A control system for a vertical axis wind turbine is presented. The electric load is determined solely from the rotational velocity and the characteristics of the turbine, thus measurements of the incoming wind speed are not required. The control system is evaluated with an aerodynamic vortex model coupled with an electrical model. Three different sets of control system parameters are tested, representing different tradeoffs between a high power absorption and achieving a fast control strategy with high stability. The simulations show that the three control strategies provide a similar power absorption as a reference strategy based on known wind speed. For dynamic simulations with fast changes in wind speed, the fast control strategies are beneficial. All control strategies are stable throughout the simulations when proper power absorption characteristics of the turbine are used. It is also shown that if peak power absorption is estimated at a too low tip speed ratio, the control strategies may inadvertently stop the turbine. (C) 2013 Elsevier Ltd. All rights reserved.