Kansas City, Mo., April 11, 2011 — Burns & McDonnell has been engaged by Duke Energy to perform a comprehensive system survey and analysis of 12,065 circuit miles of transmission lines greater than 100 kV.
The survey and analysis will enable Duke to comply with the Facility Ratings Methodology Level 2 Alert issued by the North American Electric Reliability Corporation (NERC) on October 7, 2010.
The Burns & McDonnell survey and analysis will determine how Duke’s transmission facility ratings are affected by actual field operating conditions.
Under its contract with Duke Energy, Burns & McDonnell will obtain aerial surveys of all transmission facilities and utilize the data to develop computerized models of each line with an accurate representation of survey conditions.
The models will be used to perform a thermal rating assessment for each line at both NERC and Duke clearance requirements and to develop a summary of results showing any areas of non-compliance.
A NERC investigation of a recent outage revealed widespread discrepancies between the allowable operating temperatures of conductors related to line clearances and actual line clearances in the field.
The discrepancies compelled NERC to issue the Level 2 Alert, which requires transmission facility owners, operators and planners to identify any potential discrepancies between design and actual field conditions of transmission equipment and facilities over 100 kV.
NERC intends to review each transmission system owner’s facility ratings methods and tolerances to verify line clearances and assess the full extent of discrepancies that could impact overall system reliability.
The assessments and reporting requirements are on an aggressive schedule with any high priority discrepancies due to NERC by year-end 2011. Medium-priority discrepancies are required to be reported by year-end 2012 and low-priority discrepancies are due by year-end 2013.
Field remediation of any discrepancies are to be completed within one year of the date reported to NERC unless an extension is allowed by the regional transmission organization or independent system operator.
NERC’s goal is to systematically identify the scope of the potential problem, prioritize corrective action to best maintain reliable system operation, and raise overall industry understanding and awareness of the need for continuous knowledge of accurate field conditions, including such factors as vegetation, encroachments, design deviations and other issues relating to conductor clearances and, ultimately, maximum operating temperatures and line ratings.