Research On Power Redistribution Control Of PMS In Dynamic Positioning Vessel

With the land resource is getting less and people paying more attention on marineresource, marine technology is developing in a very fast speed. Dynamic positioningtechnology, as an essential part of point operation and tracking navigation, is attracting moreand more scientists to do research in. Ship power station, providing power for dynamicpositioning, is playing an important part. The stability of ship power system will certainlyinfluences the function of dynamic positioning. It needs the ship power station to have powermanagement system (PMS) with a good controller, so that when marines can still have gooddynamic positioning functions facing extreme conditions. PMS can effectively reduce thefluctuations caused by thrusters while having great torque losses. For this situation, we putforward a new control algorithm: power redistribution control (PRC), to obviously reduce thefluctuations of power and frequency.In this paper, we’ll take the ship:"Offshore Oil299" as the target ship, to analysis thePMS on DP ships and proof the effect of PRC with simulation. The main contents of thisthesis are as follows:Firstly, we analysis the electromagnetic and mechanical characteristics in each part of thepower system in DP ships. We analysis and simplify the mathematical model of diesel enginewith speed control system, synchronous generator system and asynchronous motor systemutilizing the characteristics of power system. Then simulate them with MATLAB/SIMULIKsoftware to provide the foundation for the algorithm validation later.Secondly, we design the PMS, using three kinds of load method to estimate the loadcondition of DP ships and limiting the load over the loading capacity. At the same time, wedesign the redundancy, arrangement of the power system, number of generators andappliances to meet the strict demand of DP system.Thirdly, based on the design of PMS for the target ship, we designed the monitoringsystem with QT. This monitoring system can monitor and show the power and the onlinestatus of diesel engines, generators, thrusters and buses by diagrams or dynamic images. Itprovides physical basis for the continuing research on PRC control algorithm.Based on the summarization of general method of PMS control method used in plants, anew control algorithm of power reallocation is proposed to improve the stability of powernetwork. The control method would track real-time dynamic back feed transmitted fromelectric thruster to power system and allocate power of each thruster to the power aroundnominal power according to fluctuation of network frequency, thus decreased fluctuation and improved network stability. According to simulation of power system usingMATLAB/SIMULINK, performance of different control method is compared; outstandingcontribution of PRC algorithm used in PMS stability keeping is summarized.