To take advantage of today’s smart grid capabilities, the electrical industry must establish new criteria for switchgear. Smart grid-era switchgear needs to be more “digitally intelligent,” flexible, compact, and able to withstand harsh environments.
But the industry is by nature conservative and slow to adopt change in its technology, including medium voltage (MV) and high voltage (HV) switchgear.
Why is that? Technological innovations surface about every 20 years, but switchgear can last as long as 40 years as a valid architecture for traditional, centralized power transmission and distribution (T&D) networks. What’s more, T&D operators require stability, which may make them hesitant to enact changes. Then there’s the learning curve: Maintenance and repair of such long-life devices is easier for service crews if there is no change in technology.
With those factors in play, it’s not surprising that some utilities face challenges in adapting their switchgear to meet smart grid requirements.
Smart grid basics
Smart grids have two main objectives:
• Optimize the balance between the demand and supply of energy
• Integrate more distributed and renewable energies
Meeting these objectives means deploying digital technology that allows for two-way communication, between the utility and its customers, and between devices along the transmission and distribution network and the network operations center. However, much of today’s electrical infrastructure, including switchgear, enables only the simple one-way flow of communication valid for centralized energy production.
Image 1: Modular 2SIS switchboards offer the greatest flexibility to accommodate smart grid applications
MV switchgear and smart grids
While the physics of switchgear remain basically the same, the technology is changing as well as the way to optimize it for the smart grid. By examining the characteristics of a smart grid network, it is possible to gain insight into how switchgear can meet this challenge.
• Smart grids include more circuit breakers in the network. Adding circuit breakers in distribution network loops is an efficient way to decrease the number of customers affected by an outage and to reduce the time it takes to restore power.
• Remote control becomes vital. Switchgear with remote control and monitoring features are essential to two-way communication, feeder automation, and self-healing networks, as well as optimizing loads along the distribution network. The best approach is to upgrade MV/LV substations by implementing remote-controllable MV switchgear whenever possible.
• Low-consumption sensors and digital meters enhance control and monitoring.Compact low-power current transformers (LPCTs) and low-power voltage transformers (LPVTs) can replace heavy traditional CTs and VTs. Today’s LPCTs offer innovative current sensors that allow greater degree of control and monitoring along the protection chain. In addition, a real-time view of the available power is crucial in smart grid applications and will require installing more power meters associated with the sensors.
• Modularity is essential. MV switchgear will become more distributed throughout the smart grid network, and modular switchgear will meet the need for flexibility.
As smart grids evolve, digital intelligence will allow utilities to view, measure, and control what’s going on along the network. Remote control, which depends on digital intelligence, can optimize maintenance and avoid costly manned field service visits.
With more renewable and distributed energy sources integrating into smart grids, monitoring and measurement will become crucial to the ability to balance supply and demand.