This study presents a new control design approach for the wind farm voltage regulation using static synchronous compensator (STATCOM). A mode decoupling proportional plus integral (PI) controller, in which the control gains are synthesised by eigenstructure assignment (EA), is proposed for the STATCOM. EA is a state-space approach, which is used to improve system damping by eigenvalue assignment and alter system mode shape by eigenvector assignment. To embed the physical PI control loops in the state-space model, an equivalent transformation is proposed to map the feedback gain matrix to the PI controller. Owing to the presence of the physical PI control loops, the control signals would not mire into saturation when appropriate limiter according to the STATCOM capacity is placed in the control variables. To further alleviate the undesired oscillation mode excited by transient disturbance, a lead-lag-based supplementary damping controller (SDC) is adopted. Simulation comparisons are provided to show that the proposed technique can be an effective method for mitigating the voltage fluctuation in the wind farm because of the load changes and the wind gust.

This paper presents the controller design and a simple method to identify the aerodynamic performance for an installed vertical axis wind turbine (VAWT). The hardware realization of the wind energy conversion system consists of a 1.5kW VAWT-driven permanent magnet synchronous generator (PMSG), a PWM rectifier and a grid-tied PWM inverter. The PWM inverter is mandatory to maintain the dc capacitor voltage mainly adapted for operating in parallel with the power grid. The PWM rectifier, serving as a speed governor, is employed to modulate the revolution speed of the VAWT according to the desired power-speed curve so as to extract maximum power from the wind. To guarantee the aerodynamic performance of the VAWT, a simple method, based on the long-term recorded energy efficiency, can determine the optimum power-speed curve for the VAWT. The effectiveness of the proposed strategy is assessed experimentally by examining the closed-loop system response to various wind speeds.