The embedded HVDC system is a form of DC power system that enhances regional power grids. This paper innovatively categorizes the typical application scenarios of embedded HVDC into three types: transmission section reinforcement, new energy delivery, and power supply zone interconnection. It further pioneers an exploration of the planning approach by breaking it down into three key aspects: identifying embedded HVDC construction demands, determining capacity, and selecting embedding points. For each scenario, specific planning steps are proposed to advance the practical application in reginal power grids. Finally, the planning methods are applied and verified through a case study in Jiangsu, China. Viable embedded HVDC schemes are obtained and compared with the AC approaches.