Research On Power Network Planning With Distributed Generation Based On Complex Network Theory

At present,the combination of power grid and distributed generation is extensive.The infiltration of large amount of distributed energy makes the optimization planning and operation of power system especially distribution network more complicated.Using the complex network theory to establish the corresponding power network model,and through its related indicators to measure the structural characteristics effect on the performance of the power grid,this idea and method has proved to be effective.Safety is the primary requirement of power system operation.The vulnerability assessment is of great significance to the planning and operation of power system.At the same time,the requirements of invulnerability of grid structure are also increasing with development of distributed generation.In this dissertation,planning of distribution network with distributed generation based on the theory of complex networks is studied.Based on the traditional power grid,aiming at the characteristics of power grid with Distributed Generation(DG)and considering the transmission of power,the index of structural vulnerability assessment and its significance are put forward.This indicator takes into account the capacity of generation and the capacity of load as well as the effect of distributed generation on the load decreases as the distance increases.Comparison with the results of traditional power system analysis shows that the vulnerability index presented in this dissertation can reflect the actual vulnerability of DG grid and lay the foundation for the subsequent vulnerability assessment.Aiming at the problem of safety and reliability of power system,this dissertation chooses three static safety indexes include line overload,overvoltage of bus voltage and reserve capacity,and uses fuzzy analytic hierarchy process(AHP)to form the evaluation index of the influence caused by the fault of fragile line.Combine it with the proposed vulnerability index to form a safety evaluation index for the vulnerability of the grid with distributed generation and make a more comprehensive assessment of the power grid.Using the IEEE standard system for simulation analysis,identify vulnerable links,assess grid vulnerability,to prove the validity of the proposed indicators.The difference of system network performance before and after the addition of distributed generation to the fragile nodes is studied to prove the effect of distributed generation on improving the performance of the power grid and reducing the network vulnerability.The invulnerability is introduced into the planning of distribution network with distributed generation,and the multi-objective programming model is established to satisfy the constraint conditions.At the same time,the sum of the investment and operation cost of lines and distributed generation is the minimum,and the network is most destructive.Quantum Differential Evolution(QDE)algorithm is used to optimize the access capacity of distributed power supply and network structure.Through the actual example simulation analysis,the quantum computing characteristics can get the optimal programming,and the convergence speed is fast.The simulation results show that the network survivability can be improved with less cost increase,which has certain theoretical and practical value to ensure the safe and stable operation of modern power system.