Abstract
Voltages sags have become the major issue that prevents the customers from getting high-quality power supply, and the dynamic voltage restorer (DVR) is considered an effective way to solve this issue. In this work, a method for voltage sag detection implemented in the time-domain is firstly addressed, which features highly accurate and fast response. Then, the dual-loop voltage–current control for the DVR is intensively investigated. Specifically, the optimal tuning of the inner current loop to achieve the maximum active damping is approached, and the voltage controller implemented in the discrete-time is developed. Tuning of the voltage loop based on critical damping is also approached, which features reduced settling time and avoidance of overshoot. The simulation and experimental results have verified the effectiveness of the proposed method for detection and management of voltage sags.
Highlights
It has been reported that according to the statistics, voltage sags, which can cause enormous economic loss every year, account for over 70% of the cases that give rise to the power-supply deterioration, resulting in severe complaints from the customers (Nagata et al, 2017; Parreño Torres et al, 2019; Han et al, 2020)
Among the proposed methods, the dynamic voltage restorer (DVR), which is connected between the grid and the load, has been commonly considered an effective and economical way to solve the issue of voltage sags, and a high-quality power supply can be expected
The fast and accurate voltage sag detection and the effective voltage regulation strategy are of almost importance to the DVR to achieve a high level of performance
Summary
It has been reported that according to the statistics, voltage sags, which can cause enormous economic loss every year, account for over 70% of the cases that give rise to the power-supply deterioration, resulting in severe complaints from the customers (Nagata et al, 2017; Parreño Torres et al, 2019; Han et al, 2020). It has been addressed that the single-loop voltage control method suffers from the issues of poor stability and constrained loop-bandwidth, which can result in an oscillatory and slow transient response of the output voltage This approach is not preferred for high-performance applications, it has the merits of simple structure and easy implementation. The frequency response analysis is employed in these studies, where the bandwidth of the voltage loop is tuned to be onefifth to one-tenth of that of the current loop, which is a rule of thumb for a common dual- or multi-loop control structure for grid-following converters This rule is not applicable for the dual-loop regulated DVR, since the objective of the current loop is to improve damping, instead of signal tracking where bandwidth is concerned.
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