Single-Phase Grid-Connected Battery-Supercapacitor Hybrid Energy Storage System

Battery technology is popular in distributed energy storage systems (ESSs) due to its ease of implementation. However, batteries have limited power capabilities, and the lifetime of batteries deteriorates due to high and fluctuating battery currents. Battery-supercapacitor hybrid energy storage systems (HESSs) become a promising way of increasing the battery lifetime and system power capability. The HESSs can be divided into two groups, DC link based and direct AC line integrated HESSs. The direct AC line integrated HESSs have been proposed to eliminate multiple power processing stages associated with the DC link based HESSs.The objective of this research is to develop a direct grid-connected battery-supercapacitor HESS able to allocate fast power fluctuations to the supercapacitor while maintaining the state of charge of the ESSs within a safe operating region. Since the lifetime of ESSs deteriorates with ripple current components, ways of reducing the current ripple components of the ESSs are studied.In this thesis, a boost inverter based battery-supercapacitor HESS is proposed. A supercapacitor voltage controller and a filter based method is used to allocate the fast power fluctuations to the supercapacitor. Then, a supercapacitor energy controller (SCEC) based power allocation method facilitating the HESS dynamic analysis and precise supercapacitor sizing is proposed. Later, a sliding mode controlled HESS with a SCEC based power allocation method is proposed to achieve better output voltage reference following performance. To mitigate the second-order harmonic current components in the boost inverter based HESSs, a rule-based control method and a novel current feedback method are proposed. Both methods achieve a significant ripple current reduction without being affected by the output capacitor tolerances while the latter method mitigates the current ripple even during the output power transients.The proposed HESS is the first experimentally verified single-phase direct grid-connected HESS able to reduce the switching frequency and the second-order harmonic current ripples

Energy management on battery/ultracapacitor hybrid energy storage system based on adjustable bandwidth filter and sliding-mode control

A real-time power-split control strategy for a hybrid energy storage system (HESS) used in electric vehicles is proposed in this work. The HESS topology corresponds to a semi-active ultracapacitor (UC) configuration. The HESS goals are to prevent battery degradation and to preserve its lifetime while improving the system efficiency by supplying the fast dynamics power demands through the UC pack. In order to generate the UC power reference, a digital low-pass filter whose bandwidth is adjusted according to the UC SOC is proposed. This allows a better usage of the UC available energy, while reducing frequent activation of controller protections and avoiding the calculation of the filter cut-off frequency for a certain driving cycle. The low-level control strategy is based on a sliding mode controller combined with a closed-loop current observer, which allows to improve the implementation performance while maintaining the current ripple bounded. Simulation and experimental results were presented showing that the proposed strategy preserves battery health in a more effective way than filter-based strategies with fixed bandwidth, for cases where no future information about the required power is available.Fil: Asensio, Eduardo Maximiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Magallán, Guillermo Andrés. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: de Angelo, Cristian Hernan. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Serra, Federico Martin. Universidad Nacional de San Luis. Facultad de Ingeniería y Ciencias Agropecuarias. Laboratorio de Control Automático; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin