Primary Frequency Stability Support of a DFIG in Association With Pitch Angle Control

Xiuli Si,Yien Xu,Feng You,Xiaoxin Wu,Dejian Yang,Hongliang Yuan

doi:10.3389/fenrg.2021.798037

Abstract

For an electric power grid that has large penetration levels of variable renewable energy including wind generation and photovoltaics, the system frequency stability is jeopardized, which is manifest in lowering frequency nadir and settling frequency. This paper suggests an enhanced primary frequency response strategy of a doubly-fed induction generator (DFIG) in association with pitch angle control. The DFIG works in de-loaded operation with a certain reserve power via pitch angle control prior to disturbances for frequency regulation. To address this, a function of the pitch angle is employed that decreases the pitch angle with time to slowly feed the active power to the power gird. The simulation results demonstrate the effectiveness and feasibility of the proposed primary frequency response strategy including the settling frequency and frequency nadir.

Highlights

When disturbances occur in a power system, the conventional synchronous generators (CSGs) intrinsically release kinetic energy in the rotor to compensate for the power imbalance as an inertial response; as a result, the system frequency declines (Kundur, 1994; Yang et al, 2018)
This study suggests an enhanced PFR strategy of a doublyfed induction generator (DFIG) based on pitch angle control to boost the settling frequency and maximum frequency deviation
The DFIG works in de-loaded operation with a certain reserve power for frequency regulation prior to disturbances

Summary

INTRODUCTION

When disturbances occur in a power system, the conventional synchronous generators (CSGs) intrinsically release kinetic energy in the rotor to compensate for the power imbalance as an inertial response; as a result, the system frequency declines (Kundur, 1994; Yang et al, 2018). When CSG4 generates 65 MW is tripped out from the electric power gird, the maximum frequency deviation for the DFIG without PFR is 0.539 Hz; in this case, there is no change on the pitch angle and the output of the DFIG. The improvements of the maximum frequency nadir for the proposed enhanced PFR strategies with different Δt are higher by 0.002 and 0.001 Hz in comparison with no PFR strategy, respectively, since the output power of the DFIG gradually increases and the rate of output power of the DFIG for the FIGURE 10 | Results for case 3. The DFIG with the proposed enhanced PFR strategy increases it output power from 133.6 to 148.4 MW with various rates by decreasing the pitch angle from 1.53° to 0° during 3.0 and 6.0 s, respectively. As the growing wind power penetration levels, the proposed PFR strategy can improve the frequency maximum frequency deviation and settling frequency in comparison with low wind penetration levels

CONCLUSION

DATA AVAILABILITY STATEMENT