[Objective] Challenges such as adapting to renewable energy power fluctuations and coping with startstop mechanisms exist during the operation of electrolyzers. Capacity configuration models based on long time scales struggle to accurately capture these dynamic characteristics

which reduces the accuracy of capacity planning for hydrogen production systems. [Methods] Taking a hybrid hydrogen production system composed of alkaline(ALK) electrolyzers and proton exchange membrane(PEM) electrolyzers as the research object

this paper proposes a minute-level time-scale capacity planning method for hybrid hydrogen production. First

a minute-level electrolyzer start-stop control model is designed to accurately describe the operating states of the two types of electrolyzers. Second

considering ALK electrolyzers' poor adaptability to power fluctuations and long start-stop time

we develop a power allocation strategy that prioritizes the stable operation of ALK electrolyzers. Finally

we conduct multi-objective optimization for the capacity planning problem of the hybrid hydrogen production system

and the Pareto solution set of the model is obtained via the augmented ε-constraint method. [Results] Simulation results show that under the condition of 20 MW installed wind power capacity and 20 MW installed photovoltaic capacity

with a total system investment cost of 25 million yuan

the proposed 1-minute time-scale model increases the average daily hydrogen production by 14.7%

reduces the unit hydrogen production cost by 7.5%

and decreases the renewable energy curtailment rate by 63.6% compared with the traditional 15-minute time-scale model. In addition

with 1-minute scheduling accuracy

the ALK/PEM electrolyzer capacity ratio is gradually optimized as investment increases: when the total investment is below 25 million yuan

the proportion of ALK electrolyzers exceeds 90%; when the total investment exceeds 30 million yuan

the investment proportion of PEM electrolyzers rises to 19.4%. In contrast

for the 15-minute time-scale model

the ALK/PEM capacity ratio reaches 4:1 even when the investment is only 20 million yuan. This prematurely increased proportion of PEM electrolyzers not only deviates from practical engineering conditions but also degrades overall system performance

indicating that coarse time-scale scheduling may lead to capacity mismatch.