Equivalent models are essential for time-domain simulation and harmonic stability evaluation of renewable power plants.Such harmonic instability may co-occur at the plant-level and unit-level,or it may only occur at t...Equivalent models are essential for time-domain simulation and harmonic stability evaluation of renewable power plants.Such harmonic instability may co-occur at the plant-level and unit-level,or it may only occur at the unit-level,manifesting as local resonances.However,conventional equivalent methods can only simulate plant-level instability,but cannot consider such unit-level instability.To address this problem,the main contributions of this paper are as follows:1)Based on the impedance matrix and the eigenvalue analysis,the reason why conventional equivalent methods cannot accurately simulate unitlevel stability is studied.2)A double-machine equivalent method is proposed.The model used in this method is a minimumscale equivalent model capable of simulating plant-level and unit-level stability,simultaneously.It uses two single-machine models to represent a generation cluster containing N generation units.A single-machine model M_(1) represents N—1 generation units for simplification,while another single-machine model M_(2) represents the remaining one generation unit for simulating unitlevel stability.3)Furthermore,a practical improvement approach of the double-machine equivalent method is proposed for taking into account operating point differences and complex connection conditions.Finally,the proposed method is verified by simulations and experiments.展开更多
基金supported by the Joint Funds of the National Natural Science Foundation of China(U23A20655)the Science and Technology Tackling Plan Project of Anhui Province(202423h08050008)the Science and Technology Project of State Grid Anhui Electric Power Co.,Ltd.(SGAHDK00CNJS2500397).
文摘Equivalent models are essential for time-domain simulation and harmonic stability evaluation of renewable power plants.Such harmonic instability may co-occur at the plant-level and unit-level,or it may only occur at the unit-level,manifesting as local resonances.However,conventional equivalent methods can only simulate plant-level instability,but cannot consider such unit-level instability.To address this problem,the main contributions of this paper are as follows:1)Based on the impedance matrix and the eigenvalue analysis,the reason why conventional equivalent methods cannot accurately simulate unitlevel stability is studied.2)A double-machine equivalent method is proposed.The model used in this method is a minimumscale equivalent model capable of simulating plant-level and unit-level stability,simultaneously.It uses two single-machine models to represent a generation cluster containing N generation units.A single-machine model M_(1) represents N—1 generation units for simplification,while another single-machine model M_(2) represents the remaining one generation unit for simulating unitlevel stability.3)Furthermore,a practical improvement approach of the double-machine equivalent method is proposed for taking into account operating point differences and complex connection conditions.Finally,the proposed method is verified by simulations and experiments.
