Three-Stage Priority List Unit Commitment for Large-Scale Power Systems Considering Ramp Rate Constraints

This article introduces a new, fast, and efficient priority list (PL) unit commitment (UC) for large-scale power systems considering ramp rate constraints. The proposed three-stage technique decomposes the UC problem into subproblems. These subproblems are PL formation of the generation units, switching power limits of the generation units, unit status calculation, and economic dispatch of the committed units. The first stage of the proposed technique satisfies the initial status constraints of all available units. The second stage achieves the load demand and minimum up/down time constraints. Finally, the third stage satisfies the up/down ramp rate constraints of all committed units. The second and third stages allow PL updating, which guarantees cost minimization. Verification of the proposed technique has been achieved by applying it to the ten-unit test system and its multiples of 20, 40, 60, 80, and 100 units, which are commonly used as test systems of UC problems. The obtained results ensure the efficacy and effectiveness of the proposed technique. The introduced technique has succeeded in achieving optimal solutions without iterative solutions and avoiding local minima. The efficacy, accuracy, and solution speed of the proposed approach are also not significantly affected by the complexity and the size of the power system, which emphasizes the reliability and efficacy of the proposed approach to solve large-scale UC problems.