This paper gives an insight into current research activities on optimized grid operation methods, organized by voltage level, that support the integration of wind and solar and address related challenges in today’s power systems. This includes extra‑high voltage offshore systems, high‑voltage grids and medium/low‑voltage grids, with battery storage as a cross‑level element.

At extra‑high voltage, a digital‑twin approach for offshore wind clusters focuses on ancillary services. Wind production and regional demand forecasts are translated into service schedules at interconnection points and HVDC links. The approach considers interactions within clusters and onshore constraints and supports voltage control, congestion management, and reserve planning across the offshore-onshore boundary.

At high voltage, a curative operation concept is formulated for high voltage (110 kV) grids with strong wind infeed. It defines trigger logics, curative action sequences, and timing that use thermal operating margines after defined contingencies while respecting protection limits and clearance times. This shift from preventive measures to controlled curative actions enables a more efficient use of existing infrastructure and can accelerate the integration of new renewable energy plants and contribute to postponing grid expansion. Moreover, reactive power control at the high voltage level is presented that can further support the integration of renewable energy resources by ensuring voltages stay within applicable limits. Reactive power control is relevant for all voltage levels and also further discussed for lower voltage levels.

At medium and low voltage, a coordinated multi-level voltage and reactive power optimization scheme generates hierarchical setpoints for on‑load tap changers in secondary substations and reactive power. Using real-time grid measurements, the scheme maintains voltage limits at the LV level while supporting upstream MV reactive power requirements. Compared with local characteristic curves, the approach unlocks and utilizes reactive power flexibility across MV and LV levels more effectively and thereby increases hosting capacity for PV and new loads such as electric vehicles and heat pumps.

Battery storage is considered across voltage levels, including the assessment of grid hosting capacity for battery integration. Operating schemes are outlined for local voltage support, congestion relief, and balancing. These schemes are designed to respect grid constraints and fit within differing regulatory settings.

The methods presented serve as concrete examples from current research. Further operational approaches can complement them, including resilience assessments, modeling of controllable demand and further control concepts, which are also briefly discussed in the paper.

Taken together, the presented grid operation methods play a vital role in ensuring safe and reliable grid operation and in accelerating the integration of wind and solar. Careful cross‑voltage operation can address generation variability, manage emerging load patterns, and improve hosting capacity, thereby supporting the energy transition. At the same time, grid expansion remains essential and should proceed in parallel to address enduring constraints that cannot be fully resolved by optimized grid operation alone in the long term.