Abstract:
Large scale integration of wind power is one of the main
challenges in today power systems. Large off -shore wind farms are
usually connected to grids through long transmission lines or
cables. These weak grid conditions have great influence on the
stability of wind power plant’s operation. This paper analyses the
stability issues raised by integrating wind farms into ac network
with very weak conditions .The paper also proposes a gain schedule
based adaptive controller for the grid side converter to enhance the
power system stability at the point of connection. In order to
identify the weakness level of the grid to generate the appropriate
stabilizing control action an online grid impedance estimation
scheme is introduced. The scheme depends on the Extended
Kalman-Filter (EKF) to estimate the equivalent grid impedance
without the need of active disturbance injection. Using the proposed
control scheme the system can operate under very weak grid
conditions with higher wind power penetration levels. Simulations
under low short circuit ratios are conducted to show the enhanced
system stability using the proposed approach.
