Analysis and Simulation of Current-Only Directional Protection Incorporating Simple Communications

This paper presents a review of a range of novel protection schemes and described a new fault detection method using only current measurements, based upon comparison of pre- and during-fault current angles (and communication of angular shifts between measurement locations when faults are detected). Case studies are also presented to validate the effectiveness of the proposed method. The scheme is suitable for when conventional protection is not suitable for power networks, particularly microgrid with distributed generation units and energy storage leading to bi-directional power flows during normal and fault conditions, and low- and variable fault levels. In such cases, directional relays may be necessary to provide effective protection. However, measuring both voltage and current may be expensive and the scheme highlighted here overcomes such requirements, and it is proposed that 4/5G communications or radio-based communications may provide an effective means of transferring the (low-bandwidth) data when required.