Keywords: wind power, wind energy, electric power loop, electricity grids, stability, voltage planification, fossil fuels, France, power electronics, wind turbines
Why the fossil-fuelled reactor fleet in France will not be affected by an evolution of the wind power capacity
Today's power electronics can confer high-performance adjustment capabilities on any technological object, including the frequency-power and voltage tuning of modern, synchronous-type wind turbines. However, this will not enable such devices to steadily produce electric power from an uncontrolled mechanical energy. Thus they cannot be considered independent generation units: the need to supplement them with traditional means is intensified if they feed a so-called separate grid. The German and Danish electric grids, being essentially in that configuration, are strongly dependent on fossil energy. In France, however, the closed national grid presents a large degree of homogeneity. This grid is centrally managed as a single entity, connected to external systems with which energy is exchanged. The reliable and low-cost control of the national generation-demand system always maintains primary, secondary and ternary reserves that are provided by peak and semi-baseload generation units. These reserves must be able to perform when needed, without fail. Essentially random, wind energy cannot collect such reserves on a daily basis. Thus wind turbines have been excluded from the peak and semi-baseload generation units. Similarly to the frequency-power tuning, the voltage adjustment of the traditional production units comprises primary, secondary and ternary levels. The latter two, remote controlled by a central control centre, modify the local voltage-level setting of the primary loop according to grid parameters that are sometimes far removed from the generation unit concerned. This setting is also modified for three other tuning loops. At times, the final tuning operation demanded of a given unit seems to contradict local generation parameters. Wind power's erratic features obviously make it incompatible with the national grid's elaborate voltage control. In short, Reseau de Transport d'Electricite (RTE) and Electricite De France (EDF) are compelled to restrain the contribution of French wind power to baseload generation.