Guest Editorial Control and Grid Integration of MW-Range Wind and Solar Energy Conversion Systems

The papers in this special section focus on control and power grid integration of MW-range wind and solar energy conversion systems. Globally, the energy provided by intermittent sources has been steadily increasing. For instance, the electrical energy now supplied worldwide by wind turbines has increased by a factor of more than three with respect to the 2008 figure. Solar-based energy generation has increased by more than ten times over the same period. In total, worldwide electrical energy consumption increased by approximately 6340 TWh from 2003 to 2013. Of that increase, about 11% was covered by a combination of wind power (564.8 TWh) and solar power (122.8 TWh). To meet the challenges created by intermittent energy generation sources, grid operators have increasingly demanded more stringent technical requirements for the connection and operation of grid-connected intermittent energy systems, for instance concerning fault ride through capability, voltage and frequency support, inertia emulation, etc. These considerations, combined with an ever-increasing push for lower cost, higher efficiency and higher reliability, are leading to a steady technological evolution in the areas related to intermittent energy conversion systems. Ongoing developments include new or improved high-voltage converters, power converters with higher power density, control systems to provide ride-through capability, implementation of redundancy schemes to provide more reliable generation systems, and the use of high-voltage direct current (HVdc) links for the connection of large off-shore intermittent energy systems. In all of these technological advances, industrial electronics is undeniably a key core contributor.