Evaluating grid development strategies for a regional grid using dynamic line rating sensors

Traditionally, regional high voltage distribution grid planning relies on conservative line ratings and present value calculations to evaluate alternative grid development plans, as well as strict adherence to the N−1 criterion. However, it is now becoming possible to use dynamic line rating (DLR) sensors to operate the grid closer to its real capacity, as well as adapting probabilistic risk criteria. This work proposes a grid development methodology which compares conservative seasonal line ratings (SLR) to sensor-based DLR of regional grid overhead lines: First, the risk of insufficient reserves in the grid over the long-term planning horizon is quantified using time series power flow and contingency analyses with either SLR or DLR. Then, a risk acceptance threshold is used as a planning criterion to determine when grid investments should be made given a load development scenario. Finally, the strategies are evaluated by quantifying both the risks and the real option of using DLR as a measure to postpone investment decisions. The proposed methodology is demonstrated in a case study of a real regional distribution grid (132 kV) in Norway. The results demonstrate that in order to realize the option value of using DLR in grid planning, the grid company needs to reduce the risk margins used in the operation of the grid.