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AC fault ride through control strategy on inverter side of hybrid HVDC transmission systems

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Journal of Modern Power Systems and Clean Energy 2019年第5期7卷 1129-1141页

作者： Zexin ZHOU Zhengguang CHEN Xingguo WANG Dingxiang DU Guosheng YANG Yizhen WANG Liangliang HAO China Electric Science Research Institute Co. Ltd.BeijingChina State Key Laboratory for Power Grid Safety and Energy Conservation BeijingChina School of Electrical Engineering and Automation Tianjin UniversityTianjinChina College of Electrical Engineering Beijing Jiaotong UniversityBeijingChina

Hybrid high-voltage direct current(HVDC)transmission systems employ a new type of HVDC transmission topology that combines the advantages of the linecommutated converter system and the voltage-source converter system.They can improve the efficiency and reliability of long-distance power transmission.However,realizing alternating-current(AC)grid-fault ride through on the inverter side of a hybrid HVDC transmission system is a challenge considering that a voltage-source converter based HVDC(VSC-HVDC)is used on the inverter side.In this study,a control strategy for an overvoltage fixed trigger angle based on the power-balance method is developed by fully utilizing the operation characteristics of a hybrid HVDC transmission system.The strategy reduces the inverter-side overvoltage of the HVDC system under a fault in the inverter-side AC system.Simulations based on Gezhou Dam are conducted to validate the effectiveness of the proposed strategy.

关键词： Hybrid HVDC transmission fault crossing Control strategy Inverter side

Locally Linear Back-propagation Based Contribution for Nonlinear Process fault Diagnosis

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IEEE/CAA Journal of Automatica Sinica 2020年第3期7卷 764-775页

作者： Jinchuan Qian Li Jiang Zhihuan Song State Key Laboratory of Industrial Control Technology College of Control Science and EngineeringZhejiang UniversityHangzhou 310027China Shanghai Research Institute of Huawei Technology Co. LtdShanghai 200127China

This paper proposes a novel locally linear backpropagation based contribution(LLBBC) for nonlinear process fault diagnosis. As a method based on the deep learning model of auto-encoder(AE), LLBBC can deal with the fault diagnosis problem through extracting nonlinear features. When the on-line fault diagnosis task is in progress, a locally linear model is firstly built at the current fault sample. According to the basic idea of reconstruction based contribution(RBC), the propagation of fault information is described by using back-propagation(BP) algorithm. Then, a contribution index is established to measure the correlation between the variable and the fault, and the final diagnosis result is obtained by searching variables with large contributions. The smearing effect, which is an important factor affecting the performance of fault diagnosis, can be suppressed as well,and the theoretical analysis reveals that the correct diagnosis can be guaranteed by LLBBC. Finally, the feasibility and effectiveness of the proposed method are verified through a nonlinear numerical example and the Tennessee Eastman benchmark process.

关键词： Auto-encoder(AE) deep learning fault diagnosis locally linear model nonlinear process reconstruction based contribution(RBC)

Photovoltaic-based DC microgrid with partial shading and fault tolerance

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 340-349页

作者： Carlos CORREA-BETANZO Hugo CALLEJA Carlos AGUILAR Adolfo R.LOPEZ-NUNEZ Elías RODRIGUEZ Electronics Department National Center for Research and Development of Technology62490 CuernavacaMorelosMexico Electronics Department Technological Institute of Celaya38010 CelayaGuanajuatoMexico

Partial shading is a common problem that affects bus regulation in DC microgrids with several photovoltaic(PV) modules as energy sources, as a result of reduced solar irradiance reaching the modules.The problem can be mitigated by incorporating batteries, but if they are not included, appropriate control strategies must be used. This paper presents a new approach in a PV-based DC microgrid, which provides a high-quality bus voltage regulation in islanding mode, without being affected by partial shading or problems associated with PV module connection and disconnection. The solution proposed herein ensures a proper voltage regulation without being affected by problems such as failures in PV modules or mismatch between them. Besides, it can help to prevent PV partial shade stress by disconnecting the affected modules. A further advantage of the approach is the flexibility to connect more PV modules. The advantages of this approach were verified in a 200 W prototype.

关键词： Photovoltaic Microgrid Partial shading fault Control strategy

Particle Swarm Optimization-Support Vector Machine Model for Machinery fault Diagnoses in High-Voltage Circuit Breakers

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中国机械工程学报：英文版 2020年第1期33卷 104-113页

作者： Xiaofeng Li Shijing Wu Xiaoyong Li Hao Yuan Deng Zhao School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China

According to statistic data,machinery faults contribute to largest proportion of High-voltage circuit breaker failures,and traditional maintenance methods exist some disadvantages for that issue.Therefore,based on the wavelet packet decomposition approach and support vector machines,a new diagnosis model is proposed for such fault diagnoses in this study.The vibration eigenvalue extraction is analyzed through wavelet packet decomposition,and a four-layer support vector machine is constituted as a fault classifier.The Gaussian radial basis function is employed as the kernel function for the classifier.The penalty parameter c and kernel parameterδof the support vector machine are vital for the diagnostic accuracy,and these parameters must be carefully predetermined.Thus,a particle swarm optimizationsupport vector machine model is developed in which the optimal parameters c andδfor the support vector machine in each layer are determined by the particle swarm algorithm.The validity of this fault diagnosis model is determined with a real dataset from the operation experiment.Moreover,comparative investigations of fault diagnosis experiments with a normal support vector machine and a particle swarm optimization back-propagation neural network are also implemented.The results indicate that the proposed fault diagnosis model yields better accuracy and e-ciency than these other models.

关键词： High-voltage circuit breaker Machinery fault diagnosis Wavelet packet decomposition Support vector machine

The design and fault ride through control of un-interrupted DC-DC Autotransformer

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Science China(Technological Sciences) 2018年第12期61卷 1935-1949页

作者： LI MengBo XIANG Wang ZUO WenPing YAO LiangZhong LIN WeiXing WEN JinYu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Renewable Energy Department China Electric Power Research Institute TBEA China Xinjiang Sunoasis Co. Ltd

This paper proposed a novel type of DC-DC converter, termed as un-interrupted DC Autotransformer(un-interrupted DC AUTO), which has the capability to ride through DC fault on either side of the converter without blocking any devices. Besides that, the adequately designed converter retains the advantages of DC AUTO technology, namely reduced investment cost and transmission loss. To begin with, the topology and basic attributes of the un-interrupted DC AUTO are illustrated. Then the design goals and the corresponding design procedures are analyzed. Furthermore, an effective control system is proposed to enable the converter steady operation during both normal and faulted conditions. Finally, a 1000 MW ±320 kV/±640 kV test system is built on PSCAD/EMTDC platform to verify the technical feasibility of the proposed converter and the effectiveness of the control strategy.

关键词： DC-DC power conversion DC Autotransformer HVDC converters DC fault control strategy

Study on the rupture characteristics of the overlaying soil with soft interlayer due to fault bedrock dislocation

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Acta Seismologica Sinica(English Edition) 2006年第5期19卷 563-568页

作者：赵雷李小军霍达 Department of Civil Engineering Beijing University of Technology Institute of Engineering Mechanics China Earthquake Administration Institute of Geophysics China Earthquake AdministrationBeijing 100081China

In this paper, the rupture characteristics of the overlaying soil with soft interlayer were studied by plane-strain finite element method. From the results, it can be shown that the existence of soft layer separates rupture process of the overlaying soil into two phases. The depth of a buried soft interlayer will influence the rupture process and the rupture range of the overlaying soil. The deeply buried soft interlayer would bring about a wider range of surface failure. In addition, the thickness of the soft layer also has effect on the rupture process and rupture range of the overlaying soil.

关键词： fault soft interlayer overlaying soil finite element method

Active fault-tolerant tracking control of a quadrotor with model uncertainties and actuator faults

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Frontiers of Information Technology & Electronic Engineering 2019年第1期20卷 95-106页

作者： Yu-jiang ZHONG Zhi-xiang LIU You-min ZHANG Wei ZHANG Jun-yi ZUO School of Aeronautics Northwestern Polytechnical University Department of Mechanical Industrial and Aerospace Engineering Concordia University

This paper presents a reliable active fault-tolerant tracking control system(AFTTCS) for actuator faults in a quadrotor unmanned aerial vehicle(QUAV). The proposed AFTTCS is designed based on a well-known model reference adaptive control(MRAC) framework that guarantees the global asymptotic stability of a QUAV system. To mitigate the negative impacts of model uncertainties and enhance system robustness, a radial basis function neural network is incorporated into the MRAC scheme for adaptively identifying the model uncertainties online and modifying the reference model. Meanwhile, actuator dynamics are considered to avoid undesirable performance degradation. Furthermore, a fault detection and diagnosis estimator is constructed to diagnose lossof-control-effectiveness faults in actuators. Based on the fault information, a fault compensation term is added to the control law to compensate for the adverse effects of actuator faults. Simulation results show that the proposed AFTTCS enables the QUAV to track the desired reference commands in the absence/presence of actuator faults with satisfactory performance.

关键词： Model reference adaptive control Neural network Quadrotor fault-tolerant control fault detection and diagnosis

A fault locating method for multi-branch hybrid transmission lines in wind farm based on redundancy parameter estimation

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Journal of Modern Power Systems and Clean Energy 2019年第5期7卷 1033-1043页

作者： Ke ZHANG Yongli ZHU Xuechun LIU State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University) Baoding 071003China State Grid Wuxi Power Supply Company Wuxi 214000China

In order to solve the problem of‘‘abandoned’’wind caused by short circuit faults in a wind farm,a wind farm fault locating method based on redundancy parameter estimation is proposed.Using the characteristics of the traveling wave,transmission equations containing the position of the fault point are constructed.Parameter estimation from statistical theory is used to solve the redundant transmission equations formed by multiple measuring points to locate the faults.In addition,the bad data error detection capability of the parameter estimation is used to determine bad data and remove them.This improves locating accuracy.A length coefficient is introduced to solve the error enlargement problem caused by a transmission line sag.The proposed fault locating method can solve the fault branch misjudgment problem caused by the short-circuit faults near the data measuring nodes of thewind farm based on the proposed fault interval criterion.It also avoids the requirements to the traveling wave speed of traditional methods,thus its fault location is more accurate.Its effectiveness is verified through simulations in PSCAD/EMTDC,and the results show that it can be used in thefault locating of hybrid transmission lines.

关键词： Transmission line fault location method Parameter estimation Wind power Least squares

Robust fault estimation for uncertain switched linear systems with time-varying delay

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Journal of Central South University 2015年第11期22卷 4254-4262页

作者：钟燕科陈特放陈春阳 School of Information Science and Engineering Central South University School of Electrical and Electronic Engineering East China Jiaotong University

The problem of fault estimation is investigated for a class of uncertain switched systems with time-varying delay. A robust observer-based fault estimator is designed such that the augment error system is exponentially stable and the H∞ performance index meets the predefined requirements. Based on the multiple Lyapunov-Krasovskii functions and the average dwell-time method, the delay dependent sufficient conditions on the existence of desired fault estimator are established. However, since these conditions are not linear matrix inequalities(LMIS), they can not be solved by MATLAB. By using a novel method, these conditions are presented in terms of LMIS. Finally, a numerical example is carried out. The designed fault estimator could tract the fault signal timely. Besides, the error between estimation and fault is very small. Therefore, the validity of the obtained results is illustrated.

关键词： fault estimation switched linear system time-varyi