Electrical Network Simulation Research Articles

Evaluation of Sinusoidal Distribution Networks Using the EPC Simulation Software

The electric power calculator (EPC) software, for the simulation and analysis of electrical networks at the industrial frequency, is described in this article, including its source code and operational diagram. Compared to well-known commercial software, EPC directly provides the values of the voltages, currents, and powers in each subsystem. The voltages and currents are calculated, in phasor notation, applying Kirchhoff’s laws, while the powers are obtained through the components of the apparent power vector. In this paper, the EPC software could be applied to three-phase networks made up of a distribution transformer and two three-phase wye-configured loads. The correctness of the results of the EPC software was verified by comparison with those obtained using the Multisim commercial software and with the measurements recorded by the Fluke 435 analyzer in a real distribution network of residential buildings. The values of the voltages and currents provided by the EPC were the same as those measured by the Fluke, and the differences observed using Multisim were less than 0.6%. Consequently, the EPC software is an excellent complement for power analyzers, because it is capable of providing measurements in all the network subsystems at the same time, using a single analyzer.

Improved Procedure for Earth Fault Loop Impedance Measurement in TN Low-Voltage Network

The difficulties and uncertainties related to earth fault loop impedance measurement are addressed in this paper. Based on the presentation of the measurement procedure implemented in the test equipment (diagrams and measured quantities, respectively, interpretation of results), the shortcomings and errors that accompany it are highlighted. The position in the power system, the influence of power transformers, and the use of effective quantities instead of phasors are important sources of errors, but, as will be seen, the switching of loads at the consumer sides and/or the occurrence of fault regimes during measurements can lead to the most serious impairment of the accuracy in the impedance assessment. The clarification of these aspects is achieved, both starting from the equivalent diagrams of the measurement circuits and the analytical interpretation of the phenomena associated with the measurements, as well as based on the modeling and simulation of TN low-voltage electrical distribution networks, in a specialized program, Eaton xSpider, which allows the complete and complex analysis of a large number of scenarios. Thus, essential conclusions were drawn regarding the level of errors and their causes, obviously, with the research coming with solutions to be implemented at the level of the measurement protocols of the devices used.

Unified Energy Agents for Combined District Heating and Electrical Network Simulation

A sustainable and climate-friendly energy supply needs flexible and efficient distribution systems. Key factors to implement this kind of systems are intelligent coordination (smart grid approaches) and the integration of different energy sectors. This article introduces the unified energy agent as an agent-based approach for a comprehensive modelling and control of energy conversion systems. This approach enables both the simulation and optimization of coupled energy networks, and then in a next step, the development of corresponding smart grid solutions to be applied in the field. Its applicability for the simulation of coupled networks is presented by a real-world use-case of an innovative combined heat and electrical network, which was implemented for the city of Lemgo, Germany. Preliminary results from the project are discussed and an outlook on future work is given.

Modeling of multi-physics transients in PEM fuel cells using equivalent circuits for consistent representation of electric, pneumatic, and thermal quantities

Digital simulators of electric networks have been indispensable tools for engineers and researchers engaged in the analysis and design of electric power and energy systems. With the increasing interest to extend electric energy toward multi-energy systems covering multiple energy carriers, there arises a need to also extend the capabilities of today’s simulators. Such an extension is proposed here in the form of a Proton Exchange Membrane Fuel Cell (PEMFC) model that covers the multi-physics transients involved in the flows of the electric current, hydrogen and other gases, and the enthalpy. The modeling makes use of given analogies to allow for a uniform representation of electric, pneumatic, and thermal transients based on electric circuit equivalents. It is shown how these models representing different transients are coupled as part of a PEM fuel cell system. Validation and application are carried out to verify the value of the modeling. The investigations are performed with an electric network simulator of type EMTP (Electromagnetic Transients Program) and so substantiate the possibility of using the latter for studying multi-energy systems.

Strategies for defect-tolerant microconcentrator photovoltaic modules

One advantage of microconcentrator photovoltaics (μ-CPV) is the range of possible circuit connection arrangements. Large numbers of cells can be connected in combinations of series and parallel strings, which can provide a means to protect the module against performance loss due to cell failure, cell shading, and other variations in cell parameters that may arise during the fabrication and wiring processes. We introduce a model to evaluate the best strategy for optimizing module reliability through circuit layout using a combination of series and parallel connected cell strings. The model uses realistic solar cell device parameters in an electrical network simulation, coupled with a Monte Carlo method to introduce defects into the array with different probabilities. We use the model to optimize the layout of a μ-CPV panel designed to be integrated with the conventional 60-cell crystalline silicon panels for diffuse light capture to produce a hybrid direct/diffuse CPV product.

Simulation of Electrical Grid with Omnet++ Open Source Discrete Event System Simulator

Abstract The simulation of electrical networks is very important before development and servicing of electrical networks and grids can occur. There are software that can simulate the behaviour of electrical grids under different operating conditions, but these simulation environments cannot be used in a single cloud-based project, because they are not GNU-licensed software products. In this paper, an integrated framework was proposed that models and simulates communication networks. The design and operation of the simulation environment are investigated and a model of electrical components is proposed. After simulation, the simulation results were compared to manual computed results.

Robust Estimates for Validation Performance Indexes of Electric Network Models

The validation of an electric traction network simulator is addressed by selecting the testing conditions and considering three performance indexes, which evaluate both simply amplitude and other curve features. A common interpretation scale is proposed to verify the agreement between them. Moreover, since the most complex cannot be fully used without a graphical representation of its output, this is simplified, in order to conclude the validation with an estimate of accuracy that is as close as possible to the classical declaration that accompanies measuring instrument.

Solving hyperbolic heat conduction using electrical simulation

In the present study, the electrical network simulation method is proposed to solve the hyperbolic and parabolic heat conduction problem considering Cattaneo-Vernoute (C.V) constitutive relation. Using this new proposed numerical model and the electrical circuit simulation program HSPICE, transient temperature and heat flux profiles at slab can be obtained easily and quickly. To verify the proposed method, the obtained numerical results for cases of one dimensional two-layer slab under periodic boundary temperature with perfect and imperfect thermal contact are compared with the published results. Comparisons show the proposed technique might be considered as a useful tool in the analysis of parabolic and hyperbolic thermal problems.

Prediction of silicon PV module temperature for hot spots and worst case partial shading situations using spatially resolved lock-in thermography

In this paper we propose a method to predict hot spot temperatures in crystalline silicon photovoltaic modules operating under critical shading conditions prior to module fabrication. We developed a unique tool to evaluate the damage risk potential for an individual solar cell. We show that shading conditions leading to the most critical hot spot temperature do not necessarily coincide with the shading conditions for the maximum total power dissipation in the shaded cell. In fact, for an adequate prediction of temperature fields and the worst case shading scenario, spatially resolved information of the power dissipation on cell level and a thermal simulation of the module system are indispensable. Our approach is divided into three steps, starting with an electric network simulation of cell operating points for different shading scenarios. For these operating points we perform spatially resolved lock-in thermography measurements of the power dissipation on cell level. On that basis we compute three-dimensional temperature fields inside the module with a finite-element analysis for different realistic module operating conditions. The model is validated with experimental data on a module of industrial cells.

Event-Based Modeling of Rapid Single-Flux Quantum Basic Cells With Timing Jitter

The realizable integration level of rapid single-flux quantum (RSFQ) circuits has reached the order of magnitude of 20 000 Josephson junctions, which enables the creation of advanced complex circuits such as microprocessors or digital signal processors. During the design of those complex circuits, behavioral arrangement alone is insufficient; instead, the inclusion of statistical spread is required for timing and parameter verification. The simulation of complex circuits combined with the consideration of timing jitter effects is a very challenging task for both transient simulation on the electrical network level and simulation with hardware description languages. In this paper, a new approach based on discrete-event simulations is presented. By this method, the pulse-driven characteristics of RSFQ circuits can be directly transferred into a model describing the behavior on the transaction level. The realized models of basic RSFQ cells include stochastic timing effects. This approach is demonstrated by modeling a nontrivial cell and compared against the conventional transient simulation concerning the accuracy of the results and the computation time.

Thermal Coupling in AlGaN/GaN Power Transistors

AbstractThermal coupling in AlGaN/GaN transistors is investigated by means of thermal FEM (finite element method) simulation. The results are combined with electrical network simulation using an electro-thermal model. From the FEM analysis the thermal coupling matrix is established, describing the thermal interaction between the different cells of a power transistor. The matrix allows to extract an equivalent circuit for the thermal coupling in a straightforward way. The electrical transistor model is complemented by thermal ports to connect the cells via the thermal coupling network. The electro-thermal model developed yields information on the distribution of temperature and currents within a powerbar and thus is an important tool in transistor design.

2D network simulation and luminescence characterization of Cu(In,Ga)Se2 thin film modules

ABSTRACTCu(In,Ga)Se2 thin film modules have achieved a high degree of maturity. A major challenge for a large volume production is the development of inline characterization tools allowing the detection and interpretation of defects and inhomogeneities. The combination of luminescence characterization (electroluminescence and photoluminescence) and electrical 2D network simulation is proposed to detect shunt defects, defective interconnects, and photocurrent inhomogeneities. Additionally, simulation allows the assessment of the impact of such defects on the module performance. Our approach enables the implementation of an early warning system in a production line, helps to identify the origin of a reduced module performance, and enhances the understanding of defects and inhomogeneities. Copyright © 2012 John Wiley & Sons, Ltd.

Electric circuits modelling the low-frequency impedance of ideal ion-exchange membrane systems

A network model to represent the low-frequency electrochemical impedance of a diffusion boundary layer (DBL) in an ideal ion-exchange membrane system with simultaneous direct electric current has been proposed. This network model with elements distributed in space is obtained using the principles of the network simulation method in a system constituted by a cation-exchange membrane and two boundary layers adjacent to the membrane, from the Nernst–Planck flux equations, the electrical neutrality condition in the DBL and the Donnan equilibrium relations at the membrane|solution interface. The proposed network model is simulated by using the PSpice electrical network simulation program, not only in systems with symmetric 1:1 electrolytes but also in those with asymmetric 2:1 electrolytes. The results of the simulation for the electrochemical impedance are compared with those obtained from a simplified equivalent electric circuit with lumped parameters constituted by the series association of the ohmic resistance of the system and the well-known Warburg-type impedance. It has been found that for the highest values of the direct current, the low-frequency impedance is constituted by a straight line at relatively high frequencies and a semicircle at vanishing frequencies. The slope of the straight line is higher than 45°, the radius of the semicircle is higher than that of the Warburg impedance at low frequencies, but the characteristic frequency of this arc is not a function of the direct current.

Treatment of L-Fuzzy contexts with absent values

This work shows how to extract the missing information from an interval-valued L-Fuzzy context with some unknown values. Absent values are replaced using implications between attributes with high levels of support and confidence. Three kinds of implications are defined and analyzed for this purpose. We apply these results to an electrical network simulation, where the estimated relations between faulty power lines and voltage measurements can be compared with their real values.

Hybrid Simulation of Large Electrical Networks With Assymmetrical Fault Modelling

Owing to the increasing attention placed on dynamic security assessment in the light of recent blackouts, hybrid simulation, involving the interfacing of electromagnetic transients (EMT) simulators and transient stability (TS) simulators for the more accurate representation of very large electric networks, has been attracting considerable attention lately. The goal of hybrid simulation is to represent complex systems, such as FACTS devices and HVDC terminals, in detail, while ensuring an acceptable representation of the complete system such that control systems and switching devices are well represented. There has been significant success in this area. Most approaches, however, concentrate on contingencies that preserve the symmetry of the system. Asymmetrical faults, for example, have not been dealt with in the literature on hybrid simulation. In this paper we deal with how two very different simulators can be coordinated to work together and produce accurate solutions, even with asymmetrical disturbances. Based on the interaction protocol proposed in the paper, case studies were performed on 9-bus systems and 39-bus systems to assess the performance of the integration on both EMT and TS aspects. Very good results were achieved.

An exact piecewise method for fault studies in interconnected networks

Ever-increasing size and complexity of electrical networks call for new computational tools to cope with serious challenges such as information handling and security, massive data processing, real-time analysis and control, etc. In particular, this paper tries to deal with these challenges in the field of fault studies. Actually, a piecewise or diakoptical solution procedure, corresponding to the decentralized nature of electrical networks, has been adopted using large change sensitivity (LCS) concept. It first modifies the prefault voltage profile across utilities and then modifies their nodal Z bus in such a way to reflect the effect of the whole network in local studies performed by individual utilities, i.e. an accurate federative analysis. Mathematical details of the proposed method as well as a numerical example will be presented. Practically, it has been implemented in an existing software package and simulation results for a typical network using this software are available at the end. Generally speaking, it can be used for distributed simulation of large-scale electrical networks across computer networks with the least investment on computational resources.

Microelectromechanical HF resonators fabricated using a novel SOI-based low-temperature process

This paper reports on a novel silicon-on-insulator (SOI) based low-temperature fabrication process to realize microelectromechanical high-frequency resonators. Key features of the devices are single-crystal silicon resonant beams, 400-nm or 600-nm thin transducer gaps, and gold electrodes. The fabrication process combines bulk silicon micromachining applying deep reactive ion etching, low-temperature deposition of a thin sacrificial oxide layer, and electroplating of the lateral electrodes. The resonant behavior of devices with resonance frequencies f/sub res/ between 420 kHz and 4.11 MHz was characterized as a function of the bias voltage V/sub bias/ applied to the beam. Measurements were performed at ambient pressures p between 5/spl times/10/sup -3/ Pa and 0.5 Pa. Q values up to 52000 at f/sub res/=420 kHz and 6000 at f/sub res/=4.11 MHz were obtained. The interaction of resonator and measurement setup were simulated using an electrical network simulation program combined with a finite element analysis using ANSYS.

Decentralized Simulation of Large-Scale Electrical Networks

The paper reports the Global Network Simulation (GNS) project, which is a distributed computing approach for power system analysis. In this project we have provided facilities for distnbuted web-based simulation of large-scale electrical networks in a well established power system simulator package, i.e. PASHA (Power Apparatus & System Homological Analysis). Possibility of autonomous planning and operation of every individual utility of an interconnected network is the ultimate goal of the GNS. Reduction in simulation time, saving in hardware requirements, detailed and secure analysis, are the greatest gains of the GNS. The software has been successfully test on various networks up to 3000 buses.

Dynamic iteration may fail for partitioned network simulation

AbstractIn many technical applications, complex systems are composed of subsystems that are modelled independently using a network approach. This co‐modelling ansatz is completed very naturally by a co‐simulation approach based on dynamic iteration, where the respective DAE submodels are solved iteratively. For partitioned electric network simulation we show that this approach may fail. As alternative we discuss overlapping techniques based on topological network information.

The computation of consistent initial values for nonlinear index-2 differential–algebraic equations

The computation of consistent initial values for differential–algebraic equations (DAEs) is essential for starting a numerical integration. Based on the tractability index concept a method is proposed to filter those equations of a system of index-2 DAEs, whose differentiation leads to an index reduction. The considered equation class covers Hessenberg-systems and the equations arising from the simulation of electrical networks by means of Modified Nodal Analysis (MNA). The index reduction provides a method for the computation of the consistent initial values. The realized algorithm is described and illustrated by examples.