Integration of renewable resources under spanish grid code requirements: Study of real data measurements in PV power plants

The integration of renewable energy resources into power systems have increased considerably along the last decade, mainly encouraged by the development of new technical solutions and policies promoted as a way to reduce the energy dependence from third-countries. For the Spanish case, the remarkable penetration of renewable energy sources has been mainly driven by wind and photovoltaic power plants. As a result of these relevant modifications in the mix of generation, a set of changes in the grid-code requirements have been proposed by most governments and mainly focused on renewable energy resources connected to the grid and submitted to disturbances (voltage dips). Additionally, the last draft issued by the Spanish Transmission Operator System (REE) has provided modifications and new requirements aiming to support even more severe disturbances and voltage dips. Under this scenario, the present paper discusses the evolution of wind farms and PV power plants in the Spanish power system, describing the requirements and electrical behaviors of these sources under disturbances. Both active and reactive power limits have also described in the paper, including disconnection constraints. Real field-test measurements carried out along several years in different Spanish PV power plants provide a realistic comparison between collected data and current grid-code requirements. This study, also included in the paper, offers a preliminary analysis regarding the severity of grid-code requirements in comparison with real disturbances. Moreover, these data give additional information in reference to the inverter performance under the presence of disturbances, and their electrical behavior in current LV PV power plant installations.