Assessment Of Reliability Indices Research Articles

Distribution network risk assessment with distributed generation impact based on non-sequential Monte Carlo method

At present, the development of renewable energy distributed generation is fast, and the distribution network is facing significant challenges. Unlike traditional fossil fuels, new energy generation is characterized by significant volatility caused by uncertain factors like environmental and meteorological conditions. This paper presents a risk assessment index system that utilizes the non-sequential Monte Carlo method to tackle the given issue. The system comprises two assessments: voltage limit risk and reliability index assessment. Through the application of the Monte Carlo method, a comparative analysis of the results with alternative calculation approaches is conducted. Subsequently, these findings are utilized to evaluate the effectiveness of two commonly employed protection strategies.

Impact of the correlation between random variables on the reliability assessment of the corroded pipelines

In the present work, an Algerian pipeline made of API X70 steel, used for transporting gas and subjected to corrosion attack for three decades, was investigated. Using an intelligent inspection tool, the sizes and orientations of the defects were determined to analyze and improve the accuracy of reliability and/or probability of failure estimates for the damaged pipelines. A probabilistic methodology has been developed to assess the reliability index and the sensitivity of each random variable, within the limit state function, of a gas-transporting steel pipeline that has been corroded for three decades. The reliability analysis utilizes the Second Order Reliability Method, which is based on the BFGS algorithm. In addition, the corrosion defect depth, pipe wall thickness, and corrosion defect length are the most dominant variables within the limit state function, followed by ultimate stress and operating pressure, respectively. Meanwhile, for a failure scenario, thus, it is essential to include a potential parameter such as the correlation coefficient between random variables within the objective function during reliability assessment. For instance, not taking into account the correlation between random variables can lead to an overestimation of the reliability index by 8.89% for a defect depth to wall thickness ratio d/t of 20%. This overestimation increases to 19.16% when the d/t ratio increases to 70%. If the correlation coefficient is significant, it can cause an increase of 8.86% in the error of reliability index assessment for a defect with a depth to wall thickness ratio of 20%, and an increase of 14.58% for a defect with a ratio of 50%. Besides, these avoid the conservative practice resulting from the negligence of the existing correlation between random variables within the limit state function. Hence, considering the correlation coefficients during reliability assessment contributes to setting optimal maintenance schedules for pipelines made of steel under localized corrosion attack.

The Effect Of Distributed Generation (DG) Placement On Electricity Reliability

The continuity of the supply of electric power is becoming a greater demand from consumers. Feeder MRA05 GI Mrica Banjarnegara supplies electrical energy for parts of Banjarnegara Regency until 2020 has 4 distributed generations, namely PLTMH Sigebang 500 KW, PLTMH Kincang 320 KW, PLTMH Adipasir 320 KW, PLTMH Rakit 500 KW. Based on recorded data in 2020, the MRA05 feeder experienced 15 blackouts/year, with a total outage duration of 38.68 hours/year, of course it was enough to disrupt the continuity of the distribution of electrical energy to consumers. This research discusses the magnitude of the reliability index (SAIFI, SAIDI, CAIDI) when the DG is not installed and installed. The calculation of the magnitude of the reliability index was carried out using the Reliability Index Assessment (RIA) method, the calculation results were compared with the results of the ETAP 12.6.0 software simulation. The reliability index is based on the RIA method when DG is not installed, the SAIFI value is 2.96228 interruptions/year, the SAIDI value is 9.1185 hours/year, the CAIDI value is 3.078 hours/interruption, When DG is installed, the SAIFI value is 2.96228 disturbances/ year, the SAIDI value is 7.567 hours/year, the CAIDI value is 2.5546 hours/interruption.

Analisa Keandalan Sistem Jaringan Distribusi 20 kV Dan Rekonfigurasi Recloser Pada Penyulang Kamal

The increasing population in the Kamal area has improved the demand for electrical energy needs. Consequently, disruptions to the electricity distribution network may happen, such as blackouts in certain areas. The value of the reliability index will increase and not be in accordance with the standards that have been set. For this reason, this study calculated the reliability values of SAIFI and SAIDI on the Kamal feeder using the RIA (Reliability Index Assessment) method and the recloser reconfiguration using the fuzzy logic method. The simulation results indicated that the SAIFI value gained 6.331 times/year, while SAIDI obtained 20.212 hours/year. Based on recloser reconfiguration, the SAIFI value was earned 4.926 times/year, whereas SAIDI got 15.962 hours/year. The best location was located on line nineteen in group three, producing an output value of 0.461.

Reliability Assessment of Power Distribution System Using Relative Customer Average Interruptions Duration Index Model

Reliability assessment of power distribution system deals with the adequacy of overall system supply and indicates the system behaviour and response at the customer end. In order to attain satisfactory degree of reliability in electric power distribution system, there is the need to develop a model that will improve the three major system reliability indices via Systems Average Interruptions Duration Index (SAIDI), Systems Average Interruptions Frequency Index (SAIFI) and Customer Average Interruptions Duration Index (CAIDI). This research paper therefore, developed a Relative CAIDI model for assessment of reliability indices of electrical power distribution system. In this paper, ten (10) years outage data from selected distribution feeders of Ibadan, Ikeja and Port-Harcourt distribution systems were obtained and analyzed using curve fitting tools in MATLAB. The system reliability indices served as input parameters for the development of Relative CAIDI model. The best curves that fitted the relationship between the Relative CAIDI and the number of feeders were obtained using Lagrange polynomial functions, Newton polynomial functions and Chebyshev polynomial functions as performance evaluation metrics. The results showed that Ibadan, Ikeja and Port-Harcourt distribution systems had Relative CAIDI of 0.718, 0.3976 and 0.5279 respectively and the validation results produced by Largrange polynomial function, Newton polynomial function and Chebyshev polynomial function were 0.717, 0.3979 and 0.5278 respectively. The model developed is a polynomial of order six which depends majorly on the power requirements of the distribution systems. The developed model can be used for effective reliability assessment of electrical power distribution systems as well as forming a base-line information for system planning and maintenance strategies. Keywords: Reliability Indices, SAIDI, SAIFI, CAIDI, Chebyshev Polynomial Function, Lagrange Polynomial Function, Newton Polynomial Function. DOI: 10.7176/NCS/14-01 Publication date: August 31 st 2022

An Evaluation of Reliability Indices of Selected Nigerian Power Distribution Systems

A system reliability index deals with the quality of overall power supply and indicates the system character during disturbance. The performance of these indices revealed system interruption in terms of the individual customer or organization that’s purchases electric energy at one location under schedule. However, maintaining these reliability indices for electricity operator is very important. Thus, measurement of system reliability indices gives response to operation personnel on reliability effects of operating and maintenance practices. This study therefore, employed the Systems Average Interruptions Duration Index (SAIDI), Systems Average Interruptions Frequency Index (SAIFI) and Customer Average Interruptions Duration Index (CAIDI) for assessment of reliability indices of selected Nigerian power distribution network. Power outage data of Ten (10) were obtained from Ibadan, Ikeja and Port-Harcourt distribution network and analyzed using curve fitting tools in MATLAB. The reliability indices were computed and their means and standard deviations were calculated. The results showed that the reliability indices were effective for reliability assessment of electrical distribution network. Keywords: Reliability Indices, SAIDI, SAIFI, CAIDI, Distribution Network, Means and Standard Deviations. DOI: 10.7176/CEIS/12-3-03 Publication date: November 30 th 2021

Reliability Evaluation of Kumpai Feeder Distribution System at PT. PLN (Persero) ULP Siantan

The research on reliability index of a feeder aims to evaluate the reliability level of a feeder using the Reliability Index Assessment (RIA) method. This method evaluates the reliability of a 20 kV distribution network by calculating the reliability indexes of each load point. The evaluation results show the reliability index value per section of the Kumpai Feeder at PT. PLN (Persero) ULP Siantan within one year. The SAIFI values are 0.0092; 0.0012; 12,477; 0.0596; 0.0204; 0.0470; 0.0155; 0.0728, the SAIDI values are 0.0277; 0.0042; 37,746; 0.1862; 0.0741; 0.1524; 0.0493; 0.2209, the CAIDI values are 3.0108; 3.5; 3,025; 3.1241; 3.6323; 3.2425; 3.1806; 3.0343, the MAIFI values are 0; 5,480; 0.2145; 0.0020; 0.0038; 0.0042; 0.0006; 0.0014. The calculation results show that the 20 kV distribution system at PT. PLN (Persero) ULP Siantan at the Kumpai Feeder can be categorized as unreliable. Because the SAIFI value of this feeder exceeds the standard set by PT. PLN (Persero) which are 12.477 times/customer/year and 3.2 times/customer/year, respectively. The factors affecting the reliability index of the Kumpai feeder are the number and duration of blackouts, the number of customers, and the length of the distribution system channel.

Construction and Evaluation of a Risk Score Model for Autophagy-Related Genes in Esophageal Adenocarcinoma.

BackgroundSeveral studies have suggested the importance of autophagy during esophageal adenocarcinoma (EAC) development. This study aimed to explore the autophagy-related genes correlated with overall survival in patients with EAC.Material/MethodsThe RNA-seq expression profiles and clinical data of patients with EAC were screened using The Cancer Genome Atlas (TCGA) database. Screening of autophagy-related genes was conducted using the human autophagy database (HADb). Bioinformatic analysis was conducted and included the following: univariate cox, lasso regression, and multivariate cox regression analysis; building overall survival assessment of the prognosis model; drawing the model of receiver operating characteristic (ROC) curve and determining the area under the curve; and a C-index reliability index assessment model through Kaplan-Meier screening of statistically significant genes in the model. The screening results were verified via Oncomine differential expression analysis. Gene set enrichment analysis (GSEA) was further used to analyze the molecular biological functions and related pathways of the gene model.ResultsThrough cox regression and ROC analysis, the model showed that the risk score could accurately and independently predict the prognosis of EAC. The screening identified 4 genes: DAPK1, BECN1, ATG5, and VAMP7. GSEA showed that the high and low expression levels of the 4 genes were mainly enriched in biological functions, such as cell production and regulation, and metabolic pathways that maintain cell activity.ConclusionsOur research found that autophagy was involved in the process of EAC development and that several autophagy-related genes may provide prognostic information and clinical application value for patients with EAC.

ANALISIS PERBANDINGAN KEANDALAN SISTEM JARINGAN DISTRIBUSI BERKONFIGURASI RADIAL DAN LOOP MENGGUNAKAN METODE RIA (RELIABILITY INDEX ASSESSMENT)

Electrical energy is a very important requirement for human life. The supply of electrical energy itself consists of electricity generation, power transmission and distribution. In the distribution of electricity, there are several networks that function to distribute electrical energy to customers, the majority of which are network configuration, namely radial and loop. In order to maintain the continuity of the distribution of electrical energy, a good level of reliability is required. In order to determine the reliability of the distribution system, the reliability index is determined, namely SAIFI, SAIDI and CAIDI. Several methods that can be used to find a distribution system reliability index include the RIA (Reliability Index Assessment) method, which is an approach used to predict disturbances in a distribution system based on the system topology and data regarding component reliability. In this study, we compared two configurations using one feeder, namely the Giri feeder which is assumed to have a radial configuration and a loop configuration. By using the RIA (Reliability Index Assessment) method on a Giri feeder with a radial configuration, the SAIFI reliability index is obtained at 1.595 times / year, SAIDI is 12.8092 hours / year, CAIDI is 8.0309 hours / year, while for a feeder with a loop configuration the SAIFI value is equal to 1,651 times / year, SAIDI is 1,7276 hours / year, CAIDI is 1,0416 hours / year.
 
 Keywords ­— Reliability Index, Distribution System, Reliability Index Assessment, SAIFI, SAIDI, CAIDI

Probabilistic analysis of settlements under a pile foundation of a road bridge pylon

The paper addresses the reliability change of a road bridge pile foundation due to the unpredictable increase of settlements in time. The analysis is based on the Rędziński Bridge in Wrocław, Poland, its design assumptions, and monitoring results. The bridge foundation rests on a multi-layered subsoil assumed random. The Finite Element model of the subgrade is generated in ZSoil® software. To simplify the probabilistic approach, substitute soil strata stiffness parameters are adopted. Tracing their time decrement allows for a comprehensive definition of the entire foundation over-settlement produced by numerous factors. Preliminary sensitivity analysis of settlements to the stiffness variation properly simplifies the random model. The Serviceability Limit State helps to assess the foundation reliability index, further compared with the condition in the EN 1990:2002/A1:2005 standard. In addition, real-life settlements are also measured in the first year of bridge operation, they are used to calibrate the reliability index assessment. An innovative approach is proposed, where appropriate time-wise fluctuation functions represent the expected settlement increase and the related reliability reduction. These fluctuation functions help to plan the future remedial actions to maintain the initial bridge safety and to indicate the action frequency and scope. Future reliability levels may be extrapolated too. The real-life survey database of settlements makes it possible to validate the results of probabilistic calculations. A dedicated flowchart is devised to support further analysis of a wide structural domain.

Valuation of Reliability Index in Distribution Network 13.8 kV

This study is proposed to calculate and analyze the level of reliability of the 13.8 kV distribution system. To calculate the reliability index based on the reliability index of the value of the failure that occurred. The method used throughout this study is the Reliability Index Assessment (RIA) when this method takes into account momentary interruption. The distribution network is considered as the object of this study has six feeders. Based on blackout data obtained, the reliability index becomes smaller and can be distinguished between permanent and temporary disruptions. The calculation results show the reliability index of SAIDI, SAIDI, and MAIFI based on the type of disturbance; the results of this calculation will be compared with SPLN and IEEE. A comparison of the results of the calculation of SAIFI values from the six feeders analyzed all meet the SPLN and IEEE rules. However, in one of the feeders, the SAIDI index exceeds the established standard, which is 24 hours/year/customer, with the SPLN regulation being 21 hours/year/customer, and the IEEE standard is 2.3 hours/customer/year. And finally, the results of an analysis of the MAIFI index for all feeders meet the IEEE standard of 5 times/year/customers.

Reliability Analysis of Distribution Network Based on Reliability Index Assessment Method: A Case Study.

A primary requirement of a modern electric power system is reasonable ability to satisfy the customer load requirements. Electric utilities involve generation, transmission, and distribution facilities each one of which contributes its own inherent difficulties to the problem of satisfying customer requirement. A power system should be designed and expanded the facilities in order to perform its intended function with a reasonable risk. With increasing the electrical energy demand and the potential of disruption that may occur in the system, the distribution system must have high reliability and continues supply to customer. In this case, the reliability of the distribution system needs to be evaluated by monitoring and analyzing the level of distribution system failure in a certain period of time. A study on a practical distribution system with application of automatic circuit reclosers (ACRs) which plays an important role in enhancing the reliability index of system is presented. The reliability index assessment analyze the reliability index of the existing system before and after application of ACRs. From the simulation point of view, the system average interruption frequency index (SAIFI) is about 19.43% or decreased the failure frequent event from 11.4 failure/ customer.year to 9.25 failure/customer.year); while the momentary average interruption frequency index (MAIFI) has decreased from 6.72 failure/customer.year to 5.05 failure/ customer.year, or increase the reliability index of about 24.85%.

Reliability index assessment by different methods in the concrete bridges subjected to corrosion

ABSTRACTThe corrosion resulting from carbonation, chloride ion penetration, sulfate attack, etc. causes cracks in the reinforced concrete piles so that they may propagate under the bridge service loads. In this paper, various boundary methods have been employed to determine the probability of failure for bridge systems due to corrosion and compare them to obtain the most accurate method. Therefore, the boundaries proposed in this study are upper and lower than the boundaries of previous studies so that the interval is shrunk about 15%. This reduction may show that probability of failure is estimated more accurately as well as the maintenance management of concrete bridges amends.

A Sensitivity Based Approach for Assessment of Reliability Indices of Electrical Distribution Systems.

In Nigeria, satisfactory degree of reliability has not been attained in the power system in recent times. The average duration of interruptions that customers experience is very high and the degree varies widely especially in urban and commercial cities of the country. This research paper therefore presents the sensitivity analysis of electrical distribution systems. Ten years of outage information from seven major distribution systems – Ibadan, Ilorin, Ikeja, Portharcourt, Kaduna, Kano and Benin were used as input data for computation of the mean and standard deviation for the system reliability indices using statistical analysis. The computed system reliability indices were used as input parameters in the analysis. A sensitivity analysis is performed to assess how the operation parameters could influence the numerical results. The results of the sensitivity studies indicate that Etete feeder of Benin distribution system has the highest SAIDI sensitivity of 0.5478 because of prolonged customers‘ interruptions on the feeder while waterworks feeder of Ilorin distribution system has the least SAIDI sensitivity of 0.0019. Cocoa feeder of Ibadan distribution system has the highest SAIFI sensitivity of 1.0459 because of the frequent interruptions while waterworks feeder of Ilorin distribution system has the least SAIFI sensitivity of 0.0268. Ikpoba Dam of Benin distribution system recorded the highest CAIDI sensitivity of 0.8466 with waterworks feeder also recording the least CAIDI sensitivity of 0.0075. The results from this research paper provides baseline information for planning and managing distribution system on Nigeria national grid. Keywords: Sensitivity, Reliability indices, Distribution systems, SAIDI, SAIFI, CAIDI, Interruptions. DOI : 10.7176/APTA/77-07 Publication date :May 31 st 2019

Reliability Evaluation of Power Distribution System with Reliability Index Assessment (RIA)

Distribution network system reliability is a measure of the level of service of the system of electricity supply to consumers. This study aimed to get some reliability index value of the electricity distribution network system at PT PLN (Persero) APJ Bandung, namely the failure rate, the average output time, the average annual unavailability, SAIFI, SAIDI, CAIDI, ENS and then AENS. These results will be used as a reference for determining the level of reliability of the system. Search reliability index value itself is done by way of basic data recap interference on each unit in the network (UPJ) and then calculating the index of reliability by using formulas reliability index. The results of this study, the value of reliability indices SAIFI on the system 2.02 disorders / customer / year with a target of 1.27 disorders / customer / year, while the reliability index SAIDI on the system 0.28 hours / customer / year with a target of 0.21 hours / customer / year, with these results show electric power distribution network system of PT PLN (Persero) APJ Bandung could not reach the target reliability especially SAIFI and SAIDI. The results of this study are also expected to give an idea of the level of system reliability of electric power distribution network PT PLN (Persero) APJ Bandung.

Improving the Efficiency of Administrative Decision-Making when Monitoring Reliability and Safety of Oil and Gas Equipment

Methodology of rapid assessment of reliability index was developed based on system analysis of technological parameters. Within functioning of on-line monitoring system of reliability index of industrial facility this method allows to increase efficiency of making managerial decisions on technical and preventive maintenance. The technique is based on the analysis of technological parameters of operational modes of pipeline transport facilities registered by dispatcher controls. The created technique can be used by the operating, research, design institutes and oil and gas transport enterprises when declaring industrial safety. The received mathematical models allow federal services of supervision, the independent expert organizations to predict the development of reliability in the registered block of dispatching data either in real time mode, or taking into account the dynamics of service conditions of the object.

An Outage of Overhead and Underground Distribution Network Evaluation Assessment

Frequent and major power interruptions cause many concerns. Assessment of customer power supply reliability is an important part of distribution operation and planning. Many factors are responsible in the reliability of power network; design, construction, operation and maintenance which have their combined effect to overall performance of power network reliability. Analysis of outage data from both OH and UG distribution system of Abuja network is carried out assess their reliability indices. Predictive assessment of distribution reliability indices can be used to identify areas that have poor reliability so that appropriate approach can be taken in the system design and implementation. This paper presents assessment of reliability indices in a practical radial distribution network particularly with the interest of comparison the reliability of OH and UG distribution system. UG is more reliable than OH but takes longer duration in fault restoration.

A Comparative Analysis of Methods of Polynomial Coefficients Determination for Reliability Indices of Ilorin Distribution Systems

Distribution system delivers the transmitted energy to the end users which are customers. This paper develops a generalized polynomial model and compares the coefficients for the assessment of reliability indices of Ilorin distribution system feeders. The results of the coefficients obtained were validated by subjecting the polynomial model to three methods namely: Lagrange Polynomial, Newton and Chebychev Polynomial function methods. The results of the work showed that average values of -7x10 -4 , 0.00212, -0.0256, 0.1549, - 0.4865 and 0.7049 were obtained as the coefficient values from the Lagrange, Newton and Chebychev polynomial function methods which compare favourably well with the coefficient values of -7x10 -4 , 0.0021, -0.0257, 0.1549, -0.4865 and 0.7048 obtained from the simulation results. The

Development of reliability index for cogeneration cycle power plant using graph theoretic approach

A logical approach based on graph theory and matrix method (GTMM) is developed for assessment of reliability index for a co-generation cycle power plant (CGCPP). For a humongous and multipart system such as CGCPP, reliability of its components or subsystems is closely intertwined and insuperable without taking the effect of others. For the ease of analysis CGCPP system is divided into four sub-systems. Reliability of CGCPP is modeled in terms of a reliability attributes digraph which is developed from system reliability digraph. Nodes in the digraph represent sub-system reliability and reliability of interrelations is represented by the directed edges. The digraph is represented by one-to-one matrix called as variable system reliability permanent matrix (VSRPM). A step by step procedure is developed for calculating variable permanent function for reliability (VPF-r) from VSRPM. A higher value of index implies that the plant is available with better reliability. The developed methodology is illustrated step-by-step with the help of an example.

An Effective Simulation Technique to Evaluate Loss of Load Expectation

Risk index of loss-of-load expectation is traditionally used to determine generation adequacy. However, be-cause responsibility of generation installation and demand increases with different entities, both generation and load need to be examined to evaluate the resource adequacy of today’s deregulated power systems. An electric utility’s main concern is to plan, design, operate and maintain its power supply to provide an acceptable level of reliability to its users. This clearly requires that standards of reliability be specified and used in all three sectors of the power system, i.e., generation, transmission and distribution. Reliability indices have been defined for the three sectors separately as well as for the bulk power system. Reliability criteria may be determined at the selected load points in the system for different combination of generators and transmission line failures. This paper presents an effective simulation method for the reliability assessment of reliability index, loss-of-load expectation (LOLE). This method is applied to Bangladesh Power System (BPS). BPS has a total installed capacity of around 6550 MW. The maximum demand of BPS is about 5700 MW. The relevant data of the generators and hourly load profiles are collected from the National Load Dispatch Center (NLDC) of Bangladesh and reliability index ‘LOLE’ is assessed for the last six years.