# Performance Validation of Control Algorithm Considering Independent Generator Torque Control in PCS
## 3 Simulation Validation  
The algorithm for power control and control switching, considering the independent torque control of the PCS in the target wind turbine, has been completed using Matlab/Simulink (version 2023a) and finalized in DLL format. The external controller in DLL format was integrated with the dynamic simulation program Bladed for control performance verification. Bladed provides numerical modeling capabilities for all components of the target wind turbine, including the blades, tower, aerodynamics, drivetrain, etc. It is a program that offers dynamic simulation functionality to users through integration with an external controller via a DLL format. The dynamic simulation was conducted using the 100 kW model selected as the target wind turbine. The simulation conditions included average wind speeds of 10 m/s and 12 m/s, with a turbulence intensity normal turbulence model Class C applied, and the simulations were conducted over 600 s in each of these conditions. Figure 5: Overall schematic of the proposed power control algorithm. Figure 6: Structure of the pitch PI control algorithm with SPS. Figure 7 shows the simulation results for the rotor speed, pitch angle, generator torque, and generator power values considering the reference power control applied in previous studies and the power control designed in this study with the PCS independent generator torque control. Figure 7a presents the simulation results under an average wind speed condition of 10 m/s, while Figure 7b shows the results under an average wind speed of 12 m/s. The simulation results indicate that, with the consideration of the PCS torque control, the generator torque value is predominantly affected by the rotor speed. Upon examining Figure 7, it can be seen that, when the independent PCS torque control is applied, the sharp drop in the generator torque observed in the reference power control is alleviated. However, in the Region III area, while the reference power control maintains the generator torque at a constant rated value, the PCS torque control exhibits a variable value depending on the rotor speed. This indicates that increasing the standard deviation of the generator torque and generator power may relatively deteriorate the operational performance compared to the reference power control. When applying the PCS torque control, variable generator torque occurs in Region III because the torque command in the PCS is calculated based on the generator speed. In contrast, the reference power control methods utilize the PLC to provide a fixed torque command, whereas the PCS torque control inherently cannot maintain a constant torque. This introduces the additional challenge of being unable to utilize the reference power control methods. Despite these limitations, the PCS torque control has been adopted as the control method for the target wind turbine system to reduce manufacturing and development costs. The performance of the control algorithm, considering this specific scenario, has been validated through simulations. Tables 3 and 4 present the quantitative values of the rotor speed and generator power based on the simulation results. For the rotor speed, a tendency toward a relative decrease in standard deviation values compared to the reference power control was observed, with reductions of approximately 2.67% under 10 m/s conditions and about 24.55% under  
Figure 7: Comparison of the performance between the reference power control and power control considering the independent generator torque control. (**a**) Simulation results under an average wind speed of 10 m/s; (**b**) Simulation results under an average wind speed of 12 m/s. 12 m/s conditions. In the case of the generator power, the impact of the reduced standard deviation of rotor speed led to a decrease of 4.46% under 10 m/s conditions and about 13.99% under 12 m/s conditions.