A substation planning method that accounts for the widespread introduction of distributed generators (DGs) in a low-carbon economy is proposed. With the proliferation of DGs, the capacity that DGs contribute to the distribution network has become increasingly important. The capacity of a DG is expressed as a capacity credit (CC) that can be evaluated according to the principle that the reliability index is unchanged before and after the introduction of the DG. A method that employs a weighted Voronoi diagram is proposed for substation planning considering CC. A low-carbon evaluation objective function is added to the substation planning model to evaluate the contribution of DGs to a low-carbon economy. A case study is analyzed to demonstrate the practicality of the proposed method.