Coupling Characteristics of Electromagnetic Disturbance of On-Site Electronic Device Power Port in Substations and Its Suppression
Abstract : The switching operations of circuit breakers and disconnectors in substations can generate very fast transients, including transient earth voltage rise and intense electromagnetic radiation, causing severe disturbance of on-site electronic devices in substations and seriously affecting the development of smart power equipment. The power supply of an on-site electronic device provides a path along which the disturbance couples with the device. In this article, we investigated the coupling mechanism and measures to suppress this disturbance.We found that, for most on-site electronic devices, their power supply includes a power line that connects the exterior and interior of the shielding box, greatly reducing the shielding effectiveness and inducing disturbance from the outside to the inside. This article proposes a shielding–crossing isolation transformer as the power supply of which the primary winding is outside and the secondary winding is inside of the shielding box, without a power line across the shielding box. This arrangement proved to deliver the high performance in terms of eliminating disturbance from the power supply. This article provides an understanding of the mechanism according to which the electromagnetic disturbance couples through the power supply. A method to determine the electromagnetic compatibility of on-site electronic devices in a substation is also proposed.
? Manufacturers of these devices are strongly urged to place warning labels on these doors and covers on all new devices.
? In addition, that they supply additional labels to existing users of in-service devices (for field installation) that have been certified by the manufacturer as meeting an IEC or IEEE RF immunity test.
? All existing power grid devices are immersed in an electromagnetic (EM) environment of natural and man-made EM sources that are either directly radiated into devices or are conducted via the power, signal and ground connections.
? The Smart Grid will introduce a great number of data flows in support of applications with widely divergent functions that can all be degraded by electromagnetic interference.
? 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.
• Test levels in this standard are proposed to be up to 30 V/m for radiated high frequency RF immunity.
• Also, “interoperability”, as defined with respect to the Smart Grid, is essentially the ability of two or more systems, networks, devices, applications, or components to communicate and operate reliably in real time. Hence, the reliable operation of the myriad communication systems proposed for Smart Grid applications is an essential prerequisite for interoperability no matter where the hardware is physically located.
• Another consideration is the increase in broadband PLC or broadband over power lines (BPL) technologies proposed for Smart Grid applications and home networking.
? An HF EMI coupling model based on the ADC after a performance test and finite element method (FEM) simulation was established.
? To study EM immunity with different grounding configurations and the coupling mechanism between the HF EMI, a series of the EM immunity performance of the ECT acquisition card was tested in a standardized laboratory.
? When exploring the EMC performance of the EUT, it is common to decompose the EUT into individual functional modules or ports, and then perform an EMC analysis from the system level, module level, and IC level according to actual needs.
? The enclosure of the ECT acquisition card, the GND of the PCB, and the power PE line were all equipotential in this work, and optical output ports have no effect on EMC performance.
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