A New Regional Protection Method for Active Distribution Networks in Multi-T-Connection Scenarios

In the context of the new power system, the intelligent upgrading process of distribution networks is faced with a complex scenario where high-penetration distributed generations (DGs) are integrated with the traditional network structure. Currently, in distribution networks, there are generally unmeasurable load branches between overhead line branch lines and ring main units. Meanwhile, the strong stochastic characteristics of DG output lead to the insufficient adaptability of traditional regional protection methods. In response to the above problems, this paper proposes a new regional protection method for active distribution networks suitable for multi-T-connection scenarios. Firstly, an equivalent model of DG considering output characteristics is constructed. On this basis, the amplitude, phase and frequency characteristics of current sequence components when a fault occurs in a distribution network with DGs are analyzed in depth, revealing the differences in fault characteristics of different sections. Based on this, a regional protection criterion for active distribution networks is proposed. The effectiveness of this scheme in scenarios with high-proportion DG integration and unmeasurable branch loads is verified by simulation. The research results show that this method can accurately identify fault sections, with high reliability and adaptability, providing new ideas for distribution network protection in new power systems.