Computation Of Power Losses Research Articles

Power Semiconductor Junction Temperature and Lifetime Estimations: A Review

The lifetime of power electronic systems is the focus of both the academic and industrial worlds. Today, compact systems present high switching frequency and power dissipation density, causing high junction temperatures and strong thermal fluctuations that affect their performance and lifetime. This paper is a review of the existing techniques for the electro-thermal modelling of Mosfet and IGBT devices regarding lifetime estimation. The advantages and disadvantages of the methodologies used to achieve lifetime prediction are discussed, and their benefits are highlighted. All the factors required to predict power electronic device lifetime, including Mosfet and IGBT electrical models, the computation of power losses, thermal models, temperature measurement and management, lifetime models, mission profiles, cycle counting, and damage accumulation, are described and compared.

Asymmetrical multi‐level inverter by using space vector pulse width modulation technique for low and medium power applications

SummaryA DC to AC converter is developed in this paper. This proposes a single‐phase five‐level inverter is developed in such a way that one DC source is used. The structure of the inverter is modular and the capacitor has self‐voltage balancing capability, which eliminates the need for sensors or an additional control loop. This paper presents the schematic diagram of the proposed topology, principle of operation, and the concepts of sinusoidal pulse width modulation (SPWM) for single‐phase and space vector pulse width modulation (SVPWM) for three‐phase. To further prove the advantage, power loss, and parameter computations are calculated mathematically. Low‐voltage stress is achieved in the proposed topology because the blocking voltages of all the switches are constrained to the input voltage. A comparison table is presented between SPWM and SVPWM schemes in three‐phase inverter. The proposed asymmetrical five‐level configuration setup is constructed, and experiments are performed inside the laboratory. The controller of the converter has been implemented in the field‐programmable gate array (FPGA) platform. In order to confirm the viability of the suggested topology, experimental results are provided for single‐phase arrangement. By using the FPGA platform, real‐time implementation is done for a three‐phase inverter topology.

A Single-Stage Closed Loop Control of SC-Based Inverter

This work presents a closed loop five-Level grid-connected inverter. The inverter is based on the switched capacitor approach. The suggested architecture has a lower number of components and is able to maintain a voltage balance across the various capacitors in the system. The construction that has been presented offers a number of benefits, including the capacity to produce five-level voltage output, lower current THD, and enhanced efficiency. Additionally, leakage-current in the circuit is eliminated due to the common grounding configuration. The current injected into the grid is controlled by a PI controller. As a result, a carefully controlled current of the desired quality can be injected into the system using just one renewable energy source. In order to test the suggested topology, the level-shifted sinusoidal pulse width modulation scheme is adopted. The design of switched capacitors as well as the computation of power loss in switches is offered. The performance of this suggested inverter topology is evaluated in comparison to other topologies that are recently presented in the literature. In addition, the power losses and efficiency are calculated using thermal modeling of the topology in PLECS software. MATLAB-2018/Simulink is used to simulate and analyze the PV-connected grid system.

A novel load shedding methodology to mitigate voltage instability in power system

Aim. A novel technique for detecting imminent voltage instability is proposed in this paper, accompanied by a novel load shedding approach to protect the system from voltage instability. Methodology. The proposed methodology utilizes the computation of nodal reactive power loss to voltage sensitivities with load increments in the system. Originality. The nodal reactive power loss to voltage sensitivity is a novel computation and is explored to detect the likelihood of voltage instability in this work. Results. If the system is experiencing an unprecedented load growth and if all the measures reach their limits, then load shedding is the last resort to safeguard the system against instability. The sudden change in nodal reactive power loss to voltage sensitivities is utilized to devise the quantity of load to be cut in the system. Practical value. The time-based simulations performed in New England 39 bus test system (NE-39 bus), the simulated results show that nodal reactive power loss to voltage sensitivities can be used as a trusted indicator for early diagnosing of menacing voltage instability and the timely implementation of load shedding developed from nodal reactive power loss to voltage sensitivities on the system ensures voltage stability.

A comparative analysis of generation and transmission expansion planning models for power loss minimization

In modern power systems, renewable energy resources are becoming more relevant due to their eco-friendly nature and sustainable electrification. Therefore, it is important to consider the effects of the renewable energy resources (RERs) on the generation expansion planning and transmission expansion planning (GTEP) simultaneously. The proper assessment of power losses is essential in order to adequately evaluate the consequence of renewable energy resources in power systems. This paper presents multi-objective optimization problems that are solved using DC, modified DC and AC modelling methods in order to accurately and efficiently compute electrical losses and its impacts on the expansion planning procedure. This paper develops a Mixed Integer Non-linear Programming (MINLP) problem and was solved using CONOPT and CPLEX solvers embedded in Algebraic Modelling Language. The proposed methods are evaluated and validated on three case studies: IEEE Garver’s 6 bus system, IEEE 24 bus test system and a real-world Nigeria Power System. A comparative analysis of the three modelling approaches and a sensitivity analysis of the simulation results indicate that AC solution method provide an accurate computation of power losses and efficient optimal planning strategy as compared to the modified DC method.

A Novel Graph-based Routing Algorithm in Residential Multi-Microgrid Systems

The complementary energy exchange between residential microgrids aims at decreasing the dependence on the main grid, reducing the size and cost of the energy storage units, and increasing energy efficiency. In this regard, the use of a power router interface to connect the microgrids to the power system is necessary for controlling bidirectional power and data flow, which will build the core of the future Energy Internet. In fact, the power router is served as an energy exchange center that enables energy flow between microgrids. One of the most important factors in determining multimicrogrid system performance is the energy routing algorithm strategy. In this article, a new routing algorithm is proposed based on the graph theory. The objective of the proposed algorithm is to minimize the overall power losses with respect to congestion and reliability. Therefore, the best set of loads, optimal sources, and no-congestion minimum loss paths are determined. Various analysis cases have been investigated to confirm the performance and flexibility of the proposed algorithm. A novel case study with multisources and multiloads is addressed, which has not been previously analyzed with the application of power routers. In addition, the developed algorithm is compared with other existing algorithms in terms of power loss minimization, different scenarios, congestion management, computation time, and complexity.

CSI and CSI7 current source inverters for modular transformerless PV inverters

Current source inverter (CSI) is a class of power electronic converters that, thanks to the inherent boost capability and ease of control, is investigated for grid-tied photovoltaic power conversion applications. Traditional CSI and CSI7 topologies are here analyzed and compared with two kind of space vector modulation strategies mainly in terms of ground leakage current both in simulations and experiments. Furthermore, THD of the injected grid current and the computation of conduction and switching semiconductor power losses are also carried out in numerical simulations. The topology comparison is carried out with the use of a different number of PV modules, to analyze the robustness of the topologies to different size of the PV strings. Simulation and experimental results show that the CSI7 topology, with respect to conventional CSI, allows to strongly reduce ground leakage current, phase current THD and semicondutor power losses, at the price of an additional power device.

An energy-efficient torque-vectoring algorithm for electric vehicles with multiple motors

In electric vehicles with multiple motors, the individual wheel torque control, i.e., the so-called torque-vectoring, significantly enhances the cornering response and active safety. Torque-vectoring can also increase energy efficiency, through the appropriate design of the reference understeer characteristic and the calculation of the wheel torque distribution providing the desired total wheel torque and direct yaw moment. To meet the industrial requirements for real vehicle implementation, the energy-efficiency benefits of torque-vectoring should be achieved via controllers characterised by predictable behaviour, ease of tuning and low computational requirements. This paper discusses a novel energy-efficient torque-vectoring algorithm for an electric vehicle with in-wheel motors, which is based on a set of rules deriving from the combined consideration of: i) the experimentally measured electric powertrain efficiency maps; ii) a set of optimisation results from a non-linear quasi-static vehicle model, including the computation of tyre slip power losses; and iii) drivability requirements for comfortable and safe cornering response. With respect to the same electric vehicle with even wheel torque distribution, the simulation results, based on an experimentally validated vehicle dynamics simulation model, show: a) up to 4% power consumption reduction during straight line operation at constant speed; b) >5% average input power saving in steady-state cornering at lateral accelerations >3.5 m/s2; and c) effective compensation of the yaw rate and sideslip angle oscillations during extreme transient tests.

Computing Active Power Losses Using a Mathematical Model of a Regulated Street Luminaire

Before the use of regulated street luminaires with variable power and luminous flux, computations were performed using constant values for their electrical and photometric parameters. At present, where such lighting is in use, it is no longer possible to base calculations on such assumptions. Computations of energy and power losses, for example, need to be performed for all dimming levels and based on the applied regulation algorithm. Based on measurements carried out on regulated luminaires, it was found that certain electrical parameters have a nonlinear dependence on the dimming level. Electrical parameters were also observed to depend on the value of the supply voltage. The results of the measurements are presented in this article. Failure to take account of power losses in computations of the energy efficiency of street lighting in accordance with the applicable EN 13201 standard causes values of energy efficiency indicators to be overstated. Power loss computations are presented in this article for a sample street lighting system with regulated luminaires, for the whole range of dimming levels and additionally for fluctuations of ±10% in the supply voltage. In addition, a mathematical model of a regulated luminaire is constructed with the use of regression methods, and a practical application of that model is described.

Design of a brushless DC permanent-magnet generator for use in micro-wind turbine applications

This paper deals with the optimal design of a direct-driven brushless DC permanent-magnet (BLDCPM) generator over a long-term wind speed cycle operation. Such a large wind speed profile causes long processing time in the search of the optimal solution, therefore a simplification method of the profile based on an original barycenter method is proposed and applied to the power losses computation of the wind energy system. As a result, the optimization methodology relies on two modeling levels different in simulation time and approach and is based on a constrained mono-objective problem with adequate optimization strategy and algorithm that aims at reducing the global system power losses for the given wind speed profile while finding the optimal geometrical and electrical features of the BLDCPM wind generator.

Optimizing wind farm cable routing considering power losses

Wind energy is the fastest growing source of renewable energy, but as wind farms are getting larger and more remotely located, installation and infrastructure costs are rising. It is estimated that the expenses for electrical infrastructures account for 15–30% of the overall initial costs, hence it is important to optimize their design. This paper focuses on offshore inter-array cable routing optimization. The routing should connect all turbines to one (or more) offshore substation(s) while respecting cable capacities, no-cross restrictions, connection-limits at the substation, and obstacles at the site. The objective is to minimize both the capital that must be spent immediately in cable and installation costs, and the future reduced revenues due to power losses. We present a Mixed-Integer Linear Programming approach to optimize the routing using both exact and math-heuristic methods. In the power losses computation, wind scenarios are handled efficiently as part of the preprocessing, resulting in a model of only slightly larger size. A library of real-life instances is introduced and made publicly available for benchmarking. Computational results on this testbed show the viability of our methods, proving that savings in the order of millions of Euro can be achieved.

Outstanding Outcomes from a Recent Theory of Gravity

This article intends to fathom a development by M. Tailherer which introduces a second gravitational equation devised to complete General Relativity (TGR), based on the ansatz of equating the curvature tensor opportunely contracted to the 4-vorticity by a new constant S as measure of the intrinsic inertia of the curved Space-Time. After justifying the need to deal with the 2nd fundamental tensor in Relativity in discussing the dynamics of Space-Time structure, it has been shown how the model exhibits unforeseen analogies with the electromagnetic theory. As direct continuation of the analysis of the gravitational wave propagation in free space, it has been seen that on asymptotic conditions the polarization state can be retrieved as mixture of two independent modes likewise TGR as from harmonic constraints on the homogeneous solution of wave equation. Actually, in this gravitational framework, at least for one polarization state, transverse waves propagate causing equal in-phase deformation displacement, not counter-phase as expected in gravitational interferometry experiments at present status. Computation of gravitational power losses for the keplerian system B 1913+16 in the solution by approximations of the inhomogeneous problem has been carried out to the 1st order, which has allowed the assessment of a new universal gravitational constant for the first time ever.

State Space Averaged Modeling and Power Loss Computations for Fuel Cell Powered Four-Phase Interleaved Boost Converter

This paper investigates the state space averaging of a four-phase Interleaved Boost Converter (IBC) powered by fuel cells. The state space averaging technique is a method to model the converter as time independent which is defined by a set of differential equations which will be useful for designing the controllers [18]. In this paper, mathematical models developed using state space averaging technique are presented for the proposed IBC. The power loss calculations are also computed. Simulation of IBC with fuel cell as the source is carried out in MATLAB and the results are presented and discussed.

Diagonal Mesh Equivalent (DME) for the calculation of the hysteresis losses in electrical machines

The Magnetic Equivalent Circuits (MECs) technique is a powerful tool for machine analysis and power losses computation. Here, use is made of the Diagonal Mesh Equivalent (DME) to solve the equivalent electrical circuit for the branch fluxes to be easily computed and related to the machine compartments of technical interest. These are represented by the air gap, stator and rotor to name a few. Hysteresis loops have been computed, along with the static power losses, for assigned stator thicknesses and compared to ones alternatively obtained by the Modified Scalar Preisach Model. This study is especially aimed at giving improved issues to those who are engaged in the design of magnetic components for electrical machines.

Coupled Electromagnetic and Thermal Analysis of Single-Phase Insulated High-Current Busducts and GIL Systems

This paper presents a mathematical model for the coupled electromagnetic and thermal analysis of the single-phase insulated high-current busducts of circular cross-section geometry and of gas-insulated transmission lines (GIL). The mathematical model, accompanied by a numerical solution procedure, features an exact current distribution in phase conductors and shields of the busduct or GIL system, accounting for the skin and proximity effects, and including the complete electromagnetic coupling between phase conductors and shields. The current distribution is based on the conductor filament method in combination with the mesh-current method. The mathematical model further couples the analysis of current distribution with the computation of (Joule) power losses and subsequent temperature increase in the high-current busducts or GIL systems, accounting for the material properties (electrical conductivity, thermal emission and convection coefficients) as well as for the surrounding ambient properties (ambient temperature, wind and solar radiation influences).

A Computational Algorithm for Corona Power Loss in Grid

In this paper a new efficient algorithm for computation of corona power loss in grid is described. The algorithm is based on a new finite element method (FEM) which allows computing corona power loss in high-voltage lines transmission. The new algorithm method is intended for considering the effects of various parameters on corona current such as: the height of conductor, the radius of conductor, the surface factor, distribution of electric potentials in space of between conductor and ground plane with applying space charges, and ambient temperature. The algorithm results were compared with the existing methods and the result accuracy was confirmed. Also, the results show that the new algorithm has positional to reduce the number of iteration for calculation of the corona current. The knowledge of the corona phenomena discharge will assist in monitoring and controlling the reliability of high voltage systems. This information can be monitored for measuring, detecting and taking appropriate control actions.

The Complete Surface-Current Distribution in a Normal-Mode Helical Antenna

An investigation of the surface-current distribution in a normal-mode helical antenna (NMHA) is reported. This enables precise prediction of the performance of normal-mode helical antennas, since traditional wire-antenna simulations ignore important details. A Moment-Method formulation was developed, using two geometrically orthogonal basis functions to represent the total nonuniform surface-current distribution over the wire of the helix. Extended basis functions were used to reliably treat the discontinuity of the current at the free ends. A surface kernel was used all over the antenna's structure. The surface-current distribution was computed for different antenna geometries, such as dipoles, loops, and helices. For helices, the currents were investigated for different pitch distances and numbers of turns. It was found that the axially-directed component of the current distribution around the surface of the wire was highly nonuniform, and that there was also a significant circumferential current flow due to inter-turn capacitance, both effects that are overlooked by standard filamentary current representations using an extended kernel. The impedance characteristic showed good agreement with the predictions of a standard filamentary-current code, in the case of applied uniform excitation along the local axis of the wire. However, the power-loss computations of the present technique produce significantly different results compared to those well-established methods when the wires are closely spaced.

Power Loss Computation in High-current Generator Bus Ducts of Rectangular Cross-section

Due to the medium voltage level of generator terminals and very high-current output, generator connection to the step-up transformer is often carried out with a so-called high-current air-insulated bus duct system. Due to these high currents, during normal generator operation, accompanying Joule power losses are often very high, which in turn, results in excessive (and even non-permissive) heating of the bus duct system. The solution to the mentioned power loss problem involves a determination of currents in phase conductors and in the shield of the metal-enclosed bus duct system. A bus duct transmission line consists of either a segregated or a non-segregated air-insulated three-phase system. Phase conductors and metal enclosures are both rectangular in cross-section. Here, the developed computation model is based on the conductor filament method with application of the geometric mean distance method. It takes into account both skin effect and proximity effects, as well as complete electromagnetic coupling between phase conductors and metal enclosure.

The effect of finite-difference time-domain resolution and power-loss computation method on SAR values in plane-wave exposure of Zubal phantom

In this paper, the anatomically realistic body model Zubal is exposed to a plane wave. A finite-difference time-domain (FDTD) method is used to obtain field data for specific-absorption-rate (SAR) computation. It is investigated how the FDTD resolution, power-loss computation method and positioning of the material voxels in the FDTD grid affect the SAR results. The results enable one to estimate the effects due to certain fundamental choices made in the SAR simulation.

Simple Frequency Domain Model for Hysteresis and Eddy Currents in Cylindrical and Parallelepipedal Cores

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We develop a simple and approximate model for hysteresis and eddy currents in cylindrical magnetic cores. The model characterizes the core by the magnetic properties of its material (<formula formulatype="inline"><tex>$\mu, \psi_0,$</tex> </formula> and <formula formulatype="inline"><tex>$\sigma$</tex></formula>) and its geometry (perimeter and area of cross section and core length). The model is compatible with common electrical simulators, such as <emphasis emphasistype="smcaps">spice</emphasis>, and allows a fast and approximate computation of both hysteresis and eddy-current power losses, impedance, flux, and field. We extended the model to parallelepipedal geometries, and we checked it by comparison to previous models and by experimentation. </para>