High Order Sliding Mode Control for a PMSG Wind Based System with Grid Support Capabilities

FERNANDO VALENCIAGA; DANIEL FERNANDEZ

IET RENEWABLE POWER GENERATION

INST ENGINEERING TECHNOLOGY-IET

Año: 2015 vol. 9 p. 925 - 934

1752-1416

This paper presents a control design for a grid connected wind energy conversion system based on a gearless permanent magnet synchronous generator (PMSG). The generation system structure comprises a three blade turbine, a 2MW multipole PMSG and a full-scale back to back frequency converter linked to the utility grid. The proposed control scheme allows following dynamical specifications taking into account operational requirements and ancillary services imposed by the recent grid connection codes, i.e reactive power regulation and fault ride through capabilities. The control actions to be applied during normal grid operation are designed through second order sliding mode techniques using a two-stage cascade structure. The multi-variable controller designed attains to regulate the active and reactive power delivered to the grid, minimizing the resistive losses into the generator and maintaining important internal variables into the desired range. This controller presents attractive advantages like robustness against unmodeled dynamics and external  perturbations, finite time convergence to the sliding surfaces and chattering mitigation. To endorse the controlled system with fault ride through capabilities a switching control scheme based on voltage grid measurements is also proposed. The performance of the whole control approach is analyzed through representative simulations which include parameter variations, external perturbations and three phase voltage dips.