Abstract
Microgrids active characteristics such as grid-connected or islanded operation mode, the distributed generators with an intermittent nature, and bidirectional power flow in active distribution lines lead to malfunction of traditional protection schemes. In this article, an impedance-based fault detection scheme is proposed as the main protection of microgrids by applying the proposed equivalent circuits for doubly-fed lines. In this scheme, relay location data and positive sequence voltage absolute value of the other end of the line are used. It can detect even high impedance faults in grid-connected and islanded modes. It is robust against load and generation uncertainties and network reconfigurations. Low sampling rate and minimum data exchange are among the advantages of the proposed scheme. Moreover, a backup protection scheme based on the conductance variations is suggested. No requirement for the communication link is a distinguished advantage of the proposed backup protection scheme. The proposed schemes have been simulated using PSCAD and MATLAB software and the results confirmed their validity.
Highlights
Distributed generators (DGs) interconnected to distribution networks form a type of power system called microgrid
Protection of line 4 is more difficult compared to others, because it to v-f for supporting voltage and frequency but because of PV system nature, it maintains is connected to the main grid and DG1 or in islanded upstream, and operation
Protection of line 4 is more difficult compared to others, because it is connected to the main grid and DG1 in upstream, and DG2 and DG3 downstream
Summary
Distributed generators (DGs) interconnected to distribution networks form a type of power system called microgrid. The frequency may change in the islanded part of the distribution grid because of active power imbalance In this case, coupling two asynchronously operating systems with active sources on both sides of one recloser by reclosing switch results in the failure of the attempt [4,5]. Fault detection using the communication link especially in the backup protection needs to communicate data with the adjacent lines which increases the volume of required data exchanges and costs. It does not operate in the link disconnection. Modified protection schemes according to microgrids behaviors are named protective strategybased schemes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
