“Today, there is a need to have power conductors with improved current carrying capacity, reduced losses lesser sagging as well as lower aging effects,” urges Rajendra Mishra, Chief Operating Officer – Power Cables Business, Sterlite Technologies Ltd.
India, one of the most developed renewable energy markets in South Asia, is considered to be the third most attractive country to invest in renewable energy. It is also proposed to double the renewable energy capacity in India from 25,000 MW in 2012 to 55,000 MW by the year 2017. This would include further exploiting abundant non-conventional energy sources such as solar, wind power and energy from biomass.
Further, the country’s 12th Five-Year Plan recognised the importance of evolving a low carbon footprint strategy for environment friendly sustainable growth. Besides, setting a national target of increasing the efficiency of energy use, the Plan envisaged an expanded role for clean energy, including hydel, solar and wind power.
Global scenarioAcross the globe, the renewable energy sector continues to be more attractive as technology improves and costs decline. Also, transmission and distribution (T&D) of electric power is predominantly accomplished through bare overhead electric power conductors. For efficient use of energy and resources, reduction in T&D losses, high ampacity conductors to meet the ever increasing power requirement, lower sag property of the conductor to allow retrofitting on existing lines, robust and low maintenance conductors still remain a challenge to be met on priority.
ChallengesResistive losses incurred during T&D of electricity through electric power conductors is a major factor contributing to T&D losses. A popular solution to reduce resistive losses incurred in electric power conductors is the use of high conductivity material (or a material having low electrical resistance). While selecting an electrical conductor material, apart from its conductivity, there are several other factors too which need careful analysis. These include economic viability, physical and chemical properties of the material, safe operating temperature range for continuous power transmission at specific range of load, modulus of elasticity, strength, coefficient of linear expansion, ultimate tensile strength (UTS), resistance to corrosion, etc.
Apart from using high conductivity material, resistive losses of power conductors can also be reduced by improving their structure, components and design. Besides, the structure, components and design of overhead power conductor also play an important role in its overall performance such as ampacity, safe operating temperature for continuous power transmission at a specific range of load, robustness etc.
Special low loss conductor solution for T&D networksAs is known, the T&D network has technical losses as well as commercial losses. While commercial losses are a matter of law and order; technical losses can be reduced by the use of new generation conductors like ‘Sterlite Eco Conductor’. Family of these conductors has a low resistance and therefore results in low distribution network technical losses. Besides, these conductors have a property which offers high resistance to corrosion, which make these conducive for oceanic climate as well as polluted atmosphere.
In India, the distribution network is the largest segment of power network with distribution voltage ranging from 11 kV to 33 kV. Even 0.1 per cent saving in technical losses will mean saving in multi million units per day at national level. This would bring down the fossil fuel consumption. And, eco friendly conductors are a step towards this measure. Further, the cost of these conductors can be offset within a very short time by saving in losses offered by them. It may be important to note that these conductors may not need any special type of supports or line material.Technical dimensions and effectiveness The Eco Series conductors consist of trapezoidal shaped special aluminium alloy containing magnesium, silicon and copper stranded with round core. Further, the trapezoidal shape provides compactness to the extent of 96 per cent. When arranged and laid intelligently within an electrical power conductor, the non-circular cross-sectional shape of strands is useful in providing more conductor material per unit volume of the electrical power conductor. Hence, though the structural dimensions of electrical power conductor remain the same, due to better compaction and availability of more conductor material, current carrying capacity i.e. ampacity of the electrical power conductor is increased. In a particular embodiment of Eco Conductors, each of the non-circular cross-section strands are arranged within the conductor in a manner such that there is substantially little or no voids left in between said strand and strands which lie adjacent to it. Also, better compaction of strands helps in enhancing the robustness and reduction of sagging of the power conductor when hung between pylons.
Thus, these conductors are an innovative, efficient, low loss and most importantly an economical solution for re-conductoring power lines and constructing new lines. The higher efficiency of Eco Series Conductors also enables significant savings when substituted in grid systems for normal ACSR or AAAC conductors. Also for delivery of same power to the customers, Eco Series Conductors enables power generators to reduce the amount of power they must generate and hence lesser emissions. Hence with Sterlite Eco conductors I²R losses of distribution lines can be brought down by almost 30 per cent.
Some of the other benefits of Eco Conductors include:
For same output runs cooler by 5-10 C, hence lower carbon emissions
Contributing to reducing greenhouse gases
Can be deployed with existing structural designs.
ConclusionThe Indian industry offers numerous opportunities in the energy sector particularly in the case of clean energy technologies. However, the power sector, which is witnessing higher transmission infrastructure growth, needs greater power transfer capability per unit cost of ROW. In such a scenario conductors that deliver large quantity of current as compared to the conventional ACSR conductors offer best alternative. Further, any additional cost spent on new generation conductors and corresponding additional cost of supports, foundations or line material can be offset within a small gestation period due to increase in power transfer capability of the transmission line. This clearly indicates that the improvements have to be prioritised, and those giving very high returns with less investment, such as replacing conductors and releasing overload on the 11 kV -33kV line, should be identified and taken up first.
Sterlite Technologies has been developing and offering this technology to its customers, as a result of which they are able to increase the capacity of their transmission and distribution networks without the need to modify the structure and/or foundation of existing towers.