One of the biggest problems in Power Quality is the disconnection of electric motors due to the presence of sags. In order to study this phenomenon it became necessary to build a sag generator to, for example, develop immunity curves for induction motors as well as for synchronous motors. In this way it is possible to evaluate the quantitative impact of sags in these machines. This paper also analyzes the effects in current, torque and speed caused by sags, in particular A, B and C types.
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This paper deals with PFC units design related problems in case of installation in harmonics rich environments: in particular the paper contains an overview of sizing approach used in a real case of PFC units design for installation in a steel factory where new PFC units installation has been necessary after a fault with catastrophic consequences for the existing ones. The document contains a report on stresses calculation on PFC units due to harmonic currents generated by non linear loads installed in the above mentioned plant.Read full article
We present the progress of a new project, a field demonstration of a multiple power quality supply system. The project is the first trial to take place in Japan in the area of power quality concepts and solutions. For this project, NTT Facilities developed and installed a multiple power quality supply system that has the capability to feed four classes of alternative current (AC) and one of direct current (DC) power while meeting various customer requirements.Read full article
When a river runs into the ocean and fresh water mixes with saltwater, huge amounts of energy are unleashed. Unlike violent torrents in a waterfall or steaming hot geysers, the energy released cannot easily be seen from the banks of the estuary. Nevertheless, the energy is there, and everyone who has tried to separate salt from seawater knows that large amounts of energy are needed.Read full article
A necessary, but insufficient, condition is that the findings of the researchers can be transferred to common knowledge. One of the main problems in policy design is that the general perception of how markets and economy work is built on simplifications that we all know are wrong, but still prefer to think of as real and true. Some of them are:
That information is perfect for all actors, whereas in reality it is asymmetric. Some know more than others and in some cases we prefer to hide our knowledge or to keep our true valuation of an offer secret in the hope of getting a better deal
Another is that we act as if every problem were new to us, whereas in reality we act with a memory of earlier or similar experiences. We learn and draw conclusions from our learning.
A third is that we are rational and indifferent between options with similar economic outcome. If we earn by hazard 100€ and lose 100€ on the same day, we just shrug it off as if nothing has happened. We are back on zero. Whereas, in reality, we value gains and losses with different scales. Losses give us more grief than the joy we get from our gains.
There are more everyday problems that most economic reasoning and rhetoric tend to forget, but let us stay with these. The Nobel Prize in economics has in the last decade honoured several findings in the areas mentioned, and that may have a great impact on how we handle economics and policy design related to sustainability issues. Read full article