator (PMVG)-based WECS and a 20MW permanent magnet synchronous generator-based WECS. In addition, empirical validation is obtained from a grid-connected 5 kW PMVG-based wind turbine in an experimental setup.