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Converter transformer bushing as a piece of important power equipment in HVDC transmission, need to withstand AC voltage, DC voltage, and polarity reversal voltage during operation, the complexity of the operating conditions leads to high requirements on the insulation performance of the converter transformer bushing. The dry-type SF 6 gas-insulated DC bushing meets the requirement of no oil in the valve hall, is the bushing of the current mainstream converter transformer, and it uses SF 6 gas as the upper additional insulation. Analyze the electric field distribution in SF 6 gas of converter transformer bushing under different voltages, Especially important for the design of SF 6 gas internal voltage equalization device. This paper selects ±400kV dry-type SF 6 gas insulated bushing as the research object, establishes a simulation analysis model, and uses the finite element analysis method to calculate the electric field intensity distribution of the converter transformer bushing under different voltages. Mainly analyze the distribution law of electric field intensity in SF 6 gas. The results show that under DC excitation, the distribution of equipotential lines in SF 6 gas is relatively concentrated, and the electric field intensity near the top of the capacitor core is the highest. Under the condition of polarity reversal, the electric field intensity in SF 6 gas showed a downward trend.

The insulation strength of high-voltage switchgear opening and closing break is the basis to ensure its safe operation, and it is also one of the important factors affecting its successful closing and breaking. In order to study the break insulation characteristics of the mixed gas of perfluoroisobutyronitrile (C 4 F 7 N) and carbon dioxide (CO 2 ), Build a test and research platform for dynamic insulation characteristics of C 4 F 7 N/CO 2 mixed gas break of the prototype circuit breaker closing-opening process under no-load high DC voltage, Measure the base pressure of 0.7MPa arc extinguishing chamber, the dynamic breakdown voltage of pure SF 6 , 5%C 4 F 7 N/95%CO 2 , 9%C 4 F 7 N/91%CO 2 and 13%C 4 F 7 N/ 87%CO 2 mixed gas, study mixed gas break insulation strength changes. The results show that, compared with pure SF 6 , C 4 F 7 N/CO 2 mixed gas break dynamic breakdown voltage dispersion is greater, the expected penetration time is longer than SF 6 ; increase the content of C 4 F 7 N in the mixed gas, The rate of change of the dielectric strength of the mixed gas break is improved.

During the breaking process of the self-blasting circuit breaker, the pressure characteristics greatly affect the action characteristics of the valve and the pressure in the expansion chamber, thus affecting the arc blowing effect. Therefore, a 550kV single-break selfblasting circuit breaker is taken as the research object. Based on the theory of magnetohydrodynamics (MHD), a two-dimensional transient model considering arc radiation is established, and the numerical calculation of the breaking process under two typical breaking conditions with short- circuit current of 63kA and 40kA and arcing time of 12ms is completed. The pressure and temperature distribution in the expansion chamber, and the action characteristics of the valve are obtained. Besides, combined with the test conditions, the 63kA short-circuit current, the pressure and temperature characteristics under short, medium and long arcing conditions are studied, and the valve action time under different conditions is obtained. The results show that the maximum temperature of the arc core region is 33219K at 63kA, which is about 3332K higher than the 40kA condition. The maximum pressure in the expansion chamber is 2.94MPa under the condition of 63kA and 2.36MPa at 40kA. The check valve is mainly affected by the temperature and pressure in expansion chamber side under the two breaking conditions, and the force received on the side of the cylinder is substantially same. The action time of the check valve under 63kA is 0.06ms earlier than the 40kA, and relief valve advance acts 0.05ms. Corresponding to different arcing time, the action time of check valve is 16.38ms, 16.28ms and 16.48ms and the time of relief valve is 17.52ms, 17.42ms and 17.67ms.

The phenomenon of DC magnetic bias in the ultra/UHV DC transmission has a very important influence on the stable operation of the transformer. The vibration method can be used to monitor the vibration characteristics of the transformer in real time. Therefore, The principle of transformer DC magnetic bias generation and its influence on transformer vibration is analyzed, and a transformer prototype vibration information acquisition and test platform is built. Under the simulated transformer DC bias state, air and load experiments are carried out respectively and vibration signals are collected. The vibration signal of different working conditions is extracted by Fourier algorithm. The vibration signal characteristic analysis method based on "frequency band-energy ratio-Euclidean distance " is proposed. The research results show that can effectively analyze the vibration signal of the transformer under DC bias state can be analyzed effectively by means of "frequency band-energy ratio-Euclidean distance" method, which can diagnose the vibration characteristics of the transformer.

Dividing wall column (DWC) was used to separate the system (1,2-propylene glycol + 1,3-butanediol + 1,4-butanediol). No research in a DWC has focused on such systems which were difficult to be separated for their great similarity in both molecular structures and properties. The rigorous steady-state and dynamic simulations, as well as the optimization of DWC alternative were performed with Aspen Plus and Aspen dynamics. Sequential quadratic programming (SQP) optimization method and the efficient sensitivity analysis tool were used to minimize the total reboiler and condenser duties. Moreover, a flow rate-composition cascade control structure was first developed to maintain targeted product purity under various external disturbances as feed flow rate and side product composition changed. DWC was compared with both a side rectifier configuration and conventional two-column distillation sequence in energy requirements and total annual costs (TACs) with the same number of stages. It showed that the energy requirements and TAC by DWC were reduced 47.60 % and 35.40 % respectively, compared with conventional distillation sequence, energy savings of 48.00 % and 34.11 % lower TAC compared with side rectifier configuration. This study provided a potential solution for the distillation of the systems with similar molecular structures and properties in a DWC.

Numerical calculation method on vibration of winding is researched in this paper. The 3D electromagnetic-structure model for a type S-11-M-500/35 transformer is established based on multiple physical fields coupling method. Firstly, the 3D- electromagnetic field of the transformer in the rated load current condition is established, the current, magnetic flux density and electromagnetic force of transformer are calculated. Calculated results of the electromagnetic force are coupled to the 3D structure filed model as force sources. Then, in order to analyze the transient vibration process of the transformer, the distribution of the vibration at different time and vibration curves in the 1/6, 1/2 and 5/6 positions of winding are calculated by considering the bolt preload and insulation block nonlinear characteristics. Finally, the vibration signal detection platform is built, load experiment test is made on the prototype, and the simulation results are verified by load tested data. The research method proposed in this paper can reflect dynamic characteristics of winding vibration accurately, which provides an effective method for further diagnosis on winding faults such as deformation and loosening caused by short circuit impact.

In the research of lightning protection in UHV substation, overvoltage will cause serious damage to the substation when the transmission line enters the lightning strikes. In this paper, combined with substation electrical main wiring, the UHV lightning transient characteristics of the module are considered. Then in the ATP-EMTP simulation environment, the GIS transient model of the key equipments such as pole tower, high voltage reactor and transformer are established under the lightning impulse. When the counterattack or the shielding failure strikes, the lightning intrusion wave overvoltage of a UHV substation GIS in different operating modes is calculated by comparing and analyzing the different types of arrester configuration. The results show that the outlet section and the high resistance share a set of arrester, and the main transformer installs a set of arrester to meet the equipment insulation margin requirement. The research results can provide reference for the arrester configuration of the station, and provide the theoretical basis for the lightning overvoltage protection of the UHV AC substation.

The existing blind source separation algorithm has two problems for the separation of the vibration signal of the transformer. One is the uncertain number of the transformer vibration source. The other is the vibration measuring point, which is not sure after the signal separation. Aiming at these problems, this paper apply the Wavelet-SVD-Clustering analysis method on determinating the number of sources by using one single sensor acquisition of transformer tank vibration signal. The effectiveness of the method is verified by simulation and experimental data analysis. The method of this paper provides guarantee for the correct analysis and separation of the transformer vibration signal.

Based on mechanical load characteristics of opening and closing operations of 40.5kV vacuum circuit breaker, a new type of permanent magnet brushless DC motor operating mechanism is designed. The main structural sizes of the drive motor are calculated by using the target value method. Through analyzing the performance of the same volume motor under different winding wire diameter and number of turns, the scheme of winding wire diameter and turns — more output torque, faster motor rotational speed, higher power density — is determined. The overall design of the drive motor is completed. The mathematical model of the motor is established with finite element theory. The dynamic rotational angular displacement and output torque of the motor are obtained. Compared with the pre-existing motor operating mechanism, the volume of new drive motor is reduced by 23%, and the average output torque and rotational speed can be increased by 53.4 N·m and 38 r/m respectively.

he temperature rise of GIS disconnector is a fatal factor that affects the power grid service performance. In this paper, a three-dimensional Finite Element Analysis model is established to analyze the magnetic-thermal field of disconnector cabinet. The distribution of magnetic field intensity and the values of eddy currents are calculated in the magnetic field first. Then the eddy current loss is coupled into the fluid-thermal field as a heat source to acquire the temperature rise value. Experimental values prove that this FEM model offers accurate results. So that the calculation method can be applied in the calculation of Magneto-Thermal Fields and the accurate parameters for product design and shorted the design cycle are provided.

A limited angle three-phase permanent magnet brushless DC (BLDC) motor operating mechanism for the 126kV high voltage vacuum circuit breaker is proposed and designed. The simulation model of motor operating mechanism is established by using the transient finite element method in according with the counter-force and the moment of inertia. The influence factors of the output mechanical characteristics is calculated and carried out, such as the rotor excitation structure, flux density, pole embrace, length-diameter ratio, turns-diameter ratio of the armature winding under the same poles etc. The simulation results indicated that the type of rotor excitation is employed the inset permanent magnet, which using the radial magnetization, the range of length-diameter ratio is 1.85 to 2.5, the pole embrace is bigger than 0.844, and the turns- diameter ratio of armature winding under the same slot is 14.28 to 23.7. So a larger air-gap flux density about 0.9T can be obtained, and the output mechanical properties parameters (such as output torque, speed and angle) meet with the requirement of circuit breaker.

In order to improve the performance of circuit-breakers, the influence of different magnetic materials on permanent magnetic actuators'(PMA) exciting current and operating characteristics are researched, and the finite element method(FEM) is used to establish the electromagnetic-mechanical coupled model. The electromagnetic equation, electrical equation and motion equation are solved to study dynamic characteristics of PMA. The yoke iron of PMA is made of cold-rolled silicon steel sheet and electrical pure iron respectively, the curves of the PMA parameters changing with time are obtained. The results show that the PMA with cold-rolled silicon steel sheet has better speed performance and less eddy current loss. A vacuum circuit-breaker with cold-rolled silicon steel sheet PMA is carried out, and in the corresponding experiments the operating characteristics are measured and the exciting current curves are also obtained. It is confirmed that the simulation results are accurate and have a certain actual significance.

The structure and parameters of the motor used in the operating mechanism is designed according to the characteristics requirement of disconnecting switch. The two kinds of stator winding structures, one of which is stator winding symmetric distribution and the other one of which is stator winding asymmetric distribution, are proposed in the motor design. The dynamic simulation is achieved by using the finite element method according to the two kinds of stator winding structures. The simulation results verify the reasonable of motor design and gain the characteristic curves (torque, current, revolution and angle, etc.). The analysis results indicate that both of the two stator winding structures motor have an excellent performance which can give a sufficient opening or closing speed to meet the requirements of disconnecting switch.

The morphology, composition and mechanism of the non-NBT phase in the Sr -doped NBT [SNBT, ( Na 0.5 Bi 0.5)1-x Sr x TiO 3] thin films by chemical method were investigated using XRD, SEM, crystallization analysis and thermodynamics analysis. The results showed that the non-NBT phase is the porphyroblastic grains in the matrix and looks like a plate-shaped polyhedron. The mechanism of the non-NBT phase formation is that the Sr 2+ and Na + combined with [Formula: see text] to form initial simple titanate, such as SrTiO 3, Na 2 TiO 3, or NBT phase decomposed because of the volatilization of Bi under a higher annealing temperature or longer annealing duration, and then transform into the secondary simple titanates ( Sr 2+,2 Na +) TiO 3 or ( Sr , Na )x Ti y O z. Moreover, the NBT phase disappeared for the SNBT films annealing at temperatures higher than 600°C and for 15 min.