Application of phasor measurement units for monitoring power system dynamic performance

This Working Group is a sequel to a previous working group on Wide Area Monitoring and Control for Transmission Capability Enhancement, which published the Technical Brochure 330 in 2007. Since then the synchrophasor technology has advanced rapidly and many utilities around the world have installed hundreds of PMUs in their networks. In this Technical Brochure, we look at the current state of the technology and the extent to which it has been used in the industry. As the technology has matured, it is also important to understand the communication protocols used in synchrophasor networks and their relevant cyber-security issues. These concerns are briefly discussed in the brochure. The applications of Phasor Measurement Units (PMU) measurements reported here are divided into three categories: (a) applications already installed in utility networks, (b) applications that are well-tested, but not yet installed, and (c) applications that are beneficial to the industry, but not fully developed yet. The most common and mature applications are wide area monitoring, state estimation, and model validation. Out of these three applications, wide area monitoring is well established in the industry. The protection and control applications are emerging as evident from the reported examples. The experience of using remote synchrophasor measurements as feedback control signals is not widely reported by the industry. In parallel to this Working Group, Study Committee B5 had a Working Group on “Wide area protection and control technologies.” The Technical Brochure 664 published by this Working Group in September 2016 reviews synchrophasor technology and discusses the industry experience with wide area protection and control. The North American synchrophasor Initiative (NASPI) is another technical group that has gathered and reported a wide range of PMU experiences of industry and researchers. In summary, the field-tested applications presented in this Technical Brochure are a testimony to the confidence of utilities in the synchrophasor technology. The progress in state estimation techniques indicates that synchrophasor measurements will become a standard part of energy management and security assessment systems in the near future

Milk Synthetic Response of the Bovine Mammary Gland to an increase in the Local Concentratioin of Amino Acids and Acetate

Rates of secretion of components into milk are a function of precursor concentrations and parameters that describe expression of the milk synthetic enzymes and their sensitivity to precursor concentrations. To establish the enzymatic sensitivities of milk fat yield and mammary acetate utilization to circulating acetate concentration, lactating cows were infused for 10 h with 0 or 40 g of acetate/h in an external iliac artery supplying one udder half. In addition, to investigate the possibility that energy supply influences the milk protein response to an elevated amino acid (AA) concentration, 2 different AA profiles were infused with and without acetate. Six cows, fed a total mixed ration of 21% crude protein ad libitum, were infused with AA at 0 g/h, 30 g/h in the profile of rumen microbes, or 30 g/h in the profile of milk proteins, in a 3 × 2 factorial arrangement with the 2 acetate treatments of 0 and 40 g/h, all in a 6 × 6 Latin square. Amino acid infusion caused a 60% increase, on average, in plasma concentration of AA entering the infused udder half. From the microbial AA profile, 49% of infused AA were taken up by the udder half, 42% of which occurred during the first pass. From the milk AA profile, 44% of infused AA were taken up by the udder half, 50% of which occurred during the first pass. There was an 8% increase in yield of milk protein with AA infusion, representing 7% capture, but no effect of the infused profile. Acetate infusion caused a decrease in the yields of milk protein and lactose when AA were infused, but not when AA were absent. Milk fat yields were not affected, although acetate concentrations in plasma entering the infused udder half increased by 123% and mammary uptakes increased by 128%. Mammary uptakes of long-chain fatty acids and β-hydroxybutyrate were not affected by acetate infusion, whereas glucose uptakes tended to increase. It was suggested that excess acetate may have been sequestered in adipose tissue in the udder. Yields of both protein and fat in milk showed a low sensitivity to the concentration of their precursors in circulation. It was concluded that the Km in Michaelis-Menten-type equations describing milk synthesis should be assigned a low value, and that the Vmax is regulated to bring about changes in milk yield and composition

Observational Signatures of Particle Acceleration in Supernova Remnants

We evaluate the current status of supernova remnants as the sources of Galactic cosmic rays. We summarize observations of supernova remnants, covering the whole electromagnetic spectrum and describe what these obser- vations tell us about the acceleration processes by high Mach number shock fronts. We discuss the shock modification by cosmic rays, the shape and maximum energy of the cosmic-ray spectrum and the total energy budget of cosmic rays in and surrounding supernova remnants. Additionally, we discuss problems with supernova remnants as main sources of Galactic cosmic rays, as well as alternative sources.Comment: Accepted for publication by Space Science Reviews, 81 page