Abstract
This study aims to address the inherent uncertainty in plug loads and load extraction, distributed generation, and the inevitable circulating current in a parallel structure. Therefore, in this paper, an adaptive backstepping control scheme with an online parameter estimator (OPE) for a plug-and-play parallel converter system in a four-port power switcher is proposed. The adaptive backstepping control method was designed in the dq0 coordinate system to suppress the circulating current in the zero-component; the circulating current can be suppressed by using an embedded algorithm and omitting the extra controller. An adaptive update law was designed to weaken the influence of the arbitrary plug and extraction operations in the DC and AC buses to realize the plug-and-play function. The transient tracking performance is governed by the limitation of maximum total errors in the voltage and current. As a result, the settling times of the voltage, current, and power decreased. Additionally, to further improve the system robustness, an online inductance and resistance estimator was established using an optimal algorithm that solves the weighted least squares problem. In the estimator, there are no additional voltage and current sensors needed, and the mean squared error (MSE) of the estimation can be minimized. Simulation studies on a two-converter parallel system with a plug-and-play function were conducted using MATLAB/SIMULINK (R2018b, MathWorks, Natick, MA, USA) to verify the effectiveness of the proposed adaptive backstepping control strategy. The results show that this strategy improves system performance over that of a system with unbalanced parameters among a parallel structure with AC and DC system disturbances caused by arbitrary plug and extraction operations.
Highlights
Grid-tied distributed generation, microgrids, and variable loads are increasingly being utilized for power distribution
Two main challenges arise with the use of a plug-and-play parallel converter system in a four-port power switcher: (i) the transient performance is affected by unknown disturbances and arbitrary plug loads, load extraction, and distributed generation in both the AC and DC systems; (ii) the inevitable circulating current in the parallel structure reduces the rated transmission power and may damage the switching devices
Based on the aforementioned considerations, this study aims to develop an adaptive backstepping control strategy with an online system parameter estimator for a parallel converter system in a four-port power switcher
Summary
Grid-tied distributed generation, microgrids, and variable loads are increasingly being utilized for power distribution. Two main challenges arise with the use of a plug-and-play parallel converter system in a four-port power switcher: (i) the transient performance is affected by unknown disturbances and arbitrary plug loads, load extraction, and distributed generation in both the AC and DC systems;. Backstepping is a recursive Lyapunov-based scheme and often leads to better converter control performance [35] It is more flexible and does not force linearity in the designed system [36,37], which is suitable for the systems that suffer from unknown disturbances. Based on the aforementioned considerations, this study aims to develop an adaptive backstepping control strategy with an online system parameter estimator for a parallel converter system in a four-port power switcher.
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