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.
Palm oil shell aggregate for lightweight concrete
Publisher Summary Increased agricultural production and the development of agro-based industries in many countries of the world have brought about the production of large quantities of agricultural wastes, most of which are not adequately managed and utilized. Low-cost building materials can be produced using inexpensive indigenous raw materials. Agricultural wastes that are renewable and are found in abundance in many countries present an interesting alternative to the traditional and sometimes imported building materials, particularly for low-cost construction. The use of agricultural wastes as aggregates in lightweight concrete can provides an alternative to conventional methods for the production of lightweight concrete. Lightweight concrete results in a reduction in the overall deadweight of a structure and provides a significant saving in the overall cost of construction. The use of less expensive alternative lightweight aggregates in the production of the concrete can provide further reductions in expense. The material properties and structural performance of lightweight concrete with palm oil shells as aggregates are similar to lightweight concrete produced using the more common lightweight aggregates such as clinker, foamed slag, and expanded clay. The palm oil shells are hard and are received as crushed pieces because of the process used to release the oil. Manual sieving is necessary to remove the large amount of fine particles. The shells are then air-dried before use. Because the palm oil shells are lighter than the cement matrix, the shells tend to segregate in wet concrete mixes. On the other hand, dry mixes using palm oil shells are relatively more difficult to work with when compared to ordinary concrete. Trial mixes are necessary to achieve a good mix design.