A revolution in power transmission and distribution, driven by environmental and economic considerations, is occurring all over the world. This revolution is spearheaded by the development of the smart grid. The smart grid is bringing profound change to both the power systems and many related industries. This paper reviews the development of the smart grid and its correlation with magnetics, including electromagnetic compatibility issue, magnetic-field-based measurement/monitoring, and magnetic energy storage/conversion. The challenge to the field of magnetics and the usage of the cutting edge magnetics technology in the development of the smart grid are discussed. This paper enables researchers in the magnetics community to be acquainted with the progress in the smart grid and inspires innovative applications of state-of-the-art magnetics technologies in the smart grid.

Magnetics in Smart Grid

A fault current limiter (FCL) is a device that is designed to reduce the impact of fault currents on electricity networks and increase the availability of such networks to consumers. One particular FCL technology that is currently attracting worldwide attention, from both researchers and commercial engineering companies, is the saturated core FCL. This device utilizes the change in permeability between the saturated and unsaturated states of a magnetic core to provide both low steady state losses and effective fault current limiting. Typically the core is saturated using an electromagnetic coil, which can be either superconducting or non-superconducting. Although there have been several studies on the electrical characteristics of this device, the transient magnetic behavior has been largely overlooked. In this paper the magnetic flux characteristics of saturated core FCLs are experimentally analyzed. The study includes the magnetic behavior during both the initial biasing of the cores and during transient fault conditions. The influence of FCL topology and alternative low-cost core materials, on the flux characteristics and overall device performance, is also discussed.

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Experimental Analysis of the Magnetic Flux Characteristics of Saturated Core Fault Current Limiters

Superconducting fault current limiters offer superior technical performance in comparison with conventional methods to limit fault currents. Due to prominent advantages and practical demand, the saturated iron-core superconductive fault current limiter (SISFCL) has been applied on transmission lines and distribution system. Considering the actual structure, the sophisticated equivalent magnetic circuit of the SISFCL was proposed first in the paper. Based on those above, the electromagnetic transient simulation model of the SISFCL was built in Matlab/Simulink. To realize accurate electromagnetic transient simulation, Newton iteration method and fundamental magnetic magnetization curve are introduced into the calculation of the current-limiting inductance during simulation. The transient behavior of the SISFCL in simulation tests illustrated that the proposed method is valid and correct.

Electromagnetic Transient Analysis of the Saturated Iron-Core Superconductor Fault Current Limiter

Regarding the line-type permanent-magnet-biased saturation-based fault current limiter (PMFCL), flux leakage effect is introduced in the modelling scheme to justify and ameliorate the theoretical analysis. The research indicates that the current flowing through the external circuit and the flux through the saturated iron-core are two principal variables in combining the external circuit with the magnetic topology of a PMFCL. Equivalent models coupling both the electric and magnetic circuits are established, in which the PMFCL is considered as a controlled voltage source dominated by the flux through the iron-core. A macro-model for simulation is achieved with MATLAB/SIMULINK software and the wrap-to-zero module is presented to substitute the switch in the simulation model. Experiments are further conducted and are thereby compared with the simulation results, which have verified the effectiveness and the accuracy of the proposed modelling methodology.

Modelling methodology and experimental verification of the permanent-magnet-biased saturation-based fault current limiter

To reduce the requirement of dc-coil-generated magnetomotive force, this paper analyzes the method of using permanent magnets (PMs) to saturate the core. In this paper, a novel bridge-type hybrid saturated-core fault current limiter (BHFCL) is proposed to investigate the influence of PM. For the BHFCL, a bridge structure is designed to guarantee the fault clipping performance, with a fault limiting reactor. In addition, the compact structure of magnetic device and the shared coil of alternating current and dc could reduce cost and losses. To compare the influence of PMs on the performance of BHFCL and to validate the effectiveness of the proposed BHFCL, various FEA simulation models in a simple system are carried out by ANSOFT. The simulation results demonstrate that the BHFCL could achieve considerable energy consumption reduction with little effect on the normal condition voltage drop as well as the fault clipping ability. The BHFCL is efficient in fault clipping, and the performance is shown to depend mainly on the value of the reactor included in the bridge.

A Novel Bridge-Type Hybrid Saturated-Core Fault Current Limiter Based on Permanent Magnets

In this paper, the transient performance of a magnetic core fault current limiter (FCL) saturated by high temperature superconducting (HTS) dc bias winding is investigated by using both 3-D field-circuit coupled simulation and magnetic circuit analysis. A high voltage is induced on the dc HTS winding during the fault current state. The induced voltage is computed and a short circuit coil for the reduction of induced voltage is studied. The numerical computations are verified by the experiment results on an FCL prototype

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Cuixia Zhao

Papers

Transient Simulation and Analysis for Saturated Core High Temperature Superconducting Fault Current Limiter

Correction to: "Transient simulation and analysis for saturated core high temperature superconducting fault current limiter"