Comparison of Synchronization Techniques Under Distorted Grid Conditions

Abstract

In grid-connected power converter applications, the phase-locked loop (PLL) is probably the most widely used grid synchronization technique, owing to its simple implementation. However, in power grids some very common problems, such as voltage distortion, voltage unbalance, and frequency instability make synchronization a challenging task. The performance of the conventional synchronous reference frame PLL (SRF-PLL) is greatly reduced in the presence of distorted grid conditions. For a polluted grid some advance PLL techniques have been proposed, such as moving average filter PLL (MAF-PLL) and cascaded delayed signal cancellation PLL (CDSC-PLL). These techniques have been mostly evaluated in the presence of odd and even harmonics but the effects of interharmonics on these synchronization techniques still needs to be investigated. In this paper, a detailed performance comparison has been made between SRF-PLL, MAF-PLL, and CDSC-PLL for grid voltages contaminated with interharmonics in the presence of different grid disturbances, such as frequency jump, phase angle jump, and dc offset. The techniques are simulated using Matlab/Simulink. The CDSC-PLL shows excellent performance as compared with other techniques in terms of dynamic response as it settles to frequency step change in a half cycle but the presence of interharmonics greatly reduces its filtering capability. On the other hand, MAF-PLL gives a ripple free behavior in frequency estimation but with a much slower dynamic response as it settles to a frequency step change in more than three cycles. SRF-PLL only performs well under harmonics free grid voltages. INDEX TERMS Grid synchronization, phase locked loop, interharmonics and power quality improvement.

Enhanced Grid-Connected Phase-Locked Loop Based on a Moving Average Filter

“…Although the frequency and phase-angle steps rarely occur in real power grids, they may exist during the PLL startup. Moreover, these two cases are typically effective in verifying the dynamic performance of PLLs [3], [19], [21], [27]. To better demonstrate the effectiveness of the EMAF-PLL over these four testing cases, three other typical PLLs were also tested and compared with the EMAF-PLL, namely, a conventional SRF-PLL, a MAF-PLL based on a PI controller, and a MAF-PLL based on a PID controller (named MAF-PLL_PI and MAF-PLL_PID, respectively).…”

Frequency Adaptive Parameter Estimation of Unbalanced and Distorted Power Grid

“…delayed signal cancellation PLL (DSC-PLL) [17], cascaded DSC-PLL (CDSC-PLL) [18], repetitive learning-based PLL [19] to name a few. For a detailed review on three-phase grid synchronization techniques, [20], [21] and the references therein can be consulted.…”

Robust Gradient Estimator for Unknown Frequency Estimation in Noisy Environment: Application to Grid-Synchronization

“…Owing to the huge importance of grid synchronization technique, many results are available on this topic. Some popular grid synchronization techniques are: regression-based techniques [15]- [17], demodulation techniques [18]- [20], statistical methods [21], discrete Fourier transformation (DFT) [22], [23], adaptive observers [24]- [27], Phaselocked loop (PLL) [28]- [34], frequency-locked loop (FLL) [35]- [38], Kalman filtering [39], [40], self-tuning filter [41], [42], linear and nonlinear harmonic oscillator [43]- [45], open-loop technique [46], [47].…”

“…Phase locked-loop (PLL) [28]- [34] is undoubtedly the most popular technique available in the literature. Moreover, it has wider acceptability in the industrial applications as well.…”