Short-Term Distortion and Protection Operation in DFIG-Based Wind Parks during Voltage Dips

Due to the increasing penetration of wind power, grid codes require that the wind farms remain connected to the grid during voltage dips. The harmonic distortion might change during the short-term reduction in the voltage magnitude. Although the distortion only occurs during the short period of the voltage dip, high levels of harmonic might cause mal-operation of the protective devices in a wind power plant. The main negative influence that harmonics can have on wind power plant protection is that it can act unnecessarily. This work analysis the changes in the harmonic content in the voltages and currents during dips in a DFIG-based wind power plant. The results showed that the total harmonic distortion for the voltages in the collector system and at the terminals of the wind turbines increases during asymmetrical dips. The currents were affected for both symmetrical and asymmetrical dips. The third and seventh harmonics were the voltage components that most increased. For the currents, the increase was in the third harmonic and interharmonics.