Performance Analysis of Fractional-Order PI-Based Controller for Variable Speed Hybrid Standalone WECS

  • Anjana JainEmail author
  • R. Saravanakumar
Conference paper
Part of the Smart Innovation, Systems and Technologies book series (SIST, volume 161)


The presented work in the paper shows a comprehensive analysis of fractional-order PI (FOPI) controller based voltage and frequency (VF) control of variable speed hybrid-standalone wind-energy-conversion-system (WECS). The system comprises of two major components: (1) permanent-magnet-synchronous-generator (PMSG), (2) battery-energy-storage-system (BESS). For standalone operation, the frequency and magnitude of voltage need to be controlled at the load terminals. DSOGI-PLL (Dual-second-order-generalized-integral based phase-locked-loop) is designed to track the frequency of the system. Fractional-order (FO) controllers provide robustness to Voltage Source Converter (VSC) due to their fractional characteristic. FOPI (PIλ) controller has an extra degree-of-freedom λ (order of integral) with its proportional gain (Kp) and integral gain (Ki). Simulation analysis is carried out in MATLAB/Simulink for PMSG-BESS based WECS. Proposed controller’s performance is evaluated for varied conditions of operation. FOPI based controller is significantly minimizing the peak overshoot and settling time for the terminal voltage, also it improves the transient response of the system.


Standalone WECS PMSG BESS VSC Bi-directional converter PLL Fractional-order PI 






\(A^{{\prime }}\)

Swept-area of turbine blades

\(\lambda^{{\prime }}\)

Tip-speed-ratio of wind turbine

\(C_{\text{p}}^{{\prime }}\)

Power-coefficient of wind turbine

\(\beta^{{\prime }}\)



Turbine power


Rotational-speed of rotor


Radius of wind turbine


Electrical angle


Turbine torque


Generator’s electromagnetic torque




Mechanical speed of rotor


Electrical speed of rotor


Moment of inertia


Viscous friction coefficient


Stator winding resistance


Direct axis stator inductance


Quadrature axis stator inductance


Flux linkage


Direct-axis stator voltage


Quadrature-axis stator voltage


Direct-axis stator current


Quadrature-axis stator current

\(\Gamma (x)\)

Gamma function
















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© Springer Nature Singapore Pte Ltd. 2020

Authors and Affiliations

  1. 1.Department of Electrical & Electronics EngineeringAmrita School of Engineering, Bengaluru, Amrita Vishwa VidyapeethamBengaluruIndia

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