Showing papers on "Electrical network published in 2019"
TL;DR: A formulation and solution procedure for stochastic optimal reactive power dispatch (ORPD) problem with uncertainties in load demand, wind and solar power, and the effectiveness of a proper constraint handling technique is substantiated.
125 citations
TL;DR: Three cases are presented to demonstrate the effectiveness of the planning and design method and to show the influence of the nodal energy prices on the IDR program as well as the penetration of solar energy based on a reconstructive MES in northern China.
74 citations
TL;DR: A novel parameter identification method and its implementation on SOP prediction for lithium-ion batteries is proposed and the extremum seeking algorithm is developed for identifying the parameters of batteries on the basis of an electrical circuit model incorporating hysteresis effect.
Abstract: Accurate state-of-power (SOP) estimation is critical for building battery systems with optimized performance and longer life in electric vehicles and hybrid electric vehicles. This paper proposes a novel parameter identification method and its implementation on SOP prediction for lithium-ion batteries. The extremum seeking algorithm is developed for identifying the parameters of batteries on the basis of an electrical circuit model incorporating hysteresis effect. A rigorous convergence proof of the estimation algorithm is provided. In addition, based on the electrical circuit model with the identified parameters, a battery SOP prediction algorithm is derived, which considers both the voltage and current limitations of the battery. Simulation results for lithium-ion batteries based on real test data from urban dynamometer driving schedule (UDDS) are provided to validate the proposed parameter identification and SOP prediction methods. The proposed method is suitable for real operation of embedded battery management system due to its low complexity and numerical stability.
71 citations
TL;DR: A multi-objective optimization problem to obtain the simultaneous placement and sizing of F CSs and distributed generations (DGs) with the constraints such as the number of EVs in all zones and possible number of FCSs based on the road and electrical network in the proposed system is presented.
Abstract: The large-scale construction of fast charging stations (FCSs) for electrical vehicles (EVs) is helpful in promoting the EV. It creates a significant challenge for the distribution system operator to determine the optimal planning, especially the siting and sizing of FCSs in the electrical distribution system. Inappropriate planning of fast EV charging stations (EVCSs) cause a negative impact on the distribution system. This paper presented a multi-objective optimization problem to obtain the simultaneous placement and sizing of FCSs and distributed generations (DGs) with the constraints such as the number of EVs in all zones and possible number of FCSs based on the road and electrical network in the proposed system. The problem is formulated as a mixed integer non-linear problem (MINLP) to optimize the loss of EV user, network power loss (NPL), FCS development cost and improve the voltage profile of the electrical distribution system. Non-dominated sorting genetic algorithm II (NSGA-II) is used for solving the MINLP. The performance of the proposed technique is evaluated by the 118-bus electrical distribution system.
62 citations
TL;DR: A simple yet effective variable electrical network (VEN) condition monitoring method for dc-link capacitors in three-phase pulsewidth modulation (PWM) ac–dc–ac power converters and results prove the method to be effective and accurate.
Abstract: The dc-link capacitors are important components that tend to be one of the weakest part of power converters. Thus, it is necessary to monitor the aging parameters of dc-link capacitors in valuable power electronic systems. This paper proposes a simple yet effective variable electrical network (VEN) condition monitoring method for dc-link capacitors in three-phase pulsewidth modulation (PWM) ac–dc–ac power converters. The capacitance ( C ) and equivalent series resistance of dc-link capacitors are estimated through the designed VEN unit during the discharging process. This VEN method does not need the current sensor or injecting signals into the control loop. The above property is favorable for the hardware and controller design. Besides, the designed monitoring circuit can be an external unit or a built-in unit which offers a flexible solution for electrical devices. When the designed VEN is used as an external unit, neither the hardware design nor the programs in the controller needs to change, which is practical and economic for electrical devices in use. Experiments are carried out in a 55 kW ac–dc–ac inverter with different capacitors. The experiment results prove the method to be effective and accurate.
61 citations
01 Jan 2019
TL;DR: A circuit of an optoelectronic contactless voltage relay that provides a high degree of reliability and the possibility of controlling the operating modes of various installations for amplifying electrical signals using optothyristors is presented.
Abstract: Based on the results of the analysis of resistive circuits, a new circuit of an optoelectronic contactless voltage relay is developed in the article and its application in the power supply system is considered. The possibility of controlling the operating modes of various installations for amplifying electrical signals using optothyristors is presented and methods for their inclusion in electrical circuits are given. Optoelectronic contactless voltage relays were tested under laboratory conditions to obtain input-output characteristics and capacitance voltage waveforms. Based on the improvement of the proposed circuit, a circuit of an optoelectronic contactless voltage relay is developed and provides a high degree of reliability. The proposed voltage relay circuit is simulated using the Electronics Workbench and MATLAB R2014a programs, the results of which show that the changes in the shape of the output voltage curve are close to a sinusoid and coincide with the results obtained analytically.
50 citations
TL;DR: In this paper, an experimentally validated 1D electrochemical-thermal model of a large format 53 Ah pouch cell is employed to underpin the performance evaluation of parallel connected cells within the context of a complete ESS.
Abstract: Variation in energy capacity and resistance of cells connected in parallel can degrade the overall performance of the energy storage system (ESS). Such variations can lead to significant individual differences in battery load current, state of charge (SOC) and heat generation. An experimentally validated 1D electrochemical-thermal model of a large format 53 Ah pouch cell is employed to underpin the performance evaluation of parallel connected cells within the context of a complete ESS. The cell model, developed within COMSOL Multiphysics is coupled with an electrical circuit model of the ESS within Matlab. Results are presented that quantify cell-to-cell differences in load current and heat generation as the length of the parallel connection and value of the cell interconnection resistance is varied. The results highlight that variations in cell depth of discharge and the occurrence of temperature gradients across the parallel connection increases at higher load currents and interconnect resistances. The impact is amplified as the length of the parallel connection increases which will accelerate cell ageing and, if unmanaged, may present safety concerns.
43 citations
TL;DR: In this paper, an electro-analog model of fractional diffusion process which enables to simulate heat dissipation in circuit board has been proposed and analyzed through the exponential and Mittage Leffler kernel of non-integer order differentiations.
Abstract: The new idea of Atangana and Baleanu introduced recently for fractional derivatives has received tremendous attention from researchers of various fields. However, this idea has not been applied for heat dissipation in transmission line of electrical circuit. Although the phenomenon of heat dissipation potentially damages the electrical devices which leads to catastrophic failure and shortens the life expectancy of costly electrical components. This manuscript signifies an electro-analog model of fractional diffusion process which enables to simulate heat dissipation in circuit board. The modeling of the problem has been established through modern operators of fractional calculus via the governing differential equation. By invoking Laplace transform on fractional governing equation of heat dissipation in transmission line of circuit, the analytic solutions are investigated through the exponential and Mittage Leffler kernel of non-integer order differentiations. The duality of analytic solutions has been compared with Caputo–Fabrizio and Atangana–Baleanu fractional differentiations graphically using embedded pertinent parameters. The comparison of both approaches of fractional differentiations has disclosed the heat transfer of circuit board and diffusion process with dissipation vividly.
42 citations
TL;DR: The proportional-integral passivity-based control (PI-PBC) is chosen to control the direct power model of the VSC-HVDC system since this system exhibits a port-Hamiltonian formulation in open-loop and as PI-P BC can exploit this formulation to design a PI controller, which guarantees asymptotically stable in closed-loop based on Lyapunov’s theory.
36 citations
TL;DR: In this article, the analytical solutions for the RL, LC, RC, RC and RLC electrical circuits described by the left generalized fractional derivative operator and the Caputo left generalized derivative operator were presented.
Abstract: The paper addresses the analytical solutions for the RL, LC, RC and RLC electrical circuits described by the left generalized fractional derivative operator and the Caputo left generalized fractional derivative. The $ \rho$
-Laplace transform introduced by Fahd and Thabet was used to obtain the analytical solutions of the electrical circuit equations described by certain generalized fractional derivative operators. Finally, we present some numerical simulations of the analytical solutions of the RL, LC, RC and RLC electrical circuit equations described by certain generalized fractional derivatives.
34 citations
TL;DR: A system-wide coordinated operation method for MEMGs is proposed to dispatch different components including generation resources and flexible loads to simultaneously supply electricity and thermal energy to customers for higher energy utilisation efficiency.
Abstract: A multi-energy microgrid (MEMG) aims to simultaneously supply electricity and thermal energy to customers for higher energy utilisation efficiency. In this study, a system-wide coordinated operation method for MEMGs is proposed to dispatch different components including generation resources and flexible loads. In the coordination method, the coupling constraints of electrical and heat network, dynamic characteristics of heat network as well as the power flow constraints are comprehensively modelled. Besides, the price-based demand response and indoor temperature control strategy are used as demand response for more flexible operation of the combine electrical and thermal networks. The coordination model is formulated as a mixed-integer linear programming problem and tested on 33-bus and 69-bus MEMGs. Simulation results verify the advantages of the proposed method over existing methods.
TL;DR: In this paper, a theoretical method to characterize the stationary stochastic dynamic responses and the energy harvesting performance under white noise accelerations was proposed, and the theoretical predictions were compared with numerical simulations and experimental results to validate the effectiveness of the proposed theoretical method.
TL;DR: Experimental results show that the method proposed can detect arcing faults efficiently, avoiding false tripping, whilst taking into account a high degree of diagnosis accuracy and average detection time.
TL;DR: This paper uses a global parameter optimization method PSADE to speed up evolutionary convergence, and uses the proposed algorithm (both single- and multi-objective) to successfully evolve passive, active, and BiCMOS circuits.
TL;DR: In this paper, conditions determining the rank of the so-called compound nodal admittance matrix and its diagonal subblocks are deduced from the characteristics of the electrical components and the network graph.
Abstract: Most techniques for power system analysis model the grid by exact electrical circuits. For instance, in power flow study, state estimation, and voltage stability assessment, the use of admittance parameters (i.e., the nodal admittance matrix) and hybrid parameters is common. Moreover, network reduction techniques (e.g., Kron reduction) are often applied to decrease the size of large grid models (i.e., with hundreds or thousands of state variables), thereby alleviating the computational burden. However, researchers normally disregard the fact that the applicability of these methods is not generally guaranteed. In reality, the nodal admittance must satisfy certain properties in order for hybrid parameters to exist and Kron reduction to be feasible. Recently, this problem was solved for particular cases of monophase and balanced triphase grids. This paper investigates the general case of unbalanced polyphase grids. First, conditions determining the rank of the so-called compound nodal admittance matrix and its diagonal subblocks are deduced from the characteristics of the electrical components and the network graph. Second, the implications of these findings concerning the feasibility of Kron reduction and the existence of hybrid parameters are discussed. In this regard, this paper provides a rigorous theoretical foundation for various applications in power system analysis.
TL;DR: Taking the minimum takeoff gross weight as the objective, the Lagrange multiplier method directly solves this nonlinear optimization of ECS and offers the optimal structural and operating parameters of the system.
Abstract: Optimization of refrigeration system for aircraft environmental control system (ECS) benefits the whole aircraft performance significantly. However, due to the complex dehumidification process, the heat transfer and heat-work conversion processes in the system, numerous intermediate variables in the system model aggravate the nonlinear and multivariate properties of the governing equations. Taking the typical two-wheel high-pressure de-water ECS as an example, this contribution introduces the heat current method to model the refrigeration system, which reveals the system topology and heat transfer and heat-work conversion characteristics simultaneously. Analogous to electrical circuit, the governing equations of whole system are obtained according to the circuit principle. Furthermore, a comparison is conducted to clarify the differences between the traditional energy flow method based on Sankey diagram and the heat current method. Next, taking the minimum takeoff gross weight as the objective, using the Lagrange multiplier method directly solves this nonlinear optimization and offers the optimal structural and operating parameters of the system. The optimized results show that the cruise flight hour has little impact on the optimal design variables, while the cabin heat load has an approximately linear relationship with the optimal design variables. Finally, when only the cabin temperature changes, the node temperatures are almost constant, which can be taken as a criterion for the design of each component.
TL;DR: This paper focuses onRL line models and proposes two approximate KR algorithms producing reduced lines with the first-order transfer functions and capable of representing exactly the asymptotic behavior of electric signals, even if they are unbalanced.
Abstract: Kron reduction (KR) is a methodology for analyzing an electrical network by replacing it with a simpler circuit having less nodes but the same terminal behavior of voltages and currents at target vertices. Existing approaches to instantaneous KR, however, can fail in preserving the structure of transfer functions representing power lines. Therefore, even if the original lines are passive $RLC$ circuits, reduced lines might have transfer functions that do not correspond to a physically realizable passive system. To overcome this drawback, in this paper we focus on $RL$ line models and propose two approximate KR algorithms producing reduced lines with the first-order transfer functions and capable of representing exactly the asymptotic behavior of electric signals, even if they are unbalanced. Then, we show how to apply these KR methods to the design of decentralized voltage and frequency controllers for AC islanded microgrids. Notably, we focus on the plug-and-play algorithm previously proposed by some of the authors, which assumes loads connected to the inverter outputs, and generalize it to networks where loads appear in arbitrary positions. Theoretical results are validated with numerical examples and the application of KR for designing PnP controllers is assessed through a simulation on a 21-bus microgrid.
TL;DR: A Multiobjective Ant Lion algorithm (MOALO) is proposed to find the Pareto optimal front for the multiobjective OPF problem by optimizing 4-conflicting objective functions simultaneously.
Abstract: In this study, a multiobjective optimization is applied to Optimal Power Flow Problem (OPF). To effectively achieve this goal, a Multiobjective Ant Lion algorithm (MOALO) is proposed to find the Pareto optimal front for the multiobjective OPF. The aim of this work is to reach good solutions of Active and Reactive OPF problem by optimizing 4-conflicting objective functions simultaneously. Here are generation cost, environmental pollution emission, active power losses, and voltage deviation. The performance of the proposed MOALO algorithm has been tested on various electrical power systems with different sizes such as IEEE 30-bus, IEEE 57-bus, IEEE 118-bus, IEEE 300-bus systems and on practical Algerian DZ114-bus system. The results of the tests proved the versatility of the algorithm when applied to large systems. The effectiveness of the proposed method has been confirmed by comparing the results obtained with those obtained by other algorithms given in the literature for the same test systems.
TL;DR: This work shows experimentally how electrical energy can be harvested directly from cell membrane potential and used to power a wireless communication, including wireless communication of sensed biological quantities to a remote receiving hub.
TL;DR: This paper seeks to provide a novel method to solve gas flow equations through a network under steady-state conditions by reformulated into non-linear matrix equations, and compared to the outputs of two numerical methods.
Abstract: The continuous uninterrupted supply of Natural Gas (NG) is crucial to today’s economy, with issues in key infrastructure, e.g., Baumgarten hub in Austria in 2017, highlighting the importance of the NG infrastructure for the supply of primary energy. The balancing of gas supply from a wide range of sources with various end users can be challenging due to the unique and different behaviours of the end users, which in some cases span across a continent. Further complicating the management of the NG network is its role in supporting the electrical network. The fast response times of NG power plants and the potential to store energy in the network play a key role in adding flexibility across other energy systems. Traditionally, modelling the NG network relies on nonlinear pipe flow equations that incorporate the demand (load), flow rate, and physical network parameters including topography and NG properties. It is crucial that the simulations produce accurate results quickly. This paper seeks to provide a novel method to solve gas flow equations through a network under steady-state conditions. Firstly, the model is reformulated into non-linear matrix equations, then the equations separated into their linear and nonlinear components, and thirdly, the non-linear system is solved approximately by providing a linear system with similar solutions to the non-linear one. The non-linear equations of the NG transport system include the main variables and characteristics of a gas network, focusing on pressure drop in the gas network. Two simplified models, both of the Irish gas network (1. A gas network with 13 nodes, 2. A gas network with 109 nodes) are used as a case study for comparison of the solutions. Results are generated by using the novel method, and they are compared to the outputs of two numerical methods, the Newton–Raphson solution using MATLAB and SAINT, a commercial software that is used for the simulation of the gas network and electrical grids.
TL;DR: In this paper, the authors present the development of a numerical and a simplified analytical model to determine the internal resistance (Rint) and predict the open circuit voltage, charge voltage, current and power values of TEGs.
Abstract: The conversion of residual thermal energy into electricity using TEGs (Thermoelectric Generators) arises as a promising technological alternative for increasing energy efficiency and power generation. In order to optimize the performance of TEGs, it is known that the maximum output power is obtained by matching the impedances between the TEG and the connected load. Therefore, the objective of this work is to present the development of a numerical and a simplified analytical model to determine the internal resistance (Rint) and predict the open circuit voltage, charge voltage, current and power values of TEGs. The models have used as reference the thermoelectric module TEHP 1263-1.5 (Thermonamic), with the analytical one being based on the classical theory of electrical circuit analysis and, for the numerical one, a three-dimensional geometric model was developed and the set of equations were solved in the COMSOL Multiphysics® tool by the finite element method. The Rint obtained by the analytical and numerical models were, respectively, 3.157 Ω and 6.027 Ω, and the value supplied by the supplier is 3.154 Ω. Therefore, the analytical model is indicated as a reference to estimate Rint of the TEG, allowing optimizing its use by choosing the load resistance that will result in the maximum power.
TL;DR: DPsim is a real-time capable solver for power systems that operates in the dynamic phasor and electromagnetic transient (EMT) domain and it is closely integrated with the VILLASframework to support a wide range of interfaces for co-simulation.
TL;DR: Fractional-order lumped-element equations for capacitors, inductors and resistors, as well as Kirchhoff's voltage and current laws are derived using quasi-static approximations of fractional- order Maxwell’s equations.
TL;DR: The proposed research paper proposes and investigates an intelligent hybrid implementation of electrical network driven by a five layer ANFIS moduledriven by a set of FIS rule base driven by an elaborate mathematical modeling to arrive at the design electrical equations.
Abstract: Power quality is an essential parameter in delivery of electrical power through the distributions networks in real time. Power transmission quality is affected by several factors which include frequently occurring voltage variations in the form of swells and sags, harmonic distortions, voltage and noise spikes. They severely degrade the quality of power delivered if unattended and directly have a consequence on the energy consumption which in turn increases the system cost and efficiency. The proposed research paper proposes and investigates an intelligent hybrid implementation of electrical network driven by a five layer ANFIS module driven by a set of FIS rule base. The proposed model has been tested after an elaborate mathematical modeling to arrive at the design electrical equations which are exported on to the ANFIS for training and validation. The proposed technique has been compared against existing ANN and Fuzzy algorithms and superior performance with respect to stability, settling time, reduction in noise have been observed in the experimentation. Faster convergence towards optimal power flow is achieved using the ANFIS model.
TL;DR: In this article, the authors developed a fully three-dimensional strongly coupled multiphysics model for flow-driven energy harvesting, which was applied to establish a mixed integral equation describing the incompressible Newtonian flow, elastic substrate structure, piezoelectric patch, equipotential electrode and attached electric circuit.
01 Sep 2019
TL;DR: A method of samples of instantaneous currents and voltages is proposed, which allows to extract only sinusoidal information necessary for correct operation of digital relay protection and automation from information containing instantaneous values of currents containing periodic and aperiodic components.
Abstract: In this paper, a method of samples of instantaneous currents and voltages is proposed, which allows to extract only sinusoidal information necessary for correct operation of digital relay protection and automation from information containing instantaneous values of currents containing periodic and aperiodic components. The studies were performed based on the analysis of the equations of short-circuit currents in electrical networks. The time during which the current and voltage parameters are sampled does not exceed 2 milliseconds, which is less than 1/8 of the industrial frequency period. The method made it possible to implement protections, which fix damage with a help of analog devices only for several periods of current change. At the same time, the protections implemented by analog devices are not free from errors introduced by aperiodic components. Principles for the implementation of directional protection of generators and transformers are proposed. Directional protection of generators and transformers is feasible in the presence of information about the modes of the electrical network elements that are connected with the protected ones. The proposed four-sampling method allows to implement all protections that react to periodic components of currents and voltages using only four instantaneous values of currents and voltages obtained within two milliseconds or less after the occurrence of a short circuit.
TL;DR: A type of port-Hamiltonian system is studied, in which the controller or disturbance is not applied to the flow variables, but to the systems power, a scenario that appears in many practical applications and a stability analysis is carried out.
TL;DR: The classical Cayley–Hamilton theorem is extended to different orders fractional continuous-time linear systems and to fractional electrical circuits.
Abstract: The classical Cayley–Hamilton theorem is extended to different orders fractional continuous-time linear systems and to fractional electrical circuits.
TL;DR: An optimal control formulation to tackle the real-time control of plasma position, shape and current in a tokamak is introduced and the main ingredients for finding numerical solutions are presented: the finite element discretization, accurate linearizations and Sequential Quadratic Programming.
TL;DR: In this paper, an equivalent electrical circuit with mixed kinetic and charge transfer is applied to analyze the impedance of the experimental data of the interface and a second model calculation based on an artificial neural network (ANN) for predicting the electrochemical properties of the same interface.
Abstract: Electrochemical impedance spectroscopy (EIS) is commonly used in studying solid–liquid interfacial properties. In this work, the electrochemical behavior of potential-induced defects in self-assembled CH3(CH2)3SH monolayer (SAM) electrodeposited on the surface of a mono-crystalline gold rod has been experimentally investigated and theoretically modeled. An equivalent electrical circuit with mixed kinetic and charge transfer is applied to analyze the impedance of the experimental data of the interface. The results are compared to those obtained with a second model calculation based on an artificial neural network (ANN) for predicting the electrochemical properties of the same interface. The proposed approach defines the equivalent circuit elements for the interface under study. The latter is based on adjusting the electrical parameters by using a detailed methodology proposed to build up the equivalent circuit. We illustrated the experimental and predicted numerical simulation of the corresponding model. Numerical simulation of the neural network model shows the impact of using equivalent circuits to describe the features of the materials under study. The results demonstrate a high performance in predicting and optimizing the equivalent circuit. The advantage of our adopted model appears by comparing our model results and experimental data analysis.