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This paper presents a new framework for optimal planning of electrical, heating, and cooling distributed energy resources and networks considering smart buildings' contribution scenarios in normal and external shock conditions. The main contribution of this paper is that the impacts of smart buildings' commitment scenarios on the planning of electrical, heating, and cooling systems are explored. The proposed iterative four-stage optimization framework is another contribution of this paper, which utilizes a self-healing performance index to assess the level of resiliency of the multi-carrier energy system. In the first stage, the optimal decision variables of planning are determined. Then, in the second stage, the smart buildings and parking lots contribution scenarios are explored. In the third stage, the optimal hourly scheduling of the energy system for the normal condition is performed considering the self-healing performance index. Finally, in the fourth stage, the optimization process determines the optimal scheduling of system resources and the switching status of electrical switches, heating, and cooling pipelines’ control valves. The proposed method was successfully assessed for the 123-bus IEEE test system. The proposed framework reduced the expected values of aggregated system costs and energy not supplied costs by about 49.92% and 93.64%, respectively, concerning the custom planning exercise. ; © 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). ; fi=vertaisarvioitu|en=peerReviewed|

Abstract In the paper a novel approach to thermochemical utilization of low rank coal, flotation concentrates and municipal refuse derived fuels was presented. The economic attractiveness of low rank coals and flotation concentrates is limited and that is why they are commonly stored at excavation heaps causing additional costs and the risk of endogenous fires occurrence. One of the crucial parameters determining the attractiveness and usability of a fuel in the gasification process is its reactivity. In the study several low rank coals, flotation concentrates and municipal refuse derived fuels were tested in terms of their reactivity in the process of steam gasification. The reactivity of low rank coal and flotation concentrates at 50% of carbon conversion, R50, varied between 1.46·10−4 and 2.39·10−4 s−1, whereas the maximum reactivity, Rmax, from 3.28·10−4 to 4.62·10−4 s−1. Advanced mathematical models were developed to investigate the similarities and dissimilarities between the studied fuels as well as the relationships between the physical and chemical parameters and the reactivities of fuel chars in steam gasification. On this basis, a low rank coal was selected and blended with 20%w/w of municipal refuse derived fuel in co-gasification experiments. The aim of the research was to utilize the low rank coal characterized by the lowest reactivities (R50 and Rmax of 1.46·10−4 and 3.28·10−4 s−1, respectively) in steam co-gasification to hydrogen-rich gas with an alternative fuel in a fixed bed reactor at the temperature of 800 °C. The selected low rank coal was blended with 20%w/w of municipal refuse derived and the resulting fuel yielded the average concentration of hydrogen in the produced gas of 58.99%vol.

Renewable resources and energy storage systems integrated into microgrids are crucial in attaining sustainable energy consumption and energy cost savings. This study conducts an in-depth analysis of diverse storage systems within multi-energy microgrids, including natural gas and electricity subsystems, with a comprehensive focus on techno-economic considerations. To achieve this objective, a methodology is developed, comprising an optimization model that facilitates the determination of optimal storage system locations within microgrids. The model considers various factors, such as operating and emission costs of both gas and electricity subsystems, and incorporates a sensitivity analysis to calculate the investment and maintenance costs associated with the storage systems. Due to the incorporation of voltage and current relations in the electricity subsystem as well as gas pressure and flow considerations in the natural gas subsystem, the developed model is classified as a mixed-integer nonlinear programming model. To address the inherent complexity in solving, a decomposition approach based on Outer Approximation/Equality Relaxation/Augmented Penalty is developed. This study offers scientific insights into the costs of energy storage systems, potential operational cost savings, and technical considerations of microgrid operation. The results of the developed decomposition approach demonstrate significant advantages, including reduced solving time and a decreased number of iterations.

Abstract This paper presents a two-level optimization problem for optimal day-ahead scheduling of an active distribution system that utilizes renewable energy sources, distributed generation units, electric vehicles, and energy storage units and sells its surplus electricity to the upward electricity market. The active distribution system transacts electricity with multiple downward energy hubs that are equipped with combined cooling, heating, and power facilities. Each energy hub operator optimizes its day-ahead scheduling problem and submits its bid/offer to the upward distribution system operator. Afterwards, the distribution system operator explores the energy hub’s bids/offers and optimizes the scheduling of its system energy resources for the day-ahead market. Further, he/she utilizes a demand response program alternative such as time-of-use and direct load control programs for downward energy hubs. In order to demonstrate the preference of the proposed method, the standard IEEE 33-bus test system is used to model the distribution system, and multiple energy hubs are used to model the energy hubs system. The proposed method increases the energy hubs electricity selling benefit about 185% with respect to the base case value; meanwhile, it reduces the distribution system operational costs about 82.2% with respect to the corresponding base case value.

Abstract Utilization of renewable energy sources (RESs) has been increased due to economic-environmental aspects. However, uncertain nature of wind, solar power, market clearing price (MCP), and load complicates the energy management (EM) process of microgrids. This paper studies the EM problem of a grid-connected microgrid from the generating side's perspective. Firstly, the mathematical formulation of microgrid components including wind turbine (WT), photovoltaic (PV), micro turbine (MT), fuel cell (FC) and energy storage system (ESS) has been presented. An improved incentive-based demand response program (DRP) is applied to provide generation-consumption balance by modifying the load pattern. Considering the intra-day market in the formulation of EM is the first contribution of this paper. Furthermore, a new hybrid copula-scenario based uncertainty modeling technique has been presented in this paper. Formulating operational cost and environmental pollution as the objective functions, the proposed EM problem will be solved by multi-objective group search optimization (MOGSO) algorithm. Simulation results demonstrate the good performance of the proposed method in solving microgrid EM problem.

One of the major issues associated with the implementation of direct-current distribution systems is the design of a proper protection scheme. The fault current characteristics in direct-current distribution systems are quite different than those in conventional alternating-current grids. Thus, the performance of conventional protection schemes can adversely be affected, and it is necessary to modify the con-ventional protection schemes or design new protection methods for direct-current networks. This paper proposes a multi-zone differential protection scheme for direct-current distribution systems embedding distributed generators. The proposed method provides a selective and fast protection through the use of a communication link between two sides of a protected feeder. Moreover, the method provides a differential-based backup for the adjacent relays, which can enhance the protection system reliability. In addition, the method proposed in this paper also utilizes directional over-current elements to provide backup protection if the communication network fails. The effectiveness of the proposed protection scheme is evaluated through comprehensive hardware-in-the-loop simulation studies to obtain more realistic results and to investigate the impact of the communication delay. The results show that the proposed method can provide a selective and fast protection and effectively protect components of direct-current distribution systems against different types of faults. Peer Reviewed

Abstract Two new cogeneration systems (producing power and heating) based on solid oxide fuel cell fed by either the syngas or biogas are proposed. The performance of systems is analyzed and compared with one another from the thermodynamic and economic viewpoints. Applying the conservation of mass and energy as well as the exergy and cost balance equations for each system component and using the engineering equation solver software, the systems are modeled. Through a parametric study, effects of some key variables such as the current density and the stack temperature difference on the systems' performance are investigated. It is found that for power generation, digester based solid oxide fuel cell shows better performance (with a first law efficiency of 40.14% vs 20.31%); however, considering the combined power and heating system, the total efficiency is obtained 51.05% and 58.75% for digester and gasifier based systems, respectively. In addition, it is found that the digester based SOFC is more cost-efficient and has 54% less unit product cost compared to that of the gasifier based system.

Abstract Elaborate design of highly efficient and durable electrocatalysts from earth-abundant elements is a milestone in the field of electrochemistry. In this study, heazlewoodite (Ni3S2) was successfully grafted on the silicon flour (Ni3S2@SiF) and ball-milled silicon flour (Ni3S2@B–SiF) through a simple hydrothermal process. The products were then etched using the HF solution to prepare the modified porous silicon (PSi) compounds of Ni3S2@PSi and Ni3S2@B–PSiF. Electrochemical studies showed that Ni3S2@B–SiF and Ni3S2@B–PSiF were not only durable but also exhibited electrocatalytic activity toward both alkaline and acidic hydrogen evolution reactions (HER) with appropriate Tafel slopes of 74 and 52 mV dec−1, respectively. Moreover, they recorded an electrocatalytic activity for the oxygen evolution reaction (OER) with an overpotential of 164 mV dec−1. Based on the electrocatalytic studies, the Ni3S2@B–PSiF electrocatalyst was found to have the best electrocatalytic behavior toward HER and OER. The isolated island architecture of the bi-functional (i.e., HER and OER) electrocatalyst could act as promising electrode materials for water splitting using electrochemical methods.