Development and application of distribution network comprehensive analysis system
Through a system study of the fundamental theories of distribution network analysis, operation optimization and network architecture assessment, including static security analysis theory, power flow calculation method, state estimation technique, network optimization method, fault isolation and recovery algorithm, and reactive power optimization algorithm, etc, a graphic distribution network analysis system was developed. Feeder renovation and sectionalization is determined by using the “User Loss Vs Load Loss” charts with both economy and reliability taken into consideration. Interpolation method is used to work out an optimal reactive power compensation capacity, enhancing computational speed. Vector data layering and blocking technique increases the processing speed of the graphic system. The system has been applied in over ten power utilities, and proved effective and helpful.
DEPLOYMENT OF DISCONNECT SWITCHES ON MAIN FEEDER
The deployment of the disconnect switches on the main feeder improves the reliability of a distribution system. However, it adds to the investment cost. There should be a trade-off between reliability requirements and investment cost. In this paper, the consequences of outage to the systems with different deployment schemes of the disconnect switches are analyzed and compared. A theorem is proposed on how to deploy the disconnect switches on the main feeder to achieve the best overall benefit. Our study shows that it should be installed a sectional switch at the beginning of the feeder only when the result of the difference of the system's annual outage cost of the two conditions that there is a sectional switch in a certain section and there are sectional switches in all sections is less than the annual cost of the disconnect switch. An application of this theorem is also given.
Thermal stability of reconstituted collagen fibrils. Shrinkage characteristics upon in vitro maturation
Thermal stability measured as area shrinkage without tension during heating was determined for membranes of collagen fibrils reconstituted from solutions of highly purified rat skin collagens. Shrinkage in per cent of area at 25 degrees C and shrinkage temperature were quantitated in a standardized way and determined as a function of in vitro maturation time for 11 to 104 days after aggregation for the collagen membranes. Similar to reports on intact rat skin, shrinkage temperature remained constant and shrinkage per cent declined with a rate decreasing with time during maturation. Solubility in water at 80 degrees C for 2 hours was 95-96% and remained unchanged for the maturation time (about 2 months) studied. The decreased shrinkage reflecting a lower degree of collapse is ascribed to an increasing thermal stability of the membranes during maturation. Development of heat-stable bonds in the reconstituted collagen fibrils is taken up to be amenable to this increased stability. Similarity in changes of shrinkage characteristics during in vivo and in vitro maturation indicates that maturation changes in reconstituted collagen fibrils reflect those occurring in intact collagen during in vivo aging.