| The mine local ventilator can blow away the toxic,asphyxiating and explosive gas or dust in the heading face,effectively avoid dangerous accidents such as gas concentration exceeding the limit and gas explosion,and play a very important role in the safe mining of coal.The mine working environment is bad,and the local ventilator adopts the power supply mode of "double power supply,three specialties and two locks",but it still can not ensure its high reliable power supply.In this thesis,an mine emergency power supply and energy storage system is designed,which is used as the third power supply of the local ventilator to further improve the power supply reliability of the local ventilator.In this thesis,based on the analysis of the power supply mode of mine local ventilator,the access mode,working mode and overall structure of energy storage system are determined;according to the relevant regulations of electrical equipment in coal mine,the characteristics of different types of batteries are compared.Lead-acid battery is selected as energy storage element,and the battery actual data combined with software interpolation fitting method is used to determine the optimal configuration of battery capacity under multi-conditions.At the same time,the topology of two-stage power conversion system(Power Conversion System,PCS)is selected and modeled and analyzed.In the emergency power supply mode,the energy storage system provides emergency power to the local ventilator.Based on the actual line conditions of mine distribution network in coal mine,the control strategy of post-stage DC/AC converter is improved in this thesis.In order to solve the influence of large line resistance of mine low-voltage distribution network on inductive sag control,a virtual impedance loop is introduced to increase the inductance of inverter equivalent output impedance and optimize the sag control effect.In addition,the adaptive power compensation control strategy is adopted to restrain the disturbance of the load power fluctuation and the introduction of virtual impedance to the system voltage and frequency.The simulation model is built in Matlab/Simulink,and the simulation results show that the improved control strategy can not only stabilize the voltage and frequency,but also achieve the equal distribution of reactive power when the two energy storage systems work at the same time.In the online operation mode,the power grid charges the energy storage battery pack.The energy storage battery pack adopts a three-stage charging method,and an anti-saturation PI regulator is used in the voltage outer loop of the battery pack to solve the delay problem when switching from constant current charging to constant voltage charging.The simulation results show that the improved control strategy can reduce the time needed for charging mode switching,avoid high charging voltage,and improve charging safety while realizing smooth charging mode switching.When the online operation mode is switched to the emergency power supply mode,the mode switching logic is analyzed,and the current compensation is used to suppress the switching shock;when the emergency power supply mode is switched to the online operation mode,the voltage amplitude and phase pre-synchronization process is designed.The simulation results show that the control strategy adopted in this thesis can realize the smooth transition of each electric quantity on the AC / DC side during the mode switching of the energy storage system.There are 80 pictures,10 tables and 95 references in this thesis. |
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