Tennessee Valley Authority is installing ABB’s static var compensator (SVC) technology to help ensure system reliability as fossil fuel component of total energy mix declines. SVC’s enhance grid stabilization and at the same time enable a smarter grid.
The ongoing quest to deliver power with a lower environmental impact is a trend that is expected to continue given the carbon emission containment targets being adopted by major countries. In the European Union, for example, the ‘2020 package’ sets out a 20 percent cut in greenhouse gas emissions (from 1990 levels), 20 percent of EU energy from renewables, and a 20 percent improvement in energy efficiency.
Meanwhile, the US’s Clean Power Plan, unveiled in its final version by President Obama last year, aims to reduce carbon dioxide emissions from electrical power generation by 32 percent within 15 years relative to 2005 levels. The plan is focused on reducing emissions from coal-burning power plants, as well as increasing the use of renewable energy, and energy conservation.
Meeting future power demands and preserving the integrity of the electrical grid while concurrently curtailing and even shutting down fossil-fired generation, requires careful planning. Historically, coal power plants have provided base power supply as well as helped maintain grid reliability, by generating reactive power to regulate system voltage. As coal plants are taken out so is this essential part of reactive power and this can adversely impact the utility network by way of voltage drops, increased transmission and distribution losses, equipment failure and possibly even outages. This issue therefore needs to be addressed through the right technologies.
FACTS (Flexible Alternating Current Transmission Systems) technologies compensate for fluctuations in the voltage and current of an electric grid by instantly injecting and absorbing reactive power. Similar to a generator, FACTS devices can be used to control voltage levels, hereby allowing more power to flow through the network, improving system efficiency and preventing voltage collapse. . Such features allow the development of grids that are able to manage new complexities both on the supply and demand side e.g. intermittent renewables, more distributed power generation, demand management and new loads like electric vehicles and data centers.
Diversifying the generation mix
As sources of power generation in the US evolve to include more renewables and fewer conventional generating facilities, transmission planning activities are revealing potential reactive power related deficiencies. Tennessee Valley Authority (TVA), one of the largest public power producers in the US, is one utility that is diversifying its generating portfolio, recognizing the need to deliver clean, reliable and affordable energy to its nine million customers in Tennessee, Alabama, Georgia, Kentucky, Mississippi, North Carolina, and Virginia.
In seeking to provide reliable power, TVA evaluated possible solutions to ensure voltage levels are maintained throughout the network despite the closing of several coal plants. TVA contracted ABB to install a -100/+300 megavolt-ampere reactive (MVAR) static var compensator (SVC) connecting to a 161-kilovolt transmission network. SVCs are part of ABB’s family of FACTS and are a cost-effective solution to stabilize voltage levels, reduce transmission losses, increase capacity and defer the need for new power lines.
By the end of 2015, the utility had retired 19 coal-fired units with a summer net capability of 3,210 MW, contributing to the meeting of carbon dioxide reduction targets. And ABB’s technology continues to support TVA to reliably and efficiently deliver power to the people while minimizing environmental impact.