Implementations and Evaluations of Wind Turbine Inertial Controls With FAST and Digital Real-Time Simulations

This paper presents a novel simulation approach to evaluate new ancillary service controls in the context of large-scale wind power integration. We adopt and compare different types of turbine inertial control methods with the proposed modifications to cope with realistic wind conditions in the field. The simulation procedure is started with the software-based simulation, in which we employ the high-fidelity wind turbine simulator FAST that models a real three-bladed controls advanced research turbine (CART3). The advantages of using FAST are that it can provide convincing simulation results and address the interactions between turbine electrical and mechanical systems. The developed controller model is then rapidly prototyped for the real-time simulation with the hardware-in-the-loop scheme. CART3 will respond to a virtual frequency event triggered in the emulated electric grid modeled in a digital real-time simulator. The introduced simulation platform streamlines the procedure of designing turbine auxiliary controls, and these simulations results give insights on the turbine controls and their impacts on the interconnected power system, as well as the effects on turbine mechanical components. For example, the results indicate that the inertial controls tend to reduce the out-of-plane mechanical loadings in region 2, while such loadings are dominated by the pitch actions in region 3.

I. Introduction

The worldwide wind energy is experiencing a steady increase in the last few decades. Wind power has represented 33% of all U.S. power capacity additions since 2007, and this percentage is still increasing with the current wind power growth rate [1]. According to the Wind Technology Market Report, the wind power grew at a rate of 12% in 2015 and stands at nearly 74 GW, meeting an estimated 5.6% of U.S electricity demands [2]. The increased capacity of individual wind turbine poses challenges on the turbine controls and wind power plants (WPPs) integration. The basic turbine control system should account for the increased turbine structural flexibility through the generator torque and blade pitch control loops, so an efficient energy production with a reduced levelized cost of energy can be achieved [3]. On the other hand, integrating high levels of wind power into an electric grid requires significant changes to power system planning and operations to ensure continued reliability [4]. The testing procedures in international standards (e.g., IEC 61400) should be performed to ensure that the WPP complies with the grid codes in terms of frequency responsive controls and voltage controls [5].