Transmission Security Probabilistic Techniques Hybrid Integration of Probabilistic Methods into the Creation of Deterministic Base Cases For Transmission Planning

Over the past five years, ISO New England has been exploring methodologies to better reflect the reasonable likelihoods of transmission planning-related uncertainties in a manner consistent with operations-related risks. The work was, in large part, motivated by stakeholder requests to develop consistent methodologies of defining “reasonable stress” in reference to the creation of base case dispatches for transmission planning studies. The key challenge is to determine the reasonable conditions for which the system should be planned so that it will remain reliable and operable over the planning horizon mandated by standards and in a manner to avoid overbuilding the transmission system at a significant cost to ratepayers. This paper will explore the considerations leading up to the recent hybrid integration of probabilistic methods into deterministic transmission planning and detail some of the challenges experienced during the process as well as areas of research needed going forward.