Research of Frequency Coordinated Control Strategy Based on Variable De-loading Level for D-PMSG Wind Turbine

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ORIGINAL ARTICLE

Research of Frequency Coordinated Control Strategy Based on Variable De‑loading Level for D‑PMSG Wind Turbine Mudan Li1,2   · Yinsong Wang1,2 Received: 23 June 2020 / Revised: 19 August 2020 / Accepted: 18 September 2020 / Published online: 9 October 2020 © The Korean Institute of Electrical Engineers 2020

Abstract A new frequency coordinated control strategy based on the variable de-loading level for a D-PMSG wind turbine is proposed. First, the D-PMSG wind turbine model and control system model are established. Second, the de-loading control principle of the D-PMSG wind turbine is described, the variable de-loading level control strategy is analyzed according to different wind speeds and additional inertial control is introduced. Then the frequency coordinated control strategy combining variable de-loading level control and additional inertial control is designed for different power reserve areas. Finally, a D-PMSG grid-connected simulation system is built to verify the rationality and accuracy of the frequency coordinated control strategy. Keywords  D-PMSG · Wind turbine · Frequency modulation · Variable de-loading level control · Coordinated control

1 Introduction As a clean energy source with substantial development prospects, wind energy has been globally recognized as the best solution for improving energy security and promoting lowcarbon economic growth [1, 2]. However, due to the uncertainty of wind speed, wind power is random and intermittent, and large-scale grid-connected wind power will affect the power system frequency stability and increase the difficulty of frequency control [3, 4]. To enhance the ability of the grid to accept wind power, it is important to heighten the wind power frequency modulation and control capabilities. Directly driven wind turbines with permanent magnet synchronous generators (D-PMSGs) without troublesome gearboxes have attracted considerable attention due to their high efficiency, high reliability, competitive cost and wide operating ranges [5–7]. In the maximum power point tracking (MPPT) control mode, the D-PMSG hardly contributes to the system inertia and shows weak support for the frequency stability owing to the decoupling of the rotor speed and system frequency. Large-scale grid-connected wind * Mudan Li [email protected] 1



Science and Technology College, North China Electric Power University, Baoding, China



College of Control and Computer Engineering, North China Electric Power University, Baoding, China

2

power inevitably causes a lower system inertia and an insufficient frequency modulation ability [8–10]. Therefore, it is of great theoretical and practical significance to study the D-PMSG frequency control strategy for participation in the grid frequency modulation. To improve the frequency modulation capability and strategy for grid-connected wind power, scholars worldwide have performed many studies. Based on the system frequency variation, the inertial response of synchronous generators can be simulated, and the wind turbine rot