Mike Dickinson, Pacific Crest Transformers
For years technologists have been toying with the idea of a smart grid, and adoption of the smart grid is expected to enhance every facet of the electric delivery system. Transformers are a key component of a successful smart energy transition, making them immediate candidates for integration into the technology. Most of today’s transformers, however, are by no means ready for the smart grid because they were placed into service years before the age of interactive information transfer. Building next generation transformers will require incorporating remote monitoring of a wide range of transformer and system parameters.
What is a Smart Grid?
The definition of smart grid is fluid. The U.S. Department of Energy (DOE) notes that the smart grid will be an automated, widely distributed energy delivery network, characterized by a two-way flow of electricity and information and able to monitor everything from power plants to customer preferences to individual appliances.
Distributed computing and communications technology will be incorporated to deliver real-time information and enable the near-instantaneous balance of supply and demand down to the device level. In short, the smart grid will deliver electricity from suppliers to consumers using digital technology to save energy, reduce cost and increase reliability and transparency.
Table 1 compares key features of today power distribution grid with that of a smart grid. Adoption of the smart grid is expected to enhance every facet of the electric delivery system, including generation, transmission, distribution and consumption.
To say a lot is riding on a successful transition to a smart grid is a colossal understatement. The smart grid is expected to ensure the reliability of the power system, maintain its affordability, reinforce the United States’ global competitiveness, fully accommodate both renewable and traditional energy sources, potentially reduce our carbon footprint and be structured to facilitate the introduction of new advancements and efficiencies that have not yet even been dreamed.
Table 2 lists the key component technologies that are expected to be available to facilitate transition to the smart grid.
Today’s Transformers are not Ready for Tomorrow’s Smart Grid
Although just one piece of the smart grid puzzle, transformers serve a key role as the hub for collection and distribution of energy. Smart transformers will be needed for the smart grid to work efficiently. As part of the distribution network, millions of transformers are installed in the country; unfortunately, few of them have any intelligence or communication capabilities that meet advanced metering infrastructure (AMI) standards or are parts of an advanced sensor infrastructure (ASI) network.
Transformer manufacturers see an increased emphasis on online transformer monitoring, but today’s transformers are, for the most part, not ready for tomorrow’s smart grid.
The first reason for this is because transformers have a long useful life expectancy, generally 20 to 30 years of service. Most were installed before the age of interactive information transfer, which is the foundation of a smart grid.
As they are replaced with contemporary technology, communication capability can be included as an upgrade. A product with such a long projected useful life span, however, changes only gradually over time. A transformer’s life span is about 25 years, therefore, each year only 1/25th of those installed would likely need to be replaced. Optimistically that’s only 4 percent per year for the next 25 years. That is a long time to wait for a smart grid, if typical replacement patterns apply.
A second reason is that the wide range of transformer applications means some transformers are in a position/location/application where grid communication is mature enough to allow/require interaction, while others are not. Transformers used in power transmission are immediate candidates for integration into smart grid technology, while transformers used mainly for distribution circuits will be affected by a smart grid only after it matures to a greater degree.
Another key factor is the need for a sea change in how the industrial sector sees transformers. Its concern has traditionally focused on power continuity; heavy industrial users have typically not paid a great deal of attention to how their transformer can be used to affect power flow or load switching on a regional or national scale. The danger with this mindset is that industrial transformers being purchased today, which will be in service for the next 20 to 30 years, may not contain the systems necessary for monitoring communication likely to be required within the next five years. Clearly, transition to the smart grid will require a degree of re-education in the industrial sector.
Legislation also may play a part in accelerating the change and transition to transformers that are compatible with smart grid concepts. Recently, DOE mandated higher efficiency ratings for all distribution transformers in 2010, and in the late 1980s legislation mandated that PCB-contaminated transformers be replaced.
Monitoring is Key
Digital monitoring is already used in many transformers. Vital statistics like temperature, pressure and vacuum levels are collected and transmitted in real time to a central clearinghouse. Many transformer manufacturers recognize this growing demand for online transformer monitoring products and diagnostic services and they’re investing in building them, especially for step up transmission high voltage transformers.
These technologies will be critical for improved grid reliability and helping utilities avoid transformer failures and resultant blackouts. They will also reduce maintenance costs and defer capital expenditures by extending a transformer’s useful life.
For example, in the past few years, a burgeoning interest has existed in conducting dissolved gas analysis (DGA) of transformer oil. With DGA, samples are taken of the oil’s exhaust gases to determine if any events have occurred that might be detrimental to the transformer and reduce its life. Both industrial transformer users and utilities are setting up these planned sampling programs, using online devices that can monitor the oil for quality. This can greatly improve reliability, because users will know in advance when something has to be replaced, rather than risk enduring an unscheduled outage. For food processing plants and mills, which can lose millions of dollars if their power is interrupted, this type of sampling program is being used to ensure reliable power.
Transformers in place now already use various smart devices for load switching. In the 21st century, the move will be toward monitoring systems that promote transformer reliability. Transformer manufacturers will focus on ensuring reliability on the grid by replacing equipment before it fails and anticipating upcoming problems. Table 3 shows typical monitoring parameters necessary for smart grid integration.
The use if these smart grid concepts to ensure system reliability is still in its infancy. All system parts must work together to develop a system that monitors the transformer and other parts of the grid at all times. A bit of an island mentality still exists among those building system components, including switches, cabling and capacitors. Symbiosis among the components could happen, but it has not done so yet.
The answer to the question “Is your transformer ready for the smart grid?” is complicated. Depending upon where the particular transformer is used in the power generation and distribution system, the answer is yes, no or maybe.
Mike Dickinson is the director of new business development for Pacific Crest Transformers. He has 37 years experience in transformers, including design, manufacturing, training, testing, marketing and sales of distribution, small power and high voltage CTs, PTs and CVTs up to 230 kV.
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