NERC Alert: What to do about those “Points-of-Interest” found?
By Ron Stelmak, The Valley Group; and Ricardo Urdaneta, GeoDigital Business Development
Can technology help reduce both the time to complete and the overall remediation costs of the mitigation phase of the NERC Alert, while avoiding the need to lower line ratings in the process?
In the vast majority of cases the answer is YES!
GeoDigital is the leading supplier of airborne asset mapping & LiDAR technology to the energy industry in North America; and as part of our corporate mission we are continuously looking to ways to improve the value of actionable imagery. With our capabilities and technology, we can not only support utilities in determining if discrepancies exist between the design and actual field conditions of your transmission facilities but we can assist in helping you and your engineering partners to rapidly remediate any issues found. As your partner in keeping the power grid safe, reliable, and delivering its full capacity, we are today offering you options that may allow you to mitigate, at low cost, discrepancies that would otherwise result in the derating of the facility or expensive construction projects.
A proven technology, Dynamic Line Rating, is already available and in use at many utilities throughout North America that can resolve most NERC Facilities Rating Alert issues very quickly and at a fraction of the cost of alternatives. Application of this technology frees up essential resources for daily operations and previously planned expansions.Transmission lines are designed to operate at a maximum conductor temperature that will not harm the conductor and will not cause the conductor to sag below its safe clearance to ground. That maximum permitted operating temperature is represented as the “Safe Design Isotherm” curve in Figure 1
The MVA that can be carried by the conductor without exceeding the safe design isotherm (temperature) varies with weather conditions. The conductor’s temperature is a thermodynamic balance of the heat added by both electrical losses and solar radiation minus the heat removed by both wind and the ambient air temperature. Cool, cloudy, and windy conditions efficiently dissipate the heat of higher MVA loads, while hot, sunny, and calm conditions result in inefficient heat dissipation and therefore MVA loads must be reduced.
When real time monitoring is not available, engineers have no knowledge of weather conditions and must exercise good judgment by assuming the worst possible combination of no wind, full sun, and high ambient temperature. Under those assumptions, an engineer will set the static (fixed) rating in our example at 75 MVA to be certain that the conductor will never be overheated under any conceivable load and weather conditions. Since those worst weather conditions rarely occur, a perfectly good transmission conductor is left significantly underutilized nearly all of the time.
Dynamic Line Rating (DLR) methods safely capture the underutilized design capacity of the transmission line. Instruments installed on the conductor track the “Safe Design Isotherm” through changing weather conditions. The instruments determine exactly how many MVA may be carried by the conductor without exceeding the permitted maximum operating temperature. For example, on any given day conditions may be such that the conductor can safely carry 125 MVA versus the fixed static rating of 75 MVA.Dynamic Line Rating Systems make it possible to avoid lowering the static rating by tapping into the line’s true capacity while still maintaining present operating practices and a complete level of public safety.
Figure 2 shows what happens when a static rating is reduced (derated) as a result of a Lidar survey that indicates that the safe design isotherm must be reduced to a lower temperature. Note that nearly all of the capacity associated with the previous static rating is recaptured with DLR. In most cases, the line can be operated at the previous static rating 99+% of the time including first contingency events. For the fraction of a percent of time when the line will not survive a future contingency event, system operators are given advance warning and appropriate actions can be taken pre-contingency. Note that using DLR to enable the higher static rating means the line is always operated within the limits prescribed by NERC’s FAC-008.
What are the down sides? None. What are the upsides? In some cases, it may be possible to raise the static limit rather than lower it.
In 60 minutes, we can demonstrate to you and your team exactly how this DOE and NERC recognized smart grid technology will allow you to efficiently meet the reliability goals of the NERC Facilities Ratings Alert. Specifically, we would like to share with you how to:
• Retain system capacity – keep present ratings on most lines
• Reduce NERC Alert remediation costs by up to 95%
• Mitigate NERC violations in a few weeks versus many months or years
• Improve system reliability and integrity
• Upgrade asset utilization and grid intelligence
• Achieve all of the above while remaining fully NERC compliant
GeoDigital takes the NERC Facilities Rating Alert off your desk, and leaves you free to focus on the business of delivering power
Please call Ricardo Urdaneta at (703) 264-1331, and we will answer all of your questions.