Systematic Analysis of Technical Problems Arising During the Integration of Renewable Energy Sources into the Power Grid

Abstract

This article presents a revised systematic technical analysis of the main problems arising during the integration of renewable energy sources (RES) into electric power grids. The study focuses on variable solar photovoltaic (PV) and wind generation, inverter-based connection, reduction of system inertia, frequency stability, voltage regulation, reactive power balance, harmonic distortion, short-circuit strength and relay protection selectivity. In response to the need for a stronger quantitative basis, the paper combines classical power-system equations with recent literature on grid-forming inverters, synthetic inertia, weak-grid operation and smart inverter functions. The scientific novelty of the study is not the derivation of new equations but the integration of these known indicators into a single operational-control framework that maps the chained interaction between inertia, rate of change of frequency (RoCoF), short-circuit ratio (SCR), voltage control, total harmonic distortion (THD), protection coordination and Battery Energy Storage System (BESS) support. A sample calculation is also introduced to demonstrate how a reduction in equivalent inertia increases RoCoF after a generation outage and how fast frequency response (FFR) can mitigate the effect. The results show that reliable integration of high RES shares requires grid reinforcement, flexible generation, BESS, grid-forming inverters, adaptive protection and updated grid codes.