The ATC transmission system consists of assets contributed by entities within the five control areas of the Wisconsin Upper Michigan System. Each of the original asset owners planned their system to separate planning criteria, particularly in regard to transient and dynamic performance. Therefore, as ATC has implemented its own planning criteria, portions of the system may require upgrade to meet the more stringent ATC criteria.

This section of the ATC planning criteria describes the philosophy that will be followed for completing projects in a portion of the system identified as deficient with respect to the ATC criteria.

1) Area does not meet NERC Planning Standards with respect to stability.

• Complete projects required for bringing the existing system into compliance with NERC standards with no intentional delay.
• New generator interconnections are not permitted until the NERC standards are met with the addition of the generator, if the new generator interconnection aggravates the stability condition. [A new generation interconnection is deemed to aggravate the stability performance of an area if a change in scope is required to meet NERC Planning Standards.]
• Depending on the level of risk associated with the deficiency, special operating procedures (restrictions or guides) may be required to mitigate the risk until the system is in compliance. If a new generator interconnection is permitted but still negatively influences the stability condition, the operating restriction may follow a “last interconnected, first restricted” approach.

2) Area meets NERC Planning Standards but not ATC criteria with respect to stability.

• Normal schedule for projects required for bringing the existing system into compliance with ATC criteria.
• New generator interconnections are permitted as long as the system continues to meet the NERC Planning Standards. If the new generator interconnection causes a violation of NERC standards, 1.b above applies.
• Operating procedures will not be required in the interim period until the projects to meet ATC criteria are completed.

3) Area meets ATC planning criteria for existing system but a new generator interconnection causes a violation of:

• ATC planning criteria – New generator interconnection is not permitted until ATC criteria is met with the addition of the new generator.
• NERC Planning Standards – New generator interconnection is not permitted until both NERC standards and ATC criteria are met.