Method for identification of grid operating conditions for adaptive overcurrent protection during intentional islanding operation

Static Voltage Stability Analysis of an Islanded Microgrid Using Energy Function

“…The VSI mode is used for dispatchable generators (such as microturbines). Since the frequency and voltage are dependent upon the demand, the active and reactive powers generated at the unit (P gk and Q gk , respectively) are given by droop control equations, as depicted in (1) and (2) , which assumes that the distributed generators have an inductive output impedance [31]:…”

“…2) A particular VF bus K has active and reactive powers -Pgk and Qgk -calculated by (1) and (2), respectively. 3) The vector with the power mismatch equations (mismatch vector) is given by:…”

“…The growing concern related to the depletion of fossil fuels, the environmental effects of greenhouse gas emissions, and the low efficiency in transmitting large blocks of energy over long distances gave support to a new concept of energy systems, the microgrids. Microgrids are active low voltage or medium voltage AC or DC distribution systems [1] containing distributed generators and Energy Storage Systems (ESSs) that can operate connected to the main grid or in islanded mode [2]- [6]. Distributed generators technologies include wind turbines, photovoltaics (PVs), microturbines, combustion turbines, cogeneration, fuel cells, and reciprocating engines.…”

Robust Coordination Scheme for Microgrids Protection Based on the Rate of Change of Voltage

“…By using FCLs, the infeasibility of conventional DOCRs to provide proper protection coordination was overcome; however, the coordination is violated with any change in the network operating conditions. A thyristorbased scheme is proposed in [6] to identify a distribution system operating condition and adapt the overcurrent protection of the grid. In that scheme, the system equivalent impedance is estimated, which differs for islanded or connected-operating conditions.…”

Integration of wind turbines in distribution systems and development of an adaptive overcurrent relay coordination scheme with considerations for wind speed forecast uncertainty

“…In [9], an adaptive protection scheme in microgrids with PV units is proposed by analysing both three‐phase and double line‐to‐ground faults. The work in [10] proposed a methodology for identification of grid operating mode and used that to change the setting parameters of OC relays adaptively. The work in [11] proposed a fuse‐relay adaptive protection scheme that groups identical inverse‐time OC settings of relays and logic gates of circuit breakers to achieve better selectivity, reliability, and faster fault isolations.…”