Controle inercial baseado em gerador síncrono virtual aplicado a unidades eólicas operando no ponto de máxima potência

Abstract

The high penetration of wind generation in the power systems results in control and frequency stability issues, being the decrease of the equivalent inertia of the electric power systems one of the main causes of these problems. In this context, this work proposes an operational and control approach to provide emulated inertial response to wind generation units based on fully rated converter operating at the maximum power point. The inertial contribution of the wind generation unit is increased by means of an adaptive MPPT control and an adaptive virtual inertia constant. The adaptive MPPT control strategy mitigates the coupling between the traditional MPPT control loop and virtual synchronous generator during the period in which the wind generation unit contributes with the inertial response. The proposed control reduces the amplitude of the second frequency dip caused by the acceleration of the wind turbine by choosing the operating point to start the speed recovery stage. The proposed approach also reduces the control effort, the transient caused by the MPPT action, and the energy needed to restore the wind turbine speed. An analytical design method for the adaptive virtual inertia constant is also proposed, considering the wind speed, wind turbine speed deviation, and typical system load variations. The virtual inertia constant is designed for different operational scenarios and assigned to the virtual synchronous generator as a function of the measured wind speed and ROCOF. The results show that the proposed strategy is effective in providing a higheramount of active energy during the frequencydip,improvingthe frequency nadir and the ROCOF. The adaptive MPPT control mitigated the antagonistic effect between the MPPT control and virtual synchronous generator, increasing the inertial contribution of the wind generation unit and mitigating the adverse effects of this coupling. The adaptive virtual inertia enables the use of high values of virtual inertia for typical load variations and prevents the loss of stability of the wind turbine in cases of large load variations.