A DSE-Based SMC Method of Sensorless DFIG Wind Turbines Connected to Power Grids for Energy Extraction and Power Quality Enhancement

Extracting the maximum possible kinetic energy from the ambient environment and enhancing the output power quality are two main concerning issues on the topic of integrating renewable energy resources with power grids. For this purpose, we propose a dynamic state estimation (DSE)-based sliding mode control (SMC) strategy to achieve such control purposes for doubly fed induction generator (DFIG) wind turbines connected to multi-machine power grids. The newly devised method leverages cutting-edge smart-grid technology for the design of dynamic state estimator, and the acquired states of sensorless DFIG systems are then utilized in the construction of the SMC scheme. A dechattering method is also proposed to alleviate unnecessary switchings that intrinsically exist in the original SMC scheme. Compared with the conventional control method, when operating under high wind speeds, the newly designed SMC strategy of DFIGs is capable of producing a faster response time, a higher mechanical energy extraction percentage, and a better power quality. Owing to the modern smart-grid technology and simplicity in implementing the SMC strategy, the proposed control method infers its potential of practical applications in industrial vision.