The topology identification of low-voltage distribution networks is an important foundation for the intelligence of low-voltage distribution networks. Its accuracy fundamentally determines the effectiveness of functions such as power system state estimation, operational control, optimization planning, and intelligent electricity consumption. The low-voltage distribution network is composed of transformers, lines, and end users. The key task of topology identification is to distinguish the connection relationship between distribution transformers, low-voltage lines, and phase sequence with end users, which can be divided into transformer user relationship, line user relationship, and phase user relationship. At present, the main methods of low-voltage network topology identification can be divided into signal injection method and data analysis method. The signal injection method requires a large number of additional terminal devices and is difficult to promote. The data analysis method combines the characteristics of switch state, voltage, current, electrical energy, and other data to perform topology analysis. The commonly used methods include correlation analysis and feature learning. Finally, typical problems that urgently need to be solved in topology recognition and representation were proposed, providing a reference for the research and development of low-voltage distribution network topology automatic recognition technology.

In order to meet the operation requirements of the beam supply with multiworking conditions, multi-modes and high efficiency, a dual-mode hybrid output control method combining phase-shifting and pulse-width dual-mode modulation technology with secondary side series-parallel operation is proposed. In this paper, the structure and working mode of the new dual full-bridge topology are firstly analyzed. Secondly, the main circuit parameters are designed according to the power performance indicators, and the losses under two control modes of phase shift and pulse width are calculated. Finally, comparing the losses of these two control methods, and combining the series-parallel operation mode of the secondary side of the transformer, a dual-mode switching control method of the beam supply is designed. In order to verify the rationality of the dual-mode mixed output control method, a principle prototype with a rated capacity of 2 kW, a rated voltage of 1 800 V and a switching frequency of 50 kHz was used for verification. Experiments show the effectiveness and superiority of the dual-mode hybrid output control method.