Risk evaluation of transmission system operation modes and its application at British Columbia Transmission Corporation

Risk evaluation has been applied in transmission system development planning for years. However, it has not been sufficiently addressed in selecting transmission operation modes. A basic fact is that the risk evaluation for system development planning focuses on long-term system reinforcements but does not simulate operational measures in a short period. Selecting the most reliable transmission operation mode under different conditions requires simulation of operation measures such as load transfers, generation pattern changes, switching actions and temporary network reconfigurations. The paper presents basic concepts and modelling considerations to simulate operation measures. It also addresses two other issues that have to be considered in operation risk evaluation: inclusion of dynamic ratings of circuits and a simulation capability over any time length. Selection of the lowest risk operation mode in the BCTC metro system was used as an example to illustrate the concepts and method presented.