Power systems
Abbas-Ali Zamani
Abstract
The large-scale integration of renewable generation into microgrids can lead to decreased inertia, resulting in high rates of change of frequency and frequency instability. This issue is even more complex in islanded MGs that incorporate a high proportion of RGs and need to deliver power to loads in ...
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The large-scale integration of renewable generation into microgrids can lead to decreased inertia, resulting in high rates of change of frequency and frequency instability. This issue is even more complex in islanded MGs that incorporate a high proportion of RGs and need to deliver power to loads in islanded mode. To address this problem, a virtual inertia control scheme can be employed to enhance system inertia and maintain frequency stability. In this article, we propose a novel control strategy named the optimal nonlinear fractional-order PI-based virtual inertia controller, which integrates a nonlinear fractional-order PI controller into the conventional VIC loop. The designed ONFOPI+VI controller, which considers both inertia and damping properties, is optimized using the Coot optimization algorithm. Furthermore, an alternative control methodology, denoted as OFOPI+VI, has been developed to analyze and evaluate the outcomes obtained from the proposed ONFOPI+VI control structure. This paper compares the performance of the proposed ONFOPI+VI strategy to that of the OFOPI+VI and other VIC techniques for different RG and load variations under various scenarios. Simulation results and detailed analyses confirmed that the ONFOPI+VI controller significantly outperformed conventional methods, yielding at least a 30% improvement in IAE and a 20% improvement in ITAE compared to other control techniques.
Industrial Electronics
Mehran Jami
Abstract
In electric vehicles (EVs), the small size of the dc link capacitor results in significant voltage deviations when there are changes in load or uncertain fluctuations from the power resources. This causes a decline in voltage quality. To address the issue of low inertia, this study suggests the use of ...
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In electric vehicles (EVs), the small size of the dc link capacitor results in significant voltage deviations when there are changes in load or uncertain fluctuations from the power resources. This causes a decline in voltage quality. To address the issue of low inertia, this study suggests the use of a fast-responding energy storage system, such as a supercapacitor (SC), which can replicate inertial responses through a specified control algorithm. A virtual capacitor and a virtual conductance are presented in this paper, which are implemented in the inner loop control, specifically the current loop control of SC, to effectively emulate inertia and damping and improves the battery lifetime by reducing the rate of charge and discharge. To assess the stability of the EV, a comprehensive small-signal model is developed, and the acceptable range of inertia response parameters is determined through eigenvalues analysis of the system. Numerical simulations are conducted to demonstrate the performance of the proposed control structure.
Industrial Electronics
Mehran Jami; Qobad Shafiee; Hassan Bevrani
Abstract
In this paper, a virtual inertia control strategy based on linear feedback is presented that improves dynamic behavior of islanded dc microgrids interfaced with constant power loads (CPLs). In order to solve the stability challenges caused by low inertia and CPLs, the proposed control scheme is composed ...
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In this paper, a virtual inertia control strategy based on linear feedback is presented that improves dynamic behavior of islanded dc microgrids interfaced with constant power loads (CPLs). In order to solve the stability challenges caused by low inertia and CPLs, the proposed control scheme is composed of a virtual capacitor and a virtual conductance. It is implemented in the inner loop control, i.e. current loop control to be fast enough emulating inertia and damping concept. In addition, the droop characteristic is modeled by using the virtual resistance which adjusts the steady-state response of the system. In this study a multi-level structure is considered, which comprises the source level, interface converter level, and common load level. In addition, an accurate small-signal model is used to investigate the stability of dc MG interlaced with CPLs, and then, an acceptable range of inertia response parameters is determined by using the root locus analysis. Performance of the proposed control structure is demonstrated through numerical simulations.
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.
Power systems
Akbar Karimipouya; Shahram Karimi; Hamdi Abdi
Abstract
the main challenge in associate islanded Micro grid (MG) is the frequency stability due to the inherent low-inertia feature of distributed energy resources. That is why, energy storage devices, are utilized in MGs as the promising sources for grid short-term frequency regulation. Though energy storage ...
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the main challenge in associate islanded Micro grid (MG) is the frequency stability due to the inherent low-inertia feature of distributed energy resources. That is why, energy storage devices, are utilized in MGs as the promising sources for grid short-term frequency regulation. Though energy storage devices, improve the dynamic response of the load frequency control system, these devices increase system costs. Moreover, the modification or uncertainty of the system parameters will significantly degrade the performance of the conventional load-frequency control system. This article proposes the implementation of rotating-mass-based virtual inertia in Double-Fed Induction Generator (DFIG) to support the primary frequency control associated an adaptive Neuro-Fuzzy Inference System (ANFIS) controller, as the secondary frequency control. The simulation results illustrate that the suggested control scheme ameliorate the dynamic response and performance of the load frequency control system and also the studied islanded MG remains stable, despite severe load variation and parametric uncertainties.
