Multiple regional power grids in China have introduced Control Performance Standard (CPS) to assess the performance of inter-provincial tie-line operations, which has played a significant role in improving the power deviation of inter-provincial tie lines and the frequency deviation of the power grid. However, in recent years, during peak electricity consumption months, frequency regulation resources of the provinces in recipient regions are often collectively scarce, and inter-provincial electricity spot market prices are high. The CPS assessment mechanism, which calculates CPS penalties based on a lower fixed price, is no longer effective as the safety net in short-term power and frequency balance. Therefore, a master-slave game model between a regional dispatch center and a provincial dispatch center is proposed to determine the CPS assessment price that ensures the provincial center reserves sufficient Automatic Generation Control (AGC) adjustable capacity: the regional dispatch center sets the CPS assessment price, and the provincial dispatch center decides the day-ahead dispatch plan based on this price. The regional dispatch center adjusts the assessment price based on the dispatch optimization results of the provincial center until the adjustable capacity or frequency deviation of the province meets certain requirements. Case study results show that when the assessment price is set at eight times the highest value of various market prices, the assessment mechanism can motivate a provincial dispatch center to purchase inter-provincial spot electricity and demand response quantities when generation capacity is insufficient, meeting the maximum predicted load and potential forecast errors, thereby controlling the frequency deviation of the interconnected power grid within a certain range.