Research On Multi-time Scale Real-time Coordinated Operation And Control Method Of AC/DC Hybrid Multi-energy Microgrid

The AC/DC hybrid multi-energy microgrid can give full play to the comprehensive advantages of multi-type heterogeneous energy complementation and AC/DC hybrid power supply and use,improve the utilization rate of renewable energy,and meet the needs of users for different grades of energy at the same time.Through energy cascade utilization,effectively improve the comprehensive utilization efficiency of energy.However,the AC/DC hybrid multi-energy microgrid has the characteristics of AC/DC hybrid connection,multiple temporal and spatial scales,multiple uncertainties,deep coupling of multiple types of heterogeneous energy flows,and different needs of various energy users,and the impact of multiple complex factors greatly increase the difficulty of AC/DC hybrid multi-energy microgrid control.In view of this,based on the national "863" project and the National Natural Science Foundation of China,this dissertation carried out in-depth and systematic research on the thesis titled "Research on Multi-time Scale Real-time Coordinated Operation and Control Method of AC/DC Hybrid Multi-energy Microgrid".The research focus and main results are as follows:(1)The mechanism of multi-time scale real-time coordinated regulation of AC/DC hybrid multi-energy microgrid is analyzed,and its real-time coordinated regulation function architecture is constructed.For AC/DC hybrid multi-energy microgrids,multiple types of distributed energy,energy storage,loads and energy conversion equipment are coupled in cooling-heating-electricity-gas energy supply networks,and large differences of the response times between these heterogeneous energy sources,scattered source-load-storage space layouts,and multiple complex factors such as the AC/DC hybrid connections of electrical subsystems make it difficult for these systems to coordinate control.This paper assesses the time scale of real-time control in terms of minutes,seconds and milliseconds.At the minute-level and second-level time scale,a real-time regulation mechanism of a multi-energy microgrid for an AC/DC hybrid connection is analyzed;on this basis,a horizontal cooling-heating-electricity-gas multi-energy network complements the coordinated interaction between the vertical source-grid-load-storage system and the exchange.This multi-energy microgrid,with a multiple time scale real-time coordinated control function architecture for a DC hybrid power supply,provides theoretical program guidance for real-time coordinated system control.(2)At the minute-level time scale,a multi-objective layered real-time collaborative optimization operation method of multi-energy microgrid is proposed.Aiming at the problem that the overall maximizing benefit needs of the multi-energy microgrid and the individual maximizing benefit needs of each energy subsystem are often difficult to unify,based on the master-slave game theory,the horizontal cool-heat-electricity-gas multi-energy complementation and the vertical source-network-load-storage coordination are established.Interactive multi-energy microgrid integration model;according to the inertial characteristics of various energy sources and the response time of various energy conversion equipment,different optimized instruction cycles are used to optimize different energy sources,rather than a unified optimized instruction cycle for all energy sources Carry out optimization to reduce the unbalanced power caused by random fluctuations in source load;on this basis,based on the second law of thermodynamics,comprehensively consider the adjustment cost and exergy efficiency of the system to carry out real-time collaborative optimization of the multi-energy microgrid,in terms of energy utilization It embodies the principle of "equal grade,cascade utilization",and realizes the efficient complementary matching of multiple types of heterogeneous energy.(3)At the second-level time scale,a source-grid-load-storage distributed autonomy'a centralized and coordinated control method in the AC/DC hybrid microgrid,and the economic optimization of parallel converters in the AC/DC power flow section are proposed.An adaptive collaborative control method is proposed to coordinated the control of source-grid-charge-storage;through the distributed autonomy of the internal source-charge-storage of each submicrogrid in the AC/DC hybrid microgrid,the efficient and stable operation of each submicrogrid is realized.and the submicrogrid can be viewed as a whole.Based on the H? performance index.a network-grid centralized coordinated control between submicrogrids in the AC/DC hybrid microgrid is implemented to realize the real-time power balance of the AC/DC hybrid microgrid and meet the high-quality power consumption requirements of the electric load.Inverters operating in parallel in the AC/DC power flow section clarify the economic and optimal distribution plan of the transmission power between the parallel converters,effectively reducing the total transmission power loss of the parallel converters and thereby improving the economy of system operation.On this basis,an adaptive constant voltage coordinated control method for parallel converters considering the converter power margin is further proposed,which achieves the dual goals of optimal steady-state and dynamic performance of the parallel converters in the AC/DC power flow section.(4)At the millisecond-level time scale,a nonlinear optimal control method of an AC/DC hybrid microgrid converter based on differential geometry theory is proposed.Aiming at the strong nonlinearity of the converter mathematical model in the AC/DC hybrid microgrid,the mathematical model of the converter is accurately linearized based on differential geometry theory,and the frequency adjustment mode of the power system is further used for reference.The nonlinear optimal control method of the converter decouples the output of the primary adjustment of the voltage to the interference,and the nonlinear optimal control method of the converter with the best dynamic response performance for the secondary adjustment of the voltage improves the control of the converter performance,thus optimizing the dynamic response performance index during the control process.In a word,this dissertation makes a systematic and in-depth study on the research on multi-time scale real-time coordinated operation and control method of AC/DC hybrid multi-energy microgrid,and the research results are conducive to promoting the construction of a new power system with new energy as the main body in China.