Zhi Zhang

Bio: Zhi Zhang is an academic researcher from North China Electric Power University. The author has contributed to research in topics: Signal processing & Coupling. The author has an hindex of 2, co-authored 4 publications receiving 8 citations.

A System of Calculation and Analysis of Torsional Vibration for Turbine-Generator Shafts

Abstract: Due to the disturbance of electric power system or other shock load, the torsional vibration of turbine-generator shafts occurs. Alternative shear stress due to torsional vibration decreases the shafts life, even results in shafts broken. It is significant to calculate and analyze natural properties and the responses of tosional vibration excited by the disturbance of electric power system in order to analyze and prevent catastrophic accident. The calculation and analysis system of torsional vibration of turbine-generator shafts is developed. With multi-mass lumped model, the model of torsional vibration of turbine-generator shafts is obtained. The system calculates the natural frequencies and the modal shapes of torsional vibration with the transfer matrix method, the response of torsional vibration of shafts with the increment transfer matrix method, such as torsional angle, angular velocity, angular acceleration, cross-section torque, and torsional stress. The response spectrum of torsional vibration can be obtained by fast Fourier transform algorithm Take an example of a 200MW turbine-generator, which is in the condition of non-all-phase operation. The responses of torsional vibration of shafts are calculated and analyzed. The bolt broken reasons of the coupling of inter-pressure rotor and low-pressure rotor and the coupling of generator and exciter are discussed. The results are identical with the data recorded in field. It is proved that the system is good precision, convenient using, friendly interfacing, and visual calculating.Copyright © 2007 by ASME

Research on High-Speed Multi-Channel Simultaneous Data Acquisition System

Abstract: In order to compare and analyze signals, it is usually necessary to acquire simultaneously and analyze multi-channel signals in practice and study, such as condition monitoring, fault diagnosis, automatic control, and so on. A high-speed four-channel simultaneous data acquisition system, based on DSP, USB 2.0 and CPLD, has been developed. This system takes full advantages of the ability of high-speed processing and analyzing of DSP, and of high-speed communication of USB 2.0. These make the system has an excellent integrative performance, meets the demands of the high-speed multi-channel simultaneous-acquisition. The system is smart, portable and flexible. A virtual dynamic signal analyzer based on this system has been developed

Portable high-precision event sequence recording tester

Abstract: The present utility model discloses a portable high-precision event sequence recording tester which belongs to the event sequence recording technology field The tester comprises a host computer and slave computers, wherein the host computer comprises a first power supply module, a liquid crystal touch screen, a man-machine interface module, a first control module, a first communication module, a first trigger signal output module and a first output channel, and each slave computer comprises a second power supply module, a second control module, a second trigger signal output module, a second output channel and a second communication module By adopting the tester, the absolute precision of event occurrence can be guaranteed, the clock synchronization performance of a detected system can be conveniently detected, the number of the slave computers can be reasonably chosen when a plurality of recording modules are testing objects, and the slave computers can be arranged on different positions and can be conveniently connected by cables

Portable high-precision event sequence recording test instrument and test method

Abstract: The invention discloses a portable high-precision event sequence recording test instrument and test method, and belongs to the technical field of event sequence recording. The test method comprises the following steps of: outputting a trigger signal to each channel of an event sequence recording module by the test instrument according to a selected test mode; and determining whether the channel trigger sequence for the test instrument and real-time record of the event sequence recording module are consistent so as to detect whether the function of the event sequence recording module is accurate. The test instrument has the advantages that absolute precision for event occurrence is ensured, the clock synchronization performance of a tested system can be conveniently detected, the number of slave computers can be reasonably selected when tested objects are a plurality of the recording modules, and the slave computers can be distributed in different positions so as to facilitate cable connection.

Tribological effect of piston ring pack on the crankshaft torsional vibration of diesel engine

Abstract: In this article, a mixed lubrication model considering the oil supply quantity and a friction model under dry running condition were developed, in which an elasto-plastic contact model was employed...

Design of Transient Recorder Based on USB 2.0

Abstract: The paper developed an transient recorder based on USB2.0 interface. It makes full use of the high-speed transfer capability of USB chips and FPGA technology to achieve high-speed acquisition for transient signal in the offline state, and uses FLASH memory to store the large-capacity data. At the same time, the instrument uses the power supply circuit of sensor to supply directly for the external sensor, and uses the lithium battery-powered unit to supply the entire system, so as to enhance its anti-jamming ability. The instrument which can be used for electrical equipment condition monitoring and fault recording features small size, low cost, convenient to use, and achieve a greater success in practical application.

Design of Circuit Board Schematic Validating System Based on Virtual Instrument

Abstract: When the circuit board schematic of spare parts are hardly obtained, it is of importance and significance that circuit board schematic validating system is designed, by which the circuit board schematic is calibrated and the spare parts can be designed and produced. On the basis of the combination of virtual instrument and developed in this paper, a circuit board schematic validating system is designed. Virtual instrument and its architecture are narrated in brief firstly. Then the system software design is developed. By applying the data acquisition cards, and Labview, the virtual instrument is built to schematic validating. The method used in this research can also be used another similar calibration systems.

Portable high-precision event sequence recording test instrument and test method

Abstract: The invention discloses a portable high-precision event sequence recording test instrument and test method, and belongs to the technical field of event sequence recording. The test method comprises the following steps of: outputting a trigger signal to each channel of an event sequence recording module by the test instrument according to a selected test mode; and determining whether the channel trigger sequence for the test instrument and real-time record of the event sequence recording module are consistent so as to detect whether the function of the event sequence recording module is accurate. The test instrument has the advantages that absolute precision for event occurrence is ensured, the clock synchronization performance of a tested system can be conveniently detected, the number of slave computers can be reasonably selected when tested objects are a plurality of the recording modules, and the slave computers can be distributed in different positions so as to facilitate cable connection.

Master-slave parallel collection device and method of artillery distributed data

Abstract: The invention discloses a master-slave parallel collection device and method of artillery distributed data for solving the technical problem of poor synchronism in the collection of artillery distributed data by the existing master-slave parallel collection device of the artillery distributed data. The technical scheme is as follows: a master-slave synchronous control manner between a collection host and a collection slave, and a double calibration mechanism of using a gigabit switch to perform delay calibration through parallel communication head information data are adopted to carry out delay deviation correction on collection devices through time compensation, so that the signal collection delays of collection systems are guaranteed to be smaller than 0.01 microsecond. The device disclosed by the invention is triggered by one host, and parallel trigger and parallel collection of at most 7 slaves can be driven at the same time, thereby solving the technical problem of large signal collection delays between the collection systems in the collection of the artillery distributed data, shortening the collection delay times of the systems and improving the synchronism of collecting the artillery distributed data.