Abstract
A large-scale power system breakdown in the United Kingdom caused blackouts in several important cities, losing about 3.2 percent of the load and affecting nearly 1 million power users on 9 August 2019. On the basis of the accident investigation report provided by the UK National Grid, the specific reasons for the sub-synchronous oscillation of Hornsea wind farm were analyzed. The Hornsea wind power system model was established by MATLAB simulation software to reproduce the accident. To solve this problem, based on the positive and negative sequence decomposition, the control strategy of grid-side converter of doubly-fed induction generator is improved to control the positive sequence voltage of the generator terminal, which can quickly recover the voltage by compensating the reactive power at the grid side. Consequently, the influence of the fault is weakened on the Hornsea wind farm system, and the sub-synchronous oscillation of the system is suppressed. The simulation results verify the effectiveness of the proposed control strategy in suppressing the sub-synchronous oscillation of weak AC wind power system after being applied to doubly-fed induction generator, which serves as a reference for studying similar problems of offshore wind power.
Highlights
Based on the above analysis, combined with the idea of positive and negative sequence decomposition to solve the sub-synchronous oscillation accident caused by an asymmetric fault in the Hornsea wind farm, the control of the grid-side converter is improved
This study proposed the control strategy to avoid sub-synchronous oscillation acciThis study proposed the control strategy to avoid sub-synchronous oscillation accident by considering a case study of the Hornsea wind power system accidental incident
The accident response of a sub-synchronous oscillation event in the Hornsea wind power system is mimicked in MATLAB simulation according to the information provided in British official reports
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The Hornsea wind power system model simulation is built in MATLAB/Simulink software, reproducing the whole sub-synchronous oscillation accident in this paper It provides a research basis for improving its control strategy to suppress the sub-synchronous oscillation accident. Based on the above analysis, combined with the idea of positive and negative sequence decomposition to solve the sub-synchronous oscillation accident caused by an asymmetric fault in the Hornsea wind farm, the control of the grid-side converter is improved. While maintaining the stability of the DC bus voltage, the control of the positive sequence voltage of the generator terminal is increased, the reactive power on the grid side is compensated to recover the voltage quickly, the influence of the system fault on the Hornsea wind farm is weakened, and the sub-synchronous oscillation of the system is suppressed. MATLAB posed strategy.software to reproduce the accident and verify the effectiveness of the proposed strategy
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