Design Of Stabilized-voltage Stabilized-frequency For Fishing Boat Shaft Generator Power Grid

In response to the "double carbon" policy,the marine industry is also actively looking for new measures to save energy and reduce emissions.Compared with diesel generators,axle-belt generators have the advantages of energy saving,easy maintenance and small footprint,and are increasingly used on small and medium-sized fishing vessels.However,during the operation of such vessels,the frequency and voltage of the power supply from the axle-belt generators may be unstable due to changes in the speed of the main engine and fluctuations in the load,resulting in the presence of harmonic components in the input voltage and current to the grid,which may cause shocks to the power-using equipment in the grid,resulting in overload or damage to the equipment and seriously affecting the safe navigation of the vessel.In this thesis,two solutions are proposed based on the study of traditional axle-belt generator systems and the prospect of the development of large-capacity energy storage systems for ships:a PWM-controlled axle-belt generator voltage and frequency stabilisation system and a marine UPS(Uninterruptible Power Supply)for axle-belt generator voltage and frequency stabilisation system.From the circuit principle,the principles of the control strategies of the two schemes are analysed and a simulation model is built to demonstrate their feasibility.In the first scenario,the principle and mathematical model of the three-phase uncontrolled rectifier circuit in the system,the parameters were calculated,the Boost(boost)circuit was added to the system in order to solve the voltage dip caused by the wind and waves emitted by the generator,and the principle was introduced,and finally two inverter control techniques were highlighted:sinusoidal pulse width modulation(SPWM)and current hysteresis loop tracking control technique(CHBPWM),while comparing the voltage waveforms and harmonic content of the two control techniques in a simulation platform,it is found that the system output voltage under the current hysteresis tracking control technique has low harmonic distortion and good quality.Secondly,the second option was studied with a focus on the three-phase phase-locked loop principle and the voltage and current double closed loop control principle in the three-phase inverter circuit,while the principle of battery charging and discharging management of the marine UPS system and its control strategy were designed.Finally,from the simulation,the system was able to respond in a shorter time and output a stable three-phase AC waveform.The thesis then goes on to focus on the second option,as the first option can have a low output power in practical applications and cannot meet the needs of marine electrical equipment.The article provides a detailed design of the various components of the marine UPS prototype,including the battery pack structure,the battery equalisation management module,the voltage patrol module,the boost module and so on,and introduces the software design process for each of the marine UPS systems.This demonstrates the feasibility and reasonableness of the design of this paper,and provides a research idea to solve the unstable grid distortion of the shaft belt generator.