Hydroelectric Operation Optimization and Unexpected Spillage Indications

Abstract

It is widely known that hydroelectric power plants benefit from optimized operation schedules, since the latter prevent water and, therefore, monetary wastes, contributing to significant environmental and economic gains. The level of detail on the representation of such systems is related to how far ahead the planning horizon is extended. Aiming at the very short-term optimization of hydroelectric power plants, which usually requires the most detailed models, this paper addresses an undesired effect that, despite being already mentioned in the literature, has not been properly explored and explained yet. This effect is given by the indication of spillage by the optimizer, even when the reservoir does not reach its maximum capacity. Simulations implemented in Julia language using real power plant data expose this phenomenon. Possible ways to circumvent it are presented. Results showed that, in specific cases, spillage allows the achieving of more efficient operating points by reducing the gross head and increasing the amount of water that flows through turbines. Furthermore, it was verified that applying water outflow-based objective functions prevents undesired spillage indications, despite causing machines to operate at lower efficiency levels, compared with the utilization of power losses-based objective functions.

Evaluating the Impact of Streamflow Rating Curve Precision on Firm Energy of Hydropower Plants

“…In this context, study [22] evaluates techniques of fitting a hydraulic turbine efficiency curve. In addition, studies in [23,24] evaluate techniques for predicting and prevent undesired spillage.…”

“…At the end of each stage, the variable Z sup (upper limit) is increased by the value corresponding to the immediate cost, Equation (22). Moreover, at the end of the forward process Z sup will be equal to the sum of the immediate costs, Equation (23).…”

Spillage Forecast Models in Hydroelectric Power Plants Using Information from Telemetry Stations and Hydraulic Control

“…In [6], the focus is on the long-term generation scheduling problem. Abritta et al [7] performed the short-term optimization of HPP considering the indication of spillage by the optimizer. The meta-heuristic particle swarm optimization and network flow are used in [8] to obtain the optimal solution for reservoir operation rules, through water transfer between basins.…”