Modeling and simulation of substation fault diagnosis based on Petri nets
In order to improve the efficiency of the substation fault diagnosis with multiple protections, the proposed method describes protection grades by varied weight of the transition vector in the Petri net models. According to relays and circuit breakers, special markings are produced in the diagnosis results that enhance the identifying capability of error information. The process of fault diagnosis is accomplished by algebra matrix calculation. A simulation on actual substation fault diagnosis process indicates that the improved method has fast calculation speed and high veracity
Extended Petri net models for fault diagnosis for substation automation
In previous work Petri net models were developed by the authors (1977) for detecting fault locations in general. In the current paper, the models have been modified to include backup protection as well as primary protection. The modification overcomes many limitations of the original models. Hence, the advanced models are more capable of analysing fault in a highly meshed network or network with more than one layer of protective devices, such as those in substations. The developed methodology is tested using an actual substation network. Fast and accurate results are obtained, and the proposed method has great potential for on-line applications.
Deliberative Democracy and the Resource Curse: A Nationwide Experiment in Tanzania
Oil and gas discoveries in developing countries are often associated with short-sighted economic policies and, in response, calls to insulate resource management from populist impulses. We report on a randomized experiment testing methods to overcome this apparent tension between sound resource governance and democratic politics. Soon after Tanzania’s discovery of major natural gas reserves, we invited a nationally representative sample of voters to an intensive public deliberation of policy options featuring nationally recognized experts and small-group discussions. Democratic deliberation reinforced the public’s strong preference for rapid spending of gas revenues, but also increased support for various prudential and economically orthodox measures, including independent oversight of gas revenues, limits on government borrowing, and selling gas abroad rather than subsidizing fuel at home. These effects were driven by deliberation per se, rather than a pure information treatment, and show no evidence of contamination by facilitatoror peer-effects in group deliberations. www.cgdev.org Justin Sandefur, Nancy Birdsall, James Fishkin, and Mujobu Moyo