Thursday, August 18, 2022

A Grid Perspective: Flexibility from the Bottom Up, the Roots of Coordinating Distributed Energy Resources

By on October 29, 2021

(USDAgov on Visualhunt)

By Roberto D. Acosta, PE

There is not much to add about the critical infrastructure condition (a declared emergency now) of the electric grid at all levels; generation, transmission and distribution. The grid’s future is what worries me; what are we planning to do with the grid to keep Puerto Rico “healthy” and as an option for doing business? There is a worldwide discussion, a business transformation, on how energy will be generated, managed and utilized. The traditional centralized business model we have is not a sustainable model, we must embrace distributed energy resources (DERs) and Microgrids openly for a bright Puerto Rico. 

DERs and their balance in the current centralized system is an active topic where there is abundant information. For years now, the Power & Energy Magazine (PEM) of the IEEE Power and Energy Society has been publishing great articles on this transformation: “Harnessing the Full Potential of Clean Energy,” “Grid and Market Services from the Edge,” “Practical Microgrid Protection Solutions,” “Electricity Market of the Future,” “Zero-Marginal-Cost Electricity Market Designs,” “The Fragile Grid,” “Why Distributed? The Tradeoffs Between Centralized and Decentralized Resources,” and the list goes on and on. So why, with all the ongoing DERs integration research and help from agencies like the U.S. Department of Energy, could Puerto Rico not be a world-class case study with all the investment pending on the grid? Who is planning for the future? 

There are Grid Services that must be provided to keep the grid operating. Like in most countries, those services are not present in the Puerto Rico Electric Power Authority (Prepa)/LUMA Energy bills. Those who have Grid-Tied Photovoltaics (PV) know that when the grid is not present, regardless of how many PV Modules they have, their home will be without electricity; that’s why batteries are so popular now after Hurricane Maria. Knowing that any entity/individual investing to provide those grid services will require a return on investment (compensation), on April 16, 2020, I requested the Puerto Rico Energy Bureau (PREB) a tariff modification to account for grid services. Furthermore, I requested the PREB to put an end to Pepa’s biggest scam, the charge of the Proportional Fee (“aportación proporcional”) where you have to build the infrastructure and “donate it” to Prepa or pay a fee for improvements that never took place. Today, still not a single response from the PREB. 

There is about 200 megawatts (MW) in residential PV in Puerto Rico, and the PV penetration is strong and will keep increasing. The issue with PV is that the lack of planning is making the grid unstable and thus weaker (Yes, it could be worse!). PV, like most renewables, are intermittent, so imagine a sudden drop on PV generation because of a cloud. By now, all Puerto Ricans know the old central power stations could collapse on that power swing and create another total or wide-area backout. So what can be done to overcome this? By allowing the requested tariff change, all the individuals who have installed batteries could keep the power flowing or even support a central power station interruption by exporting power from their batteries and prevent a grid disruption. So, if Palo Seco or any central station is “lost,” again…, the grid frequency will start dropping, and all inverters will export more power (actually faster that any pecking / traditional unit) while other generating stations get online (this is the old droop operating mode); and if the fault is so big that could not be controlled, the several microgrids will get islanded (disconnected from the grid) and keep its operation (the resiliency goal of a system with DERs). Several years ago, the power experts at Prepa created the Minimum Technical Requirements Standards that covered many of the aspects of what is required. But they were applied for large projects, ignoring that thousands of residential projects would be much larger than a power plant. So why does Puerto Rico lack a structure that prevents PV penetration from making the grid unstable? (Well, I do not have a rational response to that). With a kind of urgency, Puerto Rico needs to adopt a plan that makes today’s DERs adoption (at any level) the roadmap to the future grid. 

Even today, we could see immediate benefits of this proposed plan, as the whole world is doing. Instead of hearing again when there is a power disruption that “the lack of maintenance and critical state of the centralized power plants and the whole grid will take time,” like if the blackout was unavoidable (“such is life”); now the Prosumer (residential, industrial or commercial) could either control their demand or export power to keep the grid operating and get an economical benefit out of it. With about 200MW on residential renewables and about 300MW of industrial load/standby generation, the grid Prosumers’ response is much larger than any central power station in Puerto Rico to stabilize the grid and prevent power interruptions. 

I must admit I am frustrated with the direction the electrical energy sector is going and come close to having a panic attack when I imagine this being a plot to pay the Prepa debt at a higher rate, as an obsolete business model like Kodak on the film vs digital camera. There is a bright and exciting future for this industry; a transformation of the industry and a convergence with the transportation sector with the adoption of electric vehicles. 

The grid issues we are experiencing today are just the tip of the iceberg. A “storm” may be approaching if we do not act promptly. The 100 percent renewable dream legislated for 2050 cannot end like the saying, “A Dream without a Plan is a Nightmare.” For now, I will try to stay optimistic; at least I got a title from the latest PEM, “Flexibility from the Bottom Up, the Roots of Coordinating Distributed Energy Resources”; keep working islanded and stressing to build a robust energy sector to secure our future, it is a collective one! 

– Roberto D. Acosta is the CEO and director engineer of Mayagüez-based Accurate Solutions Corp.. He earned his master’s degree in electrical engineering science from the University of Puerto Rico, Mayagüez, and his research interests include the industrial applications of distributed control systems, supervisory control and data acquisition (Scada) systems, motor control, energy management and power electronics. 

Accurate Solutions provides products, solutions and consulting and design services on automation hardware and software, electrical systems, process control, industrial communications, machine design and fabrication, motion control and control panel manufacturing.

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