Sensorless control of the hybrid double excitation synchronous aerogenerator in case of high wind speed

Abstract

This paper deals with the problem of the constant-power operating envelope at high speed in the wind energy conversion systems. The considered aero-generator involves a hybrid excitation synchronous generator (HESG). To operate at constant-power, it is recommended to use a feedback flux-weakening control, the hybrid excitation circuit is compatible with the extended-speed-range constant-power operation, the flux-weakening and the anti-windup controls that can be achieved simultaneously. In addition to this, an optimization of the electromagnetic torque is provided to improve the HESG efficiency. However, these controls require the measure of wind speed, rotor flux, rotor speed and aerodynamic torque, which are all difficult in practice and not very reliable. This paper presents a design of sensorless flux-weakening power controller. For the achievement of the above energetic goal without resorting to mechanical sensors, a control observation strategy is developed, based on the nonlinear model of the whole controlled system using only electrical variables measurements. The effectiveness of the proposed regulator is analyzed using tools from the Lyapunov stability. These theoretical results are proved by a series of simulations to show the contribution of hybrid excitation at a high wind speed.