Zheng Jianyong

Development and Application of Distributed Multilayer On-line Monitoring System for High Voltage Vacuum Circuit Breaker

On-line monitoring system is important for high voltage vacuum circuit breakers (HVCBs) in operation condition assessment and fault diagnosis. A distributed multilayer system with client/server architecture is developed on rated voltage 10kV HVCB with spring operating mechanism. It can collect data when HVCB switches, calculate the necessary parameters, show the operation conditions and provide abundant information for fault diagnosis. Ensemble empirical mode decomposition (EEMD) is used to detect the singular point which is regarded as the contact moment. This method has been applied to on-line monitoring system successfully and its satisfactory effect has been proved through experiments. SVM and FCM are both effective methods for fault diagnosis. A combinative algorithm is designed to judge the faults of HVCBs operating mechanism. The systems precision and stability are confirmed by field tests.

Real-time measurement of communication subsystem of intelligent electronic devices

IEC 61850 defines two types of specific communication service mapping (SCSM) for sampled values communication among intelligent electronic devices (IED): sampled values over serial unidirectional multi-drop point to point link in IEC 61850-9-1and sampled values over ISO/IEC 8802-3 in IEC 62850-9-2. In view of the importance of real-time communication, packet transfer model was built following IEC 61850, the measurement and calibration method of processing delay for electronic transformer were designed, and the maximum packet transfer delay by queuing theory was calculated. The relevant theoretical analysis and simulation results indicate that the delay of sampled values message could be compensated and its affection on real-time communication of IED could be improved by adopting appropriate network topology.

Application of Saber's simulation model IGBT1 in solid-state switch design

The Saber is the most powerful simulator in the power electronics field of the world. This paper introduces the characteristics of the IGBT1 model and choice of the parameters under Saber, and explains the characteristic of the model to a kind of DC solid-state switch. Through calculating and analyzing the theory of IGBT working course, and simulating the IGBT1 model in the stable and transient process, this paper partially verifies the accuracy of IGBT1 model in stable and transient process and offers reliable assurance for the power electronics simulation

An Improved switched-inductor quasi-Z-source inverter

This paper has presented an improved switched-inductor quasi-Z-source inverter (SL-qZSI). Compared with the classic SL-qZSI, the boost ability of proposed topology is significantly strengthened. The operation principle of the proposed topology is analyzed in detail. Moreover, the feasibility of the proposed topology is verified by simulations and experiments on a laboratory prototype.

The application of FBD current examination method in the three-phase power system

In three-phase electrical power system, in order to compensate and control the harmonic current and the reactive power more effectively, this paper proposed an electric current testing method which is based on the method of FBD. This method can be used to detecting the fundamental wavepsilas negative sequence current, the fundamental wavepsilas zero-sequence current, the harmonic current and so on. The FBD method, compared with the other electric current testing method based on the instant reactive power theory, is more useful in the same situation. The result of PSCAD simulation has indicated the validity and the accuracy of this electric current testing method.

On-line fault diagnosis model for locomotive traction inverter based on wavelet transform and support vector machine

Abstract A traction inverter is the power source for rail transit vehicles. An insulated-gate bipolar transistor (IGBT) is the primary component of a traction inverter. IGBT faults can cause serious problems in locomotive power supply systems. The disadvantage of traditional fault detection methods for IGBT modules is a lack of real-time processing and high efficiency. An on-line fault diagnosis method based on a wavelet transform and multi-classification support vector machine (multi-SVM) is proposed for IGBT faults. Wavelet decomposition is used to process fault current signals, and energy vectors are constructed. Multi-SVM is used to establish a fault recognition model. The validity of this method is verified by simulations with MATLAB/Simulink.

Grid Connected Photovoltaic Power Generation Control Method Based on Swarm Intelligence Algorithm

Unipolar and bipolar modulations are widely used in the active power filter of photovoltaic grid-connected inverter. In this paper, the basic modulation strategy, on–off action, influence of operational mode, harmonic current and efficiency of unipolar modulation are compared with the same of bipolar modulation. On this basis, a hybrid modulation strategy integrating advantages of unipolar and bipolar modulations is obtained after analysis, of which effectiveness and feasibility is verified in experiment.

Design of high voltage vacuum circuit breaker's on-line monitoring and fault diagnosis system

A continuous real-time data acquisition and communication equipment based on Advanced RISC Machine and Field Programmable Gate Array is designed and developed, on the basis of which an on-line monitoring and fault diagnosis system for high voltage circuit breaker is realized. Mechanical, electrical and environmental parameters of the switching process can be gathered by this system. The function modules such as history data record and query, fault diagnosis, Ethernet communication and human-computer interface are contained as well. Ensemble Empirical Mode Decomposition based feature extraction method, Kernel Fuzzy C-means and Support Vector Machine combined fault diagnosis method are proposed and applied respectively. Performance of the system and precision of the algorithm have been proven in field tests.

Research on a Multilayer Distributed Online Monitoring System of 10kV High Voltage Switchgear

In order to meet the requirements of on-line monitoring for 10kV high voltage switchgear, a design of data acquisition, processing and communication based on a multilayer distributed structure is proposed. This system is composed of data acquisition and communication unit, distributed monitoring unit and remote monitoring terminal, with Ethernet communication scheme to enhance transmission rate and interoperability. Advantages of ARM and FPGA in the on-line monitoring field are explained, and on this basis a dual-core embedded main control unit is designed. The Timing control of FPGA to receive multi-channel data and the hardware and software settings in ARM to send data by Ethernet are detailedly introduced. The Ethernet packets sent by ARM are received by the industrial personal computer, which is responsible for the man-machine interface and data storage. Experiment shows that several electrical and mechanical variables can be real-time monitored by this system. The systems stability and accuracy in data processing are also verified in the experiment.

An error current tracking control method of three-level active power filter

In order to track the error current of three-level active filter more effectively, this paper presents a hysteresis current control method based on voltage space vector. Based on the conventional method, the selection of the resultant vector is no longer confined to a small sector the reference voltage belongs to. It finds out the optimal switching state through optimization in a large sector, which makes the track of error current by resultant vector more effective. From the perspective of control strategy, three-level active power filter based on LCL-type output filter using this control method has better tracking performance. Finally, the simulation and experiment validate the effectiveness of the proposed method.