New positive-sequence voltage detector for grid synchronization of power converters under faulty grid conditions

Abstract

This paper deals with a fundamental aspect in the control of grid-connected power converters, i.e., the detection of the positive-sequence component at fundamental frequency of the utility voltage under unbalanced and distorted conditions. Accurate and fast detection of this voltage component under grid faults is essential to keep the control over the power exchange with the grid avoiding to trip the converter protections and allowing the ride-through of the transient fault.In this paper, the systematic use of well known techniques conducts to a new positive-sequence voltage detection system which exhibits a fast, precise, and frequency-adaptive response under faulty grid conditions. Three fundamental functional blocks make up the proposed detector, these are: i) the quadrature-signals generator (QSG), ii) the positive-sequence calculator (PSC), and iii) the phase-locked loop (PLL). A key innovation of the proposed system is the use of a dual second order generalized integrator (DSOGI) to implement the QSG.For this reason, the proposed positive-sequence detector is called DSOGI-PLL. A detailed study of the DSOGI-PLL and verification by simulation are performed in this paper. From the obtained results, it can be concluded that the DSOGI-PLL is a very suitable technique for characterizing the positivesequence voltage under grid faults.

A Harmonic Current Detection Method for APF Under Unbalanced Voltage Condition Using Complex LMS Estimation

“…The parameters of PI controller in dqPLL can be found in [13]. As shown in this figure 4, the proposed complex LMS algorithm (represented by a red solid line) respond faster than other methods.…”

“…A comparative simulation among the proposed method, Kalman-filter-based [12] and dqPLL-based phase-estimation algorithms [13] is carried out to examine the effectiveness of the proposed method in this section.…”

Voltage Support Provided by STATCOM in Unbalanced Power Systems

“…To eliminate this harmonic, the 2nd order oscillation is removed from the measured by means of a band-pass filter centered at ω 0 = 2ω 1 . This filter is implemented with a Second Order Generalized Integrator for Quadrature Signal Generation (SOGI-QSG) [11], using the output in phase with the input since its transfer function behaves as a band-pass filter centered at ω 0 . This way, the dynamics of the mean value of the DC-link voltage is not altered.…”

“…This stage is formed by three "individual voltage controllers" in parallel, whose outputs are * , * and * , plus the calculation of * by means of Equation (11). This equation is obtained from Equation (10).…”

A Fast and Robust Grid Synchronization Algorithm of a Three-phase Converters under Unbalanced and Distorted Utility Voltages

“…Decoupled Double synchronous reference frame PLL (DDSRF PLL), Dual SOGI PLL (DSOGI PLL), and Three Phase Enhanced PLL (3phEPLL PLL) are also presented and their performances are analyzed comparatively. These methods show satisfactory performance under faulty grid conditions [9][10][11][12].…”