Method for distributing power for LNG (liquefied natural gas)-storage battery hybrid power ship propulsion systems

Abstract

The invention discloses a method for distributing power for LNG (liquefied natural gas)-storage battery hybrid power ship propulsion systems. The method includes manual control modes and automatic control modes. Ship working modes can be freely switched over in the manual control modes by deck officers according to real-time sailing environments. The automatic control modes include steps of 1), acquiring current rotational speeds n of propellers, SOC (state of charge) values of storage batteries and throttle opening alpha of LNG engines and computing required power P<req> of load of the propellers; 2), defining the minimum limit values N<1> and maximum limit values N<2> of rotational speeds of the propellers, defining charge thresholds SOC of the storage batteries as a and defining discharge thresholds SOC of the storage batteries as b; 3), switching over working modes according to logic threshold energy management strategies when ships normally sail in general water areas; 4), designing fuzzy control strategies for working modes D by the aid of the P<req>, the SOC and P<e> so as to assist logic threshold control strategies. The P<req> and the SOC are used as input, and the P<e> isused as output. The method has the advantages that the problem of power loading hysteresis of existing LNG engines can be solved by the aid of the method, the response speeds of the LNG-storage battery hybrid power ship propulsion systems can be increased, and the operability of the LNG-storage battery hybrid power ship propulsion systems can be improved.

Description

technical field [0001] The invention belongs to the field of hybrid power ships, in particular to a power distribution method for an LNG-battery hybrid power ship propulsion system. Background technique [0002] In the search and exploration of new ideas for energy conservation and emission reduction, LNG, as a green energy source, has become the first choice for future marine fuels due to its significant environmental benefits. However, compared with diesel engines, LNG engines have obvious defects in variable load capacity and speed regulation ability, and there is obvious hysteresis in dynamic response characteristics, so the maneuverability of LNG fuel-powered ships will change in some special voyages. And at the same time, due to the special physical and chemical properties of LNG, the safety performance of LNG fuel-powered ships has declined. [0003] The Chinese patent with the application number 201310225560.2 discloses a structure and a hybrid method of a diesel-el...

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Problems solved by technology

[0005] The above systems and methods improve the working efficiency of the hybrid system to a certain extent and reduce exhaust emissions, but cannot solve the problems of poor dynamic performance and insufficient maneuverability due to the power loading hysteresis of the natural gas engine.

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