The setup for testing radiated disturbance induced by insulated gate bipolar transistor (IGBT) and auxiliary circuits was established. The radiated disturbance characteristics of auxiliary circuits and methods to suppress the radiated electromagnetic interference(EMI) were experimentally studied. The radiated EMI bandwidth of the auxiliary circuit was concentrated in 30-300 MHz. The mathematical model for an IGBT was proposed based on the setup, which includes all the structures of the IGBT in detail. The electric fields were calculated from the IGBT model using the method of moments (MOM). Moreover, the characteristics of the radiated disturbances due to the IGBT operation and the effects of metal on the radiated electric fields were experimentally and calculatingly studied in the frequency 1-30 MHz. The metal shielded box can increase the radiated electric fields by approximately 10-30 dB in 1-30 MHz. The electric fields for all frequencies decreased rapidly with the increase of distance. Additionally, methods to shield the IGBT in order to suppress the radiated EMI were proposed. The effective radiated EMI reduction from a shielded net was approximately 20 dB, and that of a shielded box was around 30 dB.

This paper is to study the effect of power line communication (PLC) system for power meter reading on electromagnetic environment. The experimental system of PLC for testing radiated disturbance is set up. The testing methods match the regulation of FCC Part 15. The simulation model of PLC is established using method of moment, and its effectiveness is verified by comparing the calculated results with the measured data. At application sites of power meter reading, the voltage at the beginning of the power lines and the radiated intensity at typical measurement points in the area are measured under three operating conditions of PLC system. Data reveal that the voltages are different under three operating conditions, which indicates that the impact brought by PLC operation is obvious. For the straight power lines, longitudinal distribution of radiation is fluctuant, and lateral attenuation of radiation is significant and rapid with a perceived range of 100-150 m. For crossed power lines, radiated distribution fluctuates remarkably. We can effectively predict the radiated distribution trend of PLC using simulation models. Moreover, multiple tests have shown that the radiated intensity in the application field is relatively high, because the environmental background noise plays a particularly large role. Comparing the operation and shutdown of the PLC system, the radiated contribution value can reach 15 dB at a lateral measuring distance of 10 m. Furthermore, we propose some recommendations for measurement methods.

Wireless sensor networks have been widely used in intelligent substations in power systems on the basis of the Internet of Things (IoT). The sink node equipment is the pivot of the wireless sensor network, and it is crucial for its reliable and normal operation for the communication of the wireless sensor network. However, transient radiated EMI generated by switching operations in substations affects the normal functioning of sink nodes. This paper proposed a transient radiated electromagnetic interference test method for sink node cables, and tested the interference characteristics of sink node cables in a substation. First, the transient electric field in the vicinity of the sink node of the intelligent substation is measured. Then, the test platform of transient electromagnetic field on the cable interference of sink node is established with standard waveform as the source of interference. Finally, the coupling characteristics for different frequencies and strengths of transient radiated electromagnetic interference to the device cables of sink nodes are obtained based on the experimental platform. The experimental data are compared with the measured data to verify the validity of the experimental results. The conclusions contributed to the EMC design of wireless network sink nodes in substations.

This paper focuses on the problem that the voltage recovery time of relay protection circuits in converter stations is too long under lightning surges. A surge protective device (SPD) in a relay protection circuit in an ultrahigh-voltage (UHV) converter station is investigated. Based on the action characteristics of a gas discharge tube (GDT) and metal oxide varistor (MOV) under a 1.2/50 μs lightning surge, the equivalent circuit model of a series-combined SPD is established. In the equivalent circuit model, this study considers the breakdown voltage, nonlinear impedance, parasitic capacitance, stray inductance and other parameters of GDTs and MOVs. Simulation analysis shows that a series-combined SPD can significantly increase the residual voltage and shorten the voltage recovery time of the protected system. To verify the simulation results, a test platform based on a low-voltage DC voltage divider was built for the lightning surge test. The test results are consistent with the simulation results, verifying that a series-combined SPD can meet the dual surge protection requirements of peak suppression and fast voltage recovery.

Switching operations in intelligent substations generate a wide range of extremely strong and asymmetric transient spatial electromagnetic fields, and this complex transient electromagnetic field can have a coupling effect with the wireless network sink node equipment cables. We conducted a study on the networking method of wireless network equipment in smart substations and analyzed the types of sink node cables used. In the GIS room of the 110 kV GIS smart substation, the transient spatial electromagnetic field generated by switching operation and the transient induced current of the sink node cable under different operating conditions were tested and obtained, and the time domain and frequency domain comparative analysis was performed. A near-field coupling model of the asymmetric and non-uniform cable transient spatial electric field at the sink node is established, and the validity of the model is verified by comparing and analyzing the measurement and simulation results. The results of the study can provide a reference for transient electromagnetic disturbances in 110 kV GIS intelligent substations and contribute to improving the reliability of wireless network equipment operation.

The optical fiber communication network is featured by strong anti-interference, good signal quality and other advantages. However, there are many equipment for the conversion of photoelectric signal is widely used in optical fiber communication network. When they are subjected to intentional electromagnetic interference radiation, it will affect their work, and even damage to the equipment, endangering the security of the entire communication network. In this paper, we selected fiber converter as the equipment under test, and selected high power microwave generation system as a source of interference to study the anti-interference of the converter under the high power microwave pulse interference. We find out the threshold interval when the converter's work affected under the L-band electromagnetic pulse interference by the experiment, and when the converter is installed inside the shielded cabinet can improve the anti-interference ability of the converter.