A frequency locked loop strategy for synchronization of inverters used in distributed energy sources

Gain normalized adaptive observer for three-phase system

“…If the elements of the gain Matrix L are selected in a way such that l 2 + 1 ≥ l 1 ω n , then all the coefficients of polynomial (31) are non-negative. The stability of the polynomial (31) can be obtained through Routh-Hurwitz test.…”

“…Some of the techniques are: open or pseud openloop technique [5], frequency domain methods (e.g. dis-crete Fourier transform [6]), maximum-likelihood estimation (MLE) [7][8][9], singular-value decomposition (SVD) [10], linear and nonlinear least squares [11,12], linear and nonlinear phase-locked loop (PLL) [6,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], quadrature signal generator-based frequency-locked loops (FLL) [28][29][30][31][32][33], various variants of Luenberger observer [26,[34][35][36] etc.…”

“…As mentioned above, some of the direct phase estimation techniques are: linear and nonlinear harmonics oscillators (including various variants) [28,31,33], various variants of Luenberger observer [34][35][36]…”

Direct Power Control Based on Point of Common Coupling Voltage Modulation for Grid-Tied AC Microgrid PV Inverter

“…As a result, in addition to enhancing the stability robustness of VSIs, a limited bandwidth PLL is typically used, compromising the system's dynamic performance greatly. To circumvent the PLL system's limitations, some studies [23][24][25] proposed frequency locked loop (FLL)-based synchronization solution for the MG's VSI [23][24][25]. Power control approach based on PLL-less CCT is introduced in [26] for grid-tied hybrid MG's VSI.…”

Master-Slave Topologies with Phase-Locked Loops

“…PLL networks currently play an important role in precision electronic instrumentation [15], power distribution smart grids [16], computational clusters [17], and integrated circuits [14,17]. In all of these practical cases, isolated or networked PLLs are responsible for the correct recovering of time basis, synchronizing the processes.…”