Jianyuan Xu

Surface vibration source number estimation of the 220kV running power transformer based on the Wavelet-SVD-Clustering

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.

Research on rural indoor cable leakage detection and localization

Through the analysis of the characteristics of most of rural indoor cable routing adopting wall concealed laying and there being more nodes in the lines, for the problems of leakage detection and location of rural indoor cables presenting small leakage current and different cable parameters in the same house, this paper designs a kind of handheld testing device with a certain precision and convenience. According to the magnetic field signal being generated by leakage current, inspection tour method is applied to leakage detection and location of rural indoor cable. The mathematical model of magnetic field generated by current carrying cable is established through Biot-Savarts Law. It is to calculate the size of a magnetic field generated by the leakage current. The leakage points are located by using the magnetic field signals differences before and after it. Applying MULTISM simulation verifies the feasibility of the signal processing circuit. Set up the testing platform, and measure the magnetic field generated by the current of less than 30mA, and further verified the feasibility of the analog circuit.

Research on joint coordination control of stand-alone wind-solar systems with battery storage

This paper presents a power coordinated control strategy based on the maximum power point tracking (hereafter for MPPT) control, load power point tracking(hereafter for LPPT) and battery charging and discharging according to the relationship between the system energy flow and the operation condition of Wind-solar Systems with Battery Storage (hereafter for WSSBS), and the realization method was presented referring to practical data. We comprehensively construct stand-alone WSSBS and take the actual light and wind speed as the input. Finally, the feasibility of the power coordinated control strategy is tested under the condition of the random wind, the light intensity and the load in the MATLAB environment.

Research the effect of UHV GIS disconnector contact shape on the multi-restrike

The multi-restrike during UHV GIS disconnector operation produces the very fast transient overvoltage (VFTO). In order to study the effect of contact shape on the multi-restrike process, this paper calculates the electric field of the disconnector gas cell based on the finite element method, and the contact gap breakdown voltage under different distance with different contact shape according to streamer breakdown criterion. Obtain the breakdown voltage characteristics between the contact gap using the least square method, building the multi-restrike simulation model of disconnector operation adopting ATP/EMTP software. Simulation results show that: under a certain operating speed, the breakdown voltage and the amplitude of high frequency transient oscillation pulse caused by breakdown are positively correlated; when operation phase angle in a power frequency cycle, the distribution of the maximum VFTO amplitude in the process of multi-restrike is approximately normal distribution. The value of contact fillet radius has certain influence on the VFTO amplitude.

Design of the new motor operating mechanism for 40.5kV vacuum circuit breaker

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.