Integration of Solar PV and Wind Power into Modern Power Grids: A State-of-the-Art Review

Solar photovoltaic (PV) and wind generation now supply a rising share of electricity in many countries, and the systems built around coal, gas, and hydro were not designed for them. Both resources are weather-driven, both connect to the network mostly through power electronics, and both are often located far from load centres. This review examines how these characteristics affect network operation and how the research and industry communities have responded. It covers generation and conversion technologies, the main operational problems (voltage and frequency regulation, falling inertia, power quality, fault behaviour, congestion, and curtailment), and the main remedies: grid-forming converter control, energy storage, hybrid plants, flexible transmission, demand-side flexibility, and data-driven forecasting. The paper adds worked equations, simulated illustrations, and side-by-side comparisons of technologies, control methods, forecasting approaches, and documented system events. Open research problems are identified for networks that must run with very high shares of inverter-based generation. The review is intended as an organized starting point for researchers and engineers working on renewable-rich power systems.