Failure Of Protection System Research Articles

The impact of high‐voltage circuit breaker condition on power system reliability indices

AbstractCondition monitoring data can be used to assess the health of a power system component but is rarely used to assess the reliability of the power system they are part of. For high‐voltage circuit breakers (HVCBs), the susceptibility to various failures can be assessed by examining trip coil current (TCC) measurements. HVCBs have two failure modes, failure to trip on command and tripping without a command, which are triggered by various failure mechanisms that in turn may depend on the technical condition of the HVCBs. The aim of this article is to demonstrate a methodology for quantifying the impact that the technical condition of HVCBs has on the power system reliability indices. An equivalent transmission line failure rate considering protection system failures, including failures related to HVCBs, can be calculated by computing contributions from various fault types (FTs). This article proposes a framework that can quantify the frequency of the FTs that are affected by HVCB condition. The system‐level effects are then evaluated using approximate methods for power system reliability evaluation. To demonstrate the principles and benefits of this methodology, a case study is presented that incorporates HVCB condition data from the Icelandic transmission grid into an illustrative 4‐bus test system; a dataset of 83 TCC measurements from 38 HVCBs from the Icelandic Transmission System Operator is used, together with an outage database of life histories of 464 HVCBs from the Icelandic transmission grid. Results indicate that the condition deterioration associated with the probability of an HVCB failing to trip on command can significantly degrade the reliability indices.

Inverse-time protection method of pumped-storage unit vibration

Vibration protection is a reliable mean for safe operation of rotating machinery. In recent years, vibration protection of pumped storage unit gets more and more complicated, resulting in an increasing risk of vibration protection system failure. Focusing on vibration characteristics of pumped-storage units, the inverse-time vibration protection method for of pumped-storage unit vibration was proposed based on material fatigue damage curve and linear damage accumulation theory. Difficulties of determining damage level were provided on applying damage accumulation method to vibration protection. Simplified inverse-time protection method for vibration of pumped-storage unit was proposed, and research showed that the inverse-time vibration protection threshold should be set according to vibration accumulation that avoids all unit transient processes, the reliability coefficient can be determined from 1.5 to 2.0, the refresh periods of unit vibration characteristic values do not affect the cumulative calculation results, and the inverse-time vibration protection has characteristic of self-returning. The vibration protection method based on inverse-time has the advantages of reliable principle, simple logic, and easy implementation. It has the characteristics of reliability, selectivity, sensitivity, and rapidity as relay protection in electric engineering. It solves the problem of dual parameter coordination in the traditional protection strategy with fixed threshold and fixed time delay. The method can be extended to the vibration protection of other types of rotating machinery.

Failure Analyses on a Flexible Anode Cathodic Protection System in a Station.

Flexible anodes are a common form of anode ground bed for the cathodic protection of buried pipes in station areas, especially in new stations. In most cases, flexible anode ground beds could obtain uniform potential distribution and good protection. However, in the process of operation, there are also failure conditions such as anode body or cable breakage, electronic shorting between anode and pipes and other situations, resulting in poor protection. How to troubleshoot failures has become a difficult problem restricting the application of flexible anodes in actual production. In this paper, the failures of a flexible anode cathodic protection system in a station were assessed and analyzed in detail. The main reasons for the failures were the electronic shorting between the flexible anode and buried pipe in local area and the breaking of a partial flexible anode. The troubleshooting methods for two kinds of failures were explored. By measuring the potentials of both the flexible anode and pipes in different areas and the excavation test, the location of electronic shoring was determined. And through measuring the grounding resistance of the flexible anode and excavation test, the breaking location of the flexible anode was found. By repairing the failure sites, the failed system was restored to normal, which could provide guidance for the failure analyses of the flexible anode cathodic protection system.

Information Fusion Approach for Transformer Protection: Concept, Application, and Field Data Verification

The ultimate goal of power transformer protection system is to quickly and reliably detect internal faults while remaining stable for external faults and transients. Since in the conventional protection system, each relay decides about the transformer condition independently, it can be considered that the output signals of relays are logically "OR"ed with each other. In this case, confirming internal fault condition by more than one relay does not increase the confidence level of decision-making and consequently the operation speed, while maloperation of one function causes the failure of overall protection system. To cover this drawback, this paper introduces a new protection paradigm based on fusing the decision of independent protection functions. The fundamental concepts along with an application of this approach are proposed in the paper. Besides, to improve the fusion performance, a probabilistic approach for the protection functions is suggested. Results of the comprehensive evaluations and field data verifications demonstrate that the proposed approach not only increases the operation speed and dependability of protection system, but also improves its security by accurately detecting the transformer status even in cases where a protection function maloperates for a transient condition.

An entropy-based scheme for protection of DC microgrids

The design of an appropriate scheme for protection of DC microgrids is still a significant challenge. This paper proposes a new method for protection of DC microgrids when subjected to various types of faults and modes of operation. The proposed method shares some features of the differential protection scheme and adopts the Shannon entropy to evaluate the "informational value" of current waveforms in the presence and absence of a fault. It uses the relative entropy of the current waveforms at the two sides of the faulty line to detect and characterize a fault. In the case of failure in the primary protection system, the entropy variations of the current waveforms are used to detect the faulty line. The main features of the proposed method include a) accuracy in a noisy environment with poor data synchronization (due to the delay in communication links) and varying network topology, b) fast operation regardless of the fault type and location, c) ability to detect high-impedance faults, and d) provision of backup protection. The efficiency of the proposed method is demonstrated by comparing the simulation results of several case studies in a typical ring DC network with those obtained using an advanced differential protection scheme.

Impact of cyber failures on operation and adequacy of Multi-Microgrid distribution systems

The primary objective of this paper is to create a suitable reliability assessment framework for Cyber–Physical Multi-MicroGrid (CPMMG) distribution systems, considering the device-level failures of control and protection systems. For this purpose, the typical structure of a CPMMG distribution system with a centralized protection system is first exemplified. Then, the interdependencies between cyber and power infrastructures are investigated in such systems. Regarding the protection system, a Markov model is presented to investigate hidden failures of fault location, isolation, and service restoration processes. Possible operation modes in a CPMMG distribution system – normal, islanding, joint, and shutdown modes – are then explained and modeled. Finally, a suitable Monte Carlo simulation-based reliability assessment framework is developed to quantify well-known reliability indices. In addition, two new adequacy indices are proposed: Interrupted but Gained Compensation (IbGC) and Supplied by Expensive Resources (SbER). A comprehensive case study is conducted to reveal the salient features of the proposed framework. The result showed that the impact of cyber failures in such systems is highly dependent on the design of the cyber system. Therefore, the adverse impact of cyber failures of control and protection systems can be effectively mitigated by proper design.

Electrical Conductivity of Pipeline Deposits Under Pressure and Their Impacts on Sales-Gas Pipeline Cathodic Protection Systems

Summary Natural gas pipelines are critical for safe and efficient energy transport across large distances. To maintain operational safety, pipelines use cathodic protection systems that minimize the rate of external corrosion. This work characterizes the effects of black powder deposits, a widely experienced operational hazard across the natural gas industry, on the failure of pipeline cathodic protection systems due to electrical “shorting” of isolation devices. Black powder sludgy deposits from coal seam gas (CSG) pipelines were analyzed, revealing electrical conductivity values within the range of 580 to 5400 µS/cm when under pipeline pressure. These values were used to calculate the internal resistances of monolithic isolation joints (MIJs), a type of electrical isolation device, to show that electrical shorting (internal resistance of < 100 Ω) can occur for black powder sludgy deposit thicknesses in the range of millimeters. To reduce the frequency of such shorting events, it is recommended that upstream dehydration systems be designed to reduce carry-over of triethylene glycol (TEG), that internal nonconductive coatings be applied to isolation devices, and that these devices are installed in ways that facilitate regular cleaning.

Nanoindentation deformation and fracture mechanisms of SiC/SiO2 thermally oxidized in plasma wind tunnel

Mechanical strain and delamination of surface oxide from substrate are important mechanisms leading to failure of thermal protection systems in hypersonic vehicles. In this work, the deformation and fracture mechanisms of a thermally oxidized SiC/SiO2, formed by dynamic oxidations inside a plasma wind tunnel, are studied by nanoindentation experiments and finite element modeling. The results show an amorphous and uniform SiO2 formation on β-SiC at 1200∼1400 °C in the plasma flow (pressure ≈6.5 kPa), after long-term single/repeated oxidations. In the plasma environment the passive oxidation of SiC is slow, as a result the as-formed SiO2 is very thin. The SiO2 thickness is only ≈680 nm after 8 × 500 s dynamic oxidation. SiC/SiO2 exhibits a strong depth dependent indentation behavior, and at a critical indentation depth, delamination of SiO2 oxide scale is triggered. Finite element modeling helps decouple the effects of SiC substrate, residual thermal stress and interfacial delamination on the nanoindentation response of SiC/SiO2. The results evidence that delamination has a negligible effect on the nanoindentation response, and the main contributions are the SiC substrate and residual thermal stress. This work may forward the fundamental understanding of deformation and fracture mechanisms of oxide scales on thermal protection materials in response to localized loading conditions.

ANALISIS PENGUJIAN TAN DELTA PADA TRANSFORMATOR ARUS DI GITET TASIKMALAYA BAY PENGHANTAR BANDUNG SELATAN-1

Current transformers are essential for substation protection. It converts large currents into smaller currents that are used for measurement and triggering protection systems. Errors in the conversion of electric current can lead to measurement inaccuracies and protection system failures. Improper maintenance and use can shorten the life of the transformer and also lead to earlier system failure. One of the tests applied is the tan delta test to determine the loss coefficient of the insulating material. A decrease in insulation quality increases the tan delta value. The capacitance value is also measured in the tan delta test. An increased capacitance value indicates the paper insulation has been damaged. Generally, damaged insulation causes a short circuit between capacitor layers which is characterized by an increase in capacitance value. By using the GST-Ground method with the Megger Delta 4110 measuring instrument, the tan delta results of the R, S, and T phases in the southern send bay of Bandung-1 GITET Tasikmalaya are 0.42%, 0.47%, and 0.45%. The results of independent calculations are phase R, S, T are 0.29%, 0.28% and 0.31%. From both results, the current transformer can be said to be feasible to operate because the tan delta value is below 1% which is the operational standard of the current transformer.

Dangers and risks of personal data loss

The success of a company depends in many ways on its attitude to the personal data being handled. A failure in the personal data protection system can lead to irreparable consequences. The article describes the main dangers and risks of personal data loss, both for individuals and for companies, and provides recommendations for employees dealing with clients’ personal data.

Identification and assessment of occupational safety risks in case of failure to capture an orphan source of ionizing radiation

Occupational safety and health belong to fundamental human rights. This fully applies to the protection of employees and other persons, which operate or are located in facilities for the collection of scrap metal. The founder of the landfill or the employer has an irreplaceable place in the field of protection of persons against the effects of ionizing radiation. Based on the identification and assessment of occupational safety risks in the event of failure to ensure timely detection of an orphan source of ionizing radiation, the operator must assess all risk factors with emphasis on radiation. At the same time, it must take specific regime measures, which would minimize the impact on people and the environment. The article deals with the causes of failure the system of protection against the effects of ionizing radiation. The assessment of these causes is performed using the fault tree analysis method with the application of Boolean equations. The result of solving the problem is the calculation of the failure of the regime protection system in the devices, intended for the collection of scrap metal, caused by human error as a result of intentional or negligent actions of the operator and insufficient training in the areas of control of measuring devices, principles of correct use of detection devices, insufficient visual identification of potentially dangerous objects. The contribution of this paper is in the design of appropriate regime measures eliminating the consequences of non-capturing a source of ionizing radiation.

The Implementation of Diverse Actuation System in ACPR1000 Nuclear Power Plants

In order to improve the capability of dealing with software common cause failure (CCF) of digital reactor protection and monitoring system (RPMS), the diverse actuation system (DAS) is introduced for ACPR1000 nuclear power plants. From economic and feasibility point of view, the solution of DAS sharing with RPMS sensors and actuators is suggested; after capturing the function requirement of DAS, the automatic functions and manual functions assigned to it are determined based on transient analysis of design basic accidents concurrent with software CCF of RPMS. The independent verification proves that the reactor can be fallen back to and maintained at safety shutdown state, thanks to these DAS functions. Insight into probabilistic safety assessment proves significant reductions of risks are contributed. The critical technical issues while implementing DAS, such as measures to ensure its diversity from RPMS, precautions for preventing from its spurious actuation, isolation and independency from RPMS, and its testability and maintainability, are deliberately settled to improve its engineering reliability and alleviate the impact on RPMS as far as possible. Field programmable gate array technology that is diversified from RPMS is chosen to build DAS of ACPR1000 nuclear power plant, and the commissioning test verifies that it is capable of performing its designed functions. At last, a set of DAS-specific, paper-based, and event-oriented emergency operating procedure is developed, verified, and validated. Until now, the DAS system has always been successfully operating in all ACPR1000 nuclear power plants for several years.

The Covid-19 outbreak, a Failure of Social Protection System: A Policy Perspective of Energy and Economic Recovery

COVID-19 has proliferated personage suffering around the world. The virus is contagious medically and economically as well. The study's main aim is to examine the failure of the social protection system caused by the COVID-19 pandemic. Three major dimensions of the social protection system have been addressed in this research—a shock to the labor market, health emergency, and massive change in energy usage. Covid pandemic had cost the world economy more than $2 trillion. The labor market is badly affected significantly; workers engaged in the informal economy. The Director-General (WHO) has declared the COVID-19 pandemic as a public health emergency of international concern. It is one of the highest levels of alarm by WHO in history. Global Energy Review 2020 shows that those complete lockdowns have a 25% decline in the energy demand per week. As economic activity slowdown due to the closure of the industry, banned transportation, and lockdown. Conclusively, it is examined that the coronavirus pandemic has brought a worldwide failure of social protection system required a comprehensive policy and a firmed leadership to stand against the outbreak.

Reliability Modeling and Analysis of Reactor Protect System Based on Petri Net

Digital control is an inevitable trend in the development of nuclear power. The application of digital control systems in nuclear power plants not only improves the control capability of nuclear power plants, but also increases the complexity of the system. Traditional reliability analysis methods (such as event trees and fault trees) can only perform static analysis on the reactor protection system, but cannot reflect the impact of maintenance activities on system reliability. In the dynamic analysis method, the Markov model is usually applied to the exponential distribution, and the failure and maintenance process of the reactor protection system does not all obey the exponential distribution. In this paper, the Petri net method is used to model the reactor protection system, and the modules are modeled separately according to the function of the system, and finally the model is integrated. Modularization improves the flexibility and understandability of the model, shortens modeling time, and improves robustness. The proposed model was simulated using the GPenSIM tool, and the state reachability diagram of the system with or without maintenance process was obtained, and the probability of shutdown and refusal was obtained.

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

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.

TRACE Analysis of a Loss of Alternating-Current Power Without Rod Insertion for the NuScale Power Module—I: Basic Event Progression and Long-Term Behavior

The U.S. Nuclear Regulatory Commission (NRC) staff often performs confirmatory analysis to support regulatory decision making. In the current work the TRAC/RELAP Advanced Computational Engine (TRACE) code was used to study the transient system response for the NuScale power module to a beyond-design-basis event where the control rods fail to insert. The regulatory purpose of the current work was to confirm the results of analyses provided by the applicant as part of their probabilistic risk assessment analysis that demonstrates that the core is not damaged under certain conditions when the control rods fail to insert. The NRC staff performed calculations using a TRACE model of the NuScale power module that includes both the primary and secondary systems that simulates a loss of alternating-current power and complete failure of the module protection system to insert control rods. The NRC staff analyses demonstrate that under these conditions the reactor stabilizes at a new stable condition with minor power and pressure oscillations where core power is balanced by passive heat removal.

Impact of Microgrid Operation on the Performance of Overcurrent Relay Coordination and Assessment of Differential Relay Coordination

Penetration of distributed generations (DGs) enable microgrid to operate in different mode such as grid-connected and islanded mode with radial and mesh topology. The fault current magnitude and direction varies according to the operating conditions which imposes serious protection challenges and may lead to protection system failure and nonselective relay operation. Thus, the impact of operating conditions on the existing overcurrent relay coordination has been extensively studied in this paper. The overcurrent relay coordination is implemented using genetic algorithm (GA) considering different topology and operating modes of the microgrid. Extensive test results indicate that the existing overcurrent relay coordination may fail during some critical operating conditions and thus, a differential relay coordination scheme is proposed which provides improved performance for microgrid operating in different modes and different network topologies with both synchronous and inverter-based DGs.

A graph-based modelling framework for vulnerability analysis of critical sequences of events in power systems

Major blackouts may have critical societal consequences and are very challenging to analyse and mitigate. Part of the challenge lies in the complex sequences of events that characterize such blackouts and that involve a diverse set of mechanisms propagating the events. The analysis is also challenged by the great uncertainties associated with individual mechanisms and thus with the overall likelihood of sequences of event. This article proposes a general framework which uses a graph to describe the causal relationship between consequences, system states, initiating events and barriers. A concrete implementation of the framework is presented by implementing exemplary models for three transition mechanisms, namely i) protection system failures, ii) failure of corrective actions, and iii) failure of islanding. In the implementation, a graph is automatically generated where edges are associated with these transition mechanisms. A vulnerability analysis methodology based on the modelling framework is proposed that allows for identifying how critical consequences might occur as well as estimating their likelihoods of occurring. The vulnerability analysis methodology moreover incorporates a possibilistic uncertainty analysis to explicitly capture uncertainties associated with the likelihood of events. Finally, a case study considering a small but realistic test system is used to illustrate the approach and demonstrate its main advantages: i) The vulnerability analysis can identify critical sequences of events and barriers to mitigate them, ii) the graph-based representation allows for exploring the sequences of events and understanding the vulnerabilities, iii) the modelling framework is general and can incorporate multiple transition mechanisms, and iv) the analysis accounts for the large uncertainty associated with the critical sequences of events.

Fast failures in the LHC and the future high luminosity LHC

An energy of $362\:\text{MJ}$ is stored in each of the two LHC proton beams for nominal beam parameters. This will be further increased to about $700\:\text{MJ}$ in the future High Luminosity LHC (HL-LHC) and uncontrolled beam losses represent a significant hazard for the integrity and safe operation of the machine. In this paper, a number of failure mechanisms that can lead to a fast increase of beam losses are analyzed. Most critical are failures in the magnet protection system, namely the quench heaters and a novel protection system called Coupling-Loss Induced Quench (CLIQ). An important outcome is that magnet protection has to be evaluated for its impact on the beam and designed accordingly. In particular, CLIQ, which is to protect the new HL-LHC triplet magnets, constitutes the fastest known failure in the LHC if triggered spuriously. A schematic change of CLIQ to mitigate the hazard is presented. A loss of the Beam-Beam Kick due to the extraction of one beam is another source of beam losses with a fast onset. A significantly stronger impact is expected in the upcoming LHC Run III and HL-LHC as compared to the current LHC, mainly due to the increased bunch intensity. Its criticality and mitigation methods are discussed. It is shown that symmetric quenches in the superconducting magnets for the final focusing triplet can have a significant impact on the beam on short timescales. The impact on the beam due to failures of the Beam-Beam Compensating Wires as well as coherent excitations by the transverse beam damper are also discussed.

Preventing cascading failure of electric power protection systems in nuclear power plant

Cascading failure is the main cause of large blackouts in electrical power systems; this paper analyzes a cascading failure in Hanbit nuclear power plant unit two (2) caused by a circuit breaker (CB) operation failure. This malfunction has been expanded to the loss of offsite power (LOOP). In this study, current practices are reviewed and then the methodologies of how to prevent cascading failures in protection power systems are introduced. An overview on the implementation of IEC61850 GOOSE messaging-based zone selective interlocking (ZSI) scheme as key solution is proposed. In consideration of ZSI blocking time, all influencing factors such as circuit breaker opening time, relay I/O response time and messages travelling time in the communication network should be taken into account. The purpose of this paper is to elaborate on the effect of cascading failure in NPP electrical power protection system and propose preventive actions for this failures. Finally, the expected advantages and challenges are elaborated.