Abstract: Objectives Aiming at the speed control problem of the power generation steam turbine in the marine medium-voltage direct current (MVDC) power system under the condition of sudden load power changes, this study verifies the superiority of Linear Active Disturbance Rejection Control (LADRC) in the marine islanded network environment, and investigates the impact of the Hybrid Energy Storage System (HESS) on the speed control performance of the power generation steam turbine. Methods Based on the MATLAB/SIMULINK platform, a comprehensive simulation model was established, which consists of a marine power generation steam turbine, a marine MVDC power system, and a HESS composed of lithium-ion batteries and supercapacitors. The parameter tuning of the LADRC suitable for marine power generation steam turbines was completed. Simulation comparison and analysis were conducted between the LADRC and PID controllers under typical operating conditions, including 30% and 50% sudden load power increase/decrease, propulsion motor start-stop, and sudden complex load changes. Finally, the impact of the HESS on the speed control of the power generation steam turbine was verified by comparing the scenarios with and without HESS access. Results The simulation results show that: Under the 30% and 50% step disturbances of sudden load power, the speed overshoot of the LADRC is 60% of that of the PID controller; Under the condition of sudden increase/decrease of DC load power (accounting for 30% of the total ship power) in the marine islanded network, the speed overshoot of the LADRC is 59.4% of that of the PID controller; During the start-stop of the propulsion motor (accounting for 50% of the total ship power) in the marine islanded network, the speed overshoot of the LADRC is 51.8% of that of the PID controller; For the power generation steam turbine with HESS access, its speed overshoot during propulsion motor start-stop is 70% of that without HESS access. Under the condition of sudden complex load changes, the average speed overshoot of the LADRC is 50.8% of that of PID Controller (1), and the speed overshoot of the LADRC with HESS access is 76.6% of that of the LADRC without HESS access. Conclusions The LADRC achieves better speed control effect in the marine islanded network environment; The HESS improves the stability and power quality of the marine power system through power compensation, and effectively suppresses the impact of load disturbances on the speed of the power generation steam turbine.