One of the panels that I will be moderating this afternoon, on day one of Greentech Media's Networked Grid conference, focuses on the emergence of solid-state transformers. Though countless challenges exist, the advent of these new systems has the potential to be the most interesting story in the smart grid over the coming decade. The concept of solid-state transformers is not new (EPRI and traditional transformer vendors such as ABB, GE, Siemens and others have been researching this for years), but as with many other breakthrough technologies, timing may be everything. The industry seems to be witnessing a perfect storm of events that could finally take solid-state transformers from the R&D lab to live distribution grid circuit deployments in the next three to five years. What simultaneous industry events are occurring to help make this a reality?
1. The sheer availability and volume-based cost reduction of capable silicon carbide semiconductor components (MOSFETs and IGBTs). As an example, Cree (which is represented on today's panel) is currently working on bringing a number of these devices to market.
2. The shift from centralized to distributed power generation, and in this case, primarily the proliferation of distributed PV. When select circuits in the distribution grid reach 20% to 25%+ PV penetration, the potential for grid instability, the ability to effectively manage voltage regulation, etc., become real issues. I met with one major IOU recently that is capping the PV penetration on any given circuit at 15%, given these concerns. This is at odds with meeting RPS requirements, enabling renewables to scale, and the industry is actively looking for solutions, of which solid-state transformers may be one of several.
3. Power layer grid infrastructure and assets are largely monolithic and unmanageable. With these devices representing the true core of the networked grid, this makes little sense going forward, especially as nearly every other surrounding smart grid technology is taking advantage of embedded intelligence, network connectivity and remote manageability.
4. To a lesser extent today, but still a potential issue in the next three to five years and beyond is the growth of EVs and their associated load profiles. In some cases, the load of an EV can equal that of an entire home connected to a distribution transformer. I think you can see where this is going. Some IOUs are actually already doubling legacy transformer capacity in pockets of dense EV deployment. Though this is a viable band-aid solution right now, is it really the smartest approach going forward?
The promise for this new class of grid assets is immense, though so is the number of challenges that must be addressed in bringing them to market. Skeptics will ask many relevant questions. Can these devices be designed and manufactured to be cost-competitive with today's legacy transformers? Can a system based on solid-state electronics, presumably with a complex software control architecture, meet the efficiency and reliability metrics of existing, downright simple distribution transformers made largely with copper, iron and well-understood packaging techniques? These are certainly very fair questions, but as the industry starts to dig deeper into the functions performed by solid-state transformers, it will find that comparing them, metric-for-metric, with legacy transformers is ultimately comparing apples to oranges.
The industry needs to start thinking about these devices in an entirely different way, and that is not going to happen overnight. This is not transformer 2.0; it's an entire new class of grid asset that needs to be introduced to the market and positioned as such. It's going to take time and market education, as with any potentially disruptive technology.
Too often, when people first think about solid-state transformers, the initial benefit that comes to mind centers around footprint (size and weight). It's true that these new devices can reduce footprint by an order of magnitude, significantly helping with inventory management and operations costs (in many cases the installation cost of a distribution transformer is 10x the capital cost), but this is only the tip of the iceberg.
With the advent of solid-state transformers, voltage transformation (the primary function of a transformer to step up/down voltage) becomes only one of many new features. When you start to consider many of the other potential features surrounding voltage regulation (CVR, programmable output voltage, OV protection for PV-centric circuits, etc.), power quality (reactive power compensation and harmonic filtering), management and telemetry (integrated remote management, real-time load management, active line analysis, etc.), and other functions (such as the option for integrated storage), it becomes evident that these new integrated devices are much more than yesterday's transformers.
As you can see, comparing the capital cost of a legacy transformer with that of a solid-state transformer, with many more integrated features and embedded intelligence, becomes an uneducated comparison. Nobody that is serious about solid-state transformers is claiming they can be introduced to the market at the same price point of a traditional transformer, and the industry needs to start understanding why this is the case given the additional benefits (and associated systemic-level cost reductions) that can be realized. Beyond cost and features, true innovators in this market are also meeting efficiency and reliability metrics, that naysayers may be skeptical of, defined by the DOE.
Lastly, another important point to understand is that proponents of solid-state transformers are not suggesting a rip-and-replace strategy for existing transformers. The strategy for the introduction of solid-state transformers will center around strategic benefits related to the 'green circuit' of the future, rolling out devices on feeders with high PV penetration and EV load. In addition, most utilities have a relatively well-known annual replacement strategy (often in the 2% to 4% range) for aging transformers, failures, etc., providing another opportunity to introduce smarter devices, enabling a beneficial network effect as more devices are rolled out over time. The idea is to get the initial devices in place where pain points exist and then build a more intelligent platform over time. Also, international markets may provide significant greenfield opportunities where power quality is a major issue.
Despite advances in AMI and other early smart grid deployments, it's becoming clear that we are in the very early stages of a truly intelligent grid. Until the embedded intelligence of these higher-layer control plane architectures is integrated into grid assets sitting in the power plane, the grid is only partially intelligent. Although there are enhanced sensors and monitoring technologies being introduced into the power layer of the smart grid, it's only the beginning, as true real-time decision making and actuation is what will ultimately be required. Solid-state transformers, and the many additional features and benefits they bring, have the potential to be a cornerstone device for such functionality.
Attendees at The Networked Grid are looking forward to learning a lot more about this topic in today's panel, titled Distribution Grid 2.0: The Dawn of Solid State Transformers Enabling a Truly Intelligent Grid. In this session the audience will hear from, for the first time, upstart device manufacturer Gridco Systems, incumbent transformer supplier ABB, and silicon carbide component supplier Cree. In addition, Erich Gunther, Chairman and CTO of Enernex, will also be presenting many related topics in his groundbreaking technology workshop titled A Decoupled Power System Architecture: Any Voltage, Any Frequency, Any Time.