| In response to the needs of offshore oilfield platforms dismantling,multiple units will jointly develop a type domestic semi-submersible lifting dismantling platform.This project is supported by the Ministry of Industry and Information Technology of China high-tech ship project-"Semi-submersible lifting and dismantling platform development"(No.[2017]614)project funding to carry out the modeling and simulation of fast de-ballast system,then conduct research on safe and energy-saving operation.This paper introduces the working principle of the fast de-ballast system,and establishes the mathematical model of the fast de-ballast system,and then simulates the fast de-ballast system,the established fast de-ballast system simulation model in Matlab/Simulink lays a good foundation for verifying different control strategies.At present,the air compressors in the fast de-ballast system use fixed-frequency operation mode with low automation level and high energy consumption,this method will be transformed by variable-frequency operation mode and the variable-frequency control algorithms will be optimized,it is of great significance to improve the safety of platform operations and exploit the energy saving potential of the system.In the fast de-ballast system,the cluster control scheme of the fixed-frequency and variable-frequency air compressors combined is proposed,the common PID control method used by the compressed air station in the factory to adjust the air supply is used to carry out frequency control of the variable-frequency air compressor in the fast de-ballast system,simulation experiments show that this variable-frequency transformation scheme can achieve energy-saving operation of the system,but it takes too long to complete the working conditions.Then conducts in-depth research on the frequency control strategy of the variable-frequency air compressor in the fast de-ballast system,according to the different requirements of different operating conditions of the semi-submersible lifting platform,the corresponding frequency control strategy is proposed.After the variable-frequency transformation of the fast de-ballast system,for the normal working conditions of the semi-submersible lifting platform,on the premise of taking into account safety,with the goal of reducing system energy consumption,combining PSO optimization theory,a fractional order PI~?D~?controller based on PSO is designed to optimize the operating frequency of the variable-frequency air compressor.The simulation experiments show that the fractional-order PI~?D~?controller based on PSO not only inherits the characteristic of the fastness of the fractional-order PI~?D~?controller,but also improves energy-saving performance under the optimization of the particle swarm optimization algorithm,the overall performance is more superior,it is proven to be a suitable variable-frequency control strategy for the normal operating conditions of the semi-submersible platform after the variable-frequency transformation.After the variable-frequency transformation of the fast de-ballast system,for the extreme decoupling condition which the crane suddenly loses its load due to the uncoupling of the cargo in the semi-submersible lifting platform,with the goal of improving the safety of the platform,on the basis of the fractional PI~?D~?control,combined with fuzzy control theory,a fuzzy fractional-order PI~?D~?controller with self-tuning parameters is designed to optimize the power frequency supply of the variable-frequency air compressor.The simulation experiments show that the fuzzy fractional order PI~?D~?controller has the advantage of taking less time than the PID controller and fractional order PI~?D~?controller in the working conditions,the safety of the semi-submersible platform has been improved,and it is supposed to be a suitable variable-frequency control strategy for the extreme decoupling condition of the semi-submersible platform after the variable-frequency transformation. |
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