(1. State Grid Ningxia Electric Power Company, Yinchuan 750001, China; 2. NARI Technology Co. Ltd., Nanjing 211106, China)

First, the importance of regional high voltage direct current (HVDC) transmission to the accommodation of new energy in northwest China is introduced, and the disadvantage of the current regional HVDC power transmission to the accommodation of new energy is analyzed. Then, according to the running characteristics of HVDC system and the demand on the regional electricity market, a mixed integer linear constraint model of HVDC plan is proposed to make the HVDC plan participate in the peak load regulation. Furthermore, a new day-ahead generation scheduling method with regional coordination is proposed to optimize the regional HVDC transmission plan and the generation plan of the send grid, which first analyses the upper and lower safe limits to the power of the HVDC transmission of the end grid based on the security constrained economical dispatch (SCED), and then developes an algorithm based on the security constrainted unit commitment (SCUC) model to optimize the HVDC transmission plan, unit commitment and power plan of the send grid by taking energy-saving and the maximization of the generated energy of new energy as the optimization objective with the adjustment constraint of HVDC transmission plan, system balance, unit operation condition, short-term new energy power prediction, and the grid security constraint as the constraints. Finally, an example of day-ahead generation scheduling of a provincial grid with an HVDC sending system has proved the validity of the method. This work is supported by State Grid Corporation of China.