Papers by teshome goa tella
Innovative Systems Design and Engineering, 2015
In modern electric power distribution systems especially at industrial distribution, there is a s... more In modern electric power distribution systems especially at industrial distribution, there is a sharp rise in the use of non-linear loads due to high growth in industrial loads. These non-linear loads generally have solid state control of electric power and draw a non-sinusoidal unbalanced current from AC mains which resulting in harmonics injection, reactive power burden, excessive neutral currents and unbalanced loading of AC mains. In this project the industries in Mekelle city named as MAA-Garment power quality (harmonic) problem was investigated and remedies has been givenby designing filters based onitspower quality problems. So far, a number of attempts have been made on the analysis, design and development of equipment generally named as active power filter (APF) to provide a dynamic and adjustable solution to eliminate harmonics and reactive power burden on the AC mains. The work entitled here concentrated on the new control scheme of series inductive filters. The dominating sources of distortion, at MAA-Garment industry are motors, converters, power factor correction capacitor& other electronic devices plus machines. The presence of that non-linear equipment in factory yields an increasing of harmonic current on Management distribution system which leads to degradation of system performance of machines. Therefore, the mitigation technique to overcome this problem was accomplished by designing series inductive filter at branches of non-linear loads and the total harmonic order was reduced from 7 th to less than 5 th order at the respective nodes. .
Voltage Stability Assessment on Ethiopian 230 KV Transmission Network Using Modified Voltage Stability Indices
2018 IEEE PES/IAS PowerAfrica, 2018
This paper presents a method for performing voltage stability analysis and ranking of network bus... more This paper presents a method for performing voltage stability analysis and ranking of network buses using user-modified voltage stability indices (MVSI). In the study, Ethiopian 230 KV power system is modeled and Newton Raphson power flow analysis is carried out using power system stability analysis toolbox (PSAT). In this analysis, base load data is used to determine the steady state power flow solution. To account for loading effects on bus voltage stability, the load reactive power is increased to its maximum stability limit and modified voltage stability indices determined. Buses are ranked in descending order based on their load voltage stability severity using modified voltage stability indices. The results show that the modified voltage stability index techniques is effective for ranking of load buses in meshed power networks compared to conventional methods.
Journal of Electrical and Computer Engineering, Aug 23, 2022
In this paper, static voltage stability assessments and their improvement using analytical and op... more In this paper, static voltage stability assessments and their improvement using analytical and optimization techniques with di erent loading scenarios are described. In this study, the 400 kV, 230 kV, and 132 kV Ethiopian electric power networks are modeled using Power System Analysis Toolbox (PSAT), and the load ow analysis is carried out using MATLAB source code. en, di erent voltage stability indices, such as the user-de ned advanced voltage stability index (AVSI), modi ed voltage stability index (MVSI), and fast voltage stability index (FVSI), are used to identify the voltage unstable buses. Besides this, particle swarm optimization (PSO) is also used to nd the optimal size and placement of the Static Synchronous Compensator (STATCOM) for the most severe buses identi ed by voltage stability indices. e result presents three special arguments: whether the most severe buses that are ranked at the top based on the voltage stability indices are optimal buses for compensation placement or not, the voltage stability improvement, and power loss reduction with the introduction of STATCOM. Accordingly, it is observed that the weakest bus that is identi ed through the stability indices may not be the optimal placement of the compensation device. It is also indicated that, with the introduction of STATCOM to the optimal selected bus, the network power loss is reduced from 46.65 MW to 33.32 MW and its voltage magnitude in all buses is also improved. All bus voltages are within the IEEE standard acceptable limit.
Recently the utility is facing severe voltage stability problems so that to satisfy end users exp... more Recently the utility is facing severe voltage stability problems so that to satisfy end users exponential growth of energy demands. As a solution, considering high operational cost of constructing new power generation, transmission and distribution system the utility is connecting more loads on existing load buses up to their thermal limits. But in power system increasing inductive load brings voltage stability problem due to an armature reaction. Thus, if we connect an additional inductive load, the armature reaction is subtractive to the main field, resulting in voltages fall-down and hence yields further voltage collapses. In addition, since under heavy load the line absorbs more reactive power than it generates, leads to transmission line stresses and its fall down when it exceeds maximum thermal limits. Therefore, this article targets finding voltage stability margins of load buses and ranking them based on their severity indexes for reactive load power changing using user modi...
Excessive reactive power loading results in bus voltage instability and outage of power transmiss... more Excessive reactive power loading results in bus voltage instability and outage of power transmission lines, which leads to instability of the entire power network. For stable operation, finding the stability margin of buses and lines by identifying and ranking unstable lines under contingency is needed. The aim of contingency ranking is to recommend the stability improvement mechanisms for a secure and stable power network operation. This paper introduces a new line stability index that is used to rank lines to identify unstable lines based on the severity of load contingency. In addition, another new technique called Aggregated-Variance Stability Index (AVSI) in combination with adaptive neuro-fuzzy inference system is used to rank the lines based on the severity of line outage contingency due to excessive reactive power loading. Further, to account for the effect of inductive load on bus voltage and power transmission line stability, only load reactive power is increased up to its...
Voltage Stability Assessment on Ethiopian 230 KV Transmission Network Using Modified Voltage Stability Indices
2018 IEEE PES/IAS PowerAfrica
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Papers by teshome goa tella