Overcurrent Protective Devices Research Articles

Protection System of the Electric Power Distribution System of Notre Dame of Marbel University, Koronadal City, South Cotabato

A vital instrument for evaluating the effectiveness and safety of electrical systems is the power system analysis. Protecting people and equipment from errors is part of this. These assessments examine the load, the equipment, and the foreseeable needs. A lack of short-circuit current protection can harm equipment and endanger workers. The main goal of this study is to assess if the various protection devices utilized in the Notre Dame of Marbel University’s Main Campus electrical system comply with the established standards. Through a real survey (opening panel boxes and reviewing the original Electrical Plan), the researcher will ascertain the various protection devices in operation. Two approaches are used to test for short circuits: the MVA method and the per-unit method. When determining fault current, only the three-phase fault is considered in the calculation since it is the one having the largest fault value. Aside from the mentioned, the transformer rating calculations were also done. The resulting data will then be compared to the actual protective devices installed in the building. Short circuit currents must be less than the Kilo Ampere Interrupting Capacity rating of the installed protective devices. In conclusion, after conducting a thorough analysis of the current loading schedule and comparing the results obtained through the MVA and per-unit methods, it is evident that the various installed Overcurrent Protective Devices are operating safely. The calculations revealed a substantial disparity of 35.57% between the two methods. Furthermore, the t-test conducted on paired data confirmed the statistical significance of the differences between these two approaches. With this, the researcher recommends conducting a separate study to verify branch circuit calculations, implementing primary metering, and prioritizing the rehabilitation of the Pantua and Alunan lines to enhance the safety and reliability of the electrical system, particularly in tracing complex branch circuits. Keywords: power system analysis, MVA method, per unit method, comparative analysis, Notre Dame of Marbel University

Experimental Study of the Pressure Exerted in the Body of a High-Voltage Fuse and Metal Enclosed Switchgear

This article presents the importance of analyzing the breakdown behaviour of high voltage fuses and highlights the pressure values at the fuse ends. The theoretical basis, test scheme structure, design and sizing elements of fuse components, and numerical simulations performed in Matlab/Simulink are presented. The extinguishing environment is not modelled as it is considered to be a vacuum Starting with the oldest overcurrent protection device and continuing with the importance of high voltage fuses for operational safety, the study presents the behaviour of high voltage fuses during short-circuit current interruption. The key element is the value of the pressure on the contacts of fuses, which is often ignored in favour of the pressure of the middle element. When fuses change from solid to liquid state the inner parts are hotter than the outer parts and melt first, and the melting zone extends to the periphery. The study found that the pressure is much higher and is an important value for designers. Experiments showed that the maximum pressure is reached during the arcing period, a significant finding for the design process of the contacts of a high-voltage fuse. The research was then extrapolated to check the pressure in metal enclosed switchgear containing fuse combinations.

Reinforcement effects of graphite fluoride on breakdown voltage rating and Pyro-Resistive properties of carbon Black/Poly (vinylidene fluoride) composites

The utilization of conductive polymer-matrix composites (CPCs) with a high concentration of filler as an overcurrent protection device can reduce operational load and improves circuit stability. However, limitations such as reduced positive temperature coefficient (PTC) intensity and inferior voltage breakdown strength hinder its development. To overcome this, the study investigates the integration of graphite fluoride into carbon black (CB)/Poly (vinylidene fluoride) (PVDF) composites. The graphite fluoride-doped CPCs demonstrate outstanding voltage resistance, PTC intensity, and electrical properties, which can be ascribed to the heightened compatibility and adhesion between CB and PVDF, resulting in diminished migration and agglomeration of conductive fillers during current shock and thermal conditions. Graphite fluoride also acts as a shield, counteracting the negative effects of electrical, chemical, and thermal breakdown failures, thus inhibiting PVDF degradation during current impact. Overall, this approach significantly enhances the voltage withstand capability of overcurrent protection devices under current saturation conditions.

Extending the Life of Low Voltage Adjustable Speed Drives: The Newest Technology to Eliminate Risk

A fundamental aspect of low voltage adjustable speed drives’ (LV ASDs’) overcurrent protection is the elimination of harmful input power anomalies that could significantly damage the sensitive electronics in and around the ASD. This article provides an overview of the newest LV solid-state circuit breaker (SSCB) technology and how petroleum and chemical industry users can take advantage of its ability in eliminating almost all the electromechanical stresses applied at the input to any LV ASD when protected with traditional circuit breakers or high-speed protective fuses. This higher level of protection comes through the use of SSCB technologies that provide the lowest let-through energy level of any overcurrent protective device available today. At the same time, these devices eliminate risk by reducing harmful arc flash incident energy to near-negligible levels while requiring no maintenance.

Research on the identification of high-resistance ground faults in the flexible DC distribution network based on VMD–inception–CNN

With the rapid development of flexible DC distribution networks, fault detection and identification have also attracted people’s attention. High-resistance grounding fault poses a great challenge to the distribution network. The fault current is very small and random, which makes its detection and identification difficult. The traditional overcurrent protection device cannot identify and act on the fault current. Therefore, this paper proposes a fault detection method based on variational mode decomposition (VMD) combined with the convolutional neural network (CNN) of the inception module. This method first uses VMD to decompose the positive transient voltage. Second, it inputs the decomposed signal into CNN for training to obtain the optimal parameters of the model. Finally, the model performance is tested based on the PSCAD/EMTDC simulation platform. Experiments show that the detection method is accurate and effective. It can realize the accurate identification of seven different fault types.

A Current Selective Tripping Protection Scheme for the Distribution Network with PV

At present, the global energy demand keeps rising due to population growth. Therefore, large numbers of photovoltaics (PV) are being integrated with power systems. Solar PV’s installed power capacity is poised to surpass that of coal by 2027, becoming the largest in the world. The integration of PV has changed the direction of the power flow. Under these circumstances, the changed magnitudes and directions of fault current may result in maloperations and non-operations of conventional relays. In this work, a simple and reliable current selective tripping protection scheme is proposed, which is based on the direct communication between overcurrent protective devices on both sides of the line. Through logical programming of the operation information of each protection, the fault location is detected, and the instantaneous trip is realized. The simulation analysis of PSCAD/EMTDC shows that the protection scheme can reliably detect and isolate faults happening at the feeder and bus under different fault conditions; besides, it has good performance in detecting certain resistance grounding faults. The proposed protection scheme can effectively solve the problems caused by PV systems penetration and improve system safety.

Solar Photovoltaic System Performance Improvement Using a New Fault Identification Technique

Identifying faults in the photovoltaic (PV) arrays is very much essential in improving the PV system’s safety and reliability. Solar PV arrays operate with non-linear characteristics, installed with maximum power point trackers (MPPT’s), and blocking diodes cause mismatch levels. Line-to-line and line-to-ground faults are identified, and the faulted circuits are isolated by means of over current protection devices (OCPD) and ground fault protection devices (GFPD). In order to improve the accuracy of fault detection, artificial intelligence (AI)-based techniques like Fuzzy inference, wavelet, support vector machine, and k-nearest neighbors are used. The drawback of AI-based techniques are (1) requirement of large dataset for effective fault identification and also show incompatibility if there is low irradiation and (2) require a larger number of voltage and current sensors. An experimental setup of 160 W, 4 × 4 solar PV array having PV modules (SPB) is subjected to different fault conditions (CS), and the faults are identified using the minimum number of sensors. The faults that are not detected by the conventional methods are detected using this proposed method, and the power gain due to the fault identification is around 152% which is 97 W in the PV array.

Study of the overcurrent protection coordination for radial and ring fed system

The distribution systems are normally protected by inverse time overcurrent protection devices. This is due to the natural behavior to tolerate temporal overloading conditions on the distribution lines and its inexpensive cost. Therefore, both radial and ring fed distribution systems are protected using this protection principle. However, the manual time coordination procedure can be tedious and confusing for the new undergraduate protection students. For this reason, this article presents the overcurrent and directional overcurrent protection coordination study considering two parameter settings: time dial and pickup current.

Research on Design Principle and Process Design of Printed Circuit Board Type Overcurrent Protection Device for Chang’e-4 Popular Science Load Cable

The science popularization load of chang’e-4 is a high-density pressure resistant container with a diameter of 173 mm, a height of 198 mm and a weight of only 2.608 kg. It is loaded with cotton, rape, potato, Arabidopsis, yeast and Drosophila. With the successful landing of chang’e-4, this load has entered the growth and development mode of biological lunar surface. The data interface unit (DIU) of the lander provides the primary bus for the science popularization load system of Chang’e 4. The data interface unit provides no overcurrent protection measures for the power supply output. The science popularization load is provided with the command power supply by the lander system unit (SMU). The current limiting resistance of the power supply output is small, and there is moisture inside the science popularization load. In order to cope with the short circuit of the power supply bus and the command bus caused by the unexpected short circuit of the science popularization load power supply connector, In order to ensure the normal operation of popular science load equipment, the overcurrent protection design is considered on the power supply cable of popular science load.

Estimation Method of Short-Circuit Current Contribution of Inverter-Based Resources for Symmetrical Faults

This paper proposes a practical approach to estimate the symmetrical short-circuit current (SCC) levels in overcurrent protection devices (OCPDs) installed on radial feeders for any penetration level of inverter-based distributed energy resources (DERs). The proposed method restores the lost phase protection coordination by estimating SCC values and changing the TMS of OCPDs accordingly. The method is validated by comparing the results with simulations on the IEEE 34-Node Test Feeder using MATLAB/Simulink, which shows an average error of 1.5% and a maximum error of 3.0%. For a 100% penetration level, the SCC variation through OCPDs installed on the main fault trunk (MFT) exceeds ± 10%, leading to compromised phase protection coordination. The SCC flowing reversely through OCPDs on lateral branches and the fault on the MFT could cause improper tripping. Higher SCC levels are estimated and measured for fault impedances equal to zero. The phase protection is restored by changing the TMS of OCPDs using the estimated values. The study proposes two phase protection schemes to accommodate inverter-based DERs injecting 1.2 pu and 2.0 pu of SCC for a 100% penetration level. This study contributes to improving the protection coordination of distribution networks with high penetration levels of DERs. The findings have practical implications for distribution system operators and planners to maintain safe and reliable operation of distribution feeders.

Adaptive Protection for Active Distribution Networks: An Approach Based on Fuses and Relays With Multiple Setting Groups

Protection schemes are essential in active distribution networks and microgrids’ reliable, efficient, and flexible operation. However, the protection of these networks presents significant challenges due to operational changes, such as variations in topology, distributed energy resources connection/disconnection, and microgrid operating modes, among others. This paper proposes an adaptive protection scheme based on overcurrent devices with several setting groups based on artificial intelligence algorithms. The developed strategy is composed of two stages. In the off-line stage, a clustering technique is employed to group the active distribution network operating scenarios exhibiting similarities. The optimal settings for the protection devices are determined for each set of scenarios. On the other hand, in the on-line stage, the protection strategy’s implementation and operation, considering the active distribution network’s existing communication system, are defined. Furthermore, the approach formulates the overcurrent relay coordination as a mixed-integer non-linear optimization problem, and as a result, the optimal setting of the overcurrent protection devices is obtained. It aims to minimize the operating time, considering the transformers’ thermal limits, fuse operating curves, and overcurrent relay settings. The solution is determined by using an Augmented Lagrangian genetic algorithm. The presented protection scheme is validated on the modified IEEE 34 node test feeder, considering the main operating scenarios of the active distribution networks, such as topology changes, distributed energy resource connection/disconnection, and microgrid operating modes (on-grid and off-grid). The results obtained and its easy implementation indicates the high potential for real-life applications.

An adaptive fuse-saving protection scheme for active distribution networks

Electricity generation is one of the major concerns of today’s world due to increasing dependence on this energy. Continuity in power supply and service to network consumers may be disrupted by various disturbances; thus, the power grid requires a reliable and fast protection system. The protection of distribution networks is conventionally performed by overcurrent protective devices which preserving their coordination is a complex task due to bidirectional power flow resulting from the presence of distributed generation (DG) units. This paper presents an adaptive scheme to restore protection coordination in the distribution networks with a high penetration level of DG units. Using the multi-agent system (MAS) structure, the main protection technique monitors the current of the lateral fuse by an intelligent electronic device (IED) to estimate the operating time of the fuse and sends this data to the upstream recloser IED. Then, the recloser IED determines the recloser operating time to preserve the protection coordination. In the case of failing the main technique, the backup technique protects the distribution feeder by using a definite time piecewise linear curve for the recloser based on the proposed recloser current coefficient. The backup technique is independent of communication links. The reliable performance of the developed scheme is assessed on the ETAP simulation model of the IEEE 33 bus test system.

Accelerating Time–Current Curve Computation of Induction Motor from Manufacturer Data

Accelerating time–current (ATC) curves of induction motors are normally used for setting, selecting, and coordinating their overcurrent protective devices against heating. Conventionally, the ATC curves can be computed using commercial software tools via a dynamic simulation. This approach always needs a completed set of motor circuit-model parameters, which are typically unavailable to users. To eliminate this problem, this article addresses a direct approach to calculate the ATC curves from commonly available manufacturer data sheets of motors without using the sophisticated simulation tool. Mathematical models of motor’s torque and current curves, taking a nonlinear deep-bar effect into account, are proposed for the ATC determination. The computed torque and current profiles are validated by comparison with those generated from the Matlab simulation tool, published equivalent-circuit parameters, and field measurements. An accuracy of the obtained ATC curves is also assessed against those of the dynamic simulations. The satisfactory results are entirely obtained.

Magnetic coupling engineering-induced excellent spin transport in covalently linked nanographene dimers

A generally accepted viewpoint is that molecules with a spin S = 1/2 did not show any magnetic coupling when assembled into molecular dimers. However, a recent experiment successfully synthesizes covalently linked five-membered ring decorated nanographene dimers that are antiferromagnetically coupled with each other [Phys. Rev. Lett. 124 (2020) 147206]. Motivated by this work, we further study the effect of magnetic coupling engineering on spin transport properties in covalently linked nanographene dimers-based molecular devices. Our results show that excellent spin transport properties are strongly dependent on the magnetic coupling strength of the covalently linked five-membered ring decorated nanographenes. A variety of interesting spin transport properties are found, including “inverse Schottky” characteristic, high spin polarization, reverse of spin polarization, and large magnetoresistance. These results indicate that the covalently linked five-membered ring decorated nanographene dimers can be designed as over-current protection devices, and information storage and logic devices by engineering of magnetic coupling. Our works confirm an efficient way for building high-performance carbon-based molecular spintronic devices.

Load Currents Behavior in Distribution Feeders Dominated by Photovoltaic Distributed Generation

The distributed power generation (DG), like photovoltaic (PV) systems, promptly pleased consumers worldwide due to the availability of the source and the ease of installation. Despite the environmental advantages, it is known that the new generating sources connected to the power grid can provide modifications in the power flow, changing, for example, the load current values. Several papers were focused on present overcurrent protection solutions based on short-circuit current analysis. However, the power system protection depends not only on the short-circuit current, but also on the load current values. This work evaluates distinct scenarios, considering different combinations of topological locations and quantities of DG through the power system. The chosen feeder, IEEE-13 Node Test Feeder, was modelled in Simulink, in steady-state, considering a high penetration of small-scale Photovoltaic Distributed Generation Systems (PVDG). The analysis of current variability in specific buses of the feeder showed a reduction of more than 80% of the load current value for an extreme case. The results indicate that changes in the overcurrent protection devices (OCP) adjusts towards a massive insertion of DG can be fundamental to guarantee the sensitivity of the devices and a correct performance of it for overload.

Effect of the let-through energy of overcurrent protective devices on the temperature of conductors during short-circuits

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

Review of Technical Design and Safety Requirements for Vehicle Chargers and Their Infrastructure According to National Swedish and Harmonized European Standards

Battery electric vehicles demand a wide variety of charging networks, such as charging stations and wallboxes, to be set up in the future. The high charging power (typically in the range of a couple of kW up to a couple of hundred kW) and the possibly long duration of the charging process (up to more than 24 h) put some special requirements on the electrical infrastructure of charging stations, sockets, and plugs. This paper gives an overview of the technical design requirements and considerations for vehicle charging stations, sockets, and plugs, including their infrastructure, according to the Swedish Standard 4364000, “Low-voltage electrical installations—Rules for design and erection of electrical installations”, and the corresponding harmonized European standards. In detail, the four internationally categorized charging modes are explained and the preferable charging plugs, including their two-bus communication, according to European Directives are shown. The dimensioning of the supply lines and the proper selection of the overcurrent protection device, the insulation monitor, and the residual current device are described. Furthermore, a comprehensive overview of the required safety measures, such as the application of an isolation transformer or the implementation of an overvoltage protection mechanism, and the limits for conducted electromagnetic emissions, such as low-frequency harmonics or high-frequency (150 kHz to 108 MHz) emissions, are given.

A Control Strategy to Mitigate the Sensitivity Deterioration of Overcurrent Protection in Distribution Networks With the Higher Concentration of the Synchronous and Inverter-Based DG Units

This article focuses on the indeterminate protection challenge of the sensitivity deterioration (SD) (also known as protection blindness) of the overcurrent protection (OCP) devices due to the large-scale integration of distributed energy resources (DERs) in the unbalanced distribution networks (DNs). The protection blindness of the OCP has been demonstrated through novel mathematical formulations to quantify the percentage of the SD for different types of distributed generation (DG) units and for the varying DG penetration levels. Furthermore, this issue has been realistically analyzed for the different fault impedances and DG locations to examine its impact on the existing OCP system. A mitigation strategy has been proposed to overcome the SD issue of the OCP protective devices (PDs) for a steadfast operation of the OCP devices without requiring costly upgrades of the protection system. This protection blindness issue has been explored and the mitigation strategies have been tested for both synchronous and inverter-based DGs using the IEEE standardized test feeders. The proposed mitigation strategy has been validated in the IEEE 34-bus test system. The simulation results prove the effectiveness of the proposed mitigation strategy to restore the protection coordination and suitability to improve grid resilience.

Role of the interface on electron transport in electro‐conductive polymer‐matrix composite: A review

AbstractConductive polymer nanocomposites (CPC) are considered to be one of the best materials for the various applications like sensors, electrolyte membrane, photovoltaic cell, electromagnetic interference shielding materials, overcurrent protection devices, and many more due to the balance between electrical and mechanical properties, low cost, and ease of manufacturing. The most important aspect of an electro‐CPC is the interface between the polymer and conductive filler. In order to be electro‐conductive the fillers need not be in physical contact between them rather a few nanometer (typically ~10 nm) gap exist between two neighboring filler. Electrical conductivity of the composites arises from electron tunneling and hopping between conducting network. A typical way of preparing polymeric nanocomposites is the direct incorporation of inorganic nanoparticulate filler into polymers. Primarily focus has been given to carbonaceous nanoparticles in this article. Nanoparticles are an automatic choice for preparing the nanocomposites owing to their high‐interfacial interaction. However, it is often very difficult to well disperse nanoparticles in polymers because the nano particles with high‐surface energy are easy to agglomerate, which in turn adversely affects electron conduction in nanocomposites. One of the most used techniques to overcome this difficulty is to modify the interface of the polymer and filler as often the interface between polymer and filler played a crucial role in electron conduction. The aim of this review article is to report the most recent developments in improving the interface of filler and polymers in CPC. The discussions are primarily focused on different methodologies for the preparation of CPC characterization of the interface and finally interface modification techniques.

Protection philosophy in low short‐circuit capacity distribution grids with high penetration of converter‐interfaced distributed renewable energy sources

The ever-growing penetration of converter-interfaced distributed renewable energy sources (CI-DRES) in distribution networks, despite the undoubted advantages, has a profound impact on the traditional protection systems. The protection problem becomes even more complicated as the increase in the CI-DRES penetration level leads to the decommissioning of conventional power plants. Due to the limited current capability of CI-DRES, decommissioning of conventional units will lead to a transmission grid of significantly lower short-circuit level. This study proposes a novel protection philosophy for distribution grids of low short-circuit capacity and high CI-DRES penetration. According to the proposed approach, CI-DRES are controlled to actively participate in the fault-clearing procedure, supporting the short-circuit capacity, in an aggregated form, through the injection of controllable currents. Therefore, conventional overcurrent protection devices can be used, without any additional investments for a protection system upgrade. The CI-DRES fault contribution is based on their relative position to the fault, respecting technical and protection-malfunction constraints. In addition to the short-circuit level, the effect of the feeder parameters and the power factor of the injected fault current on the voltage recovery is also investigated. The proposed protection philosophy is validated via detailed simulations in DIgSILENT PowerFactory.