Modeling And Control Of Mine Main Fan Switchover System

Mine main fan switchover system(MMFSS)can be described as such a process that according to Coal Mine Safety Regulations,the working fan running for a month must be stopped while the standby fan should be started.During the switchover,it is necessary to ensure safe production of mines.Because the switchover directly affects the stability of the underground airflow quantity and the gas concentration,which are related to the mine safe production.Currently,the mines usually employ the sequence control strategy to perform the switchover using a pre-designed switchover process based on the experience of the operator.The realization way often causes a wide range fluctuation of the underground airflow quantity,and even can lead to fan surge.For the high gas mines,this way can result in the overrun of gas concentration,thereby threatening the mine safe production.Hence,to ensure the mine safe production,it is very necessary to ensure the underground airflow quantity remains a reasonable range and the fluctuation is small.This paper studies the modeling and control methods for a kind of typical fan switchover process.MMFSS is a complex system that is comprised of several ventilation facilities.The complexity is exhibited by that 1)multi-variable and strong coupling.MMFSS contains 7 state variables: the underground airflow quantity,2 airflow quantities through main fan and 4 airflow quantities through the air door.Moreover,the airflow quantity through one air duct can affect that through the other air ducts seriously;2)parameter uncertainty.System model parameters(the underground ventilation resistance,4 air door ventilation resistances,2 main fan ventilation resistance and inertia coefficients)have the direct relationship with the air property and the operating conditions.Hence,it is difficult to meaure these parameters accurately in the laboratory and the practical engineering;3)time-varying dynamics under different operating conditions.During the switchover,the variation of the air property can cause the change of model parameters(2 main fan ventilation resistances).Moreover,the change of the underground operating conditions can lead to the variation of the underground ventilation resistance.The changes of these parameters can result in the variation of system dynamics.Due to the above-mentioned complex characterisctis,the conventional control methods can not achieve a satisfied performance.Hence,the optimization operating control of MMFSS urgently needs to be solved in mines.Based on the Key Research and Development Plan Project of Jiangsu Province “Research and development of the key intelligent measurement and control technologies of mine ventilation safety and energy conservation(BE2016046)”,the modeling and optimization operating control of MMFSS is considered in this paper.(1)The dynamic mathematical model of MMFSS is built by using the theory of the flow fluid network.First,the model is built by combining the flow fluid dynamics and the graph theory.Then,the perturbation analysis method is adopted to analyze the parameters of model.The model parameters are divided into two tupes: main parameters and non-main parameters.Next,based on the practical input and output data,the parameter identification method is used to identify the main model parameters.Finally,comparison with the practical MMFSS shows the effectiveness of the built dynamic model.(2)Based on the dynamic model of MMFSS in the previous section,the decentralized controller that considers fully the pressure head regulation of two main fans is developed.The controller can ensure that i)the underground airflow quantity keeps stable;ii)both main fans work in the safe area;iii)the air door meets with the technological requirements.Finally,the distributed semi-physical simulation platform for MMFSS is designed,and the developed controller is conducted on this platform.Simulations show that the controller can achieve good control effect and the closed-loop system is stable.(3)MMFSS has the characteristics with high nonlinearities?strong coupling?parameter uncertainty and time-varying dynamics under different operating conditions.For such a MMFSS,a multivariable nonlinear adaptive decoupling PID control method is developed by combining nonlinear decoupling PID controller and adaptive algorithm.The proposed controller consists of a linear adaptive decoupling PID controller,a nonlinear adaptive decoupling PID controller and a switching mechanism.The linear adaptive decoupling PID controller can ensure the boundedness of input and output signals,and the nonlinear adaptive decoupling PID controller can improve the system performance.The switching mechanism can ensure the closed-loop system stability and simultaneously improve the performance of system.Finally,semi-physical simulation is used to verify the proposed method.(4)Due to the physical constraints of the opening of the air door,the air door is subject to saturation nonlinearity.For the saturation of the air door,a multivariable nonlinear adaptive decoupling PID anti-windup control method is proposed.The proposed controller is comprised of a linear adaptive decoupling PID anti-windup controller,a nonlinear adaptive decoupling PID anti-windup controller and a switching mechanism.The linear adaptive decoupling anti-windup PID controller can ensure the stability of the closed-loop system,and the nonlinear adaptive decoupling PID anti-windup controller can improve the system performance.The switching mechanism not only can ensure the closed-loop system stability,but also can improve the performance of system.Finally,semi-physical simulation is used to illustrate the proposed method.