Wind power plants are playing an important role in renewable energy generation in this decade. With the enhancements in its technology, mainly based on the aggregation of power electronics, many studies have been carried for evaluating their impact in power quality. Although the Brazilian Electrical System National Operator, who is responsible for transmission and generation system management, has suggested a procedure for such studies, there are many aspects related to the simulation algorithm and the electrical components modelling that are left aside from the problem, without an adequate reasoning of its impacts on power quality simulation results. This paper presents a detailed analysis of a wind farm impact on the Brazilian distribution system power quality. Both internal (wind park elements) and external (power grid) components modelling effects on harmonic propagation are considered, and these effects are evaluated
This work presents a novel solution for magnetic field calculation in two-dimensional problems in which one region is defined with space-varying magnetic parameter. The proposed solution extends the well-established Maxwell-Fourier method for calculating magnetic fields in surface-mounted cylindrical high-speed permanent-magnet machines. This contribution is effective to evaluate more realistic magnetic parameters, where measurements of a high-speed permanent-magnet generator prototype indicate saturation in the retaining sleeve due to pole-to-pole leakage flux. The saturation profile is a function of mechanical angle and can be modeled with the aid of a space-varying relative permeability, expressed in terms of a Fourier series. As an example, the presented solution has been applied to a surface-mounted PM machine at no-load condition. Magnetic field calculations show that a simple saturation profile, with low order space-varying permeability in the retaining sleeve significantly affects the magnetic flux density distribution in the air-gap. The analytical solution is confronted with finite-element method, which confirms validity of the proposed methodology.The available literature on (semi-)analytical technique for PM machine evaluation is extensive, with published papers ranging over twenty-five years, to the best of the authors' knowledge [10][11][12]. Moreover, there is still great effort towards methods with better accuracy and less restricting assumptions [4,[13][14][15][16][17][18][19][20][21][22] to list a few recently published works. Dubas et al. [23] realized an overview on the existing (semi-)analytical models in Maxwell-Fourier methods (vis., multi-layer models, eigenvalues model, subdomain technique and hybrid models) with the effect of local/global saturation. Further details, advantages and disadvantages of these techniques can be found in [23][24][25]. Ramakrishnan et al. [13] presented a comprehensive comparison of analytical methods, where a subdomain technique exceeded the others in terms of accuracy with reasonable calculation time.Furthermore, extending the limitations discussed in [25], recent developments include more realistic geometric structures, such as tooth-tips [14][15][16][26][27][28] or rotor eccentricity [27,29]. Chebak et al. [30] and Rahdeh et al. [31] defined more realistic magnetic parameters, but in slotless topologies. Qian et al. [29] and Ortega et al. [32] evaluate several geometries and physical imperfections expected from manufacturing processes. Spranger et al. [33] and Dubas et al. [23,24] have recently developed new techniques to account for finite soft-magnetic permeabilities, respectively: (i) in the multi-layer model using the Cauchy's product theorem [33], and (ii) in the subdomain technique by applying the superposition principle in both directions [23,24]. As discussed by Hannon et al. [34], both methodologies are very effective since they enable the magnetic field calculation in the ferromagnetic material of slotted geometries. The subdomain technique has be...
Reliability is an important issue related to the modular multilevel converter (MMC)-based medium voltage (MV) drives. The design for reliability (DFR) approach has been discussed in many power electronic systems in recent years. MMC-based MV drives power losses and thermal cycling are strongly affected by start-up and low-speed operation, since zero-sequence current injection must be applied. In order to implement fast thermal simulations, the traditional DFR approach does not consider the heat sink thermal capacitance, which can significantly affect the MMC lifetime prediction. This article discusses how the heat sink realisations (material, thickness) affect the MMC-predicted lifetime and evaluates how the drive start-up time affects the damage in the power converter. The case study is based on a 1.4 MW slurry pump system driven by a three-phase induction motor. The lifetime evaluation of the MMC is realised through the Monte-Carlo simulation. The results show that the traditional approach results in an underestimation of up to 42.5% of the converter lifetime. In addition, long start-up times lead to a longer lifetime when compared to the shorter start-up times, due to the reduced thermal stresses in the semiconductors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.