Study On Optimal Supplementary Damping Control For Grid Connected Wind-Storage Power Generation System

Wind energy has been paid more and more attention due to its clean and renewable features in recent years. The penetration of wind energy increased constantly with the in-depth study and technical progress of wind power generation. However, large-scale integration of wind power would influence the secure operation and power quality of gird for its intermittent and principle differerce between wind generator and traditional synchronous generator. Low frequency oscillation has an important impact on secure operation of power system, and for regional grid with higher wind power penetration, this problem would become more prominent. This paper give a solution for the small disturbance stability problem of power system due to large-scale wind power integration:(1) The dynamic model of doubly fed wind generator is established, where wind turbine model, doubly fed induction generator model and control system model are inclued. On this basis, small disturbance stability model of DFIG is established, which is used to analyze the effect of the high penetration wind power integration on the the power oscillation damping.(2)Based on small disturbance stability theory of power system, the principles of active power regulation of wind generator on system damping is discussed. Then, a supplementary damping active power control strategy, which adds damping component on input signal of MPPT control of DFIG, is proposed, and genetic algorithm is applied to design the optimal damping controller.(3)The negative effects of randomness and volatility of wind power on DFIG supplementary damping active power control is analyzed. Then, by improving the supplementary damping control strategy proposed above, a new supplementary damping controller which is adaptive to the change of wind speed is designed, achieving the aim that additional active power exported from DFIG supplementary damping control do not change with its operating point.(4) The inapplicability of adaptive supplementary damping controller when wind speed is low or close to the rated speed is analyzed. Then, in order to make wind power-storage system improve system damping in all wind speed, coordinated damping control strategy of DFIG and storage is proposed.