Variable Resource Dispatch Through Do-Not-Exceed Limit

Due to the variability of renewable resources, the ISO tries to identify do-not-exceed (DNE) limits, which are the maximum renewable generation ranges that the power system can accommodate without sacrificing system reliability. The problem is formulated as an optimization problem whose objective is to find the largest operating ranges of variable resources such that the system remains feasible under any generation realizations within the range. Computing the DNE limits can be conceptually translated into finding the largest uncertain set of a robust optimization problem. Depending on the assumptions on how the system responds to the uncertainty of renewable resources, three alternative approaches are developed to convert the nonstandard robust optimization problem into linear programming, bilinear programming and two-stage robust optimization problems, respectively. Although the linear programming problem is easier to solve as compared to the other two alternatives, its resulting DNE limits are the most conservative. Therefore, the trade-off needs to be considered when deciding which approach is the most appropriate in real-time operation. A 5-bus system and the ISO New England power system are used to test the proposed approaches.