Control
Amin Karimi; YousefReza Jafarian; Hassan Bevrani; Rahmatollah Mirzaei
Abstract
The use of renewable energy sources in microgrids has grown dramatically in recent years. The absence of a rotational mass in these microgrids and their interfaces leads to a lack of inertia and consequently, frequency and voltage instability. To cope with these dilemmas, the virtual synchronous generator ...
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The use of renewable energy sources in microgrids has grown dramatically in recent years. The absence of a rotational mass in these microgrids and their interfaces leads to a lack of inertia and consequently, frequency and voltage instability. To cope with these dilemmas, the virtual synchronous generator (VSG) has been introduced as an effective solution. This paper first focuses on modeling a VSG using basic electrical equations. It, then, proffers a transient fuzzy controller augmented on virtual inertia’s topology. Inspired by the FACTS’ performance, the privileged specifications such as STATCOM fluctuation damping ability for major perturbations at transient times are appended to the VSG scheme by a fuzzy controller. This controller is implemented with a feedback from the system voltage angle and its derivative, as well as in frequency and its derivative. The modified coefficients of both active and reactive powers are outputs of the fuzzy system. Using the proposed fuzzy controller, the transient response of VSG-based microgrids is improved. Simplicity and ability to improve the transient response are the principal specifications of the proposed configuration. Simulation results confirm the improvement of the presented method by the introduced augmented VSG control mechanism.
Control
YousefReza Jafarian; Amin Karimi; Hassan Bevrani
Abstract
Compared to individual DC or AC microgrids, the Hybrid microgrids (HMGs) are more efficient and inexpensive due to eliminating of multiple DC-AC-DC conversions. In HMGs, where AC loads are supplied by DC link, load demand disturbance has direct negative effects on the DC link voltage. In this study, ...
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Compared to individual DC or AC microgrids, the Hybrid microgrids (HMGs) are more efficient and inexpensive due to eliminating of multiple DC-AC-DC conversions. In HMGs, where AC loads are supplied by DC link, load demand disturbance has direct negative effects on the DC link voltage. In this study, primary and secondary controllers are applied to realize suitable operation conditions and control the microgrid converters. Each converter has primary controller to compensate the demand power fluctuations. The secondary controller is also designed for extra demand varieties and sends the proper control signals for primary controllers. The expressed capability of primary controllers can be obtained by designing a simple and robust secondary controller. Hence, the effects of demand fluctuations are eliminated and the system is stabilized. The overall state space model of system is conducted for stability analysis. To demonstrate the proposed controller efficiency, a prototype HMG is modeled and simulated. The stability analysis reveals that the system is stable when the secondary controller tracks the error signal of DC link. Simulation results show that the proposed method could efficiently manage the AC side voltage under load fluctuations.