###### Abstract  
As the strategic position of distributed photovoltaic (PV) power generation in multi-level distribution networks continues to rise, its impact on the stable operation of the grid is becoming increasingly significant. This study delves into the influence of two key factors, the integration location and penetration rate of PV systems, on the distribution and flow of energy and the steady-state performance of multi-level distribution networks. Based on this, the study proposes a simplified grid analysis framework for analyzing and optimizing the energy allocation strategy of distribution systems and develops a PV configuration strategy aimed at optimizing the energy planning and design process of engineering projects. Taking a typical PV-participating distribution system as an example, the study provides a detailed description of the typical three-layer distribution network structure and deduces the relationship of the PV, node voltage, and node voltage deviation. The study verifies the accuracy and practical value of the proposed simplified framework through real-time monitoring simulation of node voltages and line losses. Finally, to achieve optimal energy allocation, the study proposes a PV segmentation strategy applied to the system and compares it with the traditional reactive power control strategy, demonstrating the advantage of the strategy in improving the system's clean energy ratio and reducing network losses. This paper's research on the impact of PV systems and the proposed simplified theory for distribution networks is universally applicable, and it holds significant reference value for practical engineering design. PV power system; islanded operation; energy optimal configuration; multi-level distribution network; data analysis 2020 IEEE/RSJ International Conference on Intelligent Transportation Systems (ICRS), Vol., pp. 2018-2018  
The grid-connected PV system refers to the injection of the electricity generated by the PV generation system into the utility grid. With large-scale solar energy being integrated into the micro-grid, the PV power supply may contribute more than 50% of the system's total generation. However, it should be noted that, in order to accommodate such a high penetration of PV power supply, the conventional synchronous generators will be reduced, leading to problems of insufficient system inertia and voltage support capability [3]. Detailed studies concerning the power quality due to the intermittent nature of the PV energy generation and grid operation of these generators can be seen in [4] and [5]. Meanwhile, if the distributed PV power sources with different penetration rates are installed in different locations of the power network in different ways, it can also cause serious problems, e.g., the large deviation of node voltage, line overload, and three-phase imbalance [6; 7; 8], and it can even affect the safety of the transformer (TR). Due to the randomness, volatility, and intermittency of the output of the PV power supply, the power network will fluctuate significantly or even become unstable. For example, in [9], the issue of the unexpected overloading of a PV grid was investigated for household appliances, proving the rise of the voltage in the period of peak power generation; in [10], the involved environmental conditions such as the passing clouds were also proven to cause intensive voltage fluctuations of grid-connected PV systems. Therefore, how the PV access point and PV penetration rate affect the safety, transient, and steady performances of grid-connected PV systems is an important but challenging issue to be addressed. But, unfortunately, most research work only focuses on one special case when investigating this issue [11; 12; 13]. For the grid-connected PV system, the special situation of islanded operation is characterized by randomness, unpredictability, and great destructiveness. Islanding refers to a phenomenon that occurs when the local demands of an area are supplied by PV power sources under a utility grid outage condition [14].