This chapter discusses man-made sources of electromagnetic interference (EMI) and mainly those present in the industrial environment. Electromagnetic interference includes frequencies in the radio spectrum (100 kHz to 100 MHz) that are known as radio frequency interference (RFI). Electromagnetic compatibility (EMC) refers to the ability of equipment to function satisfactorily without producing emissions that degrade the performance of other equipment, and are also not affected by emissions from other equipment. The international electrotechnical commission (IEC), through technical committee TC77 and its subcommittees, has established the new IEC 1000 series of standards to cover EMC requirements. The chapter reviews features that can be used to improve the harmonic and EMI performance of an AC variable speed-drive system. Harmonic distortion of the current waveform is also analyzed. Furthermore, the two main areas of EMI generation like supply side (mains) and motor side are also explored. Harmonic distortion of the current waveform is also studied. It is found that not all IGBT inverter drive applications will experience a problem.

Electromagnetic compatibility (EMC)

As the construction of smart grids is in full swing, the number of secondary equipment is also increasing, resulting in an explosive growth of power big data, which is related to the safe and stable operation of power systems. During the operation of the secondary equipment, a large amount of short text data of faults and defects are accumulated, and they are often manually recorded by transportation inspection personnel to complete the classification of defects. Therefore, an automatic text classification based on convolutional neural networks (CNN) is proposed in this paper. Firstly, the topic model is used to mine the global features. At the same time, the word2vec word vector model is used to mine the contextual semantic features of words. Then, the improved LDA topic word vector and word2vec word vector are combined to absorb their respective advantages and utilizations. Finally, the validity and accuracy of the model is verified using actual operational data from the northwest power grid as case study. 

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Short Text Classification for Faults Information of Secondary Equipment Based on Convolutional Neural Networks

The utilization of Fiber Optic (FO) in 5G communication systems has achieved several advantages such as increasing the capacity and the bit rate with a reduction in the total implementation cost. Radio over Fiber (RoF) systems could form the basis for 5G communication networks, due to several reasons related to its ability to provide the required bandwidth for the broadband data transmission to the end-users, other advantages are related with the lower loss in attenuation and higher immunity to RF (Radio Frequency) interference. Particularly, the utilization of Wavelength – Division - Multiplexing (WDM) and Dense - Wavelength - Division - Multiplexing (DWDM) techniques with the RoF system has gained all the attention of researchers in the last few years. As a result, this paper demonstrates a review of the proposed systems, schemes, and methods that contribute in enhancing the WDM and DWDM based RoF systems.

https://www.ijcnis.org/index.php/ijcnis/article/download/4887/434

WDM and DWDM based RoF system in Fiber Optic Communication Systems: A review.

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.

/pdf/electromagnetic-disturbed-mechanism-of-electronic-current-394nfiowsi.pdf

Electromagnetic Disturbed Mechanism of Electronic Current Transformer Acquisition Card under High Frequency Electromagnetic Interference

Air-core coil current transformer is a key piece of equipment in the digital substation development. However, it is more vulnerable to various faults when compared with the traditional electromagnetic current transformer. Aiming at understanding the effect of various parameters on the performance of the air-core coil current transformer, this paper investigates the influence of these factors using the maximum information coefficient. The interference mechanism of influencing factors on the transformer error is also analyzed. Finally, the Stacking model fusion algorithm is used to predict transformer errors. The developed base model consists of deep learning, integrated learning and traditional learning algorithms. Compared with gated recurrent units and extreme gradient boosting algorithms, the prediction model based on stacking model fusion algorithm proposed in this paper features higher accuracy and reliability which helps improve the performance and safety of future digital substations.

Error Analysis of Air-Core Coil Current Transformer Based on Stacking Model Fusion

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.

https://www.mdpi.com/1996-1073/13/5/1130/pdf

Electromagnetic Immunity Performance of Intelligent Electronic Equipment in Smart Substation’s Electromagnetic Environment

The invention provides a grounding device and grounding method for intelligent equipment electromagnetic compatibility detection. The grounding device includes a movable square timber and a wood table which are laid on ground in parallel; a grounding copper plate is laid on the wood table; a side portion of the movable square timber is provided with an interval-adjusting copper bar; and the interval-adjusting copper bar is connected with the grounding copper plate through a plurality of lined type connecting copper strips. The grounding device provided by the invention has the advantages of reliable grounding, low grounding resistance and convenience in movement detection.

Grounding device and grounding method for intelligent equipment electromagnetic compatibility detection

The invention relates to a balanced unbalanced transformer. The balanced unbalanced transformer comprises a coplanar waveguide power divider of a concentric structure; the power divider adopts a two-stage cascade form, and is formed by cascading two coplanar waveguides of concentric structures using Rogers 4350B as a base material; each concentric structure consists of an inner ring path line, a center path line and an outer ring path line from inside to outside in sequence; and each inner ring path line is electrically connected with the corresponding outer ring path line. According to the balanced unbalanced transformer disclosed by the invention, the available bandwidth is relatively wide, and all S parameters are easy to measure; and meanwhile, the balanced unbalanced transformer has better port isolation characteristic in a relatively wide frequency band range, and also has a relatively ideal phase characteristic.

Zhao Mingmin

Papers

Electromagnetic Immunity Performance of Intelligent Electronic Equipment in Smart Substation’s Electromagnetic Environment

Electromagnetic Disturbed Mechanism of Electronic Current Transformer Acquisition Card under High Frequency Electromagnetic Interference

Grounding device and grounding method for intelligent equipment electromagnetic compatibility detection

Balanced-unbalanced transformer and design method thereof