A Joint Planning Method for Wind-Solar-Storage Capacity Allocation in New Energy Transmission Bases

China needs to build a massive new energy transmission infrastructure if it hopes to meet its carbon peaking and carbon neutrality targets as well as promote coordinated development in both its eastern and western regions. Ensuring the transmission base operates economically and reliably requires the efficient allocation of diverse new energy sources and energy storage capacity. This paper proposes a capacity allocation method for new energy transmission based on the confidence probability of wind and solar resources. First, an improved K-means clustering method is introduced to optimize the transmission power of the DC channel, taking into account the load curve at the receiving end. Next, a transmission confidence probability index is suggested, which evaluates whether the transmission base's output power can satisfy the DC channel's transmission requirements. The ideal model for the distribution of wind energy and energy storage capacities is constructed with this confidence probability index as a constraint, and it is solved using a stochastic planning technique. In order to verify the efficacy of the suggested allocation model, we lastly examine a case study involving a resource supplier in western China and a recipient region in eastern China.