Single Wind Turbine Power Generation Systems

Abstract

For a power system with substantial power generation from wind farms, controllability of the wind farm power outputs is critical to power system reliability and economy. Both the active and reactive powers need to be maintained at appropriate levels. Indeed, recent experience with wind farm operation and research suggests that a wind farm should have at least two operating modes: maximum power tracking (MPT) and power regulation (PR). MPT is a traditional operating mode, aimed at enabling wind turbines in a wind farm to convert as much of the energy in wind to electrical energy as possible under normal operation conditions. PR, on the other hand, is concerned with adjusting the wind turbine power outputs as needed by power system reliability, or economic conditions. Being able to operate in either the MPT or PR mode is becoming increasingly important as the penetration of wind energy increases. In this chapter, we first introduce the basic structure of and a mathematical model for a variable-speed wind turbine with a doubly fed induction generator (DFIG), a widely used power generation technology today. This model may be used in the development of controllers for controlling the active and reactive power outputs of the wind turbine. Indeed, we also illustrate an application of the model to the design of a reconfigurable nonlinear controller, which enables the wind turbine to maximize its active power in the MPT mode, regulate its active power in the PR mode, switch between the two modes, and adjust its reactive power to achieve a desired power factor, while coping with uncertainties in most of its parameters. Finally, we demonstrate the effectiveness of the controller through simulation with a realistic wind profile.