This study addresses power system flexibility challenges in Kazakhstan and Uzbekistan under large-scale integration of variable renewable energy (VRE), specifically utility-scale wind and solar generation. By 2032, installed VRE capacity is projected to exceed 30 GW across the two countries, fundamentally changing system operation within the Central Asian interconnected grid, which is characterized by limited maneuverable generation, constrained transmission corridors, and centralized dispatch practices. Increasing shares of large-scale wind and solar significantly intensify residual load variability, ramping needs, and balancing requirements.

The research is based on original dispatch and grid modeling using real system data and projected scenarios for 2028–2032. The methodology includes residual load analysis, balancing reserve estimation, and assessment of operational constraints of thermal and hydropower units. Modeling results show that residual load becomes negative for up to 1,300–1,400 hours per year, requiring exports, storage charging, or curtailment. Balancing reserve requirements increase substantially, reaching about 4,200 MW upward and 3,300 MW downward in Uzbekistan by 2032.

The results demonstrate that existing generation assets are insufficient to ensure reliable system operation under high penetration of utility-scale wind and solar. Downward regulation emerges as a critical constraint, leading to increased renewable curtailment and operational risks during low-demand periods. The modeling indicates that several gigawatts of battery energy storage systems (on the order of 3–5 GW with multiple hours of storage) and additional flexible capacity, including potential pumped storage hydropower, will be required. Reinforcement of transmission infrastructure, including expansion of cross-border corridors by several hundred kilometers and increased transfer capacity, is also necessary to enable regional balancing.

The relevance of the study lies in its direct connection to ongoing energy transition processes and planned electricity market reforms in Central Asia. High VRE penetration increases the importance of balancing markets, flexibility services, and transparent cross-border coordination.

The paper concludes that a coordinated approach combining investments in storage, grid expansion, and market-based balancing mechanisms is essential for integrating large-scale wind and solar while maintaining system reliability and economic efficiency.

Nature of the work: original analysis based on real system and modeled data.

Level of expertise: research project.