| With a large number of distributed renewable energy and DC loads connected to the distribution network,domestic and foreign scholars have carried out research on the configuration and operation optimization of AC/DC hybrid power supply system with multi-port electronic transformer(PET).This dissertation takes a high proportion of new energy and DC loads,connected to AC/DC hybrid power supply system through multiport PETs as the research object.A general mathematical model of the core device of AC/DC hybrid power supply system with multi-port PETs is established,and the optimal configuration to meet the flexible energy demand of users,the operation optimization method of multi PETs cluster,the reliability evaluation and optimal configuration of AC/DC hybrid system are studied.The main research contents are as follows:(1)A general mathematical model of multi-port PET in AC/DC hybrid power supply system is proposed.Combined with the internal structure of multi-port PET,its working principle is described,and the power constraint conditions of PET ports are established.Based on the characteristics of port loss,the port loss model and power balance constraint equation are constructed,and the structure model of AC/DC hybrid power supply system with multi-port PETs considering port loss is established.The integrated grid structure of AC/DC hybrid power supply system with multiport PETs is designed,and the topology of multi-level directed acyclic graph is established,which lays the theoretical model foundation for the configuration and operation optimization of AC/DC hybrid power supply system with multi-port PETs.(2)A two-stage mixed integer linear programming(MILP)method based on self-defined energy conversion relationship constraints and meeting users’ flexible energy needs is proposed.The equipment type and capacity configuration of AC/DC hybrid power supply system with multiport PET,as well as the topological connection line planning scheme between energy conversion units,are proposed to solve the complementary optimization configuration problem of multi energy system with variable AC/DC hybrid distribution network structure,complex energy conversion relationship and diverse user needs;Using the standardized model of AC/DC hybrid distribution network with directed acyclic graph as topology structure and the multi-level optimal configuration model considering energy conversion relationship,combined with the energy flow relationship matrix in the network,the conversion relationship between electric to heat,hot to cold,electric to cold and other energy sources is quantitatively described;The optimal configuration of AC/DC hybrid power supply system with multi-port PET is solved to verify the effectiveness of the standardized model and two-stage linear programming method.(3)The structure of AC/DC hybrid power supply system with multiport PET cluster is proposed,and the energy efficiency optimization model of M-station and N-port PET cluster system is established.According to the non-linear characteristics of PET port loss,the mathematical model of PET port loss is constructed by data fitting;Aiming at the multi-layer and multi time scale control mode of multi-port PET cluster system,the control strategy of each port of PET in AC/DC hybrid system is proposed,the energy efficiency optimization model of PET cluster control layer is established,and different examples are set to verify the rationality of the operation control mode and system energy efficiency optimization model of PET cluster,The effectiveness of the model in improving the total energy efficiency of PET cluster system is verified.(4)A reliability evaluation method of AC/DC hybrid power supply system with multi-port PET is proposed.According to the basic principle and topological structure of multi-port PET,the reliability calculation method of PET device and the reliability related indexes of key modules are established;Taking a typical data center load AC/DC hybrid power supply system as the research object,the power supply reliability of PET cluster system is analyzed and modeled;Based on sequential Monte Carlo simulation algorithm,the working state of the actual power supply system with pet is simulated;This paper analyzes the influence of multi-port PET parallel cluster mode and port capacity limitation on the reliability of power supply system,and verifies the effectiveness of the model and algorithm.(5)This paper studies the optimal configuration of AC/DC hybrid power supply system with multi-port PET and various distributed new energy sources.A two-layer optimal configuration method for inner layer operation and outer layer configuration is proposed,based on NSGA-II algorithm.By setting 10 k V bus power mutual benefit of cluster system with PET,the PET port capacity configuration under normal operation and N-1 fault is considered,Finally,an example of location optimization of AC/DC hybrid power supply system with multi-port PET integrated into distribution network is given to analyze the impact of multi-port PET on the optimal configuration of AC/DC hybrid power supply system integrated with multiple distributed new energy.Finally,the paper summarizes the whole paper and further explains the future research direction. |
