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Electrothermal coordination (ETC) is introduced for cable based transmission grids. ETC is the term covering operation and planning of transmission systems based on temperature, instead of current. ETC consists of one part covering the load conditions of the system and one covering the thermal behavior of the components. The dynamic temperature calculations of power cables are suggested to be based on thermoelectric equivalents (TEEs). It is shown that the thermal behavior can be built into widely used load flow software, creating a strong ETC tool. ETC is, through two case scenarios, proven to be beneficial for both operator and system planner. It is shown how the thermal behavior can be monitored in real-time during normal dynamic load and during emergencies. In that way, ETC enables cables to be loaded above their normal rating, while maintaining high reliability of the system, which potentially can result in large economic benefits. [ABSTRACT FROM PUBLISHER]

This paper presents an algorithm for the estimation of the time-dependent temperature evolution of power cables, when real-time temperature measurements of the cable surface or a point within its vicinity are available. The thermal resistivity and specific heat of the cable surroundings are varied as functions of the moisture content which is known to vary with time. Furthermore, issues related to the cooling effect during rainy weather are considered. The algorithm is based on the lumped parameters model and takes as input distributed temperature sensing measurements as well as the current and ambient temperature. The concept is verified by studying a laboratory setup of a 245 kV cable system. [ABSTRACT FROM PUBLISHER]

This paper presents statistical data about lightning damage on wind turbine blades reported at different wind farms in the U.S. The analysis is based on 304 cases of damage due to direct lightning attachment on the blade surface. This study includes a large variety of blades with different lengths, laminate structure, and lightning protection systems. The statistics consist of the distribution of lightning damage along the blade and classify the damage by severity. In addition, the frequency of lightning damage to more than one blade of a wind turbine after a thunderstorm is assessed. The results of the analysis show that the majority of lightning damage is concentrated at the tip of the blade. Furthermore, all of the blades involved in the study show great similarity in the distribution of damage along the blade and the characteristics of the damages, even concerning the significant differences in the blades' geometry and materials. [ABSTRACT FROM AUTHOR]