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Gas-Insulated Transmission Line
Published in John D. McDonald, Electric Power Substations Engineering, 2017
The second principle solution is to control the power flow by use of electronic equipment in the transmission net using FACTS and HVDC equipment. FACTS stands for Flexible AC Transmission System, which is able to control the power flow on a transmission line via electronic valves (thyristors). HVDC stands for High Voltage DC and is using also electronic valves for power flow control with a DC transmission line between the two HVDC converter stations at its ends. This electronic control can prevent outages in cases when the power flow can be rerouted without creating new overload sections, bottlenecks, and other locations.
Applications III
Published in D.A. Bradley, Power Electronics, 2017
An HVDC converter will typically consist of a pair of six-pulse bridges connected in parallel on the AC side and in series on the DC side as in Fig. 6.2. Connection to the main AC supply will be by transformer, where by using a combination of a delta–delta transformer and a delta–star transformer to supply the bridges a 30° phase shift is introduced between the inputs to the two bridges to produce effective 12 pulse operation as seen from the AC system. In practice, each of the thyristor valves shown in figure 6.2 is made up of a large number of individual thyristors connected in series/parallel to provide the required current and voltage ratings for the converter.
The Backbone: Construction of a Regional Electricity Grid in the Arabian Peninsula
Published in Engineering Studies, 2018
Yet the GCC countries had to be inventive in connecting the seemingly incompatible Saudi grid to the rest of the region. Because American engineers built Saudi Arabia’s electricity infrastructures in the early 1930s, the country uses 60 Hz electric frequency, and is different from the rest of the Middle East and Europe, which rely on the 50 Hz standard.34 In ensuring Saudi Arabia’s connection to the region, GCCIA had to construct the world’s largest HVDC converter station, which permits sharing 1800 MW of electricity between networks that do not share a frequency. Located in Al Fadhili, an area known for its sand storms and high temperatures, approximately 100 km northwest of Dammam, the converter was built to remain in standby mode, awaiting a possible emergency, and only transmitting power between the two systems if one system suffers from a major loss. Despite problems with cooling the plant in a scorching environment, GCCIA believed that this location was efficient because of its proximity to Bahrain, minimizing the costs of laying submarine cables.35 The converter also had a secondary function: It would not only allow electricity flows between Saudi Arabia and the rest of the GCC, but would also act as a buffer. In explaining the converter’s significance, a Saudi electrical engineer told me how the famous New York blackout of 2003 could have been avoided if there had been such a converter in the grid – the converter would have confined the blackout to the zone where the infamous tree fell and caused an outage, precluding its expansion.
A High-Speed Protection Strategy for Bipolar CSC-Based HVDC Transmission System
Published in Electric Power Components and Systems, 2021
Som Jairaj Ankar, Anamika Yadav
Electrical failure is the divergence of the voltages and currents from the standard values or situations. Under usual operating conditions, power grids or lines bear natural currents and voltages which cause a more stable operation of the network. But as fault happens, it allows excess currents to surge, creating harm to machinery and appliances. Fault identification and inspection are important to choose or build suitable switchgear hardware, circuit breakers, electromechanical relays and other safety equipment. When faults occur on the AC system either rectifier or inverter side terminal. The proposed strategy needs the re-training of the BTEC-based fault detection model to detect the AC fault occurs on either side of the HVDC converter station.
Current-induced corrosion of aluminium heat sinks in water-cooling systems for high-voltage direct-current converters
Published in Corrosion Engineering, Science and Technology, 2019
Xuezhong Liu, Chenxing Wang, Ning Liu, Xiuying Jiao
In a high-voltage direct-current (HVDC) converter valve, an inner cooling system is installed to maintain the normal operating temperature of the thyristors via heat exchange between the cooling medium and the metal heat sinks [1,2]. Generally, deionised water is used as the cooling medium in HV converter valve cooling systems owing to its excellent performance in heat dissipation and electrical insulation [3–5]. Since the 1990s when water leakage caused by corroded couplings in HV valve cooling systems was observed for the first time, galvanic corrosion of metal components such as heat sinks and pipe couplings has been a worldwide concern [6]. Several measures, including device improvement of water treatment and installation of grading electrodes, have been proposed and applied to the engineering design, effectively reducing accidents caused by corrosion in the inner cooling systems. Consequently, the corrosion of heat sinks was considered to be no longer a threat over decades, until it was recently found to be associated with a new problem, i.e. the alumina deposition on platinum grading electrodes located in the water circuits. The depositing process has been proved to be electrically driven in the direct-current (DC) electric field around the polarised grading electrodes, while the aluminium contents in deposits turn out to be generated from the corrosion of aluminium heat sinks [7–10]. Currently, the deposition on grading electrodes, as a subsequent problem of corrosion in metal heat sinks, remains an unsolved problem in a number of HVDC converter stations, and operating accidents led by the fall-off deposits, including pipe blockage and water leakage, are frequently reported [7,11–13]. Therefore, although water leakage directly led by corrosion has been effectively prevented, the corrosion of heat sinks is still a threat to the long and safe operation of HVDC converters.