Modular Multilevel E-STATCOM Using Supercapacitor Based Energy Storage System

The power generated by a wind farm is fluctuating in nature due to the variation of wind speed. This leads to voltage and frequency variation along with some power quality issues which may render to inject large amount of renewable power into the existing AC grid. The stated problem may be addressed by an E-STATCOM which absorbs power fluctuations, such that the grid is seeing the wind farms as a constant power source. The E-STATCOM is formed with supercapacitors where supercapacitors are integrated at the submodules of Modular Multilevel Converter (MMC) through DC-DC converters. The proposed configuration has all features of a STATCOM and is capable to support active power for a definite time span. The integration of supercapacitor into an MMC and associated control are discussed in this paper. The proposed configuration is suitable for high power level due to modular structure and better efficiency. The complete system is simulated in PSCAD/EMTDC to check the performance.