Examinando por Autor "Guerrero, Josep M."

Mostrando 1 - 5 de 5
  • No hay miniatura disponible
    Ítem
    Adaptive fuzzy fractional-order sliding-mode control of LCL-interfaced grid-connected converter with reduced-order
    (ISA - Instrumentation, Systems, and Automation Society, 2023-01) Long, Bo; Lu, PengJie; Zhan, Danny; Lu, Xin; Rodríguez, José; Guerrero, Josep M.; Chong, Kil to
    This paper proposes a discrete-time fuzzy fractional-order sliding-mode control (Fuzzy-FOSMC) dual loop current controller for a three-phase LCL-type grid-connected converter (GCC) with reduced order. Conventional sliding-mode control (SMC) has been widely used in GCC due to its robustness to disturbances. However, the chattering in SMC may reduce the tracking performance of the controller, and even lead to system instability. To solve this problem, a Fuzzy-FOSMC controller is proposed in this paper. The introduced fractional-order term can suppress the chattering, and the fractional-order of FOSMC is further adjusted by the fuzzy controller to improve the overall system performance. In addition, the inner loop is implemented by a Fuzzy-FOSMC controller to ensure the tracking of the converter-side current, making the LCL-GCC converter behave like a controllable current source converter with a capacitive-inductive filter, the grid current control problem falls from a third-order to a reduced order system, which solves some difficulties on the design of most controller types. The stability of the two-stage PV system is analyzed. Finally, the effectiveness of the proposed controller is verified by experiments. © 2022 ISA
  • 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.
  • No hay miniatura disponible
    Ítem
    MPC-Controlled Virtual Synchronous Generator to Enhance Frequency and Voltage Dynamic Performance in Islanded Microgrids
    (Institute of Electrical and Electronics Engineers Inc., 2021-03) Long, Bo; Liao, Yong; Chong, Kil; Rodríguez, José; Guerrero, Josep M.
    The use of high penetration converter-interfaced renewable energy (RE) based microgrids (MGs), due to the absence of rotational masses from conventional synchronous generators (SGs), may lead to a lack of inertia, which may lead the steeper frequency and voltage fluctuations that may in turn cause instability issues and challenges the normal operation of sensitive loads. To suppress these fluctuations and enhance the MGs stability, a novel model predictive control (MPC)-controlled virtual synchronous generator (VSG) for an energy storage system (ESS) is introduced. The proposed method can provide inertia support during transient states and enhance the dynamic characteristics of system voltage and frequency. By establishing the prediction model of VSG and designing the cost function for frequency and power, the increments of the needed active and reactive power are calculated then superposed on the power reference of VSG. The results show that the suppression performance of the voltage and frequency variations under loading transition with the proposed method is better than those of other techniques. Simulation and hardware-in-the-loop (HIL) results further demonstrate 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)
  • No hay miniatura disponible
    Ítem
    Voltage Regulation Enhancement of DC-MG Based on Power Accumulator Battery Test System: MPC-Controlled Virtual Inertia Approach
    (Institute of Electrical and Electronics Engineers Inc., 2022-01-01) Long, Bo; Zeng, Wei; Rodriguez, Jose; Guerrero, Josep M.; Chong, Kil To
    In a DC-microgrid (DC-MG) composed of a power accumulator battery test system (PABTS), owing to the low inertia of DC capacitance, the charging and discharging of a PABTS can easily cause DC-link voltage fluctuations, which may jeopardize the system stability. Hence, a virtual inertia control (VIC) strategy is proposed to suppress these fluctuations and enhance the stability of the DC-MG. The VIC method is realized in a bidirectional grid-connected converter (BGCC), which combines VIC and model predictive control (MPC). The proposed method can provide inertia support during the transient state and enhance the dynamic characteristics of the DC-link voltage. A prediction model is established that uses the variation range of the DC-link voltage as the constraint, and the output of VIC as well as voltage deviations as optimization objectives. The desired DC-link current increment is calculated using the prediction model to change the input DC current reference of the VIC. To validate the effectiveness of the proposed method, hardware-in-the-loop (HIL) experiments are performed, and the results indicate that MPC-VIC is superior to the existing VIC methods in terms of inertia support and the DC-link voltage variation suppression of PABTS DC-MGs. © 2010-2012 IEEE.