This paper presents a new H-infinity based robust control scheme applied to a permanent magnet synchronous generator (PMSG) based wind energy conversion system (WECS) to regulate the active and reactive power. During the operation, parameters of the PMSG may vary which may lead to variation in the WECS dynamics, thus, the control of active power and reactive power becomes difficult. The proposed robust H-infinity control scheme is designed for a WECS to achieve effective control of active and reactive power flow between WECS and grid. The effectiveness of this controller is verified by simulation and then through experimentation on a PMSG based WECS developed in laboratory. From the obtained simulation and experimental results, it is envisaged that the proposed H-infinity control scheme provides excellent active and reactive power control in face of parametric uncertainties with satisfactory steady state and dynamic performances. The performances of the proposed controller is compared with that of a second order sliding mode controller. It is found that the proposed controller exhibits superior active and reactive power control performance.