A hybrid synchronous/fixed reference frame pll for phase synchronization with unbalanced three-phase grid conditions

Synchronous Reference Frame Phase Locked Loop (SRF PLL) has been widely used for synchronization three-phase grid-connected photovoltaic (PV) system. On the grid fault, SRF PLL distorted by negative sequence component and grid harmonic that caused an error in estimating parameter because of ripple and oscillation. This work combined SRF PLL with Dual Second Order Generalized Integrator (DSOGI) and filter to minimize ripple and minimize oscillation in the phase estimation and frequency estimation. DSOGI was used for filtering and obtaining the 90o shifted versions from the vαβ signals. These signals (vαβ) were generated from three phase grid voltage signal using Clarke transform. The vαβ signal was the inputs to the positive-sequence calculator (PSC). The positive-sequence vαβ was transformed to the dq synchronous reference frame and became an input to SRF-PLL to create the estimation frequency. This estimation frequency from SRF PLL was filtered by the low-pass filter to decrease grid harmonic. Moreover, the output of low-pass filter was a frequency adaptive. The performance of DSOGI PLL with filter is compared with DSOGI PLL, SRF PLL, and IEEE standard 1547(TM)-2003. The improvement of DSOGI PLL with filter gave better performances than DSOGI PLL and SRF PLLbecause it minimized ripples and oscillations in the phase and frequency estimations.

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Advanced Synchronous Reference Frame Controller for Three-phase UPS Powering Unbalanced and Nonlinear Loads

IEEE 36th Conference on Power Electronics Specialists, 2005. ◽

10.1109/pesc.2005.1581859 ◽

2006 ◽

Cited By ~ 4

Author(s):

Kyung-Hwan Kim ◽

Nam-Joo Park ◽

Dong-Seok Hyun

Keyword(s):

Reference Frame ◽

Nonlinear Loads ◽

Synchronous Reference Frame ◽

Three Phase

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A Neural Network Model of Flexible Spatial Updating

Journal of Neurophysiology ◽

10.1152/jn.00277.2003 ◽

2004 ◽

Vol 91 (4) ◽

pp. 1608-1619 ◽

Cited By ~ 24

Author(s):

Robert L. White ◽

Lawrence H. Snyder

Keyword(s):

Neural Network ◽

Reference Frame ◽

Spatial Information ◽

Target Location ◽

Target Position ◽

Spatial Location ◽

Spatial Updating ◽

Gaze Shift ◽

Fixed Reference ◽

Gaze Position

Neurons in many cortical areas involved in visuospatial processing represent remembered spatial information in retinotopic coordinates. During a gaze shift, the retinotopic representation of a target location that is fixed in the world (world-fixed reference frame) must be updated, whereas the representation of a target fixed relative to the center of gaze (gaze-fixed) must remain constant. To investigate how such computations might be performed, we trained a 3-layer recurrent neural network to store and update a spatial location based on a gaze perturbation signal, and to do so flexibly based on a contextual cue. The network produced an accurate readout of target position when cued to either reference frame, but was less precise when updating was performed. This output mimics the pattern of behavior seen in animals performing a similar task. We tested whether updating would preferentially use gaze position or gaze velocity signals, and found that the network strongly preferred velocity for updating world-fixed targets. Furthermore, we found that gaze position gain fields were not present when velocity signals were available for updating. These results have implications for how updating is performed in the brain.

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Mathematical Model of a Three-Phase Induction Machine in a Natural abc Reference Frame Utilizing the Method of Numerical Integration of Average Voltages at the Integration Step and Its Application to the Analysis of Electromechanical Systems

Mathematical Problems in Engineering ◽

10.1155/2019/4581769 ◽

2019 ◽

Vol 2019 ◽

pp. 1-13

Author(s):

Oleksiy Kuznyetsov

Keyword(s):

Reference Frame ◽

High Speed ◽

Numerical Models ◽

Second Order ◽

Integration Step ◽

Electromechanical Systems ◽

Suitable Alternative ◽

First Order ◽

Operation Speed ◽

Three Phase

Recent advances in the real-time simulation of electric machines are linked with the increase in the operation speed of the numerical models retaining the calculation accuracy. We propose utilizing the method of average voltages at the integration step (AVIS) for the design of a three-phase induction machine’s model in its natural abc reference frame. The method allows for avoiding rotational e.m.f. calculation at every step; in turn, the electromagnetic energy conversion is accounted by the change of flux-linkage. The model is integrated into the object-oriented environment in C++ for designing the computer models of electromechanical systems. The design of the model of an electromechanical system utilizing the proposed approach is explained in an example. The behavior of the numerical models of a three-phase IM has been compared for the set of conventional numerical methods as well as first- and second-order AVIS. It has been demonstrated that both first- and second-order AVIS methods are suitable tools for high-speed applications, namely, AVIS provides higher maximum possible integration step (e.g., first-order AVIS provides 4 times higher than the second-order Runge–Kutta method, and the second-order AVIS provides 2.5 times higher than the first-order method). Therefore, we consider the most preferable order of the AVIS method for the high-speed applications is the second order, while the first order may be a suitable alternative to increase the calculation speed by 30% with the acceptable decrease in the accuracy.

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