Failure Of Protection System Research Articles

Review and prospect of hidden failure: protection system and security and stability control system

With the construction of the “3-level, 3-vertical-line, and 1-circle” power backbone in China, it’s stricter and stricter on relay protection system and security and stability control system (SSCS) for reliable power transmission. Lots of blackouts in the world had happened, one main reason for which is the hidden failures of relay protection system or SSCS. Much work had been done about the hidden failure of relay protection, including classification, probability model, analysis methods of effects on power grid, and monitoring measures, which was summarized in the paper. The operation experiences of SSCS indicated that there might be hidden failures in five links of the security and stability control device (SSCD), e.g. measuring, control strategy, setting, communication and voting pattern. In addition, the coordination hidden failure among relay protection system, SSCS, and power plant’s parameters related to the power grid was pointed out for more attention. In the future, amounts of work will be expected to be conducted on hidden failure: model building, assessment methods, application of research achievements, operation management of secondary equipment, and coordination problem between the relay protection system and the SSCS.

KOORDINASI SETTING RELAI ARUS LEBIH PADA INCOMING 2 KUDUS TERHADAP OUTGOING KUDUS 5 DAN 6 YANG MENGGUNAKAN JARINGAN DOUBLE CIRCUIT DI GI 150 KV KUDUS

Sartika Kusuma Wardani, Subali, in paper coordination of flow over relay setting in incoming 2 kudus to outgoing 5 and 6 using double circuit network on GI 150 KV kudus explain that PT PLN make every effort to improve service to customers , one of them by increasing the reliability of the distribution of electrical energy . Reliability of the distribution network is very important for both consumers and PLN. One measure of the reliability of the system / network is a factor SAIDI (System Average Interruption Duration Index) and SAIFI (System Average Interruption Frequency Index). Steps that have been done one way to minimize the possibility of interference is by installing protective devices on medium voltage networks. However, installation of protection equipment is not enough if the relay setting coordination between the incoming and outgoing imprecise. In fact in recent months, an interruption in the feeder distribution network which affects the incoming relay tripnya due to failure of the feeder protection system. One of the events that have happened several times is the same disorder in a double feeder circuit (network supplied from a single source by using two networks ( two feeder ) were included in the bus and in 1 pole) and holy 5 and 6 which causes the incoming PMT trip. It is very risky to happen, because the resulting trip relays at all incoming feeder that gets supply voltage of the incoming. So it takes coordination of overcurrent relay settings right so that the incidence of the incoming trip Sacred 2 does not happen again . Keywords: distribution, protection, relay settings, incoming, outgoing

Risk Assessment in Extreme Events Considering the Reliability of Protection Systems

This paper presents a new risk assessment method that is applicable to extreme cases in power systems. This paper analyzes the interactions among protection system components and the power grid in extreme events pertaining to simultaneous faults and cascading failures. The hidden failures of protection systems could exacerbate power system conditions if cascading events tend to follow a path to a blackout. The proposed risk assessment considers detailed reliability models of protection system components including circuit breakers (CBs) and protective relays. The failure probability of a CB is formulated considering its component degradation rate and operation times. The failure model of a protective relay is constructed using the dynamic fault tree. The evolution of cascading failures of power systems in extreme conditions, which deteriorates due to protection system malfunctions, is modeled based on the actual physical system behavior. The effectiveness of the proposed risk assessment method is demonstrated using a modified 9-bus system and the IEEE 68-bus system.

Evaluation of the impacts of relay coordination on power system reliability

SUMMARY The security and reliability of a power system rely on establishing and maintaining proper coordination among protective relays. In addition to interrupting unnecessary loads, the probability of exposing hidden failures in protection system components such as Circuit Breakers (CBs) may increase as a consequence of miscoordination among relays. In order to evaluate how malfunction of a protection system can degrade the reliability of the system, this paper proposes a new Markov Chain Monte Carlo (MCMC) algorithm. Furthermore, to consider the impact of relay miscoordination on the hidden failure of protection systems, the paper proposes a failure index which is contingent on the magnitude and duration of fault currents. Then, for a sample test system, the reliability indices of SAIDI, EENS, and ECOST are obtained for three scenarios with different relay settings and coordination. The results are then compared to show that how protection miscoordination in medium-voltage networks degrades the reliability level of the system. Copyright © 2014 John Wiley & Sons, Ltd.

Fuzzy Neural Network for Classification Fault In Protection System

Novel intelligent technique is a combination of fuzzy and neural network techniques that can be used to classify faults in electric power system protection. There have two problems in the protection system, which are: undesired tripping and fail to operate. Loss of power supply to relays and circuit breakers or failure in protective devices may cause failures in protection system. Construction of neural networks to explore fact to identify fault component is from control center. The objective of this paper is to develop novel concept for classification failures protection system are using Fuzzy Neural Network technique. Methodology consists of Neural Network and Fuzzy. The Neural network is also conscientious for estimating degree of membership in system components from corresponding area in classification of disorders. The input variables of neural network formed of binary numbers. Value of 1 indicates if fault occurs and value of 0 indicates no-fault occurs. Fuzzy relations will represent by fuzzy. These Fuzzy relations can be represented by fuzzy diagram consisting of three sets of node that would be considered to represent components, relays and circuit breakers.

Reliability Evaluation for Distribution System Including Protection System Failures

A new model and method for incorporating the effect of protection system failures into distribution system reliability evaluation are developed this paper. Firstly, the distribution system is partitioned into zones with the auto (or non-auto) switch being the boundary; through the network equivalent approach, for each load point, three component groups are respectively formed by two types of zone-elements. Then two types of protection failures and their impacts on reliability modeling are discussed. Finally, the reliability Markov model of load point with protection failures has been developed. The test results of the samples demonstrate the practicability and validness of the method.

A METHOD FOR LINKING SAFETY FACTOR TO THE TARGET PROBABILITY OF FAILURE IN FIRE SAFETY ENGINEERING

Ensuring occupants’ safety in building fires is one of the most important aspects for fire safety engineering. Many uncertainties are inevitably introduced when estimating the occupant safety level, due to the high complexity of fire dynamics and the human behaviour in fires. Safety factor methods are traditionally employed to deal with such uncertainties. This kind of methods is easy to apply but leaves fire safety engineers unsure of the margin by which the design has failed. A method of linking safety factor and probability of failure in fire safety engineering is proposed in this study. An event tree is constructed to analyse potential fire scenarios that arise from the failure of fire protection systems. Considering uncertainties related to fire dynamics and evacuation, the traditional deterministic safety factor is considered as a random variable. Because there is no target probability of failure accepted by the whole fire safety engineering community, the concept of expected risk to life (ERL) is integrated to determine the target probability of failure. This method employs a Monte Carlo Simulation using Latin Hypercube Sampling (LHS) to calculate the required safety factor. A practical case study is conducted using the method proposed in this study.

Determination of the optimum routine and self‐checking test time intervals for power system protection considering remote back‐up protection system failure

In this study, routine and self-checking tests are performed as one of the methods to maximise the availability and adequate operation of power system protection. However, optimum routine test time intervals (ORTTI) and optimum self-checking test time intervals (OSTTI) should be determined exactly to anticipate maintenance cost of power system protection precisely. Back-up protection system failure has a vital role in determining precise ORTTI and OSTTI, whereas most of the previous studies have assumed that back-up protection system is perfectly reliable. Therefore in this study, an extended Markov model is proposed to determine the ORTTI and OSTTI by considering remote back-up protection system failure probability. It is worth noting that both self-checking and monitoring facilities that improve reliability of the protection system are considered in the proposed Markov model. Simulation results demonstrate that variations in reliability indices, ORTTI and OSTTI for power system protection are significant when remote back-up protection system is not fully reliable.

Analysis of solutions for passively activated safety shutdown devices for SFR

In order to enhance the inherent safety of fast reactors, innovative reactivity control systems have been proposed for intrinsic ultimate shut-down instead of conventional scram rods, to cope with the potential consequences of severe unprotected transient accidents, such as an energetic core disruptive accident, as in case of sodium fast reactors.The passive shut-down systems are designed to shut-down system only by inherent passive reactivity feedback mechanism, under unprotected accident conditions, implying failure of reactor protection system. They are conceived to be self-actuated without any signal elaboration, since the actuation of the system is triggered by the effects induced by the transient like material dilatation, in case of overheating of the coolant for instance, according to fast reactor design to meet the safety requirements.This article looks at different special shutdown systems specifically engineered for prevention of severe accidents, to be implemented on fast reactors, with main focus on the investigation of the performance of the self-actuated shutdown systems in sodium fast reactors.

Hypersonic vehicle thermal protection system model optimization and validation with vibration tests

Damage detection for thermal protection systems is crucial for hypersonic flight. Since fastener failure is a critical failure mode for many thermal protection systems, an efficient methodology that does not require a significant amount of experimental data collection and analysis for implementation is desired. In a coming paper, we develop a methodology for localizing fastener failure in a thermal protection system utilizing an experimentally validated finite element model. This paper focuses on validating the finite element model in its healthy state versus low-frequency experimental results obtained on the composite structure for future research in damage quantification. The experimental validation is implemented in three steps to individually account for the unknown composite material properties, insulation effects, and the assembly with the connecting brackets and backing structure. The inverse optimization problem implemented in the first level of experimental validation demonstrated excellent agreement between the finite element model and the experimental results. The overall assembly also demonstrated good agreement between the low-frequency dynamics of the experimental results and the finite element model. The validated finite element-model will then be used to simulate damage in the structure to investigate the effectiveness of vibration mode-based damage detection metrics.

Dynamics of enzymatic and non-enzymatic antioxidants in Japanese plums during storage at safe and lethal temperatures

We investigated the effect of storage temperature as a function of storage time on lipid peroxidation, enzymatic and non-enzymatic antioxidants of Japanese plums (Prunus salicina Lindl.). Commercially mature fruit of ‘Amber Jewel’ cultivar were stored at 0 °C (recommended temperature) and 5 °C (lethal temperature) for 6 weeks. Chilling injury (CI) symptoms in the form of flesh browning and flesh translucency were noticed after 4 weeks of storage at 0 °C and 5 °C, respectively. The lipid peroxidation as reflected by thiobarbituric acid-reactive substances concentration was significantly higher at 5 °C beyond 2 weeks of storage than at 0 °C. The activities of superoxide dismutase, catalase, and peroxidase were significantly higher during storage at 5 °C than at 0 °C. The activities of monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase, increased during the first 2 weeks of storage at 5 °C and helped maintaining ascorbate pool better than at 0 °C. Overall, the response of antioxidative system to chilling stress at 5 °C was comparatively faster and stronger than at 0 °C, but it could not sustain for 6 weeks of storage as the higher levels of oxidative stress associated with fruit ripening at 5 °C might have resulted in failure of the antioxidative protection system.

Preliminary safety analysis of ex-vessel LOCA for the European HCPB TBM system

Ex-vessel loss of coolant accident caused by a double-ended pipe break of the helium coolant system inside port cell is considered as one of the most critical accident for the European Helium Cooled Pebble Beds Test Blanket Module (HCPB TBM) system. The resulting rapid helium blow-down causes an immediate block of the TBM cooling, which requires a prompt plasma shutdown. Even after the plasma shutdown the temperature can increase over the design limit and the accident sequence can lead up to a break of the TBM box protection after the failure of different protection systems. Thus air ingresses in the vacuum vessel from the damaged TBM system and steam from the surrounding ITER blanket and divertor structures. The evaluation of this sequence is very important for the definition of the correct protection strategy of the system. To consider all these different events a methodology has been developed in KIT combining different codes for a complete analysis of the accident. In particular, this paper shows an application of MELCOR code to model beryllium–steam reaction in a particular accidental sequence for the long term cooling.

Power Transformers Condition Assessment of GI Simangkuk Switchyard Sumatra Interconnection in Indonesia

The electricity needs of Indonesia grow an average 10% each year. Therefore, PLN (Perusahaan Listrik Negara) as the only power utility business in Indonesia, has a master plan to develop new power plant, switchyard and transmission system. One of the new developed systems is GI Simangkuk switchyard of Sumatra interconnection system. This switchyard is prepared to improve reliability of Sumatra interconnection system. This site utilizes power transformers of 275 kV. Power transformer is one of the main equipments in power systems. When a failure occurs in a power transformer, the whole system will be failed and the electricity could not be delivered to customer. Each utility has to assure their reliability in order to maintain electrical power system stability by assessing transformer condition. There is an increasing need for better diagnostic and monitoring tools to assess the condition of transformers. Modern power transformers are equipped with software and computer system control. The reliability of this computer systems are needed to evaluate for assurance of system safety. This paper describes the need of assessment and maintenance of power transformers such as outages effect of failures, high cost of maintenance and replacement, increase of world demand, aging effect and used of old transformer, and computer protection system failure. Monitoring and diagnostic methods of transformers assessment have been developing in recently years. They can be separated into traditional and non-traditional methods that have been used in many years and are still in research stage. In this paper we propose a new approach in order to assess power transformer condition by using fault tree analysis.

Power Transformers Condition Assessment of GI Simangkuk Switchyard Sumatra Interconnection in Indonesia

The electricity needs of Indonesia grow an average 10% each year. Therefore, PLN (Perusahaan Listrik Negara) as the only power utility business in Indonesia, has a master plan to develop new power plant, switchyard and transmission system. One of the new developed systems is GI Simangkuk switchyard of Sumatra interconnection system. This switchyard is prepared to improve reliability of Sumatra interconnection system. This site utilizes power transformers of 275 kV. Power transformer is one of the main equipments in power systems. When a failure occurs in a power transformer, the whole system will be failed and the electricity could not be delivered to customer. Each utility has to assure their reliability in order to maintain electrical power system stability by assessing transformer condition. There is an increasing need for better diagnostic and monitoring tools to assess the condition of transformers. Modern power transformers are equipped with software and computer system control. The reliability of this computer systems are needed to evaluate for assurance of system safety. This paper describes the need of assessment and maintenance of power transformers such as outages effect of failures, high cost of maintenance and replacement, increase of world demand, aging effect and used of old transformer, and computer protection system failure. Monitoring and diagnostic methods of transformers assessment have been developing in recently years. They can be separated into traditional and non-traditional methods that have been used in many years and are still in research stage. In this paper we propose a new approach in order to assess power transformer condition by using fault tree analysis.

New Models and Concepts for Power System Reliability Evaluation Including Protection System Failures

This paper develops new models and concepts for incorporating the effect of protection system failures into power system reliability evaluation. The two types of protection failures, i.e., undesired-tripping mode and fail-to-operate mode, and their impact on reliability modeling are discussed. A complete Markov model for current-carrying components is established and its simplified form appropriately describes the overall reliability situation of individual components. Concepts of self-down state and induced-down state are introduced and used to build the composite unit model for quantitatively assessing the influence of protection failures on modeling system states. Finally, a Markov model of power systems with protection failures is proposed for system reliability evaluation. The proposed methodology is then illustrated in detail.

A LIPSKIAN ANALYSIS OF CHILD PROTECTION FAILURES FROM VICTORIA CLIMBIÉ TO ‘BABY P’: A STREET‐LEVEL RE‐EVALUATION OF JOINED‐UP GOVERNANCE1

This paper explores the issue of joined-up governance by considering child protection failures, firstly, the case of Victoria Climbié who was killed by her guardians despite being known as an at risk child by various public agencies. The seeming inability of the child protection system to prevent Victoria Climbié's death resulted in a public inquiry under the chairmanship of Lord Laming. The Laming report of 2003 looked, in part, to the lack of joined-up working between agencies to explain this failure to intervene and made a number of recommendations to improve joined-up governance. Using evidence from detailed testimonies given by key personnel during the Laming Inquiry, the argument of this paper is that we cannot focus exclusively on formal structures or decision-making processes but must also consider the normal, daily and informal routines of professional workers. These very same routines may inadvertently culminate in the sort of systemic failures that lead to child protection tragedies. Analysis of the micro-world inhabited by professional workers would benefit most, it is argued here, from the policy-based concept of street-level bureaucracy developed by Michael Lipsky some 30 years ago. The latter half of the paper considers child protection failures that emerged after the Laming-inspired reforms. In particular, the case of ‘Baby P’ highlights, once again, how the working practices of street-level professionals, rather than a lack of joined-up systems, may possibly complement an analysis of, and help us to explain, failures in the child protection system. A Lipskian analysis generally offers, although there are some caveats, only pessimistic conclusions about the prospects of governing authorities being able to avoid future child protection disasters. These conclusions are not wholeheartedly accepted. There exists a glimmer of optimism because street-level bureaucrats still remain accountable, but not necessarily in terms of top-down relations of authority rather, in terms of interpersonal forms of accountability – accountability to professionals and citizen consumers of services.

Fuzzy Risk Assessment for Life Safety Under Building Fires

Many uncertainties are introduced inevitably during estimating fire risk for life safety in buildings. Probabilistic methods, the most widely used method to deal with uncertainties, require a large number of historical data. Due to the uniqueness of building fires, such data are rarely available. In order to address this limitation, a fuzzy risk assessment method for life safety under building fires is presented. Event tree is constructed to analyze potential fire scenarios arisen from the failure of fire protection systems. According to the definition of fire risk for life safety, occurrence likelihoods and expected casualty numbers of fire scenarios are estimated with consideration of some uncertainties. Due to limited statistical data and poor knowledge about fire dynamic and evacuation, fuzzy numbers are employed to describe these uncertainties. Based on calculated occurrence likelihood and expected casualty number for a fire scenario, the risk of life safety for a fire scenario is obtained as a fuzzy number. A practical case study for a hypothetical one storey commercial building is carried out with the assessment method presented in this paper and compared with the conventional probabilistic assessment results.

New Considerations in Modern Protection System Quantitative Reliability Assessment

Protective relay technologies have evolved from single-function electromechanical and static relays to modern multifunction digital relays over the past few years. Protection systems play a vital role in maintaining a desirable level of reliability in power systems. Thus, their own reliability should be evaluated and any cause of their malfunction should be fully comprehended. In this paper, a new reliability model is proposed that associates protection system failures to four main causes: 1) relay hardware, 2) relay software, 3) ancillary equipment, and 4) human error. In addition, this model can take other aspects of the protection system into consideration, such as human error during tests and repair actions, routine inspections effectiveness, level of reliance on self-checking, local backup misoperation, and stuck breakers. These considerations have a significant impact on the reliability of protection systems and have been neglected in the existing research works. Various capabilities of the model are demonstrated in the case study section.

Simulations of full impact of the Large Hadron Collider beam with a solid graphite target

AbstractThe Large Hadron Collider (LHC) will operate with 7 TeV/c protons with a luminosity of 1034 cm−2 s−1. This requires two beams, each with 2808 bunches. The nominal intensity per bunch is 1.15 × 1011protons and the total energy stored in each beam is 362 MJ. In previous papers, the mechanisms causing equipment damage in case of a failure of the machine protection system was discussed, assuming that the entire beam is deflected onto a copper target. Another failure scenario is the deflection of beam, or part of it, into carbon material. Carbon collimators and beam absorbers are installed in many locations around the LHC close to the beam, since carbon is the material that is most suitable to absorb the beam energy without being damaged. In case of a failure, it is very likely that such absorbers are hit first, for example, when the beam is accidentally deflected. Some type of failures needs to be anticipated, such as accidental firing of injection and extraction kicker magnets leading to a wrong deflection of a few bunches. Protection of LHC equipment relies on the capture of wrongly deflected bunches with beam absorbers that are positioned close to the beam. For maximum robustness, the absorbers jaws are made out of carbon materials. It has been demonstrated experimentally and theoretically that carbon survives the impact of a few bunches expected for such failures. However, beam absorbers are not designed for major failures in the protection system, such as the beam dump kicker deflecting the entire beam by a wrong angle. Since beam absorbers are closest to the beam, it is likely that they are hit first in any case of accidental beam loss. In the present paper we present numerical simulations using carbon as target material in order to estimate the damage caused to carbon absorbers in case of major beam impact.

Modelling the risk of failure in explosion protection installations

This paper proposes a new algorithm to compute the residual risk of failure of an explosion protection system on an industrial process plant. A graph theoretic framework is used to model the process. Both the main reasons of failure are accounted for, viz. hardware failure and inadequate protection even when the protection hardware functions according to specifications. The algorithm is shown to be both intuitive and simple to implement in practice. Its application is demonstrated with a realistic example of a protection system installation on a spray drier.