Cao Yundong

Dynamic arc modeling based on computation of couple electric field and flow field for high voltage SF/sub 6/ interrupter

In this paper, a dynamic arc model based on computation of coupled electric field and flow field for a high voltage (HV) SF/sub 6/ interrupter has been investigated and analyzed. Moreover, for simulating the insulating performance and interrupting characteristics of the SF/sub 6/ interrupter, dynamic variation of the arc in different interrupting cases, such as before current zero, approaching zero and after current zero have been established, and the compressibility and viscosity of SF/sub 6/ gas in the whole interrupting course has been taken into consideration. Interrupting performance and dielectric recovery characteristic of the HV SF/sub 6/ interrupter have been obtained and discussed. Fairly good representations of interrupting evolutionary processes within the arc-quenching chamber and arc dynamic characteristics have been achieved using the proposed model. And interrupting performance with higher precision has been obtained.

Hybrid finite element-charge simulation method for SF/sub 6/ tank type circuit breaker with double breaks analysis

The electric field simulation for the axisymmetric configuration of the SF/sub 6/ tank type circuit breaker is proposed based on the domain decomposition method in this paper. The mathematical model is based on coupling finite element method (FEM) and charge simulation method (CSM). It is shown that the hybrid FEM-CSM is capable in calculating the complex open boundary problem, demonstrating the great potential of the hybrid method in different fields.

Optimization design of the contact and shield in vacuum interrupter based on the genetic algorithm

In this paper, based on the electric field analysis, the optimizations for the end of floating shield and the back of contacts are realized using the combined method, charge simulation method (CSM) and genetic algorithm (GA). The floating shield potential has been successfully determined by the CSM. With the aid of solving the inverse problem and the computer simulation, the improved external dimensions of the floating shield and the contacts are presented. The theoretical basis for the insulation design is provided. Compared with the experiment on 35 kV vacuum interrupter, the computer results are reasonable.

Design on permanent magnet actuator and simulation of dynamic characteristic for vacuum circuit breaker

A novel Permanent Magnet Actuator (PMA) is put forward in this paper. The 3D magnetic distributions of PMA in different conditions have been computed, adopting ANSOFT9.0 software. In order to determine the size of each part of PMA, the variations of each parameter haw been simulated in dynamic course of breaking and closing. Based on the simulation results, the prototype is manufactured and assembled. The feasibility of the proposed PMA and the simulation veracity of the dynamic characteristic of breaking and closing hare been proved by the tested data of the prototype.

Survey on the external insulation of 10 kV outdoor vacuum circuit breaker

Taking the combined effects of porcelain insulation casing, the silicon rubber external insulation and floating shield on the electric field into account, the electric field has been calculated for three kinds of vacuum circuit breakers with different external insulation structures using the finite element method (FEM). The potential of floating shield has been well considered and calculated. Based on the computing results, the influences of floating shield and the silicon rubber insulation are analyzed. The theoretical basis for further optimization design of external silicon rubber and the development of outdoor vacuum circuit breaker is provided.

Electric field optimization design of the vacuum interrupter based on the Tabu search algorithm

During interrupting in the vacuum interrupter, the reignition between the contact and the shield are influenced by the shape of the contact and the size of the shield. The design for the contact and the shield is an intricate global optimization problem. In this paper, the Tabu search (TS) approach is used to optimize the contacts for the 35 kV vacuum interrupter. Optimization design is based on the electric field computation using the finite element method (FEM). By solving the inverse problem, the optimizations of the contacts are achieved, the reasonable distribution of the electric field is obtained. Based on the combinatorial optimization TS algorithm, an improved universal approach for the continuous variables global optimization is proposed. The feasibility and practicability are verified by the experimental results.

Research on a novel on-line monitoring system for Mechanical Characteristic of Circuit Breaker

Detection Device of Circuit Breaker (CB) Mechanical Characteristic is established in the paper, which takes TMS320F2812 as a core, and makes a logic extension. The necessary signal is collected, stored, and transmitted to position machine Upper memory block through CAN bus. The signal is analyzed and disposed, and the experimental data is transported to remote monitoring machine, thus the date is accumulated and information is shared. The paper improves maintenance level of CB, realizes the condition maintenance of CB, and enhances the efficiency of detection, so that this design has very important theoretical meaning and practical value.

Analysis on vibration and acoustic joint mechanical fault diagnosis of high voltage vacuum circuit based on wavelet packet energy relative entropy

In view of the requirement of high reliability and small disturbance in the condition of high-voltage (HV) vacuum circuit breaker (VCB), this paper puts forward a method of fault diagnosis based on online monitoring of vibration and acoustic signal. The research object is the 12kV indoor high-voltage vacuum circuit breakers and the system of fault diagnosis of the research object is built. This method uses fast kernel independent component analysis to make blind source separation processing for acoustic signals collected when HV VCB switch on. The wavelet packet energy should be calculated in each frequency of the vibration and acoustic signal. Support vector machine with the wavelet packet energy relative entropy as input vector to classify the common states, such as the normal condition, insufficient lubrication of the crank arm and mechanism fall off in moving. Experimental study has shown that, according to research on the characteristics of the vibration and acoustic signal generated by the circuit breaker, the proposed method can differentiate between normal working state and failure state and meet the high reliability of HV VCB status monitoring requirements.

Development of on-line monitoring system of switchgear

For improving reliable operation of switchgear in power system, an approach for on-line monitoring the insulation characteristic and bus-bar temperature rising of the switchgear is proposed in this paper. Through comparing several existing temperature measurement methods for monitoring temperature rising elevation at bus-bas, a new design of temperature monitoring method is proposed. It adopts quick-magnetic saturated current transformer, temperature sensor and infrared transmission to solve the problem of high voltage isolation. For switchgear insulation characteristic monitoring, using the micro-controller unit (MCU) and hardware design, an on-line dielectric loss angle and leakage current measuring method with low cost and high accuracy is implemented. Sensor and signal conditioning circuit design are adopted to ensure the accuracy of leakage current measurement. The frequency voltage signal is extracted by connecting voltage-dividing capacitor on capacitive device terminal and absolute method of measurement and zero-crossing comparison measurement is adapted to measure dielectric loss angle whose principle and calculation approach are presented in this paper. The leakage current and dielectric loss angle can be regarded as criterion to assess switchgear insulation characteristic. Because the monitoring system works in several electromagnetic interference environments, some hardware and software electromagnetic immunity measures are discussed. At last, the system runs in real system and the result shows the on-line monitoring system is stable and reliable which can be provide reference for on-line monitoring system design of switchgear.

Glow discharge simulation of argon gas based on PIC-MCC method

Gas discharge is an important phenomenon in high voltage gas insulation. A new method PIC-MCC is used here to study the glow discharge of argon gas in low pressure. A microscopic model is established in our work and numbers of charged particles were traced by particle in cell (PIC) method. Different from other PIC methods, the collisions between electron, ion and atom were also considered here and Monte Carlo method (MCC) was used to cope with the collisions. By the plane electrodes model, the formation of plasma sheath, the distribution function of electron, ionization rate, density of electron and the electric field were acquired at the pressure of 42mTorr and temperature of 293K. The effect of electrode voltage on the results was also discussed. The results acquired here can meet experiments well.