Browsing by Author "Shabestari, Parisa M."
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- Frequency Response Improvement of PMSG Wind Turbines Using a Washout FilterShabestari, Parisa M.; Mehrizi-Sani, Ali (MDPI, 2020-09-14)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.
- Transient behaviour verification and controller tuning for an uncertain grid-connected photovoltaic system using reachability analysisShabestari, Parisa M.; Mehrizi-Sani, Ali (2021-05-25)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.