Grid disturbance resilience and stability improvement of grid-connected wind power plants

Abstract

Integrating wind power plants (WPPs) into the power grid presents significant issues related to grid disturbance resilience and stability. New grid codes (GCs) now require WPPs to support voltage and frequency stability during disturbances like in conventional power stations. This research addresses this need by developing and validating a control strategy for grid-connected WPPs (GCWPPs) to enhance resilience and stability during voltage and frequency fluctuations and faults. To achieve this, a comprehensive control strategy is developed. This controller enhances grid disturbance resilience in WPPs without additional hardware. The proposed controller enables GCWPPs to operate in two modes: normal operation and fault mode during disturbances. For voltage stability, the GCWPP is equipped with a resilience and fault immunity (RFI) control strategy. RFI includes a rapid disturbance detection method that enables the GCWPP to switch immediately to fault mode when a fault occurs. In such scenarios, the DC-link voltage on the grid-side and rotor-side AC current increase, potentially damaging WPP components and risking disconnection from the grid. To prevent this, RFI provides protection for both the rotor-side and grid-side converters. Additionally, to stabilize grid voltage, RFI injects reactive power based on the fault level, in line with recent GCs requirements. For frequency stability, the study introduces an automatic power control (APC) strategy for GCWPPs, enabling wind turbines to respond to frequency deviations like conventional generators. The APC stabilizes frequency within the nominal range during disturbances. The findings of this research demonstrate that the proposed control strategies enhance grid disturbance resilience and stability in GCWPPs. The simulation results show notable improvements in voltage and frequency stability. The proposed controllers effectively mitigate the impact of grid disturbances, ensuring reliable operation under changing conditions. Additionally, the RFI and APC controllers quickly restore system parameters to pre-disturbance levels once the issue is resolved, offering a promising solution for improving WPP performance and contributing to a more reliable and efficient electricity grid.