Examinando por Autor "Yang, Wandi"

Mostrando 1 - 2 de 2
  • No hay miniatura disponible
    Ítem
    Gradient Descent Optimization Based Parameter Identification for FCS-MPC Control of LCL-Type Grid Connected Converter
    (Institute of Electrical and Electronics Engineers Inc., 2022-03-01) Long, Bo; Zhu, Zilin; Yang, Wandi; Chong, Kil; Rodriguez, Jose; Guerrero, Josep M.
    Aging and temperature changes in the passive components of an LCL-filter grid connected converter system (GCCs) may lead to parameter uncertainties, which can in turn influence its modeling accuracy for finite-control-set model predictive control (FCS-MPC). The presence of model errors will change the resonance point and deteriorate the power quality of the grid current, in turn degrading the active damping performance. In this situation, there is a serious possibility that the GCCs may malfunction and automatically disconnect from the grid, causing great challenges to the system stability. To solve this problem, first, prediction error analysis in FCS-MPC due to the model parameter errors is presented. Second, to achieve high accuracy and fast filter parameter estimation in utility, an adaptive online parameter identification method based on gradient descent optimization (GDO) has been proposed. Finally, to further reduce the searching time needed by the optimal iteration step, a variable iteration step searching method based on the root-mean-square-prop (RMSprop) GDO method is proposed. Experimental studies of an LCL-GCCs prototype in the laboratory have been conducted to validate the effectiveness of the proposed method.
  • Miniatura
    Ítem
    Power-frequency admittance model of multi-VSGs grid-connected system considering power coupling
    (Elsevier Ltd, 2024-01) Long, Bo; Yang, Wandi; Zhu, Shihan; Tianxu, Cao; Guerrero, Josep M.; Rodríguez, José; Zang, Xian
    The high penetration of renewable energy decreases the inertia of power systems. The virtual synchronous generator (VSG) control technology has good inertia compensation effect and has attracted considerable attention because of the similar external characteristics of synchronous generators. However, the power and frequency oscillation of multi-VSG grid-connected systems seriously threatens the stability of power system. Existing multi-VSG power frequency admittance (PFA) models ignore the power coupling caused by the large line impedance ratio in medium- and low-voltage microgrids, and the accuracy of these models needs improvement. Thus, this study aims to establish a multi-VSG grid-connected PFA model considering power coupling. The influence of power coupling on model accuracy is analyzed, and the impacts of line impedance and reactive loop coefficient on the power-frequency response characteristics are investigated. Simulation results verify that the proposed model has higher accuracy over existing models. © 2023 The Author(s)