Research On Operation Control Strategy Of Multi-Energy Complementary Microgrid

With the goal of "carbon peak,carbon neutral",the use of renewable energy has become the key,but due to the large fluctuation of renewable energy output,large-scale integration into the grid will lead to power quality degradation,so the microgrid has become an important way of renewable energy consumption.AC microgrid has become the main form of microgrid at this stage because of its flexible configuration and low construction cost.Therefore,in this paper,the operation control strategy of the microgrid is investigated by taking the scenery-methane storage multi-energy complementary AC microgrid as the research object,and the main work is as follows:Firstly,the overall structure of the multi-energy complementary AC microgrid is analyzed,and the operation mechanism of "self-generation,surplus online,and grid coordination" is established.The structures of photovoltaic power generation system,wind power generation system,biogas power generation system and energy storage system are analyzed,and the corresponding mathematical models are established according to their topologies and operating characteristics,which provide the theoretical basis for the rest of the paper.Secondly,the control strategy of each distributed micro-source system within the scenery-methane storage multi-energy complementary AC micro-grid is studied.The control strategies of photovoltaic power generation system,wind power generation system,biogas power generation system and energy storage system under grid-connected and off-grid conditions are established through analysis,and the Maximum Power Point Tracking(MPPT)problem of photovoltaic power generation system and the point balancing problem of T-type three-level inverter are focused on,respectively,by improving the gray wolf algorithm and The Maximum Power Point Tracking problem and the mid-point balancing problem of T-type three-level inverter are analyzed.Through simulation experiments,the correctness and effectiveness of the adopted control strategy are verified,which establishes the foundation for the later research on the overall control strategy of microgrid.Then,the principles and modeling process of the common control strategies of microsource inverters are analyzed in detail,and the simulation models of multi-energy complementary microgrid based on master-slave control mode and peer-to-peer control mode are established.The effectiveness of the control strategies of master-slave control mode and peer-to-peer control mode is verified through Matlab/Simulink simulation,and the shortcomings of these two control modes are also found.Combining the advantages of master-slave control mode and hierarchical control mode,the overall control strategy of using master-slave control mode when grid-connected and hierarchical control mode when off-grid is established.Finally,the hierarchical control strategy of microgrid in off-grid mode is investigated.In the off-grid mode,the conventional sag control is used as the bottom layer control,and there are problems such as frequency and voltage drift and reactive power cannot be distributed equally.For the voltage and frequency error offset problem,a distributed frequency and voltage secondary control strategy is used,and the consistency algorithm is applied to the secondary control to achieve the recovery of voltage and frequency.For the problem that the reactive power cannot be distributed equally,the reactive power secondary control is introduced,and the proportional balanced distribution of reactive power is realized through the adaptive virtual impedance.Then the correctness of the voltage,frequency and reactive power secondary control is verified by Matlab/Simulink simulation.Finally,a semi-physical simulation experiment is conducted in RTLAB simulation platform to futher verify the correctness and effectiveness of the proposed two-layer control strategy.