风电场交直流并网系统的储能和柔性直流联合调步控制策略

考虑在风电场交直流混合并网系统中风电场的功率差额可以沿交流线路传递给主网,风电场和主网都存在频率稳定问题,提出储能与柔性直流附加控制参与系统频率调节,优化风电场和主网频率特性。在风电场侧柔性直流换流站中加入基于风电场频率变化的柔性直流频率附加控制,以改善风电场频率特性;将储能系统通过换流器并联在风电场和主网间直流线路上,弥补风电场侧直流附加控制对主网的频率恶化作用,并改善主网频率特性;建立了储能与柔性直流附加控制共同作用下的风电场交直流混合并网系统频率模型。算例分析表明,通过储能与柔性直流附加控制的配合,能有效减少风电场功率平衡被破坏时风电场和主网的频率波动幅度。

Energy storage and VSC-HVDC combined frequency regulation control strategy for wind farm AC / DC grid connected system

The power difference of the wind farm in the AC and DC hybrid grid system can be transferred to the main network, the wind farm and the main network have the frequency stability problem, and the energy storage and VSC-HVDC additional control is proposed to adjust the frequency of the power system and optimize the frequency characteristics of the wind farm and the main network system. First, a VSC-HVDC frequency additional control based on the change of wind farm frequency is added to the wind farm side VSC-HVDC converter station to improve the frequency characteristics of the wind farm. Secondly, the energy storage system is connected to the DC line between the wind farm and the main network in parallel through the converter to compensate for the frequency deterioration of the main network caused by the additional DC control on the wind farm side and to improve the frequency characteristics of the main network. Finally, the frequency model of AC/DC hybrid grid connected wind farm system with energy storage and VSC-HVDC additional control is established. The example analysis shows that the frequency fluctuation of wind farm and main network can be effectively reduced by the combination of energy storage and VSC-HVDC additional control when the power balance of the wind farm is destroyed.