Optimization approach to power control of grid side converters during voltage sags

Due to constantly increasing share of renewable energy sources in total installed power, transmission system operators must adhere to ever stricter grid codes in order to maintain stable, secure and reliable power system operation. Grid codes in most of the countries with significant share of wind power require from wind power plants to participate in active and reactive power control, to stay connected to the grid during grid faults, as well as to provide voltage support to the grid during voltage sags. In this paper, a grid side converter power control algorithm based on convex optimization is proposed. The proposed algorithm enables the wind power plant to stay connected to the grid even during severe voltage sags. Due to the fact that maximum peak current is limited no overcurrent tripping occurs. Simulations of balanced and unbalanced voltage sag are carried out in order to validate the proposed power control algorithm.