BACKGROUND:
The sub-transmission grid in the Asia Pacific region faces various challenges and opportunities for development aimed at improving energy distribution and reliability. The region includes countries ranging from the world’s largest energy consumers to small island economies highly vulnerable to climate change. Asia Pacific accounts for nearly half of global energy consumption, with fossil fuels
comprising 85%. As urbanization and industrialization advance, energy demand rises accordingly.
Increasing energy generation through clean energy sources such as solar, wind, and hydro is crucial for transportation, heating and cooling, and manufacturing and industrial processes. The rise in generation necessitates investment into the region’s grid to extend medium-voltage lines to rural areas, improve access to reliable electricity, and support economic development and growth.
The Asia-Pacific region is expected to remain a leading market for renewable energy development and investment over the next decade. A decarbonized future largely powered by renewable electricity generation hinges on a reliable grid, particularly the transmission grid. Hydroelectric power is the largest source of renewable energy in Asia Pacific. As the costs of solar panels and wind turbines decrease, the energy generated by these sources has increased.
The ability to sectionalize and reroute power during sub-transmission system outages greatly enhances reliability, as highvoltage grids serve numerous homes and businesses. According to the PwC Net Zero Economy Index 2023, Asia Pacific economies need to reduce their emissions by 17.2% annually to reach net zero by 2050 and limit global warming to 1.5°C.
The high costs and environmental impacts of status quo solutions
G&W Electric’s Viper®-HV recloser is an important innovation in efforts to simultaneously reduce utility operating expenses (OPEX), improve sub-transmission grid reliability, and integrate more renewables. The genesis of the Viper-HV recloser was when two utilities approached G&W Electric, one of the U.S.’s largest recloser and switchgear manufacturers, with the request that the company develop a 72.5 kV recloser able to switch and sectionalize sub-transmission power lines to maintain reliability.
The reason the utilities and the wider industry were so keen on an overhead solid dielectric solution able to enhance sub-transmission grid reliability was because existing options were inadequate – especially because the subtransmission system needs both the ability to sectionalize the grid to maintain reliability when faults occur and because it demands advanced monitoring to quickly detect, locate, and respond to outages.
Historically, sectionalizing the sub-transmission grid has been handled by motor-operated switches that were insulated either by air or gases such as SF6. Because these products are mechanical devices, they require frequent inspection and maintenance. Not only does this put stress on already tight utility OPEX budgets and a workforce stretched thin by retirements, mechanical devices exposed to the elements can also fail.
Overhead recloser innovation drives desired and unexpected sub-transmission grid benefits
Development of the Viper-HV 72.5kV recloser took years, with significant input from customers and industry experts. But the advances made deliver important benefits to sub-transmission grid reliability and intelligence, along with improved costs. Indeed, the Viper-HV is a solid dielectric recloser that can respond quickly to temporary faults and deliver the sectionalizing the utilities originally requested, as well as serving as a creative alternative to circuit breakers and bringing reclosing capabilities where applicable.
Manufactured with a robust, proprietary, time-proven process, the Viper-HV recloser is made to solve several pressing sub-transmission grid reliability and cost concerns. For example, it is made to complete
a minimum of 10,000 operations without any need for maintenance – which delivers relief to utility OPEX budgets and frees up limited staff for other tasks.
Besides providing a low-cost, no-maintenance solution for sub-transmission grid sectionalizing, advanced reclosing technology is important for other reasons as well, including precise location of faults for rapid power restoration. One of the primary challenges facing utilities trying to restore power when there is an outage is finding the fault that caused it. Existing solutions can approximate the location of a fault which still requires utility personnel to devote precious time to pinpointing its exact location – often in harsh weather conditions – which results in longer restoration times and customer and regulator frustration. The Viper-HV overheard recloser can be equipped with controllers with built-in intelligence enabling precise fault location. The Viper-HV solution includes switching technology plus controllers to include not just impedance-based algorithms but traveling wave fault location determination, which is suitable on longer sub-transmission lines.
Rapid and less costly integration of renewables
Many nations are accelerating deployments of renewable energy to reduce greenhouse gas emissions and achieve ambitious decarbonization targets. Distributed energy resources (DERs) like solar and wind increasingly connect to the transmission and sub-transmission grid – especially when an extra transmission line is added to existing infrastructure to take advantage of an advantageous renewable energy location. DERs introduce complexity to the grid, including more frequent switching than is normal on sub-transmission feeders. The Viper-HV technology, since it was certified as a recloser with 10,000 operations capability, is more suitable than traditional motor operated switches.
Furthermore, the form factor of the Viper-HV recloser is easier to install than other solutions.
Removes need to add expensive and time-consuming grid infrastructure
Another significant benefit of advanced overhead recloser technology: it can avoid the necessity to add new substations. In cases when a new feeder and circuit breaker need to be added to a sub-transmission
system substation, the Viper-HV overhead recloser can increase the speed and lower the cost. That’s because traditional circuit breakers need to be ground-mounted on a concrete pad, which takes up space
many substations don’t have and involves permitting that can take a lot of time. By contrast, the Viper-HV overhead recloser can be mounted on the already grounded metal frames most substations have available. This takes no additional space and doesn’t require a time-consuming permitting process.
Advances in technology are essential for increasing the reliability and resiliency of the sub-transmission grid. At the same time, these technologies must lower, rather than elevate, the total overall costs including all aspects of the installation and lifecycle costs (i.e. maintenance, replacement). Sophisticated overhead recloser provides a budget-friendly option for enhancing reliability, resiliency, and helping to
green the power grid.
