Zonal reserve evaluation and optimization method in electricity spot market for power system integrated with wind generation

Most of the existing market clearing schemes do not consider the impacts of the uncertainty of the renewable energy on reserve deliverability and the zonal available reserve. The reserve plan may exist some security risk. A zonal reserve evaluation and optimization method in the electricity spot market environment is proposed in this paper for power system integrated with wind generations. First, the sensitivity of the tie line power with respect to node injected power was calculated with DC load flow. A scenario-selecting method based on the tie line power sensitivities is developed to find out the worst scenario in which the tie line has the highest loadability. For a pre-dispatching plan, the zonal available reserves can be calculated under the worst scenarios and the reserve adequacy is evaluated. Then, for the power system whose zonal reserves are insufficient, the reserve allocation should be optimized according to the present operation state. The reserve optimization model was established taking the total expenses for purchasing reserves as the objective function. The constraints of zonal reserve requirement, minimum local reserve, the tie line transmission power limit and etc. are considered. It is solved iteratively until a solution is got. The solution is the optimal reserve allocation theme. Finally, the proposed method is applied in a 3-region test system to validate its effectiveness. Simulation results show that this method can evaluate the zonal reserve adequacy in the worst scenario and the optimized reserve plan has good feasibility and security.