a new protection strategy for microgrid based on integration of active power index and fault current differential energy

The utilization of distributed generation (dg) sources in distribution systems has experienced significant growth due to their numerous advantages. despite benefits such as voltage support and reduced losses, dg integration has introduced substantial challenges to distribution system protection, impairing the performance of conventional protection schemes. variations in fault current levels, especially during islanding conditions, and bidirectional fault current flow are among the factors influencing the operation of traditional protection schemes. under such conditions, directional overcurrent relays may not operate as intended. moreover, coordinating multiple overcurrent relays is often challenging and can lead to increased operating times of protective relays. this paper proposes a directional comparison protection scheme for protecting lines and zones in active distribution systems based on the calculation of incremental active power transient energy. the proposed scheme is capable of detecting faults on microgrid lines at both low and medium voltage levels and is adaptable to changes in microgrid configuration. to prevent the directional protection scheme from operating during load switching transients, a differential protection scheme based on the calculation of transient energy of current signals is employed. the proposed methods offer the advantages of ease of calculation and high accuracy. an ac active distribution system incorporating inverter-based dg sources is implemented in the pscad-emtdc software to simulate various fault types. the simulation results are then transferred to matlab for the implementation of the proposed algorithms.