The energy transition is significantly changing the world s energy mixes. In Brazil, hydroelectric power has occupied more than half of the total installed energy capacity for almost fifty years, however its energy mix is also being transformed by the variable renewable energy. The increase of wind and solar photovoltaic power plants in the system is a concern for systems operators worldwide. Wind and solar energy do not produce greenhouse gases but they have characteristics that make the system planning and operation more complex and dynamic. In an electrical grid with high intermittency and variability generation, the system needs more flexibility to safely deliver power to consumers. In the absence of sufficient flexibility, the operator has as last step the power curtailment. In many countries, this resource is being widely used due to the rapid deployment of wind and photovoltaic power plants in recent years. These restrictions can generate additional costs for the generator or the consumer and may pose a challenge to achieving renewable energy global targets. Hence, substantial renewable curtailment are undesirable and require additional measures to improve their predictability and equity. This work proposes a methodology to optimize the variable curtailment of renewable energy together with the allocation of system reserves, considering the intrinsic uncertainty of these sources. This work aims to support the operator in his decision-making in daily scheduling by bringing it closer to real-time operation, as well as to improve reserve requirements and define a transparent criterion for distributing renewable generation curtailment.