Examinando por Materia "Microgrids"
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- PublicaciónSólo datosControl of a Bidirectional Cûk Converter Providing Charge/Discharge of a Battery Array Integrated in DC Buses of Microgrids(Applied Computer Sciences in Engineering, 2017-10-01) López-Santos, Oswaldo; Zambrano-Prada, David; Aldana-Rodríguez, Yeison A.; Esquivel-Cabeza, Harold A.This paper presents a proposal to charge and discharge valve-regulated lead-acid (VRLA) battery arrays integrated into microgrids by using the bidirectional Cûk converter with a multi-mode multi-loop control scheme based on sliding-mode control. The proposed control integrates the constant current - constant voltage - constant voltage charge method (CC-CV-CV) which is implemented using an inner current loop based on the sliding mode control of the input current of the converter and two nested outer loops based on the voltage and current of the battery. Conversely, the discharge is studied using two operational modes, one using a current reference given by a high level on a hierarchical structure and other using a current reference given by an outer Proportional-Integral (PI) controller regulating the voltage of the DC bus. The modelling of the bidirectional Cûk converter in these applications and its operational modes besides the analysis of the inner loop and the design criteria used in the synthesis of the outer loops are addressed. Simulation results are presented validating the control proposal.
- PublicaciónSólo datosEvent-Triggered Digital Implementation of MPPT for Integration of PV Generators in DC Buses of Microgrids(Applied Computer Sciences in Engineering, 2018-09-13) López-Santos, Oswaldo; Merchán-Riveros, María C.; García, GermainThis paper presents an event-triggered approach to optimally implement a Maximum Power Point Tracking (MPPT) algorithm into a Digital Signal Processor (DSP). The proposed method allows improving the amount and distribution of time required for executing control tasks. The used nested loop control architecture has an outer loop of MPPT generating the conductance reference used by an inner loop which regulates the input conductance of a DC-DC converter. This last loop enforces a sliding-mode loss-free-resistor behavior for the power converter by means of a simple hysteresis comparator. Computations required by the MPPT algorithm are synchronously executed by the two possible commutation events produced by the inner loop during a switching period. Then, the acquisition of signals must be activated only at an instant before each one of the switching events, releasing the most of the time to implement other tasks. This last characteristic and the use of a nested loop control architecture facilitate the integration of the other essential control functions for photovoltaic (PV) generators in microgrids. Simulation and experimental results confirm the high potetialities of this implementation approach.