# Optimal Management of High-Voltage Line Congestions Using Power Source Redispatching
## 2 Literature Review  
An increasingly common problem is the need to limit the power of RESs. These limitations are caused by various factor-balance issues related to too-high solar generation, too-high wind generation, or line overloads. Other factors that determine the occurrence of network problems are changes in the network structure related to operational switching, the occurrence of emergency states, or even the construction of new lines or the installation of new transformers [3]. Precise data on energy curtailment in Poland are presented in the paper [4]. In Europe, apart from Poland, wind energy limitations are increasingly common in Ireland [5] and Germany [6]. In the world, however, problems with the integration of all wind sources with the system and, if necessary, the need to limit them occur in China [7] and the United States [8]. The issue of limiting the power of sources has recently gained great importance in Poland due to the overloading of high-voltage lines caused by the connection of an increasing number of RESs [9]. In 2023 alone, 7448 refusals to connect facilities to the grid with a planned capacity of over 83 GW were issued in Poland, which constituted 99.3% of applications for the connection of renewable energy sources [10,11]. The need to periodically limit power in RESs also occurs in other countries, e.g., in Great Britain or Germany, which are the leaders in Europe in terms of total installed power in RESs [12,13]. This is due to the fact that, in a given area, a common problem is too many power plants with a relatively high total capacity, which contributes to the occurrence of current overloads [14, 15, 16]. For this reason, both in the literature and in everyday use by operators, one can increasingly encounter attempts to solve this problem by using methods based on so-called congestion management [17, 18, 19, 20, 21, 22], redispatching [23, 24, 25, 26, 27, 28, 29, 30, 31, 32], or curtailment power in RESs [33, 34, 35], as well as methods based on artificial intelligence and optimization methods [36, 37, 38, 39, 40, 41, 42] or the reconfiguration of the network operation [43, 44, 45, 46, 47]. Redispatching is a change in the previously established generation size as a result of reduced demand for electricity. The use of the redispatching method is possible thanks to the regulation of the European Parliament and the Council of the European Union of 2019 [1]. The issue of examining the impact of connected RESs on the occurring overloads in high-voltage lines was addressed in article [48]. For this purpose, the authors used the power flow tracking method and the DC method. In study [49], the authors used a method based on the optimal selection of sources in which the power was limited. The authors' methodology allowedthem to avoid a situation in which the power was limited in a source that did not directly affect the overloaded line. [PERSON] [25]. also took up a similar direction of their research. He and his team also proposed a methodology based on the optimal selection of limited sources, and they checked the accuracy of their research on the IEEE 118 test network. The authors of [23] used the technique of minimizing overloads using historical data. They conducted their research on a power system with a high saturation of renewable sources, and the obtained results prove that the proposed methodology can significantly contribute to reducing current overloads in transmission lines. As mentioned earlier, optimization methods are increasingly used to balance the power system. For example, in [40], the [PERSON] and [PERSON] team proposed the use of the Genetic Algorithm (GA) to support operators in optimizing the limitation of wind sources with the optimal consideration of regulatory aspects occurring in given countries, as well as the economic aspects. Also in study [50], by [PERSON] and his team, the focus was on the optimal limitation of wind generation using the metaheuristic method of Particle Swarm Optimization (PSO).