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The impulse current is a transient current waveform, which has a short duration and cannot be repeated, so it is difficult to evaluate the influencing factors of measurement errors. This paper studies the traceability method and uncertainty evaluation model of impulse current measurement device, and the influencing factors of measurement error are analyzed. The impulse calibrator which can output standard double exponential impulse current waveform with specific time parameters (8/20) is developed. The peak value and time parameters can be traced back to the national standards of DC voltage and capacitance, inductance and resistance. The measuring system consists of standard impulse shunt and measuring instrument, whose peak current and time parameters can be traced respectively. The impulse scale factor of the impulse current measuring system is the product of the impulse scale factors of shunt and digital recorder. Finally, the performance of the measuring system is evaluated, and the expanded uncertainty of scale factor and time parameter is 0.4% (k=2) and 0.8% (k=2) respectively.

Transient voltage measurement is not only the design basis of insulation coordination of power equipment, but also related to the safe and stable operation of power grid. The transient voltage waveform in the actual power system is often the superposition of overvoltage and power frequency voltage. In order to measure this kind of superposition waveform, it is necessary to develop the high voltage test equipment which can produce the superposition waveform. Therefore, based on the circuit theory, this paper puts forward a parallel superposition circuit, respectively carries out mathematical analysis and simulation verification of the circuit principle, and determines the specific structure and key parameters of the circuit. On this basis, a set of high-voltage test equipment is set up by designing and purchasing high-voltage components and the overall control system of the equipment. The voltage waveform is observed by using voltage divider and oscilloscope. The test results show that the superposed voltage generator can superpose 500 kV positive or negative impulse voltage at any phase of 120 kV AC voltage.

Current is one of the most basic detection indexes in power system. In addition to the measurement of basic power frequency and DC current, the measurement of impulse current in power system is also very important. Its measurement accuracy is directly related to the measurement level of power system transient over-current and the safety of equipment and personnel. In order to measure the impulse current efficiently, conveniently and accurately, a broadband magnetic field sensor based on Archimedes spiral structure is developed. Firstly, the field circuit simulation of the magnetic field sensor with Archimedes spiral structure is carried out. The sensitivity of the magnetic field sensor is greatly improved, and the capacitance to ground is 1.0578pf. The rise time of step response is 20.4ns and the overshoot is 4.5%. The simulation results show that the magnetic field sensor has excellent high frequency characteristics and dynamic response characteristics. Compared with the standard shunt of State Grid measurement center, the amplitude error is better than 0.2%, the rise time error linearity is better than 0.2%, and the half peak time error linearity is better than 0.1%.

With the rapid development of the communications satellite, the problem of communication interference becomes more and more obvious. Once the interference appears, it needs to be solved quickly to ensure the smooth development of the communication service. According to the coverage characteristics of multi-track, multi-band, area beam and point beam of the communications satellite, the jamming positioning technology under different jamming scenarios is analyzed, and the optimal jamming positioning implementation method is studied, laying the Technical Foundation for the later period system construction application.

Lightning striking power system will produce a strong impulse current, and generate a very high ground potential rise on the equipment, which seriously endangers the safety of equipment and personnel. Therefore, the accuracy of impulse current measurement is related to the safe and stable operation of power system. In order to measure impulse current efficiently, conveniently and accurately, a wide frequency magnetic field sensor based on Archimedes spiral structure is developed. Firstly, the structure design and parameter calculation of the magnetic field sensor with Archimedes spiral structure are carried out. Compared with the traditional solenoid sensor, the single-layer sensitivity of the magnetic field sensor with Archimedes spiral structure is increased by 7.18 times. Through software simulation, the capacitance to ground of the magnetic field sensor is 1.0578pf; the rise time of the step response is 20.4ns, and the overshoot is 4.4%; the upper and lower cut-off frequencies of the magnetic field sensor are 3Hz and 21mhz respectively. The simulation results show that the magnetic field sensor has excellent high-frequency characteristics and dynamic response characteristics. Compared with the standard of national high voltage measurement station, the amplitude error is better than 0.2%, the linearity of rise time error is better than 0.2%, and the linearity of half peak time error is better than 0.1%. The non-contact accurate measurement of impulse current is realized.

A 500kV wide-band high-voltage divider for transient overvoltage measurement was developed. To improve the accuracy of the overvoltage measuement, the high-voltage arm of the developed voltage divider is based on a standard capacitor. By arranging equalizing electrodes reasonably inside the standard capacitor, the field strength distribution inside the voltage divider is optimized, and the overall size of the voltage divider is reduced. In order to optimize the dynamic performance of the voltage divider, it is equipped with excellent low-voltage arm components. The consistency of scale factor under AC voltage and impulse voltage for the divider is good. It can measure AC voltage with linearity of 0.2‰ under 500kV and measure lightning impulse voltage with linearity of 3‰ under 1200kV. The difference between AC voltage scale factor and impulse voltage scale factor is less than 0.01%. It can be used to measure transient overvoltage in substation and calibrate the noncontact transient voltage sensor and electric field sensor for field test.

For the traditional model based on the deep learning method most used CNN(convolutional neural networks) or RNN(Recurrent neural Network) model and is based on the dynamic character-level embedding or word-level embedding as input, so there is a problem that the text feature extraction is not comprehensive. In the development environment of the Internet of Things, A method of Automatic text classification based on BERT(Bidirectional Encoder Representations from Transformers) and Feature Fusion was proposed in this paper. Firstly, the text-to-dynamic character-level embedding is transformed by the BERT model, and the BiLSTM(Bi-directional Long-Short Term Memory) and CNN output features are combined and merged to make full use of CNN to extract the advantages of local features and to use BiLSTM to have the advantage of memory to link the extracted context features to better represent the text, so as to improve the accuracy of text classification task. A comparative study with state-of-the-art approaches manifests the proposed method outperforms the state-of-the-art methods in accuracy. It can effectively improve the accuracy of tag prediction for text data with sequence features and obvious local features.