Puerto Rico Grid: Build Back Better

It has been hard for me to track the progress — or lack thereof — in bringing power back to Puerto Rico. It does not help that Puerto Rico is insolvent with some US$70 billion in debt and $50 billion in unfunded pensions.

I contacted several transmission and distribution companies who were more than willing to put boots on the ground and buckets in the air to help, but they also had responsibilities to their shareholders. One real issue in getting crews to the island was that Puerto Rico didn’t have signed mutual aid agreements that could be acted upon quickly; without them, utilities and contractors couldn’t take on the risk of performing the work and not getting paid.

We all knew there was something fishy with the Puerto Rico Electric Power Authority (PREPA) deal with Whitefish Energy. Richard Ramos, executive director of PREPA, defended his decision to sign a $300 million contract with this small Montana firm, but the lack of the resources at Whitefish meant the likelihood of pulling off the rebuild was low. Ultimately, Whitefish was not able to stand up under scrutiny, and neither could Ramos. The deal was cancelled, and Ramos turned in his resignation.

Now we are seeing considerable progress because one governor reached out to another. Gov. Ricardo Rosselló of Puerto Rico connected with Gov. Andrew Cuomo of New York. The state of New York responded aggressively to Rosello’s request for assistance, and the “Build Back Better” plan is now available. It has both short-term and long-term elements taking into account what is needed to stabilize and add functionality to the grid over the next five to 10 years.

The plan is not cheap, but it exists and it is actionable. It is designed to allow PREPA to move forward in stages as money becomes available.

The rebuild strategy is outlined with duties organized from short term to long term.

• Address diesel generators
• Supply critical loads
• Tackle intermittent power issues
• Build back grid to prior state
• Upgrade to best practice for new installations
• Upgrade to best practice for upgraded systems with the highest current standards for reliability and resilience.

The document also suggests that PREPA consider integrated resource planning as well as the impact of distributed energy resources (DERs) and islandable microgrids when building out the grid.

Two things strike me about this Build Back Better approach. First, energy experts were on the ground assessing the situation. Second, the right team was assembled to collaborate to deliver a very quality roadmap in a very short time period. State and investor-owned utilities along with other federal entities and non-profit organizations make up the Puerto Rico Energy Resiliency Working Group, with the initiative coordinated with the assistance of Navigant Consulting.

I spoke with Michael Hervey with Navigant who was immersed in pulling this off. Hervey was serving as the COO with Long Island Power Authority (LIPA) when Superstorm Sandy hit, and is therefore more than competent to assist in the development of this document. Hervey talked through large sections of the plan with me, including the difficulty of reaching transmission in remote areas, the need for more robust design standards and the value gained by locating new transmission along highways.

Let me offer a little recap. You might remember that Hurricane Irma struck Puerto Rico’s northern coastline on Sept. 6, 2017 as a Category 5 storm, knocking out power to more than one million residents and damaging critical infrastructure. Two weeks later, on Sept. 20, Hurricane Maria made its way up the Caribbean as a Category 4 hurricane, bringing winds of 150+ mph and dumping 25 inches (635 mm) of rain, resulting in catastrophic damage of historical proportion. The combined impact of the two hurricanes led to a complete failure of Puerto Rico’s power grid, with little hope of a quick recovery. Because of the extended and unprecedented damage, significant portions of the generation, transmission and distribution systems now must be rebuilt.

The Puerto Rico Energy Resiliency Working Group’s overriding goal is to support the Puerto Rico governor’s office, PREPA, interested stakeholder agencies and the Federal Emergency Management Agency (FEMA) in defining funding requirements and in providing electric power system rebuild recommendations.

The many participants on the Puerto Rico Energy Resiliency Working Group are guided by collective experiences gained responding to and preparing for hurricanes in the areas of power system recovery, system rebuilding and system hardening.

Grid Recommendations

The following measures are proposed to harden and enhance the resiliency of PREPA’s system:

• Reinforce existing direct-embedded poles with enhanced support such as perimeter injected concrete grout or other soil stabilization
• Upgrade damaged poles and structures to a higher wind loading standard
• Strengthen poles with guy wires
• Install underground power lines in select areas prone to high wind damage
• Modernize the T&D system via smart grid investments to make the system less susceptible to extended outages
• Install automated distribution feeder fault sectionalizing switches to enable fault isolation and reduce outage impact
• Deploy modern control systems to enable DER integration and encourage their development
• Adopt effective asset management strategies, such as the targeted inventory of critical spares
• Institute consistent vegetation management practices.
• Apply enhanced design standards for equipment and facilities damaged in the recent storms.

Additional hardening and resiliency actions have been added to this list for consideration. For new transmission, install monopole towers with high-strength insulators. For the distribution system, install concrete and galvanized poles along with building a new backup control center. For substations, use multilayered flood protection for at risk sites. For system operations, install microprocessor-based devices with proven automation and control system technologies.

Now for a deeper dive into the components that make up the delivery system.

The Transmission System

The transmission network consists of 2478 miles (3988 km) of lines that deliver power from generating stations to 334 transmission and sub-transmission substations. Higher voltage lines operate at 230 kV and 115 kV, with lower voltage sub-transmission operating at 38 kV. The backbone of the Puerto Rico transmission system consists of 230-kV overhead lines that form an approximate loop around the perimeter of the island. The 115-kV lines serve all the major load centers on the island. The 38-kV sub-transmission system serves local load centers. The 38-kV system also makes up the primary feeds to the more inaccessible interior regions and most are in difficult-to-reach locations. Many of PREPA’s transmission lines damaged during the storms were constructed decades ago and were located in difficult-to-access areas. PREPA reported that only 15% of the transmission lines are built to a mid-Category 4 criteria and the remaining 85% are built to lesser standards. Consistent with observed wind speeds from Maria, PREPA’s system should be designed and constructed to withstand an upper Category 4 event (155 mph winds) and heavy flood waters.

Transmission Recommendations

To convert the existing infrastructure to a more resilient, robust grid, the working group recommends relocating and upgrading some 350 miles (563 km) of overhead transmission lines while taking into account that design considerations enable grid-scale integration of renewables and accommodate microgrids. Many of the existing sub-transmission lines that run over mountains could be abandoned with new lines placed along existing roadways. Many of the foundations of existing 115-kV poles should be reinforced via concrete grout injection around the base.

It is expected that transmission-hardening recommendations would be funded primarily through FEMA.

The Distribution System

PREPA’s distribution system is made up of roughly 1200 circuits, with more than 30,000 miles (48,280 km) of overhead and underground lines. Most circuits operate at voltages ranging from 4 kV to 13 kV, which is common among electric utilities. PREPA’s distribution system is primarily overhead, with 6% of the circuit miles located underground. Distribution poles are primarily galvanized steel and concrete, with a limited population of wood poles.

Distribution Storm Damage

The distribution system encountered significant damage, with up to 75% of circuits needing repair. Both the overhead and underground systems were affected. The distribution poles were not designed to withstand a Category 4 storm, and underground equipment experienced water and contaminant intrusion. The limited use of deadend breakaways on distribution poles led to a domino effect, with long sections of line failing successively. Concrete and wood poles experienced severe damage, while galvanized steel fared better during the storm. Numerous substations located along distribution circuits that step down primary voltages to lower primary or secondary voltages were severely damaged.

Distribution Recommendations

The working group recommends the rebuild and reinforcement up to 75% of its 1200 distribution circuits. Essential near-term improvements include the following:

• Relocate distribution lines so that they are not on the same side of the street as existing transmission lines to reduce common mode failures
• Upgrade conductor size and use fully insulated wire (tree wire or bundled conductor) in areas where trees are present
• Install breakaway service connectors on poles to limit the number of poles impacted by high winds
• Install automated switching devices, and enhance protection and controls by converting from electromechanical relays and SCADA to more modern and flexible microprocessor controlled devices on critical line segments; at least two automated sectionalizing devices should be installed on overhead mainline sections
• Install underground lines in select areas prone to high wind damage
• Convert lower voltage 4-kV lines to operate at 15 kV, which will improve efficiency and the ability to restore energy demand during storms.

The adoption of advanced control technologies and enhanced operating center functionality will improve visibility and control of distributed resources and support the development of self-healing networks. This includes investing in distribution automation, which includes installing automatic switches, circuit connections, sensors and communications equipment. These investments will improve system reliability, reduce the impact of outages and permit greater penetration of DERs. Key benefits of recommended distribution automation investments include the following:

• Near-real-time visibility for distribution system operators, with telemetry provided throughout the circuits enabling issues to be identified quickly and accurately
• Remote fault isolation and service restoration, thereby decreasing outage duration and area of impact
• Increased operational flexibility with appropriately-sized line sections for circuit switching, which will minimize outages during planned maintenance and unplanned outages
• Enhanced situational awareness for DER operations, including the management and control of smart DER interconnections.

Funding for the distribution recommendations would primarily consist of FEMA funds for hardening the system and other federal or territory funding sources, such as Community Development Block Grants (CDBG) for the deployment of various recommended technologies and system enhancements.

It will likely take five to seven years to complete the recommended control system implementations. Building out the communications infrastructure will likely be closely aligned to the T&D build schedule with the final communications build out taking an additional two to three years.

Renewables Didn’t Go Unscathed

Puerto Rico has approximately 157 MW of installed distributed solar photovoltaic projects spread across 11,000 projects interconnected to the sub-transmission (38 kV) and distribution (13.2 kV and below) systems. The condition of the smaller systems is not well known, but extensive damage occurred on the larger solar and wind farms. The Punta Lima wind farm suffered significant damage, with loss of approximately half the blades and damage to vertical posts. The Santa Isabel wind farm was seemingly intact. Of the five solar facilities, at least one solar farm had extensive damage to a large portion of the panels, which will need replacement.

Appropriate Investment in Energy in Puerto Rico Is Essential

It is critical we get this investment in infrastructure right and the proposed costs are significant. To accomplish all the tasks laid out in the plan, it is projected that $4.9 billion would be required for transmission, $5.3 billion for distribution and $480 million for system operations.

The Puerto Rico Energy Resiliency Working Group has laid out a very actionable and responsible plan that takes into account fast response for urban communities while providing a plan to deliver critical infrastructure to remote, isolated communities. Of course, funding for the rebuild must be worked out going forward, and it is not assured that sufficient can be obtained to carry out all of the objectives laid out by the working group. A large-scale investment in energy can pave the way to provide a more resilient and prosperous future for the 3.4 million citizens of Puerto Rico. ♦

Editor’s note: The complete Build Back Better report is available online.