A Research and Development on an Active Voltage-Frequency Regulator (AVFR) Integrated with the Mechanisms of Exciter and Governor for an Isolated Wind-Driven Induction Generator System

This research is following the project: "Design of an advanced static synchronous compensator to improve dynamic excitation performance of an isolated induction generator system (NSC 96-2218-E-182-001)" supported by National Science Council in 2006. To mitigate voltage fluctuation for an isolated induction generator system under various loading conditions, an advanced STATCOM in the project was designed to be able to accommodate itself to the time-varying system frequency. However, for the wind-driven induction generator system, the output frequency may experience fluctuation due to random variations in load and wind speed. The purpose of this project is to design an active voltage-frequency regulator which integrated with the functions of the traditional exciter and governor of the synchronous generator such that constant voltage-frequency control under sufficient wind energy is achievable. In the WECS, voltage regulation can be reached by using the STATCOM to condition the reactive power flow. However, due to the high moment of inertia in the wind turbine, it is difficult to control the wind power by using the traditional speed governor. Pitch angle control is performed only to limit maximum output power at high wind speed. To attain constant voltage-frequency control for an isolated wind-driven induction generator system, an active voltage-frequency regulator will be developed in this project. The main configuration of the proposed system is a voltage-sourced inverter with a dynamic DC load. The objective of the dynamic DC load is to consume the surplus active power rapidly such that the control of the system frequency can be obtained. As regards the reactive power compensation, the output voltage control by means of the voltage-sourced inverter is well known the best way to reach the system voltage regulation. In this project, theoretical derivation and computer dynamic models will be built first in order to simulate the effects of various disturbances on dynamic performance. Then, the control gains of active power and reactive power will be coordinated in order to match the time constant of the WECS. Experiments will be conducted to verify the effectiveness and the performance of the active voltage-frequency regulator when the isolated IG is subject to the disturbances such as load and wind speed variations. Finally, the experimental results will be analyzed and compared with the simulation results.

Project ID:PB9709-4328
External Project ID:NSC97-2221-E182-059