New Synthetic Inertia Control for Wind Energy Conversion System

Abstract

Participation of modern variable-speed wind turbine generators in system frequency support has gained much attention from various transmission system operators to increase renewable technology hosting capacity in their power networks. A supplementary control loop is added to enable the modern variable-speed wind turbine generators to act as traditional alternators and utilize their hidden inertia. However, conventional natural inertia control strategies, such as typical ROCOF-dependent and ∆f-dependent controllers, have limited effectiveness in diverse power system operating and contingency conditions. In this work, the two variants of typical natural inertia controllers are first discussed. Then, two novel adaptive control structures, adaptive ROCOF-dependent and adaptive ∆f-dependent, are proposed. The proposed controllers adaptively change their gains based on the ∆f and ROCOF signals, respectively, while also considering the wind speed at which the sudden load changes occurred. The results illustrate the superiority of the proposed controllers in handling severe operating condition changes. Furthermore, sensitivity analysis for the typical and proposed controllers shows that the proposed controllers are the best controllers that can be used under different wind penetration levels, wind speeds, and sudden load changes in terms of various key performance indicators, especially frequency nadir, maximum ROCOF, and maximum deviation in frequency.INDEX TERMS Power Systems, frequency control, frequency deviation, rate of change of frequency (ROCOF), variable speed wind turbine, inertial response, dynamic performance, sudden load change, wind.