Research on Inter-turn Short-circuit Fault Diagnosis Method Based on High Frequency Voltage Residual for PMSM

Inter-turn fault is a serious stator winding short-circuit fault of permanent magnet synchronous machine(PMSM). Once it occurs, it produces a huge short-circuit current that poses a great risk to the safe operation of PMSM. Thus, an inter-turn short-circuit fault(ITSCF) diagnosis method based on high frequency(HF) voltage residual is proposed in this paper with proper HF signal injection. First, the analytical models of PMSM after the ITSCF are deduced. Based on the model, the voltage residual at low frequency(LF) and HF can be obtained. It is revealed that the HF voltage residual has a stronger ITSCF detection capability compared to the LF voltage residual. To obtain optimal fault signature, a 3-phase symmetrical HF voltage is injected into the machine drive system, and the HF voltage residuals are extracted. The fault indicator is defined as the standard deviation of the 3-phase HF voltage residuals. The effectiveness of the proposed ITSCF diagnosis method is verified by experiments on a triple 3-phase PMSM. It is worth noting that no extra hardware equipment is required to implement the proposed method.

Analysis on the fault characteristics of three-phase short-circuit for half-wavelength AC transmission lines

Half-wavelength AC transmission(HWACT) is an ultra-long distance AC transmission technology, whose electrical distance is close to half-wavelength at the system power frequency. It is very important for the construction and operation of HWACT to analyze its fault features and corresponding protection technology. In this paper, the steady-state voltage and current characteristics of the bus bar and fault point and the steady-state overvoltage distribution along the line will be analyzed when a three-phase symmetrical short-circuit fault occurs on an HWACT line. On this basis, the threephase fault characteristics for longer transmission lines are also studied.

Short-circuit fault analysis and isolation strategy for matrix converters

The behavior of matrix converter(MC) drive systems under the condition of MC short-circuit faults is comprehensively investigated. Two isolation strategies using semiconductors and high speed fuses(HSFs) for MC short-circuit faults are examined and their performances are compared. The behavior of MC drive systems during the fuse action time under different operating conditions is explored. The feasibility of fault-tolerant operation during the fuse action time is also studied. The basic selection laws for the HSFs and the requirements for the passive components of the MC drive system from the point view of short-circuit faults are also discussed. Simulation results are used to demonstrate the feasibility of the proposed isolation strategies.

Remedial Phase-Angle Control of a Five-Phase Fault-Tolerant Permanent- Magnet Vernier Machine With Short-Circuit Fault

A fault-tolerant permanent-magnet vernier(FT-PMV)machine incorporates the merits of high fault-tolerant capability and high torque density.In this paper,a remedial phase-angle control(RPAC)strategy is proposed for a five-phase FT-PMV machine with short-circuit fault.Firstly,the proposed strategy can reduce the amount of unknown quantities by structuring the phase-angles of the normal phases.It can simplify the calculation of the remedial currents.Then,in order to obtain the desired torque,only the amplitudes of the remedial currents need to be calculated.Based on the principle of instantaneous electrical input power and mechanical output power balance condition,the real components are used to maintain the torque capability,while the reactive components are limited zero to minimize the torque ripple.Both simulations and experiments are presented to verify the proposed RPAC strategy.

分布式静止串联补偿器相间协调控制方法

分布式静止串联补偿器(DSSC)是一种串联型分布式柔性交流输电装置,功率模组串联接入交流线路。为快速、平稳地处理DSSC的各相模组故障,本文提出相间协调控制策略,通过引入热备用控制机制,在三相DSSC的某一相出现模组故障后,将非故障相指定模组转为热备用状态并输出零电压,同时提升各相正常模组的输出电压,从而保持DSSC输出总电压不变,在避免对交流电网造成不平衡扰动的同时,保证模组故障不影响线路稳态潮流。在湖州分布式潮流控制器(DPFC)示范工程中,通过开展模组故障模拟试验,验证了相间协调控制方法的可行性和有效性。

多通道电流信号深度特征融合的开关磁阻电机故障诊断研究

提出一种基于卷积神经网络(convolution neural networks,CNN)与Transformer结合的新型深度学习框架1D-Uniformer(one dimensional unified transformer),解决开关磁阻电机高阻接触故障和相间短路故障的分类识别问题。搭建开关磁阻电机故障诊断实验平台,在开关磁阻电机定子绕组上设置高阻接触故障和相间短路故障,并通过非侵入式方法采集电机的三相电流信号;引入动态位置嵌入、多头关系聚合器和前馈网络对传统CNN进行改进,得到1D-Uniformer以充分提取高阻接触故障和相间短路故障的特征。实验结果表明:该模型在高阻接触故障和相间短路故障诊断方面均具有很好的分类效果,在18种故障状态下识别精度能达到100%,在不同的噪声强度下仍然具有较高的鲁棒性。

电力线路相间故障的继电保护研究

交流过电流继电器和瞬时过电流继电保护是电网系统最常用的继电保护,用于防止高压电力线路中的相间故障。该保护装置也用于防止电源变压器的外部短路故障。目前,对于电力供应的连续性和安全性要求不断提高,所以,对继电保护装置的性能、选择性和灵敏度的要求也增加,电力系统元件继电保护整定的协调对电网系统的正常运行具有重要意义。文章研究最常用的导体截面的电缆线路和16MVA、25MVA、31.5MVA和40MVA的电力变压器的相间故障继电保护设置的协调。

输电线路相间故障引发直流双极换相失败分析

对一起220 kV交流线路相间故障引发直流双极换相失败的原因开展了分析,分析结果表明,220 kV线路AB相故障后,直流换流站500 kV交流母线电压遭受扰动,主要表现为故障相电压幅值跌落、换相电压过零点偏移,二者叠加引发了直流换相失败。并且,作为实际工程中预防换相失败的主要手段,换相失败预测控制在所提事件中未能及时识别故障,对于第一次换相失败并未起到预防作用。此外,换相失败受故障时刻等偶然因素与控制响应的复杂交互影响,所提事件中,正常的换相过程后紧跟换相失败,无过渡换相过程可供控制参考调节,情况较为不利。最后,结合所提事故案例,针对换相失败分析与抑制提出了相关建议。

Design and Optimization of Dual-Winding Fault-Tolerant Permanent Magnet Motor

To improve the performance of the traditional fault-tolerant permanent magnet(PM)motor,the design and optimal schemes of dual-winding fault-tolerant permanent magnet motor(DWFT-PMM)are proposed and investigated.In order to obtain small cogging torque ripple and inhibiting the short-circuit current,the air gap surface shape of the PM and the anti short-circuits reactance parameters are designed and optimized.According to the actual design requirements of an aircraft electrical actuation system,the parameters,finite element analysis and experimental verification of the DWFT-PMM after optimal design are presented.The research results show that the optimized DWFT-PMM owns the merits of strong magnetic isolation,physics isolation,inhibiting the short circuit current,small cogging torque ripple and high fault tolerance.

Placement optimization of Multi-Type fault current limiters based on genetic algorithm

The fault current limiter(FCL)is an effective measure for improving system stability and suppressing short-circuit fault current.Because of space and economic costs,the optimum placement of FCLs is vital in industrial applications.In this study,two objectives with the same dimensional measurement unit,namely,the total capital investment cost of FCLs and circuit breaker loss related to short-circuit currents,are considered.The circuit breaker loss model is developed based on the attenuation rule of the circuit breaker service life.The circuit breaker loss is used to quantify the current-limiting effect to avoid the problem of weight selection in a multi-objective problem.The IEEE 10-generator 39-bus system in New England is used to evaluate the performance of the proposed genetic algorithm(GA)method.Comparative and sensitivity analyses are performed.The results of the optimized plan are validated through simulations,indicating the significant potential of the GA for such optimization.

Single-phase earth fault current distribution between optical fiber composite overhead ground wire and ordinary ground wire in transmission system

It is important for the safety of transmission system to accurately calculate single-phase earth fault current distribution.Features of double sided elimination method were illustrated.Quantitative calculation of single-phase earth fault current distribution and case verification were accomplished by using the loop method.Influences of some factors,such as single-phase earth fault location and ground resistance of poles,on short-circuit current distribution were discussed.Results show that:1) results of the loop method conform to those of double sided elimination method;2) the fault location hardly influences macro-distribution of short-circuit current.However,current near fault location is evidently influenced;and 3) the short-circuit current distribution is not so sensitive to the ground resistance of poles.

New “Intellectual Networks” (Smart Grid) for Detecting Electrical Equipment Faults, Defects and Weaknesses

The most important elements of “intellectual networks” (Smart Grid) are the systems of monitoring the parameters of electrical equipment. Information-measuring systems (IMS), which described in this paper, were proposed to use together with rapid digital protection against short-circuit regimes in transformer windings. This paper presents an application’s experience of LVI-testing, some results of the use of Frequency Response Analysis (FRA) to check the condition of transformer windings and infra-red control results of electrical equipment. The LVI method and short-circuit inductive reactance measurements are sensitive for detecting such faults as radial, axial winding deformations, a twisting of low-voltage or regulating winding, a losing of winding’s pressing and others.

Intelligent System Design for Stator Windings Faults Diagnosis:Suitable for Maintenance Work

The short circuit is a severe fault that occurs in the stator windings. Therefore, it is very important to diagnose this type of failure in its beginning before it causes unscheduled stop and the machine loss. In this context, the Support Vector Machine (SVM) is a tool of considerable importance for standard classification. From some training data, it can diagnose whether or not there is a short circuit beginning, and which is important for predictive maintenance. This work proposes a technique for early detection of a short circuit between the turns aiming at its implementation in a real plant. The paper shows simulation and experimental results, and validates the proposed technique.

Validation of Full-Converter Wind Power Plant Generic Model Based on Actual Fault Ride-Through Measurements

Modeling and validation of full power converter wind turbine models with field measurement data are rarely reported in papers. In this paper an aggregated generic dynamic model of the wind farm consisting of full power converter wind turbines is composed and the model validation based on actual field measurements is performed. The paper is based on the measurements obtained from the real short circuit test applied to connection point of observed wind farm. The presented approach for validating the composed model and fault ride-through （FRT） capability for the whole wind park is unique in overall practice and its significance and importance is described and analyzed.

利用多次扰动电流波形特征的配电网相间永久故障识别方法

针对配电网相间故障后自动重合闸盲目重合于永久性故障的问题,提出一种利用多次扰动电流波形特征的配电网相间重合前永久故障识别方法。配电线路相间故障三相跳闸后,依次对3个相间回路施加高频电压扰动。永久故障时故障相间回路、非故障相间回路均包含过渡电阻支路,而瞬时故障熄弧后即无故障时各相间回路均不受过渡电阻支路影响,永久故障和瞬时故障时对应的相间回路扰动电流的波形存在显著差异,利用该差异进行相间回路状态甄别。进一步利用Hausdorff距离系数H表征扰动电流波形的差异,若在判别周期内多次扰动电流的波形高度一致,即H值接近于0,则判为相间永久性故障。并构造了基于Hausdorff距离系数的永久故障识别判据和实现方案。PSCAD/EMTDC仿真计算与实验验证结果表明,该方法可有效判别永久性故障,并且基本不受过渡电阻、故障位置的影响。

继电保护与配电自动化协同故障处理技术

本研究主要探究了继电保护与配电自动化协同故障处理技术在相间短路故障与小电流接地故障中的应用。文章首先介绍了相间短路故障、小电流接地故障的处理思路、保护配置和整定方案。随后设计了对照处理,原方案为“继电保护+电压时间型馈线自动化处理”,新方案为“继电保护+配电自动化协同处理”,验证两种方案对相间短路故障、相电流接地故障的处理效果。结果表明,运用新方案处理相间短路故障,停电户数和长时间停电户时数均有明显下降;运用新方案处理小电流接地故障,年均短时停电户次数减少了85.4%。继电保护与配电自动化协同处理技术对相间短路故障和小电流接地故障的处理效果良好。

配网大档距裸导线风偏技术探讨

文章对安徽省内典型风带、配网裸导线大档距现状、架空线路风偏故障原因做了简要分析,对大档距裸导线风偏故障的防范治理措施,从绝缘化、缩档距、增相距、强运维共4个方面,阐述了具体可行的技术方案,共同探讨。

主动扰动技术在停电配电线路相间故障检测中的应用

提出了一种停电中压配电线路相间故障检测技术。在配电变压器低压侧经电力电子开关接入一逆变电源,馈线停电后,通过控制电力电子开关将逆变电源经配电变压器短时接入,在给停电线路故障相间施加瞬时高压以击穿可能存在的故障点的同时,通过对断路器下游侧暂态电压的检测与分析判定是否存在相间故障。该技术无需通信,既可用于配电线路自适应重合闸,也可用于停电一段时间后的尝试性送电,理论、仿真分析和模拟实验均验证了所提技术的有效性。

配电自动化主站的容错故障定位方法

为了提高配电网的故障处理性能,建议采用多重化配置反映开关状态的辅助接点和"三取二"原则以提高开关状态信息采集的容错性能的方法。论述了一种利用电气量的关联关系实现开关状态容错的方法,以及可以应用于中压配电网相间短路故障定位、单相接地故障定位以及基于故障投诉信息的低压配电网故障研判中的基于贝叶斯法的容错故障定位方法。并给出了在单相接地定位中的应用例子,分析结果表明所建议方法具有可行性和有效性。

基于小波变换和强跟踪滤波器的配电网短路故障定位

针对配电线路故障测距受过渡电阻的影响问题,提出强跟踪滤波器的方法实现配电网相间短路故障测距。利用小波分析对配电线路首端故障电流和电压进行预处理,消除信号中的高频噪声信号。分析配电网相间短路构成的故障回路,建立关于线路故障电流和短路过渡电阻的微分方程。合理选择状态量和输出量将故障回路的微分方程转化为状态估计方程,利用强跟踪滤波器的状态估计算法实现相间短路的故障测距。通过Matlab仿真表明该算法是有效的,利用小波分析对故障电流和电压进行处理,能提高测距的快速性和准确性。