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.
Planning of secondary distribution circuits through evolutionary algorithms
In this work, the planning of secondary distribution circuits is approached as a mixed integer nonlinear programming problem (MINLP). In order to solve this problem, a dedicated evolutionary algorithm (EA) is proposed. This algorithm uses a codification scheme, genetic operators, and control parameters, projected and managed to consider the specific characteristics of the secondary network planning. The codification scheme maps the possible solutions that satisfy the requirements in order to obtain an effective and low-cost projected system-the conductors' adequate dimensioning, load balancing among phases, and the transformer placed at the center of the secondary system loads. An effective algorithm for three-phase power flow is used as an auxiliary methodology of the EA for the calculation of the fitness function proposed for solutions of each topology. Results for two secondary distribution circuits are presented, whereas one presents radial topology and the other a weakly meshed topology.