Page 15 - CARILEC CE Industry Journal_Oct_2019
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found that undergrounding would not be economically
                                                                feasible and would negatively impact customer rates.

                                                                Additionally,  although  undergrounding  lines  can  reduce
                                                                the  frequency of  outages, studies  also  showed  that
                                                                restoration time can increase due to the complexities of
                                                                the systems and the inability to visually identify the
                                                                cause of the fault.  However, while costs are currently
                                                                prohibitive for total system undergrounding, utilities and
                                                                regulators should review the metrics for selective
                                                                undergrounding as a potentially viable solution for
                                                                vulnerable areas and for locations serving critical
                                                                facilities such as police, fire, hospitals, water utilities,
                                                                and telecommunications.  It’s also important to note that
            LEARNING FROM EXPERIENCE                            undergrounding does not totally protect the system from
                                                                storm surges and flood damage.

            In 2004, Hurricane Ivan devastated the nation of    Other hardening  measures for poles  and  lines  can  be
            Grenada. Grenlec, the island’s sole utility, suffered   incorporated as part of routine maintenance schedules
            unprecedented  damage  to  its  distribution  system.   as new designs become available and older equipment
            However, because of good planning and sound design in   is retired and replaced.
            prior years, the generation assets were largely untouched
            by the storm and were made operational within 24    Overall, utilities need to weigh the size of the system,
            hours of the “all-clear” status. Guided by its Disaster   critical loads, relative costs, environmental factors,
            Recovery Plan, Grenlec restored power rapidly to critical   causes of outages, and weather-related risks to provide
            locations for medical, water and public safety services.   the appropriate level of resiliency.
            Full restoration was completed within a year.
                                                                Distributed generation and microgrids. Solar photovoltaic
            Resiliency and redundancy were designed into the    (PV), wind, fuel cells, and fossil fuels, can provide
            restoration plan and processes as Grenlec rebuilt the   additional capacity to enhance resilience during major
            electrical system in Grenada. The flexible nature of the   outages. In some cases, systems can disconnect from the
            generating assets allowed Grenlec to segment the    main power system and serve as backup power.
            system into multiple “islanded” power systems,
            essentially creating ad hoc microgrids. The distribution
            system was then rebuilt radiating from these “hubs.”

            Assistance with this rebuilding effort was afforded by
            several crews  from  neighboring  islands’ utilities. A
            disaster relief program, organized by the Caribbean
            Electric Utility Services Corporation (CARILEC), ensures
            that sister utilities are available to support each other in
            recovery and restoration efforts.  Lastly, and  very
            significantly, Grenlec also maintains a self-insurance
            “Hurricane Fund” which allowed the utility to promptly
            pay for restoration materials and efforts.



            METHODS OF IMPROVING
            RESILIENCY

            Undergrounding transmission and distribution lines is
            one of the most common measures proposed for
            mitigating storm damage. However, in many cases, the
            costs associated with converting overhead systems is
            extremely high. According to a report by Edison Electric
            Institute  for  U.S.  utilities,  Before and  After  the  Storm,
            not one study included in the report recommended a
            complete   conversion  of  overhead   distribution
            infrastructure to underground, given that the estimated
            costs would be in the billions of dollars. The studies


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