How to rebuild the grid in Puerto Rico

Ross Baldick ConsultingHurricane Maria has caused huge damage in Puerto Rico, particularly to infrastructure such as the electricity system. My sincerest sympathies go to everyone there, both in PR and in other regions. As my previous work on electricity network interdiction suggests, repair of electricity networks can depend significantly on the long lead-times to order and build extra-high voltage and high voltage transformers. As Puerto Ricans begin to restore services such as electricity, an issue that should be considered carefully is the desired end-point for their replacement electricity infrastructure and whether they should effectively rebuild their previous network or build according to a new design.

Most expansion of transmission networks, and most repair situations, involves adding or replacing equipment in an existing network. This significantly constrains the sort of solutions that can be accomplished.

However, PR is faced with a rather different problem. Although I am not personally familiar with the full extent of damage, the reports in the press suggest significant destruction of most of the network. Repair back to the state prior to the hurricane may involve rebuilding essentially everything. Under such circumstances, and given that future hurricanes may be at least as destructive to a conventional electricity system, it is prudent to step back and consider alternatives.

As an example of an alternative, perhaps a more distributed structure that plans for distributed renewables would be a better approach. Existing electric distribution networks are typically limited in the amount of distributed generation they can integrate. In the mainland US at least, the limits are typically not due to the distribution line capacity itself, but to things like “protection schemes,” typically using fuses, that were designed with the assumption of one-way flow toward consumers. In an existing system, upgrading to allow for net flow from the distribution system into the transmission system can require significant incremental investment to replace protection systems. For a system being fully built from scratch, however, it may be possible to incorporate more flexible protection systems from the start.

This and other issues should be considered carefully before large amounts of money are spent in PR on rebuilding a system according to a design that has already been shown to be vulnerable to the next hurricane.

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Smart grid: let’s not throw out the baby with the bathwater

Despite the end-of-school-year mania, I managed to get away to  the 2017 IEEE Innovative Smart Grid Technologies conference in Washington, DC, in late April, to talk about the Smart Grid grad course that I was wrapping up at UT. I participated in a panel, “Innovations in Smart Grid Education,” chaired by Dr. Kenneth Lutz of the University of Delaware, with participants from MIT, the University of Illinois at Urbana-Champain, Wichita State University, and Clemson University.

I talked about the Smart Grid grad course I taught at UT this semester, making the point that “smart grid” discussions in practice are often focused on the distribution system and end-use, despite typical definitions in the literature being more general. I took an expansive definition in this class, including transmission and generation, for example, which also allowed me to invite colleagues from ERCOT and Oncor to participate.

Why do I use an expansive definition in my pedagogy?

Because the phrase “smart grid” implies that the existing grid is stupid. In fact, for many years in North America and elsewhere, operation of the transmission grid has been incredibly sophisticated — far more sophisticated than any other infrastructure system I’m aware of.

When we focus only on making the distribution grid smart, we risk throwing the baby out with the bathwater, by not building on the existing smarts in the transmission system.

In terms of pedagogy, this means students need to be aware of the entire grid, both smart and not-so-smart, in order to avoid a skewed perspective on the electricity system. As we look toward solving problems such as integrating high levels of distributed solar PV, we need to remember that the existing transmission and generation system provides the foundational infrastructure.

Click here to download my full presentation.

Highlights of the course include an overview of architecture of the smart grid, the generation and transmission system, distribution systems, and end-use. The strongest common theme: we are all searching for a good textbook!

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Pumping water uphill: storing energy without batteries

Ross Baldick Electric Power Consulting

Jaime Luengo shows UT professor Gary Hallock how the solar-powered water pump works.

It’s been my pleasure for the past several years to supervise a senior design project in my Electrical and Computer Engineering department at The University of Texas at Austin. The project is aimed at avoiding battery storage in off-grid solar applications by taking advantage of the storability of the final product or service provided by an electric motor.

Think of an electrically-driven water pump that is filling a raised tank, with the water then being used for domestic or agricultural use by letting it flow downhill. If the pump and tank are sized appropriately, then the pump could operate when power is available and still pump enough each day to cover the needs.

Our team’s approach to powering this system from the sun without battery storage has been to use a variable-speed drive for an electric motor and vary the drive frequency to match the power output from a solar panel. When the sun is shining brightly and more power is available from the solar panel, we adjust the drive frequency up so that the motor can use all the power. When it is cloudy and the solar panel produces less power, we adjust the drive frequency down so that the motor is still pumping, but at a lower rate, and using the available power. By adjusting the drive frequency this way, we can utilize whatever power is available from the panel without battery storage. We are storing the energy by pumping water uphill.

Ross Baldick Electric Power Consulting

This year’s senior design team included (left to right): Carly Stalder, Ankit Sharma, Ji Hoon Seon, and Max Granat. Not pictured: Jaime Luengo, Cody Scarborough, Schuyler Christensen.

(There are other potential applications, such as-available air conditioning or other mechanical loads where there is inherent storage in the end-use product or service.)

Several senior design groups have been working toward this goal over the last few years. This year the students really came together and were able to build on previous groups’ efforts to build a working prototype that could harness variable light levels.

These photos show you the results: a working prototype that pumps more when the sun is bright.

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Pathways to decarbonization: ZECs, DERs, and inertia

Ross Baldick Consulting

Brad Jones (left) and Ross Baldick at the Austin Electricity Conference.

Decarbonization was the theme of the seventh annual Austin Electricity Conference, held April 20 and 21 by the UT McCombs School of Business, Cockrell School of Engineering, LBJ School of Public Policy, and School of Law.

As the name implies, decarbonization entails shifting the fossil fuel mix toward less intense producers of carbon dioxide together with reduced reliance on fossil fuels for electric generation over time. Our questions: How to implement a zero-carbon grid from a legal and policy perspective? How to achieve it from a technical perspective?

It was my pleasure to introduce keynote speaker Brad Jones, who has been an electricity industry executive for more than three decades. I first began to know Brad closely when he was Vice President for Generation Development at TXU. We  disagreed on whether to implement the nodal market, and I remember his graciousness and intelligence during that debate. He then became Vice President for Government Affairs at Luminant, the successor generation firm of TXU. He joined ERCOT as COO in 2013 and in 2015 became President and CEO of the New York ISO (NYISO), which operates the state’s wholesale electricity market and is responsible for its bulk electric system reliability.

Lower carbon dioxide emissions, green technology, and renewables, Jones said, have become front and center in New York, even making it into the headlines of The New York Times. At the NYISO, priorities include decarbonization, integration of high levels of renewables, and creating a two-way grid. The state is introducing a requirement for electrical load-serving entities to purchase zero emissions credits (ZECs) in proportion to their statewide load, with proceeds going to eligible nuclear power plants. This provides market-compatible support for nuclear generators that values their zero carbon emissions, complementing analogous schemes for renewable resources. He emphasized that ZECs are designed to be a bridge to the future, and that New York is not expecting that ZECs will be needed forever. The state, in other words, is acknowledging the social cost of carbon.

Jones also discussed distributed energy resources (DERs). We need, he said, to value the contributions of DERs, by: 1) facilitating compensation through transparent pricing and metering, and 2) offering financial credit for reducing the load on distribution systems.

Jones concluded by emphasizing the need to internalize a carbon price into the wholesale market. That price will help to do two things. First, to guide operational decisions toward existing low-carbon resources. Second, to guide capital decisions — such as building more low-carbon generation in New York and building new transmission to bring Canadian hydro power to the state.

Brad Jones (left) and Ross Baldick at the Austin Electricity Conference.

On my panel, “Managing the Decarbonized Grid,” we discussed the technical challenges of operating an electricity grid with low or zero emissions. I emphasized that these challenges depend on the mix of resources used. (Click here to download my introduction and the panelists’ introductory remarks.)

For example, our main path to decarbonization in recent years has involved renewable resources such as wind and solar, which are generally connected to the grid via power electronic converters. Power electronics interfaces have a crucial difference with traditional grid-connected rotating machinery in that they do not “natively” provide inertia. Inertia has been essential in the control of the electricity system since its inception, because it enables stable synchronization of the electric waveforms in the grid and serves to limit the rapidity of changes after a disturbance. In order to decarbonize with renewables, we need to deal with this reduction or elimination of inertia.

One solution is to utilize the renewable resources to “synthesize” inertia using the flexibility of their power electronic converters; however, the drawback here is that some of the renewable production is sacrificed. A second solution, being developed and tested by panelist Brian Johnson of the National Renewable Energy Laboratory in Golden, Colorado, explores controls for power electronic converters that do not rely on inertia to provide synchronization.

Click here to access all four of the conference panels.

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