Electrical Constraints Research Articles

Coordinated Planning of Extreme Fast Charging Stations and Power Distribution Networks Considering On-Site Storage

The extreme fast charging (XFC) technology helps to reduce refueling time, alleviate mile anxiety, extend driving range and finally promote the popularity of electric vehicles (EVs). However, it would also pose great challenges on the power grid infrastructure especially distribution networks, due to the large-scale and intermittent power demand. This paper proposes a coordinated planning method for power distribution networks and XFC EV charging stations, with the on-site batteries considered. Firstly, considering the traffic flow pattern, the operation of XFC stations is analyzed on both energy and power demand. Secondly, the coordinated planning model is developed to satisfy the time-varying XFC load, with both transportation and electricity constraints considered. In addition, the on-site batteries are introduced to flatten the XFC energy used and supplement its power supply. The case studies have verified the effectiveness of the proposed method. The influence of XFC on the distribution networks and the effects of the on-site storage are also studied.

A GIS-based approach for high-level distribution networks expansion planning in normal and contingency operation considering reliability

This paper presents a novel methodology for the Distribution Networks expansion planning based on Geographic Information Systems. The proposed methodology combines Delaunay Triangulation with a Mixed-Integer Linear Programming model in a 2-steps approach. Secondary substations are grouped in primary substation clusters, considering both normal and contingency operation. Topological and electrical constraints have to be fulfilled as well as a given level of reliability; the mathematical formulation includes feeder and substation constraints. The proposed methodology is expected to be only the first step of the whole network expansion planning. Hence, it has to be able to give macro information that planners can refine in the following steps of the planning process. A numerical case study on a real network illustrates the effectiveness of the proposed approach for the Distribution Network expansion planning problem.

A modified incremental gravitational search algorithm for short-term hydrothermal scheduling with variable head

In this study, the solution of short-term hydrothermal coordination problem (STHCP) with variable head was performed. In the manuscript, incremental gravitational search algorithm (IGSA) which was developed as a new method has been applied to two different power problems. One of the systems used as an example is a variable head STHCP which has previously been solved in the literature by neglecting transmission line losses. The second is a lossy system designed as a variable head STHCP, with the purpose of contributing to the literature. In the lossy system, Newton–Raphson AC power flow method was used to calculate transmission line losses. Possible electrical and hydraulic constraints in the solution of the problem were satisfied using the penalty function method. The results obtained from the solutions of the sample systems were compared and discussed.

Metamagnetoelectric effect in multiferroics A2Cu2Mo3O12 (A=Rb and Cs) quantum spin chain

The magnetoelectric and thermodynamic properties of multiferroic A2Cu2Mo3O12 (A=Rb and Cs) compounds are investigated through the theoretical laboratory of a frustrated one-dimensional spin chain of CuO2 ribbon where inter-chain couplings are ignored. The general framework is built under external magnetic and electric field constraints with additional anisotropies. The field scans of magnetoelectric properties highlight a set of interdependent meta-transition giving birth to the metamagnetoelectric effect. Those meta-transitions are likewise reported by typically measured field dependencies of entropy and further of heat capacity that reveals a breakdown of temperature-energy dependence during meta-transitions. The temperature-energy dependence breakdown vanishing reported for high temperature emphasizes the metamagnetoelectric state death beyond relatively low-temperature values. Furthermore, large temperature-fields dependencies are noticed except for critical values where meta-transitions are occurring in the investigated A2Cu2Mo3O12 compounds.

A New Strategy for Optimizing HSIL Transmission Lines

This paper presents an efficient procedure for optimizing the electric field at ground level of high surge impedance loading transmission lines. Such lines have the capacity to achieve higher power transmission rates than the conventional ones. The ellipsoidal method is applied in order to maximize the transmitted power and minimize the electric field at ground level through the variation of the conductor’s positions in the tower, given its physical and electrical constraints. By means of an efficient new approach to handle the conductors, the optimization gives birth to compact line designs combined with conventional bundles of conductors. Furthermore, it is shown that the proposed strategy can increase the transmitted power, reduce the electric field at ground level, and shorten the running time of the optimization algorithm.

Power Take-Off and Energy Storage System Static Modeling and Sizing for Direct Drive Wave Energy Converter to Support Ocean Sensing Applications

This paper addresses the sizing and design problem of a permanent magnet electrical machine power take-off system for a two-body wave energy converter, which is designed to support ocean sensing applications with sustained power. The design is based upon ground truth ocean data bi-spectrums (swell and wind waves) from Martha’s Vineyard Coastal Observatory in the year 2015. According to the ground truth ocean data, the paper presents the optimal harvesting power time series of the whole year. The electrical machine and energy storage static modeling are introduced in the paper. The paper uses the ground truth ocean data in March to discuss the model integration of the buoy dynamic model, the power take-off model, and the energy storage model. Electrical machine operation constraints are applied to ensure the designed machine can fulfill the buoy control requirements. The electrical machine and energy storage systems operation status is presented as well. Furthermore, rule-based control strategies are applied to the electrical machine for fulfilling specific design demands, such as improving power generating efficiency and downsizing the electrical machine scale. The corresponding required capacities of the energy storage system are discussed. This paper relates results to the wave data sets (different combinations of significant wave heights and periods of both swell and wind waves). In this way, the power take-off system rule-based control strategy determinations can rely on current ocean wave measurements instead of a large historical ocean wave database.

Power and Transport Nexus: Routing Electric Vehicles to Promote Renewable Power Integration

Increasing plug-in electric vehicle (PEV) charging stations are coupling the power and transportation systems tightly together. The distribution of PEV traffic flows will be constrained by and inversely affect both systems. In this paper, we study the PEV routing problem on a coupled transportation and power network from the perspective of a social coordinator. We formulate an interdisciplinary second order cone programming model that optimizes PEVs' driving paths and charging locations to minimize the system's social costs, which include driving and charging time costs of PEV drivers and power supply costs. The model employs: 1) an expanded transportation network model to explicitly describe PEVs' driving range constraints on the transportation network; 2) the AC power flow model to describe the electrical constraints of the power system. We then design an iterative column generation algorithm to efficiently solve it. We validate the proposed method on a coupled transportation and power network with distributed renewable generation. Numerical simulation results show that routing PEV traffic flows adopting the proposed strategy can effectively improve social welfare and promote renewable generation integration.

Well-posedness theory for electromagnetic obstacle problems

This paper develops a well-posedness theory for hyperbolic Maxwell obstacle problems generalizing the result by Duvaut and Lions (1976) [5]. Building on the recently developed result by Yousept (2020) [30], we prove an existence result and study the uniqueness through a local H(curl)-regularity analysis with respect to the constraint set. More precisely, every solution is shown to locally satisfy the Maxwell-Ampère equation (resp. Faraday equation) in the region where no obstacle is applied to the electric field (resp. magnetic field). By this property, along with a structural assumption on the feasible set, we are able to localize the obstacle problem to the underlying constraint regions. In particular, the resulting localized problem does not employ the electric test function (resp. magnetic test function) in the area where the L2-regularity of the rotation of the electric field (resp. magnetic field) is not a priori guaranteed. This localization strategy is the main ingredient for our uniqueness proof. After establishing the well-posedness, we consider the case where the electric permittivity is negligibly small in the electric constraint region and investigate the corresponding eddy current obstacle problem. Invoking the localization strategy, we derive an existence result under an L2-boundedness assumption for the electric constraint region along with a compatibility assumption on the initial data. The developed theoretical results find applications in electromagnetic shielding.

Harmonic Currents Injection Strategy With Optimal Air Gap Flux Distribution for Multiphase Induction Machine

The proposed technique focuses on the nonsinusoidal power supply control strategy aiming to obtain the optimal air gap flux density distribution. The electrical constraints for the alignment between rotated fundamental and harmonic air gap flux are illustrated in detail. The supporting simulation is performed to analyze the misaligned angles between fundamental and harmonic air gap flux for the traditional methods. Different from traditional flux-oriented methods, the improved algorithm for harmonic currents injection is designed based on rotor flux orientated control in fundamental plane and air gap flux orientated control in harmonic planes. The synchronous and aligned control of the fundamental and harmonic air gap flux is achieved regardless of load condition. The experimental verification is implemented based on a multiphase driving platform using a seven-phase induction machine as prototype. Various scenarios are provided for the proposed control strategy comparing with the traditional ones in terms of induced electromotive force waveforms, harmonic currents, and advance angles of air gap flux. The simulated and experimental results validate the theoretical assumption and the effectiveness of the proposed method.

Electro-Thermal Codesign Methodology of an On-Board Electric Vehicle Charger

Abstract Significant advances are needed to optimize the charging speed, reliability, safety, and cost of today's conservatively designed electric vehicle (EV) charging systems. The design and optimization of these novel engineering systems require concurrent consideration of thermal and electrical phenomena, as well as component and system level dynamics and control to guarantee reliable continuous operation, scalability, and minimum footprint. This work addresses the concurrent thermal and electrical design constraints in a high-density, on-board, bidirectional charger with vehicle-to-grid (V2G), grid-to-vehicle (G2V), vehicle-to-house (V2H), and vehicle-to-vehicle (V2V) power transfer capabilities. The electrical design of this charger consists of DC–DC and DC–AC power stages connected in series. The power-stage circuits are implemented on a printed circuit board (PCB) with 16 surface-mount silicon carbide MOSFETs, three inductors, and one transformer. The main goal of this work is to investigate the interplay between the cooling architecture and the PCB layout, and the corresponding impact on the heat dissipation and parasitic inductance. This work compares the performance of three generations of this multifunctional charger that employ different design methodologies and proposes high-level design guidelines derived from multiphysics simulations and experimental tests.

Design and implementation of dielectric windows for detection of radial deformation of HV transformer winding using radar imaging

The synthetic aperture radar (SAR) imaging method has been recently proposed for online radial deformation detection of high voltage transformer windings. In this method, electromagnetic waves should be transmitted toward the transformer windings through an antenna. The antenna should be moved along the height of the transformer. Since electromagnetic waves cannot penetrate the metal tank, a window is required on the body of the transformer tank to transmit waves toward the winding. The proper design of such a window and investigation of SAR imaging methods with the existence of it, is necessary to make the previous SAR imaging studies applicable to the transformer winding. Therefore, in order to study the design and implementation of a dielectric window, a prototype of a tank with a dielectric window is built considering electrical and mechanical constraints. The experimental results show the feasibility of applying the SAR imaging for localisation of radial deformation with the existence of a dielectric window in real transformers.

An At-Scale Tailless Flapping-Wing Hummingbird Robot. I. Design, Optimization, and Experimental Validation

Designing a hummingbird-inspired, at-scale, tail-less flapping-wing micro aerial vehicle (FWMAV) is a challenging task in order to achieve animallike flight performance under the constraints of size, weight, power, and actuation limitations. It is even more challenging to design such a vehicle with a pair of independently controlled wings equipped with a total of only two actuators. This article details a systematic solution for the design optimization and prototyping of such FWMAVs. The proposed solution covers the complete system models and analysis of wing-actuation dynamics, control authorities, body dynamics, mechanical limitations, and electrical constraints. Each subsystem, as well as the overall system, is experimentally validated. This comprehensive approach can facilitate the design of such FWMAVs with different optimization goals. To demonstrate the effectiveness of the proposed approach, in this article, we conduct three different design optimization tasks, which yield three different prototype systems: optimizing the lift-to-weight ratio, optimizing control bandwidth, and optimizing control authority. We first construct a vehicle with an optimized lift-to-weight ratio. Based on it, the other two platforms with different design optimization goals are presented for better flight performance. Flight tests were performed on each prototype to validate their flight performance and design goals. Compared to optimized control bandwidth, we demonstrate that the vehicle with optimized control authorities is significantly more capable in terms of flight performance. It shows sustained stable flight in both hovering and heavy load carrying (more than 60% of the vehicle's total weight), which is hard for the other two platforms to achieve.

Optimal planning and operation of multi-carrier networked microgrids considering multi-energy hubs in distribution networks

In this paper, we propose a new scheme for designing multi-carrier networked microgrids. Various multi-energy carriers are utilized to form energy hubs which exchange energy with each other and the main electricity and gas networks. The proposed model considers renewable generation, diesel generators, fuel cells, energy storages, combined heat and powers, boilers, combined cooling heat and powers, and power to gas converters. The seasonal load patterns are considered to design the optimal capacity of combined cooling, heating, and powers. The main objective of the proposed model is to operate the integrated hubs with minimum cost, meet the consumer’s required energies, reduce the emissions, and create a bi-directional interaction between electricity, and gas networks using power to gas converters. While all electrical, mechanical, and technical constraints are satisfied. To achieve these improvements, industrial and residential hubs interact with other multi-carrier microgrids to determine the optimal operation of hubs. The proposed model is tested on a standard case study and results show when hubs integrate about the total daily cost of each microgrid has been improved about 200 $. Besides, the thermal energy not supply in microgrid 4 has been improved from 4.61 MWh to 0.45 MWh.

Crisscross optimization based short-term hydrothermal generation scheduling with cascaded reservoirs

Short-term hydrothermal generation scheduling (SHGS) considering various hydraulic and electric constraints is a complex non-convex optimization problem. The coupling connection of cascaded reservoirs and the valve-point effects of thermal units greatly increase the difficulty of finding optimal solution. This paper presents an efficient solution to the SHGS problem by using a novel crisscross optimization (CSO) algorithm, which generates the optimal scheduling results by applying two distinctive search operators, i.e., horizontal crossover and vertical crossover. The horizontal crossover is used as a global optimizer that can reduce the search blind spots in complex solution space through a cross-border search strategy. The vertical crossover is used to address the premature convergence problem by applying a unique dimensional crossover mechanism. Both search operators take turns to generate moderation solutions and CSO always maintains a population of historically best solutions by using a greedy strategy so as to speed up the convergence speed. To investigate the CSO’s performance on the SHGS problem, three test systems widely adopted in the literature are used to do the short-term hydrothermal generation scheduling. The results reveal that the proposed algorithm has good robustness and outperforms other state-of-the-art methods in terms of solution quality.

Impact of Electrical Stress and Neutron Irradiation on Reliability of Silicon Carbide Power MOSFET

The combined effects of electrical stress and neutron irradiation of the last generation of commercial discrete silicon carbide power MOSFETs are studied. The single-event burnout (SEB) sensitivity during neutron irradiation is analyzed for unstressed and electrically stressed devices. For surviving devices, a comprehensive study of the breakdown voltage degradation is performed by coupling the electrical stress and irradiation effects. In addition, mutual influences between electrical stress and radiative constraints are investigated through TCAD modeling.

Optimization of an On-Grid Inverter for PV Applications Using Genetic Algorithms

A new approach to the optimal design of power inverters for on-grid photovoltaic systems that uses genetic algorithms (GA) is provided in this article. The nonlinear average model is adopted to model the conversion stage in order to accurately evaluate and quickly estimate the power losses of the power devices. The hysteresis current control that guarantees a quasi-sinusoidal output current is applied to generate the inverter control signals. The design of the solar inverter must meet three contradictory objectives that need to be optimized at the same time. In fact, the aim is to maximize the efficiency of the converter while minimizing its size and price under electrical constraints. The problem variables are the output current ripple and the passive and active components available on the market (IGBTs/MOSFETs, Diodes, Inductors). NSGA-II (Elitist Nondominated Sorting Genetic Algorithm) is appropriate in the case where discrete design variables are used to search for optimal Pareto solutions. It carries out a systematic and efficient search among the developed databases for a set of components which define the optimal structures of the inverter. The introduced method makes the design task easier since the best solutions depend on the components available on the market and significantly reduces the time to market for manufacturers.

Comprehensive Finite Element Modeling for Pulsed Magnet Design Using COMSOL and Java

Ultra-high field pulsed magnets must simultaneously satisfy a number of often competing electrical, electromagnetic, structural, thermal, and economic constraints. To produce the highest field possible, nondestructive pulsed magnets are designed to operate at the limits of mechanical strength and electrical capacity of conductors. In this presentation, we will introduce a coupled multi-engineering finite element method (FEM) implemented in COMSOL Multiphysics package for detailed and accurate calculations of the mechanical, thermal and electromagnetic performances in entire longitudinal cross-section of the pulsed magnet. These transient FEM simulations are performed for entire pulse length and take into account the temperature and magnetic field dependences of electrical conductivity and mechanical properties of all the materials to provide better accuracy. Application Programming Interface (API) feature of COMSOL was used to automate repetitive modeling steps to significantly reduce the necessary time to create FEM models for a pulsed magnet which may consists up to thousands of turns and insulation/reinforcement layers. Computational results for our signature 100T non-destructive pulsed magnet will be presented.

Impact of pulsed electric fields and mechanical compressions on the permeability and structure of Chlamydomonas reinhardtii cells

Current research findings clearly reveal the role of the microalga’s cell wall as a key obstacle to an efficient and optimal compound extraction. Such extraction process is therefore closely related to the microalga species used. Effects of electrical or mechanical constraints on C. reinhardtii’s structure and particularly its cell wall and membrane, is therefore investigated in this paper using a combination of microscopic tools. Membrane pores with a radius between 0.77 and 1.59 nm were determined for both reversible (5 kV∙cm−1) and irreversible (7 kV∙cm−1) electroporation with a 5 µs pulse duration. Irreversible electroporation with longer pulses (10 µs) lead to the entry of large molecules (at least 5.11 nm). Additionally, for the first time, the effect of pulsed electric fields on the cell wall was observed. The combined electrical and mechanical treatment showed a significant impact on the cell wall structure as observed under Transmission Electron Microscopy. This treatment permits the penetration of larger molecules (at least 5.11 nm) within the cell, shown by tracking the penetration of dextran molecules. For the first time, the size of pores on the cell membrane and the structural changes on the microalgae cell wall induced by electrical and mechanical treatments is reported.

The Short-Term Economical Operation Problem for Hydropower Station Using Chaotic Normal Cloud Model Based Discrete Shuffled Frog Leaping Algorithm

The short-term economical operation (STEO) in hydropower station is nonlinear mixed integer problem, satisfying complex hydrologic constraints simultaneously. In this paper, we decomposed STEO into unit commitment (UC) and economical load dispatch (ELD) sub-problems. In terms of premature convergence and inefficient search performance of conventional shuffled frog leaping algorithm (SFLA), we proposed chaotic normal cloud model based discrete SFLA (CNCM-DSFLA). The CNCM-DSFLA incorporates novel population initialization based on renewed chaotic logistic mapping, three frog sub-populations including leader frog, follower frog and mutation frog, heuristic frog activation mechanism and frog mutation based on normal cloud model. The CNCM-DSFLA is applied to solve UC sub-problem and ELD sub-problem is handled based on optimal economic load distribution table. Moreover, reserve capacity supplement and repair, and minimum startup and shutdown repair strategies are introduced to deal with multiple hydrologic and electrical constraints. Finally, CNCM-DSFLA is verified by a case in Three Gorges hydropower station. Simulation results demonstrate that CNCM-DSFLA gets higher-quality solutions with less total water consumption and shorter computation time in comparison with other methods. Thus, validity and superiority of CNCM-DSFLA are verified and it can provide novel effective way for solving STEO problem in complex hydropower station system.

Optimal design of a 314kW-class IPMSM for railway vehicles using hydrogen fuel cells

Conventional diesel railway vehicles produce many air pollutants. In order to solve this problem, railway vehicles using eco-friendly hydrogen fuel cells are emerging. The main difference from the conventional traction motor is that it does not control the phase back electromotive force (phase-BEMF) separately at the maximum speed. Because of this, it should reduce the use of permanent magnets yet increase their size due to necessary high current. This paper performs the interior permanent magnet synchronous motor (IPMSM) design to meet the harsh electrical and mechanical constraints. Although the basic design is carried out to satisfy the design constraints, structural problems occur. These are resolved through the optimization process to attain the optimal design of a 314kW-class IPMSM for railway vehicles using hydrogen fuel cells.