Description: Energies, Vol. 10, Pages 1847: Design and Control of a Buck–Boost Charger-Discharger for DC-Bus Regulation in Microgrids Energies doi: 10.3390/en10111847 Authors: Carlos Andrés Ramos-Paja Juan David Bastidas-Rodríguez Daniel González Santiago Acevedo Julián Peláez-Restrepo In DC and hybrid microgrids (MG), the DC-bus regulation using Energy Storage Devices (ESD) is important for the stable operation of both the generators and loads. There are multiple commercial voltage levels for both ESD and DC-bus; therefore, the ESD voltage may be higher, equal or lower than the DC-bus voltage depending on the application. Moreover, most of the ESD converter controllers are linear-based, hence they ensure stability in a limited operation range. This paper proposes a system to regulate the DC-bus voltage of an MG accounting for any voltage relation between the ESD and the DC-bus voltage. The proposed system is formed by an ESD connected to a DC-bus through a bidirectional Buck–Boost converter, which is regulated by a Sliding-Mode Controller (SMC) to ensure the system stability in the entire operation range. The SMC drives the Buck–Boost charger–discharger to regulate the DC-bus voltage, at the desired reference value, by charging or discharging the ESD. This paper also provides detailed procedures to design the parameters of both the SMC and the charger–dischager. Finally, simulation and experimental results validate the proposed solution and illustrate its performance.

Description: Energies, Vol. 11, Pages 1389: Impact of Risk Aversion on the Operation of Hydroelectric Reservoirs in the Presence of Renewable Energy Sources Energies doi: 10.3390/en11061389 Authors: Nenad Jovanović Javier García-González Santiago Cerisola Julián Barquín The increasing share of renewable energy sources, such as wind and solar generation, has a direct impact on the planning and operation of power systems. In addition, the consideration of risk criteria within the decision support tools used by market participants (generation companies, energy services companies, and arbitrageurs) is becoming a common activity given the increasing level of uncertainties faced by them. As a consequence, the behavior of market participants is affected by their level of risk aversion, and the application of equilibrium-based models is a common technique used in order to simulate their behavior. This paper presents a multi-stage market equilibrium model of risk-averse agents in order to analyze up to what extent the operation of hydro reservoirs can be affected by the risk-averse profile of market participants in a context of renewable energy source penetration and fuel price volatility.