Conventional Protection Research Articles

A risk-based approach for structural assessment against fire considering escalation and passive fire protection (PFP) optimization

PurposeAccidental loadings such as fire constitute a great majority of potential and actual fatalities in both onshore and offshore installations. In order to prevent human loss and for a safe design of an asset, the risk of fire loading needs to be quantified, in terms of both probability/frequency and consequence aspects. In this paper the authors propose a novel risk-based approach for the assessment against accidental fire loading.Design/methodology/approachIn a conventional passive fire protection (PFP) analysis using ductility level analysis (DLA), fire loads are deterministically applied to a structure whose response is then analyzed. The initial PFP scheme is developed based on the analysis and then optimized. This approach is sometimes misinterpreted as a “risk-based” approach; however, it does not take into account the frequency aspect of the risk assessment. In a risk-based PFP analysis using DLA, fire scenarios are developed in a particular target zone. Then DLA is performed to determine the structural consequence. If personnel safety is of interest, the consequence of the structure is then linked to individual risk (IR) to determine fatalities. The amount of PFP to be applied on the structure is fully based on the risk that is produced by the fire scenarios in target zones.FindingsA new perspective on safe design of onshore/offshore structures for accidental loadings is outlined to estimate the associated risk to potential targets such as personnel as well as asset. The proposed assessment methodology will contribute toward identifying the mitigation measures and safety-critical procedures and equipment and toward a safer design.Originality/valueThis paper presents a new perspective in a safer design of onshore and offshore structures for a fire accidental loading based on risk calculation. Risk is defined as a combination of the frequency and consequence. An event frequency analysis is carried out to determine how often one should expect the event to occur. A consequence analysis is carried out to determine the severity levels of the event. In a risk-based consequence analysis, the severity levels are fully determined based on the risk associated with the event. The proposed novel risk-based assessment methodology against accidental fire loading contributes toward fully understanding the risk from an impact to personnel and to asset perspectives and leads toward safer and optimal design.

Protection Coordination Method Using Symmetrical Components in Loop Distribution System

Power utilities worldwide commonly use the radial distribution system because of its advantages of being simple in structure and having relatively inexpensive installation costs. It has a disadvantage in that its power supply reliability is low because the load side of the fault section will suffer from an outage in the event of a fault in the system. However, recently, with ICT (Information and Communication Technologies) development, system reliability is required to be high as the outage-susceptible loads increase. In addition, the increase in the connection of distributed resources such as renewable energy and electric vehicles is making it impossible to predict the power flow and reducing line utilization. Therefore, a loop power distribution system is proposed as a measure to solve this problem. Because all buses (nodes) in a loop distribution system have two or more power supply routes, they are more reliable than the radial system. It allows them to improve line utilization by connecting lines with different load peak times. However, in the case of a fault in the loop distribution system, the fault current is supplied from both directions, making it impossible to properly isolate the fault section with the protection method of the conventional distribution system. The permissive overreach transfer trip (POTT) method using communication to compensate for the limitations of conventional protection devices, and the other method using directional distance relay, is proposed. However, these methods operate by determining the direction of the fault current but have a disadvantage. It is difficult to detect a fault due to the effects of ground faults and distributed generation (DG) occurring in other lines. Therefore, in this paper, we propose a protection coordination algorithm that uses the negative-sequence component of voltage and current that occur when an unbalanced fault occurs, rather than the determination of the directionality and use of communication. To validate this, we configured a system using PSCAD/EMTDC (Manitoba Hydro International Ltd., Winnipeg, Manitoba, Canada), a system analysis program package and verified the results depending on the type of faults with the proposed algorithm.

Fault Protection Considerations for MVDC Shipboard Power Systems Operating with Pulsed-Power Loads

Medium Voltage Direct Current (MVDC) power distribution architectures are of immense interest for various shipboard power applications due to their advantages over classical MVAC distribution systems with respect to power quality, power density, and efficiency. However, MVDC are far away from maturity when compared to MVAC with respect to fault detection and isolation. Currently, there are no standards available for applying MVDC protection systems in shipboard applications. Furthermore, due to the absence of zero crossings in DC waveforms and unique transient fault signatures, it is challenging to design effective protection system schemes to isolate faults via conventional protection systems. This paper investigates and analyses various types of shipboard MVDC dynamic fault behaviours and signatures under different DC bus disturbances such as: bus to ground, bus to bus to ground, and impact of Pulsed-Power Load (PPL) with and without faults on a shipboard MVDC distribution system. Furthermore, a communication-based fault detection and isolation system controller that improves upon a directional ac overcurrent relay protection system is proposed offering additional protection discrimination between faults and PPLs in MVDC systems. To validate the effectiveness of the proposed protection controller, different bus current disturbances are simulated within a time-domain electromagnetic transient simulation of a shipboard power system including a PPL system operating with different ramp rate profiles, pulse widths, peak powers, and fault locations

Research on the Differential Protection of the SFC Output Transformer for Pumped Storage Hydro Unit

Pumped storage power stations play an great role in promoting new energy consumption, ensuring the safety of power grid, building clean, low-carbon, safe and efficient energy system, and has a broad development prospect. SFC is the most important start-up mode of pumped storage unit, and the output transformer is an important equipment of SFC system, which needs to be equipped with reliable and fast differential protection to ensure its safe and reliable operation. The current frequency varies from 0 to 50Hz during SFC start-up, so the conventional transformer differential protection can not adapt. In this paper, the output transformer differential protection technology is studied according to the electrical characteristics and short circuit fault characteristics of SFC start-up process, the high precision frequency algorithm and the RMS integration algorithm with compensation are proposed to realize the precise measurement of frequency and amplitude, and the ultra-low frequency CT saturation identification technology is proposed to realize the whole process protection of the output transformer from start-up to grid-connection.

New Infeed Correction Methods for Distance Protection in Distribution Systems

The reliability and security of power systems may be jeopardized by the increase in the amounts of renewable generation and the uncertainties produced by these devices. In particular, the protection schemes of traditional power systems have been challenged by the integration of distributed generation (DG) resources. Distance relays (DRs), which have been mainly employed to protect transmission systems, are increasingly proposed as one of the solutions to protect distribution systems with a heavy penetration of DGs. However, conventional distance protection faces several drawbacks that might lead to maloperation. One of those challenges is the “infeed effect”, which causes the impedance seen by the distance relay to be larger than the actual positive-sequence line impedance between the fault and relay location. This paper proposes three new methods to estimate the distance to the fault in the presence of infeeds, whether in a radial distribution feeder or the transmission line. Unlike other solution methodologies in the literature that require communication links to estimate the distance to the fault, the proposed methods only need the local measurement (i.e., the voltage and current measurements at the location of the distance relay) to do the same. The performance of the method is demonstrated with a radial distribution system model in PSCAD™/EMTDC™.

Iot based Fire and Gas monitoring System

In infrastructure and industrial plants the rapid growth is creating environmental issues like pollution, climate change and malfunctioning. It has a great consequence for the requirement of an operationally adaptable, efficient, cheap and smart monitoring systems. For this purpose we come up with idea to use these kind of technology i.e the Internet of Things (IoT) in form of a solution. In this paper, we suggest wireless data gathering frameworks that enable each detector node to track the changes in the behavioural pattern of gases and to identify their role in gas leakage problem, whilst at the same time trying to minimize power consumption. In the proposed device, the temperature detector (DHT 11) the gas detector (MQ2,MQ7 and MQ135) and also humidity sensors are used to determine the environment and the undesirable gas within the manufacturing plant, gauged details can be connected to the web. In addition, our research findings demonstrated substantial energy efficiency and high-precision data analysis relative to conventional protection device strategies. For monitoring the fluctuation of parameters like air pollution levels from their normal levels in this case the sensing devices are connected to the embedded computing system.

AC Microgrids Protection: A Digital Coordinated Adaptive Scheme

A significant challenge for designing a coordinated and effective protection architecture of a microgrid (MG) is the aim of an efficient, reliable, and fast protection scheme for both the grid-connected and islanded modes of operation. To this end, bidirectional power flow, varying short-circuit power, low voltage ride-through (LVRT) capability, and the plug-and-play characteristics of distributed generation units (DGUs), which are key issues in a MG system must be considered; otherwise, a mal-operation of protection devices (PDs) may occur. In this sense, a conventional protection system with a single threshold/setting may not be able to fully protect an MG system. To tackle this challenge, this work presents a comprehensive coordinated adaptive protection scheme for AC MGs that can tune their protection setting according to the system states and the operation mode, and is able to switch the PDs’ setting. In the first step of the proposed adaptive algorithm, an offline setting will be adopted for selective and sensitive fault detection, isolation, and coordination among proposed protective modules. As any change in the system is detected by the proposed algorithm in the online step, a new set of setting for proposed modules will be performed to adapt the settings accordingly. In this way, a new set of settings are adapted to maintain a fast and reliable operation, which covers selective, sensitive, and adaptive requirements. The pickup current (Ip) and time multiple settings (TMS) of directional over-current relays (DOCR), as well as coordinated time delays for the proposed protection scheme for both of the grid-connected and islanded modes of operation, are calculated offline. Then, an online adaptive protection scheme is proposed to detect different fault types in different locations. The simulation results show that the proposed method provides a coordinated reliable solution, which can detect and isolate fault conditions in a fast, selective and coordinated adaptive pattern.

A statistics-based review of microgrid protection with a concentration on adaptive protection

AbstractMicrogrid (MG) is a system of production and distribution of electrical energy that can operate both in grid-connected and islanded modes. This capability leads to significant variations in the fault current level. Moreover, dynamic changes corresponding to the line outage contingencies or outages of the distributed generations (DGs) that are implemented for local generation in the MGs lead to the changes in the fault current level. These changes in the fault current level make some miscoordination between the overcurrent relays (OCRs) in the conventional protection schemes. To overcome this drawback, there is a need for an adaptive protection scheme that can adapt to both operational and dynamic changes and takes effective protection decisions accordingly. This paper first presents a statistic-based review of MG and its protection including total publications, type of publications, the ten most researchers, and the ten most sources. Finally, comprehensive remarks of the 30 most cited papers related to adaptive protection of MG are presented. This paper will help the researchers of the MG protection to learn the most desirable techniques and the concentration of studies in adaptive protection of MGs for future works.

Modified distance protection for transmission line with hexagonal phase-shifting transformer

Phase-shifting transformers (PSTs) provide an economical solution to control the power flow in the electric grids. However, the PSTs vitiate the conventional protection system applied. This paper studies the impact of the delta-hexagonal phase-shifting transformer on the performance of the distance protection relays for the transmission lines. Modified distance protection formulas are derived for both phase and ground faults. The proposed method uses the local measurements at the relay point and does not require voltage or current measurements from a remote substation. Alternatively, the tap position of the phase-shifting transformer is the data needs to be shared between substations which can be accomplished using a simple communication method. The proposed method is evaluated on a simulated transmission line using MATLAB/Simulink packages. The results show the ability of the proposed method to compensate for the PST effect on the distance protection relays.

Nature-Based Engineering: A Review on Reducing Coastal Flood Risk With Mangroves

Integration of mangroves in projects to reduce coastal flood risk is increasingly being recognised as a sustainable and cost-effective alternative. In addition to the construction of conventional hard flood protection infrastructure, mangroves not only contribute to attenuating flood events (functionality), they also recover in, and adapt to, a changing climate (persistence). The implementation of mangroves in flood risk reduction, however, remains complex. This is because the innate functionality and persistence of mangroves depend on a range of environmental conditions. Importantly, mangroves may collapse when environmental impacts or climatic changes exceed key system thresholds, bringing uncertainty into a situation where failure could endanger lives and livelihoods. The uncertainties in mangrove functionality and persistence can be dealt with by (1) improving insights in how ecological and physical processes affect mangrove functionality and persistence across scales, (2) advancing tools to accurately assess and predict mangrove functionality and persistence, and (3) adopting an adaptive management approach combined with appropriate engineering interventions to enhance mangrove functionality and persistence. Here, we review existing evidence, monitoring techniques and modelling approaches from the viewpoint of mangrove functionality and persistence. Inspired by existing guidelines for Nature-based Solutions (NbS) to reduce flood risk, we provide an operationalization for this new approach. In addition, we identify where further research efforts are required for the practical application of mangroves in coastal flood risk management. Key aspects in the variability and uncertainty of the functionality and persistence of mangroves are their failure and recovery mechanisms, which are greatly site- and storm-specific. We propose five characteristic damage regimes that result in increasing reductions of mangrove functionality as well as post-storm recovery periods. Further research on the quantification of these regimes and their thresholds is required for the successful integration of mangroves in coastal flood risk management. Ultimately, the key challenge is the development of adaptive management strategies to optimise long-term mangrove functionality and persistence, or their resilience. Such adaptive strategies should be informed by continued mangrove functionality and persistence assessments, based on continued monitoring and modelling of key mangrove thresholds, and supported through well-established guidelines.

Sediment transport simulation and design optimization of a novel marsh shoreline protection technology using computational fluid dynamics (CFD) modeling

Coastal Louisiana has the nation's most fragile and valuable wetlands, whose loss represents 80% of the total losses in the United States. The severely restricted mobility of conventional shoreline protection structures makes them impossible to be redeployed. The Wave Suppression and Sediment Collection (WSSC) system is a novel technology of high mobility and compatible with existing shoreline protection technologies. Previous laboratory studies on WSSC showed great potential for wave reduction and sediment collection. The current study aimed to optimize the design parameters of WSSC using a validated computational model. A computational fluid dynamics (CFD) model was developed and validated using experimental data from the previous laboratory study. Then, a parametric analysis was conducted with a focus on the performance optimization of wave reduction and sediment collection with respect to pipe diameter and face slope. Simulation results showed that the wave reduction efficiency decreased with increasing pipe diameter and face slope. In contrast, the sediment transport efficiency was enhanced by increasing pipe diameter but was not affected significantly by varying face slopes.

Navigating Nature-Based Coastal Adaptation through Barriers: A Synthesis of Practitioners’ Narrative from Nova Scotia, Canada

Nature based coastal adaptation (NbCA) sustainably helps minimize sea-level rise impacts, using and enhancing the natural capacity of coastal ecosystems. Despite its relative advantages over conventional hard protection infrastructure, the implementation of NbCA is challenged by diverse barriers, many of which cannot be overcome in the absence of appropriate policy directives. This paper draws on organizational practitioners’ case study narratives collected from six NbCA projects planned and/or implemented in Nova Scotia, Canada, to answer how the implementation of NbCA approaches can be navigated through adoption barriers. Results reveal that institutional and psychological barriers dominate, and they also show path-dependency. In addition, barriers are often influenced by the biophysical properties of a restoration site. To navigate through barriers, it is important to identify policy opportunities and redistribute roles and responsibilities. Organizational knowledge creation through partnership and community engagement are two other strategies required for the successful implementation of NbCA.

Effects of fire on the population structure and abundance of Anogeissus leiocarpa and Vitellaria paradoxa in a West African savanna parkland

The West African savanna experiences a prolonged dry season with Harmattan winds which facilitate large and persistent biomass burning from November to April. The fires are mostly caused by humans, mainly in pursuit of the day to day livelihood activities. We examined how fire influences the population structure and abundance of two economically important woody species Vitellaria paradoxa (Shea tree) and Anogeissus leiocarpa (African Birch) in six land use types in the Guinea savanna, Ghana. We calculated the stand basal area, mean densities of juveniles and adult trees, Lorey's mean height of adult trees and Simpson's index of dominance. Eight diameter size classes of each species were analysed by comparing their observed distributions to a three-parameter Weibull distribution across the land use types. A total of 3366 individuals of A. leiocarpa (n = 1,846) and V. paradoxa (n = 1,520) were enumerated. The basal area of A. leiocarpa and V. paradoxa in sacred groves (16.9 m2 ha−1) and unburnt woodlands (20.6 m2 ha−1) was higher than the estimates in the other land use types. High mean densities of A. leiocarpa and V. paradoxa were found in sacred groves (22.7 ± 29.7 stems ha−1) and fallows (15.3 ± 2.2 stems ha−1), respectively. Mean density of juveniles of both A. leiocarpa (248.0 ± 89.1 stems ha−1) and V. paradoxa (68.0 ± 29.7 stems ha−1) were higher in unburnt woodlands than in the other land use types. A. leiocarpa was absent in fallows and burnt crop fields. An inverse J-shaped distribution was found in sacred groves for both species.The absence of A. leiocarpa in burnt crop fields and the decrease of some size classes of V. paradoxa in both burnt and unburnt crop fields indicate the need for sustainable conservation of both species. Furthermore, the inverse J-shape distribution found in sacred groves for both A. leiocarpa and V. paradoxa implies that these species thrive best with minimal anthropogenic disturbances. Although species conservation is achieved through conventional protection, traditional or cultural conservation practices which avoid the indiscriminate use of fire should be highly promoted to ensure sustainable conservation of species.

A similarity-based framework for incipient fault detection in underground power cables

Incipient faults are known as the faults mainly occurring on the junctions of underground power cables. Clearing quickly, these faults are difficult to detect by conventional protection equipment, leading to insulation degradation and permanent fault in the power cable over time. In this paper, employing similarity functions, a new method is put forward to distinguish the existing fault from other similar events with both high speed and accuracy. The proposed algorithm consists of a two-stages algorithm including change detection, disturbance identification, and fault detection. The proposed method performs the calculation on the voltage signal that is recorded at the sending end of the line. The cross-correlation function is employed for identifying change detection and determining disturbance time. Afterward, using sinusoidal curve fitting, the algorithm can distinguish the incipient fault from sudden load change, capacitor switching, and harmonic load. The accuracy of the proposed approach is verified by some experimental data and 6272 simulation data obtained from four types of well-known arc models, capacitor switching, and also load variations.

Rancang Bangun Adjustable Power Supply dengan Overload Current Protection Berbasis IC LM723

The type of power supply that is commonly used is the adjustable power supply. Its ability to generate a varying voltage level, making it suitable for testing a wide variety of electronic circuits. A conventional protection system of this type is usually a fuse, overcurrent event occurred due to improper installation of the components and circuit design will make this protection system is active and needed replacement fuse. To eliminate the need for fuse purchases at the Instrumentation and Electronics Engineering Laboratory, Undip Vocational School, an adjustable power supply was built with an overload current protection based on the LM723 IC for an operating level of 1 ampere. The system was built as non-fuse protection current limiter. This study will describe the stages of the manufacturing and testing system. The test results show that the power supply output is linear with the coefficient of determination = 0.99 and correlation = 0.99. The system can also limit the average maximum working current of 0.95 for several variations of load resistance.

Modelling and Simulation of SCADA and PLC System for Power System Protection Laboratory

Abstract The protection of power system is an essential trait in a huge network to efficiently detect and isolate the sections undergoing faults or abnormal behaviour. The key components of a protection scheme include circuit breakers, relays, switchgears and fuses which employ communication from one station to another to achieve high-speed tripping. The automation of these components at the laboratory level using programmable logic controller (PLC) along with supervisory control and data acquisition (SCADA) system owns paramount importance for intelligent decision making, sensing, actuating, monitoring and maintaining the record in the host server. This paper discusses such a technique for conventional power system protection laboratory at a new level of development to promote a control system through PLC and SCADA. The control system has indication of over and under values of voltage, load and frequency, which can trigger malfunctioning of equipment and must be rectified. Furthermore, ground fault and inverse current indication are added to the system for monitoring and controlling purposes. The proposed system enhances the efficiency and safety of the expensive equipment and the personnel to the next level and also introduces new standards of automated protection schemes for modern technical institutes.

Managing piracy: Dual-channel strategy for digital contents

<p style='text-indent:20px;'>The Internet offers digital content disc producers the opportunities to design dual channels by introducing an online-direct store alongside traditional retail stores, but also leads related firms to suffer significant piracy problems. Using a game-theoretic framework, we explore dual-channel marketing optimality as a piracy-mitigating strategy for digital content sold in the physical disc format. We construct a price-setting game between a digital content producer and its independent retailer(s) in a pirated market by endogenizing the producer's copyright protection investments. We show that dual-channel marketing, a complement or a substitute for conventional copyright protection, can strategically mitigate the piracy level by increasing the equal-size retail sales volume. We also investigate how firms' pricing strategies and profits are influenced by the endogenous interaction of dual-channel marketing and copyright protection. We unexpectedly find that in a pirated market with insufficient copyright protection, dual-channel marketing can simultaneously raise firm pricing and sales volumes when the producer sells through a monopolistic retailer. We also identify the conditions under which dual-channel marketing can mitigate profit losses caused by piracy for the producer and the retailer(s). Unlike previous research which shows that dual-channel marketing benefits the producer and the monopolistic retailer because it mitigates double marginalization, in the pirated market, this win-win outcome occurs even if accompanied by aggravated double marginalization. Moreover, dual-channel marketing can mitigate all the firms' profit losses caused by piracy only when it can complement conventional copyright protection, i.e., when the producer sells through a monopolistic retailer or duopolistic retailers. In each situation, counter-intuitively, as copyright protection becomes increasingly costly, although the retailer(s) is (are) more willing to accept dual-channel marketing, the producer has a decreased incentive to design such sales channels.</p>

Coordination of non‐directional overcurrent relays and fuses in active distribution networks considering reverse short‐circuit currents of DGs

Abstract The main protection equipment in radial distribution networks are non-directional overcurrent relays (NDOCR) and fuses which are coordinated using the conventional protection coordination method. By installing distributed generations (DGs) in the network, reverse short-circuit currents (SCC), injected from DGs, can lead to false tripping of NDOCRs and false melting of fuses. In the previous studies, some methods have been proposed to overcome these issues using directional overcurrent relays, fault current limiter, and adaptive methods that relay on communication. The present paper proposes a new coordination method to prevent these issues without the need for installing a new equipment, by proposing a new set of selectivity constraints. Here, selectivity between equipment is established, and false tripping and false melting issues are mitigated. The coordination of protection equipment according to the proposed method requires the use of optimization algorithms, and therefore, the proposed method is formulated as a mixed-integer linear programming method to take advantage of mathematical optimization algorithms. The proposed coordination method is applied to a real distribution network and the results indicate the high efficiency of the proposed method in dealing with false relay tripping and fuse melting issues.

Protecting Distribution Systems With Inverter-Interfaced PV Plants Using Q-Axis Components

Satisfying fault ride-through requirements, solar photovoltaic (PV) plant remains connected to the grid even during a fault. With current limiting feature, the plant current during a fault becomes comparable to its rated current. This imposes challenges to conventional local data-based protection methods employed in the relay on PV-side. In such a situation, the selectivity of a protection scheme is crucial for maintaining an uninterrupted supply to customers. In this article, a q-axis component-based protection scheme is proposed for the distribution system with a PV plant. The method extracts the second-order harmonic components of q-axis voltage and current at relaying point for fault detection and direction identification. Using this direction information at both ends of a line segment to be protected, internal and external faults are discriminated. The performance of the proposed method is tested on 14-bus distribution system for various fault cases. A comparative analysis with existing techniques shows the strength of the proposed method. Hardware-in-loop testing using OPAL-RT simulator as system and Arduino NANO microcontroller as relay validates the performance of the proposed method in real-time.

A wavelet-based restricted earth-fault power transformer differential protection

This paper proposes a restricted earth fault protection based on the wavelet transform (REFW) for detecting ground faults close to the transformer neutral point (turn-to-ground faults) and supporting the conventional phase differential protection, which presents limitations in this kind of faults. The proposed REFW protection uses only high-frequency components instead of phasor estimation, speeding up the detection of turn-to-ground faults. A performance comparison between the proposed wavelet-based restricted earth-fault differential protection and the respective conventional restricted earth-fault (REF) unit was accomplished considering simulated turn-to-ground faults, involving a few winding turns. The proposed method is more efficient and faster than the conventional one, reaching a success rate of 100%.