Joint Generarion For Multi-Node Loads And Voltage Stability Analysis Of Distribution Network With Electric Vehicle

The energy transition strategy and smart city construction have led to the further application and popularization of electric vehicles,and the existing charging facilities cannot meet the rapidly growing demand for electric vehicle charging.At the same time,the random charging behavior of electric vehicles makes the charging load has a complex correlation with the transportation network and distribution network.Accurate analysis of the impact of strong random charging load on voltage stability and operation reliability of distribution network after large-scale electric vehicle access is an important basis for distribution network expansion planning and charging facilities construction.It’s also an urgent problem to be solved in the process of electric vehicle popularization.To solve this problem,we need to start from three aspects.The first aspect is that we need to know the coupling characteristics between electric vehicles and traffic network and distribution network.The second aspect is to deeply mine the time-space characteristics of strong random charging load.The third step is to identify the weak links in the distribution network.Therefor,a method that joint generation for multi-nodes loads and voltage stability analysis of distribution network with electric vehicle is proposed.In order to accurately mine the spatiotemporal characteristics of electric vehicle distribution network load,a generation model of charging load and conventional load is established.For electric vehicle charging load,the first step is to analyze the coupling relationship between charging load and traffic network and distribution network,and establish a "road-network" coupling network.The second step is to build a closed-loop travel chain model considering the correlation between destination type and time based on the statistical analysis of user travel characteristics.The third step is to realize user random travel simulation through Monte Carlo simulation,generate massive potential charging load scenarios,fully tap the time-space characteristics of charging load,and screen out typical and extreme charging load scenarios.For conventional loads（loads other than electric vehicle charging load in distribution network）,the first step is to analyze the spatial correlation between conventional load nodes through Pearson correlation coefficient.The second step is to consider the impact of date type on conventional load,establish a joint scenario generation model of multi node conventional load of distribution network based on conditional Wasserstein gradient penalty generation countermeasure network,and generate a large number of potential conventional load scenarios.The third step is to screen out typical and extreme conventional load scenarios.In order to effectively analyze the voltage stability of distribution network after electric vehicles are connected,we need to master a comprehensive load scenario.The first step is to screen scenarios based on clustering algorithm to determine different typical and extreme charging scenarios and typical and extreme conventional load scenarios.In the second step,the charging load scenario is superimposed with the conventional load scenario,and multiple load scenarios including potential low probability extreme load scenario and potential typical scenario are constructed.The third step is to analyze the voltage stability of distribution network under multiple scenarios through fast voltage stability index and voltage stability margin,and identify the weak nodes of distribution network.Based on the improved IEEE 33 bus model,an example analysis is carried out with the actual traffic network in China as the research object.The results show that the charging load generation model established in this paper can effectively represent the randomness of user travel.At the same time,the simulation effect is more real than the traditional model.The conventional load generation model can fully mine the time-space correlation and probability characteristics of conventional load.It also has good coverage ability of unknown scenes.The proposed voltage stability analysis method can effectively analyze the overall and local impact on the voltage of the distribution network after the disordered charging load is connected.It also accurately identify the potential weak links of the distribution network.Meanwhile,it can provide a reliable decisionmaking basis for the expansion of the distribution network and the construction of charging facilities.