A comparative study of Quasi-FEA technique on iron losses prediction for permanent magnet synchronous machines

The paper presents an advanced quasi-FEA technique on the iron losses prediction using Bertotti’s iron loss separation models, in which a curve fitting is taken into account for coefficients calculation of each model. Moreover, the skin effect and saturation consideration are applied in order to check the accuracy through the relative error distribution in the frequency domain of each model from low up to high frequencies 50 to 700 (Hz). Additionally, this comparative study presents a torquespeed-flux density computation that is discussed and presented. The iron loss characteristics of a radial flux permanent magnet synchronous machine (PMSM) with closed-slots and outer rotor topology are also discussed. The quasi-finite-element (FE) analysis was performed using a 2-D and 3-D FEA, where the employed quasi-2-D FEA is proposed and compared with 3-D FEA, and along with experimental verifications. Finally, all the iron-loss models under realistic and non-ideal magnetization conditions are verified experimentally on a surface-mounted PMSG for wind generation application.Peer ReviewedPostprint (published version

Smart integration of a DC microgrid: Enhancing the power quality management of the neighborhood low-voltage distribution network

The fast development of the residential sector regarding the additional integration of renewable distributed energy sources and the modern expansion usage of essential DC electrical equipment may cause severe power quality problems. For example, the integration of rooftop photovoltaic (PV) may cause unbalance, and voltage fluctuation, which can add constraints for further PV integrations to the network, and the deployment of DC native loads with their nonlinear behavior adds harmonics to the network. This paper demonstrates the smart integration of a DC microgrid to the neighborhood low-voltage distribution network (NLVDN). The DC microgrid is connected to the NLVDN through a three-phase voltage source inverter (VSI), in which the VSI works as a distribution static compensator (DSTATCOM). Unlike previous STATCOM work in the literature, the proposed controller of the VSI of the DC smart building allows for many functions: (a) it enables bidirectional active/reactive power flow between the DC building and the AC grid at point of common coupling (PCC); (b) it compensates for the legacy unbalance in the distribution network, providing harmonics elimination and power factor correction capability at PCC; and (c) it provides voltage support at PCC. The proposed controller was validated by Matlab/Simulink and by experimental implementation at the lab

Wide area condition monitoring of power electric drives in wind power generation system using radiated electromagnetic fields

Electric components in numerous applications (particularly wind generation) are not straightforwardly accessible for monitoring. Therefore, the monitoring and protection through voltage/current measurement may not be dependable since the current value passes numerous segments to reach the observing element. Accordingly, finding an unusual phenomenon of a specific element is difficult. To resolve this issue, using transmitted electromagnetic field of an element for wide area condition monitoring is proposed. It is planned to diagnose and locate short-circuit in induction generator drive such as interturn, intercoil and terminal-to-turn failures. The frequency characteristics of the propagated field is then utilized for finding the short-circuit. The theoretical foundation that relate the behavior of each elements to their frequency response is analyzed and used. To utilize the derived technique for different practical circumstances, two distinctive methods are used for locating the short-circuit. As the experimental test of major fault cases could destruct the winding, the full three-dimensional finite element analysis is used in these cases and some are verified experimentally through the wide area communication. Identifying the areas of partial faults Prevents the whole winding failure prior to a massive destruction, which is costly especially for cases in inaccessible situations such as offshore wind towers

Optimal power routing scheme between and within interlinking converters in unbalanced hybrid AC–DC microgrids

An optimal power routing (OPR) scheme between and within interlinking converters (ICs) in unbalanced hybrid AC–DC microgrids to minimise the power imbalance factor at the point of common coupling, active power losses, and voltage deviation indices for microgrids in grid-connected operating mode is proposed in this study. These goals are achieved through a multi-objective optimisation model by optimal distributing of mobile loads between available charging stations and at the same time, OPR within three phases of three-phase four-lag AC/DC converters. Numerical results obtained from implementing the proposed method on the modified IEEE 13-bus system, as an unbalanced hybrid microgrid, and IEEE 34-bus test system, as an unbalanced distribution system, demonstrate that proposed OPR algorithm is successful to satisfy the optimisation goals. For this purpose, four case studies are defined and studied to demonstrate the unique features of the proposed OPR comparing with other power routing schemes. In addition to simulation results, the OPR scheme between ICs is realistically implemented at Florida International University smart grid testbed to show the effect of the power routing on energy losses reduction

Sectional variable frequency and voltage regulation control strategy for energy saving in beam pumping motor systems

Despite the fact that the energy losses in the beam pumping motor systems (BPMS) utilized in oil fields represent a monumental challenge industrially, very few studies discussed the feasibility and applicability of a universal energy saving technology for such industry. This study proposes a sectional control strategy integrating variable frequency (VF) with voltage regulation (VR) based on the mechanical load characteristics of the BPMS. Main merits of the proposed strategy are as follows: 1) controlling horse-head acceleration through VF, and indirectly weakening the inertia torque of polished rod load, thereby reducing the power consumption during the up-stroke; and 2) based on monitoring load conditions in real time, auto-tracking VR is adopted to optimize the online efficiency of the system. The proposed strategy utilized the adaptive fuzzy logic control to alternate between VF and VR modes. The proposed energy saving strategy was applied to a CYJ10 BPMS driven via a 37-kW induction motor in simulation and experimental environments. Results revealed that the effectiveness of the proposed strategy to improve the load balance effects through better utilization of the counterbalance during the heavy-loading conditions in up-stroke. Furthermore, the energy consumption is reduced via the auto-tracking of VR under light-loading conditions during the down-stroke. Moreover, the energy saving ratio is more than 10% under different dynamic liquid levels and counter weights. The effectiveness of the proposed strategy is verified through comparing the calculated results with the measured data for a standard oil rig, and the generality is verified as well

Protective effect of camel milk as anti-diabetic supplement: biochemical, molecular and immunohistochemical study

Background: Diabetes is a serious disease affects human health. Diabetes in advanced stages is accompanied by general weakness and alteration in fats and carbohydrates metabolism. Recently there are some scientific trends about the usage of camel milk (CM) in the treatment of diabetes and its associated alterations. CM contains vital active particles with insulin like action that cure diabetes and its complications but how these effects occur, still unclear.Materials and Methods: Seventy-five adult male rats of the albino type divided into five equal groups. Group 1 served as a negative control (C). Group 2 was supplemented with camel milk (CM). Diabetes was induced in the remaining groups (3, 4 and 5). Group 3 served as positive diabetic control (D). Group 4 served as diabetic and administered metformin (D+MET). Group 5 served as diabetes and supplemented with camel milk (D+CM). Camel milk was supplemented for two consecutive months. Serum glucose, leptin, insulin, liver, kidney, antioxidants, MDA and lipid profiles were assayed. Tissues from liver and adipose tissues were examined using RT-PCR analysis for the changes in mRNA expression of genes of carbohydrates and lipid metabolism. Pancreas and liver were used for immunohistochemical examination using specific antibodies.Results: Camel milk supplementation ameliorated serum biochemical measurements that altered after diabetes induction. CM supplementation up-regulated mRNA expression of IRS-2, PK, and FASN genes, while down-regulated the expression of CPT-1 to control mRNA expression level. CM did not affect the expression of PEPCK gene. On the other hand, metformin failed to reduce the expression of CPT-1 compared to camel milk administered rats. Immunohistochemical findings revealed that CM administration restored the immunostaining reactivity of insulin and GLUT-4 in the pancreas of diabetic rats.Conclusion: CM administration is of medical importance and helps physicians in the treatment of diabetes mellitus.Keywords: Camel milk, Diabetes, Gene expression, Immunohistochemistr

Effects of Noise on Rabbit’s Blood

Experiments are described in which domestic rabbits were deliberately subjected to a daily 3-4 hours noise regime (65 dB) for 18, 28, 40 and 50 days, to determine its effects on the blood. Noise exposure to rabbits caused a general increase in its biochemical parameters such as urea, uric acid, creatinine, cholesterol, and triglycerides, while glucose level decreased significantly. Our results indicate a general decrease of total protein, albumin and globulin levels. The results indicated that noise exposure at split dose could be harmful. It found that recovery period were able to alleviate some of those harmful changes

Anti-Müllerian hormone and response to ovulation induction with clomiphene citrate in women with polycystic ovary syndrome

Background: Anti-Müllerian hormone (AMH) is suggested as an important marker for women with polycystic ovary disease (PCOS). Several studies have found serum level of AMH correlate well to ovarian response to ovulation induction in women with PCOS. This study was conducted to assess the relationship between AMH in women with PCOS and response to ovulation induction with clomiphene citrate.Methods: Prospective observational cohort study conducted at Ain-Shams university maternity hospital from February 2013 to February 2014. 100 women with PCOS were recruited from the infertility outpatient clinic. Serum AMH levels were measured by enzyme linked immunosorbent assay in the early follicular phase (days 3-5). Ovulation induction by clomiphene citrate was started on day 5 as 50 mg daily tablet for 5 days. Ovulation was documented by transvaginal ultrasonography and women who failed to ovulate till day 35 were considered anovulatory.Results: 72 women ovulated within 12 to 33 days of the menstrual cycle, while 28 had undetectable ovulation till day 35. The median serum AMH level was significantly higher in women with failed ovulation [4.05 ng/mL (3.7 - 4.4)] than in ovulating women [2.7 ng/mL (1.9 - 3.1)] (p<0.001). Receiver-operating characteristic (ROC) curve analysis found the best cutoff value of AMH for prediction of successful ovulation ≤3.6 ng/mL (sensitivity = 97.2%, specificity = 82.1%).Conclusions: Anti-Müllerian hormone is a very useful predictor of poor responders to clomiphene citrate among women with polycystic ovary disease