Temperature-based instanton analysis: Identifying vulnerability in transmission networks

A time-coupled instanton method for characterizing transmission network vulnerability to wind generation fluctuation is presented. To extend prior instanton work to multiple-time-step analysis, line constraints are specified in terms of temperature rather than current. An optimization formulation is developed to express the minimum wind forecast deviation such that at least one line is driven to its thermal limit. Results are shown for an IEEE RTS-96 system with several wind-farms.

I. Introduction

The prevalence of renewables in modern transmission networks has researchers and system operators asking: What happens when the wind changes, and could fluctuations harm the grid? The instanton problem provides an answer, and this paper extends instanton analysis to the temporal setting. Though small deviations from wind forecasts are typically harmless, it is possible for certain wind generation patterns to drive the system to an insecure operating point. Out of all troublesome wind generation patterns, the one that deviates least from the forecast is called the instanton. Instanton analysis uses optimization to find the set of troublesome wind patterns, each of which causes a particular line to encounter its flow limit. By ranking these wind patterns according to distance from forecast, we can characterize the system's vulnerability to forecast inaccuracy and enhance system operator awareness.