-
Transient Stability Analysis of the Nigeria 330-kV Transmission Network
Ignatius Kema Okakwu,
Emmanuel Apoyi Ogujor
Issue:
Volume 6, Issue 6, November 2017
Pages:
79-87
Received:
7 September 2017
Accepted:
26 September 2017
Published:
23 October 2017
Abstract: Assessment of the dynamic response of generators, within a power system, when subjected to various disturbances, has been a major challenge to power system researchers and engineers for the past decades. This paper investigates the dynamic response of the generators in the Nigeria 330-kV grid network when a balanced 3-phase fault is applied with the aim of determining the Critical Clearing Time (CCT) of the transmission network. The generalized swing equations for a multi-machine power system is presented. MATLAB software is employed as the tool for the simulations. A real network of Nigeria 330-kV electric grid is used as a case study. The result obtained clearly show that there exist critical buses such as Benin, Onitsha and Jebba Transmission Station (TS) and critical transmission lines such as Benin-Olorunshogo Generating Station (GS) and Jebba TS-Shiroro GS within the network. The results also reveal that the system losses synchronism when a balanced 3-phase fault is applied to these identified critical buses and lines. The results further indicate that the Nigeria 330-kV transmission network is on a red-alert, which requires urgent control measures with the aim of enhancing the stability margin of the network to avoid system collapse.
Abstract: Assessment of the dynamic response of generators, within a power system, when subjected to various disturbances, has been a major challenge to power system researchers and engineers for the past decades. This paper investigates the dynamic response of the generators in the Nigeria 330-kV grid network when a balanced 3-phase fault is applied with th...
Show More
-
Operating Cost for Optimal Performance of 100MW Gas Turbine Unit of Ughelli Power Plant
Ugwuoke Philip Emeka,
Obodeh Otunuya
Issue:
Volume 6, Issue 6, November 2017
Pages:
88-93
Received:
11 July 2017
Accepted:
7 August 2017
Published:
15 November 2017
Abstract: The operating cost for optimal performance of 100MW Delta IV gas turbine unit of Ughelli power plant was determined using optimum operating parameters and exergoeconomics. The optimizatioon tool is an evolutionary algorithm known as Genetic Algorithm (GA). The computer application used in this work is written in Matlab (Version 2011b) programming language. Eight optimal operating parameters of the plant were involved; compressor inlet temperature (T1), compressor pressure ratio (rp), compressor isentropic efficiency (ηic), turbine isentropic efficiency (ηit), turbine exhaust temperature (T4), air mass flow rate (ma), fuel mass flow rate (mf) and fuel supply temperature (Tf). Eight decision variables were optimally adjusted by the Genetic Algorithm (GA) to minimize the objective function. An objective function representing the total operating cost of the plant was defined in terms of N per hour as sum of operating cost (relating to the fuel consumption), rate of capital cost (relating to capital investment and maintenance expenses), and rate of exergy destruction cost. The optimal values of the decision variables (constraints) were obtained by minimizing the objective function. The GA optimal results obtained were ma= 530kg/s, mf= 7.00g/s. The GA operating cost and the component GA optimum results for exergy destruction cost rate and capital investment cost rate required to sustain optimum performance were obtained. The operating cost (Ċf), cost of exergy destruction rate (ĊD) and capital investment cost rate (ZK) for the compressor, combustion chamber and turbine are: (Ċf) = N244.72 per hour giving a variation of -0.57%, ĊDc = N87,728.32 per hour giving a variation of +13.59%, (ŻC) = N936,016.00 per hour giving a variation of -37.6% , (ĊDCC) = N470,288 per hour, a variation of -88.73%, ŻCC = N93,160.8 per hour, a variation of +305.6%, ĊDt = N144,278.4 per hour, a variation of -84.31%, Żt = N1,428,252.8 per hour a variation of +160.1%. These variations were in relation to base results.
Abstract: The operating cost for optimal performance of 100MW Delta IV gas turbine unit of Ughelli power plant was determined using optimum operating parameters and exergoeconomics. The optimizatioon tool is an evolutionary algorithm known as Genetic Algorithm (GA). The computer application used in this work is written in Matlab (Version 2011b) programming l...
Show More
-
Effects of Toshka Pumping Station Operations on Power Quality and Stability of Electrical Grid
Khaled Mohamed Kotb Fetyan
Issue:
Volume 6, Issue 6, November 2017
Pages:
94-112
Received:
13 August 2017
Accepted:
29 August 2017
Published:
21 November 2017
Abstract: Toshka is a large water pumping stations in Egypt. This station contains 21 units (18+3 Extentions) each 12MW. At a full capacity the full power consumptions can reach 200MW. The electrical feeding system for the stations contains; transformer, substations and Overhead transmission line (its long 300km), so the operations of the stations causes some problem for the electrical grid due to large value of power consumptions. In this paper, some problems were studied during the operations of the station. Effect of starting time on the station running and current consuming were studied. Also the effect of water level variations on the suctions side in Nasser Lake, speed changing, and power quality of the grid on the power consumptions. It was focused on the voltage and current variations, and the flicker occurred during the station operation. Finally the effects of number of harmonic filters used depending on the power rating of the unit, and effective short circuit ratio (ESCR) values on the stability of the electrical grid during the full load operations. The analyses of the results are obtained from actual measurement on the stations using modern power quality analyzers during different cases of operation are explained. This study is more useful for studying the problem occurred on the electrical grid during running of Toshka Stations, as it’s a large station in Egypt and has special design, at different cases and conditions of operation.
Abstract: Toshka is a large water pumping stations in Egypt. This station contains 21 units (18+3 Extentions) each 12MW. At a full capacity the full power consumptions can reach 200MW. The electrical feeding system for the stations contains; transformer, substations and Overhead transmission line (its long 300km), so the operations of the stations causes som...
Show More
-
Analysis of Correlation Among Partial Discharges, Ozone Emission, and Ultraviolet Radiation in High Voltage Motor Stator Windings
Tae-sik Kong,
Hee-dong Kim,
Soo-hoh Lee,
Jin Lee
Issue:
Volume 6, Issue 6, November 2017
Pages:
113-118
Received:
21 August 2017
Accepted:
5 September 2017
Published:
13 March 2018
Abstract: In this research, a normal winding and simulated defective winding were created to examine the correlation between partial discharges, ozone concentration, and ultraviolet radiation in high-voltage motor stator windings. In the simulated defective winding, the semiconductor layer was removed so that discharges could occur easily between the winding surface and the iron core. A high voltage was applied to both normal and defective windings to measure the partial discharge magnitude, ozone concentration, and ultraviolet radiation. Subsequently, the results were compared and analyzed. The electrical partial discharge magnitude, ozone emission, and ultraviolet radiation measurement methods and properties were explained, and all test results and correlations were analyzed.
Abstract: In this research, a normal winding and simulated defective winding were created to examine the correlation between partial discharges, ozone concentration, and ultraviolet radiation in high-voltage motor stator windings. In the simulated defective winding, the semiconductor layer was removed so that discharges could occur easily between the winding...
Show More
