Adaptive Control Strategy for Improving the Efficiency and Reliability of Parallel Wind Power Converters by Optimizing Power Allocation

Abstract

Parallel converters are widely applied in high-power wind energy conversion system because of the limited power capacity of a single converter and demands for improved reliability. The handling power of these converters remarkably varies because of the fluctuating wind power. Using conventional power sharing control results in low operation efficiency of parallel converters at low wind speed and when reliability is not considered. Thus, an adaptive control strategy to improve the efficiency and reliability of parallel wind power converters based on optimizing power allocation is proposed. The efficiency-optimized power allocation between parallel converters is calculated by an exhaustive optimization algorithm, according to the efficiency curve of a single converter. The proposed adaptive control is realized by off-line optimization and real-time application, and can rapidly adapt to the fluctuating wind power. The handling power of the parallel converters is redistributed based on the accumulated power factors of these converters to balance total power stresses and increase lifetime. In addition, power hysteresis control is applied to optimize the transient process. An RT-LAB experiment validates the feasibility and effectiveness of proposed adaptive control. The operation efficiencies and failure rates of parallel converters with different control strategies under distinct wind profiles are compared. Comparative results demonstrate that the proposed adaptive control can improve the operation efficiency and reduce failure rate of parallel system under fluctuating wind.