회전자 속도에 따라 변하는 게인에 기반한 가변속 풍력발전기 출력 평활화

Abstract

Abstract - In a power grid that has a high penetration of wind power, the highly-fluctuating output power of wind turbine generators (WTGs) adversely impacts the power quality in terms of the system frequency. This paper proposes a power smoothing scheme of a variable-speed WTG that can smooth its fluctuating output power caused by varying wind speeds, thereby improving system frequency regulation. To achieve this, an additional loop relying on the frequency deviation that operates in association with the maximum power point tracking control loop, is proposed; its control gain is modified with the rotor speed. For a low rotor speed, to ensure the stable operation of a WTG, the gain is set to be proportional to the square of the rotor speed. For a high rotor speed, to improve the power smoothing capability, the control gain is set to be proportional to the cube of the rotor speed. The performance of the proposed scheme is investigated under varying wind speeds for the IEEE 14-bus system using an EMTP-RV simulator. The simulation results indicate that the proposed scheme can mitigate the output power fluctuation of WTGs caused by varying wind speeds by adjusting the control gain depending on the rotor speed, thereby supporting system frequency regulation.Key Words : Power smoothing, Rotor speed-dependent gain, Releasable kinetic energy, Frequency deviation loop.†Corresponding Author : Dept. of Electrical Engineering, WeGAT Research Center, and Smart Grid Research Center, Chonbuk National University, Korea E-mail : yckang@jbnu.ac.kr* Dept. of Electrical Engineering, Chonbuk National University, KoreaReceived : February 23, 2016; Accepted : March 1, 2016