**Parameters** Δ*P* Power deviation in each scenario *B* Imaginary part in admittance matrix *C* Cost *G* Real part in admittance matrix *N* Number of unit resources *p* Penalty for external supplier's flexibility *y* Series admittance of line that connects two buses *ysh* Shunt admittance of line that connects two buses **Variables** θ Voltage angle *P* Active power *Q* Reactive power *r* Reactive power flexibility used in the operating stage *rlx* Reactive power relaxation in the operating stage *R* Reactive power flexibility contracted at day-ahead stage *RLX* Reactive power relaxation at day-ahead stage *S* Apparent power *V* Voltage magnitude *V* Voltage in polar form *Vsb* Voltage at slack bus Δ*V* Voltage level activated by the DSO in the transformer *X* Binary variable *Z* Auxiliary variable for absolute function linearization **Subscripts** ω Index of scenarios *cb* Index of capacitor bank units *CB* Capacitor bank abbreviation *g* Index of generators units *i*, *j* Bus index *l* Index of load consumers *L* Load consumers abbreviation *lv* Index of levels (tap changing) for capacitor banks and transformers *TSO* Transmission system operator *t* Time index *tr f* Index of transformer units *TRF* Transformer abbreviation **Superscripts** *act* Activation cost of resources in real-time stage *cut* Generation curtailment *Max* Maximum limit *Min* Minimum limit *op* Operating point of the power resource *Q*, *DW* Downward reactive power flexibility *Q*, *UP* Upward reactive power flexibility
