Short-circuit Tests Research Articles

Parameters Estimation Tests of Induction Machine Using Matlab/Simulink

This paper describes special tests through the Matlab/Simulink program with induction machine to estimate the parameters of the equivalent circuit step by step because they have a direct impact on the performance of induction machine while running steady-state machines and dynamic status. There are three tests to determine the parameters of the induction machine (R 1, R 2, X 1, X 2, X m) is a DC test and No-Load test (open-circuit test) and Blocked rotor test (short-circuit test). Despite the fact that temperature and the skin effect are not taken into account in DC resistance modelling, the results obtained are approximate and rational. For control and verification, the parameters of an induction machine can be accessed through the above three tests. Simulation and experimental results confirm the effectiveness of the proposed method. This work can be easily applied by students to enable them to know the parameters in the absence of the information provided in the motor.

Sterilization of Dry-Type Transformer Winding by Conducting Short-Circuit Test in Nuclear Power Plant: A Case Study

Sterilization of Dry-Type Transformer Winding by Conducting Short-Circuit Test in Nuclear Power Plant: A Case Study

Li-Ion Battery Deactivation through External Short Circuit

While electric vehicle battery packs are designed to address safety issues, battery failures can still occur. Most prominently, electric vehicle fires can occur after accidents or from internal shorts due to defects, abuse, or accelerated aging. Battery fires can be difficult to manage due to the active lithium materials and the presence of both the fuel and oxidant produced by thermal decomposition. Typically, after extinguishing the original fire, the main priority is to cool the battery pack by applying a large and continuous volume of water directly to the pack. However, the fire may still reignite hours later, fueled by the remaining stored energy. This highlights the need for further investigation and discussion about how to effectively remove the stored energy from, or deactivate, batteries with the goal to prevent fire re-ignition in battery packs.Batteries at a lower state-of-charge (SOC) are more thermally stable and have a lower energy release during thermal runaway than those at high SOCs. In addition, experimental results from single cells and small, multiple-cell configurations undergoing external short circuits show that thermal runaway (TR) events are rare, and the cell peak temperatures depend on the relative size of the external resistance to the internal cell resistance. To this end, this research aims to evaluate the use of high C-rate discharge and external short circuits to safely deactivate batteries while avoiding TR.External short circuit testing was performed on 4.6Ah pouch cells at 15% and 100% SOC, with measurements of cell current, voltage, temperature, expansion force, and atmospheric CO2 gas concentration. At the end of the test, the cell initially at 15% SOC discharged to -10% SOC and reached a maximum temperature of 64℃. The cell had no visible damage afterwards. For the 100% SOC cell, it reached a maximum temperature of 120℃ and discharged to around 25% SOC at the end. In both cases, neither went into thermal runaway, but the first cell was able to discharge to less than 0% SOC in 5 minutes, while the 100%SOC cell took significantly longer to reach the low current cutoff. This is because during the gas venting process, electrolyte is lost, greatly increasing the internal resistance and increasing the discharge time. In addition, the lower peak temperature of the first cell indicates a reduced likelihood of thermal runaway propagation in a pack, and the lack of toxic and flammable vent gas and electrolyte leakage in the environment improves safety. In order to apply this at a larger level, we will investigate the appropriate external resistance to safely deactivate the cells without leading to hazardous conditions. Figure 1

Develop an Activation Pressure Measurement Method of the Safety Vent and Investigate the Relationship between Cell Safety Devices' Activation Pressure and LIB Cell Safety

The current interrupt device (CID) and vent mechanism in the Cylindrical cells are a fuse-type safety device that permanently disconnects the cell's electrical circuit and releases internal pressure when triggered by excessive cell pressure by abnormal conditions to keeps the cell safe from the thermal runaway risks. Compared to the importance of the safety devices' activation pressure, the test method and apply the techniques to the cell characterization was not defined adequately.This research developed the test methods, procedures, and equipment to measure the activation pressure accurately of both the CID and vent mechanism simultaneously. We select four different cell markers' commercial 18650 cell models with about 3.5 Ah nominal capacity to evaluate the cell model's safety level and to identify the relationship between the activation pressure level and the safety test item: electrical, mechanical, environmental (Thermal) abnormal impacts.To investigate the relationship between cell safety devices' activation pressure and the cell model's safety, we performed some cell safety tests and cell model design checks. The cell alignment check with the electrode gap measurement, including some electrical tests, checks the test samples' quality status. Cell safety tests include thermal safety, external short circuit, nail penetration, impact, and crush test. Each safety test item's test condition and procedure are referenced from widely accepted cell safety standards and battery industrial best practices for the lithium-ion battery.The activation pressure of the CID and vent mechanism was measured simultaneously by detecting the cell voltage changes and applied pressure to vent, respectively. All four cell models have shown that the CID was always activated earlier at a lower pressure than the vent mechanism. The activation pressure of the CID and the vent mechanism of the four cell models were different by manufacturers. The tolerance and the activation pressure gap between CID and the vent mechanism of each cell model were different among the four cell models.The cell safety test items can be classified by 1) thermal and electric abuse test and 2) mechanical abuse test. We used the EUCAR Hazard Level to evaluate the safety level of each test item items. The table explains each test item's safety level of the four cell models according to the EUCAR Hazard Level criteria. The cell hazard levels of the thermal and electric abuse test items (thermal safety and external short circuit test) are strongly affected by the activation pressure level of the CID and vent mechanisms. The detailed investigation concluded that the CID's activation pressure level affects more than that of the vent mechanism to the thermal and electric abuse test items' hazard level. These results are derived from the fact that the safety device activates in advance at a lower pressure than the cell enclosure's opening.Meanwhile, the cell hazard levels of the mechanical abuse test items (nail penetration, impact, and crush test) were not affected by the safety devices' activation pressure level. Because the mechanical abuse test items always opened the cell enclosure in advance compared to the safety device activation.This research proposes to add the activation pressure level of the cell safety devices to the EUCAR Hazard Level criterion to enhance the efficiency of evaluating the cell models' hazard level. That can provide more worthy criteria for the cell selection and cell safety evaluation process for the multi-cell battery system design. Figure 1

Detection of First Venting in Battery Failures with Carbon Dioxide Sensors

Li-ion battery thermal runaway is a critical safety issue for large-scale battery packs. Upon battery failure, gas venting can occur when the cell's internal pressure exceeds a critical value and causes cell rupture and electrolyte leakage. The gas venting is usually categorized into first venting events and thermal runaway gas venting events (second venting). The first venting occurs around 120 °C and can be considered as a precursor to thermal runaway. The subsequent venting during thermal runaway is more aggressive and releases more vent-gas.Detecting battery failures immediately after the first venting is critical to take action before the failure evolves into a thermal runaway event. Therefore, a gas detection method targeting first venting gas will be the focus. Early studies of first venting gas composition showed that CO2 is the primary gas component in battery overheating tests, nail penetration tests, and overcharging tests, while the gas composition in battery external short circuit tests was not revealed.To this end, an external short circuit test for a pouch 4.6 Ah cell was performed in a non-sealed acrylic box, which has around 21.5 L volume. Shortly after the initiation of external short circuit, the battery expansion force rises due to gas generation inside the pouch cell. The force then dropped suddenly indicating a gas venting event, which occurred when the cell temperature reached 114 °C. A Non-Dispersive Infrared (NDIR) CO2 sensor was used. The CO2 sensor reading started to increase within 5 seconds of gas venting and reached a maximum of 1,500 ppm as shown in the figure.To apply the gas detection strategies for first venting events, a detection threshold is required for different cells at different abuse conditions. To model the gas evolution process, the evolution of side reactions, mainly the SEI decomposition at high temperatures was considered. The released CO2 in first venting events can be estimated at different abuse conditions. The estimated CO2 amount can help determine the detection threshold of gas concentration for a given battery system. Figure 1

New method for fast coupled magnetic field-circuit simulation of power transformers based on a semi-analytical approach

A novel mesh-free methodology for the coupled magnetic field-circuit simulation of power transformers is presented in this paper. The proposed methodology employs equivalent models for the conductors and the iron core, which are based on the field produced by elementary geometric configurations and boundary conditions derived from Ampere's and Faraday's laws. Power losses in the windings due to circulating currents are calculated with the proposed method and the Finite Element Method (FEM). A 25 MVA transformer is investigated as a case study and the effect of the conductor connections within the windings is considered through its incidence matrix. The windings losses obtained by applying the proposed methodology are compared with the losses estimated from the short circuit test showing an excellent agreement. The computational performance is also compared with FEM. It has been found that the proposed method is about 9 times faster than FEM retaining the level of precision required for transformer design purposes.

A Novel Method for Distribution Transformer Short-circuit Test

Short-circuit test of distribution transformer is an important test to check out the short-circuit resistance of distribution transformer. This paper presents a novel short-circuit test method of distribution transformer based on energy storage short-circuit test device, which can complete the short-circuit field test of distribution transformer. The basic principle of the device is introduced, and the feasibility of the method is verified by simulation and experiment.

HTS FCL Module With Voltage of 500 V for DC Circuit Breaker

We have studied the operation of the circuit breaker for 15 kV DC power grid with the combination of the breaker and the HTS Fault Current Limiter (FCL). The HTS FCL limits the fault current by introduce of the impedance under the fault condition, so the circuit breaker with the HTS FCL module can be expected to be able to break the higher prospective fault current successfully. As an attached module to the DC circuit breaker, we performed a design work for a DC resistive HTS FCL module with SuNAM's REBCO conductor with the stainless-steel stabilizer. Considering the operation delay time of the DC circuit breaker, the HTS FCL module should generate a proper impedance for 16 milliseconds at most without any damages. To verify the design results, we designed and make scaled-down model of the HTS FCL module. We also carried out the DC short-circuit test to check the feasibility and the fault current limiting characteristics of the suggested model.

Short circuit detection and driving control with no blanking time for high voltage high power insulated gate bipolar transistors

Insulated gate bipolar transistors (IGBT) short-circuit (SC) protection is one of the most important protection methods for IGBT converter equipment. The fast detection and protection response time could reduce the permanent damage of devices, and extend their use life cycle. At present, the collector emitter voltage vce desaturation method is widely used in the commercial IGBT drive circuit, which has blanking time of fault detection and protection. In this paper, an improved adaptive vce SC detection and protection is proposed to realize the blanking time adjustment under different SC conditions. By the determination of the di/dt characteristics of the current variation on the parasitic inductance between the power emitter and the Kelvin emitter of IGBT modules, the execution time of the two detection methods can be set. According to the switch process and the SC type, the corresponding logic processing will be carried out to realize the fast detection of different SC conditions. The circuit scheme without blanking time detection and protection is designed, and the circuit is modelled and simulated by Pspice. The IGBT driving circuit SC test without blanking time detection and soft turn-off protection has been carried out. Simulation and test results can verify the feasibility of the proposed circuit.

A coupling method of the superconducting devices modeled by finite element method with the lumped parameters electrical circuit

Superconducting devices have been widely studied over these years. Their application can be found in cables for electric power transmission, energy storage systems, magnetic levitation, electric machines, and fault current limiters. The literature presents some formulations to model the superconductors’ behavior using the finite element method (FEM), such as the H, the AV, and the T formulations, among others. Many superconducting devices have been simulated and designed using some of these formulations. However, none method available offers a coupling between an electric power system, simulated using electrical lumped parameters, to the superconducting FEM model. In this context, this work introduces a methodology for coupling superconducting devices in FEM to lumped parameters composing the power system. Here, a case study with a Saturated Iron Core Superconducting Fault Current Limiter was presented to apply the proposed methodology. This research analyzes the influence of the self and external fields in the superconducting coil on its critical current density. Moreover, it investigates the DC-biased coil voltage drop and the superconducting resistance. Besides, the paper presents the simulations of short circuits for various DC currents applied to the superconducting coil. Short-circuit tests were performed for validating the simulation results, and it showed a maximum error of 15% for the compared points.

A High-Resolution In Situ Condition Monitoring Circuit for SiC Gate Turn-Off Thyristor in Grid Applications

Silicon carbide (SiC) gate turn-off (GTO) thyristor is attractive for grid applications due to the excellent performances of high blocking voltage and low ON-resistance. However, the short-circuit reliability issue has become one of the limiting factors. An in situ condition monitoring method for the reliability of SiC GTO is presented in this work. It uses the forward I- V characteristics of anode-gate p-n junction as the reliability degradation precursor of SiC GTO. The monitoring circuit shows a current resolution of 64 μA with the current range of -31~1027 mA. It provides full electrical isolation with 2-kV isolation voltage. Finally, a set of short-circuit power cycling tests are conducted with the monitoring circuit, and the results show that the method proposed in this article can effectively detect the change of I- V characteristics of SiC GTO to predict the degradation of device physical health.

DC Current Limiting Characteristics of Flux-Coupled Type SFCL Using Superconducting Element Connected in Parallel in a DC System

In this paper, the fault current limiting (FCL) characteristics of a flux-coupled type superconducting fault current limiter (SFCL) with parallel connection between two windings in a DC system were analyzed. The flux-coupled type SFCL was composed of two coils connected in parallel and a superconducting element (SE), which was connected in series with the secondary coil. The flux-coupled type SFCL works in DC systems similar to those in AC systems. Before a fault occurs, the respective magnetic fluxes generated by the two coils connected in parallel offset each other, maintaining the voltage induced in the two coils at zero. In case of a fault, however, resistance is generated in the SE, preventing the magnetic fluxes generated by the two coils from offsetting each other. Thus, some voltage is induced in the two coils, and this starts to limit the fault current. DC short circuit tests were conducted, and the test results confirmed that the flux-coupled type SFCL with the two parallel connected coils was effective in limiting the fault current in a DC system. Additionally, the effect of the wiring direction of the two coils on the SFCL’s FCL performance and operating current, limiting impedance, and instantaneous power load was further analyzed, and as a result, the performance conditions of the SFCL in a DC system were determined.

Leakage Inductance Representation for a Magnetic Circuit Model of Three-Winding Transformers for Electromagnetic Transient Analysis

In order to study electromagnetic transient phenomena occurring in power systems such as inrush currents or ferroresonance, an accurate and practical three-winding transformer model is required because the power system to be studied includes three-winding transformers in many cases. Although a star-circuit representation (Steinmetz's equivalent circuit model) is often used for these kinds of studies, it sometimes causes numerical instability because its magnetizing circuit representation is inappropriate. A magnetic circuit model considering iron-core topology is capable of eliminating the problem. However, the conventional three-winding magnetic circuit model does not match the leakage inductance measurements (short circuit tests) of the transformer to be represented. In this paper, we develop the three-winding magnetic circuit model which can match the leakage inductance measurements by making use of mutually coupled magnetic resistances. As a result of verification using a 500 VA single-phase three-winding transformer, it is indicated that the leakage inductance calculated by the developed model are in good agreement with those obtained by the leakage inductance measurements of the test transformer.

Effects of the Nail Geometry and Humidity on the Nail Penetration of High-Energy Density Lithium Ion Batteries

Internal short-circuit tests were carried out in a battery safety investigation chamber to determine the behavior of batteries during the nail penetration test. So far, systematic investigations regarding the test setup and its influence are rarely found in the literature. Especially, to improve the comparability of the multitude of available results, it is essential to understand the effects of the geometric, operating and ambient parameters. In this study commercial lithium ion batteries with a capacity of 5.3 and 3.3 Ah were used to study the influence of the varied parameters on the voltage drop, the development of surface temperatures and of infrared active gas species. We studied both the influence of the geometry of the penetrating nail and concentration of water in the inert atmosphere especially on the quantities of the reaction products under variation of cell capacity. It could be shown that the geometry of the nail, within certain limits, has no influence on the processes of the thermal runaway of high energy density lithium ion batteries (LIBs). However, a change in capacity from 5.3 to 3.3 Ah shows that in particular the gaseous reaction products differ: The standardized gas concentrations show a higher measurable concentration of all gases except CO for the 3.3 Ah LIBs. This circumstance can be explained by the intensity of the reactions due to the different battery capacities: In the 5.3 Ah cells a larger amount of unreacted material is immediately discharged from the reaction center, and by the different available amounts of oxidizing reaction partners. An increase of the water content in the surrounding atmosphere during the thermal runaway leads to a reduction of the measurable gas concentrations of up to 36.01%. In general, all measured concentrations decrease. With increased water content more reaction products from the atmosphere can be directly bound or settle as condensate on surfaces.

Short-Circuit Capability Prediction and Failure Mode of Asymmetric and Double Trench SiC MOSFETs

In this article, short-circuit capability prediction and failure mode of 1200-V-class SiC MOSFETs with a double and asymmetric trench structure are proposed under single-pulse short-circuit stress. A short-circuit prediction model is established to evaluate short-circuit withstand time and corresponding critical energy of devices under various dc bus voltages. This model can provide quick predictive guidance even if there are few test results, and the predicted values are consistent with practical values. Furthermore, two failure modes are investigated in a short-circuit test. For asymmetric trench SiC MOSFETs, failure modes are gate damage at lower dc bus voltages and thermal runaway at higher dc bus voltages; whereas failure mode for double trench SiC MOSFETs is thermal runaway at all dc bus voltages. In addition, the internal thermal-electro stress of the device is analyzed until it fails during short-circuit condition, and proves that failure mode depends on the dc bus voltage and peak short-circuit current of the device. Finally, the top view of failed devices confirms the two failure modes of trench SiC MOSFETs by the postdecapsulation.

Fault Detection and Diagnosis Technic Using Electrical Characteristics of a PV Module and Machine Learning Classifier

The growth of photovoltaic power plants is continuously rising, this growth would not be possible without safety, monitoring, and fault detection systems. In this paper, the common faults of a typical photovoltaic power plant that may occur in a photovoltaic module are discussed. Also, the paper studies the electrical characteristics of a photovoltaic module operating under several faults’ conditions applied on a specially designed module that measures the output current of each substring by utilizing sensitive Hall Effect sensors. After obtaining the electrical characteristics under faults, using machine learning, two decision trees classifier models are trained, the first classifier is trained to detect and recognize faults. However, this classifier may confuse the partial shading case with several other faults. Hence, the second decision tree classifier is trained to distinguish the exact fault type when the module is operating under partial shading condition by applying a short-circuit test on the photovoltaic module. This design can be achieved by connecting current sensors in the junction box of a typical photovoltaic module.

Fault Loop Impedance Measurement in Circuits Fed by UPS and Principle of Safety Protection

This paper indicates a significant problem of uncertainty of fault loop impedance (FLI) measurement in circuits powered from uninterruptible power supply (UPS) (double-conversion AC-DC-AC). The correctly determined value of this impedance, related to the short-circuit current disconnection time and to the reference value, is one of the most important elements that determines the approval of an electrical installation and its receivers for operation. To define the principles of FLI measurement, several hundred measurements of the short-circuit loop impedance in the circuits fed by the UPS, in various UPS operation modes and with various FLI instruments, were made, which allowed for the definition of measurement rules that reduce the error in assessing the effectiveness of protection against electric shock by automatic disconnection of supply. Based on the analysis of voltage and current waveforms recorded during the real short-circuit tests in the circuit fed by the UPS, a proprietary algorithm for determining the short-circuit loop impedance has been proposed.

Determination of failure degree of 1.2 kV SiC MOSFETs after short-circuit test using an improved test setup

Abstract Analysis of the short-circuit characteristics of SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) is very important for their practical application. This paper studies the SiC MOSFET short-circuit characteristics with an improved test setup under different conditions. A high-current Si insulated gate bipolar transistor is used as a circuit breaker in the test circuit rather than the usual short-circuit test conducted without a circuit breaker. The test platform with a circuit breaker does not influence the calculation results regarding the short-circuit withstand time and energy, but the SiC MOSFET will switch off after failure in a very short time. In addition, the degree of failure will be limited and confined to a small area, such that the damage to the chip will be clearly observable, which is significant for short-circuit failure analysis.

Problem-Based Learning for an Electrical Machines Course

This article seeks to describe the implementation of a problem-based learning (PBL) teaching-learning method in a university classroom. The aim is for the stu-dent through given real-life situations to acquire knowledge, abilities, and atti-tudes in the subject of electrical machines in the undergraduate electrical engineer-ing program of the Catholic University of Cuenca. Solving problems related to static machines will be similar to the problems that students will face in their pro-fessional lives; namely, to be able to identify a static machine and its operation, parameters, model its equivalent circuits (open- and short-circuit tests), calculate losses, and carry out hysteresis loop measurement. Most of these concepts are abstract and challenging for students to assimilate. Therefore, the present research shows how using the PBL model in studying static machines improves the aca-demic performance and achievement of students in an experimental group. There was an improvement of 7 points out of 100 in relation to the average of the grades of three groups of students from previous semesters. Also, the standard deviation is lower in the experimental group (SD 4.5584), which shows that most of the students improved in their performance. Finally, there was no failure of the study year nor remedial exams among this group.

Combination Technology for Safer Design of Lithium-Ion Batteries

For further penetration of lithium-ion battery, safer battery design with high energy density is required. In the case of the thermal runaway of conventional lithium-ion batteries, the reaction of electrolyte on the surface of graphite anode at higher temperature causes the gas generation with the temperature rise. Subsequently, the short circuit due to the separator meltdown leads to the oxygen release by the pyrolysis of cathode and the thermite reaction above the melting of aluminum utilized for the current collector and the cell package. The construction of novel safer battery systems with high energy density is possible through a judicious choice of each component: cathode material, electrolyte, separator, anode material, current collector and package.We develop safer battery configurations through the analysis of practical batteries using various techniques such as calorimetry and overcharge / internal short-circuit tests. In this study, we assemble 1 Ah class pouch-type full cell with lithium iron phosphate cathode and silicon oxide anode [1]. The full cell shows good charge-discharge properties even at high-rate and 100˚C (Figure 1). On the estimation, however, the electrochemical energy of both electrode active materials is only about 3% of the total thermal energy of full cell. Thus, we replace aluminum with stainless steel utilized for the current collector and package. In addition, we select a separator of heat-stable nonwoven fabric instead of polyethylene/polypropylene. The total thermal energy of full cell by the alternative separator, current collector and package is found to be reduced to 14% of the initial value. In short-circuit testing, the full cell did not show fire though heat and smoke were generated since the maximum temperature of the cell is only 52˚C.In this way, it is possible to design batteries with highly safe by considering the non-flammability of each component such as the current collector and the package as well as the separator.