Multi-Timescale Coordinated Configuration and Operation of Hybrid Energy Storage for Wind-Solar-Cascade Hydropower Systems

[Objective] To mitigate the challenges posed to power grid security by the randomness and volatility of high-penetration wind and solar power output in clean energy bases， and to promote their efficient integration and advance carbon neutrality goals， multi-timescale nested optimization method for energy storage capacity configuration that considers the coordination of cascade hydropower and hybrid energy storage is proposed in this paper. [Methods] The proposed method accurately characterizes head loss， ramping constraints， and vibration safety intervals of hydropower units in a wind-solar-cascade hydropower system， and develops a two-stage optimization model. In the first stage， coordinated scheduling of cascade hydropower and pumped storage is employed to smooth long-period， large-amplitude fluctuations of wind and solar power. In the second stage， the fast response capability of electrochemical energy storage is utilized to compensate for short-term high-frequency， small-amplitude power disturbances. [Results] The simulation results demonstrate that the proposed method can fully exploit the coordinated advantages of hydropower regulation capability and hybrid energy storage. By leveraging pumped storage to smooth long-period large fluctuations and electrochemical energy storage to compensate for short-term high-frequency disturbances， a functional division and capacity matching between the two are achieved. Their complementary advantages lead to an optimal final configuration， which effectively suppresses power fluctuations across the full time scale of the system. As a result， the system’s curtailment rate is reduced to 0.10%， the load matching degree is improved to 99.85%， and the required rated power of the electrochemical energy storage accounts for less than 1% of the total installed capacity of the base. [Conclusions] The proposed optimization configuration method achieves synergistic complementarity between cascade hydropower and hybrid energy storage across multiple time scales， significantly improves wind and solar power integration and load matching capability， and greatly reduces the required capacity of electrochemical energy storage. It provides reliable technical support for energy storage capacity optimization and efficient renewable energy integration in clean energy bases.