Wind Energy Curtailment for Optimal Operation of Power Systems Under Uncertainty

Abstract

As the penetration of wind power increases in power systems, there is a need to address the effect of wind forecasting error during the real time operation. The role of the Transmission System Operator (TSO) in electricity markets is to ensure safety and reliability of the power system. Currently, most power systems clear the spot market based on supply and demand bidding curves. Under the context of unit commitment, the objective of the TSO is to minimize the generation cost. Such an approach is usually deterministic and does not account for the uncertainties in the system. The aim of this thesis is to formulate a mathematical model that optimizes power system operation. This is achieved by taking into account the expected cost of wind power forecasting error with wind energy curtailment. An additional aim is to compare the operational cost of the proposed optimal system operation and the current system operation in the Nordic power system. The economic value of wind energy curtailment is also evaluated. It is observed that day ahead scheduling considering the expected cost of net demand forecasting error will reduce the total cost significantly. In other words, when the wind uncertainty increases the ability to down regulate or the ability to curtail wind generation reduces the total cost of system operation. A 36 unit system with a lost load value of 6000$/MWh is considered for different variations of standard deviation of net demand forecasting error. At 5% of standard deviation (SD) of net demand forecasting error, the total cost of system as per the current system operation is 456221$ while the case considering net demand forecasting error is 39859.4$. At SD of 20%, for the case considering net demand forecasting error the total cost of current system operation is 1585510$ while the case considering net demand forecasting error is 41380.6$. For SD values greater than 20% the case with net demand forecasting error does not decreases the total cost. For SD values higher than 20%, a method is proposed which allows wind curtailment to have optimal system operation. At 55% of SD, the total cost of the system operation with the proposed method is almost reduced by almost 63 times compared to the cost of current system operation case.