Optimal Short-Term Operation of a Cascaded Hydro-Solar Hybrid System: A Case Study in Kenya

Abstract

In this paper we propose an optimal dispatch scheme for a cascaded hybrid hydro-solar power system, i.e., a hydroelectric system coupled with solar generation, that maximises the head levels of each dam, and minimises the spillage effects. As a result more water is stored in the dams to meet a given amount of energy providing more flexibility to the system in dry months. This dispatch scheme is based on the development of a simplified hydroelectric power system model which has low computational burden and may be implemented for the short-term operation of a cascaded hydro-solar hybrid power system. To this end, the non-convex relationships that describe the system physical constraints, e.g., hydroelectric power output, are transformed into affine relationships; thus reducing the computational complexity. The transformations are based on the construction of convex envelopes around bilinear functions, piecewise affine functions, and exploitation of optimisation properties. We validate the proposed framework and quantify the benefits of coupling hydroelectric and solar resources in terms of live water volume in dams and amount of solar a system may withstand with the Tana river cascade located in Kenya through an analysis of incorporating actual system data.

A Short-Term Optimal Scheduling Model for Wind-Solar-Hydro Hybrid Generation System With Cascade Hydropower Considering Regulation Reserve and Spinning Reserve Requirements

“…Error rate is an important index to judge the solution accuracy, which reflects the gap to the most accurate results. The variation of error rate and computation time with the number of subintervals for (12) are shown in FIGURE 12 and FIGURE 13. For the sake of analysis, we assume that qH and v are equally divided, i.e., m=n.…”

“…Results indicate that their coordinated operation is conducive to the minimization of wind power curtailment. Dimitra et al [12] propose an optimal dispatch scheme for a hydroelectric system coupled with solar generation, and the simulation results verify the coupling of hydropower and solar power is beneficial due to the negative correlation of rain and sunshine. Shen et al [13] presents a methodology for hydrothermal system generation scheduling considering multiple provincial peak-shaving demands.…”

Optimal Dispatch of Pumped Storage Hydro Cascade Under Uncertainty

“…is a good approximation of (1) as shown in [8]. The power output of each hydroelectric power plant i ∈Ñ is constrained by a minimum and a maximum output, i.e., P m i ≤P i (t) ≤ P M i , for all t ∈ T .…”

“…We represent the cascading constraints by (6)- (8) and (14) for the hydroelectric plants and the pumped storage hydro plants, respectively; the relationship between the head level and live volume by (21); the power balance by (25). The lower and upper bounds of decision variables are included through (4)- (5), and (9).…”

Research on Energy Storage Optimization for Large-Scale PV Power Stations under Given Long-Distance Delivery Mode

“…Recent studies and practices have shown that complementary energies, such as energy storage and hydropower, are effective measures to reduce the output fluctuation of a PV power plant and achieve complementary output to meet the grid connection requirements. Hydropower is the most reliable complementary energy because of its low cost, high installed capacity, good regulation performance, and high reservoir storage capacity [17][18][19][20][21]. However, hydropower stations have higher requirements on the construction sites and environmental factors, such as abundant water sources, rich precipitation, good geological foundation, and large difference in elevation.…”