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Summary: In light of the increasing share of renewable energy sources (RES) in electricity generation, the research community is directing their attention toward developing highly efficient DC‐DC high‐gain step‐up converters. These converters are designed to exhibit reduced voltage stress on the switching devices (semiconductors). This paper presents a comprehensive study of a switch voltage stress‐reduced step‐up converter that offers a range of additional features, including the availability of a common ground point, continuous input current, simple two‐mode continuous conduction mode (CCM) operation, wide duty cycle range, and quadratic boosting factor. To achieve the aforementioned features, the converter utilizes two switches with the same operating modes, eliminating the need for complex switching circuitry. Operational modes, steady‐state analysis, and design considerations have been presented in detail. Comparative analysis indicates that the voltage conversion ratio per number of devices in the proposed topology is significantly higher than that of similar topologies. In addition, the voltage stress of switches is considerably less than the topologies addressed in the literature. The study further includes detailed mathematical and experimental analyses, small signal analysis, and hardware implementation to support the theoretical findings. The converter's efficiency has been thoroughly analyzed along with thermal analysis to ensure its reliability. [ABSTRACT FROM AUTHOR]

The global drive to achieve the climate change mitigation targets set during the Paris Agreement and COP26 necessitates sustainable electricity generation from renewable energy sources. However, renewable energy systems face economic challenges due to unattractive feed‐in‐tariffs (FiT). This paper presents a mathematical programming model to optimise the participation and electricity generation by biomass power plants in a FiT programme. A disjunctive fuzzy optimisation approach is adopted in this work due to the presence of several biomass power plants, thus resulting in a multi‐objective optimisation. The newly developed mixed‐integer linear programming (MILP) model maximises the overall satisfaction extent of biomass power plants in power generation. The optimisation model ensures the satisfaction of all biomass power plants' technical and economic constraints. A base case study of seven power plants utilising various palm biomass is used to demonstrate the disjunctive fuzzy optimisation approach for the MILP model. This is followed by a scenario investigating the impact of demand variation. The optimisation of the case studies favours the utilisation of empty fruit bunch (EFB), palm oil mill effluent (POME), and palm mesocarp fibre (PMF) for sustainable electricity generation. Palm kernel shell (PKS) is the least preferred palm biomass due to its lowest net availability of useful energy from biomass combustion. This work provides a decision tool for the selection of biomass type during electricity generation. The MILP model in this work may be readily extended for any number of power plants, handling a variety of biomass feedstocks. [ABSTRACT FROM AUTHOR]

Considering the broad range of applications, efficient retrieval and storing electrical energy methods are still challenging. Besides the load variations, the ever‐increasing intermittent renewable energy penetration into the grid system has witnessed the system complexities. In off‐grid applications, energy storage can balance electricity consumption and electricity generation to avoid voltage and frequency deviations. This research paper focuses on the energy management of an off‐grid climate refuge system used for hot and arid locations with a system comparison for two routes of different storage techniques, namely flywheels and a lithium‐ion battery. The proposed system can generate its power from photovoltaics and provide cooling and other auxiliaries through vapor compression cycle and water misting units with an operation of about 16 hours (ie, from 7:00 am to 11:00 pm) on the weekdays and 12 hours on the weekends. A comparison of levelized costs is conducted for the evaluation using HOMER software. The annual energy production by solar photovoltaics for the proposed system is 20 MWh, and the annual consumption is 16 MWh. The photovoltaic‐battery storage system has shown the lowest cost of electricity, corresponding to 0.761 $/kWh, and net present cost of $66 238 and is optimum in all sensitivity analysis cases. [ABSTRACT FROM AUTHOR]

Although FRT capability is claimed in Japanese grid code for RE, DVS capability is not. In some European countries, not only FRT but also DVS is claimed. Whether this choice of our grid code is pragmatically adequate or not? To answer the question, it is necessary to evaluate FRT and DVS capabilities. But the past studies only evaluated qualitative merit of FRT and DVS, or evaluated quantitative merit on fictional system models. Since the authors intend to evaluate FRT and DVS capabilities in existing power system of Japan, some method for the evaluation must be invented. For the evaluation, values of FRT and DVS capabilities are evaluated by reduction amount of stabilizing equipment (i.e. SVC in the paper). The evaluation based on strict optimal SVC disposition is quite difficult, because existing power system must be adequately modeled, because number of SVCs is large and because every power flow conditions must be considered. However, semi‐optimal SVC disposition can be calculated as shown in the paper. As the result, value of FRT is quite larger than value of DVS. And then, our grid code is proved as pragmatically adequate, except some flaw in claimed FRT design that is introduced in the paper. [ABSTRACT FROM AUTHOR]

This paper proposes a real‐time generation regulation system named as "on‐demand generation regulation control" system, which is suitable for small independent power grids with unstable renewable energy generators. It has been developed as a part of "robust demand and supply control manager" and plays an important role of flexible frequency control that includes vehicle to grid and generation restriction when necessary. The main feature of the system is the integrated framework to effectively deal with hard‐to‐predict control options in a flexible way by observing the unstable generator outputs and all generators/batteries status including electric vehicles. In addition, a feedback system is also proposed to flexibly adjust the regulation capacity in case unexpected disturbances occur. The performance of the proposed system is verified through numerical simulations based on an actual test site with successful results. [ABSTRACT FROM AUTHOR]

In the future, renewable energy (RE) generation systems will be constructed and interconnected to the power system by nonutility entities such as generation companies and residential customers. Therefore, generation expansion planning (GEP) should consider the effects of RE generation. The purpose of this paper is to discuss the best GEP from the economic, supply reliability, and environmental aspects considering the penetration of RE generation. For this purpose, this paper proposes a model of a utility's GEP process considering RE generation. The proposed method is based on stochastic dynamic programming (SDP) in which long-term uncertainties are modeled by geometric Brownian motion (GBM) and the binomial lattice process. The variation of RE generation output due to the weather conditions (short-term uncertainty) is also considered in the proposed method by means of the net load curve. [ABSTRACT FROM AUTHOR]

This paper proposes a new method which produces electric energy by utilizing the density difference of water by means of a “chimney effect.” The density difference of water occurs in two ways, i.e., differences of water temperature and consistency of suitable materials such as salt. For instance, water heated by solar energy is pointed out as an example of the former, while fresh water of a river versus seawater and seawater versus concentrated salt water may account for the latter. This paper also considers the three foregoing cases in a practical way. The analysis estimates that the proposed method generates energy of several hundreds or more, and ten thousands and millions of kilowatts in the respective cases. The amount of energy extracted in the third case is compared with that of the usual electric power stations using nuclear energy. The method is considered as a kind of so-called renewable energy conversion system which is free of CO2, high-energy density and is controllable. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (2): 10–18, 1997 [ABSTRACT FROM AUTHOR]

SUMMARY Under the anticipated high penetration of variable renewable energy generation such as photovoltaics and higher share of nuclear generation, the issue of supply-demand balancing capability should be evaluated and fixed in a future power system. Improvement of existing balancing measures and new technologies such as demand activation and energy storage are expected to solve the issue. In this situation, a long-range power system supply-demand analysis should have the capability to evaluate the balancing capability and balancing countermeasures. This paper presents a new analysis methodology of activated demand model and evaluation of supply-demand balancing capability for a long-range power system demand-supply analysis model, ESPRIT. Model analysis was made to verify the new methodology of the tool including day-ahead scheduling of a heat pump water heater, an EV/ PHEV, and a battery. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(2): 21-30, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22488 [ABSTRACT FROM AUTHOR]