Modeling and Simulation of a Hydrokinetic Generation Connected to the Electricity Grid

Abstract

As conventional hydroelectric power plants are reaching physical and environmental constraints, hydrokinetic turbines, which use only a natural flow from the rivers analogous to wind generation, may become a growing solution to overcome these limits. There is still an unexplored hydropower potential, which is more ecologically correct to take advantage of in a distributed and not dammed way. This paper describes a power converter topology and a control system for a hydraulic turbine to inject power into the grid proportional to the river flow rate. The control system is composed of: an MPPT (Maximum Power Point Tracking), which measures the voltage and current in the DC bus and generates a voltage reference of the DC link for the maximum power of the turbine-generator system; by the DC link voltage controller, which provides a reference for the control of electric current injection into the network; and by the single-phase instantaneous current control of the grid-connected voltage source inverter. One of the contributions consists of identifying the operating conditions and limits of the whole system, composed of the hydraulic turbine, the electric generator, and the power converter. The same methodology may be applied to design specific sets of a turbine-generator-converter system for each application.