Wind generator protection with ESSs considering grid connected and island mode operations

This paper proposes a novel scheme to protect a Wind Generator (WG) with Energy Storage Systems (ESSs). In the scheme, data are dealt with in an iterative way to obtain the relay coordination considering both generator operating modes: grid connected and island. The proposition relies on conventional protection functions adapted to the operational system requirements. A set of well-known protection functions (under-voltage, over-current, differential and unbalance) operating together in an innovative arrangement, was the main objective of this research. In order to validate the proposed scheme, a Wind Energy Conversion System (WECS) with a Vanadium Redox Flow Battery (VRFB) as an EES was implemented in a real time digital simulator (RTDS®) to perform hardware-in-the-loop simulations. The simulation system consisted of a Wind Generator with grounded stator connected to the system through a DC link in order to investigate its behavior subjected to internal and external faults. Very promising results considering the proposed scheme are presented.