This research presents a method for reliability assessment considering the 23MVA, 230/15 kV
transformer through two 15 kV outgoing transmission lines at Debre Markos substation. It also goes further to
include 139 low voltage 15/0.4 kV distribution transformers. The total load connected to the 15 kV feeders are
varies between 0.33255 and 6.3185 MW. A composite system adequacy and security assessment is done using
Monte Carlo simulation. The basic data and the topology used in the analysis are based on the Institution of
Electrical and Electronics Engineers - Reliability Test System and distribution system for bus two of the IEEEReliability
Bus bar Test System. The reliability indices SAIDI, SAIFI, CAIDI, EENS, AENS, ASAI, ASUI, and
expected interruption costs are being assessed and considered. Distribution system reliability information was
obtained from actual data for systems operating in Ethiopia Electric Utility office and Debre Markos substation
recorded data and online SCADA system.
INTRODUCTION TO POWER SYSTEM STABILITY BY Kundur Power Systems SolutionsPower System Operation
Power System Stability denotes the ability of an electric power system, for a given initial operating condition, to regain a state of operating equilibrium after being subjected to a physical disturbance, with all system variables bounded so that the system integrity is preserved
Integrity of the system is preserved when practically the entire power system remains intact with no tripping of generators or loads, except for those disconnected by isolation of the faulted elements or intentionally tripped to preserve the continuity of operation of the rest of the system
Stability is a condition of equilibrium between opposing forces:
instability results when a disturbance leads to a sustained imbalance between the opposing forces
instability is a run-away or run-down situation
This is the third slide set in series of Introductory course on Power Quality for undergraduates. This deals with transient over-voltages, Ferro Resonance, Over Voltage Protection, Switching Transients, Shielding
Detailed presentation created on the topic of electrical power subject on the power system analysis. Shown about Ybus details, Ybus calculations, Power flow and design, Interconnected operation of power system etc.
Automatic generation control (AGC) is a system for adjusting the power output of multiple generators at different power plants, in response to changes in the load. Since a power grid requires that generation and load closely balance moment by moment, frequent adjustments to the output of generators are necessary. The balance can be judged by measuring the system frequency; if it is increasing, more power is being generated than used, which causes all the machines in the system to accelerate. If the system frequency is decreasing, more load is on the system than the instantaneous generation can provide, which causes all generators to slow down.
INTRODUCTION TO POWER SYSTEM STABILITY BY Kundur Power Systems SolutionsPower System Operation
Power System Stability denotes the ability of an electric power system, for a given initial operating condition, to regain a state of operating equilibrium after being subjected to a physical disturbance, with all system variables bounded so that the system integrity is preserved
Integrity of the system is preserved when practically the entire power system remains intact with no tripping of generators or loads, except for those disconnected by isolation of the faulted elements or intentionally tripped to preserve the continuity of operation of the rest of the system
Stability is a condition of equilibrium between opposing forces:
instability results when a disturbance leads to a sustained imbalance between the opposing forces
instability is a run-away or run-down situation
This is the third slide set in series of Introductory course on Power Quality for undergraduates. This deals with transient over-voltages, Ferro Resonance, Over Voltage Protection, Switching Transients, Shielding
Detailed presentation created on the topic of electrical power subject on the power system analysis. Shown about Ybus details, Ybus calculations, Power flow and design, Interconnected operation of power system etc.
Automatic generation control (AGC) is a system for adjusting the power output of multiple generators at different power plants, in response to changes in the load. Since a power grid requires that generation and load closely balance moment by moment, frequent adjustments to the output of generators are necessary. The balance can be judged by measuring the system frequency; if it is increasing, more power is being generated than used, which causes all the machines in the system to accelerate. If the system frequency is decreasing, more load is on the system than the instantaneous generation can provide, which causes all generators to slow down.
Infinite bus bar is one which keeps constant voltage and frequency although the load varies. Thus it may behave like a voltage source with zero internal impedance and infinite rotational inertia.
Physical Description
Mathematical Model
Park's "dqo" transportation
Steady-state Analysis
phasor representation in d-q coordinates
link with network equations
Definition of "rotor angle"
Representation of Synchronous Machines in Stability Studies
neglect of stator transients
magnetic saturation
Simplified Models
Synchronous Machine Parameters
Reactive Capability Limits
Consists of two sets of windings:
3 phase armature winding on the stator distributed with centres 120° apart in space
field winding on the rotor supplied by DC
Two basic rotor structures used:
salient or projecting pole structure for hydraulic units (low speed)
round rotor structure for thermal units (high speed)
Salient poles have concentrated field windings; usually also carry damper windings on the pole face.Round rotors have solid steel rotors with distributed windings
Nearly sinusoidal space distribution of flux wave shape obtained by:
distributing stator windings and field windings in many slots (round rotor);
shaping pole faces (salient pole)
Symmetrical Components
Symmetrical Component Analysis
Synthesis of Unsymmetrical Phases from Their Symmetrical Components
The Symmetrical Components of Unsymmetrical Phasors
Phase Shift of Symmetrical Components in or Transformer Banks
Power in Terms of Symmetrical Components
Unsymmetrical Faults
Unsymmetrical faults are the faults which leads unequal currents with unequal phase shifts in a three phase system.
The unsymmetrical fault occurs in a system due to presence of an open circuit or short circuit of transmission or distribution line. It can occur either by natural disturbances or by manual errors. The natural disturbances are heavy wind speed, ice loading on the lines, lightening strokes and other natural disasters.
The open circuit or short circuits of transmission or distribution lines will lead to unsymmetrical or symmetrical faults in the system. In case of tree branches falling on lines, a short circuit of transmission lines will occur.
These line faults are classified as,
1. Single line to ground faults (LG fault)
2. Double line fault (LL fault)
3. Double line to ground fault (LLG fault)
Single line to ground fault is the most frequently occurring fault (60 to 75% of occurrence). This fault will occur when any one line is in contact with the ground. Double line fault occurs when two lines are short circuited. This type of fault occurrence ranges from 5 to 15%. Double line to ground fault occurs when two lines are short circuited and is in contact with the ground. This type of fault occurrence ranges from 15 to 25% of occurrence.
Infinite bus bar is one which keeps constant voltage and frequency although the load varies. Thus it may behave like a voltage source with zero internal impedance and infinite rotational inertia.
Physical Description
Mathematical Model
Park's "dqo" transportation
Steady-state Analysis
phasor representation in d-q coordinates
link with network equations
Definition of "rotor angle"
Representation of Synchronous Machines in Stability Studies
neglect of stator transients
magnetic saturation
Simplified Models
Synchronous Machine Parameters
Reactive Capability Limits
Consists of two sets of windings:
3 phase armature winding on the stator distributed with centres 120° apart in space
field winding on the rotor supplied by DC
Two basic rotor structures used:
salient or projecting pole structure for hydraulic units (low speed)
round rotor structure for thermal units (high speed)
Salient poles have concentrated field windings; usually also carry damper windings on the pole face.Round rotors have solid steel rotors with distributed windings
Nearly sinusoidal space distribution of flux wave shape obtained by:
distributing stator windings and field windings in many slots (round rotor);
shaping pole faces (salient pole)
Symmetrical Components
Symmetrical Component Analysis
Synthesis of Unsymmetrical Phases from Their Symmetrical Components
The Symmetrical Components of Unsymmetrical Phasors
Phase Shift of Symmetrical Components in or Transformer Banks
Power in Terms of Symmetrical Components
Unsymmetrical Faults
Unsymmetrical faults are the faults which leads unequal currents with unequal phase shifts in a three phase system.
The unsymmetrical fault occurs in a system due to presence of an open circuit or short circuit of transmission or distribution line. It can occur either by natural disturbances or by manual errors. The natural disturbances are heavy wind speed, ice loading on the lines, lightening strokes and other natural disasters.
The open circuit or short circuits of transmission or distribution lines will lead to unsymmetrical or symmetrical faults in the system. In case of tree branches falling on lines, a short circuit of transmission lines will occur.
These line faults are classified as,
1. Single line to ground faults (LG fault)
2. Double line fault (LL fault)
3. Double line to ground fault (LLG fault)
Single line to ground fault is the most frequently occurring fault (60 to 75% of occurrence). This fault will occur when any one line is in contact with the ground. Double line fault occurs when two lines are short circuited. This type of fault occurrence ranges from 5 to 15%. Double line to ground fault occurs when two lines are short circuited and is in contact with the ground. This type of fault occurrence ranges from 15 to 25% of occurrence.
Power System Reliability Assessment in a Complex Restructured Power SystemIJECEIAES
The basic purpose of an electric power system is to supply its consumers with electric energy as parsimoniously as possible and with a sensible degree of continuity and quality. It is expected that the solicitation of power system reliability assessment in bulk power systems will continue to increase in the future especially in the newly deregulated power diligence. This paper presents the research conducted on the three areas of incorporating multi-state generating unit models, evaluating system performance indices and identifying transmission paucities in complex system adequacy assessment. The incentives for electricity market participants to endow in new generation and transmission facilities are highly influenced by the market risk in a complex restructured environment. This paper also presents a procedure to identify transmission deficiencies and remedial modification in the composite generation and transmission system and focused on the application of probabilistic techniques in composite system adequacy assessment
Optimal Placement and Sizing of Distributed Generation Units Using Co-Evoluti...Radita Apriana
Today, with the increase of distributed generation sources in power systems, it’s important to
optimal location of these sources. Determine the number, location, size and type of distributed generation
(DG) on Power Systems, causes the reducing losses and improving reliability of the system. In this paper
is used Co-evolutionary particle swarm optimization algorithm (CPSO) to determine the optimal values of
the listed parameters. Obtained results through simulations are done in MATLAB software is presented in
the form of figure and table in this paper. These tables and figures, show how to changes the system
losses and improving reliability by changing parameters such as location, size, number and type of DG.
Finally, the results of this method are compared with the results of the Genetic algorithm (GA) method, to
determine the performance of each of these methods.
Optimum allocation of distributed generation by load flow analysis method a c...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
On-line Power System Static Security Assessment in a Distributed Computing Fr...idescitation
The computation overhead is of major concern when
going for increased accuracy in online power system security
assessment (OPSSA). This paper proposes a scalable solution
technique based on distributed computing architecture to
mitigate the problem. A variant of the master/slave pattern is
used for deploying the cluster of workstations (COW), which
act as the computational engine for the OPSSA. Owing to the
inherent parallel structure in security analysis algorithm, to
exploit the potential of distributed computing, domain
decomposition is adopted instead of functional decomposition.
The security assessment is performed utilizing the developed
composite security index that can accurately differentiate the
secure and non-secure cases and has been defined as a function
of bus voltage and line flow limit violations. Validity of
proposed architecture is demonstrated by the results obtained
from an intensive experimentation using the benchmark IEEE
57 bus test system. The proposed framework, which is scalable,
can be further extended to intelligent monitoring and control
of power system
Reliability Prediction of Port Harcourt Electricity Distribution Network Usin...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Theoretical work submitted to the Journal should be original in its motivation or modeling structure. Empirical analysis should be based on a theoretical framework and should be capable of replication. It is expected that all materials required for replication (including computer programs and data sets) should be available upon request to the authors.
The International Journal of Engineering & Science would take much care in making your article published without much delay with your kind cooperation
Predicting Post Outage Transmission Line Flows using Linear Distribution FactorsDr. Amarjeet Singh
In order to design and implement preventive
and remedial actions, a continuous performance of fast
security analysis is imperative amid outages of system
components. Following the contingency of a system
component, State estimation and Load flow techniques
are the two popular techniques used to determine
system state variables leading to estimation of flows,
losses and violations in nodal voltages and transmission
line flows. But the dynamic state and complexity of the
system requires faster means of estimations which can
be achieved by linear distribution factors. The use of
Distribution factors in form of Power Transfer
Distribution Factors (PTDF) and Line Outage
Distribution Factors (LODF) which are transmission
line sensitivities with respect to active power exchanges
between buses and transmission line outages offer an
alternative to these two techniques being linear,
quicker, and non-iterative. Following the estimation of
the linear distribution factors from a reference
operating point (base case) and contingency cases
involving line outage, generator output variation and
outage of a Six bus network using Matlab programs,
the results show that by means of Linear Distribution
factors quick estimates of post outage line flows can be
made which match flow results obtained from DC load
flow analysis.
Power System Contingency Ranking Using Fast Decoupled Load Flow Methodpaperpublications3
Abstract: Voltage instability is the phenomena associated with heavily loaded power systems. It is normally aggravated due to large disturbance. The Power system security is one of the significant aspects, where the proper action needs to be taken for the unseen contingency. In the event of contingency, the most serious threat to operation and control of power system is insecurity. Therefore, the contingency analysis is a key for the power system security. The contingency ranking using the performance index is a method for the line outages in a power system, which ranks the highest performance index line first and proceeds in a descending manner based on the calculated PI for all the line outages. This helps to take the prior action to keep the system secure. In this paper Fast Decoupled power flow method is used for the power system contingency ranking for the line outage based on the Active power and Voltage performance index. The ranking is given by considering the overall performance index, which is the summation of Active power and voltage performance index. The proposed method is implemented on a IEEE-14 bus system.
Contingency plans based on N - 1 and N - 2 contingencies are already very much used by utilities . Artificial intelligent methods are new trends for analysing the contingency scenario along with state of art congestion management. This gives extra backup and b oost to reliable operation under contingent scenario of power system. This paper envisages the summary of all those efforts. This paper will help utilities to put more thinking in terms of recent developments in fast and intelligent computing methods. The paper highlights classical research and modern trends in contingency analysis such as hybrid artificial intelligent methods. Steady state stability assessment of a power system pursues a twofold objective:first to appraise the system's capability to withs tand major contingencies,and second to suggest remedial actions,i.e. means to enhance this capability,whenever needed. The first objective is the concern of analysis,the second is a matter of control.
This chapter deals with the reliability analysis of different power system parts which includes the generation, transmission and distribution systems. This slide is specifically prepared for ASTU 5th year power and control engineering students.
Power Flow Analysis of Island Business District 33KV Distribution Grid System...IJERA Editor
The solution to power flow is one of the most important problems in electrical power systems. Traditional methods have been previously used for power flow analysis, but with prevalent drawbacks such as abnormal operating solutions and divergences in heavy loads. This paper presents power flow analysis in a power system, by modelling a typical 33kV Distribution Network, and simulating using the NEPLAN software for power flow studies. Island Business Unit’s (IBU) 33kV network of Eko Electricity Distribution Plc (EKEDP) for a scenario day is taken as case study in the analysis. The most important parameters of power flow analysis is utilized to find the magnitude and phase angles of the voltages at each Busbar, as well as the real and reactive power flowing through each distribution line within the network under consideration.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability
Efforts made in many countries to stop the COVID-19 pandemic include vaccinations. However,
public skepticism about vaccines is a pressing issue for health authorities. With the COVID-19 vaccine
available,
SARS-CoV-2, as the causative agent of COVID-19, has spread throughout the world after becoming
a pandemic in March 2020. In the midst of the ongoing COVID-19 pandemic, we are also faced with another
serious health problem
This paper discusses the construction and implementation of a system for the measurement of
electrical power parameters; amperage and voltage of the hybrid system photovoltaic solar-wind, to evaluate
the system parameters and performance. The basis of the development of the measuring apparatus is the use of
an Arduino Mega 2560 to provide the interface between the electrical circuits of the sensors and the dynamics
of the voltage-amperage as well as collect data in an analog format as well as development of functional
dependence relationships. The collected data is converted into digital format and stored it in an Excel format
through the "PLX-DAQ Spreadsheet" that connects the Arduino and the PC for display and analysis of the
system parameters. The proposed technique for power measurements of AC and DC proved to be reliable and
can predict the power amperage and voltage within relative error of 1.63 % for AC and 4.16% for DC,
respectively.
The optimum speed required for mass-size reduction of shells to produce most sizes that are small
comparable with kernel sizes; coupled with retention of kernel wholeness in cracked palm nut mixture under
repeated impact was investigated. This is to enhance whole kernel separation by dry method, reduce maintenance
and production cost of palm kernel oil (PK0); and lower the risk of oil rancidity associated with split kernel
production and wet method of separation. A static nut cracker and centrifugal nut cracker were used in this study as
Test Rigs while sieves were used to grade cracked shells and whole kernels. The data generated were evaluated. A
model was developed for energy via speed required to retain kernels wholeness following repeated impact in the
crackers. Technical analysis revealed that the maximum allowable speed to retain kernel wholeness is 27.93 m/s;
the minimum allowable average speed to fragment cracked shells is 24.95 m/s. Further analysis showed that the
optimum speed and energy required for cracked nut mixture under repeated impact to have kernel wholeness
retention and production of small sizes of cracked shells relative to kernel sizes are 25.71 m/s and 0.4 J,
respectively.
This review was written to provide a comprehensive summary of the suggested etiologies of Chronic Kidney
Disease of Unknown Etiology (CKDu) in Sri Lanka. In this review, Chronic Kidney Disease (CKD) is explained
in detail and its known etiologies are discussed. CKDu is defined and its epidemiology is discussed, with the
compilation of statistic from over 15 research papers through the years 2000 to present.
This work contributes to the monitoring of water pollution of some selected Dams in Katsina
State, North western Nigeria by assessing the degree of heavy metal pollution in the Dams sediment samples.
The study was conducted in the year 2017 within some selected Dams in the State (Ajiwa, Zobe,
Sabke/Dannakola) that are beehives of fishing and Agricultural activities in Katsina State. Analysis for the
concentration of these heavy metals; Cr, Cd, Fe, Ni, Mn, Pb and Zn was conducted by the use of AAS (by
Atomic Absorption Spectrophotometry) method. Several indices were used to assess the metal contamination
levels in the sediment samples, namely; Geo-accumulation Index (Igeo), Enrichment Factor (EF),
Contamination Factor (CF), Degree of Contamination (Cd), Pollution Load Index (PLI) and Potential
Ecological Risk Index (PERI). The result of this study has shown that generally among the heavy metals
evaluated, the highest concentration was observed for Fe (range: 2.6718-4.2830 ppm), followed by Zn (range:
0.4265-0.7376 ppm), Cr (range: 0.1106-0.1836 ppm), Cd (range: 0.1333-0.1273 ppm) and Mn (range: 0.1136-
0.1271 ppm). While Pb has the lowest concentration (range: 0.0472-0.0598 ppm). For all the site sampled the
heavy metal Ni was below detection level (BDL). From the results of heavy metals I-geo values, according to
Muller’s classification, all the sediment samples from the selected dams were unpolluted (class 0). The result for
the enrichment factor has shown that for all the selected dam sediment samples the heavy metals show
deficiency to minimal enrichment. Also based on the contamination factors for all sediment samples the heavy
metal Cd has a CF values range of 0.5430-0.6665 (~1), indicating that the sediment samples are moderately
contaminated with Cd. In contrast, the rest of the heavy metals exhibit low contamination in general. The value
of PLI ranges from 0.2408 to 0.4935, indicating unpolluted to moderate pollution. The Eri values for all
samples are all < 40, presenting low ecological risk. The results suggest that the sediment samples from the
selected dams in Katsina state has low contamination by the heavy metals evaluated.
Using QR Decomposition to calculate the sum of squares of a model has a limitation that the number of rows,
which is also the number of observations or responses, has to be greater than the total number of parameters used in the
model. The main goal in the experimental design model, as a part of the Linear Model, is to analyze the estimable function
of the parameters used in the model. In order not to deal with generalized invers, partitioned design matrix may be used
instead. This partitioned design matrix method may be used to calculate the sum of squares of the models whenever the total
number of parameters is greater than the number of observations. It can also be used to find the degrees of freedom of each
source of variation components. This method is discussed in a Balanced Nested-Factorial Experimental Design.
Introduction:It has been proven twice that the Hambantota District has the highest life expectancy in male
population. This study focused to find and identify reasons for Hambantota District people to have high life
expectancy at birth.
Methodology: Research was carried out in both qualitative and quantitative phases in five MOH (Medical
Health Officer) divisions in HambantotaDistrict. Study focused on 3 age categories, 55-65 Years, 66-75 Years,
and above 76 Years. Main objectives and key information areas are Life Style and Social Behaviors, Food
Consumption and Diet, Familial Trait and Physical and Mental Health.
Findings: Majority of the male population have educated up to grade 5and most are engaged in the agriculture
while others engaged in fishery and self-employment etc. Almost everyone reachestheir workplaces by foot or by
bicycle. Many of them work less than six hours. They spend their free time with their family members and watch
TV. Most of them do not consume alcohol and smoke. Almost everyone take part in social activities. Majority eat
red rice for all three meals. Almost everyone eats fish every day. They have a high salt intake. Their parents and
ancestors have also have had a high life expectancy. Only a minority suffer from chronic illnesses. They all have
a good physical and mental health condition. They spend happy and relaxed lifestyle.
Conclusion: Healthy diet, low alcohols consumption and smoking, high iodine intake, physical activeness and
their social wellbeing effect for high life expectancy within the male population of selected five MOH divisions
in Hambantota District. They have a free and happy life. Genetics of these people also may contribute for high
life expectancy. Abundance of neem trees in this area also may effect on their high life expectancy.
A clay deposit in Chavakali of western Kenya was evaluated for its potential as refractory raw
material. The collected clay sample was crushed, sieved and the chemical composition determined in
percentage weight (wt %) of (SiO2, Al2O3, Fe2O3, etc) using Atomic Absorption Spectrophotometer (AAS). The
samples were moulded into rectangular shaped bricks of 40mm height, 40mm width and 80mm length, allowed
to dry and later fired up to a temperature of 10000C. Refractory properties like Compressive strength,
Hardness, Linear shrinkage on firing, Apparent porosity and Density were determined using standard
techniques. The result of chemical analysis indicated that the clay was composed of Silica (SiO2), 67.3%;
Alumina (Al2O3), 16.67%; Iron Oxide (Fe2O3), 3.87%; Calcium Oxide (CaO), 0.37%; Potassium Oxide (K2O),
2.30%; Sodium Oxide (Na2O), 1.39%; and other traces. The physical and mechanical tests show that the clay
has Cold Crushing Strength of 10.36MPa, Hardness of 40.080 GPa, Linear shrinkage of 6.17%, Apparent
Porosity of 32.71% and Bulk Density of 2.77g/cm3
. Chavakali clay can make better local refractory
Nihon University challenged world record of the human-powered aircraft flight based on the
regulation of Fédération Aérionautique Internationale in Kasumigaura Lake, Japan, 2014. The wing fell off in
midair immediately after take-off, the pilot landed to the lake for safety. So, the challenge failed. It guessed the
operational errors were correlated with the wing falling in midair, which had not happened in our experience.
The flight recording camera and the salvaged airplane were investigated. The fault tree analysis was conducted
for cause investigation. The wing falling was the result as the chain destruction starting from the coupling parts
being damaged in take-off. The defective take-off was caused by composite factors on only operational errors.
The risk that the ultralight airplane might disintegrate in midair by only operational error became apparent.
Due to the large-scale exploitation of mineral resources and the unreasonable human activities, the
geological disasters in Jiaozuo City have become increasingly prominent and the degree of harm increased. This
leds to a tremendous threat to human life and property safety. Jiaozuo City, the main types of geological
disasters, landslides, ground subsidence, debris flow and ground fissures. It has great significance to the
development of the city and the protection of people's life and property to explore the hidden dangers of
geological disasters and actively take preventive and control measures. The establishment of geological
hazard group measurement system of prevention and control to achieve the timely detection of geological
disasters, rapid early warning and effective avoidance.
Dangerous gas explosion accidents result in considerable amount of casualties and property damage.
Hence, an investigation on the generation of poisonous gases in gas explosions exerts important implications
for accident prevention and control and in the decision-making processes of fire rescue. Therefore, a gas
explosion piping test system is established in this paper. Experimental research on gas explosion is conducted by
selecting methane/air premixed gases with concentrations of 7%, 9%, 11%, 13%, and 15% in the gas explosive
range. This research aims to reveal the regularity of CO generation after gas explosion in pipelines.
Experimental results showed that when the gas concentration is small (< 9%), 1500–3000 ppm CO will be
produced. When the gas concentration is large (> 9%), the CO amount will reach 3000–40000 ppm. The
variation trend in CO concentration and the quantity of explosive gas are also obtained.
To evaluate the influence of the entry speed to flow field above the water surface on an object
high-speed entering into water, the flow field was measured experimentally by using an optical visualization
method. The entry speed was ranging from 0.2 to 1.5 km/s. In case that the entry speed was higher than the
sound speed of gas above the water surface, the vertical velocity of the tip of a water splash was linear to the
vertical location of the tip. The ratio between the initial vertical velocity of a water splash and the entry speed
was independent from the entry speed and was constant.A shock wave was driven above the water surface by the
entry even thoughthe entry speed was lower than the sound speed of gas above the water surface.A scaling law
for the propagation of a shock wave driven by explosion of an explosive was applicable to the propagation of
the shock wave driven by the water entry by using the kinetic energy of the entry object instead of the explosive
energy.
Pingdingshan Coal Mine district is one of the six mining areas of Henan Province, which is a
large coal base in China. After 60 years of exploitation, it has brought great benefits, at the same time,
serious geological disasters have been occurred. It has seriously damaged the normal production of the
masses, life, restricting the development of Pingdingshan coal mine economy. In this paper, the
geological disasters such as ground collapse, ground fissures and ground subsidence in Pingdingshan coal
mine are analyzed, and the degree of geological disasters in the mining area is analyzed in combination
with the severely affected mining area. Finally, reasonable and feasible countermeasures have been put
forward.
Kelud volcano is located in East Java Province, Indonesia. According to Geochemical study of
Kelud Volcano, it could be divided into 3 periods which are Kelud I (older than 100 ky BP), Kelud II (40 – 100
ky BP), and Kelud III (younger than 40 ky BP). A specific petrogenesis of Kelud are dominatad by magma
mixing and fractional crystalization. New petrological data from Kelud volcano was taken through products of
the eruption in 1990 (Vulkanian type), 2007 (Lava plug forming) and 2014 (Plinian type). Petrographic study
on these rocks showed that reverse and oscilatory zoning on plagioclases, Shieve-like and corroded textures on
plagioclases and pyroxenes are common. However, normal zoning textures were also found on plagioclases and
pyroxenes. Whole rock study on these rocks showed all rocks were classified into Basalt to Andesite in
composition with calc-alkaline group. The study indicated that their magma origin derrived from slab with
fractional crystallization during in the magma reservoir, and magma mixing processes are dominant expecially
in magma pockets. Concequently, the magma origin and petrogenesis of Kelud magma after the 1966 eruption
are still the same as those of old magma of Kelud.
Black cotton soils are among a group of soils termed as problematic soils. These soils have
undesirable characteristics in relation to construction works and therefore need some form of improvement
when encountered in construction projects. Techniques for improvement of black cotton soils include
replacement, moisture control or adding a stabilizer. Cement and/or lime has been commonly used in soil
stabilization for ages. However, due to the associated cost, required quality control and the need to utilize waste
materials in construction, new stabilizing materials are emerging. This paper presents a study on application of
quarry dust for improving properties of black cotton soil in Mbeya region, Tanzania. The targeted improvement
was to achieve minimum acceptable characteristics for road subgrade as per Tanzania standards. It was
determined that 40% by weight of quarry dust added to the black cotton soil was able to improve the
characteristics by increasing CBR value from 3.8 to 15.7 and reducing PI from 32% to 15%. It will be worthy
studying the cost implication of the suggested improvement in relation to other techniques before application of
the study findings.
High intensity rain and morphometri in Padang city cause at Arau. Morphometri
geomorphologi that is related to wide of, river network, stream pattern and gradien of river. The form wide
of DAS will be by stream pattern and level.This will influence to the number of rain. Make an index to
closeness of stream depict closeness of river stream at one particular DAS. Speed of river stream influenced
by storey, level steepness of river. Steepness storey, level is comparison of difference height of river
downstream and upstream. Ever greater of steepness of river stream, excelsior speed of river stream that
way on the contrary. High to lower speed of river stream influence occurence of floods, more than anything
else if when influenced by debit big. By using rainfall from year 2005 to year 2015, and use Thiessen method
got a rainfall. Use the DEM IFSAR, analysed sofware ARGIS, and with from earth map, the result got DAS
in at condition of floods gristle and sedimentation. There are band evakuasi for resident which data in
floods area.
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of tissues of Ricinodendron heudelotii (Baill, Pierre ex Pax), an angiosperm, were investigated for its potential
as a fibrous raw material for pulp and paper production. Bolts of about 70 cm were cut from the felled trees at
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outerwood samples. The fiber characteristics of the selected trees viz: the fiber length, fibre diameter and lumen
diameter were measured while the cell wall thickness was derived from the measured fibre dimensions. The
average fiber length, cell wall thickness, and lumen width, were 1.40 mm, 4.6 µm, and 32.3 µm, respectively.
The extractive and lignin contents were determined. Klason lignin content was about 30%. Extractive content of
R. heudelotii ranged from 0.41 to 0.5%. Based on these findings R. heudelotii is suitable for pulp and paper
production.
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the basin lies within deeper plays which are high pressure and high temperature (HPHT) targets. One of the
main characteristics of the Niger Delta is its unique diachronous tripartite stratigraphy. Its gross onshore and
shallow offshore lithostratigraphy consists of the deep-seated Akata Formation and is virtually exclusively
shale, the petroliferous paralic Agbada Formation in which sand/shale proportion systematically increases
upward, and at the top the Benin Formation composed almost exclusively of sand. This stratigraphic pattern is
not exactly replicated in the deep offshore part of the delta.
A low-carbon steel wire of AISI 1022 is used to easily fabricate into self-drilling tapping screws,
which are widely used for construction works. The majority of carbonitriding activity is performed to improve
the wear resistance without affecting the soft, tough interior of the screws in self-drilling operation. In this
study, Taguchi technique is used to obtain optimum carbonitriding conditions to improve the mechanical
properties of AISI 1022 self-drilling tapping screws. The carbonitriding qualities of self-drilling tapping screws
are affected by various factors, such as quenching temperature, carbonitriding time, atmosphere composition
(carbon potential and ammonia level), tempering temperature and tempering time. The quality characteristics of
carbonitrided tapping screws, such as case hardness and core hardness, are investigated, and so are their
process capabilities. It is experimentally revealed that the factors of carbonitriding time and tempering
temperature are significant for case hardness. The optimum mean case hardness is 649.2HV. For the case
hardness, the optimum process-capability ratio increases by about 200% compared to the original result. The
new carbonitriding parameter settings evidently improve the performance measures over their values at the
original settings. The strength of the carbonitrided AISI 1022 self-drilling tapping screws is effectively improved.
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Reliability Assesment of Debremarkos Distribution System Found In Ethiopia
1. International journal of scientific and technical research in engineering (IJSTRE)
www.ijstre.com Volume 1 Issue 1 ǁ April 2016.
Manuscript id. 626565888 www.ijstre.com Page 27
Reliability Assesment of Debremarkos Distribution System Found
In Ethiopia
Demsew Mitiku Teferra1
, Amache Jara Godobo2
Department of Electrical and Computer Engineering
Debre Markos University
Debre Markos, Ethiopia
Abstract- This research presents a method for reliability assessment considering the 23MVA, 230/15 kV
transformer through two 15 kV outgoing transmission lines at Debre Markos substation. It also goes further to
include 139 low voltage 15/0.4 kV distribution transformers. The total load connected to the 15 kV feeders are
varies between 0.33255 and 6.3185 MW. A composite system adequacy and security assessment is done using
Monte Carlo simulation. The basic data and the topology used in the analysis are based on the Institution of
Electrical and Electronics Engineers - Reliability Test System and distribution system for bus two of the IEEE-
Reliability Bus bar Test System. The reliability indices SAIDI, SAIFI, CAIDI, EENS, AENS, ASAI, ASUI, and
expected interruption costs are being assessed and considered. Distribution system reliability information was
obtained from actual data for systems operating in Ethiopia Electric Utility office and Debre Markos substation
recorded data and online SCADA system.
Keywords: Adequacy, DigSILent, Expected Interruption cost, Failure rate, Forced outage, Indices, Interruptions,
Reliability, Repair time, Security.
I. INTRODUCTION
The electric power systems can be divided into generation plant, generation sub-station, transmission
system, sub-transmission and distribution sub-stations. Traditionally, generation is to supply the power to the
transmission system which can be defined as the carrier of power from the generating stations to the sub-
transmission system, at voltage levels of 230 kV or higher. The sub-transmission system then transfers the
power at voltage levels between 66 kV to 132 kV to the distribution substation systems. Finally, the distribution
substation system, at voltages under 33 kV, delivers electricity to the consumer [1].
The case study of radial distribution system reliability assessment is carried out on Debre Markos Substation
system which consists of 66kV, 33kV and 15kV outgoing feeder network in Debre Markos. The reliability
assessment analysis through 230/15KV, 23MVA transformer is done on two 15kV feeders (feeder-3 and feeder-
4) system to assess the performance of existing system to reliability indices analysis considering customer and
system configurations. The alternative technique which shows reliability indices such as SAIDI, SAIFI, CAIDI,
EENS, and EIC are being assessed and considered. Recent and unpublished important information and data have
been collected from Debre Markos Substation. Interviews with respective professionals at substations and
Electric utility office have been considered. The collected data are; fault statics, outage consequences, the
number of interruption, interruption duration, the existing distribution network capacity, the capacity of power
supplied to the network, the number of connected feeders, the minimum, mid-range, maximum demands per
day/month/year, the distance from the transmission line to the distribution, and from distribution to main feeders
of the study area have been collected from Ethiopia electric power and Ethiopia electric utility offices. The
distribution system model for reliability analysis using DIgSILent software tool was developed.
This study considered the two 15kV outgoing feeders (Debre Markos line 3 and line 4) in the town. This is
because the distribution system is the major contributor of the reliability problems in the power system more
than 80% [2].
2. Reliability Assesment Of Debremarkos Distribution System Found In Ethiopia
Manuscript id. 626565888 www.ijstre.com Page 28
Figure 1.1: Basic power system structure.
2. SYSTEM MODEL
2.1. Distribution system Reliability Indices
The most commonly used reliability indices of distribution systems are statistical aggregations of reliability data
for defined loads, components or customers. They are mostly average values of a particular reliability
characteristic for an entire system, operating region, distribution service area or other portion of the system. The
indices can be categorized as customer based and load based indices [3-6].
2.1.1. Customer Based Indices
System Average Interruption Frequency Index: (SAIFI) is measure of how many sustained interruptions on
average customer will experience over the course of a year. For a fixed number of customers, the only way to
improve SAIFI is reduce the number of sustained interruption experienced by customers [3-6].
SAIFI
Total number of customer interruptions
λi Ni
(1)Total number of cutemer served Ni
System average interruption duration index: (SAIDI) is a measure of how many interruption hours on
average customer will experience over the course of a year. For a fixed number of customers, SAIDI can be
improved by decreasing the number of interruptions or by decreasing the duration of these interruptions. Since
both of these reflect reliability improvements, a reduction in SAIDI means an improvement in reliability [3-6].
SAIDI
Sum of customer interruptions durations
Ui Ni
(2)
Total number of customer Ni
Customer average interruption duration index: (CAIDI) is a measure of how long an average interruption
lasts, and is used as a measure of utility response time to system incidents. CAIDI can be improved by
decreasing the length of interruptions, but can also be decreased by increasing the number of short interruptions.
As a result, a decrease in CAIDI does not necessarily mean an improvement in reliability [3-6].
CAIDI
Sum of customer interruptions durations
Ui Ni
(3)Total number of customer interruptions λi Ni
3. Reliability Assesment Of Debremarkos Distribution System Found In Ethiopia
Manuscript id. 626565888 www.ijstre.com Page 29
Average service availability index: (ASAI) is the customer-weighted availability of the system and provides
the same information as SAIDI. Higher ASAI values means higher level of system reliability [3-6].
ASAI
Customer hours of available service
8760
Ni
Ui Ni
(4)
Customer hours demand
8760
Ni
Average service unavailability index:
ASUI
Customer hours of unavailable service
Ui Ni
(5)
Customer hours demand
8760
Ni
Where Ni is the number of customers for load point i,U i is the annual outage duration for
load point , λi is the number of occurrence of sustained interruption at load point i and 8760
is the number of hours in a calendar year [3-6].
2.1.2. Load and Energy Based Indices
One of the important parameters required in the evaluation of load and energy based indices is the average load
La at each load point bus bars, which is given by: [3-6]
La
Lpeak f
Where;
Lpeak is the peak load demand
f is the corresponding load factor
Expected Energy Not Supplied Index at Load Point:
EENS = Expected total energy not supplied by the system = Ui La(i)
Average Energy Not Supplied:
Total energy not supplied
i
AENS
U La(i)
i
Total number of customers served
N
2.2. Software Implementation Procedure for Reliability Evaluation
DIgSILent is a computer aided engineering tool for the analysis of industrial, utility, commercial, and residential
electrical power systems. It has been designed as an advanced integrated and interactive software package
dedicated to electrical power system and control analysis in order to achieve the main objectives of planning and
operation optimization.
DIgSILent reliability evaluation software can be used to provide not only the reliability indices for both the
individual load points and the overall power system, but also it can be used to provide the cost of interruptions.
DIgSILent is based on Monte Carlo simulation and enumeration techniques. Figure 2.1 shows the reliability
evaluation procedure taken in DIgSILent to achieve the reliability indices for both load point and the overall
system.
The first step is to analyze all the input data required for power flow analysis and data required for reliability
evaluation. After processing the data and solving the power flow program for the system in order to obtain the
system characteristics in normal condition, the system will be modeled by applying the MCS. The achieved
model will be reduced to the reasonably small model by applying the contingency and ranking or the truncation
of states techniques. But applying such techniques require a deep understanding over practical systems i.e. it is
necessary to know what kind of outages may occur in practical system. In DIgSILent
4. Reliability Assesment Of Debremarkos Distribution System Found In Ethiopia
Manuscript id. 626565888 www.ijstre.com Page 30
the predefined outages events are categorized in two groups’ i.e. first order and second order contingencies.
Process of Distribution Network Data
Creating possible outage events combinations
1st
order outages events 2nd
order outage events
Single stochastic Single deterministic Double stochastic Single stochastic &
outage outage outage deterministic outage
Effect analysis of each outages mode on system performance
Normal√
System
performance
Abnormal?
Alleviating the abnormality of the system
Normal√ System
performance
Abnormal?
Load curtailment
Σ Registering the failure rate
Load point indices, failures frequency, duration, etc
Overall system indices
Figure 2.1: Flow chart for reliability evaluation of the distribution system
5. Reliability Assesment Of Debremarkos Distribution System Found In Ethiopia
Manuscript id. 626565888 www.ijstre.com Page 31
The second step is to create a first order and second order outage combinations. First order contingencies deal
with single stochastic outages and single deterministic outages. Generally the single deterministic group does
not contribute in interruption frequency while it causes no supply interruption to the loads of the system. Single
stochastic outages group includes several modes such as independent single outage, common mode outage,
ground fault and unintended switch opening. The reliability input data for these categories are failure rate and
repair time and the output data are failure frequency and its relevant duration.
2.3. Case Study Reliability Assessment
To get some insight in the problems related to operation of a real distribution network, a case study based on the
distribution system around Debre Markos and 15km South from Debre Markos town has been performed. The
basis for the study is firstly a steady state load flow model of the 15 and 0.4 kV network which has been created
and is maintained by the distribution network operator, and secondly measurements from the supervisory control
and data acquisition system (SCADA) of the distribution system.
The substation supplies 10670 customers. The utility owns the distribution lines at 66, 33, 15 and 0.4 kV levels.
The grid is only connected to the transmission system through the 230/66 kV, 230/33 kV and 230/15 kV
substation. There are two parallel connected 400/230 kV, another 230/33kV and a third three winding
230/66/15kV transformer stations. This research considers only the 230/15 kV transformer through two 15 kV
outgoing feeders and it also 139 total low voltage distribution transformers.
The 66, 33 and 15 kV system consists of overhead transmission lines, but 0.4 kV systems are considered a part
of the loads. A general one line diagram of the 66, 33 and 15 kV grid including the neighboring 230 kV lines
and the 400 kV in feed is shown in Figure 2.3. The 15 kV network is operated as radials and the total capacity
of 230/66/15 kV transformer is 63MVA supply to two 66 kV (FINOTE SELAM and BICHENA) and supply to
four 15kV (AMANUAL line 1, LUMAME line 2, Debre Markos Line 3 and Debre Markos Line 4) outgoing
feeders. The total load connected to the two 15 kV feeders (Debre Markos Line 3 and Debre Markos Line 4) are
varies between 0.33255 and 6.3185222 MW.
Figure 2.2: ETAP-Model Single line diagram of Debre Markos Substation
6. Reliability Assesment Of Debremarkos Distribution System Found In Ethiopia
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2.4. Distribution Substation test system
The base case distribution system modeled with ETAP software is shown in Figure 2.2. The peak loading levels
of the two feeders (feeder-3 and feeder-4) is 6.31852MW and the average load is 2.972MW. It is assume a
100% of reliability performance from generation and transmission of the RBTS. There is one 230KV main bus
that corresponds to bus 2 from Figure 2.3: which is connected to the 15KV supply point through substation
transformer. Though the 15KV feeder the power supply is limited by having only one 23MVA, 230/15KV
transformer capacity, there are four main feeders, Amanuel line 1, Lumame line 2, Debre Markos line 3, and
Debre Markos line 4 at 15 KV, the feeders operate as radial system.
The main feeder names, detail transformers numbers, ratings, connected numbers of customers and remarks of
low voltage outgoing feeders are shown in Table 2.1. The distribution system has 12 load points that supplies
power to different types of costumer’s loads, such as residential, commercial and industrial, the customers,
minimum load, peak load and average load data at each feeder is shown in Table 2.2.
Figure 2.3: The Base Case Distribution Substation Model Using DIgSILent.
The minimum and maximum recorded load profile of feeder-3 and feeder-4 is presented in Figure 2.3 and
Figure 2.4 in the year 2015.
Load(MW)
Peak load Minimum load
3.5
3
2.5
2
1.5
1
0.5
0
7. Reliability Assesment Of Debremarkos Distribution System Found In Ethiopia
Manuscript id. 626565888 www.ijstre.com Page 33
Sept. Oct. Nov. Dec. Jan. Feb. March April May June July Aug.
Months
Figure 2.3: Peak and Minimum Load Profile of Feeder Three (Debre Markos Line-3)
Load(MW)
3.5
3
2.5
2
1.5
1
0.5
0
Peak load Minimum load
Sept. Oct. Nov. Dec. Jan. Feb. March April May June July Aug.
Months
Figure 2.4: Peak and Minimum Load Profile of Feeder Four (Debre Markos line 4)
2.5. Case Study Area Major Source of Power Interruption
From historical data of the past years, major cause of outages, occurrences, and durations in the system is being
evaluated and presented in Table 2.2 and Table 2.3.
Table 2.2: Causes of outage and number of occurrences in Debre Markos line-3 and -4
Feeder 3 Causes DPEF DPSC DTEF DTSC OP Sum
No. of occurrences 116 74 116 64 320 690
Feeder 4 No. of occurrences 57 45 53 49 242 446
Total number of occurrences 173 119 169 113 562 1136
Table 2.3: Causes of outage and interruption duration in Debre Markos line-3 and -4
Feeder 3 Causes DPEF DPSC DTEF DTSC OP Sum
Interrupted hours 134.9167 178.45 4.467 3.167 298 619.001
Feeder 4 Interrupted hours 142.433 118.1 2.7167 2.033 260.0833 525.366
Total interrupted hours 277.3497 296.55 7.1837 5.2 558.0833 1144.367
8. Reliability Assesment Of Debremarkos Distribution System Found In Ethiopia
Manuscript id. 626565888 www.ijstre.com Page 34
3. SIMULATION RESULT AND DISCUSSION
The DIgSILent software simulation result of reliability indices of Debre Markos substation for each feeders are
shown in Table 3.1, as a radial system with no meshed connections the failure rate (λ/yr), the outage durations
(hr) and annual outage durations (hr/yr) and also Figure 3.1 shows outage duration and failure occurrence of
each feeder.
Outage duration (hrs) Frequency
800
700
648.788044
693.6
600
543.8200008
445.2
500
400
300
200
100
0 Feeder
3 Feeder 4
Figure 3.1: Outage duration and failure occurrence of each feeder.
Table 3.1: Radial system reliability indices for each feeder
Substation Outage Frequency Failure rate λ Annual outage
Feeders duration (hrs) (occurrence) (Failures/year) duration U (hrs/yr)
Feeder 3
648.788044 693.6
0.0855112656 55.478687
Feeder 4
543.820001 445.2
0.0541857652 29.467303
In the normal conditions of the circuit, there are no disconnects on the main line. The only protections are the
fuses that connect the main feeders and the lateral distributors. Hence, any fault on the main line will require the
system to be isolated from the main breaker. The reliability assessment of each feeder can be calculated by
considering the impact of each section and load point on the corresponding load point. Let us to examine the
reliability assessment of each feeder.
9. Reliability Assesment Of Debremarkos Distribution System Found In Ethiopia
Manuscript id. 626565888 www.ijstre.com Page 35
First, the impact of each section failure on the load point’s reliability is considered. Any section failure will
result in power outage for load point since there are no disconnects on the main distribution lines. Then the
outage duration r (hours) of each feeder is assessed. Using the failure occurrences of the feeder, its failure rate λ
(f/yr) is determined. Using the failure rate and repair time, the annual outage duration U (hrs/yr) for each feeder
is obtained.
Secondly, the impact of each lateral distributor’s failure on the load point is considered. Since, each lateral is
connected to the main feeder through fuse; a fault on any lateral will be introducing impact on the other load
point. If there is a fault on the load point, the power from the main feeder is shutdown to repair the fault; its
reliability impact will be added to the system. Adding the impact of each section and lateral distributor, the
average failure rate, average outage duration, and annual outage duration for the main feeders can be calculated
as by using equation (9), (10) and (11).
λs
λi (9)
i
Us
λi ri (10)
rs Us
(11)
λs
From the above equations the other parameters of each feeder were calculated as shown in the Table 3.2.
Table 3.2: The main feeder availability and unavailability indices
S/Station
Ni
648.788 λi ∗ Ni U i
ASAI (%) ASUI (%)
feeder
ri * N
i
Feeder 3 6541 0.085511 559.3294 362886.092 92.594 7.4063
Feeder 4 4129 0.054186
543.82
223.7332 121670.494 93.792 6.208
Total 10670 93.193 6.807
The costumer load point indices are calculated, related to the unsupplied energy and costs. Those are the
expected Energy Not Supplied (EENS), the Expected interruption Cost (EIC) and the Average Energy Not
Supplied values are shown in Table 3.3. The priority order based on the EIC was used for load curtailment level;
the EIC is the average monetary impact on the customers at a load point. This higher the EIC the higher priority
this load may have, because a load curtailment at that load point will contribute to higher economic cost.
Table 3.3: Expected Energy not supplied and Interruption Costs indices for each feeder.
Substation Expected Energy not Expected Interruption Average Energy Not
Feeders supplied (MW hr/yr) Cost EIC (m$ /yr) Supplied (KW hr/yr. ca.)
Feeder 3 1843.73952 1.58043808 281.87426
Feeder 4 1175.52185 1.00764752 284.69892
Total 3019.26137 2.58808558 283.28659
10. Reliability Assesment Of Debremarkos Distribution System Found In Ethiopia
Manuscript id. 626565888 www.ijstre.com Page 36
From the above table each index of the main feeder provides different information and some indices are more
important than others. The main feeder indices are useful in assessing the load point impact of system
modifications and provide input to reliability evaluation at the actual customer level. Furthermore, there are the
system reliability indices which provide valuable information on the overall ability of the system to supply the
customer load. The probability of a customer receiving uninterrupted power supply can be accessed from the
indices of Table 3.2 and Table 3.3. The higher the value of the reliability indices the higher is the unreliability at
the corresponding bus. Using the data from the above table, the overall base case reliability indices can be
calculated as shown in Table 3.4:
Table 3.4: DIgSILent Simulation Result of Overall System Indices Values.
4. CONCLUSION
The result of the study concluded that the base case system indices; SAIDI is 597.476 hr/customer year
suggesting that system’s average interruption duration for each customer is 597.476hr during a year, SAIFI is
608.168 inter./customer year suggesting that system’s average interruption frequency for each customer is
608.168 during a year, CAIDI is 0.982 hrs/ customer interruption, suggesting system’s average interruption
duration for the customers that experience interruption is 0.982 hrs during a year and system availability and
unavailability are 93.193% and 6.803% are respectively . Also, the expected energy not supplied (EENS) for the
base case system due to the failures is 2933.692MWh/yr and the energy not supplied per customer is
168.9396kWh/yr. And finally, the expected interruption cost is 1.5333764millions $/yr during a year. The
system reliability indices show that Debre Markos distribution system is unreliable distribution system.
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