© The Institution of Engineering and Technology
This study assesses four DC grid topologies where each of the terminals can exchange power with any other terminal and a DC fault on any DC cable can be isolated. The DC grids are built using the following components: hybrid DC circuit breakers (CB), mechanical DC CBs, DC/DC converters and DC hubs. The aim is to compare DC fault performance, technical feasibility/readiness, power transfer security, expansion and costs. The base case for comparison are three separate 300 km offshore HVDCs connecting 3 1 GW offshore wind farms with three onshore VSC terminals. The rating of DC CBs is limited by the state of technology and costs which introduces limitation on the length of DC cables (because of communication delays) and on the DC bus fault level (limiting the number of connecting DC lines). DC/DC converters inherently block propagation of DC faults and their rating is not sensitive to DC fault level. DC hubs have considerable cost advantages over multiple DC/DC converters in cases where multiple DC systems are connecting at the same DC station. The cost assumptions for all major components are analysed, including the offshore platform costs. The study concludes that overall DC grid costs are similar (within 8%) for all four topologies. Although power security is similar for all technologies, the expansion options are best with DC/DC converters or DC hubs. DC hubs nevertheless suffer from highest on-state losses.
References
-
-
1)
-
5. Descloux, J., Raison, B., Curis, J.-B.: ‘Protection strategy for undersea MTDC grids’ (Powertech 2013, Grenoble, June 2013).
-
2)
-
7. Bachmann, B.: ‘Development of a 500 kV airblast HVDC circuit breaker’, IEEE Trans. Power Appar. Syst., 1985, PAS-104, (9), pp. 2460–2466 (doi: 10.1109/TPAS.1985.318991).
-
3)
-
4. Whitehouse, R.S.: ‘Technical challenges of realising multi-terminal networking with VSC’. Proc. of the 14th European Conf. on Power Electronics and Applications (EPE 2011), Birmingham, September 2011.
-
4)
-
9. Jovcic, D., Lin, W.: ‘Multiport high power LCL DC hub for use in DC transmission grids’, IEEE Trans. Power Deliv., 2014, 29, (2), pp. 760–768 (doi: 10.1109/TPWRD.2013.2280759).
-
5)
-
6. Häfner, J., Jacobson, B.: ‘Proactive hybrid HVDC breakers – a key innovation for reliable HVDC grids’. CIGRE 2011 Bologna Symp., Bologna, Italy, , September 2011.
-
6)
-
3. Bell, K., Cirio, D., Denis, A.M., et al: ‘Economic and technical criteria for designing future off-shore HVDC grids’. Innovative Smart Grid Technologies Conf. Europe (ISGT Europe), .
-
7)
-
12. Kundur, P.: ‘Power system stability and control’ (McGraw Hill Inc, 1994).
-
8)
-
2. Taherbaneh, M., Jovcic, D., Taisne, J.P., Nguefeu, S.: ‘DC fault performance and cost analysis of DC grids for connecting multiple offshore wind farms’ (Powertech, Grenoble, June 2013).
-
9)
-
10)
-
1. Descloux, J., Rault, P., Nguefeu, S., et al: ‘HVDC meshed grid: Control and protection of a multi-terminal HVDC system’. CIGRE B4-308, France, 2012.
-
11)
-
13. Deng, F., Chen, Z.: ‘Design of protective inductors for HVDC transmission line within DC grid offshore wind farms’, IEEE Trans. Power Deliv., 2013, 28, (1), pp. 75–83 (doi: 10.1109/TPWRD.2012.2224384).
-
12)
-
8. Jovcic, D., Zhang, L., Hajian, M.: ‘LCL VSC converter for High power applications’, IEEE Trans. Power Deliv., 2013, 28, pp. 137–145 (doi: 10.1109/TPWRD.2012.2219560).
-
13)
-
14. Junyent-Ferre, A., Prieto-Araujo, E., Gomis-Bellmunt, O., Bianchi, F.: ‘Voltage sag ridethrough of PMSG wind turbines using droop control stabilization’. European Conf. on Power Electronics and Applications (EPE 2011), August 30 2011–September 1 2011, pp. 1, .
-
14)
-
10. ENTSOE: ‘Offshore transmission technology’. .
http://iet.metastore.ingenta.com/content/journals/10.1049/iet-gtd.2013.0838
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content/journals/10.1049/iet-gtd.2013.0838
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Topology assessment for 3 + 3 terminal offshore DC grid considering DC fault management