Common Electrical Faults Research Articles

Diagnosis and Identification of Common Electrical Faults in PM Machine Drives

Diagnosis and Identification of Common Electrical Faults in PM Machine Drives

Effect of Cooling Pump Transient Power Supply on ETRR-2 Safety Parameters

The primary goals of the engineering design for nuclear reactors involve safeguarding the integrity of the reactor core. Preserving the integrity of the cladding material is especially crucial, as it serves as the initial defense against the potential dangers posed by radioactive materials. In this work, an accident analysis of core cooling pump power transients of different ratios of the nominal pump power in a typical material test reactor is conducted. Phase failure is a very common electrical fault experienced by three-phase motors. Pump power reduction can be initiated due to several causes, like phase failure, voltage reduction, winding failure, and other causes. The nuclear reactor analysis code PARET/ANL version 7.6 is used to carry out these calculations. The accident scenario began with the reactor operating steadily, then experiencing a transient in the core pump power. This caused the core flow rate to decrease and eventually stabilize at a lower level as the pump power decreased. Core cooling pump power variations ratios of 20%, 33.3%, 50%, and 70% of the nominal pump power are considered in this work. The accident analysis is conducted under the availability and unavailability of reactor safety systems. Reactor safety parameters are reported for all cases of the core pump power variations.

A Search Coil Design Method of PMSM for Detection of Inter-Turn Short-Circuit Fault

Fault diagnosis systems based on search coils are widely used for detecting the inter-turn short-circuit (ITSC) fault, which is one of the most common electrical faults in electrical machines. Although various search coil structures have been proposed, there is not a systematic method proposed for the design of search coils. In addition, there is not a quantitative evaluation standard to evaluate the performances of search coils in each aspect, making it difficult to judge whether the proposed search coil structure is the optimal one. In this paper, the reliability, sensitivity and positioning ability of search coils are derived and evaluated by four defined characteristic indexes. And based on these four characteristic indexes, a systematic search coil design method based on the mutual inductance matrix is also proposed. With the proposed design method, the optimal search coil structures for different permanent magnet synchronous machines (PMSMs) are designed and optimized. It is found that the search coils designed by the proposed method have good performance in reliability, sensitivity and positioning ability. The performances of designed search coils are validated by the finite element analysis (FEA) and experiment.

Fault diagnosis of building electrical system based on compressed perception theory

Building electrical systems in modern buildings are increasingly playing a pivotal role in bringing people the convenience of life, at the same time, the building electrical system will inevitably fail. And the research of intelligent fault diagnosis algorithms for this field is still in its infancy. At this stage, the accuracy and reliability of fault monitoring and diagnosis of most building electrical systems are yet to be improved. Aiming at the current lack of effective diagnosis of faults in the building electrical system, this paper takes the fault situation of the electrical system in the building as the main object of research, and simulates the common building electrical faults through the comprehensive experimental platform of the building electrical, taking into account the problem of low diagnostic efficiency of the building electrical system. This paper puts forward a fault diagnostic algorithm based on the combination of compressed perception and the K-nearest neighbor algorithm, which is aimed at improving the diagnostic efficiency of building electrical system faults. The results show that the proposed fault diagnosis algorithm can not only improve the accuracy of fault classification but also shorten the time of fault classification, which greatly improves the fault diagnosis efficiency.

A Novel Diagnosis Strategy for Switches With Common Electrical Faults in Modular Multi-Level Half-Bridge Energy Storage Converter

A Novel Diagnosis Strategy for Switches With Common Electrical Faults in Modular Multi-Level Half-Bridge Energy Storage Converter

Research on fault adaptive fault tolerant control of distributed wind solar hybrid generator

Due to the poor accessibility, poor operating conditions, high failure rate, long maintenance time, and difficult maintenance of wind hybrid generators, the economic loss is huge once the failure stops. To this end, the fault adaptive fault-tolerant control of distributed wind and wind hybrid generators is studied, the historical operation data of offshore wind and wind hybrid generators and onshore wind and wind hybrid generators are counted and compared, and the fault characteristics of key components of offshore wind and wind hybrid generators are analyzed. The generator sets are summarized, and the common electrical faults of wind turbines and their impacts on the system are analyzed. This paper summarizes the current research status of fault-tolerant operation of existing offshore wind and wind complementary generators in terms of software fault tolerance and hardware fault tolerance, summarizes the current fault tolerance schemes for offshore wind and wind complementary generators, and analyzes the application feasibility of existing fault tolerance schemes. In addition, the main problems of fault-tolerant offshore wind and solar complementary generator sets are pointed out, and future research hotspots are foreseen.

Detection and Evaluation of the Interturn Short Circuit Fault in a BLDC-Based Hub Motor

A brushless dc (BLDC) motor with an outer rotor has great potential for emerging electric vehicle (EV) applications as an in-wheel hub motor. Interturn short circuit faults (ISCFs) are common electrical faults in these applications, and their fault diagnosis is of critical importance. This article proposes a signal analysis-based method to detect and quantitatively analyze the ISCF in a BLDC motor under a six-step commutation control strategy. The zero-sequence voltage component (ZSVC) and three-phase currents are simultaneously determined while the fundamental frequency amplitude of the ZSVC is developed as a fault indicator for diagnostic purposes. Thereafter, the faulty phase is identified, and the fault severity is estimated by jointly analyzing the ZSVC and faulted phase current. The proposed technique entails creating an analytical model, a simulation model, and experimental tests. Experimental results demonstrate that the proposed technique has excellent accuracy, quick response, and real-time fault diagnosis for BLDC motors. This technique will accelerate the use of BLDC-based hub motors in EVs and the widespread application of EVs to reduce the carbon emissions.

An Online Multifault Diagnosis Scheme for Battery Packs Based on Voltage Envelope Relationship

Electrical faults pose a serious threat to the safe operation of battery packs. Common electrical faults include undervoltage, overvoltage, connection faults, and sensor faults. However, existing methods fail to provide a comprehensive and adequate diagnosis of the four types of electrical faults due to their inability to distinguish between fault signatures. This article proposes an online multifault diagnosis scheme based on voltage envelopes. First, using the positive and negative envelopes of voltages, unique fault signatures are constructed for each type of electrical fault, where the similarity and polarity of the envelopes are selected as indicators. Then, an improved Hausdorff distance and a cross-voltage measurement circuit are employed to catch the fault signatures. By comparing the similarity and polarity between the adjacent envelopes, four types of faults can be detected and sequentially distinguished. Finally, an online diagnosis flow is designed, where normalization and the Douglas–Peucker algorithm are used to ensure robustness to inconsistency and noise. Experimental results show that the four types of faults can be accurately diagnosed within a short period of time, and a minor fault characterized by a 0.07-C discharge current can still be sensitively detected. In addition, the inconsistency and noise within the normal range cannot cause a misdiagnosis.

Double Line-to-Ground Faults Detection Method in DC-AC Converters

Numerous electrical machines use power converters for their efficient operation. However, their insulations experience a fast deterioration due to high frequency electrical stresses. This loss of insulation can lead into ground faults, which are the most common electrical faults. Convectional protection relays are not specifically designed to protect electrical drives. Moreover, relays’ malfunction could be provoked because of commutation noises, or DC and AC fault current's components influence in their measurement. Therefore, if the fault is not detected in time, it can be developed into a more severe fault. This paper proposes a detection method for high resistance double line-to-ground faults in electrical drives based on a grounding resistor placed in the midpoint of the DC side. The method has been developed for DC/AC systems and it is based on the voltage measurement in the grounding resistor and in the AC phases. Afterwards, performing a frequency domain analysis of the grounding resistor voltage and comparing its fundamental harmonic phase differences with the AC voltage phasors, the double line-to-ground fault incipient zone (DC and/or AC) can be detected, and also, the DC faulty pole or AC faulty phase can be discerned. The method has been verified through computer numerous simulations and experimental tests in a 140 kW power converter, obtaining satisfactory results in the fault detection. However, the exact location of each ground fault still being incognita.

Current Prediction-Based Fast Diagnosis of Electrical Faults in PMSM Drives

Open-phase fault (OPF) and open-switch fault (OSF) are two common electrical faults in the permanent magnet synchronous machine (PMSM) drives. To locate the faults rapidly and relieve the fault damage, a current prediction-based diagnosis scheme is proposed for OPF and OSF in three-phase PMSM drives. The proposed diagnosis scheme consists of three steps, namely, determining fault occurrence, locating the faulty phase, and identifying the specific fault. The general current deviations between dq-axis predicted currents from the normal model and dq-axis feedback currents are used to determine the fault occurrence. The general current deviations between dq-axis feedback currents and dq-axis predicted currents from different faulty models are used to locate the faulty phase. Then, an intervention-based diagnosis is developed to identify the specific fault. In this way, the specific fault can be quickly located within several switching periods. Finally, the effectiveness of the proposed diagnosis scheme is verified by the experimental results.

On-line fault diagnosis and fault-tolerant operation of modular multilevel converters — A comprehensive review

Modular multilevel converters (MMCs) have been one of the most broadly used multilevel converter topologies in industrial applications, particularly in medium-voltage motor drives and high-voltage dc power conversion systems. However, due to the utilization of large amount of semiconductor devices, the reliability of MMCs becomes one of the severe challenges constraining their further development and applications. In this paper, common electrical faults of the MMC have been summarized and analyzed, including open-circuit switching faults, short-circuit switching faults, dc-bus short-circuit faults, and single line-to-ground faults on the ac side. A thorough and comprehensive review of the existing online fault diagnostic methods has been conducted. In addition, fault-tolerant operation strategies for such various fault scenarios in MMCs have been presented. All the fault diagnosis and fault-tolerant operation strategies are comparatively evaluated, which aims to provide a state-of-the-art reference on the MMC reliability for future research and industrial applications.

Fault-Tolerant Control of Common Electrical Faults in Dual Three-Phase PMSM Drives Fed by T-Type Three-Level Inverters

In this article, a deadbeat predictive current control based fault-tolerant control scheme is proposed for common electrical faults in T-type three-level inverter-fed dual three-phase permanent magnet synchronous machine (PMSM) drives, which aims at providing a solution for the application of high power rating, low switching frequency, low complexity, and high reliability. First, deadbeat control is combined with current prediction to obtain precise voltage reference for the current control. Each three-phase three-level inverter generates a single optimal inverter voltage vector based on a new division method of space vector diagram. In this way, both low switch frequency and high control precision can be guaranteed in a high-power motor system. Second, fault-tolerant control schemes are designed for five types of common electric faults in a T-type three-level inverter-fed dual three-phase PMSM without changing the mathematical model and control framework. Thus, the complexity of the proposed fault-tolerant control schemes can be avoided and smooth transition can be guaranteed. The validity of the proposed schemes is verified by experimental results.

Radial Force Minimization Control for Fault-Tolerant Switched Reluctance Machines With Distributed Inverters

Switched reluctance machines (SRMs) are known for their simple and robust mechanical design, low magnetic pole, and phase coupling as well as low short-circuit current and open-circuit voltage during a fault condition. These advantages make the SRM a suitable candidate for applications, which requires high-reliability and fault-tolerant operation. This article addresses the challenge of minimizing the unbalanced magnetic pull (UMP) caused during a single-pole failure, which is the most common electrical fault found in SRMs. In fault-tolerant SRMs, usually, the entire faulty phase is turned off to continue operation. To minimize the loss of torque production during a fault, a distributed inverter (one inverter module per coil) is introduced enabling the SRM to continue operation with all remaining healthy poles. Furthermore, a fault-tolerant control strategy utilizing the advantages of the distributed inverter, namely, radial force minimization control (RFMC), is proposed. This control allows a considerable reduction in the UMP while maintaining constant torque control during faulty operation. A four-phase 1-kW 16/12 SRM with a distributed inverter is used to present the theoretical approach and simulation results of the proposed control algorithm. Furthermore, experimental measurement results for the RFMC are shown to validate the effectiveness of the introduced algorithm.

Research on the Fault Characteristic of Wind Turbine Generator System Considering the Spatiotemporal Distribution of the Actual Wind Speed

A reliable fault monitoring system is one of the conditions that must be considered in the design of large wind farms today. The most important factor for the fault monitoring should be the accurate diagnosis criteria with sensitive fault characteristics. Most of the current fault diagnosis criteria are obtained based on the average wind speed at the center of the hub which is not in accord with the actual wind condition in nature. So, this paper utilizes an equivalent wind speed (EWS), which can describe the actual wind speed spatiotemporal distribution on the rotor disk area considering the effects of wind shear and tower shadow, to analyze the common mechanical and electrical faults again. Firstly, the EWS model applicable to the 3-blade wind turbines is introduced; then the new fault characteristics of the wind turbine rotor aerodynamic imbalance and the stator winding asymmetry are theoretically analyzed based on the EWS model; finally, the simulation platform is built in Matlab/Simulink for comparison and the simulation result is well consistent with the theory analysis. The aim of this research is to find more accurate fault characteristics and help promoting the healthy development of wind power industry.

Research and Application of Generator Protection Based on Fiber Optical Current Transformer

This paper introduces the basic principle of fibre optical current transformer (FOCT), and explains the advantages of FOCT compared with electromagnetic current transformer (CT). FOCT can be wound around the primary conductor in any shape, has high harmonic accuracy and doesn't suffer from saturation, thus a good solution for generator relay protection. As a common electrical fault within large generators, the inter-turn short circuit in field windings (ISCFW) is likely to cause earth faults between the field winding and the rotor body and magnetization of the main shaft without timely intervention. Steady-state unbalanced currents of even orders and fractional orders related with pole pairs inside phase windings are required to monitor the ISCFW. The inter-turn fault of stator windings may rapidly develop into a phase to phase fault, which seriously threatens the safety of the unit. Split-phase transverse differential current reflects the steady-state current imbalance inside the stator winding. Nevertheless, for most steam turbine generators and some hydro turbine generators, it is unable to obtain phase-segregated transverse differential current due to impossibility of installing branch current transformer in the narrow space inside the generator. However, FOCT which uses fibre optic cable as a sensor is installable within limited space to measure the current of each group of winding branches of each phase. FOCT furthers phase-segregated transverse differential protection, partial differential protection and online monitoring of the ISCFW, thus optimizing the generators protection scheme. In addition, operating speed and sensitivity of generator differential protection are improved based on the reliable measurement from FOCT. The proposed scheme is verified by an application on a 300MW generator at a pump-storage power plant. This is the first attempt of applying FOCT to the relay protection of generator set, which provides reference for further development and application of FOCT in power plant.

Diagnosis and Tolerance of Common Electrical Faults in T-Type Three-Level Inverters Fed Dual Three-Phase PMSM Drives

In this paper, diagnosis and tolerant control schemes have been studied for common electrical faults in T-type three-level inverter fed dual-three phase permanent magnet synchronous motor (PMSM) drives for safety-critical applications. Based on vector space decomposition and double three-phase space vector modulation, diagnostic and tolerant control methods have been developed comprehensively for open-phase faults, open-switch faults, and short-switch faults in T-type three-level inverter fed dual-three-phase PMSM drives, in such way that misdiagnosis of different faults sharing similar faulty features can be avoided. In particular, a two-step diagnostic scheme is proposed in order to simplify the diagnostic process. The first step is to identify the faulty phase and fault category by analyzing current trajectories on harmonic subspace, and the second step is to determine the specific fault type in a small fault-searching area obtained from the first step. In the aspect of fault-tolerant control, a novel current compensation method is proposed for open-phase fault without changing the machine model, space vector diagram, and control framework. Open-switch faults and short-switch faults are tolerated by making full use of the remaining vectors after faults. The validity of the proposed fault diagnosis and tolerance schemes has been verified by experiments.

Structure of Tunnel Digging and Loading Trolley and Calculation of Electronic Control System and Analysis of Common Faults of Electronic Control

The tunneling truck is mainly used for tunneling construction. It has the functions of digging, loading, anchoring, and wet spraying.This paper analyses the main structure and working principle of tunnel digging and loading trolley, the selection and calculation of main electrical components, the overall calculation of tunnel digging and loading trolley, and the common electrical faults and troubleshooting methods. It has certain reference value for domestic counterparts.

Research on Vector Control Strategy of Surface-mounted Permanent Magnet Synchronous Machine Drive System with High-Resistance Connection

High-resistance connection (HRC) is a common electrical fault for the electric machine drive system. This fault can lead to the increased power loss and heat, thus possibly causing the damage of the electric machine drive system due to the excessive temperature. Hence, this paper first proposes a vector control strategy of the surface-mounted permanent magnet synchronous machine (PMSM) drive system with the HRC fault to minimize the copper loss. The mathematical model of the PMSM with the HRC is presented in abc stationary frame. The function relationship between the copper loss and the direct axis current, quadrature axis current, stator resistance, and the additional resistance due to the HRC is established and analyzed. The expression of the direct axis current, which minimizes the copper loss, is deduced under the condition of the HRC in one phase and two phases. Consequently, the proposed vector control strategy for the surface-mounted PMSM driving system is achieved. Both the simulation and experimental results show that the proposed method not only preserves the performance of the conventional vector control method, but also can effectively reduce the copper loss, thus protecting the PMSM from the damage due to the increased temperature possibly caused by the HRC fault.

An Online Diagnostic Method for Rotary Diode Open-Circuit Faults in Brushless Exciters

A rotating diode failure is the most common electrical fault in brushless exciters. It brings a safety hazard to the generator excitation system so that the whole unit is forced to be shut down. It is necessary to detect and deal with this fault accurately. According to the electrical structure characteristics of brushless exciters, this paper analyzes the influence of an open circuit rotating diode on the armature current and armature magnetic field. It is proposed here that we install the magnetic field detection coil on the stator yoke and use the rotational frequency component in the induced voltage to diagnose the open circuit fault in the rotating diode online. In this paper, a two-dimensional model of a 22-pole 39-phase brushless exciter is established, and the new detection method is verified using a finite element simulation. This provides a new solution for rotating diode fault diagnosis in brushless exciters. The detection method exhibits good performance in terms of practicability, real-time usage, and versatility.

A Statistical Analysis of Electrical Faults in the LHC Superconducting Magnets and Circuits

The large hadron collider (LHC) at CERN has been operating and generating physics experimental data since September 2008, and following its first long shut down, it has entered a second, 4-year-long physics run. It is to date the largest superconducting installation ever built, counting over 9000 magnets along its 27-km long circumference. A significant operational experience has been accumulated, including the occurrence and consequences of electrical faults at the level of the superconducting magnets, as well as their protection and instrumentation circuits. The purpose of this paper is to provide a first overview of the most common electrical faults and their frequency of occurrence in the first years of operation, and to perform a statistical analysis that can provide reference values for future productions of similar dimensions and nature.