Hu Hongsheng

Transformer Power Fault Diagnosis System Design Based On The HMM Method

Once failures for large-scale transformer power occur, which will result in catastrophic economic losses and social impact. Therefore, it is necessary to design and apply a state monitoring and fault diagnosis system for large-scale transformer in order to improve the reliability and accuracy for power transformer during its running, which will benefit increasing the power enterprise economic performance, promoting economic and social development. This paper aims at large-scale power transformer, introduces Hidden Markov Models theory into power transformer fault diagnosis field, and a fault diagnosis method using the HMM is put forward. Some issues and their settling methods about the HMM applying into power transformer brings are further analysed. The fault diagnosis principle bases on the HMM is discussed in detail. The power transformer faults are classified and each of their characteristic variables is determined, accordingly, the fault diagnosis model library for power transformer is researched. Finally, the fault diagnosis system for large-scale power transformer is designed.

Wireless Monitoring and Assessment System of Water Quality Based on GPRS

Based on the knowledge about todays systems of water quality auto-monitoring and managing at home and abroad, a wireless monitoring system of water quality based on GPRS has been designed in this paper. And the model for water quality state recognition is established by BP neutral network based on water monitoring data. The software for wireless monitoring and assessment system of water quality is developed by using C++ Builder language and Matlab. The database is developed by using Microsoft SQL Server 2000.The experimental results show that the developed system which combines the wireless communication technology with the monitoring technology can greatly improve the real-time and continuity for the water quality state monitoring.

Application of Information Fusion Technology in the Remote State On-line Monitoring and Fault Diagnosing System for Power Transformer

This research focuses on the development of the on-line state monitoring and fault diagnosis system based on the information fusion technology for the power transformer during its running. In order to improve the fault diagnosis accuracy, a new fault diagnosis model combining the on-line monitoring of five characteristic gases dissolved in transformer oil with the feature extraction of three-dimensional temperature field of power transformer is put forward, which can realize fusion of the multivariate fault information of power transformer and improve greatly the fault diagnosis accuracy of the power transformer based on the information fusion technology. Besides, an embedded on-line state monitoring and fault diagnosis system composed of ARM and DSP is designed for the power transformer in this paper. In order to realize remote communication, a new method of data wireless transmitting based on General Packet Radio Service (GPRS) is designed. Finally, Simulation experimental results show that the developed embedded system can effectively monitor the state of the power transformer during its running and diagnose its fault. Therefore, the developed on-line state monitoring and fault diagnosis system will change the existing maintenance and repair pattern for power transformer and realizes accurate diagnosis or forecasts faults of transformer intelligently.

Design, control and test of a magnetorheological fluid fan clutch

The research is developed and aims at a new clutch using MRF as the transmission medium. Based on the theory of hydrodynamics and the rheology govern equations of magnetorheological fluids, torque transfer model of magnetorheological clutch is derived. The relationships between some designed parameters and outputted torque are analyzed. According to the magnetic circuit design theory, two designed methods of magnetic circuit for magnetorheological clutch are provided. Using Ansys software, its correctness of the theoretical calculation result is verified. Different spec magnetorheological clutches are designed and processed as test specimens. Besides, three control strategies, including double-control, PD control, fuzzy control, are respectively simulated in Matlab environment in order to analyze and evaluate their effect of temperature control. In order to improve the real-time, reliability and stability, an embedded system based on 89S51 microcontroller is designed and developed. A test and performance analysis platform for magnetorheological clutch is developed. And a series of experiments for magnetorheological clutch have been done, including its static characteristics, output characteristics and speed regulation characteristics. The experimental results proved its controllability of output speed for the designed magnetorheological clutch.

Performance simulation and experimental evaluation for a magnet-rheological damper under impact load

Many investigations have been done on low velocity and frequency applications of MR devices. The main purpose of this paper was to analyze the behaviour of the long-stroke MR damper under impact load and establish its dynamic model. Their relationships between some important designed parameters have been investigated in detail. According to the simulation result, a novel large-scale single-ended MR damper without the accumulator was designed and developed as the specimen. In order to simulate MR dampers performance under impact load, fuzzy controller and fuzzy PID controller were exploited to evaluate their controllability. Besides, a suit of intelligent monitoring and controlling system which used a closed bump to produce an impact load for MR damper was designed and exploited. Experiment results indicated that the designed MR damper could effectively reduce the shock vibration and achieve good control effect. Compared to other control methods, the fuzzy control strategy could reduce off 20% its displacement and pressure of MR damper under impact load.

Investigation on controllability of a Magnetorheological gun recoil damper

Its primary purpose of this study is to provide a comprehensive investigation on the controllability of a Magnetorheological (MR) gun recoil damper. Performances of MR damper under random load, mainly in the transportation applications, seismic protection in civil engineering and wind-rain-induced load in Cable Bridge, have been well investigated by many researchers. However, little research has been focused on the dynamic performance and its controllability of MR damper under impact load. At present, a systematic architecture has still not been formed, including its structure design, dynamicmodelling and controlling method of a MR damper subjected to impact load. In this paper, the research is developed and aims at the MR gun recoil damper. To evaluate its controllability of a MR gun recoil damper, a test rig which uses a closed bump to produce an impact load is developed. A novel large-scale single-ended MR damper without the accumulator is used as the specimen. First, impact tests were done to evaluate the response time of the special designed long-stroke MR gun recoil damper, corresponding to the step signal of the operating current. Then, three revised control strategies, including on-off control method, PID control method, adaptive fuzzy control method, were investigated to confirm its controllability of the MR damper under impact load. Compared with on-off control and PID control policy, it is indicated by test results that this developed MR gun recoil damper has a better controllability using the adaptive fuzzy control policy.

Research on the hardware-in-the-loop simulation of magnetorheological damper subjected to impact load

With the rapid development of structure design and the applications of high and new technology, more and more impact issues have occurred in engineering applications, especially in weapon system. This paper was explored and aimed at its dynamic character and vibration control of magnetorheological damper subjected to impact load. In order to evaluate its controllability of the designed long-stroke gun recoil MR damper in reducing the recoil displacement and damping force, a suit of hardware in the loop simulation platform based on dSPACE system and MR damper under impact load excitation is designed and developed. Based on the fluid mechanics theory, an amendment dynamic model of magnetorheological damper subjected to impact load is derived. Considering the impact load character and its strong nonlinear and uncertainty of a magnet-rheological damper, a fuzzy controller is designed and applied into the electromagnetic coil to achieve a control of active variable damping. The experimental results proved the derived dynamic modelpsilas correctness for magnet-rheological damper under impact load, and indicated that the designed large-scale single-ended MR damper and fuzzy controller could reduce off 40% its recoil displacement and pressure peak value of MR damper, which will further establish the basis of engineering application for a magnet-rheological damper under impact load.

Self-sensing Piezoelectric Actuator for Active Vibration Control Based on Adaptive Filter

The analytical model for the physical system composed of self-sensing piezoelectric actuators bonded on flexible cantilevered beam is established. Then, the error produced by the bridge circuit picking-up sensing signal is analysed in this paper. Alternatively, the theory of adaptive filter and adaptive noise cancelling system are introduced and the least means square adaptive algorithm is applied into the dynamic balance signal separation between piezoelectric self-sensing actuators and excitation signals, the ratiocinative process and convergence performance of the algorithms is further analysed, then the picking-up sensing signal for smart structure active vibration control by the LMS adaptive algorithm is simulated by the software. Finally, based on the digital signal processing chip and the adaptive filtering technology, the hardware and software of adaptive noise cancelling system is designed and realized to be applied into picking-up structure vibration signal. Experimental results show that the developed system can more effectively realize self-sensing signal separating and obtain the undistorted sensing signal, improve the controllers robustness for the smart structure active vibration control.

Research on Shape Control and Active Vibration Control of Piezoelectric Composite Laminated Shell

The shape control and active vibration control for the laminated shell bonded with piezoelectric sensors and actuators is researched in this paper. A set of vibration control equations, sensing equations and actuating equations are derived through using the finite element method and the modal theory for the piezoelectric laminated shell, then the model are converted into form of state space and transfer function. From the view of energy dissipation, the optimized placement of sensor and actuator units is analyzed with the genetic algorithm. From interdisciplinary view of structure dynamic and control, based on engineering background, considering defect and deficiency of conventional design method, structure and control integrated design is realized and the simulation platform is developed. Further, the active vibration control test for the advanced flexible composite barrel which is constituted with piezoelectric composite laminated shell is designed and developed. Experiment results demonstrate that the controller is able to suppress efficiently the flexible composite barrels vibration with piezoelectric laminated shell unit, which establishes further the basis of integrated design and engineering implementation for the weapon assemblage system active vibration control.

Test modeling and parameter identification of a gun magnetorheological recoil damper

Since its performance requirements of gun recoil mechanism have been continuously increased, this paper was explored and aimed at its dynamic model and parameter identification of a new type of gun magnetorheological recoil damper. Combining with its recoil resistance rule and stroke requirements of the 37mm caliber gun, a long-stroke magnetorheological recoil damper was developed. Using the developed hardware-in-the-loop simulation platform for weapon system under impact load excitation, impact tests for the special designed long-stroke magnetorheological recoil damper were done and its dynamic performances under different impact loads and input current were examined. Two nonlinear testing models based on Bingham model and Herschel-Bulkley model were respectively established, index parameters of the MR fluid and other structural parameters in these models were also identified using the least square algorithm. Finally, the validity of test models and identification parameters were verified. The experimental results indicated that the designed large-scale single-ended MR recoil damper under 16000N impact load could reduce off 40% its recoil displacement and pressure peak value, and its adjustability of the damping force of MR dampers could be well applied for gun recoil mechanism impact resistance design.