No abstract

The harmonic amplitude may exceed the limit when the large scale of wind farm is connected to the weak AC system through AC submarine cable. The harmonic with high amplitude will endanger the safety of power equipment, and even affect the normal integration of large-scale wind farm. This paper takes an actual offshore wind power connected to the system through AC submarine cable as an example. On the basis of building the model of the system in the PSCAD/EMTDC simulation software. The simulation calculation is systematically carried out. The effect of multiple factors on the harmonic characteristics is analyzed. The preliminary explanation for the harmonic amplitude out of limit is given for the actual large scale of wind farm connected to the weak AC system through AC submarine cable.

Electromagnetic simulation (EMS) plays an important role in the evaluation of subsynchronous resonance (SSR). To meet the requirement of practical engineering, this paper discusses how to improve the modeling method of SSR-EMS in three important aspects, i.e., the shaft system of turbine generator, the series compensation and the supplementary excitation damping controller (SEDC). Thus a systematically improved EMS model was put forward, which includes a lumped mass-spring model with adjustable and non-linear mechanical damping, a series compensation model incorporating MOV with the gap protection logic and an engineering model of SEDC to reflect the dynamics of the power-electronic exciter. The developed model overcomes the shortage of the traditional one and is applicable to the accurate analysis on SSR stability, transient torque and fatigue expenditure when the system experiences large disturbances. The proposed method is then used for the simulation of a real SSR event caused by a short-circuit fault in the Shangdu series-compensated power system. The simulation results are compared with the field measurements and a good consistence is found. Consequently, the improved EMS model is proved to be applicable, accurate and effective for SSR analysis in practical engineering.