| The establishment of an integrated energy network system with multi-energy flow interconnection such as power grid,heat network and gas network,namely the integrated energy system(IES),is conducive to the control of energy flow,the efficient utilization of energy,and the development and use of green energy.There is a close coupling relationship between water,electricity,gas and heat at the spatial and temporal level,and there are good conditions for the construction of IES in oil and gas field sites.Therefore,it is necessary to study the dynamic model of multi-energy system and the coordination control among various systems in order to improve the energy complementarity and mutual aid ability of the oilfield IES and improve the security and reliability of the oilfield integrated energy supply network.Firstly,aiming at the modeling problem of IES non-electric energy system,this thesis established the electric equivalent model of natural gas pipeline,hot water pipeline and steam pipeline by studying the dynamic operation characteristics of natural gas pipeline and thermal pipeline and combining the unified energy path theory.In addition,other necessary equipment in the non-electric energy system were studied,including natural gas compressor,water pump,flow control valve,electric hot water boiler,gas steam boiler.After analyzing the working characteristics of the above equipment,the mathematical model were established,and then the power equivalent model was established.Thus a complete equivalent model of natural gas system,hot water heating system and steam heating system was formed.Secondly,the control models of dynamic components in the power system,thermal system and natural gas system were established according to the power-gas-thermal coupling situation in the field.The photovoltaic characteristics of the actual operation of solar cells were obtained and studied;The voltage and current double closed-loop control model of photovoltaic array inverter was designed to achieve maximum power tracking and output voltage stability control.The V/F controller of AC-DC-AC frequency converter was designed to realize frequency control of natural gas compressor.Based on the power system analysis software,a dynamic model of the integrated IES of oil field,including AC microgrid,natural gas system,hot water heating system and steam heating system,was established and simulated.Finally,the control strategy of IES electricity-gas-heat in oil field was studied.The PWM controller of the electric hot water boiler was designed to make the electric hot water boiler have good adaptability to the fluctuation of frequency and voltage on the side of the grid;The design of constant temperature PI controller for gas steam boiler and the addition of terminal sliding mode control(TSMC)based on extended state observer(ESO)can eliminate temperature errors faster and achieve fast tracking. |
