Research On Planning Model And Algorithm Of AC/DC Hybrid Distribution Network

With the development of the social economy,the requirements for quality of social power utilization are constantly increasing.Many problems have occurred in the traditional AC distribution network,such as the shortage of power supply corridors and large network losses.In recent years,with the widespread application of DG and advanced power electronics technology,the DC distribution network has developed rapidly.As the transition stage from the AC distribution network to the DC distribution network,the AC-DC hybrid distribution network provides new ideas for the development of the distribution network.Therefore,the AC-DC hybrid distribution network planning is of great significance.Firstly,the AC-DC hybrid distribution network is modeled,which mainly includes the topology of the distribution network,the three-phase unbalanced power flow model of the converter,the AC and DC sub-nets power flow model,the converter control strategy and operating constraints.Then,the symmetric component method is used to decompose the three-phase asymmetric structure.The system is modularized,and the converter is used as the boundary to realize the AC and DC sub-nets decoupling and alternating iteration method is used to calculate power flow.Finally,An AC/DC distribution network planning model which considers the randomness of bus and connection lines whether it is AC type or DC types is proposed.The Monte Carlo method is used to simulate uncertain output curves such as load demand and photovoltaic distributed power in the model.The planning scheme is divided into an upper-level planning model and a lower-level optimization model.The genetic membrane algorithm is used to calculate the construction and operating cost of the grid in the upper-level planning model and the lowest cost is the objective function.The interior point method is used in lower-level optimization model with the lowest operating cost as the objective function.The upper and lower models are solved alternately and iteratively to obtain the optimal configuration of the network.The analysis of the typical calculation examples which includes wind power,photovoltaic,and electric vehicle charging station shows that the proposed AC and DC distribution network planning method which considers the randomness of the AC and DC bus and connection lines meets the requirements of power balance and other operations under the restricted conditions,which will obtain a more economical planning scheme and provide a decision reference for the planning of AC and DC distribution networks.