The article presents a new method for voltage control in medium voltage distribution networks with dispersed generation. A linear mathematical model of a distribution network has been proposed. The model makes possible to optimally select feeding voltage of a medium-voltage network as well as reactive power in dispersed power sources according to the actual load and active power generation.

The risk of emergencies in power grids may result in the need to repeatedly curtail the power generated from renewable energy sources (RES). The frequency of network emergency states occurring during the year can be determined based on available failure rate statistics. The power redispatch signal (this term means reducing generation in a renewable energy source and correspondingly increasing it in a centrally controlled source) may be issued by the appropriate network operator. The article presents the results of analyses, the aim of which was to assess the probable effects of annual generation reduction in a selected wind and photovoltaic power plant connected at the same grid node. An original method was proposed using Monte Carlo simulation, taking into account the generation technology and its annual distribution, and an external computational "engine" implementing sequences of flow calculations.

In recent years, the rapid increase in installed photovoltaic (PV) capacity in Poland has created significant challenges for low-voltage distribution networks. Excess generation during peak solar hours frequently leads to local overvoltage conditions that exceed regulatory limits, causing PV inverters to disconnect from the grid. This phenomenon reduces the efficiency of distributed renewable energy integration and results in direct financial losses for prosumers. The present study quantifies these losses on an annual basis for a single-family household located in southeastern Poland, where overvoltage incidents occurred 614 times over 78 days in 2024. Real operational data from the residential PV installation were analyzed and complemented with detailed PVsyst simulations to determine the amount of energy curtailed due to inverter disconnections. The analysis revealed that daily energy losses can reach up to 22% of potential production, depending on the duration and frequency of overvoltage events. Furthermore, several technical and organizational measures are proposed to mitigate the issue, including grid reinforcement strategies and demand-side management. The findings highlight the necessity of addressing overvoltage in low-voltage distribution networks to ensure system reliability, enhance renewable energy integration, and maintain the economic viability of residential PV investments.

The article presents the results of analyses of the impact of prosumer photovoltaic sources on selected electrical parameters monitored in the LV network. A model of distributed control of the LV network is presented, taking into account the possibility of voltage regulation in the MVILV substation and in selected network nodes. In this model, particular attention is paid to the correlation between the dynamics of changes in the network and the time constraints contained in the control algorithm and in the communication process. The time criteria for the operation of individual blocks of the distributed control algorithm are presented.