36 / 2024-03-29 14:59:32

Study on Traveling Wave Characteristics of Arc Grounding Fault in Hybrid Distribution Network with Distributed Generation

hybrid distribution network,distributed generations,traveling wave,arc grounding fault

In order to adapt the needs of society, the structure of urban medium and low voltage distribution network has been continuously developed and improved. On the one hand, power cables are put into use in distribution networks, and traditional overhead distribution lines are gradually replaced by hybrid lines of overhead lines and cables. On the other hand, in the background of “carbon neutrality” target, a large number of distributed generations (DGs) connected to the power grid. Therefore, this paper establishes a hybrid distribution network with photovoltaic power generation system and energy storage system, and studies the influence of different types of DG on the characteristics of traveling wave in hybrid lines of cables and overhead lines while arc grounding fault occurs. First of all, building a hybrid distribution network of overhead lines and cables with EMTP software, the topology structure of hybrid distribution network is shown in Fig. 1. While the single-phase arc grounding fault occurs at point F of line L₂ at 0.1 s, the traveling wave measured at point 1 is shown in Fig. 2. Due to the different wave impedance of overhead lines and cables, the line traveling wave transmission characteristics of hybrid lines are different from pure overhead lines or cable lines. Besides, the transmission characteristics of current and voltage travelling waves of different grounding faults can be obtained and analyzed. Secondly, the principle and control mode of photovoltaic power generation system and energy storage system are briefly introduced. A typical photovoltaic power generation system model is established, as shown in Fig. 3, including photovoltaic arrays, DC/DC converter, external equivalent load and so on. Among them, the output characteristics of photovoltaic array will vary with the change of sunshine intensity or ambient temperature. A battery energy storage system model is also established, as shown in Fig. 4, in which the Buck-Boost DC/DC bidirectional converter is selected as the voltage conversion device to meet the needs of bidirectional power flow caused by battery charging and discharging. Thirdly, the above DG components is connected to the hybrid distribution network and their influence on the fault traveling wave characteristics are analyzed. When the arc grounding fault occurs in the hybrid distribution network, the DG components may affect the amplitude, polarity, frequency, steepness of wave head, and some other characteristics of traveling wave, meanwhile, the nonlinear characteristics of the power electronic equipment may affect the identification of the traveling wave head. Finally, the influence of DG on traveling wave characteristics in hybrid distribution network while arc grounding fault occurs is summarized and based on above research, some suggestions of using traveling waves to detect arc grounding fault is put forward.