Sensorless load monitoring and management in electric power grid through energy harvesting
The article shows a possibility to measure the instant value of the consumed current in electrical devices or in branches of the electric power grid, without specialized sensors. As it is demonstrated, in some types of electrical networks the neutral conductor could be used as a current sensing device and as an energy source. The measuring of the voltage difference between the neutral conductor and the protective conductor can supply convenient information about the load.
Electric Secondary Distribution System Design
As energy prices and the costs of building new generating facilities continue to increase, electric utilities have started looking for ways to reduce system losses. The secondary distribution system is under scrutiny due to the large number of distribution transformers and high secondary load currents. A companion paper (Gibson et al., 2007) presents a new method of secondary distribution system modeling and load characterization. The secondary distribution system is modeled in terms of a few secondary circuit archetypes. The power demand of each load is derived from actual energy consumption. A computer software using Microsoft Excel has been developed to calculate the losses for all transformer secondary circuits in the pilot area, including energy losses in the service drops, secondary lines, and transformers; thus, the circuits with the greatest losses are identified for further study. The applications of the proposed secondary distribution model and load characterization on the economic analysis and design of secondary circuits are also presented.
An expert system for secondary distribution system design
The authors present the development and use of SECOND, a rule-based expert system (ES) for radial, electric power secondary distribution system design accommodating a projected load growth over a specified time horizon. SECOND is implemented in an integrated environment involving Prolog, conventional languages, and a graphic user interface (GUI) toolkit. SECOND makes use of conventional languages (Fortran/C) for algorithm-based numerical calculations, since Prolog is inefficient for this purpose. It also incorporates a window-based user interface (implemented in C) using the GUI toolkit: SunView. The window handling functions are performed by a set of predicates collected into a Prolog library. The data and information on secondary distribution system components are encoded in state frames (SFs), which organize numerical and nonnumerical data into defined slots. This information is then used by the rule-based procedures to arrive at an acceptable design. >