Long Island Power Authority (LIPA, Long Island, New York, U.S.) was created as a state municipal agency to absorb the debt of the Shoreham Nuclear Power Plant, which is located on Long Island. In 1998, LIPA bought the T&D assets of the Long Island Electric Co. and signed an eight-year outsourcing agreement with a company now called KeySpan Energy (Long Island) to manage these T&D assets. The enabling legislation also involved outsourcing agreements with rights for generation operation and repurchase, and all energy-procurement services.

LIPA's director of T&D faces the many opportunities and challenges of running a 4600 MW, 1.1 million customer-based utility as a total turnkey outsourced model. As the sole individual in LIPA's T&D organization, the director is responsible for the outsourcing agreements that cover operations, maintenance, construction, service restoration and T&D budgets. He also is responsible for balancing the outsourcer's goal to maximize profits and LIPA's goal to reduce rates.

Working together, LIPA's T&D director and KeySpan Energy's outsourcing manager have been able to improve reliability while striving to control costs and to maintain the 20% rate reduction that was the result of the creation of LIPA in 1998.

With a geographical location off the coast of the states of New York and Connecticut, Long Island occasionally is referred to as the first line of defense for any northeasters, hurricanes and other major weather patterns that come barreling up the East Coast off the Atlantic Ocean. Effectively, LIPA takes the brunt, slowing the impact of weather patterns before they hit the mainland, a job other utilities in New York and Connecticut appreciate.

With the high concentration of vegetation, and the compact design and construction of overhead lines in a dense residential setting, vegetation is the leading contributor of storm outages even with the extensive use of covered wire.

When LIPA took over the T&D assets, it engaged Navigant Consulting Inc. (NCI, Chicago, Illinois, U.S.) to assist in managing the outsourcing contract with KeySpan Energy.

The electric-utility environment is changing considerably, in particular there is an increased emphasis on performance, resource constraints, and aging infrastructure as well as increased pressure to identify and manage system risk. As the owner of the assets with specific agreements that place the majority of the risk and incremental costs of storms as its responsibility, LIPA needed a method that supplemented the current planning techniques with a probabilistic approach, coupled with a program tailored toward minimizing vegetation-related storm damage — the largest contributor of storm outages.

While LIPA's current planning and maintenance process was consistent with the rest of the industry, its risk was more pronounced using the status quo, operating as a total outsourced utility.

LIPA recently ranked in the top quartile in non-storm reliability indices, as defined by the New York Public Service Commission, due in no small part to the efforts during the past several years on several new initiatives. These initiatives include:

  • Implementing a 3-5-7 year optimized trim cycle. Based on the lessons learned from getting all circuits under a five-year trim cycle in 1999, LIPA launched the 3-5-7 year optimized trim program in 2000. This program tailored the individual circuit's performance, determining the optimal trim cycle based on existing vegetation, expected growth rates and prior success in trimming efforts.

  • Installing more than 61% of the radial overhead circuits with at least one midpoint and one tie auto switching point, all via supervisory control and data acquisition (SCADA). This has dramatically decreased the amount of customers impacted during an outage, assisted in pinpointing the location of the outage and reduced the number of customers impacted during the fault with the ability to quickly back feed and restore customers.

  • Instituting a circuit-improvement program in 1994 to target the removal of armless construction, installing additional lightning arrestors and 4-ft (1.2-m) crossarms in hazardous tree locations on the three-phase mainline.

While these initiatives have delivered significant success in minimizing the impact of non-storm outages, they had only a marginal effect on reducing the magnitude of vegetation-related damage during storm events with sustained winds in excess of 50 mph or during heavy icing conditions.

LIPA and KeySpan have done a great job of enhancing the reliability of the system during non-storm operating conditions, which has had some impact on storm performance, but LIPA realized early on it had significant storm-damage exposure, which its traditional engineering planning tools did not reflect.

What LIPA needed was to supplement these existing tools with a probabilistic model that reflected the different parameters that occur during storm events. While the system may be adequately designed for normal day-to-day operation, during a storm event the system could be radically reconfigured such that backups may not be available, equipment called upon to operate may not, and system capacity and equipment may already be too heavily loaded to provide backup capability.

For this reason LIPA and KeySpan launched a pilot program in 2001 to incorporate two new approaches, introducing a probabilistic model to supplement LIPA's existing process along with an enhanced vegetation program intended to minimize storm damage.

For the probabilistic model, the analysis considers the following:

  • Vegetation density and species

  • Whether the outages were predominately three phase or single phase

  • System configuration (ability for switching and backup)

  • Historical crew response and restoration

  • Historical storm feeder performance

  • Weather events and characteristics (ice, lightning, wind direction)

  • Overhead construction and non-storm performance

  • Detailed field observations.

The output of this analysis determines the relative probability of a feeder's susceptibility to storm damage. These feeders are screened using a cost-per-customer avoided calculation that compares various alternatives such as installing additional isolation devices, reinforcing infrastructure (pole replacements, reconductoring), or pursuing enhanced vegetation trimming and removal.

The enhanced vegetation program, which is in addition to the existing program, is funded primarily from savings achieved through the 3-5-7 year optimized trim cycle. This enhanced program focuses on working with the system arborists to identify and remove the growth most likely to structurally fail during a future storm under the same characteristics that have historically impacted that feeder. Depending on the location and field construction, the key drivers in determining the proper trim and removal technique may be ice loading, wind shear direction, vegetation density and species, soil erosion or a combination. This is different from the technique used in cyclical clearance-based trim or a ground-to-sky approach.

By strategically focusing the efforts on feeders identified with the probabilistic model, LIPA found that pursuing enhanced vegetation trimming and removal is typically the most cost-effective solution.

The analysis confirmed that enhanced vegetation remediation with a focus on minimizing three-phase outages was the right combination. Therefore, targeting vegetation on three-phase mainlines had the greatest impact on minimizing the cost, damage and customer interruptions during a future major storm event.

With the completion of the analysis in late 2001, LIPA and KeySpan have identified several feeders and have begun to bid out the work for enhanced trimming and removal. LIPA continues to strategically apply the techniques of the enhanced vegetation program and to further roll out the probabilistic planning model to supplement present techniques toward system planning and design.

This will be a win-win situation for not only the outsourcer but also for LIPA as it strives to identify and minimize the risks impacting and influencing rates.

Mike Hervey is the director of Transmission and Distribution for the Long Island Power Authority (LIPA). He has nearly 22 years of experience that includes nearly every aspect of T&D. He joined LIPA in 2000 where he is systematically applying a combination of engineering and business processes to T&D asset decisions.

Thomas Spatz is the director of Electric Service for KeySpan Energy. He has 28 years of experience in the electric-utility business and has held director positions in both the operating and engineering areas of KeySpan. He has earned the BSEE, MSEE and MBA degrees.

Charles A. Fijnvandraat is a senior engagement manager at Navigant Consulting (NCI). He has more than 15 years experience in the electric-utility industry having worked both as a utility manager and as a consultant assisting clients in improving reliability, design optimization, increasing operating efficiencies and maximizing IT/GIS investments. Fijnvandraat also is a member of the IEEE and is a registered professional engineer.