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The UHF method is one of the most important partial discharge (PD) detection means for GIS, while sensor technique is the key factor of the UHF method. In comparison with external sensors, inner sensors can achieve higher sensitivity. The paper firstly presents a key indicator of the sensor performance evaluation, and builds a simulation model of that. Secondly, the paper implements simulation research on the PD detection performance of the disc-type sensor, especially on the impacts caused by structural parameters based on the simulation model. The research achievements of the paper may provide reference of performance evaluation and design optimization for disc-type UHF sensors.

Defects inside the gas-insulated switchgear (GIS) will produce ultra-high frequency (UHF) electromagnetic waves. The waves will be affected by the shell of GIS when propagating inside the GIS cavity. In the 0-3GHz frequency range, propagation characteristic of electromagnetic which is excited by partial discharge in GIS is simulated based on the method of finite difference time domain (FDTD). This paper designs the GIS simulation models with and without insulator according to the size of a 220kV single phase GIS bus and sets a metal protrusion defect on the bus as the PD source. The transmission characteristics of model waves inside typical GIS structures, and the influence of the insulator to the propagation of electromagnetic wave was studied via setting the different directions of electromagnetic, comparing the time and frequency domain results of electromagnetic wave in different structures and measurement angles.

The UHF method is one of the most important partial discharge (PD) detection means for GIS, while sensor technique is the key factor of the UHF method. In comparison with external sensors, built-in sensors can achieve higher sensitivity. In this paper, two parameters were quoted to evaluate the performance of the sensor, which are He and S11. He refers to the PD detection sensitivity of sensor; S11 refers to the impedance matching property of the sensor. The paper firstly designed a simulation model of sensor performance evaluation, and then studied the performance differences of four typically used or researched built-in UHF sensors (i.e., disc-type, dipole-type, spiral-type and logarithmic-type) by simulation tools of CST. The conclusions of the paper can provide a reference for performance evaluation and type selection of UHF built-in sensor. Keywords: Gas Insulated Switchgear (GIS), Partial Discharge (PD), UHF, Sensor, Sensitivity

We report nanotesla resolution in a three-phase Metglas/FeNi/PZT-5A multiferroic composite with one end rigidly clamped operating in the first-order bending resonant mode for low-frequency magnetic field detection. Strong bending magnetoelectric (ME) couplings induced by the ununiform strain distribution in the free-clamped magnetostrictive beam are achieved without the benefit of nonmagnetic tip mass, and its natural resonant frequency is much lower than that in operating free-free mode. In addition, high-permeability materials Metgals are attached on the magnetostrictive beam for magnetic flux concentrating and resolution improvement. Experimental results reveal that the three-phase ferromagnetic/magnetostrictive/piezoelectric composite with a cantilever beam structure exhibits a high bending ME coefficient of ~32.17 V/cm·Oe at the resonant bending frequency of 819Hz under Hdc=175Oe. At the resonant excitation, the maximum resolution of 7nT is acquired under Hac=1Oe. The proposed ME cantilever structure with high resolution provideds a promising application in low-frequency magnetic transducer and sensors.

Partial discharge (PD) is the important detection parameter for power equipment, with the development of high voltage test technology, PD detection under impulse voltage is more attention. In order to detect the partial discharge signal under the impulse voltage, this paper designs a high-frequency current sensor and broadband measurement impedance. A set of partial discharge measurement system under impulse voltage is built up. The frequency characteristics of current sensor and measurement impedance are detected. In order to test the measurement system, the PD signals of a needle defect under impulse voltage is detected, the test results show that the PD measurement system can detect the PD signals effectively.

The impulse voltage test for power equipment such as GIS is not performed in the field for the impulse voltage generator huge and difficult to operate. The oscillating impulse voltage that proposed by IEC60060-3 is a higher generation efficiency impulse waveform and suitable used in field. The oscillating lightning impulse voltage generator for a 110kV GIS field test is studied in this paper. The generator structure is described and the waveform parameter computer formula is derivate. Simulation and test shown the generator can produce impulse voltage that meet IEC60060-3 requirement.

The paper designed a semicircle dipole inner sensor for UHF partial discharge detection in GIS. By comparing the symmetric semicircle dipole sensor and asymmetric semicircle dipole sensor characteristics, the symmetric semicircle dipole sensor’s coupling property is better than that of asymmetric semicircle dipole sensor. At the same time, by changing the symmetric semicircle dipole transducer radius, the position of the feeder pole , the height of the feeder pole, analyze its influence on sensor features.

For analyzing partial discharge ultrasonic wave characteristic on typical defects in SF6 gas insulation switchgear (GIS), a 110 kV GIS was taken as an object to design and simulate the typical partial discharge models in GIS� There are point electrode model on bus and cavity of GIS, floating electrode model, air interstice model in insulator, metal particle and iron core electromagnetic shock models. PD signals on different defects were thus detected with the ultrasonic method� The experimental results indicated that the ultrasonic signals of different defects showed different characteristics in waveform, amplitude and phase resolved partial discharge chart, which is helpful in PD pattern recognition for GIS�

To study the expressions of CD55 and CD59 in patients with hyperlipidemia and the effects of atorvastatin on it, and to identify the possible influential factors.We selected 67 patients with hyperlipidemia, and 24 healthy people matched in terms of age, sex and body weight as control. The expressions of CD55 and CD59 on white blood cells were detected by flow cytometry, and their relationships to blood lipids, complement activation indexes (C(5a), sC(5b-9)), inflammatory factors (high sensitivity C-reactive protein (hsCRP), TNF-alpha, IL-6 were analyzed. 24 patients with hyperlipidemia were treated with atorvastatin for 8-12 weeks and the expressions of CD55 and CD59 were measured before and after atorvastatin therapy.The mean fluorescence intensity (MFI) of CD55 lymphocytes and monocytes were decreased in patients with hyperlipidemia compared with control (2.07 +/- 0.28 vs 2.29 +/- 0.44 and 3.45 +/- 1.02 vs 4.33 +/- 2.32, P0.01 and P0.05, respectively). CD55 positive lymphocyte MFI was negatively correlated with waist circumference, waist-hip ratio, hsCRP and C(5a). C(5a) was negatively correlated with the MFIs of CD55 positive lymphocytes, monocytes, granulocytes, and positively with TG and diastolic blood pressure. After atorvastatin therapy, the MFIs of CD59 positive lymphocytes, monocytes and granulocytes increased (4.34 +/- 1.16 vs 3.69 +/- 0.76, 4.52 +/- 1.36 vs 3.91 +/- 0.89, 5.67 +/- 1.72 vs 4.56 +/- 1.03, P0.05,0.05 and0.01 respectively), which were not correlated with changes of blood lipids.The expression of CD55 is down-regulated in hyperlipidemia, which might be influenced by obesity, abdominal distribution of adipose tissue and inflammatory status of hyperlipidemia, but not by blood lipids. The expression of CD55 is related with complement activation; The expression of CD59 is up-regulated after atorvastatin treatment independently of blood lipids.