ARTICLE | doi:10.20944/preprints202110.0326.v2
Subject: Engineering, Electrical & Electronic Engineering Keywords: Cu2O; CIGS; HTL; Buffer Layer; SCAPS
Online: 22 June 2022 (10:09:49 CEST)
Copper indium gallium selenide (CIGS) is an inexpensive material that has the potential to dominate the next-generation photovoltaic (PV) industry. Here we detail computational investigation of CIGS solar cell with encouragement of adopting cuprous dioxide (Cu2O) as a Hole Transport Layer (HTL) for efficient fabricated CIGS solar cells. Although Cu2O as a HTL has been studied earlier for perovskite and other organic/inorganic solar cell yet no study has been detailed on potential application of Cu2O for CIGS solar cells. With the proposed architecture, recombination losses are fairly reduced at the back contact and contribute to enhanced photo-current generation. With the introduction of Cu2O, the overall cell efficiency is increased to 26.63%. The wide-band of Cu2O pulls holes from the CIGS absorber which allows smoother extraction of holes with experiencing lesser resistance. Further, it was also inferred that, HTL also improves the quantum efficiency (QE) for photons with large wavelengths thus increases the cell operating spectrum.
ARTICLE | doi:10.20944/preprints202110.0401.v1
Subject: Keywords: PV array configurations; Partial shading conditions; Performance assessment; Maximum Power Generation; Mismatch power loss; Relative power loss; Fill factor
Online: 27 October 2021 (11:32:30 CEST)
Partial shading on solar photovoltaic (PV) arrays is a prevalent problem in photovoltaic systems that impair the performance of PV modules and is responsible for reduced power output as compared to that in standard irradiance conditions thereby resulting in the appearance of multiple maximas on panel output power characteristics. These maxims contribute to mismatch power losses among PV modules. The mismatch losses depend on shading characteristics together with different interconnected configuration schemes of PV modules. The research presents a comparative analysis of partial shading effects on a 4 x4 PV array system connected in series(S), parallel (P), serries-parallel (SP),total-cross-tied (TCT),central-cross-tied(CCT),bridge-linked(BL),bridge-linked total cross-tied (BLTCT) ,honey-comb(HC), honey-comb total-cross-tied (HCTCT) and ladder (LD) configurations using MATLAB/Simulink. The PV module SPR-X20-250-BLK was used for modeling and simulation analysis. Each module is comprised of 72 number of PV cells and a combination of 16 PV modules was employed for the contextual analysis. Accurate mathematical modeling for the HCTCT configuration under partial shading conditions (PSCs) is provided for the first time and is verified from the simulation. The different configuration schemes were investigated under short-narrow,short-wide,long-narrow,long-wide, diagonal, entire row distribution, and entire column distribution partial shading condition patterns with mathematical implementation and simulation of passing clouds. The performance of array configurations is compared in terms of maximum power generated ), mismatch power loss (∆), relative power loss ) and the fill factor (FF). It was inferred that on average, TCT configuration yielded maximum power generation under all shading patterns among all PV modules interconnection configurations with minimum mismatch power losses followed by hybrid and conventional PV array configurations respectively.
ARTICLE | doi:10.20944/preprints202205.0194.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Solid state transformer; Direct current; Renewable Energy Systems; Ant Lion Optimizer
Online: 16 May 2022 (03:20:49 CEST)
The battle of currents between AC and DC reignited as a result of the development in the field of power electronics. The efficiency of DC distribution systems is highly dependent on the efficiency of distribution converter, which calls for optimized schemes for efficiency enhancement of distribution converters. Modular solid-state transformers play a vital role in DC Distribution Networks and Renewable Energy systems (RES).This paper deals with efficiency-based load distribution for Solid State Transformers (SSTs) in DC distribution networks. Aim is to achieve a set of minimum inputs that are consistent with output while considering constraints and efficiency. As the main feature of modularity is associated with a three-stage structure of SSTs. This modular structure has been optimized using Ant Lion Optimizer (ALO) and validated by applying it EIA (Energy Information Agency) DC Distribution Network which contains SSTs. In the DC distribution grid, modular SSTs provide promising conversion of DC power from medium voltage to lower DC range (400V). The proposed algorithm is simulated in MATLAB and also compared with two other metaheuristic algorithms. The obtained results prove that the proposed method can significantly reduce input requirements for producing the same output while satisfying the specified constraints.
ARTICLE | doi:10.20944/preprints202205.0204.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: microgrid; DNN; parallel inverters; island mode; power quality
Online: 16 May 2022 (10:13:15 CEST)
The microgrid is a small-scale, autonomous decentralized power plant with its own distributed generation, storage capacity and multiple loads, with the capacity to function in grid interconnected and an island mode. The decentralized control of microgrids with parallel operated voltage source converters (VSCs) is proposed in this paper to improve power quality using a machine learning approach. The DNN based MPPT controller is proposed and its best performance is presented. The SRF-PLL is utilized for AC side synchronization in VSC control. The proposed microgrid involves two PV arrays fed to two voltage source converters along with their independent controls, connected in parallel through LC filters and line coupling transformers and serves the loads at PCC. The proposed model is simulated using MATLAB/Simulink. The dq-framed inner loop control is employed to individually regulate the real and reactive power at the point of common coupling. Furthermore, the proposed model is analyzed and compared by employing a mathematical model of AC system dynamics, inner loop control, output voltage quality, AC harmonic spectrum analysis, and total harmonic distortion (THD) in both grid interconnected and island mode. In island mode, AC harmonic spectrum and THD are accomplished within the permissible range.
ARTICLE | doi:10.20944/preprints202207.0104.v2
Subject: Materials Science, Nanotechnology Keywords: Double Absorber Layer Solar Cell; Recombination; Numerical Investigation
Online: 12 October 2022 (05:46:07 CEST)
Herein we foremost detailed the numerical modeling of the double absorber layer- methyl ammonium lead iodide– carbon nitride layer solar cell and subsequently provided in-depth insight on the active layer associated with dominant radiative and non-radiative recombination losses limiting the efficiency ( ) of the solar cell. Under recombination kinetics phenomena, we explored the influence of Radiative recombination, Auger recombination, Shockley Read Hall recombination, the energy distribution of defects; Band Tail recombination (Hoping Model), Gaussian distribution, metastable defect states including single donor (0/+), single acceptor (-/0), Double Donor (0/+/2+), double acceptor (2/-/0-), and the interface layer defects on the output characteristics of the solar cell. Setting defect (or trap) density to with uniform energy distribution of defects for all the layers, we achieved the of 24. 16 %. A considerable enhancement in power conversion efficiency was perceived as we reduced the trap density to for the absorber layers. Further, it was observed that for the absorber layer with double donor defect states, the active layer should be carefully synthesized to reduce crystal order defects to keep the total defect density as low as to achieve efficient device characteristics
ARTICLE | doi:10.20944/preprints202204.0275.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Voltage Regulation (VR); Distributed Generation (DG); Renewable Energy Sources (RES); Voltage Regulation (VR); Ancillary Service
Online: 28 April 2022 (08:36:36 CEST)
Voltage Stability & Control, is very crucial compared to other Power System (PS) Quality and Stability issues. Long-Vertical-Power-Flows in Conventional Grids, causes voltage drops which in turn causes huge power losses, especially in the Medium Voltage (MV) and Low Voltage (LV) Distribution Networks. Such technical losses in abysmally-planned weak distribution networks, lead to substantial loss of revenues to the utility grid. Apart from classic Voltage Regulation (VR) techniques, with the rise of Distributed Generation (DG) based on Renewable Energy Sources (RES), Horizontal-Power-Flows can be introduced in the network, through various Smart Grid techniques. Coupling such sources, near load centers shall mitigate long flows from expensive conventional sources at times of huge demands, improving feeders’ Voltage Profile. This Ancillary Service of Voltage Support from DG RESs shall thereby alleviate revenue losses caused by long-power-flows in weak distribution grids. For a developing country like Pakistan, loss of revenue from an already expensive utility gives huge blow to the economy. So, a similar technique for voltage support is proposed for an 11-kV feeder, which faces similar problem, and the results are remarkable. The technique is implemented using OpenDSS Tool by modelling 3MWp PV Penetration along with some future storage.
ARTICLE | doi:10.20944/preprints202205.0151.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Sensitivity Analysis; DC distribution networks; DC vs. AC; efficiency; load modeling; Renewable Energy Sources; Monte Carlo
Online: 11 May 2022 (09:03:24 CEST)
The new millennium has witnessed a pervasive shift of trend from AC to DC in residential sector. The shift of trend is predominantly due to independent residential solar PV systems at rooftops and escalating electronic loads with better energy saving potential integrated with diminishing prices as well as commercial availability of DC based appliances. DC has ousted AC in generation, transmission, and utilization sectors with the advent of DC based generating systems (e-g solar PV), high voltage DC (HVDC) transmission and the utilization of DC based loads respectively. However, the war of currents (AC vs DC) is still ON as regards to distribution sector. Efficiency is the parameter that once wiped DC out of the power systems scenario as compared to AC-at the time of Tesla and Edison. Therefore, the same parameter is utilized to determine which is better for distribution sector under current conditions; AC or DC? A comprehensive sensitivity analysis considering real load profile is missing in the present body of knowledge. In order to fill that gap, this paper is an attempt to include comprehensive sensitivity analysis of DC distribution system and its simulation-based comparison with AC counterpart considering real load profile. The paper uses Monte Carlo technique and probabilistic approach to add diversity in residential loads consumption and in turn to obtain instantaneous load profile. The paper also presents a futuristic perspective of power electronic converter (PEC) efficiency variation on the efficiency comparison of both AC and DC distribution systems. Since the present body of knowledge generally compares AC and DC distribution based upon assumptions and limited scenarios which results in conflicting outcomes; in contrast, the discoveries of the current examination are useful to reduce the confusions and conflictions regarding which is better at distribution scale; AC or DC?