Research On Optimization And Reconstruction Of DC Distribution Network And Fault Self-healing Algorithm

The advantages of the DC distribution network in terms of efficiency and power quality are gradually emerging.At the same time,it can be more convenient and economical to connect to the ever-expanding new energy distributed power generation,which will soon become the future solution to the insufficient power supply capacity of the urban power distribution system and improve the power However,due to the large fluctuations in the variable load power in the DC distribution network,when the converter power transmission margin is small,the converter transmission power can easily reach the limit,and the ability to respond to changes in the power flow is lost.Optimize the DC distribution network during operation and after a fault occurs,in order to realize the efficient use of electric energy.This paper uses the converter adaptive droop coefficient,network loss,and node voltage offset as the optimization goals to reconstruct and optimize the static grid structure of the DC distribution network and the faulty line after removal.The main research contents of the paper are as follows:(1)Analyze the advantages and disadvantages of different topological structures and wiring methods of DC distribution networks,clarify the applicable topologies and wiring methods in DC distribution networks,and analyze common equipment in DC systems such as voltage source converters,DC-The common types and common topologies of DC transformers are described,and the influence of different types of topologies on the operation of DC distribution network is obtained by comparison.(2)The power flow calculation model of the DC distribution network is studied,including the converter model when droop control is adopted,the DC-DC DC transformer model and the node types in the DC distribution network,and then the modified Newton Raphson algorithm is adopted.,Combined with the accurate loss model of the converter to calculate the power flow of the DC distribution network,obtain the node voltage,network loss and other indicators to prepare for the following optimization.(3)By studying the adaptive droop coefficient that characterizes the power transmission margin of the converter,combining the voltage of each node of the DC system and the network loss,using the method of membership function fuzzification,and using the Euclidean distance to integrate the three,and meet the requirements Under constrained conditions,the binary particle swarm algorithm is used to solve the optimal grid topology of the DC distribution network under static conditions.The modified IEEE33-node DC system verifies that the proposed method can obtain the network topology when the above three indicators are comprehensively optimal..(4)Based on the optimization algorithm proposed in Chapter 2,on the basis of analyzing the common fault types and fault characteristics of the DC distribution network,combined with the corresponding protection principle requirements of the DC distribution network,the DC system after the failure is processed,After the fault is removed,the DC power distribution system is restored and reconstructed in accordance with the hierarchical response,and finally achieves optimized operation under the goal of restoring as many loads as possible and switching times as few as possible.The modified IEEE33-node DC system is different.The reconstruction of failure recovery under this condition verifies the effectiveness of the proposed self-healing recovery strategy.