A multi-model multi-objective robust damping control of GCSC for hybrid power system with offshore/onshore wind farm

In the recent decade, the power network has experienced a remarkable energy transition due to the large-scale integration of wind energy resources, especially converter-interfaced modern wind turbines. The increasing/ decreasing wind penetration, on the other hand, unexpectedly affects the low frequency oscillations of the modern power grid. In this context, the proposed work adopts a multi-model multi-objective robust control framework to design a supplementary damping controller for the gate-controlled series capacitor (GCSC) to stabilize the hybrid power system with a permanent magnet synchronous generator (PMSG)-based off-shore wind farm (OSWF) and a doubly-fed induction generator (DFIG)-based onshore wind farm (ONWF). A bilinear matrix inequality (BMI) optimization problem, formulated as multi-objective synthesis considering H2/H infinity performance along with pre-defined pole placement, is presented for the GCSC control design, which is solved by a two-step linear matrix inequality (LMI) approach. In addition, all LMI constraints are constructed based on the multi -model control framework to incorporate multiple operating conditions. Afterward, the significant improve-ment in the damping characteristics of the closed-loop system, covering a wide operating range, is confirmed using eigenvalue analysis. The effectiveness of the scheme is validated using two case studies based on the hybrid power system, subject to various disturbances and uncertainties. The simulation results show the robustness and higher damping performance of the proposed multi-model strategy, compared to a conventional and a robust damping controller, for mitigating power system oscillations alongside voltage fluctuations of the wind farms.

Automated summary

This study investigates the impact of the large-scale integration of wind energy resources on low-frequency oscillations in the modern power grid. A multi-model multi-objective robust control framework is proposed to design a supplementary damping controller for stabilizing a hybrid power system with a permanent magnet synchronous generator-based offshore wind farm and a doubly-fed induction generator-based onshore wind farm. The optimization problem is formulated as a bilinear matrix inequality considering H2/H infinity performance and solved through a two-step linear matrix inequality approach. The effectiveness of the proposed strategy is validated through simulation studies.