Open Access Review Article

Control Techniques and Power Factor Correction Methods: A Review

Ganiyu Adedayo Ajenikoko, Oluwatomi Adigun, Amend Olayinka Rafiu

Journal of Engineering Research and Reports, Page 1-13
DOI: 10.9734/jerr/2018/v2i19883

The ratio of real power flowing into the load to the apparent power in a circuit is referred to as the power factor (PF). It has no unit as its values lie between 0 and 1. Power factor correction (PFC) leads to a reduction in apparent power drawn from the ac source which in turn saves energy and minimizes the transmission losses. This paper reviews various methods used for PFC as well as the various control measures for power factor. The correction methods include distributed PFC, group PFC, centralized PFC and combined PFC. Distributed PFC is applicable to large electrical equipment with constant load and power with long connection times. Combined PFC is the hybrid between a distributed and a centralized correction method. Peak current control technique makes use of constant switching frequency even though, the presence of sub-harmonic oscillations at a duty cycle greater than 50% is a disadvantage. The presence of constant switching frequency and better input current waveforms are some of the applications of average current control. In the discontinuous current pulse width modulation (PWM) control, the internal current loop is completely eliminated so that the switch is at a constant frequency. In nonlinear carrier controllers, the duty ratio is determined by comparing a signal derived from the main switch current with a periodic nonlinear carrier waveform. Therefore, combined PFC and nonlinear carrier controllers are more accurate PFC methods for the power plant because they employ a high power factor boost converter with low total harmonic distortion for installations of large equipment with a constant load. This research paper forms a basis for power system planning as it assists in recommending the appropriate and adequate technique(s) for correcting and controlling the pf of the factory.

Open Access Original Research Article

Design and Construction of 1 KVA Power Inverter System

A. E. Abioye, M. O. Ogbuatu, M. O. Oluwe, B. O. Egonwa, K. Ekiokeme

Journal of Engineering Research and Reports, Page 1-14
DOI: 10.9734/jerr/2018/v2i19890

The inverter system is a device that converts the Direct Current (DC) from a battery to an Alternating Current (AC) which can be used for appliances. It does not only convert the current but also steps the voltage of the battery up to the required value. The inverter system does not require fuel to make it function, that makes it cheap. 

The circuit has seven (7) embedded circuits in it; namely the oscillator circuit, which comprises the 4047 Oscillator Integrated Circuit (IC), It converts the DC current signal to AC signal at the same frequency.

The current modification circuit, this comprises the switching transistors and the cascaded MOSFETs, which modifies the current to the desired input to the step up transformer which steps it up to the required voltage and current. The battery low circuit indicates when the inverter battery is low, while the battery full circuit indicates when the inverter battery is full. The change over circuit changes the source from AC main to battery automatically. The rectifying circuit charges the battery and lastly the inverter on circuit: this indicates when the inverter is on.

The inverter system also has the battery full indicator, which helps to safe – guard the life of the battery while charging and it automatically switches of charging mode once the battery is full. The inverter system has timer for delaying the incoming current surge to protect the inverter from the large surge current and increase the working life of the inverter. The inverter was tested and the result obtained showed that it was able to bear the load up to 870 VA.

Open Access Original Research Article

Development of Software for Life Cycle Cost Analysis of Solar Photovoltaic (PV) and Diesel Generator Systems in Nigeria

Charles Chukwuma Mbah, Ogbonna Ukachukwu Oparaku, Emmanuel Chibuikem Nnadozie

Journal of Engineering Research and Reports, Page 1-9
DOI: 10.9734/jerr/2018/v2i19896

The human and economic development of any nation is largely tied to the availability of energy, hence the need for an adequate supply of electricity by reliable energy systems. Nigeria’s economic growth is undermined by the epileptic nature of its electricity supply system. Consequently, the populace is forced to turn to alternative sources of power. However, this presents another problem - conflict of choice between available options for power generation. There is, therefore, the need to assist electricity consumers in Nigeria make better and cost-effective choices in this regard. In this paper, a software computer program is developed to determine/compare life cycle cost (LCC) of solar photovoltaic (PV) and diesel generator systems as preferences for electricity generation in Nigeria. The software is developed through an approach involving load determination, energy resources determination, system sizing and a typical residential building. The key methodology adopted is evolutionary prototyping which focuses on vertical dimension approach. Typical load description of a household located in Amawbia Awka of Anambra state in Nigeria was used to test the efficiency of the source code. The initial cost and life cycle cost for the two systems over a period of 30 years was ascertained. The test results showed the solar PV system to be a more cost-effective solution than the diesel generator based on total life cycle costs. The study recommends among others, the need to increase awareness of the long-term benefits of solar energy systems as an alternative source of electricity in Nigeria.

Open Access Original Research Article

Selection and Optimization of Most Suitable Path Loss Prediction Model for Suburban City in Nigeria Using Spline Interpolation

A. Danladi, N. W. Silikwa, K. G. Gaya, A. H. Augustine

Journal of Engineering Research and Reports, Page 1-8
DOI: 10.9734/jerr/2018/v2i19900

Path loss is an attenuation of Global System for Mobile Communication (GSM) signal between Base Transceiver Station (BTS) and Mobile Station (MS). Path loss helps network engineers in planning, designing and implementing telecommunication networks. This work examines the applicability of Hata, COST 231, ECC – 33, Ericsson and SUI models in a medium city (Mubi) in Adamawa State, Nigeria. Root mean square error (RMSE) between the measured and the predicted losses (output of the models) is obtained as 7.632dB, 14.736dB, 10.593dB, 0.639dB and 23.491dB respectively. Ericsson model is found to have the least RMSE. Therefore, it is selected as the best fit model and modified. Furthermore, the modified model is optimized to recover missing or to eliminate unwanted information in the radio path using spline interpolation. The optimized model can be employed for the deployment of network resources in suburban areas of Nigeria, especially in Mubi town in Adamawa State, in order to significantly enhance GSM signal QoS. It is recommended that fuzzy logic and spline interpolation techniques may be integrated and employed to further minimize the error obtained in this work.

Open Access Original Research Article

Reading and Interpreting Machine Printed Text in Camera-Captured Document Images

V. J. Rehna, Abid Siddique, Sreenivas Naik

Journal of Engineering Research and Reports, Page 1-10
DOI: 10.9734/jerr/2018/v2i19904

Aims: To introduce a cost-effective tool for reading and interpreting machine printed text in document images and save as computer-processable codes.

Study Design:  In this work, emphasize is given on extracting uppercase & lowercase letters and numerals from document images by the technique of segmentation and feature extraction using MATLAB Image Processing toolbox.

Place and Duration of Study: Department of Engineering, Ibri College of Technology, between September 2017 and May 2018.

Methodology: Necessary information about existing algorithms on character recognition is collected by review of relevant literature available in journals, books, manuals and related documents. Suitable architecture and novel algorithm for a simple, low cost, low complexity, highly accurate system is developed as per the specifications and reviewed literature. Functionality of the design is verified using simulation software MATLAB.

Results: The proposed method can extract characters from document image (which may be scanned or camera captured) of any font size, colour, space and can be rewritten in an editable window like Notepad, WordPad where the characters can even be edited; thus, improving accuracy and hence, saves time.

Conclusion: This algorithm gives promising results that have been obtained on a number of images in which almost all characters are retrieved. It also gives 90 percent accuracy for all printed characters.