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Abstract Power electronics–based converters for photovoltaic (PV) systems are susceptible to overcurrents; it is important to design their controllers to reduce the transient current for all viable operating conditions. To design a current controller and find the maximum transient current via simulation‐based techniques, the exact values of the system parameters, initial states, and inputs are required. However, they are not precisely known in practice, some system parameters such as inductances may change over time, and output power and load are variable. The uncertainty in the parameter (filter inductance) and input of the system (injected power) should be considered in the analysis of a PV system controllers as it can degrade their performance, which are designed for the system nominal parameters. This paper employs reachability analysis for a grid‐connected PV system to (1) find the maximum transient current, (2) devise an improved PI current controller and (3) compare the maximum transient current in PI‐ and internal model control (IMC)‐based controllers with uncertain‐but‐bounded input power and inductance error. Simulation and experimental studies showcase the results. 

Integration of wind energy resources into the grid creates several challenges for power system dynamics. More specifically, Type-3 wind turbines are susceptible to subsynchronous control interactions (SSCIs) when they become radially connected to a series-compensated transmission line. SSCIs can cause disruptions in power generation and can result in significant damage to wind farm (WF) components and equipment. This paper proposes an approach to mitigate SSCIs using an online frequency scan, with optimized phase angles of voltage harmonic injection to maintain steady-state operation, to modify the controllers or the operating conditions of the wind turbine. The proposed strategy is simulated in PSCAD/EMTDC software on the IEEE second benchmark model for subsynchronous resonance. Simulation results demonstrate the effectiveness of this strategy by ensuring oscillations do not grow. 

In recent years, penetration of renewable energy resources into the power grid has increased significantly. Wind, as a renewable, clean, and abundantly available source of energy, has an important share in the energy mix. However, increasing the penetration of wind power in the power grid can adversely affect the power quality and introduce new operational challenges. This paper discusses issues related to the integration of wind farms in the power system, such as maximum power point tracking, fault ride-through capabilities, interarea and subsynchronous oscillations, and voltage flicker, and provides a review of the existing control strategies to address these issues in Types I, II, III, and IV wind turbines. This paper also identifies challenges and opportunities ahead. 

High integration of renewable energy resources, such as wind turbines, to the power grid decreases the power system inertia. To improve the frequency response of a low-inertia system, virtual inertia approach can be used. This letter proposes a control method to decrease the frequency transients and restore frequency to its nominal value. A wind turbine usually works based on maximum power point tracking (MPPT) curves to achieve the maximum power. In this letter, the proposed controller uses a non-MPPT method to leave power for frequency regulation during transients. Moreover, it uses a washout filter-based method to remove the steady-state error in the frequency. Simulation results in the PSCAD environment validate the improved performance of the proposed method during load changes by comparing it with the MPPT and non-MPPT methods.