Connection Mode Selection of Near-end Local Power Grid and HVDC Transmission System Considering DC Additional Control Capability

To meeting the grid-connecting demand of the local power grid with small scale and weak grid structure,a connection mode selection method of near-end local power grid and HVDC transmission system is proposed considering DC additional control capability. First of all, on the basis of summarizing the problems of gird-connected and isolated-connected modes, the influence of DC emergency power control and DC additional frequency control on the stability of the sending system is analyzed, and the DC additional control capability has a great effect on selecting the connection mode of small-capacity local power grid. Furthermore, the principle of mode selection is given, and the relevant rules of safety and stability of power system are given. Taking into account the requirements of power flow and short circuit current, the first and the second level of transient safety and stability check sequence and standard are proposed by comprehensively considering the failure probability and its influence on the stability of power system. In addition, according to the characteristic quantity of AC and DC systems that reflect the degree of sensitivity to stability, the transient stability criterion is given. In the end, a practical HVDC project is taken as an example to verify the validity and adaptability of the mode selection method.