There's a solution for that substation riddle just waiting for acceptance.
Edgy technologies: Some people may call them wild ideas, while others may consider them outrageous or even outlandish. Urban Dictionary defines edgy as “pushing the envelope, to be way out there, to be on the cutting edge.” Edgy technology takes many forms. Some of these are old technologies with a new twist, others are state of the art, and a few are still on the drawing board but poised to shake things up.
Consider some of the renewable energy technology advancements in the news lately. Roof shingles are available with photovoltaic (PV) characteristics that make each of them into mini solar panels. Developers are field testing clothing with built-in PV capabilities to power the devices people carry around with them all day. Research with spray-on PV coatings is underway, turning any correctly oriented surface into an electricity-producing resource.
This same type of process is at work in the electric industry's technology progression, and the electrical substation has been the epicenter of this development for many years. It wasn't too long ago when the metal-oxide surge arrester was considered edgy, radical and uncomfortable. The idea that insulation levels could be reduced by using some device with zinc hockey pucks in it was extreme and unsettling, but today, no one thinks twice about the practice. Progressive change is driving technological evolution, which is bringing about improvements in the way the substation performs.
Improved insulation levels have led to compact substation designs, which are gaining acceptance worldwide as utilities face the challenge of providing substation capacity in urban settings with limited available space. By combining advanced technologies with materials having improved characteristics, manufacturers now offer compact apparatus. This enhances air-insulated substation (AIS) designs, making them more compressed than ever before.
These enhanced AIS designs use technologies such as optical instrument transformers, pantograph type and bus bar disconnectors, and reduced phase spacing, achievable by application of improved metal-oxide arresters reducing insulation levels. They also use sulfur hexafluoride (SF6) circuit breaker designs that are pretty edgy. ABB's disconnecting circuit breaker and Siemens' Simobreaker offer a technology mix by incorporating disconnect switch capabilities with the breaker. Siemens' Simover breaker, also known as a pivoting circuit breaker, has the instrument transformer, a rotating disconnector and the breaker all in one assembly.
There also are hybrid substation designs combining gas-insulated substations (GIS) with AIS technologies, shrinking the substation footprint further. They're a mix of open-air apparatus and SF6-enclosed switchgear. These hybrids offer an economical alternative to the pure GIS approach for locations that are somewhat smaller than required for an AIS facility but large enough for a hybrid substation. Today's substation designer has many more options and tools than were previously available.
Another force with the potential to change the way substations are configured is the high-temperature superconducting (HTS) technology. HTS has been used for many years, but those installations have been limited to pilot projects designed to test the application in the grid. These applications include superconducting magnetic energy storage (SMES), HTS cable and HTS fault current limiters installed on utility systems.
One of the latest U.S. Department of Energy (DOE) pilot projects is on Southern California Edison's (SCE's) grid. SCE will install a HTS medium-power transformer in an Irvine, California, U.S., substation. The HTS transformer is rated 69/12.47 kV, 28 MVA and will incorporate fault-current-limiting capabilities. The project is a partnership between the DOE and industry. DOE is funding the project. The industry's team is made up of Waukesha Electrical Systems, Oak Ridge National Laboratory and SuperPower Inc.
The HTS concepts have been tested and proven to be reliable but one of the drawbacks to deployment is the cost. So far, each installation requires a cryogenic support system, but what happens if there is a consolidation of cryogenic cooling? There are proposals to build a superconducting substation using all the different types of HTS apparatus but with one cryogenic cooling system for the entire substation.
Researchers think a superconducting substation would be more efficient since it would be virtually lossless. The HTS substation would have a higher reliability with reduced maintenance because of the enclosed design. It also would have a much smaller footprint — up to a 70% reduction — and a higher safety level. This certainly fits into the definition of an edgy concept built with edgy technology, but it's going to take time to convince the skeptics.
It's not just outdoor hardware moving into the technological crosshairs. A couple of years ago, Seattle City Light (SCL) took an innovative approach to redefining its substation's control system. SCL replaced its centralized remote terminal unit (RTU)-based substation supervisory control and data acquisition (SCADA) system with an Internet protocol (IP)-based communications system. It offers more information and flexibility than traditional SCADA systems.
The SCL system used a substation server consisting of a Schweitzer Engineering Laboratories SEL-3354 substation computer running SUBNET Solutions' Substation Server and Substation Explorer. It also used GarrettCom's switches connected to intelligent electronic devices (IEDs) interfacing with substation equipment.
Integrated IP-based substation control technology is here to stay and growing in applications. Cisco and Alstom recently announced they have formed a partnership to integrate this end-to-end IP network with substation equipment and control systems. Their partnership combines Cisco's grid-hardened routers and switches with Alstom's power apparatus such as power switches, protective relays, capacitors and the digital control systems that keep them all operating. Alstom is embedding Cisco's IPv6-capable platform in its substation gear to ease the transition from serial SCADA communications protocols to true IP-enabled smart grid communications.
With this transitioning, what happens when the landline Internet connection is lost? Well, service is lost, which can disrupt everything, but another 21st century technology is coming into play. Internet connections through satellite are independent of landlines. Satellite allows utilities to keep their entire system on a single network, which is a huge advantage when making revisions, modifications and upgrades.
Taking this another step further, the satellite can be used for other services such as streaming video for security purposes, phone service using voice over IP and faxing. It all can be done at the same time, improving efficiencies.
Power electronics devices have been widely used in the electricity industry for years. High-voltage direct-current (HVDC) systems and flexible ac transmission systems (FACTS) have become commonplace. Research is taking place to apply power semiconductor technology to solid-state circuit breakers and transformers.
Many point out the performance of the semiconductors would have to be greatly improved for this application, but that's happening. Progress is being made in developing a DC solid-state circuit breaker. ABB is working on a hybrid design using semiconductors with mechanical disconnectors for the HVDC grid being proposed in Europe.
The solid-state transformer also is gaining traction in the research world. A solid-state transformer is not a dry-core transformer, it is a voltage converter without the classic iron, steel or copper typically found in such a device. It's referred to as a digital grid router by many of those involved with the research. That may sound pretty far out, but the concept is sound.
In Japan, the nonprofit Digital Grid Consortium was formed to develop this solid-state transformer. The group consists of ORIX Corp, NEC Corp. and National Instruments. There are rumors of several Japanese electrical equipment manufacturers planning to join the consortium in the future.
The consortium reports the device will replace today's coil-based designs with solid-state AC-to-DC-to-AC converters. It is feasible with today's technology, but the expense has limited this to research rather than pilot project until breakthroughs in semiconductor technology improve the economics.
Ever noticed birds, snakes and squirrels cannot read? No matter how many “Danger High Voltage” signs are put up, these creatures keep coming in contact with the energized bus and equipment, knocking out service. Several high-tech applications are available to help with this issue.
Composite poles and structures are finding their way into the substation. Granted, it's slow, but it's happening. Shakespeare Composite Structures has developed bus and switch supports for substation applications. Shakespeare points out these pesky critters can hop on the fiberglass supports with a much lower possibility of shorting to ground and causing an outage. The 50-year-old fiberglass and composites technologies are considered cutting edge, but it has taken time to get them into the substation.
Another innovative abatement method comes from TransGard. It has developed an interesting approach to deterring creeping, crawling and slithering critters by using energized fencing made up of specialized panels. The panels are installed around the equipment the utility wants protected. Rochester Gas & Electric installed this system in all of its substations and saw animal-caused outages drop to one in recent years (see T&D World, Electric Utility Operations, August 2012).
Feathered creatures are a little more complicated but many products are available. Bird-B-Gone, for example, offers misting systems and plastic spikes. But one product drips of cool technology: It's a system that uses sonic technology to play more than 22 different species distress and predicator calls at randomly selected times and durations. With this variety, the birds do not hear the same thing over and over. Rather, it makes them edgy, and they head for what they perceive as a safer place.
Linking the Substation
A wide variety of IEDs, microprocessors and other high-tech devices are built to operate with optical, wireless and Ethernet technologies in today's substation. These devices can multiplex data from multiple sensors on digital communications links and use the data at the substation level.
Many utilities are finding it a challenge to link internal and external substation equipment because of connection methods. In the past, hardwiring was the technology of choice, but fiber-optic cables are changing traditional concepts. They also are a more cost-effective method for connecting IEDs, sensors and monitoring equipment than copper control cables.
Hardwiring control circuits is an extremely labor-intensive task with each control wire individually connected to the system by a technician. Hundreds of hours are spent making the connection diagrams, installing the cable, wiring the devices, testing those circuits and recording changes on as-built drawings. It worked back in the day with large workforces, but in today's environment, resources are limited and need to be used wisely.
Ethernet switches acting as uplink ports allow for high baud rates, which increase the speed of the data transfers essential for linking controls, protection and equipment together. Data paths can be of several types — such as command and control paths, data monitoring paths and generic data transfer — that can be archived or purged as needed by the system.
Multifunctional protection and control devices using soft logic coupled with fiber-optic cables simplify and speed up the whole process and require much less labor. In addition, using fiber-optic cable has several intrinsic benefits. Fiber is immune to electromechanic interference, allows IEDs and sensors to be located at extreme distances, has the ability to multiplex many sensors over a single optical fiber and is easier to install.
Change is certain in today's high-tech world and the electric industry has to change with it or it will be out of date and get left behind. Engineers are always under pressure to save money, improve designs and build more efficient systems. As the industry pushes the limits, it's important to take advantage of all technology has to offer — even the edgy.
Technology is continuously maturing, developing and advancing, which, in turn, drives apparatus performance and quality. Manufacturers are continuously introducing new applications for digital controls and communications systems. Today's substation is modern, but tomorrow's engineers and technicians will wonder how the industry was able to meet the demands for electricity with such antiquated equipment.
These technological advancements are inspiring creative minds to come up with the next generation of substations. In the early days, the substation engineer was limited by the tools available, but today is a different story. We are more limited by what we are willing to accept. The industry no longer has a tool bag but rather a tool chest at its disposal.