502 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 29, NO. 2, APRIL 2014 Power Transmission Over Long Distances: Economic Comparison Between HVDC and Half-Wavelength Line Milana Lima dos Santos, Member, IEEE, José Antonio Jardini, Fellow, IEEE, Ronaldo Pedro Casolari, Ricardo Leon Vasquez-Arnez, Gerson Yukio Saiki, Thales Sousa, Member, IEEE, and Geraldo Luiz Costa Nicola Abstract—In this paper, the economics of some alternative so- lutions for point-to-point transmission of bulk power over long distances, namely, HVDC and half-wavelength lines (HWLL), are evaluated. Also, the main technical aspects of the half-wave length transmission technology in order to define the line design and its re- quired equipment are discussed. A two-line, 2500 km transmission system (which is half the wavelength of a 60 Hz power frequency) carrying 6000 MW is used as the base case to perform the compar- ison. Finally, issues related to the sensitivity of such a cost compar- ison between the HVDC and HWLL alternative is presented. Index Terms—Half-wavelength lines (HWLL), HVDC, HVDC transmission, power transmission, ultra-high voltage (UHV) trans- mission, very-long-distance transmission systems. I. INTRODUCTION O NE particular feature of countries like Brazil is that its en- ergy grid embraces relatively clean electricity generation as more than 80% of its installed capacity (which is currently equal to 100 GW) is constituted by hydroelectric powerplants. The major load centers are located in the southeast region of the country, near the Atlantic coast. Building up new hydroelectric plants near these load centers is virtually impossible as the suit- able sites for such hydro schemes are all exploited. However, a big hydro-expansion potential exists in the tributaries of the Amazon River in the northern part of the country. These future powerplants are located more than 2000 km away from the load centers. Manuscript received March 26, 2012; revised October 11, 2012, February 26, 2013, April 11, 2013, and June 17, 2013; accepted July 06, 2013. Date of publication August 15, 2013; date of current version March 20, 2014. This work was supported in part by Electrobas Eletronorte, in part by Eletrobras Furnas, in part by CTEEP, in part by Cemig GT, and in part by EATE under the R&D program established by ANEEL (Brazilian Energy Regulatory Agency). Paper no. TPWRD-00318-2012. M. L. dos Santos and J. A. Jardini are with the Electric Power and Automation Engineering Department, University of São Paulo, São Paulo 05508-900, Brazil (e-mail: milanals@gmail.com; jardini@pea.usp.br). R. P. Casolari, R. L. Vasquez-Arnez, G. Y. Saiki, and T. Sousa are with the Foundation for the Technological Development of the Engineering Sci- ences (FDTE), São Paulo 05418-000, Brazil (e-mail: rcasolari@fdte.org.br; rarnez@fdte.org.br; gsaiki@fdte.org.br; thales.sousa@ufabc.edu.br). G. L. C. Nicola is with Eletrobras Eletronorte, Brasília 70716-901, Brazil (e-mail: geraldo.nicola@eletronorte.gov.br). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TPWRD.2013.2274333 The country has a vast transmission network connecting systems with 500 kV to most of the major centers; it also has systems operating at 345 kV, 440 kV, and 765 kV, as shown in Fig. 1. Particularly, the latter system carries 6300 MW (half of the power generated at the Itaipu powerplant) along three 800 km lines. The other half power of Itaipu is transmitted through an HVDC system (two bipolar lines) at 600 kV. Presently, two hydroelectric plants are being built along the Madeira River (a tributary of the Amazon River) each with 3150 MW which will use two HVDC lines at 600 kV over a distance of 2450 km to get to the load centers. Some other hydro powerplants are also being planned in the Amazon area and may also require long-distance transmission lines. One of them is the Belo Monte powerplant, located on the Xingu River, with nearly 12 000 MW. Currently, there is no half-wave transmission system (HWLL) commercially operating in the world. Also, the HWLL alternative still has some well-known unsolved prob- lems; this should be taken into consideration while choosing an adequate transmission system [1]–[4]. Nevertheless, the question as to whether this would be a desirable alternative for large systems like the Brazilian grid has always come up, and one of the reasons for keeping it quiescent has been the lack of a detailed economic comparison with other transmission alternatives. Therefore, it is deemed essential to develop a study on the technical and economical aspects of this alterna- tive to thereafter compare it with the HVDC alternative, which has several systems in operation throughout the world with reportedly good performance. Usually, the cost per kilometer of a properly designed line is less than that of an line. Conversely, the HVDC solution must include the cost of the converter stations. Hence, during the economic comparison, the cost of the lines and the HVDC converter stations has to be duly established. In order to per- form a stringent comparison between an HVDC and a HWLL system, it is necessary to get to some level of detail regarding also planning criteria [5], [6]. To do so (as a base case), a power equal to 6000 MW to be transmitted at a distance of 2500 km through two 765 kV lines was considered. It can also be through two 1000 kV circuits, thus, complying with the planning criterion. These two lines will be connected to the 500 kV sending and receiving-end grid through 6 1000 MW transformers (at each end) whose costs should be included in the total cost. 0885-8977 © 2013 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.