With the gradual increasing of the transmission voltage level, the situation of interference on secondary side equipment in smart substations is becoming more serious. The authors tested the interference waveforms caused by the circuit breaker’s operation at the smart substation, which showed the severity of the electromagnetic (EM) environment. This paper takes the electronic current transformer acquisition card as an example. The influence of EM interference sources on the reliability of the acquisition card is analyzed. Then, standardized electromagnetic compatibility (EMC) immunity tests of the international electrotechnical commission (IEC) for different interferences are implemented. Typical output characteristics of acquisition cards for different tests are analyzed. Innovatively, this paper proposes a quantitative evaluation method of output waveform disturbance to evaluate the acquisition card’s performance. This disturbance distortion is of great significance to the EM environment estimation of the acquisition card.

Wireless communication technologies play a key role to support the implementation of power grid Internet of Things (PIoT). An in-depth knowledge of the radio channel is vital to the application of wireless communication technologies in PIoT. This paper investigates the radio channel measurements and characterization for PIoT substation scenarios. A novel channel sounder is designed for achieving omnidirectional measurements and phased array antennas based directional measurements, and a directional multipath components extraction algorithm is proposed. The channel sounding system is verified and is used to perform a series of 3.35 GHz omnidirectional and directional channel measurements in four substation scenarios, involving a 10 kV switch room, a 110 kV GIS room, a semi-indoor 110 kV substation and an outdoor 220 kV substation. Based on the measured channel impulse responses data, both large-scale and small-scale fading characteristics of substation channels are extracted and analyzed. Empirical models of path loss, shadow fading, Ricean K-factor and root-mean-square (RMS) delay spread are proposed. In addition, results of RMS angle spread of departure and RMS angle spread of arrival are presented. These results will provide useful reference for the deployment and optimization of wireless communication networks in PIoT substation scenarios.

With the development of smart grids, the application of localized relay protection devices has greatly reduced the distance between the secondary equipment and the primary equipment. The secondary equipment will be in a more complex electromagnetic environment during the operation of the GIS disconnector. The present study takes the multi-path electromagnetic disturbance on the secondary cable caused by the disconnector switching operation of the domestic 1000 kV ultra-high voltage GIS test circuit as the research background, solves the field-line coupling problem based on the finite integral technique, and combines the multi-conductor transmission line theory to solve the radiation disturbance and obtains its influencing factors. The results demonstrate that the radiated disturbance accounted for 16% of the overall electromagnetic disturbance when both ends of the shielding layer are grounded. The use of grounding at both ends of the shielding layer, reducing the height of the secondary cable wiring, avoiding the parallel arrangement of the secondary cables and the GIS pipe mother, and installing a low-pass filter, have different levels of suppression effects on electromagnetic disturbances. The research results will guide the reasonable arrangement of secondary cables in GIS substations to some extent and have reference significance for the protection of secondary equipment.

The electronic current transformer (ECT) acquisition card is widely used in smart grids with many advantages. However, with the continuous improvement of the power grid and localized intelligent electronic devices, the electromagnetic environment under the operating conditions of gas insulated switchgear (GIS) substations is becoming more complicated. The reliability and safety of the ECT acquisition card will be endangered due to the complicated electromagnetic environment. In order to solve these problems, this paper investigates the electromagnetic disturbed mechanism of the ECT acquisition card. The effects of different grounding methods on the electromagnetic interference of the ECT acquisition card were studied. A platform based on IEC 61000-4-4 was built, and the electromagnetic interference (EMI) of the ECT acquisition card with different grounding methods was measured. The results show that the lower grounding impedance of the ECT acquisition system increased the internal EMI. Further, the high frequency electrical fast transient/burst coupling mechanism was analyzed. The parasitic parameters of the acquisition card were extracted based on the critical circuit by using the finite element method. Then, the high-frequency EMI coupling model of the ECT acquisition card was established.

This paper presents the analysis of electromagnetic radiation of mobile base stations co-located with high-voltage transmission towers. Although the layout of power poles and towers is uniform and symmetrical, the electromagnetic field radiated to the outside world is asymmetric. Field measurements were conducted in different co-located base station scenarios, and the field strength results in both the vertical and horizontal directions were analyzed in depth. Then, the ray tracing simulation method was used to obtain the electromagnetic field distribution characteristics for the 5G base station co-located high-voltage tower. Finally, the specific absorption rate (SAR) was adopted to evaluate human exposure in co-located base station scenarios, and a physical area-based human exposure assessment method proposed. The obtained results can be useful for inspectors of mobile base stations co-located with high-voltage transmission towers to avoid or reduce the impact of electromagnetic radiation.

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.