MATLAB Implementation of Doubly-Fed Induction Generator (DFIG) with Control Strategies

The Doubly-Fed Induction Generator (DFIG) serves as the core component in wind power generation systems, characterized by its rotor connection to the grid through converters while the stator can operate either grid-connected or disconnected. When the stator is disconnected from the grid, the system enters a special operational state requiring control strategy adjustments to maintain stability. In MATLAB simulation modeling of DFIG, several key modules require primary focus: wind turbine characteristics, generator electromagnetic model, and rotor-side/grid-side converter controls. During stator disconnection, the rotor-side converter must independently handle excitation and power regulation functions, typically implemented using vector control strategies. The grid-side converter needs to switch to islanding mode to maintain DC bus voltage stability. Dynamic modeling requires special attention to the following issues: - When the stator circuit opens, transient rotor current surges may damage converters, necessitating current-limiting protection logic implementation; - Reduced system inertia after disconnection requires virtual inertia control compensation for frequency stability; - Power outer-loop controllers must be reconfigured to adapt to new operating conditions without stator power output. In MATLAB implementation, key functions would include: - Using Simulink's Power System Blockset for electromagnetic component modeling - Implementing dq-axis transformation in vector control algorithms - Designing PI controllers for power regulation and voltage stabilization - Creating state machines for mode switching between grid-connected and islanding operations Such models are commonly used to study grid fault ride-through capabilities or special applications like off-grid hydrogen production scenarios. The code typically involves mathematical modeling of machine equations, converter switching patterns, and protection system algorithms to simulate real-world operational challenges.