## 1 Introduction  
Residual current protection plays a crucial role in earth (leakage) fault detection and protection technology within low-voltage distribution networks [1, 2]. However, it is susceptible to influences from line distribution capacitance current and load fluctuation factors [3, 4]. The detection of faults by residual current protection primarily relies on analyzing the power frequency amplitude, phase angle, and phasor changes of the residual current at the measurement point. The amplitude comparison method criterion is limited by the presence of inherent residual current during normal operation, leading to a protection dead zone [5, 6]. The current pulse method relies on detecting sudden changes in the residual current amplitude for fault assessment. However, due to the unpredictable nature of fault current phase angles, a considerable protection dead zone exists. On the other hand, the phase and amplitude detection method assesses faults based on changes in the residual current amplitude and phase angle. Although effective in theory, the complexity of calculations often leads to protection migration and rejection issues in practical applications, resulting in less-than-ideal protection outcomes [7]. In contrast, the current separation method focuses on transient and steady-state characteristics of electric shocks. By isolating the electric shock current from the residual current and making judgments based on the electric shock current, this method successfully eliminates the protection dead zone. Currentseparation stands out as a primary research approach for electric shock protection [8; 9; 10; 11]. During leakage faults in electrical equipment, the residual current exhibits non-sinusoidal characteristics, impacting the performance of Residual Current Devices (RCDs) [12; 13]. Additionally, the increasing use of diverse power electronic equipment complicates the harmonic features of the inherent residual current, posing challenges for traditional leakage protection methods that rely on amplitude, phase angle, or time-frequency characteristics of residual current [14]. Significant magnitudes of residual current can render general and intermediate protection mechanisms inoperative, particularly in TN configurations with repeated grounding, highlighting the need for innovative solutions in electrocution protection research [15; 16]. The inherent residual current in the low-voltage distribution network primarily originates from concentrated loads at the line's ends and branches. The earthing point in TN configurations is typically situated at the user-side measuring box or electrical equipment, with the loop that amplifies residual current also located at the terminal load. Consequently, the actual inherent residual current in front of the user-side measuring box is minimal, allowing for the logical division of the protection range into distinct closed sections. The inherent residual current in these sections is significantly lower than that measured by general and intermediate protection devices installed on equipment, presenting an opportunity to enhance protection sensitivity. However, a challenge arises in selecting the closed sections. The need to isolate repeated earthing points of TN configurations outside these sections poses a significant challenge. This isolation is crucial for overcoming the limitation of installing residual current protection in TN configurations, thereby enhancing the safety of such configurations. Addressing this challenge is essential for improving the overall safety and effectiveness of protection measures in low-voltage distribution networks. Through an in-depth examination of the residual current generation mechanism in low-voltage distribution networks, this study introduces a novel distributed residual current protection approach based on the closed-section method. This research delves into the impact of inherent residual current and the presence of repeated earthing in TN configurations on residual current protection functionality.