### Main Contributions  
Various approaches based on the classical or meta-heuristic methods have been developed in the literature to solve the OPF problem in the electric networks integrating renewable sources. Most of them have not been tested on the real electric networks but in IEEE or adapted networks imposing certain buses in which renewable sources are located and only for an hourly steady-state. However, a coordinated control methodology that manages the OLTC of the transformers, integrated into the OPF module from the SCADA master system from the Central Dispatch of the DNOs or TSOs, has not been clearly defined in the literature. Thus, the authors proposed the integration framework of an original real-time coordinated control methodology of the OLTCs in a SCADA master system to ensure an optimal voltage level in the electric networks with positive consequences on reducing the power losses. Compared with the previous approaches, the methodology represents a practical application that ensures the flexibility of the voltage control in the electric networks with and without integrated renewable sources, such as wind farms, by the correlation between the tap positions of the transformers. The main contributions refer to the following: \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Reference Year** & \multicolumn{2}{c}{**The Treated Topic**} & **Contribution** & **Optimization Method** \\ \hline \multirow{4}{*}{[28]} & \multirow{4}{*}{2017} & Impact on renewable energy & \multirow{4}{*}{The guidelines for a decision-making process leading to rapid implementation various scenarios} \\  & & sources integrated into the & & \\  & & Romanian power system on the electrical network operation considering the reduction of & & \\  & & electricity consumption & & \\ \hline \multirow{2}{*}{[29]} & \multirow{2}{*}{2015} & Optimal power flow in the presence of wind power & The optimal power flow with the wind power sources integrated & \multirow{2}{*}{Cuckoo search—meta-heuristic optimization} \\ \hline \multirow{4}{*}{[30]} & \multirow{4}{*}{2018} & Impact of incorporating wind power generation on the power system on presence of voltage source converter & The optimal power flow incorporating wind power generation on the presence of VSC-HVDC & Ant Lion optimizer—meta-heuristic optimization \\ \hline \multirow{4}{*}{[31]} & \multirow{4}{*}{2021} & Optimal operation of the power systems, including the solar sources & The optimal power flow, including minimization of the fuel cost and improving the dynamic performance & Gradient descent algorithm—classic optimization \\ \hline \multirow{4}{*}{[32]} & \multirow{4}{*}{2016} & Optimal operation of the large electric networks with distributed energy resources & The optimal power flow from the radial electric networks integrating distributed energy resources & Gradient algorithm—classic optimization \\ \hline \multirow{4}{*}{[33]} & \multirow{4}{*}{2008} & \multirow{4}{*}{Optimal operation of the power systems} & A new strategy based on reduced gradient method with techniques from augmented Lagrangian and log-barrier to solve the optimal power flow & Reduced gradient method combined with the augmented Lagrangian method with barriers—classic optimization \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Cont. * Developing a data structure integrated into a real-time query procedure that uploads information from the SCADA master system and saves them in two databases (Topology Database and Profiles Database) accessed by the OPF module. This structure enables high-speed data processing. * Treating the OPF problem as a successive quadratic programming (SQP) problem and accelerating convergence using the conjugate reduced gradient method. The small number of iterations and the fast computational time represent the strong points and recommend it for real-time work.