Drawing of renewable power system with wind turbine, transmission tower, house and electric vehicle

Grid Modernization: Opportunities and Obstacles

The main goal is still flexibility to adapt to the new technologies in the grid.

Grid modernization has become a catch-all phrase to refer to changes needed in the power grid to accommodate all the rapid technological changes happening in the generation, transmission and distribution of electric power. In particular, grid modernization often implies the increasing application of sensors, computers and communications, that is, increasing the intelligence or ‘smarts’ of the grid but the main goal is still the flexibility needed to adapt to the whole range of new technologies in the grid.

Here is a list of various broad technologies to watch.

The Changing Generation Mix

Although everyone’s eyes are on the rapidly increasing solar and wind energy resources, the big story in recent years is the replacement of coal generation plants with natural gas turbines, a trend that is surely to continue in 2019. Fossil fuels still produce about 60% of US generation but now that natural gas has surpassed coal as the leading fuel, the carbon emissions are decreasing. The increased production of natural gas by fracking has made this fuel cheap and the gas turbine technology is well understood and quickly constructed.

Two well-known non-carbon technologies, hydro and nuclear, still produce about 27% of our electricity but no new plants are being constructed, for various reasons, and cannot be counted on to be part of the future solution to greenhouse gas reduction. So in 2019 there will be continuing focus on increasing solar and wind installations. Other sustainable resources are less developed, so the emphasis is on wind turbines whose technology and economics are well understood, and on photovoltaics whose cost reductions have made it increasingly more attractive.

Renewable Generation – Including Storage

The intermittency of sun and wind poses a significant operational problem and it is well understood that the only way to make large penetrations of solar and wind feasible is to introduce methods of storing electrical energy. The focus is on the more flexible options like batteries and fuel cells which can be located almost anywhere and not on the more known technologies like pumped hydro because they are geographically constrained. The battery technology continues to make steady progress both in technical performance and cost but despite the vast expenditures in R&D, especially in the electric vehicle (EV) sector, major breakthroughs have not happened to dramatically change the cost-benefit ratio.

Despite that, 2019 should see a rapid growth in people adopting EVs although not as much as the optimists predict. A major challenge is the slow development of the charging infrastructure, both for the fast-charging stations needed on the highways and the distribution feeder/transformer retrofits needed to handle the home charging loads. Although the main motivation for EV is to replace petroleum exhaust with non-carbon resources, this is completely dependent on the generation resource mix, the majority of which is still fossil fuels.

The topic of the day will continue to be the generation mix and how rapidly distributed energy resources (DER) can be used to replace fossil fuels. The fundamental challenge for DER is that of geography — not all regions are blessed with solar, wind or even hydro, as these resources are spread unevenly around the country. Any shift in the generation mix will absolutely require transmission lines to get wind power from the Midwest and solar power from the Southwest to reach the load centers dependent on fossil sources.

Sensors, Communications, Computers

The grid is spread geographically across continents as well as vertically across several voltage levels (from 120/240V at the user level to 765kV transmission). To monitor and control this complex machine is a difficult task and would be impossible without the proliferation of sensors, communications and computers in all parts of the grid. In the past, it was possible to reliably manage the grid by only measuring the central power plants and the highest voltage transmission. With generation sources now being widely distributed even at the lowest voltages, the decreasing cost of communications and information technologies (CIT) is now making it possible for closer monitoring and more automation.

Because the central generators and transmission were reasonably well monitored, the focus now is at the distribution level. Watch for more distribution automation in 2019 with many of the distribution management functions being further bundled into the Advanced Distribution Management Systems (ADMS). The management of the Distributed Energy Resources (DERMS) is getting more attention as these generation resources proliferate and directly affect the performance of the grid; the ‘duck curve’ in California has highlighted the negative impact of solar generation ramping, much of it being customer-owned and thus unobservable to the grid operator. Watch for significant activity in this general area of distribution automation in 2019 although it does not attract as much press coverage as the increasing solar and wind resources.

Grid Operation and Controls

Although the number of sensors, communications and computers are growing exponentially, utilizing these for actual applications that can help the operator make decisions or automatically take operational actions have come slowly. The quantity of historical measurement data from synchrophasor measurements (PMU) and customer usage measurements from AMI data is increasing exponentially and engineers are only scratching the surface in digesting this data into usable information for design and planning. Of course, the greatest potential is in the use of this data in real time to help the human operator or to initiate control and protection actions.

There are already many one-of-a-kind special protection and control schemes (i.e. fast controls) that use PMU data as input and take advantage of the high bandwidth communication and fast computers to enable the fast controls. There are also experimental schemes to use AMI data to do better voltage controls on the distribution feeders. Watch for EMS/DMS vendors in 2019 to announce such new controls as standard products. In addition, the user interfaces for the EMS/DMS operators are being upgraded to show distillation of such data; for example, in those transmission systems susceptible to slow oscillations, the EMS display can show the damping of certain oscillation modes calculated from PMU data.

Power Electronics

The proliferation of non-synchronous generation and storage devices mean that power electronic devices on the grid will also proliferate. On the one-hand these devices increase the complexity of operating the grid but it also provides new dimensions of controllability as each power electronic device can be specifically designed to control all the output variables. This is an opportunity that can mitigate some of the systemic difficulties that are expected from all the new types of generation and storage. For example, these devices can compensate for the lack of reactive power sources by providing four-quadrant voltage control or compensate for the lack of inertia in a non-rotating source.

 

Up to now most power electronics have been designed to connect the generation/storage device to the grid and the focus has been on meeting interconnection standards. However, the power electronic vendors are starting to see the potential of providing control (ancillary services) to the whole system rather than just their own device. In addition to the applications dependent on measurements, communications and computers, watch for the power electronics being increasingly included as part of these ‘smart’ controls.

Resiliency and Cybersecurity

Ever since superstorm Sandy in 2012 that blacked out Manhattan and surrounding areas, the ability of the grid to withstand and recover from major natural disasters have become major concerns. Ever since the hacking incident in Ukraine that led to extended power outage, the spectre of a cyber-attack on the grid, especially aided by state sponsorship, has become a major national security concern. Two issues remain unresolved: one is that we need a broader range of technological defenses like better restoration tools after a storm or better detection tools against cyber-attacks; the other is a consensus on what is the prudent level of defense at what cost.

Watch for extensive activity in both these areas. The Department of Energy has already announced plans for significant R&D expansion in what is being called the ‘Resiliency Model’ as part of its Grid Modernization Initiative. Also, NERC/FERC is actively engaged in upgrading the reliability standards to increase resiliency against natural disasters and enhance cyber security. However, progress in this area in terms of actual implementation will be slow as both consensus and investment will be needed.

Government Policy

The business of distributing electricity is regulated by the state while interstate transmission is regulated by the federal government. Moreover, the grid is so integrated into the fabric of society that government policies on environment, commerce, defense and homeland security all affect the decision-making on the modernizing the grid. In the U.S., government policy has strongly motivated the growth in solar and wind generation but even then, the economics — cheap natural gas — has been more instrumental in shutting down coal plants than the renewable resources, at least in the short run. Similar to encouraging non-carbon generation, modernizing the grid is needed to enable this shift in the generation mix, and government policies are needed to encourage this. The investments needed for grid modernization are not always evident to the state regulatory agencies but without it, the greater good of limiting greenhouse gases will not be possible.

Global Perspective

Just as the change in the generation mix varies between regions, these variations are even wider between countries and continents. In the developed countries of North America and Western Europe, load growth has been very slow, so new investments in carbon-free generation or smart technologies will likely increase the cost of electricity. For developing countries like China and India, load growth is expected to be high, so revenues can be expected to rise to offset new investment, but keeping up with the load growth means that India and China cannot start ramping down on greenhouse gases until the 2030s, even though they will also be building renewable energy sources faster than all other countries. Thus the motivations, opportunities and obstacles in modernizing the grid will vary widely across the globe, resulting in not just different cost structures but also energy policies, grid regulations and R&D expenditures.


Anjan Bose is a member of T&D World's Executive Insights board.

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