| Biography | |
|---|---|
 Dr. Sohrab Mirsaeidi Beijing Jiaotong University，Beijing, China |
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| Title: Commutation Failure and Its Consequences in Large-Scale Hybrid AC/DC Grids | |
| Abstract: Line-Commutated Converter based HVDC (LCC-HVDC) technology has been extensively utilized around the world for long-distance bulk-power transmission due to its merits such as the thyristor’s superior power handling capability and lower operating power losses. Nevertheless, the development of LCC-HVDC systems suffers from some well-known challenges such as poor voltage regulation ability and vulnerability to commutation failures during inverter ac fault incidents, which can lead to a temporary cessation of transmitted power, overheating of the valves, and misoperation of the protective relays. Commutation failures are frequent dynamic incidents which have been recorded in several existing LCC-HVDC projects around the world. They would become more problematic when several HVDC links terminate in one ac system such as concurrent commutation failures and forced blocking of five converter stations resulting from an inverter ac fault in South China Power Grid in 2010. Cascading fault can be a consequence of commutation failure in large-scale hybrid AC/DC grids which is defined as a sequence of events, initiating from a DC or a severe inverter AC fault and ultimately results in a blackout in the inverter AC side. In cascading faults resulting from an inverter AC fault, AC voltage across the inverter terminals dips which adversely affects the commutation process of the converter and leads to commutation failure. If commutation failure repeats for several times or lasts for a long time, it results in the forced blocking of the converter. The blocking of the converter shuts down the DC link and the power flow from the DC link is transferred to its parallel AC line. Since the capacity of the parallel AC line is much lower than the DC one, the overload protection of the AC line acts and a blackout happens in the inverter AC side. However, cascading faults caused by a DC fault occur because of the fault isolation by the HVDC line relays and are not accompanied by commutation failure. As a result, to study the mechanism of commutation failure and its consequences in large-scale hybrid AC/DC grids is of great importance. | |
| Biography: Sohrab Mirsaeidi received his Ph.D. degree in Electrical Engineering from Universiti Teknologi Malaysia (UTM), Malaysia in 2016. He furthered his postdoctoral research at the Department of Electrical Engineering, Tsinghua University, China from 2016 to 2019. Currently, he is an Associate Professor at the School of Electrical Engineering, Beijing Jiaotong University, China. Sohrab Mirsaeidi has published more than 50 papers and 2 books in the field of microgrids and large-scale power networks. Dr. Mirsaeidi is a member of the National Technical Committee of Measuring Relays and Protection Equipment Standardization of China, and has been involved in several national research projects in China. His main research interests include control and protection of large-scale hybrid AC/DC grids, distributed generation, and microgrids. He is a member of IEEE and IET, and a regular reviewer for IEEE. | |
