Misoperation analysis and logic optimization of distance protection section I of polygonal impedance

Abstract

The widely used distance protection is of great significance to operation reliability of power grid. The paper cites an example of misoperation of distance protection section I and points out the defects of action zone configuration of polygonal impedance， namely the irrational resistance value due to load limit that leads to interphase impedance falling into distance protection section I and thus triggers misoperation during terminal faults. Therefore， the paper proposes a protection logic optimization scheme applicable to polygonal impedance elements： an independent load limit condition is set for distance protection section I for adaptive optimization of protection logic. Setting verification is performed， and fault playback is tested at the boundary of the optimized protection action zone. The rest results prove the feasibility of the optimal scheme. The case and optimal scheme mentioned above can serve as a reference for improving the reliability of distance protection that applies polygonal impedance elements.

Keywords

• polygonal impedance element
• distance protection
• load limit resistance