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Hybrid architectures are used in the Millimeter wave (mmWave) Massive MIMO systems, which use a smaller number of RF chains and reduces the power and energy consumption of the mmWave Massive MIMO systems. However, the majority of the hybrid architectures employs the conventional circuit configuration by connecting each of the RF chains with all the transmitting antennas at the base station. As a result, the conventional circuit configuration requires a large number of phase shifters, combiners, and low-end amplifiers. In this paper, we modify the RF circuit configuration by connecting each of the RF chains with some of the transmitting antennas of mmWave Massive MIMO. Furthermore, the hybrid analogue/digital precoders and decoders along with the overall circuit power consumptions are modelled for the modified RF circuit configuration. In addition, we propose the alternating optimization algorithm to enhance the optimal energy efficiency and compute the optimal system parameters of the mmWave Massive MIMO system. The proposed framework provides deeper insights of the optimal system parameters in terms of throughput, consumed power and the corresponding energy efficiency. Finally, the simulation results validate the proposed framework, where it can be seen that the proposed algorithm significantly reduces the power and energy consumptions, with a little compromise on the system spectral gain.

This study is concerned with the national transposition of the European Renewable Energy Directive into Austrian law. The objective is to estimate the economic viability for residential customers when participating in a renewable energy community (REC), focused on PV electricity sharing. The developed simulation model considers the omission of certain electricity levies as well as the obligatory proximity constraint being linked to grid levels, thus introducing a stepwise reduction of per-unit grid charges as an incentive to keep the inner-community electricity transfer as local as possible. Results show that cost savings in residential RECs cover a broad range from 9 EUR/yr to 172 EUR/yr. The lowest savings are gained by customers without in-house PV systems, while owners of a private PV system make the most profits due to the possibility of selling as well as buying electricity within the borders of the REC. Generally, cost savings increase when the source is closer to the sink, as well as when more renewable electricity is available for inner-community electricity transfer. The presence of a commercial customer impacts savings for households insignificantly, but increases local self-consumption approximately by 10%. Despite the margin for residential participants to break even being narrow, energy community operators will have to raise a certain participation fee. Such participation fee would need to be as low as 2.5 EUR/month for customers without in-house PV systems in a purely residential REC, while other customers could still achieve a break-even when paying 5 EUR/month to 6.7 EUR/month in addition. Those results should alert policy makers to find additional support mechanisms to enhance customers’ motivations to participate if RECs are meant as a concept that should be adopted on a large scale.

The ongoing study aims to establish a direct probabilistic load flow (PLF) for the analysis of wind integrated radial distribution systems. Because of the stochastic output power of wind farms, it is very important to find a method which can reduce the calculation burden significantly, without having compromising the accuracy of results. In the proposed approach, a K-means based data clustering algorithm is employed, in which all data points are bunched into desired clusters. In this regard, probable agents are selected to run the PLF algorithm. The clustered data are used to employ the Monte Carlo simulation (MCS) method. In this paper, the analysis is performed in terms of simulation run-time. Also, this research follows a two-fold aim. In the first stage, the superiority of data clustering-based MCS over the unsorted data MCS is demonstrated properly. Moreover, the impact of data clustering-based MCS and unsorted data-based MCS is investigated using an indirect probabilistic forward/backward sweep (PFBS) method. Thus, in the second stage, the simulation run-time comparison is carried out rigorously between the proposed direct PLF and the indirect PFBS method to examine the computational burden effects. Simulation results are exhibited on the IEEE 33-bus and 69-bus radial distribution systems.

Copper sinter paste has been recently established as a robust die-attach material for high -power electronic packaging. This paper proposes and studies the implementation of copper sinter paste materials to create top-side interconnects, which can substitute wire bonds in power packages. Here, copper sinter paste was exploited as a fully printed interconnect and, additionally, as a copper clip-attach. The electrical and thermal performances of the copper-sinter paste interconnections (“sinterconnects”) were compared to a system with wire bonds. The results indicate comparable characteristics of the sinterconnect structures to the wire-bonded ones. Moreover, the performance of copper sinterconnects in a power module was further quantified at higher load currents via finite element analysis. It was identified that the full-area thermal and electrical contact facilitated by the planar sinterconnects can reduce ohmic losses and enhance the thermal management of the power packages.

The transport sector generates more than 35% of total CO2 emissions. Electric vehicles are the future of transportation systems, and the demand for electric vehicles has grown considerably in the last few years due to government support. Companies worldwide are investing heavily in electric car charging stations based on renewable energy. This research study presents a complete design (including an appropriate energy management strategy) for a photovoltaic energy-based electric vehicle charging station (EVCS) with or without the support of a fuel cell and electrolyzer system. The parameters considered for designing the necessary capacity of the battery pack to support the required load are relative to the location-specific solar radiation (using RETScreen® Clean Energy Management Software, Version 9.0, Government of Canada, Toronto, Canada), the efficiency of the solar panel, the used strategy, etc. The battery capacity in the EVCS design based on a power-following strategy is about 20 times smaller than that resulting in the reference design. Additionally, the cost for an EVCS design based on a power-following strategy is almost half that resulting in the reference design. An analysis of the power-following strategy was carried out according to three EVCS operating scenarios.

Biogas plants can contribute to future energy systems’ stability through flexible power generation. To provide power flexibly, a demand-oriented biogas supply is necessary, which may be ensured by applying flexible feeding strategies. In this study, the impacts of applying three different feeding strategies (1x, 3x and 9x feeding per day) on the biogas and methane production and process stability parameters were determined for a biogas plant with a focus on waste treatment. Two feedstocks that differed in (1) high fat and (2) higher carbohydrate content were investigated during semi-continuous fermentation tests. Measurements of the short chain fatty acids concentration, pH value, TVA/TIC ratio and total ammonium and ammonia content along with a molecular biology analysis were conducted to assess the effects on process stability. The results show that flexible biogas production can be obtained without negative impacts on the process performance and that production peaks in biogas and methane can be significantly shifted to another time by changing feeding intervals. Implementing the fermentation tests’ results into a biogas plant simulation model and an assessment of power generation scenarios focusing on peak-time power generation revealed a considerable reduction potential for the needed biogas storage capacity of up to 73.7%.

Methanol synthesis from carbon dioxide (CO2) may contribute to carbon capture and utilization, energy fluctuation control and the availability of CO2-neutral fuels. However, methanol synthesis is challenging due to the stringent thermodynamics. Several catalysts mainly based on the carrier material Al2O3 have been investigated. Few results on MgO as carrier material have been published. The focus of this study is the carrier material MgO. The caustic properties of MgO depend on the caustification/sintering temperature. This paper presents the first results of the activity of a Cu/MgO catalyst for the low calcining temperature of 823 K. For the chosen calcining conditions, MgO is highly active with respect to its CO2 adsorption capacity. The Cu/MgO catalyst showed good catalytic activity in CO2 hydrogenation with a high selectivity for methanol. In repeated cycles of reactant consumption and product condensation followed by reactant re-dosing, an overall relative conversion of CO2 of 76% and an overall selectivity for methanol of 59% was obtained. The maximum selectivity for methanol in a single cycle was 88%.

The production of syngas with optimal energy usage, a minimal environmental impact, and an adjustable H2/CO molar ratio is possible using tri-reforming of methane (TRM). Despite the number of studies dedicated to the TRM process, this process is still in its infancy, with many technical obstacles to overcome. Except for its kinetics and catalysts, which have been reviewed elsewhere, the TRM process is evaluated thoroughly in this work. First, feasibility studies of TRM and the TRM process are presented. Second, the impacts of various operating conditions on the rate of gas conversions, syngas production, and coke formation are discussed. Third, different reactor configurations are compared. This review then goes through the energy and energetic efficiency, economic, environmental, and safety aspects of the TRM process. Finally, a research path for the future is suggested.