SPIDERS: A Model for Utility Microgrids

SPIDERS: A Model for Utility Microgrids

In recent years, the United States has seen an increase in the number of disruptions in electrical service to end-use customers due to severe weather events. With the increasing frequency and severity of these events, outages can be on the order of days and weeks. The design and operation of the electrical infrastructure needs to be re-evaluated to prevent long-term outages from becoming commonplace. One technology that has the potential to mitigate the impacts of severe weather related events is the microgrid.

By increasing the observability and controllability of the local infrastructure, and facilitating the integration of islanded generation, microgrids can supply critical end-use loads when the bulk power system is not available. Japans Sendai microgrid did so in the aftermath of the great earthquake and tsunami of 2011, as did microgrids in the U.S. Northeast United States after Hurricane Sandy.

And yet despite the clear benefits that can be provided by a microgrid during a severe weather event, and despite numerous demonstration and pilot programs, relatively few microgrids are in operation in the United States. The limited penetration of microgrids into the nations electric infrastructure can be attributed to uncertainty, both true and perceived, associated with designing, building and operating the systems.

In an effort to reduce such uncertainties, the U.S. Department of Defense initiated a Joint Capability Test Demonstration (JCTD) project that involved the Department of Energy and Department of Homeland Security to address these issues. SPIDERS (Smart Power Infrastructure Demonstration for Energy Reliability and Security) is a three phase project that is being conducted at Joint Base Pearl Harbor Hawaii, Fort Carson Colorado, and Camp Smith Hawaii; with the evaluation of the third and final phase scheduled for mid-2015. The program aims to develop and demonstrate a cyber-secure microgrid architecture that can be used to supply critical end-use loads when the bulk power system is not available. SPIDERS is strongly focused on transitioning the technologies, concepts and lessons learned to a broad number of stakeholders, both within and external to the Department of Defense, with U.S. Naval Facilities Engineering Command and the Pacific Northwest National Laboratory serving as the designated transition managers.

The basic approach is crawl, walk, run, with a view of streamlining processes for defense and civilian microgrid adoption. Phase 1, the crawl stage, is sited at Joint Base Pearl Harbor Hickam, Hawaii. Phase 2, the walk stage, is located at Fort Carson, Colorado. The run stage, which is the third and final Phase, is at Camp Smith, Hawaii. In each case, an Integrated Assessment Plan (IAP) plan and a utility assessment report will be developed.

Each of the three operational demonstrations is based on an IAP, completed sixty days prior to its execution. Plans are geared to evaluate each systems ability to meet four high-level requirements set out in the SPIDERS implementation directive:

  •     Protect task critical assets from loss of power due to cyber-attack.
  •     Integrate renewables and other distributed energy generation concepts to power task critical assets in times of emergency.
  •     Sustain critical operations during prolonged power outages.
  •     Manage installation electrical power and consumption efficiency, to reduce petroleum demand, carbon boot print and cost.

These goals cannot be evaluated by any single metric. To address this issue, the integrated assessment plan is divided into six Measures of Effectiveness (MOEs): effectiveness efficiency, renewables integration, suitability, cyber security, and cost. From these measures, it can be seen that plans are designed to evaluate not just the electrical performance of the microgrid, but also the operational impacts, cyber performance, human factors issues, and costs. Furthermore, within each of the six measures, there are numerous Measures of Performance (MOPs), which correlate to specific measurements. This provides an evaluation structure that tracks results from individual measurements up to top-level goals.

To the extent possible, the results of the three operational demonstrations will be made publically available in the utility assessment reports. This provides utilities and other microgrid operators with two distinct benefits. First, detailed results from three different microgrid deployments will be provided. The three sets of results show a progressing level of complexity culminating in the complete SPIDERS concept. Second, an evaluation framework is provided that utilities can use to evaluate their own potential microgrid deployments. The Phase 1 operational demonstration was completed in 2013 and Phase 2 in 2014; and Phase 3 is scheduled to be finished in 2015.

The results from the first two demonstrations have shown the effectiveness of a cyber-secure microgrid with significant penetration of renewable resources. In both phases there were reductions in fuel consumption because of the ability of the microgrid to optimize fossil fuel generation assets and to incorporate renewables. System reliability was increased because of the integration of generation resources, which provides resiliency to contingencies. Significant information on how operators and maintenance staff interact with microgrids was also collected, which showed that while microgrids provide significant benefits, it is necessary to properly integrate the new operational strategies. These operational benefits were achieved in a cyber-secure system.

The combination of integrated assessment plans and utility assessment reports has provided utilities and other interested parties with an example model of how to evaluate the performance of microgrids in a systematic manner that can be presented to their regulatory authority. While this may not address all of the uncertainties associated with deploying microgrids, it forms a basis for developing individual plans to minimize uncertainty. The complete assessment documents for Phase 1 and Phase 2 are available from PNNL, as are portions of the Phase 1 and Phase 2 UARs.

Source: Smartgrid IEEE

Smart Grid Bulletin April 2018

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