TPL-004-0a: System Performance Following Extreme BES Events

System simulations and associated assessments are needed periodically to ensure that  reliable systems are developed that meet specified performance requirements, with sufficient lead time and continue to be modified or upgraded as necessary to meet present and future System needs.


Effective Date
April 1, 2005

R1. The Planning Authority and Transmission Planner shall each demonstrate through a valid assessment that its portion of the interconnected transmission system is evaluated for the risks and consequences of a number of each of the extreme contingencies that are listed under Category D of Table I. To be valid, the Planning Authority’s and Transmission Planner’s assessment shall:

R1.1. Be made annually.

R1.2. Be conducted for near-term (years one through five).

R1.3. Be supported by a current or past study and/or system simulation testing that  addresses each of the following categories, showing system performance following Category D contingencies of Table I.  The specific elements selected (from within each of the following categories) for inclusion in these studies and simulations shall be acceptable to the associated Regional Reliability Organization(s).

R1.3.1. Be performed and evaluated only for those Category D contingencies that would produce the more severe system results or impacts.  The rationale for the contingencies selected for evaluation shall be available as supporting information.  An explanation of why the remaining simulations would produce less severe system results shall be available as supporting information.

R1.3.2. Cover critical system conditions and study years as deemed appropriate by the  responsible entity.

R1.3.3. Be conducted annually unless changes to system conditions do not warrant  such analyses.

R1.3.4. Have all projected firm transfers modeled.

R1.3.5. Include existing and planned facilities.

R1.3.6. Include Reactive Power resources to ensure that adequate reactive resources  are available to meet system performance.

R1.3.7. Include the effects of existing and planned protection systems, including any  backup or redundant systems.

R1.3.8. Include the effects of existing and planned control devices.

R1.3.9. Include the planned (including maintenance) outage of any bulk electric equipment (including protection systems or their components) at those demand levels for which planned (including maintenance) outages are performed.

R1.4. Consider all contingencies applicable to Category D.

R2. The Planning Authority and Transmission Planner shall each document the results of its  reliability assessments and shall annually provide the results to its entities’ respective NERC Regional Reliability Organization(s), as required by the Regional Reliability Organization.

M1. The Planning Authority and Transmission Planner shall have a valid assessment for its system  responses as specified in Reliability Standard TPL-004-0_R1.

M2. The Planning Authority and Transmission Planner shall provide evidence to its Compliance  Monitor that it reported documentation of results of its reliability assessments per Reliability Standard TPL-004-0_R1.


Table 1

TPL-004-0a - Transmission System Standards


TPL-004-0a - Appendix1

TPL-004-0a - Appendix1cont1

TPL-004-0a - Appendix1cont2

TPL-004-0a - Appendix1cont3