The supply of reliable power is one of the key goals of power distribution utilities. This requires the efficient functioning of power distribution equipment such as cables, substations, switchgears and transformers. To this end, utilities are increasingly adopting digital solutions. In recent years, with digitalisation, the distribution equipment has undergone a design and technological upgradation. A look at the key technology trends in the distribution segment…
Switchgear and substations
Initially, the utilities installed air-insulated switchgear (AIS), which uses air as the primary dielectric for phase-to-phase and phase-to-ground installations. An AIS is a high-voltage substation commonly deployed in large areas. However, these substations are directly exposed to the effects of the climate and environment owing to their open design. In recent years, gas-insulated switchgear (GIS) has gained traction. It has a compact form and uses SF6 (sodium hexafluoride). Over time, GIS has gained popularity as it is suitable for deployment in urban and high density areas that have space constraints. Even though GIS entails higher capital and manpower training costs than AIS, it is relatively safer because of its closed design. Further, the failure rate of circuit breakers and disconnecting switches used in GIS is one-fourth of that in AIS and one-tenth in case of bus-bars. Moreover, GIS technology has less environmental impact than AIS as the SF6 leakage rate is less than 1 per cent. Utilities are also opting for hybrid switchgear-based substations, wherein the air-insulated bus-bars are integrated with gas-insulated equipment. Hybrid switchgear uses approximately 30 per cent less switchyard area, thereby facilitating quicker installation. The use of GIS technology in a hybrid solution allows rationalisation of switching elements and thus, offers more flexibility in bay addition. Utilities have also been deploying digital substations as these are equipped with advanced software that protect systems from potential cyberthreats, thus strengthening system security. Since all the components of the substation are automated, they enable faster implementation of new technological solutions. Further, utilities can track real-time data from these substations, thus ensuring enhanced asset management.
Cables and conductors
Distribution utilities are focusing on equipment that prevents power theft and ensures greater safety. Underground cables are being increasingly preferred to conventional overhead cables. In underground systems, cross-linked polyethylene (XLPE) cables are most commonly used. XLPE provides insulation to cables to make them withstand the electric field under transient operating conditions. However, these cables require a higher investment and longer restoration time (in case of any fault) as compared to overhead lines. In the cases of an overhead network, utilities rely on aerial bunched cables to prevent power theft, ensure reliability and increase ease of maintenance. Such a network is ideal for rural areas and congested urban areas. Further, technologies such as all aluminium conductor, all aluminium alloy conductor, aluminium conductor steel reinforced, and aluminium conductor alloy reinforced are being used in sub-transmission and distribution systems, depending on their power carrying capacity, cost, reliability, etc. To address the challenges pertaining to the increasing load, utilities can deploy high temperature superconductors. These conductors have the capability of carrying five to ten times the current carried by conventional conductors. Moreover, these are compact in size and have a lower right-of-way requirement.
The conventional oil-filled transformers are being replaced with dry-type and K-class fluid-filled transformers, which offer lower failure rates. The use of dry-type transformers and ester fluid-filled transformers is on the rise as they offer better protection against fire hazards, have reduced/no risk of leakage of insulation fluids, and entail minimal maintenance. These are key factors in the installation of these transformers in densely populated areas. Further, such transformers offer additional features including hermetically sealed tanks, lower noise levels and reduced losses. Original equipment manufacturers are also offering smart transformers, which allow remote monitoring and provide real-time updates on power supply parameters, while reducing the overall carbon footprint.
Overall, the technology trends in the distribution segment have been largely driven by the need to reduce space requirements, enhance safety and efficiency, and integrate smart technologies. While the high upfront costs of new technologies may hinder the roll-out, the long-term efficiency gains are expected to justify the costs. Going ahead, utilities need to continue adopting newer technologies and smarter solutions to ensure reliable power supply to consumers.