The industry of solar photovoltaic (PV) energy and its application is still booming to enhance the sustainability of the society. When PV systems are connected to the grid, challenging issues should be addressed. One of the challenges is related to interharmonics in PV systems, especially with a large-scale adoption of PV systems. However, the origins of interharmonics remain unclear, although the impact of interhamonics has been reported in the literature. Thus, this paper explores the generation mechanisms of interharmonics in PV systems and the characteristics. The exploration reveals that the perturbation from the maximum power point tracking (MPPT) algorithm is one of the origins of interharmonics appearing in the grid current. Accordingly, the MPPT controller parameters such as the perturbation step size and the sampling rate have an inevitable impact on the interharmonic characteristics. Furthermore, an approach to characterize the interharmonics in the grid current is proposed. With the proposed model, interharmonics can be predicted according to the designed controller parameters in terms of frequencies and amplitudes. Experimental tests are performed on a single-phase grid-connected PV system. The results are in a close agreement with the analysis and, thus, validate the effectiveness of the proposed model. Index Terms-Interharmonics, inverters, maximum power point tracking (MPPT), modeling, photovoltaic (PV) systems, power quality.
I. INTRODUCTIONI N RECENT years, more and more photovoltaic (PV) systems have been installed and connected to the grid due to the increasing demand of greener and more sustainable energy systems. However, at the same time, massive connections of PV systems to the grid bring several challenges, e.g., power quality and grid stability issues [1]-[6]. It has been reported that the
Mining is an important industry in many countries including Australia and plays a vital role in their economy. The industry heavily depends on electricity as it employs different types of electrical loads. Consequently, a stable and reliable supply of electricity is vital for running the production smoothly. In this review paper, electrical characteristics of mining power systems are described and common power quality and energy efficiency concerns in these systems are stated and classified. Different types of common power electronics topologies used in the industry are also studied and main requirements for reliable and robust operation of the system are categorized. A comprehensive case study to elaborate power quality challenges in mining distribution network is performed.INDEX TERMS Distorted grid, distribution network, energy efficiency, mining industry, power quality, power system robustness.
Current and voltage source Adjustable Speed Drives (ASDs) exert distortion current into the grid, which may produce some interharmonic components other than the characteristic harmonic components. This paper studies the effects of passive components on the input current interharmonics of adjustable speed drives with and/or without motor current imbalance. The investigation is done at different motor operating frequencies and load torque values. It shows that selecting the small filter components (AC choke, DC choke and DC-link capacitor) results in different performances in respect to those interharmincs issued by motor current imbalance and other non-characteristic interharmonics. The results are helpful for engineers investigating the effects of drive filters on the input current interharmonic components. Index Terms-Adjustable speed drive, passive component effects, interharmonics, harmonics, balanced and unbalanced load.
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