基于VSC-HVDC并网风电场的低电压穿越技术研究

VSC-HVDC系统应用于大规模风电集中并网、远距离输送时,要解决电网故障时风电场的低电压穿越(LVRT)问题。为此,提出VSC-HVDC系统与风电场的协调控制策略。低电压穿越期间,通过HVDC两端变流站对电网提供无功支持并采用基于频率控制的快速功率降低算法控制风电场馈入功率,维持直流线路功率平衡。同时,提出风电机组分层控制,使之与HVDC功率控制相协调,保持风电机组的电压稳定。VSC-HVDC系统与风电场间无需通信连接,无需增加设备投资,具有较好的经济性。最后,算例仿真结果验证了该控制策略的快速性和有效性。

Research on the low voltage ride-through technology of integrated wind farms based on VSC- HVDC

When VSC-HVDC system is applied in wind power integration and long-distance transportation, low voltage ride-through (LVRT) in power grid fault is the main technical problem. A LVRT coordinated control strategy is proposed for the VSC-HVDC based wind farms. During LVRT period, the HVDC converters provide reactive current to the grid and control the output power of wind farm through the quick power reduction method which is based on frequency control, to maintain the power balance of DC system. The wind turbine power control is improved and hierarchical control is designed to make it in harmony with the HVDC control and keep the voltage stability of the wind turbines. Coordinated control strategy without communication connection between HVDC system and wind farms, without increasing investment in equipment, has a good economy. Results of case simulation verify the quickness and effectiveness of the proposed method.