Improved Fault Phase Selection Scheme for Lines Terminated by Inverter Based Resources

With more renewable energy integrated to the grid in the form of inverter based resources (IBRs), traditional current-based fault phase selector encounters limitations. The causes of this problem are the weak infeed feature and variation of source impedance of IBRs. This paper proposes an improved fault phase selection scheme to solve this problem. Firstly, the reasons for the failure of traditional fault phase selection methods are analyzed. Then, compound proportion criterion including voltages and currents is established. The proposed criterion mitigates the effects of the weak-infeed feature and source impedance variation caused by IBRs. Finally, the corresponding improved phase selection method is proposed. The main advantages of proposed method are excellent adaptability and reliability. Numerical experiments prove the effectiveness of the proposed method.

I. Introduction

Phase selector is a key component of the protective relay, and its correct operation builds the foundation for automatic reclosing, protection, and fault location [1–2]. Nowadays, an increasing number of renewables are integrated to the grid in the form of inverter based resources (IBRs) [3–4]. The fault current characteristics of IBRs are quite different from those of synchronous generators. These factors present challenges to traditional protective relay systems, including fault phase selectors [5–6].