MITIGATION OF HARMONICS AND VOLTAGE VARIATION IN GRID CONNECTED WIND POWER SYSTEM USING STATIC SYNCHRONOUS COMPENSATOR

Abstract

Recently the demand for renewable energy in general and that of wind energy specifically are increasing. The challenges to this energy related with power quality issues especially harmonics and voltage variations are increasing during the integration of large-scale wind power. Power electronics device plays major role in harmonic and voltage variation problems when integrating wind energy to the grid. Adama-II wind farm is set up with variable speed wind turbines coupled with doubly fed induction generator (DFIG) type. To solve these problems, Adama-II wind farm has 3rd and 5th harmonic branch of TKMCR static dynamic Var compensation device and magnetically coupled reactor type SVC which act as a harmonic mitigation, reactive power compensator and voltage regulator. However, they have problems like, sudden changes in capacitors, limited life of operation and low response time. Due to advantages of fast response time, better voltage support and reactive power support static synchronous compensator (STATCOM) is used in this thesis. In this regard, 3 MVAr average rated capacity of static synchronous compensator is needed to mitigate the harmonics and voltage variations at point of coupling (PCC). As FFT analysis shows, due to both back-to-back VSC of DFIG and non-linear load that are connected at PCC, total harmonic distortion of current and voltage at Point of common coupling without connection of static synchronous compensator are 30.21 % and 5.18 % respectively. But after the connection of static synchronous compensator, the total harmonic distortion of current and voltage are reduced to the value 3.39 % and 0.25% respectively. When STATCOM is connected at PCC, the voltage is recovered to the value of 1.048 pu from drop of 0.736 pu due to the connection of nonlinear load and to the value 0.9957pu from drop of 0.6885pu due to linear load. Effectiveness of the developed static synchronous compensator scheme relieves the point of common coupling voltage and current from harmonics distortion to comply with 3% and 5% specified by IEEE 519-1992. For validation of the developed system, MATLAB Power software is used for harmonic and voltage dip analysis. The result analysis by using SVC and STATCOM has been carried and STATCOM performed more than SVC in mitigating harmonics and voltage variation of grid connected wind power.