scholarly journals Reliability of Supply and the Impact of Weather Exposure and Protection System Failures

2020 ◽  
Vol 11 (1) ◽  
pp. 182
Author(s):  
Erlend Sandø Kiel ◽  
Gerd Hovin Kjølle
Keyword(s):  
System Reliability ◽  
Failure Modes ◽  
Extreme Weather ◽  
Test System ◽  
Protection System ◽  
Electrical Transmission ◽  
System Failures ◽  
Reliability Indices ◽  
The Impact

Extreme weather is known to cause failure bunching in electrical transmission systems. However, protection systems can also contribute to the worsening of the system state through various failure modes—spontaneous, missing or unwanted operation. The latter two types of failures only occur when an initial failure has happened, and thus are more likely to happen when the probability of failure of transmission lines is high, such as in an extreme weather scenario. This causes an exacerbation of failure bunching effects, increasing the risk of blackouts, or High Impact Low Probability (HILP) events. This paper describes a method to model transmission line failure rates, considering both protection system reliability and extreme weather exposure. A case study is presented using the IEEE 24 bus Reliability Test System (RTS) test system. The case study, using both an approximate method as well as a time-series approach to calculate reliability indices, demonstrates both a compact generalization of including protection system failures in reliability analysis, as well as the interaction between weather exposure and protection system failures and its impact on power system reliability indices. The results show that the inclusion of protection system failures can have a large impact on the estimated occurrence of higher order contingencies for adjacent lines, especially for lines with correlated weather exposure.

A Simulation and Modeling Based Reliability Requirements Assessment Methodology

2014 ◽  
Author(s):  
Tomonori Honda ◽  
Eric Saund ◽  
Ion Matei ◽  
Bill Janssen ◽  
Bhaskar Saha ◽  
...  
Keyword(s):  
System Reliability ◽  
Failure Modes ◽  
Vehicle Design ◽  
Assessment Methodology ◽  
Exploration Tool ◽  
Design Case Study ◽  
The Cost ◽  
Design Cost ◽  
The Impact

To minimize the design cost of a complex system and maximize performance, a design team ideally must be able to quantify reliability and mitigate risk at the earliest phases of the design process, where 80% of the cost is committed. This paper demonstrates the capabilities of a new System Reliability Exploration Tool based on the improved simulation capabilities of a system called Fault-Augmented Modelica Extension (FAME). This novel tool combines concepts from FMEA, traditional Reliability Analysis, and Quality Engineering to identify, gain insight, and quantify the impact of component failure modes through time evolution of a system’s lifecycle. We illustrate how to use the FAME System Reliability Exploration Tool through a vehicle design case study.

scholarly journals Reliability and protection in distribution power system considering customer-based indices

2021 ◽  
Vol 39 (4) ◽  
pp. 1198-1205
Author(s):  
J.N. Nweke ◽  
A.G. Gusau ◽  
L.M. Isah
Keyword(s):  
Power Supply ◽  
System Reliability ◽  
Distribution System ◽  
Network Performance ◽  
Test System ◽  
Mitigation Strategies ◽  
Reliability Indices ◽  
Electric Power Supply ◽  
Utility Company ◽  
Distribution System Reliability

A stable and reliable electric power supply system is a pre-requisite for the technological and economic growth of any nation. Nigeria's power supply has been experiencing incessant power interruptions caused by a failure in the distribution system. This paper developed a system planning approach as part of the key mitigation strategies for improved reliability and protection of the distribution network. The developed algorithm is tested using 33kV feeder supplying electricity to Kaura-Namoda, Zamfara State,  Nigeria. A customer-based reliability index was used as a tool to evaluate the reliability assessment of the feeder test system. The result showed that alternative 3 gives better results in terms of improvement of the system average interruption duration index (SAIDI), which in turn gives the minimum interrupted energy. Also, it is found that a greater number of sectionalizing switches do not give better results. It is very important to place the sectionalizing switches at a strategic location. If it is located at such points that will facilitate to sectionalize the faulty sections faster and to make the supply available to the unfaulty part of the network. Hence the utility company should apply this mitigation algorithm for system reliability improvement, depending on their needs and requirements. Thus, utilities can optimize network performance and better serve customers by adopting mitigation strategies in addressing trouble-prone areas to achieve a stable and reliable supply Keywords: distribution system; reliability; reliability indices; system performance evaluation; protection system; mitigation algorithms and sectionalizing switches 

Optimal Reliability and Cost of Non-Repairable Systems Subject to Two Failure Modes Considering Correlated Failures

2018 ◽  
Vol 25 (05) ◽  
pp. 1850024
Author(s):  
Anusha Krishna Murthy ◽  
Saikath Bhattacharya ◽  
Lance Fiondella
Keyword(s):  
Failure Mode ◽  
System Reliability ◽  
Failure Modes ◽  
Optimal Number ◽  
Optimal Designs ◽  
Repairable Systems ◽  
Independent Manner ◽  
Reliability Models ◽  
Correlated Failures ◽  
The Impact

Most reliability models assume that components and systems experience one failure mode. Several systems such as hardware, however, are prone to more than one mode of failure. Past two-failure mode research derives equations to maximize reliability or minimize cost by identifying the optimal number of components. However, many if not all of these equations are derived from models that make the simplifying assumption that components fail in a statistically independent manner. In this paper, models to assess the impact of correlation on two-failure mode system reliability and cost are developed and corresponding expressions for reliability and cost optimal designs derived. Our illustrations demonstrate that, despite correlation, the approach identifies reliability and cost optimal designs.

Probability of Uncontrolled External Leakage During the Production Phase of a Subsea Well

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
André L. R. Alves ◽  
T. A. Netto
Keyword(s):  
Failure Modes ◽  
Base Case ◽  
Component Reliability ◽  
Production Phase ◽  
Distribution Parameters ◽  
Common Cause Failures ◽  
Integrity Management ◽  
Closed Position ◽  
The Impact

Abstract This work presents a methodology for evaluating the uncontrolled external leakage probability of a subsea well during the production phase. Based on a barrier diagram, an algorithm for possible leak path identification is proposed, considering different operation modes: gas lift operation, free-flowing, or well closed at the subsea Christmas tree. Considering the equivalency between these paths and the minimum cut sets from a fault tree modeling, the uncontrolled external leakage probability is calculated using the upper bound approximation. The effect of common cause failures is considered for the failure mode fail-to-close-valve. The instantaneous availability function of each component is considered. Non-repairable, repairable, and periodically tested items are used. Probability distribution parameters are estimated in order to make a case study. The failure rate functions determined are used as input for the proposed model, regarding the following failure modes: fail-to-close, external-leakage, and internal-leakage at the closed position. Finally, failure probability results and sensitivity analysis are demonstrated for a base case study. Parameters like time between tests, inspections, and component reliability are varied in order to identify the impact on the uncontrolled external leakage probability. The main objective of the proposed methodology is to support decision-making on the well integrity management system during the production phase of a subsea well. To this end, actual and reliable input data should be considered.

scholarly journals Effective sensor placement based on a VIKOR method considering common cause failure in the presence of epistemic uncertainty

2021 ◽  
Vol 23 (2) ◽  
pp. 253-262
Author(s):  
Rong-Xing Duan ◽  
Jie-Jun He ◽  
Tao Feng ◽  
Shu-Juan Huang ◽  
Li Chen
Keyword(s):  
System Reliability ◽  
Epistemic Uncertainty ◽  
Sensor Placement ◽  
Vikor Method ◽  
Common Cause ◽  
Reliability Indices ◽  
Common Cause Failure ◽  
Dynamic Fault Tree ◽  
Sensor Model

Owing to expensive cost and restricted structure, limited sensors are allowed to install in modern systems to monitor the working state, which can improve their availability. Therefore, an effective sensor placement method is presented based on a VIKOR algorithm considering common cause failure (CCF) under epistemic uncertainty in this paper. Specifically, a dynamic fault tree (DFT) is developed to build a fault model to simulate dynamic fault behaviors and some reliability indices are calculated using a dynamic evidence network (DEN). Furthermore, a VIKOR method is proposed to choose the possible sensor locations based on these indices. Besides, a sensor model is introduced by using a priority AND gate (PAND) to describe the failure sequence between a sensor and a component. All placement schemes can be enumerated when the number of sensors is given, and the largest system reliability is the best alternative among the placement schemes. Finally, a case study shows that CCF has some influence on sensor placement and cannot be neglected in the reliabilitybased sensor placement.

scholarly journals Stochastic Planning and Operational Constraint Assessment of System-Customer Power Supply Risks in Electricity Distribution Networks

2021 ◽  
Vol 13 (17) ◽  
pp. 9579
Author(s):  
Mikka Kisuule ◽  
Ignacio Hernando-Gil ◽  
Jonathan Serugunda ◽  
Jane Namaganda-Kiyimba ◽  
Mike Brian Ndawula
Keyword(s):  
Sequential Monte Carlo ◽  
Network Reliability ◽  
Distribution Network ◽  
Integrated Approach ◽  
Distribution Networks ◽  
Test System ◽  
Electricity Distribution ◽  
Reliability Indices ◽  
Operational Constraints ◽  
The Impact

Electricity-distribution network operators face several operational constraints in the provision of safe and reliable power given that investments for network area reinforcement must be commensurate with improvements in network reliability. This paper provides an integrated approach for assessing the impact of different operational constraints on distribution-network reliability by incorporating component lifetime models, time-varying component failure rates, as well as the monetary cost of customer interruptions in an all-inclusive probabilistic methodology that applies a time-sequential Monte Carlo simulation. A test distribution network based on the Roy Billinton test system was modelled to investigate the system performance when overloading limits are exceeded as well as when preventive maintenance is performed. Standard reliability indices measuring the frequency and duration of interruptions and the energy not supplied were complemented with a novel monetary reliability index. The comprehensive assessment includes not only average indices but also their probability distributions to adequately describe the risk of customer interruptions. Results demonstrate the effectiveness of this holistic approach, as the impacts of operational decisions are assessed from both reliability and monetary perspectives. This informs network planning decisions through optimum investments and consideration of customer outage costs.

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