Overview of Transmissions:

The purpose of transmission elements is to see to it that the transmission system is operated in such a way that instability, cascading outages or uncontrolled separation does not take place. These are likely to occur due to a very severe contingency or specified multiple contingencies.  If the transmission enters into an operating stage for which the determined operating limits are not valid, the case is considered to be an emergency and the operations shall be restored in order to respect the proven power system limits in a time span of thirty minutes.

The elements of a transmission operator shall make all possible efforts to remain connected to the interconnection between them. If the transmission operator determines that remaining interconnected leads to an unavoidable danger of violation of any IROL or SOL, then it make actions that it deems necessary so as to protect the area within its charge. The transmission operators, singly or jointly with other transmission operators, will maintain, develop and implement the formal policies and the procedures to provide for reliability of transmission. The formal policies and procedures shall meet the needs of execution and coordinating activities that are likely to impact the inter-regional and intra-regional reliability, such as monitoring and control of voltage levels, real and reactive power flows; switching of transmission elements, planning outages of transmission elements and responding to violations of the IROL and SOL.

The transmission operator that enters into an unknown operating state will have to provide upon request evidence which could include operator logs, transcripts of voice recording, voice recordings, electronic communications, alarm programs, or any other evidence that will be used to restore operations so that they can restore operations to protect proven reliable limits of power systems within 30 minutes.

Questions:

• What happens when the transmission enters into an operating stage for which the determined operating limits are not valid?
• What purpose do the formal policies and procedures serve?