Science & Technology Development Journal - Engineering and Technology

Optimal location and impacts of 1 MWP solar pv plants on distribution network protection

2021-08-26T08:52:07+00:00

Nowadays, the penetration of the distributed energy resources into the power distribution network is increasing, especially the 1 MWp solar PV plants since they have been enjoying the Feed-in tariff scheme. In order to reduce the losses of the distribution power network efficiently, this paper uses the Symbiotic Organism Search (SOS) algorithm to determine the optimal location for these solar power sources. However, when these distributed power sources are connected to the distribution network, they can cause to lose the selective coordination between reclosers and fuses - the main protection devices of the distribution network. The prominent feature of this report is to be based on the availability of reclosers, fuses, and with consideration of the Khc coefficient (which is affected by the time and number of reclose attempts). Hence, a simple but efficient solution is proposed to ensure selective recloser – fuse coordination. The mentioned SOS algorithm and the solution are to be applied to the 473TH 22 kV distribution network in Tay Ninh province. The simulation results using Matlab and Etap indicate that the SOS algorithm along with the proposed solution are beneficial to planning and locating distributed power sources, and simultaneously help to overcome the non-selective recloser – fuse coordination.

Shaping the tooth profile of elliptical gear with the involute ellipse curve

2021-08-30T00:14:22+00:00

Non-circular gears (NCGs) with the advantage of compactness and simple mechanical structure in creating transmitters with variable gear ratios in the industry, so this is a topic that is being studied by many scientists. However, up to now the research usually focuses on NCGs with tooth profile that is an involute circle called involute tooth profile, while other curves have not been applied in the design of the non-circular gears. In this paper, the author proposes to apply the involute ellipse curve in shaping the tooth profile of the pair of elliptical gears with a rack cutter. A rack cutter with tooth profiles is trapezoidal weight is determined from the involute ellipse curve selected as the NCGs teeth. In order not to undercut and tip sharpening when shaping the gear, two algorithms for correcting the base ellipse according to the even distribution of teeth on the gear and undercutting avoidance condition are performed. A numerical computational software module is written according to the theory and the algorithm is implemented to explore the different cases in the design process. The results of this study show that the teeth are evenly distributed over the entire circumference of the ring elliptical gear, overcoming the phenomenon of uneven teeth in geometry and size when using the involute of a circle as other studies have shown. Also, with the tooth profile that is involute ellipse curve, the pressure angle is increased to improve efficiency the transmission capacity of a pair of gears. Therefore, this is the advantage of the new profile in creating variable automatic transmission for different script applications in industries such as the automotive industry or modern medical equipment.

Research on application of industrial robots in automated fueling systems for small individual cars

2021-09-04T02:32:10+00:00

An automated fueling system for small individual vehicles, such as 4- and 7-passenger cars, is necessary in the modern life. Currently in the car market, in terms of the characteristics of the equipped fuel tanks, it can be divided into two main groups, including the vehicles using the traditional fuel tanks and the vehicles using the cap-less fuel tanks. For the vehicles using the traditional fuel tanks, the vehicle drivers need 4 steps to pump the gasoline. They are opening the outer lid of the body, opening the screw cap on the fuel tank, putting the pump nozzle into the fuel tank and making the fuel pump. For the vehicles using the cap-less fuel tank design, the manufacturers replace the traditional screw cap with the self-opening (close) lid mechanism when there is (without) the pump nozzle. So when operating the gasoline pump, there is no step to open the screw cap on the fuel tank. This new design was pioneered by American car manufacturers such as Ford and General Motor. This paper proposes a solution for the automatic fueling for the vehicles that have the fuel tank without the screw cap. The system is built based on an industrial robot that do the task replacing for the station officer. Firstly, a special tool is designed to help the robot to operate during the automatic fueling. Next, an image processing algorithm is applied to recognize the position of the fuel tank of the vehicles. After that, an automatic fueling algorithm is proposed so that the system can do fueling automatically. The proposed solution is verified by the experiments on the real model. The experimental results show that the proposed system can be used to position the nozzle into the fuel tank with the acceptable error

Research of Applying forecasting theory to establish the optimal load transfer strategy for maintenance at 110kV substation

2021-09-07T23:22:20+00:00

Regarding electric power systems, Short-Term load forecasting plays a pivotal role in the planning and synchronous operation of an electric grid. In recent years, because of the computer industry developing at an ever-accelerating rate, plenty of sophisticated load forecasting models have been better utilized, thereby becoming more and more widely used. However, in VietNam, there is no practical use of these models, and load forecasting is still mainly based on engineers’ personal experiences. Due to the fact that experiences are not absolutely precise, applying conventional load forecasting techniques easily results in many severe consequences. Therefore, in this article, the necessity, as well as benefits of using load forecasting models for the VietNam power grid, will be clearly and thoroughly demonstrated. This paper, additionally, provides a suggested optimal load transfer strategies for 110 kV substations when these substations are under maintenance, avoiding overload for transformers and nearby feeders. Through specific examples and statistics data, the efficiency of methods suggested in this article has been proved.

Calibrating water distribution network models and identifying interference areas between water sources on the network in the North of Ho Chi Minh City

2021-09-10T22:06:31+00:00

The realistic simulation model of a water distribution network has been widely applied in water resource management, from optimization design to operation management. However, the calibration of the model simulation to adapt with reality is still a challenging task, because within the water distribution network, there are numerous unknown variables, such as: variant consumptions, pipeline characteristics, losses and uncontrollable or non-revenue water, especially flows at potential leak points. This study presents the simulation and calibration of the hydraulic model of the water distribution network in the Northern area of Ho Chi Minh City, including Go Vap District and a part of District 12. The network currently supplies water for more than 140.000 water meters and the water flow into and out of the network in real time is controlled in the study area. The results of the calibration of the water distribution network model are assessed to be consistent with the actual operation in terms of flow and water pressure changes during the day at the observation points by performance metrics. On that basis, the study continues to apply the calibrated model to analyze the water source tracing to determine the interference areas between two water sources in the study area from two water treatment plants.

Design of low cost-remote eye tracker using Pupil Center-Corneal Reflection technique

2021-09-10T22:35:18+00:00

The eye tracker is used in many fields such as education, marketing, psychology, medicine, among others. However, commercial devices are costly, spanning from a few hundred to several thousand dollars. Therefore, an inexpensive-monocular-remote (IMR) eye tracker is developed for education and research, which implements the Pupil-Center-Corneal-Reflection technique. The IMR device consists of a low-cost camera with a near-IR pass filter that captures subject’s eye images, a moderate-cost computer that processes these images, as well as two near-IR light sources that create glints and illuminate the eye. The pupil detection algorithm is developed by combining the advantages of two recent algorithms, named BORE and PDIF, and gaze points are estimated from pupil-glints vectors via a fourth-order polynomial. An experimental evaluation is conducted concurrently on the research eye tracker IMR at the operating frequency of 30 Hz and the commercial-high-end-head-free device VT3 Mini at 60 Hz, in a challenge condition: subjects sit down near a window, and some of them wear glasses. Also, their heads are placed on a fixed chin rest, and the data is acquired when both devices successfully estimate gaze points. The experimental results in 11 sample data, obtained from 7 subjects, show that the overall ratio of the number of filtered/raw samples and raw/idea samples are 88.92% and 98.63% in order. Whereas the overall precision of the IMR eye tracker is nearly equal to that of the VT3 Mini device (0.57 degrees and 0.54 degrees, respectively), the overall accuracy of the proposed eye tracker is better than that of the commercial device (1.04 degrees and 1.34 degrees, respectively). Regarding eye safety, the radiant power and the burn-hazard-weighted radiance of the proposed device are much smaller than their limitations, according to IEC 62471. With these results, the IMR eye tracker is appropriate for education and needs to be improved in terms of data validation to satisfy the research purpose.

Study of glycerol-methanol and sorbitol-methanol mixed feed strategies for recombinant hPDGF-BB production in Pichia pastoris

2021-09-13T22:12:49+00:00

The recombinant human platelet-derived growth factor type BB (rhPDGF-BB) protein has been approved by FDA for diabetic foot ulcer treatment due to its function of stimulating cell proliferation and wound healing. In this study, the production of rhPDGF-BB from Pichia pastoris is studied in a 7.5 L fermentation using methanol as carbon source and inducer in induction phase. The specific growth rate of the recombinant strain reduced 1.833-fold and rhPDGF-BB productivity reduced 2.13-fold compared to at 0.5 L. To improve growth and protein expression of the strain in induction phase, the mixed feed strategy, in which glycerol or sorbitol was co-fed with methanol at three different molar ratios (1:1, 1:2 and 1:3) was conducted. Using the mixture of glycerol and methanol at the molar ratio 1:2 and the mixture of sorbitol and methanol at the molar ratio 1:3 increased the productivity of rhPDGF-BB protein 1.32-fold (280,48 mg/L) and 1.24-fold (264,15 mg/L), respectively, higher than using only methanol in the induction phase of the fermentation process.