# Optimal Management of High-Voltage Line Congestions Using Power Source Redispatching
## 3 Description of the Research Methodology  
The considered research problem concerns the elimination of power line overloads by means of an optimal change in the power distribution in RESs (minimal power reduction in RESs) while maintaining the power balance in the network. The assumption is that, at the current value of power generated in the considered RESs (which is assumed as the maximum possible generation at a given moment of time), such an optimal power distribution in these sources is sought that will ensure the elimination of the resulting overloads of power lines. This means that the obtained power values in RESs (as a result of solving the optimization problem) will always be lower than their current generation capabilities. The necessary reduction of power in RESs will be at the same time minimal in a given operating state, and thus, the total power in RESs will be maximal from the point of view of eliminating line overloads and maintaining the power balance in the power system. The maximum generation at a given moment of time is expected by investors. This is also beneficial from the point of view of network operators, who will use power redispatching to a lesser extent and, thus, incur lower costs of this action. Therefore, those RESs that contribute to congestion to the least extent will be rewarded. During the optimization process, their generation will be minimally reduced. A greater power reduction will occur in those RESs that contribute to the occurrence of congestion to a greater extent. It should also be noted that each change in generation resulting from changes in atmospheric conditions (sunlight in the case of photovoltaic farms and wind speed in the case of wind farms) will involve resolving the optimization task and searching for the optimal vector of power generated in the RESs under the given conditions. The general algorithm of the proposed calculation methodology is presented in Figure 1.  
The optimal change of power generated in both the RESs and the sources responsible for maintaining the power balance is referred to as power redispatching. This is a periodic action, used after other possibilities have been exhausted, because it involves the need for financial compensation for investors. The possibility of redispatching the power of sources is enabled by the EU regulation [1], which appeared in 2019. Previous methods of limiting power in RESs consisted either of switching off sources indicated by network operators or of proportionally limiting their generated power. These were not optimal actions. This is a research gap in the literature. Works devoted to this topic focused mainly on optimizing the operation of RES sources without the prior selection of those that are most responsible for line congestion. This article proposes an original methodology aimed at minimizing power reduction in RESs. This means maximizing the total power generated in the analyzed RESs. Generally speaking, the main assumption is to eliminate line congestion with minimal generation limitation in the indicated sources. Generally speaking, the calculations are carried out in two stages. After reading the test network model and indicating the sources responsible for maintaining the power balance, in the first step, the sources responsible for the occurring line overloads are selected. The method of tracking active power flows is used for this purpose.