This paper presents a study by simulation of the performance of two of the current topologies for the interconnection of batteries and supercapacitors in a Hybrid Energy Storage System with potential application in electric microgrids. Converters selection is made taking into account the most used topologies documented in the literature for the integration of storage technologies. Control strategies are implemented pursuing the goal of prolonging the lifetime of batteries, using the supercapacitor for reducing the dynamic component of the current from a pulsed current load to the batteries.

Context:This paper presents a comparative study of the performance of three topologies for interconnecting Lithium ion batteries and supercapacitors in a hybrid energy storage system for use in electric residential microgrids with intermittent generation. The hybrid system’s main purpose is to prolong battery life, using the supercapacitor to handle the dynamic component of current from a pulsed current load. This work builds upon a preliminary simulation-based study, in which two semi-active topologies were compared and evaluated. Here, we add an active topology to the study and describe the operational benefits of each topology. Method:For every topology in this study, a non-isolated half-bridge bidirectional DC converter was used, and a proportional–integral (PI) double-loop linear ACC control algorithm was designed for controlling the converters. In the active topology an additional optimisation-based real-time frequencydecoupling control strategy was employed. Results:A parallel active topology allows better management of stored energy in the SC by supporting variation of SC terminal voltages with a DC converter as interface to the DC bus. Conclusions: Semi-active topologies are easier to design and control, but the operational benefits of supercapacitors require voltage variation at the terminals. This variation is made possible with an active topology. Acknowledgements: First author thanks Universidad Distrital Francisco Jos´e de Caldas for the financial support in his doctoral studies through the study commission contract N° 000101-2016.

In a microgrid composed of distributed active generators based on renewable energy sources, with heterogeneous features and generation profiles, the availability of the energy resource, the energy reserve capacity, and the degradation of the storage unit, define the constraints for the management and dispatch of each active generator. This can result in sub-optimal use of distributed energy resources in comparison with the operation of a single generation unit. However, under the current trend oriented to distributed installations, the overall operation could be improved if an aggregated operation is considered within the management level. This paper proposes a coordinated operation of the storage units associated with distributed active generators for a hybrid grid-connected microgrid. In order to optimize the use of the active generators, including the equalization of the state of charge of the storage units, a mathematical model is proposed. This model tries to avoid uneven degradation of the storage units, and, consequently, enhance the reserve capacity and reduce the depth of discharge by achieving the operation of the distributed system as a unified system. The simulations are carried out in GAMS and MATLAB in order to validate the system's operation. The results show a better performing grid-connected microgrid with the proposed approach.

Context: It is intended to conduct a technical study of a voltage transformer power core, used for the supply of the auxiliary services of a maneuver type substation, hoping to mitigate the possibility of losing the continuous electricity power supply and likewise reducing the dependency with the external supplier. This is a result of a collaborative project between the Bogota Energy Company and the Universidad Distrital Francisco Jose de Caldas. Method: The study consists of two stages, the first one is an analysis of reliability of the substation auxiliary systems, carried out in three scenarios: before and after use of the transformer and using a unique generator for auxiliary services. The second one is simulation using the ATP software to verify the behavior of the equipment in transient state. Results: The reliability of auxiliary services increased after the equipment has been installed, as the failure rate went from 0.31 [failure/year] with the current system, to become 0.0025 [failure/year]. Conclusions: The implementation of transformer is suitable for substations that do not have a reliable power system auxiliary services as it makes the substation auto dependent. Implement this system in Colombia would get a big increase in the reliability of the auxiliary services in maneuver type substations and therefore a lower probability of loss.