Grid Tied Wind Energy Generating System Incorporating an Observer Based Nonlinear Control Exhibiting Robustness

Abstract

Harnessing effective wind power at its maximum power point (MPP) in a grid tied permanent magnet synchronous generator (PMSG) based wind energy generating system (WEGS), is the core objective of this paper. This very aim is achieved through PMSG speed control using an observer based nonlinear control (ONC) implemented on the wind turbine side converter (WSC), which gets its switching pulses from vector control. The PMSG output power regulation relies on its stator current control, which is attained through PMSG speed tracking. At different wind speed profiles, the PMSG tracks the reference speed decided through MPP tracking algorithm. The design of nonlinear control is based on predicting the response of the system over a horizon of finite time. As the nonlinear control alone is incapable of dealing with the effects of uncertainties, an observer design is included for this very purpose. Hence, the proposed ONC is equipped with the concepts of speed tracking in conjunction with disturbance observation and antiwindup compensation. For control implementation and performance verification, an estimation logic is employed for estimating the PMSG speed, which includes additional benefits like reduced weight, cost and complexity. The test system with the proposed ONC is simulated and results are discussed. A laboratory scale test bed of grid tied WEGS is developed for verifying the performance of proposed control.