Search

The extensive electrification process that is taking holds in several applications makes increasingly necessary the virtualization of electric components for energetic and performance assessments during the system design stage. For this purpose, this article proposes a straightforward methodology for computing the efficiency maps of induction machines (IMs) operated in wide torque-speed ranges. The modeling approach is based on the IM equivalent circuit defined in the rotor dq coordinates. The procedure allows computing a set of efficiency maps at different machine temperatures and supply voltage levels, both for motor and generator operation modes. The equivalent circuit parameters at different frequencies and voltages are determined by means of the well-known no-load and locked-rotor tests, thus including in the modeling the machine nonlinearities, skin effect and the iron losses. The proposed methodology has been validated on a 10 kW, four-pole IM. The comparison between computed and experimental efficiency maps for different operating conditions, confirm the validity of the proposed methodology. [ABSTRACT FROM AUTHOR]

Multiphase drives are the subject of great interest for the transportation electrification. Multi-three-phase machines are used with modular three-phase converters to obtain a redundant structure and their great advantage is the fault-tolerance capability. Starting from a symmetrical multi-three-phase machine, a reconfigurable architecture drive can be obtained. The main characteristic of a reconfigurable architecture is the ability to change the winding configuration to better match the operating point, specifically the machine speed. The main advantage of this architecture is the capability of reducing the number of active converters when the machine operates at low speed, thus reducing total converter power losses. However, system complexity increases, since reconfiguration cells are needed to interconnect the winding sets. The proposed reconfigurable multi-three-phase drive architecture exhibits two main benefits at low speed operation: increased efficiency and reduced phase current ripple for a given switching frequency. The reconfigurable architecture was assessed by means of analytical as well as numerical simulations, and the benefits obtainable at low speed operation were also demonstrated experimentally on a reduced scale prototype, capable of “on the fly” reconfiguration without stopping the machine. [ABSTRACT FROM AUTHOR]

Applying 0.3–1.25 kV/cm electric potential gradients to cooled water vapor triggers the copious formation of electrified ice needles, as long as 36 mm. This is completely different from the meager ice formation in the same setup but in the absence of the external field. Needle excess electric charge is evidenced by its attraction toward the electrodes and by its shape change, when the field is withdrawn. These observations are explained considering the effect of the electric potential on ice surface tension, thus decreasing or eliminating the energy barrier to ice nucleation; and the elongated ice habit that allows the accumulation of charge sufficient to create fields higher than those initially applied. Applying this information to other crystallization phenomena in various systems can contribute to improve industrial processes while preventing the consequences of undesired electrification, in industrial plants and products. [ABSTRACT FROM AUTHOR]

Recent advancements in aircraft electrification have led to the introduction of turboelectric distributed propulsion (TeDP). For instance, NASA's N3X airplane aims to curb jet fuel emissions with the aid of TeDP. However, it is crucial to analyze the survivability of the TeDP system during extreme conditions. The endogenous failure events are of specific interest as they were found to cause a significant number of accidents for commercial aircraft. While the distribution reconfiguration is necessary to meet the critical load demands under extreme failure events, it can also create a transient overload condition in the turboshaft engine. The power system survivability is further deteriorated in the presence of constant power loads. In this article, a mathematical analysis of the survivability of the system is presented to make the aircraft power system highly resilient to endogenous failure events. A power system collapse mitigation strategy is proposed by adding an energy storage system. Moreover, the analytical expressions are formulated to size the energy storage unit to prevent the system collapse. Various failure conditions are modeled using PSCAD/EMTDC to study the minimum energy storage required to prevent system collapse. [ABSTRACT FROM AUTHOR]

This article proposes an integrated assessment methodology aimed at supporting decision-makers in design energy production scenarios to power a low emissions traffic fleet. The Multidimensional Air Quality (MAQ) system is used to define and solve a decision problem that selects a set of energy production scenarios minimizing costs, impacts on air quality, and greenhouse gases (GHGs) emissions. This study focuses on the road transport sector, that is responsible for 25% of European GHGs emissions and 39% of NOx emission, a precursor of both NO2 and PM10 concentrations. The electrification of the light vehicle fleet and the use of biomethane to power heavy vehicles are analyzed, estimating the electricity demand increase, exploring different energy production mixes, and assessing the impacts on air quality, costs, and GHGs according to the fuels/sources used to satisfy the energy demand. A case study over Lombardy region, in Northern Italy, is proposed. Note to Practitioners—The study designs a new decision problem implemented and solved through the Multidimensional Air Quality system (MAQ), an integrated assessment modeling tool. Such system integrates a set of databases, models, optimization, and enumeration algorithms. Composing these elements, specific multiobjective decision problems can be designed defining domain (mesoscale, regional, urban), objectives (air quality index, greenhouse gas emissions, costs, population exposure, health impacts), decision variables (technologies, behavioral measures, energy production, fuel switch), and constraints. MAQ system allows the comprehensive analysis of energy, technological, behavioral policies estimating impacts on air quality, human health, GHGs emissions, and costs. [ABSTRACT FROM AUTHOR]

An electric potential appears at floating wires located within a strong electric field. This phenomenon can be used to supply small isolated communities situated close to Extra-High Voltage transmission lines. This non-conventional distributed generation system has been studied for the last years. However, to improve the power generation system the optimal position of the floating wires, number of wires used, bundle radius, and type of wires must be properly identified. This paper presents a mathematical model solved with genetic algorithm to design a collector system with optimized induced voltage and minimized project cost, identifying the optimal reactor used for voltage regulation. The algorithm was applied to design a collector system that can tap-off 100 kW from a 230 kV transmission line. The trade-off between objectives and the Pareto optimal solutions were evidenced via several simulations using the weighting sum approach. These results allowed to identify a final geometry according to a-posteriori designer preferences. [ABSTRACT FROM AUTHOR]

The research on ship electrification is gaining renewed interest to take advantage of the numerous benefits offered by microgrids in the development of an all-electric ship (AES). A key aspect of the AES is in planning of cost effective and resilient shipboard power system (SPS). The integration of energy storage system (ESS) in SPS is found to help achieve this goal. An ESS can improve the fuel economy of diesel generators by regulating their load demand and provide emergency power promptly whenever necessary. This article proposes a planning strategy for sizing and siting of a special ESS integration configuration, distributed cloud ESS (DCESS), in the SPS. While the aim of DCESS sizing is minimizing the total cost of SPS, the objective of DCESS siting is to enhance the resilience of SPS. By stochastic programming, the optimal solution with respect to representative operating conditions and fault scenarios is obtained. The proposed DCESS configuration would facilitate easy power exchange among the electrical zones. A comparison with the conventional ESS configuration is presented and the benefit of DCESS configuration on resilience enhancement is demonstrated. [ABSTRACT FROM AUTHOR]

Microgrids play a pivotal role in the attempts to achieve universal access to electricity; hence, their accurate planning, which also includes the evolution of the system over the project lifetime, is essential for maximizing the profitability of the investments. This paper proposes an iterative multi-year mixed-integer linear programming (MILP) optimization, in which power-dependent efficiency and capacity degradation of storage as functions of the operative strategy are considered. In this study, the computational burden of such a large problem is significantly reduced by means of an external loop that accounts for the hourly storage efficiency and residual capacity and serves to update the parameters for the MILP optimization of the following iteration. This approach is tested on a case study of a community in Soroti, in central-eastern Uganda. Comparison with the output of a one-shot MILP and with a procedure that overlooks the effects of the dispatching strategy on storage characteristics is shown, highlighting the benefits gained with the proposed algorithm in terms of both simulation time and accuracy of the design. [ABSTRACT FROM AUTHOR]

In this article, a module-based plug-n-play (PnP) dc microgrid (MG) is introduced to help rural electrification. It provides a bottom-up way to form an MG with multilayer expandability and PnP feature. The module-based MG overcomes the drawback of conventional MG that requires central design and implementation which leads to high upfront cost and long lead time. It provides an organic way to form an MG that allows user to scale up the system as their demands grow, and fully utilize the existing resources. The proposed MG module is expandable on different layers that can meet the requirements of customers with different power consumption requirements. Each module, which contains PV generation and energy storage, can work as a stand-alone solar home system. Multiple modules can be connected as a group to scale up the local power supply. Groups can be interconnected through a public bus with gateway converter modules to form a community network, which can supply public usage and enable power exchange in a community range with relatively high distribution efficiency. The control of the proposed MG is in a fully decentralized manner such that central control and communication network can be omitted, which makes the system more user-friendly and highly robust. Detailed design, analysis, and implementation of the proposed PnP MG is provided in this article. Simulation and experimental results have been provided to verify the concept and analytical study. [ABSTRACT FROM AUTHOR]

In this article, a distributed incremental adaptive filter (DIAF) controlled utility interfaced photovoltaic (PV) - battery microgrid system is presented with power quality features. From protection aspects, grid tied solar inverters are required to shut down at loss of the utility. However, the multi-purpose PV-battery system is developed to provide energy to the critical loads, even at loss of distribution network. The bidirectional controlled converter with a battery also mitigates the intermittency of a PV array under rapid variations in the weather. The extracted maximum power is supplied to the voltage source converter (VSC), which is transferred to the nonlinear loads and the utility. The distributed incremental adaptive filter is used to control the VSC with contribution of PV power and the battery. In addition, the DIAF control provides harmonics mitigation, load balancing and power factor improvement functionalities in order to deal with system connected with nonlinear loads. A PV power feed-forward (PVFF) term is incorporated in the current control for injection of active power to the utility as well as to improve the dynamic operation of residential PV-battery microgrid. The battery energy storage (BES) reduces the fuel bills and it is also utilized to provide smoothing attributes to the microgrid. The effectiveness of PV-battery microgrid is validated experimentally developed in the laboratory. [ABSTRACT FROM AUTHOR]

Photovoltaic solar home systems (SHSs) provide a cost-effective solution for the limited electrification of remote off-grid communities. However, due to their standalone nature, the benefit of usage diversity cannot be extracted. In this paper, we present the power electronic interface along with the decentralized control scheme for the integration of standalone SHSs for driving community load applications. Power electronic interface consists of an isolated boost converter capable support dc bus integration, thereby it formulates a dc microgrid through the interconnection of multiple standalone SHSs. Power aggregation is achieved through decentralized controlled resource sharing based upon the resource availability and installed capacity in the individual solar home system. To ensure cost affordability and to avoid the deployment of any communication infrastructure, modified I–V droop control is designed for the intended application. Thereby, power aggregation through the proposed power electronic interface and its decentralized control allows us to extract the benefit of usage diversity and drive high power community power loads at a village scale. The overall schematic is simulated using MATLAB and scaled down model is implemented on hardware. Results of power aggregation from various resource sharing scenarios are illustrated. [ABSTRACT FROM AUTHOR]

DC microgrids built through a bottom-up approach are becoming popular for swarm electrification due to their scalability and resource-sharing capabilities. However, they typically require sophisticated control techniques involving communication among the distributed resources for stable and coordinated operation. In this work, we present a communication-less strategy for the decentralized control of a photovoltaic (PV)/battery-based highly distributed dc microgrid. The architecture consists of clusters of nanogrids (households), where each nanogrid can work independently along with provisions of sharing resources with the community. An adaptive I–V droop method is used, which relies on local measurements of state of charge and dc bus voltage for the coordinated power sharing among the contributing nanogrids. PV generation capability of individual nanogrids is synchronized with the grid stability conditions through a local controller, which may shift its modes of operation between maximum power point tracking mode and current control mode. The distributed architecture with the proposed decentralized control scheme enables 1) scalability and modularity in the structure, 2) higher distribution efficiency, and 3) communication-less, yet coordinated resource sharing. The efficacy of the proposed control scheme is validated for various possible power-sharing scenarios using simulations on MATLAB/Simulink and hardware-in-the-loop facilities at the Microgrid Laboratory, Aalborg University. [ABSTRACT FROM AUTHOR]

This paper analyses low-cost techniques for rural electrification based on the use of insulated shielding wires of extra-high-voltage transmission lines. The main idea is to use the line capacitive coupling as an auxiliary power supply to remote rural systems. The insulated shielding wire (ISW) will behave as a capacitive voltage divider, promoting low voltage on it. We introduce a comparison of different low-cost electrification methods used over the last years and present a careful analysis of different topologies, which have a major impact on rural voltage regulation. A transient study was implemented to observe the behavior of both the transmission system and the rural feeder under typical switchings. [ABSTRACT FROM AUTHOR]

There is a profound misalignment between the state of network coverage and phone ownership and the state of electrification across sub-Saharan Africa. While about 83% of the sub-Saharan population is covered by a mobile network and nearly 70% has a mobile subscription, only 33% can access electricity [1]-[3]. This problem is particularly acute in rural areas, where network access and penetration lag slightly but electrification is far lower [4]. We term this condition the mobile-electrification gap (MEG.) Faced by the MEG, rural sub-Saharans options for phone charging are few and undesirable. As mobile growth has outstripped electrification on the continent, sub-Saharans have turned to limited off-grid solutions or to resold electricity from "phone shops" to fill the void; some have even taken to shipping their phones to get them charged [5]. [ABSTRACT FROM AUTHOR]

This paper addresses the microgrid expansion planning problem. In such a competitive electricity market, it will assist community microgrid (COMG) companies in deciding whether or not they should invest in microgrid installation. A two-stage stochastic optimization approach is proposed to eliminate the traditional centralized planning, which has led to competition among COMGs, generation companies (GENCOs), and transmission companies (TRANSCOs) for power delivery. The objective of the two-stage stochastic programming model is to maximize the expected revenue from these three power companies while ensuring the cost-effectiveness and reliability of the power system under uncertain factors, such as load growth and component outages. The proposed model is solved by decomposing the planning problem into two stages. The goal of the first stage is to maximize the profits of COMGs, GENCOs, and TRANSCOs; the goal of second stage is to minimize short-term operation cost considering uncertainty to enhance the reliability of the system. Computational results from two IEEE test systems are presented to analyze the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

The article lists the editors of the IEEE Industrial Electronics Society including Kamal Al-Haddad, Milos Manic, and Dave Irwin.

Most of the third-world rural areas, especially in sub-Saharan Africa, are still without electricity. The few existing off-grid and upcoming installations are remote and characterized by limited resources that call for drastic conservation measures. For the majority of these emerging consumers, lighting is the priority load. Rural electrical lighting load models are characterized by inaccuracies due to technical omissions, highlighted in this paper, and result in energy wastage. Solutions to the third-world problems need not follow similar paths to those of the developed world. In fact, cutting-edge technologies like the cell phone have already leapfrogged rural communications where expensive infrastructure had been perennially cited as the impediment. In this paper, an-other futuristic technology, the white light emitting diode (LED), for general lighting, is poised to create yet another revolution in African rural electrification. [ABSTRACT FROM AUTHOR]

This paper presents a method based on evolution strategies for designing large rural low-voltage (Iv) distribution networks. Planning rural lv distribution networks involves radial configuration design, location of medium-voltage/low-voltage substations, and minimum cost. In this work, these goals are considered by taking into account different conductors, voltage drop and conductor capacity constraints, power losses in lines, and deterministic loads. The algorithms developed in this paper are based on evolution strategies (ES) and were implemented on large-scale rural Iv distribution networks, but they could also be used in general network optimization. [ABSTRACT FROM AUTHOR]

Develops a computer aided electrification design software for large scale rural electrification program in South Africa. Importance of the software in distribution transformer locations delineation; Implication of optimum transformer zone delineation on cable lengths and transformer utilization; Relevance of the software in searching alternative design strategies.

Presents a study that discusses questions concerning the frequency and duration of voltage sags, swells and surges posed by rural electric secondary power systems. Characteristics of the utilization voltage levels at rural sites; Statistical characteristics of voltage sags; Details on the result of the survey conducted in relation with the issue.

Examines electrical codes and standards applied specifically to rural applications. Recommendations on effective application of the documents; Information on basic motor circuits with electrical code references; Details on electrical protective devices.

Presents information on the Cua-Bocay (PCB) rural electrification project which are led by a nongovernmental organization (NGO) in Nicaragua. Participation of NGOs in the development activities in Nicaragua; Brief background on the Cua-Bocay municipality; History of the project; Changing goals in the PCB project; Infrastructure and programs of the PCB; Project benefits and training emphasis of PCB; Project costs; Benefits and transformations of PCB project.