Study on Control Strategy of Hydropower Asynchronous Integration Coupling with DC Emergency Power Support

摘要

The hydropower group is a kind of weak AC system while hydropower asynchronous interconnected with main network through VSC-HVDC(Voltage Source Converter based High Voltage Direct Current).Thus,VSC-HVDC should be taken part into the system voltage and frequency control,which can enhance the transient stability of power grid while reduce the conventional control costs at the same time.The transfer function of turbine governor is introduced to expound the principle of hydraulic turbine unit participating in DC power support.Different kinds of DC power modulation have been compared which show the difference of power angle recovery after fault between VSC-HVDC and LCC-HVDC(Line Commutated Converter based High Voltage Direct Current)power support,thus the modulation priority of different kinds of DC in the emergency control should be taken into consideration.The DC power support quantity calculation method after fault is proposed in this paper.The emergency coordination control strategy can be formulated by considering with both priority and DC power support quantity under different fault.