Optimal FRT Compliance of Offshore Wind Power Plants in VSC-HVDC Connection based on Genetic Algorithms

Abstract

This paper proposes a new methodology for the optimal compliance of type-4 wind power plants in VSC-HVDC grid connection with the typical Fault-Ride-Through (FRT) requirements. Unlike the traditional chopper based solution, an improved offshore AC voltage droop FRT strategy, which is communication free and ensures robust faulted dynamic response is proposed to achieve FRT compliance. The calculation of the best parameters that enable successful FRT compliance is formulated as an optimization problem. The objective function aims at minimizing the electrical stresses imposed at the HVDC system and at the offshore wind power plants during the FRT and the post-FRT period, while simultaneously ensuring FRT compliance for the HVDC system and the wind power plants. The optimization is tackled based on an iterative procedure that combines dynamic modelling of the HVDC system and the connected offshore wind power plants, with a genetic algorithm based search process. Numerical results for a point-to-point connection that is extended to the three terminal HVDC grid connection case are demonstrated.