India is significantly expanding its installed renewable energy capacity to meet its net-zero goals. However, this rapid growth in capacity requires the development of transformers, reactors, substations and other transmission and distribution infrastructure. Transformers are pivotal in managing power system resources, traditionally being used for stepping up and stepping down electrical energy at different points of the power system. As renewables gain prominence, integrating this intermittent energy source into conventional power grids presents challenges. Consequently, transformers need to be adapted to continue fulfilling their critical role in power system management by integrating renewable energy power transmission and distribution.
Transformer technology
Solar energy is converted into electrical power through photovoltaic (PV) cells, producing direct current (DC). Inverters then convert this DC power into alternating current (AC) before it is connected to the grid through a step-up transformer. These transformers synchronise the AC output with the grid’s phase frequency and voltage, ensuring smooth integration. However, design challenges arise with solar power systems, requiring separate windings in transformers to accommodate diverse inputs and long cable runs for DC to AC conversion. Inverter size restrictions also pose limitations, complicating efforts to scale up PV systems by adding more inverters. Despite advancements, inverter technology has progressed slower than wind turbine technology. Further, isolation transformers are often employed to shield inverters from grid surges and prevent DC injection, although they increase costs and decrease efficiency.
Another transformer technology suitable for renewable energy sources is solid-state transformers (SSTs), which consist of control circuits, high-power semiconductors, and high-frequency transformers, enabling smooth conversions between AC and DC. They provide enhanced control over power distribution networks and autonomously regulate voltage fluctuations when integrated into the grid. Compared to traditional transformers, SSTs offer increased robustness, reliability, efficiency and cost-effectiveness.
Apart from this, both dry-type transformers and liquid-filled transformers are increasingly utilised for handling and transmitting large amounts of electricity from variable renewable energy installations. Dry-type transformers enclose windings and cores in a sealed tank filled with air or pressurised gas, commonly connecting renewable energy technologies such as wind turbines, solar panels and hydroelectric plants to the grid or loads. Meanwhile, liquid-filled transformers utilise fluids such as mineral oil, synthetic ester and natural ester, making them suitable for applications ranging from residential to commercial and industrial rooftop solar installations, as well as onshore and offshore wind projects.
There is growing traction in the implementation of internet of things (IoT) technology in transformers as it enables real-time data collection on power system performance, empowering power companies to proactively address potential issues and prevent system outages. By integrating artificial intelligence and machine learning into IoT systems, grid vulnerabilities can be predicted more accurately through advanced modelling and warning systems. This enhanced diagnostic capability facilitates improved maintenance scheduling, leading to reduced operations and maintenance (O&M) costs.
Smart transformers represent an upgrade from conventional counterparts, adept at managing bidirectional energy flow and enabling electricity exchange between prosumers and consumers. These intelligent devices continuously monitor energy output and grid demands, automatically adjusting performance for optimised transmission. By enhancing grid flexibility through real-time monitoring and control, smart transformers improve stability and maximise energy flow for a more responsive and resilient energy infrastructure.
Some of the other emerging technologies in the transformer industry are high voltage direct current (HVDC) converter transformers, phase shifting transformers (PSTs) and coupling transformers. HVDC converters offer efficient transmission of electricity over long distances with reduced losses compared to high voltage alternating current systems. PSTs regulate line and phase voltage independently of energy generation, which is particularly beneficial in networks with significant power wheeling. Coupling transformers enhance control and stability in flexible AC transmission systems.
Conclusion
The evolution of transformer technology, driven by renewable energy integration and advancements in IoT and smart systems, has significantly enhanced the efficiency, reliability and resilience of power grids. In the forthcoming years, the increasing capacity of renewable energy sources will require concurrent investments in the transmission and distribution sector. This will involve upgrading infrastructure and integrating smart technologies to effectively manage the volatile, intermittent and bidirectional flow of electricity.