Research On Dynamic Power Flow Optimization Of Photovoltaic Electrical Highway Power Supply System

In recent years,with the concept of electrified highways,research on electrified highway power supply technology around new energy access has become a hot topic.Based on the analysis and comparison of photovoltaic power generation access to electrified highway power supply technology,this thesis studies the topology structure of traction power supply system of electrified highway and optimization of power flow distribution of power supply system.The main work includes:Firstly,the thesis conducts research on the topology structure of the new electrified highway power supply system under new energy access.By analyzing the characteristics of photovoltaic road test,hybrid energy storage and traction load,the traction power supply mode of the electrified highway is determined,and the self-consistent electrified highway AC/DC power supply system structure is constructed through the DC/DC converter access to the DC contact network and the VSC converter access to the AC power grid under the multi-energy complementary access of photovoltaic and energy storage systems.The mathematical modeling and calculation of the electrified highway traction power supply system and load are completed,laying the foundation for subsequent work.Secondly,in order to achieve safe,reliable and economical operation of the AC/DC hybrid traction power supply network,considering the randomness and volatility of the traction load,based on the mathematical model of the dynamic simulation of the DC network with multiple vehicles and the AC sub-system with VSC nodes,the node model of the AC/DC hybrid network is established.The static structure of the power supply system at a certain moment is scanned by the network scanning method,and the alternating iteration of the AC/DC hybrid power flow with multiple vehicle operation is solved by the Newton-Raphson method,and then the dynamic simulation is carried out to analyze the power flow distribution of the traction power supply system.The effectiveness of the model is verified by engineering examples.Furthermore,considering the impact of the randomness of photovoltaic power generation and traction load on power flow distribution,as well as the flow optimization of energy storage access,this thesis establishes the probability density function of the photovoltaic power generation system and traction load,and uses the improved Latin hypercube sampling as the basis for power flow calculation.On the basis of considering the constraints of load demand,photovoltaic and energy storage,and power balance with the higher-level power grid,a 24-hour stochastic optimal power flow model with the minimum network loss as the optimization objective is established,and an improved linearly decreasing particle swarm optimization algorithm(LDW-PSO)is proposed to solve the model.The case study and simulation show that the improved algorithm converges faster,and the optimized algorithm has smaller deviations in the probability density distribution and cumulative distribution of the expected node voltage of the AC/DC hybrid model,and the voltage fluctuation of the power supply system after energy storage access is lower,which can effectively reduce the system energy consumption.Combined with field data,the simulation model verifies the effectiveness of the above work,and the configuration of energy storage system can solve the problem of imbalanced supply and demand of distributed renewable energy from the spatial and temporal scales,providing a solution for the combination of clean energy and self-consistent electrified highways.