Home Energy Solar Power Reporting in from California's Distributed Energy Future
Reporting in from California's Distributed Energy Future
David Herron March 8, 2017 March 8, 2017 Solar Power, Wind Power
The electricity grid is facing an interesting challenge: Solar and Wind energy is catching on faster than expected, forcing a rapid change change in how the grid operates. It's extremely excellent that renewable electricity is growing so quickly, and in many places is directly cost competitive with fossil fuel electricity. The problem is that solar and wind are intermittent energy resources, and while electricity from solar is beginning to obliterate the need for fossil fuels during the day, the utility companies have to quickly ramp up non-Renewable electricity production to supply evening electricity needs.
That's what the picture above shows. In the industry this is called The Duck Curve because of you squint your eyes right it kinda sorta looks like a duck maybe. The problem is the steep ramp-up of fossil fuel electricity as soon as the sun sets in the evening.
It seems the destined role for wind and solar is in providing a huge portion of our electricity needs. That intermittency problem must be solved. In California, and some other locales, the solution to that problem is to completely remake the electricity grid. The goal is a cooperatively operated collection of distributed energy resources (DER's) owned by multiple companies, that together keep the electricity grid supplied and functioning.
This week I'm attending a Greentech Media conference: California's Distributed Energy Future. California is leading some interesting work in this area, and has an extremely aggressive agenda. Today's presentations were a kind of introductory tutorial on what's happening, given by people closely involved with the CPUC (California Public Utilities Commission), the agency leading the implementation of these changes. One speaker, a former high-level CPUC staffer, described the change as transitioning DER's from being "accommodated" by state policy, to being relied upon as a Grid Resource.
DER? I've used that acronym a couple times and it's worth giving a definition: DER === Distributed Energy Resource. Being "Distributed", DER's are spread around the grid rather than being centrally located like a traditional electricity plant. Being Energy Resources, they can be anything that can operate as a grid resource performing tasks useful to the electricity grid. They can be a solar array or wind turbine, pumping electricity into the grid. Or they can be an energy storage unit, absorbing electricity or else releasing electricity into the grid as needed. Or they can be electric cars, or any of the large scale electricity consumers like welding shops, or even traditional electricity generators.
Traditionally we've had a centrally owned and operated electricity grid. The electricity came from huge resources, a coal or natural gas fired turbine plant, or a hydroelectric dam, or a nuclear reactor, each of which would contribute 100 or more megaWatts of electricity to the grid.
Another conference speaker defined a DER as a "Demand Side Power Plant". "Demand Side" meaning located at where electricity demand occurs, in homes or offices or factories or whatnot. A solar array on the roof is a power plant, that's colocated with the place where electricity demand occurs. That electricity doesn't have to leave the premises, and can instead be consumed on-site.
As long as the total electricity generation of wind and solar remained a drop in the bucket, utility regulators could give them space to operate, let them pump some electricity into the grid, but the real action was with the traditional electricity plants. That's changing, quickly. For the last several years the vast majority of new electricity generation installed in the U.S. has been wind and solar. In some places that Duck Curve effect shown above is already happening.
Renewable energy resources can no longer remain small and sidelined, accommodated by regulatory policy. These resources are becoming so significant that regulators have to pay attention, and have to change how the electricity grid is managed.
The industry recognizes this fact. One of the key documents about the implementation of computer/network protocols to implement the distributed grid IEC's Technical Report #61850-90-7, Communication networks and systems for power utility automation Part 90-7: Object models for power converters in distributed energy resources (DER) systems, had this to say:
DER systems challenge traditional power system management. These increasing numbers of DER systems are also leading to pockets of high penetrations of these variable and often unmanaged sources of power which impact the stability, reliability, and efficiency of the power grid. No longer can DER systems be viewed only as "negative load" and therefore insignificant in power system planning and operations. Their unplanned locations, their variable sizes and capabilities, and their fluctuating responses to both environmental and power situations make them difficult to manage, particularly as greater efficiency and reliability of the power system is being demanded.
At the same time, DER systems could become very powerful tools in managing the power system for reliability and efficiency. The majority of DER systems use power converters to convert their primary electrical form (often direct current (dc) or non-standard frequency) to the utility power grid standard electrical interconnection requirements of 60 Hz or 50 Hz and alternating current (ac). Not only can power converters provide these basic conversions, but power converters are also very powerful devices that can readily modify many of their electrical characteristics through software settings and commands, so long as they remain within the capabilities of the DER system that they are managing and within the standard requirements for interconnecting the DER to the power system.
The rest of that document is dry technical documentation data structures and commands for DER's to work collaboratively over a computer network. Such as over the Internet.
In other words, the Internet Of Things is reaching into the electricity system. The vision is for DER's to be connected to the Internet, through an ultra-safe communications protocol, allowing for distributed real-time monitoring and control. The goal is not just controlling import and export of electricity to/from a DER, but for the DER to provide what's called auxiliary services — to support stabilizing frequency or voltage or power levels on the grid, for example.
A key element of a DER will be a "smart inverter" that knows how to provide those grid support functions, and eventually will have communications protocols sufficient for it to participate in the distributed control system.
In California, it's envisioned the result will be an open market, or open platform, for a plug-and-play distributed energy grid.
This isn't being done because Internet Of Things is a cool buzzword and someone was playing with a Raspberry Pi in their basement. The goal is to orchestrate changes of electricity supply, electricity demand, so that the excess of daytime solar energy can be time-shifted to the evening. That could eliminate/mitigate the need to ramp up fossil fuel plants every day for evening electricity needs.
It just so happens that micro-sized computers have become so powerful that they're starting to be embedded in all kinds of things. That phenomena goes by the marketing buzzphrase Internet Of Things, and is much more than toys built with Raspberry Pi's. There are industrial-quality counterparts to the Raspberry Pi, which can be embedded in industrial equipment like solar inverters, giving those inverters much-needed programmability and Internet connectivity.
What would the electricity grid look like if you redesigned it to incorporate modern communications and computation capabilities?
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Jason_Jungreis
Nice write-up, hope you enjoyed the DER conference, and I'll be interested to follow your continued efforts in that space.
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