Mitigating voltage sag by implementing STATCOM on DFIG-based wind farms connected to a power system

摘要

Due to variation of environmental condition, power generated from a renewable source of energy always fluctuates. In the same way, by injection of wind power into the electric grid some power quality may varies because of a wind fluctuating inherent and relatively new types of generators. The measurements and the guidelines indicated in International Electro Technical Commission 61400 Standards the quality of power generated and the performance of wind turbines are derived. As far as the measurements of the generated power quality is concerned while the turbine is connected to an electrical grid there are certain associated powers such as active and reactive powers, flicker, the switching function's electrical behavior, voltage swell, harmonics and voltage sag. Their measurements are done according to national and international guidelines. Nowadays, grid connected doubly fed induction generator becomes an interesting topic for power engineers to focus on. Moreover, voltage stability becomes an important factor to maintain the DFIG-based wind farm functioning during disturbances. This paper studies the static synchronous compensator implementation in order to address the issue of voltage stability in wind farms connected to the distribution network. STATCOM is used as a dynamic reactive power compensator to stable the voltage at the point of common coupling by protecting DFIG-based wind farm interconnected to the distribution system from going offline throughout and after the disturbances. Results obtain shows that, during the voltage sag voltage drops to 0.7pu and after connection of STATCOM voltage will improve to 0.89pu. The developed system is simulated in MATLAB/Simulink and the results show that STATCOM mitigates the effects of transient disturbances such as, voltage sag in the system and hence improves the stability and performance of wind farm.