Short-circuit Protection Research Articles

Releasers with electro-hydraulic retarders as an effective alternative for short circuit and overcurrent protection

It is known that circuit breakers (CBs) installed in distribution cabinets (DCs), better known as “enclosed circuit breakers”, depending on the execution, are designed for: - protection against emergency states of grids: overvoltage and short circuit (s/c) or voltage drop below the permissible level (circuit breakers installed on the grid do not always provide protection against voltage reduction); - protection of AC motors, as well as for combined installation with other electric devices (CBs can service by grid sections as well as separate motors if CBs are used to operate the wound-rotor motor or starting devices, they must include voltage drop protection); - to be used as disconnectors for supply and trunk networks. Overcurrent protection is done by a bimetallic plate, while an electromagnetic releaser provides s/c protection. The main features inherent in this technical solution of overcurrent protection include: - relative dependence on ambient temperature; - inability to quickly switch on again after the CB is triggered; - unstable time-current characteristics of the CB. National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” and «E.NEXT Ukraine» offers an alternative solution for the design of CB protection elements, which is an integrated overcurrent and short circuit protection at the same time in the form of a releaser with an electro – hydraulic retarder. A releaser with an electro-hydraulic retarder triggers the СB actuator, which breaks the contact group of the CB when the current exceeding the set maximum permissible value (s/c or overcurrent) is passing through electrical equipment. The main part of this releaser is an electromagnet, whose coil is connected in series with working contacts in the circuit of the operating current.

Implementasi Parameter Sistem Pentanahan Generator Melalui Transformator Distribusi Menggunakan Labview

Determination of the generator neutral grounding system through a distribution transformer can be done through manual calculations. Many parameters are considered in the calculation to get the appropriate results there is the possibility of repeated calculations. This is very difficult and causes a large difference in the calculation results. Therefore, a computer-based computing system is needed to overcome this kind of problem. Several papers have developed the calculation of the required generator neutral earthing magnitude which considers the voltage level, short-circuit fault current and protection system against ground faults. This paper discusses modeling in designing generator neutral ground using the LabView Graphical User Interface (GUI) application. The goal is to be easier, faster and more accurate. As the implementation of the modeling used data from std C62.92.2TM-2017.

Open-Circuit Fault Characteristics and Location Methods of Switch Elements For Cascaded Power Electronic Transformers

Power electronic transformers (PETs) play an important role in AC/DC hybrid distribution networks. However, the fault probability of a PET is higher because of the use of many power electronic devices. The short-circuit protection of a PET is relatively mature, but studies on its open-circuit faults are limited to insulated gate bipolar transistors (IGBTs) in the cascaded H-bridge (CHB). Therefore, other types of open-circuit faults result in dead zones in the fault location process. In this article, the open-circuit fault characteristics of switch elements at different positions of a PET are analyzed, and a protection circuit is designed for the possible overvoltage caused by the open-circuit fault in the CHB. Moreover, the fault location methods of switch element open-circuit faults are proposed. The proposed methods could adapt to the diversity of control modes, power directions and load levels. The correctness and effectiveness of the methods are verified via simulation tests. This work provides a basis for the implementation of fault-tolerant control and protection of PETs.

Superior Short circuit & Overcurrent Protection of Devices like Alternator, Transformer etc.

Improved motor, controller and branch circuit protection has been the subject of a never-ending stream of magazine articles, IEEE papers and amendments to the National Electrical Code. Combining motor short-circuit protectors and properly certified motor controllers may provide superior branch circuit overcurrent protection. An Alternator, Transformer, and Other Devices with Superior Short Circuit and Overcurrent Protection are discussed in this study.

Superior Short circuit & Overcurrent Protection of Devices like Alternator, Transformer etc.

Improved motor, controller and branch circuit protection has been the subject of a never-ending stream of magazine articles, IEEE papers and amendments to the National Electrical Code. Combining motor short-circuit protectors and properly certified motor controllers may provide superior branch circuit overcurrent protection. An Alternator, Transformer, and Other Devices with Superior Short Circuit and Overcurrent Protection are discussed in this study.

A Low-Power Hiccup-Mode Short-Circuit Protection Technique for DC-DC Boost Converter

An improved low-power hiccup-mode technology for short-circuit protection is proposed in this paper, which can effectively suppress short-circuit currents and greatly minimize the power dissipation of hiccup mode. The circuit can start normally after the short circuit is recovered, and there is no voltage overshoot. At the same time, the proposed pre-charge circuit can effectively suppress the large initial inrush current in the pre-charge stage. These technologies are used in a Peak-Current-Mode-Control (PCMC) Pulse-Width-Modulation (PWM) DC-DC boost converter designed with a 0.35 standard CMOS process. Compared with the conventional structure, the post-simulation results show that the initial inrush current during the start-up phase in the proposed structure is reduced by about 90%. When the output short circuit occurs, the inductor current drops to approximately zero and the power dissipation of the converter is very low at this time. The converter repeatedly detects the state of the output load after a period of about 24 ms. Eventually, the converter will restart after the short circuit is recovered and there is no voltage overshoot.

A fast and cost-effective short circuit protection scheme for low-power converters for small-scale photovoltaic application

PurposeThis paper aims to propose an integrated protection scheme for converters of a low-power, low-cost photovoltaic system. Power electronic converters use a variety of methods to limit overload and fault current. The use of insulated and non-insulated sensors along with additional circuits to detect and limit fault current can cause current to be limited or completely cut off before damage to semiconductor devices. In addition, fuses that have slower performance are used as backup for any type of protection.Design/methodology/approachFirst, all the candidate points for protection are investigated. In this paper, after examining the performance of glass fuses as linear resistors, they are used as a current feedback element. A simple, isolated and reliable circuit for fault detection at various points of the system has been proposed that can be implemented and operated in single shot or auto-reclose operating mode.FindingsThe experimental results of this circuit on a dc/dc converter and an H-bridge inverter show that it can cut off all instantaneous short circuit errors in less than 50 µs and prevent damage to the semiconductor switch.Originality/valueIn low-cost and low-power converters, it is usually not cost-effective to use complex and expensive devices. For this reason, these converters are more vulnerable to faults. On the other hand, in complex systems such as photovoltaics, several converters are used simultaneously in different parts, and the occurrence of a fault in each of them causes the whole system to fail.

Analysis Of Motor Chiller Safety System In Store Building

Security of the chiller is very necessary, especially to protect the motor from interference so that it can also protect the chiller from damage that occurs, in addition to protecting the surrounding environment and living things (humans). Disturbances that arise in the chiller can be caused by current and voltage, unstable loads on the motor or from its environment; This can cause damage to the motor, fire and death. The safety equipment used in the chiller motor safety system can be in the form of circuit breakers (MCCB and ELCB) or Phase Failure Relay (Motor Saver). MCCB is used as short circuit, overload and overcurrent protection; ELCB for leakage current; while the Motor Saver is used for safety of less/over voltage, asymmetrical voltage.

Design and Simulation of Selective Short Circuit Protection System in AC Microgrid with Grid-connected Mode

The fast detection and accurate location on short-circuit faults has always been the research direction of AC microgrid fault protection. A short-circuit fault protection system for grid-connected AC microgrid is designed based on dsPIC33FJ32GP204 in this paper, which realizes the fast detection and regional location. The short-circuit fault simulation model is built on PSCAD, and all kinds of fault waveforms generated by simulation are imported into Proteus. The designed protection system is used to transform the wavelet energy spectrum of all kinds of fault waveforms generated by simulation, and then output the corresponding control signal to circuit breakers. Simulation results show that the control system can quickly perceive and accurately locate the microgrid short-circuit fault area and realize the output of selective protection signal.

A Comprehensive Short-Circuit Protection Scheme for Series-Connected SiC MOSFETs

Series connection of devices is an effective way to achieve higher blocking voltage. SiC MOSFETs exhibit narrow short-circuit withstand time and generally much lower short-circuit robustness than silicon IGBTs. This puts a critical concern on their utilization, further stressing the importance of reliable protection. A complete short-circuit protection should be implemented to improve the reliability. In this article, a systematic short-circuit analysis methodology is proposed. Following this methodology, all the possible fault scenarios can be derived. Besides the traditional short-circuit scenarios, some unique short-circuit faults, such as a single device short- or open- circuit, have been found in series-connected SiC MOSFETs. These unique faults may not cause overcurrent, which means the traditional overcurrent-based protection is not applicable. This article proposes a method combining drain-source voltage logic signal and gate signal to comprehensively detect both classic short-circuit scenarios and unique fault scenarios. Another different point in series-connected devices is that the soft turn-off should be synchronized for each serial device to prevent excessive voltage unbalancing. The proposed short-circuit protection scheme is evaluated under each short-circuit scenario. The experimental results demonstrate that the proposed protection scheme can successfully protect the serial devices from further destruction within 500 ns for all short-circuit scenarios.

SIMULATION OF TRANSFORMER DIFFERENTIAL PROTECTION IN THE MATLAB ENVIRONMENT

Currently, relay protection is based on microprocessor units, which have expanded functionality in comparison with traditional electromechanical means. For the correct operation of these devices, it is necessary to enter the actuation settings, which are calculated manually taking into account the characteristics of a particular power system. Modeling of relay protections in the MatLab environment allows reducing the role of the human factor and minimizing possible errors. (Research purpose) The research purpose is to develop a model of differential relay protection of the transformer in the MatLab Simulink environment. (Materials and methods) The article presents a model of a power system with a power two-winding transformer and differential relay protection with the functions of a current cut-off, differential protection with bias and blocking of the magnetization current surge. (Results and discussion) In the external short-circuit mode, the current protection does not acts, which indicates that the differential protection against external short circuits is detuned. In the short-circuit mode, current cut-off and protection with bias are triggered from the sides of the lower and higher voltages, which also indicates the adequacy of the model. Testing in the magnetization current surge showed that with the 0.15 detuning setpoint recommended by manufacturers of relay protection devices, the protection is blocked for more than 15 seconds, which is unacceptable in practice. The adequate operation of the relay protection is noted at a setpoint of 0.7. The dependence of the harmonic composition of the magnetization current surge on the switching moment on the transformer relative to the transition of the supply voltage through zero was revealed. (Conclusions) The developed model implements the functions of differential protection of the transformer, adequately reproduces all the processes of digital signal processing in microprocessor relay protection units, allows you to check the correctness of functioning in different modes and at different actuation settings.

Design of short-circuit protection circuit for switching power supply

Short-circuit protection circuit for switching power supply is designed. The circuit is for sampling and protection based on capacitance ripple characteristics. It has the advantages of rapid fault protection adjustable trigger time and recovery time. It shows that the circuit scheme has a good protective effect on the power converter in various load environments, and it has reached desired effect, according to the simulation results and the circuit application results.

A New Method of Coordinating ZCBs and Fuses for a Reliable Short-Circuit Protection in DC Power Networks

A New Method of Coordinating ZCBs and Fuses for a Reliable Short-Circuit Protection in DC Power Networks

An improved desaturation short-circuit protection method for SiC power modules

Silicon Carbide (SiC) MOSFET devices have smaller chip size and higher current density than Si counterparts, which results in the limited short-circuit capability of SiC power modules. The presently used protection circuit is actually conventional desaturation protection method, which is very suitable for IGBT modules. But this conventional protection circuit has relatively slow response, and cannot be directly used in SiC modules due to its higher di/dt and weaker ruggedness compared to IGBT modules. So we propose an improved desaturation protection method. We first analyse the short-circuit process to obtain the short circuit characteristics of SiC MOSFET. Then, we give the principle of the improved desaturation protection method, and present the comparison between the conventional protection circuit and the improved one. At last, short-circuit protection tests under HSF and FUL faults have been conducted to verify the improved desaturation protection circuit. The experimental results show that the improved desaturation protection circuit has a faster response than the traditional one, and can make SiC modules work reliably.

Four Channel 6.5 kV, 65 A, 100 ns–100 µs Generator with Advanced Control of Pulse and Burst Protocols for Biomedical and Biotechnological Applications

Pulsed electric fields in the sub-microsecond range are being increasingly used in biomedical and biotechnology applications, where the demand for high-voltage and high-frequency pulse generators with enhanced performance and pulse flexibility is pushing the limits of pulse power solid state technology. In the scope of this article, a new pulsed generator, which includes four independent MOSFET based Marx modulators, operating individually or combined, controlled from a computer user interface, is described. The generator is capable of applying different pulse shapes, from unipolar to bipolar pulses into biological loads, in symmetric and asymmetric modes, with voltages up to 6.5 kV and currents up to 65 A, in pulse widths from 100 ns to 100 µs, including short-circuit protection, current and voltage monitoring. This new scientific tool can open new research possibility due to the flexibility it provides in pulse generation, particularly in adjusting pulse width, polarity, and amplitude from pulse-to-pulse. It also permits operating in burst mode up to 5 MHz in four independent channels, for example in the application of synchronized asymmetric bipolar pulses, which is shown together with other characteristics of the generator.

A Digital Signal Processing Based Detection Circuit for Short-Circuit Protection of SiC MOSFET

A short-circuit detection (SCD) circuit is proposed for power electronics systems that use silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs). The proposed SCD circuit incorporates a digital circuit for processing the voltage induced at the parasitic inductance of the source of SiC MOSFET to obtain an improved stable turn-off operation of the SiC MOSFET under SC condition. Compared with that of the conventional analog signal processing based SCD circuits, the proposed circuit has the advantages of having a turn-off operation which is robust to process, voltage, and temperature variations, being fully integrated without the use of external components and ease of design. The proposed circuit was implemented in a 350-nm Bipolar-CMOS-DMOS process. For functional verification, an SC test board integrating the proposed SCD circuit was developed. Experimental result validates that the proposed SCD circuit effectively functions under SC condition.

A short circuit protection circuit for SiC MOSFET with self-adjustive blanking time

This paper proposed a desaturation (DESAT) short circuit (SC) protection circuit for SiC MOSFET, where a blanking time setting module and an SC detection module are designed. The fall time of the drain-source voltage (VDS) for each switching period of SiC MOSFET is recorded and set as the blanking time for the hard switching fault (HSF) detection in the next switching period. Consequently, the detection delay for HSF is self-adjustive and can respond quickly to the operating state of SiC MOSFET. FPGA and discrete components are used to implement the proposed circuit. The function of the proposed circuit is verified using the double pulse test. The experiment results show that the blanking time automatically increases with the increase of load current. The default detection delay of the proposed protection circuit is set 240ns for HSF and can be adjusted during the subsequent switching period. So in the test under a 400V bus voltage, the detection delay is 240ns for HSF at the first switching period. And for HSF occurs at the second switching period, the detection delay is 200ns adjusted according to the operating state of the first switching period. Meanwhile, the detection delay for fault under load (FUL) is 72ns.

(Invited) 75 kVA 1kV DC 50 kHz Air-Cooled Inverter with 1.7 Kv SiC Mosfet and 3D-Printed Novel Modular Packaging Structure

In recent years, some air-cooled inverters have been developed and demonstrated for grid applications using SiC power modules. All of these SiC power modules utilize the conventional single-side wire-bonding packaging structure, i.e. only one side of the power module is attached to heat sinks. The potential of silicon carbide (SiC) devices, such as high power density, high frequency and high temperature operation, have not been fully explored yet. To deal with this issue, several research efforts have focused on the development of SiC power modules with double sided-cooling capability, utilizing planar packaging structure . These power modules are able to achieve a comprehensive improvement in overall volume / size, parasitic parameters, as well as thermal impedance. However, some key aspects limit the real application of planar packaging structures. One main reason is that double-side solderable SiC devices are generally not commercially available. Other challenges include interconnection alignment issue, limited choices for die-attach material, complicated fabrication process, etc With the goal of exploring SiC device potential without complicated packaging, an all-SiC air-cooled wire-bonding power module and inverter is developed for grid applications based on 3D printing technology enabling: new packaging structure, optimized heat sink, and more-compact system integration.This paper presents the design and development of an 75 kVA, 50 kHz, 1kV air-cooled Silicon Carbide inverter using advance packaging and additive manufacturing technology. Specifically, an air-cooled power module with a new packaging structure is design, aiming at reduced thermal resistance for high temperature and high-power density operation. The detailed research work involves the design of a new packaging structure, wire-bond SiC power module design and fabrication, as well as associated power stage and control circuit design. The total volume of the power module for the prototype is 99725 mm3 a 48% volume reduction volume compared to previous work reported by the authors. The air-cooled module assembly incorporates three major parts: SiC MOSFET phase leg module with split high side and low side switches, a gate driver with cross-talk and short circuit protection functions, and 3D printed module package. In addition , the thermal performance of the inverter is also evaluated and the results show the maximum junction temperature of the bare die is 103C. Based on the air cool module, a 50-kW three phase inverter is developed and tested to further verify the superior thermal performance of the proposed packaging structure. The experimental results show that the peak efficiency is 99.1% at 1kV,50 KHz switching and 50 kW operating condition. Figure 1

Layout-Based Ultrafast Short-Circuit Protection Technique for Parallel-Connected GaN HEMTs

Gallium-nitrideenhancement-mode high-electron-mobility transistors (GaN HEMTs) help to achieve high-power-density converter circuits due to their superior efficiency, higher switching speed, and small package size. However, increased switching speed results in a sharp increase in short-circuit (SC) current under a shoot-through fault with respect to other type of devices. GaN HEMTs can withstand the SC current only for several hundred nanoseconds. Therefore, fast SC protection solutions are critical for protecting power circuits. In this article, the voltage induced by high slew rate of SC current on the high-frequency power loop inductance resulting from the printed circuit board (PCB) layout is sensed to implement an ultrafast short-circuit protection technique. The proposed technique does not increase circuit parasitics and provides flexibility in layout design that makes it suitable for parallel-connected GaN HEMTs, which requires symmetric layout design for equal current sharing. A multipulse test is conducted under 1.56-MHz switching frequency, 400-V dc- bus voltage, and 40-A load current by using parallel-connected GaN HEMTs in a half-bridge configuration to verify the robustness and reliability of the proposed protection technique. Experimental results show that the proposed protection technique can detect SC fault within 40 ns and fault is completely cleared with a soft turn-off in 250 ns.

Overcurrent protection against multi-phase faults in MV networks based on negative and zero sequence criteria

Adequate power system protection plays crucial role in ensuring reliability of electricity supply, thus it is a key challenge for distribution system operators to increase the effectiveness of protection schemes operation and protection equipment itself. The main goal of the paper is presenting a multi-criteria protection algorithm that may boost effectiveness of power lines’ short-circuit overcurrent relays in medium voltage networks in case of various two phase faults. The idea of enhancing protection performance is based on fault current symmetrical components’ analysis and specifically on using negative and zero sequence currents as criterial values for overcurrent line protection used against such faults. The paper describes in detail the proposed solution and analyses its performance based on medium voltage network simulations carried out using DIgSILENT PowerFactory software. Promising simulation results can be observed for definite time overcurrent protection relays used in reactance-earthed networks, as introduction of the proposed method proved to increase the zone of effective operation twice comparing to the traditional phase current based solutions. Moreover, in the proposed solution, coordination of protection settings for small earth-fault current values, which are identified by other protection relays, is not necessary. The proposed solution may complement the traditional algorithms for short-circuit protection (I≫) used in modern protection relays monitoring the level of negative and zero sequence current, and therefore may significantly improve the effectiveness of detecting various phase-to-phase faults in the considered MV line protection zone.