Renewable Energy Systems

A key factor in the feasibility and efficiency of modern grid-connected renewable energy systems is the increasingly sophisticated power electronics technology which controls and manages the generation, transfer, and distribution of electrical energy throughout the interconnected systems.  Inverters, coreless transformers, DC-DC converters and other power converters, are all examples of the power electronics devices which lie at the heart of all modern electrification technologies, whether they are grid-connected PV arrays, stand-alone wind turbine systems, or electric vehicles and charging stations. Their versatility and power-handling capabilities, along with their networking and reconfigurability features, have made it possible to plan and build the electrification infrastructures that are seen emerging today. 

While the outputs of power electronics circuits have become increasingly clean and efficient, there has also been a significant increase in the high frequency electromagnetic by-products of these systems, in the form of electromagnetic interference (EMI) which can leak out of the of a power electronics device through various mechanisms. Given the opportunity, these parasitic energies can propagate over nearby structures, cabling and other system components. The nature and extent of this propagation is often unpredictable. 

In other words, power electronic devices which may operate within acceptable EMI limits when tested in isolation (i.e. in product certification testing), can display different and unexpected behaviors and effects when placed within a system. The types, lengths and orientations of cable runs, the structural configurations and locations of metallic frameworks, and the grounding strategies being utilized are just some of the situational characteristics which may affect the propagation and intensity of interference signals on a system.

These unwanted and harmful effects can be mitigated or removed with appropriate shielding, filtering, grounding and other strategies. They can also be largely prevented at the design and installation stages by considering favorable options for system layouts and locations. In order to successfully implement those strategies, however, proper electromagnetic surveys and analyses first need to be undertaken, and should be followed up with adequate monitoring to validate their results.

These effects primarily occur due to the high switching frequencies, short pulse rise times, and high circuit densities which must be designed into the systems to produce the versatile and efficient outputs that are being demanded of them. Modern power electronics designs have been moving towards the use of Wide Band Gap (WBG) semiconductors such as GaN and SiC. These devices are capable of operating at higher frequencies and at higher power levels, potentially leading to energy systems with higher power capacity and higher efficiency.  However, due to their high frequency characteristics, they can also produce increased EMI. Many of the design challenges related to WBG converter development has to do with finding a balance between those effects. (Analysis and Suppression of Conducted Common-Mode EMI in WBG-based Current-Source Converter Systems | IEEE Journals & Magazine | IEEE Xplore)

These converter-based issues have become an area of research interest for organizations such as IEEE’s Electromagnetic Compatibility Society (EMCS) and Power Electronics Society (PELS). 

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