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The installation of surge protective devices (SPDs) is important for the protection of today's household appliances against in-rushing surge. The effective protection distance should be taken into account for the installation to avoid the influence of oscillation phenomenon. For household appliances, their port impedance characteristics are more complex and frequency dependent, and for some appliances, the impedance characteristics are different in operating state and nonoperating state. With the method proposed in this paper, operating state impedance characteristics of 16 different kinds of appliances are measured and the equivalent circuits are obtained by vector fitting and circuit synthesis. The protection effect of SPDs is simulated by electromagnetic transient analysis software using a practical distribution system model, and the effective protection distances of SPDs with different protection level for these appliances are obtained. Several analyses are made about relationships between the protection distance and factors such as the type of appliance, operating condition, and protection level. A case of protection for multiappliance is also analyzed.

Wideband frequency electromagnetic (EM) noise generated during the turn-on and turn-off processes of thyristor valves in converter stations is conducted along the primary circuitry, and may interfere with secondary systems. The EM interference (EMI) problem in a plusmn800 kV ultra-HVDC converter station is an important issue that should be studied carefully in the design stage. A method to analyze the conducted EM disturbance (EMD) based on time-domain wideband circuit simulation is proposed here, which is verified through the field test results of a plusmn500 kV converter station. Models of major equipment are described. The EMD levels of a plusmn800 kV converter station, which is currently being planned and built in China, are calculated, and compared with those of a plusmn500 kV converter station.

This paper describes the largest lightning location system in China-Guang Dong lightning location system (GDLLS), which only locates the electromagnetic fields radiated by individual return strokes in cloud-to-ground flashes. Using information gathered from 14 combined magnetic direction and time-of-arrival finder sensors, the GDLLS provides both real-time and historical lightning data to the electric utility industry. The real-time data include the time of lightning strokes, their location and polarity and an estimate of the peak current. In this paper, the performance of the GDLLS is addressed, including detection efficiency and location accuracy. The potential applications of lightning data collected by the GDLLS are discussed also for electric power utilities in the Guang Dong province.

The transient near-field of the electrostatic discharge (ESD) is strongly affected by the discharge current waveform. After analyzing several typical mathematical descriptions of the ESD current for the contact mode, two new mathematical descriptions of ESD current were constructed according to the polynomial of pulse function. These descriptions have the continuity of the first derivative at t=0 and are time-integrable. They proved to have little relative error compared to the IEC61000-4-2 standard