Modeling and validation of stray-field loss inside magnetic and non-magnetic components under harmonics-DC hybrid excitations based on updated TEAM Problem 21

Purpose This paper aims to propose and establish a set of new benchmark models to investigate and confidently validate the modeling and prediction of total stray-field loss inside magnetic and non-magnetic components under harmonics-direct current (HDC) hybrid excitations. As a new member-set (P21e) of the testing electromagnetic analysis methods Problem 21 Family, the focus is on efficient analysis methods and accurate material property modeling under complex excitations. Design/methodology/approach This P21e-based benchmarking covers the design of new benchmark models with magnetic flux compensation, the establishment of a new benchmark measurement system with HDC hybrid excitation, the formulation of the testing program (such as defined Cases I–V) and the measurement and prediction of material properties under HDC hybrid excitations, to test electromagnetic analysis methods and finite element (FE) computation models and investigate the electromagnetic behavior of typical magnetic and electromagnetic shields in electrical equipment. Findings The updated Problem 21 Family (V.2021) can now be used to investigate and validate the total power loss and the different shielding performance of magnetic and electromagnetic shields under various HDC hybrid excitations, including the different spatial distributions of the same excitation parameters. The new member-set (P21e) with magnetic flux compensation can experimentally determine the total power loss inside the load-component, which helps to validate the numerical modeling and simulation with confidence. The additional iron loss inside the laminated sheets caused by the magnetic flux normal to the laminations must be correctly modeled and predicted during the design and analysis. It is also observed that the magnetic properties (B27R090) measured in the rolling and transverse directions with different direct current (DC) biasing magnetic field are quite different from each other. Research limitations/implications The future benchmarking target is to study the effects of stronger HDC hybrid excitations on the internal loss behavior and the microstructure of magnetic load components. Originality/value This paper proposes a new extension of Problem 21 Family (1993–2021) with the upgraded excitation, involving multi-harmonics and DC bias. The alternating current (AC) and DC excitation can be applied at the two sides of the model’s load-component to avoid the adverse impact on the AC and DC power supply and investigate the effect of different AC and DC hybrid patterns on the total loss inside the load-component. The overall effectiveness of numerical modeling and simulation is highlighted and achieved via combining the efficient electromagnetic analysis methods and solvers, the reliable material property modeling and prediction under complex excitations and the precise FE computation model using partition processing. The outcome of this project will be beneficial to large-scale and high-performance numerical modeling.

Investigation of Electrical Parameters of Interleaved Conductors' Packages in High Power Electrotechnological Installations

Electric currents of the order 100 kA flow in secondary current leads of powerful electrotechnological installations. It causes active power losses and electromagnetic field power dissipation. To improve engineering-and-economical performance it is necessary to minimize pure resistance and inductance of current lead and symmetrize the parameters over phases while designing the installation. The paper considers approaches to formulate modern method for calculation pure resistance and inductance of secondary current leads in powerful electrotechnological installations.Interleaved conductors' packages have been examined as the longest partition of secondary current leads in ore-thermal furnace. The examination was carried out with numerical simulation of electromagnetic field of groups of interleaved water-cooled tubular buses (bus-packages) in ANSYS software. Dependencies of bus-packages pure resistance and inductance and their geometric parameters and interleaving ways for magnetic flux compensation have been obtained. Analysis of obtained results allows defining empiric formulae for calculation of electrical parameters of interleaved packages in powerful electrotechnological installations.

Calculation Method of Pure Resistance and Inductance of Ore-Thermal Furnaces Electrode Holder Tubes

While designing an ore-thermal furnace it is necessary to minimize and balance its secondary current contact jaw electrical parameters. The study deals with the method of calculating pure resistance and inductance of ore-thermal furnace electrode holder tubes. It is significant because the tubes have complicated wires configuration and their resistance is noticeable in current contact jaw total impedance because of the same half-phase currents flow in tube bundles and absence of magnetic flux compensation. Real bent wires are suggested to be approximated by broken lines. After that both existing and proposed by the authors formulas can be used for calculating inductance and mutual inductance of two straight-line wires arbitrary placed in space. Current distribution non-uniformity along separate tubes is taken into account in an iterative algorithm. Currents in wires are assumed to be equal at the first iteration. Then they are corrected at following steps of the iteration algorithm with respect to wires resistances calculation results. Skin effect and closure effect between wires segments are taken into account when pure resistance is calculated. The proposed method has been applied in the development of the software for calculating ore-thermal furnace secondary current-contact jaw electrical parameters. The method has been approbated in the design of the 60 MVA ore-thermal furnace made by ZAO “Electroterm”, Novosibirsk, Russia. The results obtained have been tested with numeric 3D models created in ANSYS environment. Inductance calculation error is 10%, pure resistance error is 25%.