In renewable systems, there may be conditions that can be either network error or power transmission line and environmental conditions such as when the wind speed is unbalanced and the wind turbine is connected to the grid. In this case, the control system is not damaged and will remain stable in the power transmission system. Voltage stability studies on an independent wind turbine at fault time and after fixing the error is one of the topics that can strengthen the future of independent collections. At the time of the fault, the network current increases dramatically, resulting in a higher voltage drop. Hence the talk of fast voltage recovery during error and after fixing the error and protection of rotor and grid side converters against the fault current and also protection against rising DC voltage (which sharply increases during error) is highly regarded. So, several improvements have been made to the construction of a doubly-fed induction generator (DFIG) turbine such as:
a) error detection system,
b) DC link protection,
c) crow bar circuit,
d) block of the rotor and stator side converters,
e) injecting reactive power during error,
f) nonlinear control design for turbine blades,
g) tuning and harmonization of controllers used to keep up the power quality and to stabilize the system output voltage in the power grid.
First, the dynamic models of a wind turbine, gearbox, and DFIG are presented. Then the controllers are modeled. The results of the simulation have been validated in MATLAB/Simulink.