A comparison between PI & SMC used for decoupled control of PMSG in a variable speed wind energy system

Now a days the entire world is considering an escalating demand for electrical energy as a consequence of the hasty population augmentation. The superior penetration of wind energy technology for electrical power production has been growing since past decade due to the unique impressive features of wind technology viz. pollution free, cost effective, low initial cost, less maintenance requirement etc. Variable speed wind power application is used profusely for maximum wind power extraction as compared to the fixed speed method. To harness wind energy PMSG are often chosen for their attractive attributes such as less weight, no external excitation, small in size, gearless drive which are best suited for variable speed wind power application. But it is very difficult to achieve control over it´s power flow due to coupling between generator flux & torque & random nature of the wind power. These challenges lead to the development of a matured modern control approach known as vector control. In this paper the sensor less vector control strategy has been studied for the control of the machine side converter. Both PI controller based vector control & SMC based vector control schemes are considered in this work and a performance based analytical comparison is made between them. A variable speed direct drive PMSG based system is modeled using Matlab/Simulink and the results are compared and discussed.