In the upcoming decades, the scale-up of hydrogen production will play a crucial role for the integration of renewable energy into energy system. One scale-up strategy is the numbering-up of standardized electrolysis units in modular plant concepts. The use of modular plants can support the integration of different technologies into heterogeneous electrolyzer plants to leverage technology-specific advantages and counteract disadvantages. This work focuses on the analysis of technical operability of large-scale modular electrolyzer plants in heterogeneous plant layouts using co-simulation. Developed process models of low-temperature electrolysis components are combined in Simulink as shared environment. Strategies to control process parameters, like temperatures, pressures and flowrates in the subsystems and the overall plant, are developed and presented. An operability analysis is carried out to verify the functionality of the presented plant layout and control strategies. The dynamic progression of all parameters is presented for different operative states, like start-up, continuous operation, load change and hot-standby behavior. It is observed that the exemplary plant is operational, as all relevant process parameter can be held within the allowed operating range during all operative states. Some limitations, regarding the possible operating range of individual technologies, are introduced and solution approaches are conceptualized. Additionally, relevant metrics for efficiency, such as the specific energy consumption and flexibility are calculated to prove the feasibility and show the advantages of heterogeneous electrolyzer plant layouts, such as a heightened operational flexibility without mayor reductions in efficiency.