Steam condensers in power plants are crucial for improving the efficiency of the power generation cycle by condensing and recycling steam from the turbine. We used fractional-order proportional-integral-derivative (FOPID) controller to regulate the pressure inside the steam condenser system. We adopted sinh-cosh optimizer (SCHO) to tune this controller. We analyzed the pressure fluctuations and transient responses to verify the system balance between different operational states. Several well-known algorithms, including the gravitational search algorithm, whale optimization algorithm, manta ray foraging optimization and aquila optimizer, are tested against the SCHO. The simulation demonstrates that the SCHO-based method outperforms other approaches in terms of integral of time-weighted absolute error (ITAE), normalized overshoot, and normalized settling time. The SCHO-based FOPID controller attained a minimal error of 14.80 for ITAE, a minimum percentage overshoot of 6.06%, and the shortest settling time of 17.66 s. The stated values confirm that SCHO-based FOPID controller offers superior and more consistent performance for the system under study. Nonlinear analyses further demonstrate the efficacy of the proposed method in terms of circulating water outlet temperature, cooling water flow rate, steam heat and condenser pressure.