Power Flow Calculation And Optimal Operation Of AC/DC Distribution Network

With the rapid development of economy,the traditional AC distribution networks are facing significant challenges.The continuous increase of DC power supply brings the line loss increases and the voltage fluctuations.With the increasing proportion of DC loads,a large number of power electronic converters are connected to the distribution networks,which leads to the reduction of the operation efficiency of the distribution networks and affects the power quality of the power supply.To adapt to the trend of large-scale grid-connected distributed generation and the increasing proportion of DC load,the development of AC/DC hybrid distribution networks has become an important direction of current distribution network research.In this thesis,the power flow calculation and operation optimization of AC/DC distribution networks with distributed energy are studied.The main work are as follows:Considering the various control modes and control strategies of the AC/DC converter,the steady-state analysis model of the converter is established.On this basis,combined with the typical AC/DC hybrid distribution system topology,the tidal current calculation model of the AC / DC distribution system with multiple types of distributed power is constructed.Considering the different control strategies such as master-slave control and droop control,a method of power flow calculation and loss analysis based on alternating iteration method is proposed.The method of power flow calculation and network loss analysis is verified by an 85-node AC/DC distribution network example system,and the effectiveness of the proposed method is verified by simulation results.Considering the multi-dimensional constraints of the operation of the AC and DC distribution network,aiming at the minimization of the system network loss,optimization analysis method of the operation of the AC and DC distribution network base on the genetic algorithm is proposed,which can obtain the optimal scheduling strategy of the converter in the day under the multi-dimensional constraints.The algorithm is programmed and implemented in the MATLAB platform,and the algorithm is verified by an example of a typical medium voltage AC/DC distribution network after the modified IEEE 33-node system.The operation optimization analysis of a multi converter AC/DC system under different DG penetration is carried out.The results of the example verify the effectiveness of the proposed operation optimization method of the DC distribution network.The example shows that the proposed method can effectively reduce the loss of the AC/DC system network and improve the operation economy of the system.