The country’s power system is witnessing disruptive changes. Alongside a phenomenal growth in installed generation capacity in recent years, the system is becoming increasingly complex, with the integration of a huge quantum of renewable sources and new demand loads like electric vehicles emerging. Further, with multiple generators, prosumers and decentralised generation sources, the grid needs to handle power flows in different directions, 24×7. Moreover, ageing infrastructure and a greater focus on performance and safety targets are also posing challenges.
Energy utilities are responding to these challenges by adopting digital technologies with the aim of helping users get actionable information and insights that enable better decision-making and asset management. Transformers are the immediate candidates for the integration of digital and smart grid technologies since they are the centrepiece of electricity networks today and are expected to play a much bigger role in the future power grid as it expands.
Digital transformers are becoming an integral part of the new electricity grid, which independently regulates voltage and maintains contact with the smart grid in order to allow remote administration and real-time feedback on power supply parameters. The use of these transformers is gaining ground at the distribution and transmission levels. These transformers are equipped with intelligent electronic devices, and smart monitoring and diagnostics features.
Need for digital
Over the years, a number of technological improvements have been made to transformers, which perform the important function of adapting voltage levels, stepping up for efficient long-distance high-voltage transmission and stepping down for distribution of electricity to consumers. These include ultra high-voltage AC & DC technologies, biodegradable oil-filled transformers, ultra-low sound transformers and high efficiency distribution transformers.
However, for many utilities, improving monitoring and optimising maintenance remain the top priorities. For instance, load peaks – predictable as well as unexpected – generate high temperatures that shorten the transformer life. In some cases, sudden failures may occur, causing havoc in the network and leading to financial and other penalties. Utilities are thus keen to control and monitor the status and condition of their transformer fleet so that they can intervene before a failure or malfunction occurs. Further, renewable power plants, operated by a large number of small, local energy producers, change the flow of power in the distribution network at the consumer end of the grid. The growing uptake of electric vehicles and the charging of these in residential areas introduce dramatic changes in consumption patterns. Heavy local charging activity can cause overloads on distribution transformers. There are many other indications that the number of critical nodes at the distribution transformer level will multiply, which will lead to a demand for the type of monitoring and control that has until now been limited to large power transformers.
To cater to the new and emerging grid challenges, digital transformers are increasingly gaining traction. Digital transformer solutions largely have three
blocks – hardware, software and services – that work seamlessly to deliver reliability, efficiency and future-readiness to utilities. Built-in components like digital sensors, dissolved gas analysers and digital safety devices collect data for monitoring, diagnostics and control at the local level. The same data can also be monitored and used for control, and preventive and predictive maintenance at the station control level via the cloud.
Transformers that come enabled with digital capabilities can enable remote monitoring and data analytics of its vital parameters in real time. This enhances reliability and enables higher utilisation of grid assets and power networks. Further, such transformers come equipped with a digital hub that can leverage a portfolio of smart devices on a modular platform with plug-and-play capabilities. In addition to enhancing efficiency and product life, digital capability can boost reliability and mitigate outages through preventive action.
A digital transformer provides the precise amount of power required and immediately responds to fluctuations in the power grid, acting as a voltage regulator. These features make digital transformers ideal for power systems that are designed for renewable energy integration. Meanwhile, at the distribution transformer level, digital distribution transformers provide intelligence to maximise reliability, optimise operations and maintenance costs, and manage the asset more efficiently. Technology providers are working towards integrating sensing technology directly into the transformer during the manufacturing process, thus resulting in higher accuracy.
Digital technologies are also being embedded by technology providers in dry-type transformers. Transformers typically use oil for cooling and insulation, but dry-type transformers are designed to work without oil, where the core and the coil are cooled by air and non-flammable solid insulation material. This makes them safer and more environmentally friendly. Such transformers are ideally suited for high-risk applications such as in offshore and densely populated areas, and in sensitive ecosystems. In digitally enabled dry-type transformers, smart sensors collect data and combine them to provide powerful analytics.
Digital technologies can also help improve safety. To this end, submersible transformer inspection robots are making inroads in the market. These wireless robots can be manoeuvred through a liquid-filled power transformer to perform fast, safe and cost-effective internal inspection, which can be shared remotely, in close to real time, with experts. This approach enhances safety by reducing personnel risk, reduces downtime with inspection performed in hours versus days, and brings inspection costs down by 50 per cent or more. Apart from the various aforementioned technical functionalities incorporated in the transformers, new digital transformers also address customers’ cybersecurity concerns. This is being done by adding additional layers of security such as RFID access card-enabled Wi-Fi. Moreover, the data stored is encrypted and the user needs a decryption key to be able to read the data. Also, the traditional cooling controls of power transformers are moving towards digitalisation. The traditional cooling control of power transformers has many limitations. One such limitation is that the cooling is grouped into banks, where the only possible operational states are no-cooling, half-cooling or full-cooling. For large power transformers, one such bank may consist of many pumps and fans. Using digital systems removes this limitation by allowing independent control of the cooler banks and thus providing a more fine-grained regulation of cooling capacity.
The way ahead
The massive growth in renewables-based power generation is resulting in greater voltage fluctuations in the distribution network and sometimes, even violations of the permitted voltage band. Inevitably, this will call for a healthy transmission and distribution system, which can act as a support for the smart grid. Grid communication will, therefore, become critical in the distribution network so that power generation and consumption can be balanced and voltage fluctuations eliminated. In this way, continuous, reliable and efficient supply of power will be maintained and voltage band constraints complied with. Obviously, transformers play a central role in power transmission and distribution networks and, going forward, as nodes of intelligence in the grid, will do a lot more than adapting voltages.