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This letter presents an improved backward/forward sweep algorithm for three-phase load-flow analysis of radial distribution systems. In the backward sweep, Kirchhoff's Current Law and Kirchhoff's Voltage Law are used to calculate the upstream bus voltage of each line or a transformer branch. Then, the linear proportional principle is adopted to find the ratios of the real and imaginary components of the specified voltage to those of the calculated voltage at the substation bus. In the forward sweep, the voltage at each downstream bus is then updated by the real and imaginary components of the calculated bus voltage multiplying with the corresponding ratio. The procedure stops after the mismatch of the calculated and the specified voltages at the substation is less than a convergence tolerance. The proposed algorithm is tested with three IEEE benchmark distribution systems. Results show that the algorithm is accurate and computationally efficient in comparing with two other commonly used methods. [ABSTRACT FROM AUTHOR]

This paper presents an efficient approach for tracking the location of the electric utility shunt capacitor bank that generates switching transients by a limited number of power quality (PQ) meters. The approach is based on measuring the voltage-disturbance energy variations at the meter buses and phase angle changes at the connected branch current due to the reactive power supplied by the switched-on utility capacitor. Both measured energy and phase angle variations are used to identify the location of the switched capacitor through a rule-based tracking algorithm. The proposed method is then tested with the IEEE 30-bus transmission system to show its usefulness. [ABSTRACT FROM AUTHOR]

Cast alloys and melt-spun ribbons with nominal compositions of Sm(CobalFe0.31Zr0.05CU0.04Bx)z (x = 0.02-0.04, z = 7.5-12) have been synthesized and characterized in a temperature range of 10-1273 K and at fields up to 51. The main phase in the as-cast alloys exhibited a Th2 Ni17 type structure, with a strong uniaxial anisotropy. Minor phases with a TbCu7 and/or CaCu5 structure emerged as z (3d/R) decreased. As a result, the anisotropy field (HA) increased from 67 to 120 kOe, while 4πM8 fell from 12.8 to 10.5 kG at 300 K when z was decreased from 12 to 7.5. For melt-spun ribbons, they are nano-structured in nature and magnetically hard, even in the as-spun state. By lowering the value of z(3d/R) and raising the B content, a finer microstructure and a higher Hci were obtained. Hard magnetic properties of Hci = 4.9-12 kOe, 4πM8 = 9.0-12.0 kG at 300 K have been obtained from ribbon samples. Among them, Sm(CobalFe0.31Zr0.05Cu0.04B0.02)10 ribbon showed the highest (BH)max of 10.8 MGOe at 300 K. A Henkel plot analysis suggested the existence of exchange-coupling interaction between the magnetically hard and soft phases in the ribbon materials. [ABSTRACT FROM AUTHOR]

Laminated (Fe0.7 Co0.3)88 Zrγ B4 Cu1 amorphous HITPERM/SiO2 multilayer thin films have been studied by room-temperature (RT) pulsed inductive microwave magnetometry (PIMM) in single, bilayer, and trilayer films. Switching has been measured in a multilayer film with six (50 nm) HITPERM layers, separated by five (2 um) SiO2 layers. Films were investigated by conventional transmission electron microscopy (TEM), high-resolution TEM (HREM), and superconducting quantum hi reference device (SQUID) magnetometry. HREM and TEM show BCC FeCo nanocrystals to nucleate on top of SiO2 layers. Plan view TEM on the top layer reveals FCC nanocrystals that align in chains with spacing of ∼ 50-100 nm. SQUID magnetometry shows reversal to begin by rotation in a single layer for H < 14.4 kA/m (180 Oe) followed by nearly simultaneous reversal of several layers. A final switching event is thermally activated, requiring fields in excess of 8 kA/m (100 Oe) to switch at 2 K, but switching at the same field as other layers for elevated temperatures (RT). [ABSTRACT FROM AUTHOR]

Very high magnetic field annealing is shown to affect the magnetic anisotropy in FeCo-base nanocrystalline soft ferromagnetic alloys. Alloys of composition Fe44.5Co44.5ZrγB4 were prepared by melt spinning into amorphous ribbons, then wound to form toroidal bobbin cores. One set of cores was crystallized in a zero field at 600 °C for 1 h, then, field annealed at 17 tesla (T) at 4800 C for 1 h. Another set was crystallized in a 17-T field at 480 °C for 1 h. Field orientation was transverse to the magnetic path of the toroidal cores. An induced anisotropy is indicated by a sheared hysteresis loop. Sensitive torque magnetometry measurements with a Si cantilever sensor indicated a strong, uniaxial, longitudinal easy axis in the zero-field-crystallized sample. The source is most likely magnetoelastic anisotropy, caused by the residual stress from nanocrystallization and the nonzero magnetostriction coefficient for this material. The magnetostrictive coefficient λs is measured to be 36 ppm by a strain gage technique. Field annealing reduces the magnitude of the induced anisotropy. Core loss measurements were made in the zero-field-crystallized, zero-field-crystallized-than-field-annealed, and field-crystallized states. Core loss is reduced 30%-50% (depending on frequency) by field annealing. X-ray diffraction reveals no evidence of crystalline texture or orientation that would cause the induced anisotropy. Diffusional pair ordering is thought to be the cause of the induced anisotropy However, reannealing the samples in the absence of a magnetic field at 480 °C does not completely remove the induced anisotropy. [ABSTRACT FROM AUTHOR]

Presents a study which described the structural and magnetic phase transitions in nickel-manganese-gallium ferromagnetic shape-memory alloys (FSMA). Properties of FSMA; Experimental procedure; Results and discussion.