Open Access. Powered by Scholars. Published by Universities.®
- Publication
- File Type
Articles 1 - 7 of 7
Full-Text Articles in Engineering
Prediction Of Remaining Life Of Power Transformers Based On Left Truncated And Right Censored Lifetime Data, Yili Hong, William Q. Meeker, James D. Mccalley
Prediction Of Remaining Life Of Power Transformers Based On Left Truncated And Right Censored Lifetime Data, Yili Hong, William Q. Meeker, James D. Mccalley
James McCalley
Prediction of the remaining life of high-voltage power transformers is an important issue for energy companies because of the need for planning maintenance and capital expenditures. Lifetime data for such transformers are complicated because transformer lifetimes can extend over many decades and transformer designs and manufacturing practices have evolved. We were asked to develop statistically-based predictions for the lifetimes of an energy company’s fleet of high-voltage transmission and distribution transformers. The company’s data records begin in 1980, providing information on installation and failure dates of transformers. Although the dataset contains many units that were installed before 1980, there is no …
End-To-End Modeling For Variability And Reliability Analysis Of Thin Film Pv, Sourabh Dongaonkar, Muhammad Alam
End-To-End Modeling For Variability And Reliability Analysis Of Thin Film Pv, Sourabh Dongaonkar, Muhammad Alam
Sourabh Dongaonkar
We present an end-to-end modeling framework, spanning the device, module and also system levels, for analyzing thin film photovoltaics (PV). This approach is based on embedding a detailed, statistically relevant, physics based equivalent circuit into module and array level simulations. This approach enables us to analyze key variability and reliability issues in thin film PV, and allows us to interpret their effect on process yield and intrinsic module lifetimes. Our results suggest that the time-zero gap between cell and module efficiencies, a key variability concern for thin-film PV, can be attributed to processrelated shunts with log-normal PDF distributed randomly across …
A Physical Model For Non-Ohmic Shunt Conduction And Metastability In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Y, Souvik Mahapatra, Muhammad Alam
A Physical Model For Non-Ohmic Shunt Conduction And Metastability In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Y, Souvik Mahapatra, Muhammad Alam
Sourabh Dongaonkar
We present a physical model of non-ohmic shunt current in a-Si:H p-i-n solar cells, and validate it with detailed measurements. This model is based on space-charge-limited (SCL) transport through localized p-i-p shunt paths, which can arise from contact metal incorporation in a-Si:H layer. This model explains both the electrical characteristics and the metastable switching behavior of the shunts within an integrated framework. We first verify the SCL model using simulations and statistically robust measurements, and then use this picture to analyze our systematic observations of non-volatile switching in these shunts. Our work not only resolves broad experimental observations on shunt …
Identification, Characterization, And Implications Of Shadow Degradation In Thin Film Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
Identification, Characterization, And Implications Of Shadow Degradation In Thin Film Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
Sourabh Dongaonkar
We describe a comprehensive study of intrinsicreliability issue arising from partial shadowing of photovoltaicpanels (e.g., a leaf fallen on it, a nearby tree casting a shadow,etc.). This can cause the shaded cells to be reverse biased, causingdark current degradation. In this paper, (1) we calculate thestatistical distribution of reverse bias stress arising from variousshading configurations, (2) identify the components of darkcurrent, and provide a scheme to isolate them, (3) characterizethe effect of reverse stress on the dark current of a-Si:H p-i-ncells, and (4) finally, combine these features of degradationprocess with shadowing statistics, to project ‘shadow-degradation’ (SD) over the operating lifetime …
Degradation Uniformity Of Rf-Power Gaas Phemts Under Electrical Stress, Anita Villanueva, Jesus Del Alamo, Takayuki Hisaka, Kazuo Hayashi, Mark Somerville
Degradation Uniformity Of Rf-Power Gaas Phemts Under Electrical Stress, Anita Villanueva, Jesus Del Alamo, Takayuki Hisaka, Kazuo Hayashi, Mark Somerville
Mark Somerville
We have studied the electrical degradation of RF-power PHEMTs by means of in situ 2-D light-emission measurements. Electroluminescence originates in the recombination of holes that have been generated by impact ionization. The local light intensity, thus, maps the electric-field distribution at the drain side of the device. This allows us to probe the uniformity of electrical degradation due to electric-field-driven mechanisms. We find that electrical degradation proceeds in a highly nonuniform manner across the width of the device. In an initial phase, degradation takes place preferentially toward the center of the gate finger. In advanced stages of degradation, the edges …
Key Performance Indicators Of A Transmission System, Omar H. Abdalla, Masoud Awlad-Thani, Mohamed Al-Wardi, Khalfan Al-Qaidi, Saqar Al-Farsi, Ibrahim Al-Balushi, Saeed Al-Mahdhoori
Key Performance Indicators Of A Transmission System, Omar H. Abdalla, Masoud Awlad-Thani, Mohamed Al-Wardi, Khalfan Al-Qaidi, Saqar Al-Farsi, Ibrahim Al-Balushi, Saeed Al-Mahdhoori
Omar H. Abdalla
The paper concerns with formulae and calculations of a selected group of Key Performance Indicators (KPIs) for the main electricity transmission system in Oman. These include the following service quality, reliability, security, and financial indicators [1]: &#; System Average Interruption Frequency Index (SAIFI) &#; System Average Interruption Duration Index (SAID) &#; Customer Average Interruption Duration Index (CAIDI) &#; Average Interruption Time (AIT) &#; Overhead Lines Maintenance Cost Index (OHLMCI) &#; Substation Maintenance Cost Index (SSMCI) Results of the main transmission grid in Oman, over the last 3 years, are presented. The results are useful in indicating trends of the KPIs …
Impact Of Interconnection Photovoltaic/Wind System With Utility On Their Reliability Using A Fuzzy Scheme, Dr. Adel A. Elbaset
Impact Of Interconnection Photovoltaic/Wind System With Utility On Their Reliability Using A Fuzzy Scheme, Dr. Adel A. Elbaset
Dr. Adel A. Elbaset
Reliability analysis has been considered as an important step in any system design process. a reliable electrical power system means that the system which having sufficient power to feed the load demand during a certain period or in other word, having small Loss of Load Probability (LOLP). LOLP is defined as an expected fraction of load not met by its needed power from electrical power system during its lifetime. Photovoltaic (PV) / Wind Energy System (WES) hybrid electric power system (PV/WES HEPS) differs considerably from the utility grid (UG) in their performance and operating characteristics. With the interconnection of PV/WES …