Conventional HVDCs that match the hydropower and thermal power bases at the sending end are typically capable of actively adapting to the load characteristics at the receiving end. However, in the case of the receiving grid under the development of large-scale renewable energy bases, it needs to adapt to the fluctuating characteristics of the renewable energy at the sending end through HVDC coupling. According to the "14th Five-Year Plan", the China Southern Area will develop an asynchronous interconnection architecture where Yunnan and Southeast Tibet simultaneously deliver power to the central-eastern receiving-end grid. The frequency stability risks in the receiving-end grid are significantly influenced by the intraday fluctuation characteristics of Southeast Tibet HVDC. On one hand, existing frequency stability engineering verification methods based on seasonal typical scenarios face severe challenges. On the other hand, the dramatic increase in high-penetration hours of non-synchronous sources (e.g., HVDCs and renewable generation) leads to insufficient conventional frequency regulation reserves, exacerbating low frequency risks in the receiving-end grid during large-capacity HVDC blockings. This paper proposes a frequency analysis and control scheme for the receiving end of Southeast Tibet. It involves scenario generation and reduction methods based on time series production simulation and a static risk index. Besides, it also includes a resource reuse-based frequency control system dominated by multi-resource coordination, according to the new resource endowment of the China Southern Area. The rationality and effectiveness of the above scheme are gradually validated based on the 2025 planning data concerning Southeastern Tibet.