Research On Improved Ant Colony Algorithm Applied In The Boiler Steam Pressure Control Of Ship

The marine boiler steam pressure control system is the key part of marine steam power unit control system. A system with good performance can keep the boiler steam pressure to the permitted extent, providing sufficient stable power for the ship and save fuel. However, in a marine boiler steam pressure control system, the performance of the traditional PID control entirely depends on the effect of parameter tuning, the method of which is either dependent on the object model or easy to get into local minimum, so there are some application limitations. As an intelligent algorithm, ant colony optimization (ACO)needs no prior knowledge or stringent initial value, and can solve the complex problem well. It has been applied to many practical optimization problems. However, at present, there are still many defects such as stagnation, longing searching and no enough time of the solution space searching of the ant colony optimization algorithm.Aiming at its low evolution speed and prone to stagnation or local optimum, an improved hybrid ACO is proposed, which combines adaptive pheromone evaporation factor, Gaussian variation of decision variables and boundary self-tuning the decision variables together. Appling to function optimization. The simulation results shows that the hybrid improved ACO with respect to basic ACO has higher degree of accuracy, increased optimization speed and higher convergence ratio. Based on above-mentioned hybrid improved ACO, a chaos improved ACO is provided referencing to chaos theory. Applied into function optimization, the simulation results shows that the chaos improved ACO can overcome the disadvantage of lack of traversal and have higher degree of accuracy, higher convergence ratio and increased optimization performance.The marine boiler steam pressure control system is introduced in this paper, based on the task of boiler fuel system, by mechanism modeling, and under the consider of the load, the mathematical model of the marine boiler steam pressure control system is built.And the improved hybrid ACO and the chaos improved ACO mentioned above were applied into the ship's boiler steam pressure control system for optimization of PID control respectively. After simulation and comparison, the results show that the PID control designed based on chaos ant colony optimization algorithm has better dynamic and stationary performance. Theoretic analysis and the simulation proved the chaos improved ACO's validity.