# Performance Validation of Control Algorithm Considering Independent Generator Torque Control in PCS
## 1 Introduction
Although no quantitative comparison was presented, the simulation results indicated load reduction, as evidenced by the analysis of the auto power spectrum of the tower accelerations in both fore-aft and side-to-side directions [20]. [PERSON] et al. designed and applied individual pitch control to reduce the loads on wind turbines. The simulation results confirmed a significant reduction in the 1P component of the blade bending moment [22]. The generator torque and blade pitch control commands for wind turbines are calculated through algorithms uploaded to the PLC, which acts as the brain of the wind turbine [23; 24; 25]. Typically, the generator speed is input from sensors such as encoders, and the torque and blade pitch commands are calculated according to the control objectives. These commands are then sent to the Power Conversion System (PCS) or the blade pitch actuator controller. In some wind turbines, the torque command is not generated by the PLC but directly by the PCS, which carries out torque control [26]. This independent torque control within the PCS estimates the generator speed using the generator's voltage signals and applies the corresponding current command to the generator based on the required generator reaction torque [27]. In other words, this control system uses a current signal schedule based on the voltage signals during the process of calculating the generator torque command. The PCS torque control independently generates control commands and sends them to the wind turbine, separate from the algorithm operating within the PLC. Meanwhile, the PLC calculates the blade pitch commands for pitch control, independently of the PCS torque control. In systems where independent PCS torque control is applied, the control algorithms used in conventional systems, where the generator reaction torque and blade pitch angle commands are calculated by the PLC, cannot be directly applied. These algorithms must be appropriately modified to suit the changed operating environment. Therefore, in this study, a power control algorithm was designed for wind turbines equipped with independent PCS torque control, which had not been considered in previous research, and its performance was experimentally validated. Additionally, to compare the performance of the proposed algorithm with that of a conventional wind turbine, where both the torque and pitch control are executed by the PLC, a control algorithm that performs both torque and pitch control in the PLC was designed [27; 28]. To ensure a smooth transition between the control strategies of Region II and Region III during power control, the Set Point Smoother (SPS) method, proposed in the previous literature, was slightly modified [29], and a control transition logic considering only pitch control was designed. The performance of the proposed control algorithm was validated through dynamic simulations, as well as wind tunnel experiments using a scaled wind turbine model under conditions that included turbulent wind and sensor noise. The contributions of this study can be summarized as follows:  
* A power control algorithm was designed for medium-sized wind turbines with independent PCS torque control by modifying conventional wind turbine control algorithms. * To improve the performance of the control transition logic applied in previous research, an SPS considering only pitch control was implemented. * The operational performance of power control using PLC-based torque and pitch control, PCS-based torque control, and PLC-based pitch control was compared in a dynamic simulation environment. * Experimental validation was conducted using a scaled wind turbine model under turbulent conditions and sensor noise in a wind tunnel to simulate real-world scenarios.