Simulation of the global overvoltage control strategy in a off-shore wind farm with HVDC/Series layout

Abstract

This project is oriented, first of all, to give a global theoretical vision of the technology used in the interconnection between the different wind turbines of a wind farm (mainly these are Radial, Star, Ring or Parallel Series). in the deep sea and also, between these and the ground connection point with the electric transport network (mainly Medium Voltage Altern Current, High Voltage Alternative Current, Medium Voltage Direct Current and High Voltage Direct Current), where the distance between These are of a length (approximately 100km), such that, the systems used today in this type of facilities, are not viable in terms of technological limitations, or in terms of profitability, due to high investment what these would suppose. In addition, after the justification, by comparison of all existing designs, in terms of losses, cost of the driver and viability, it is deepened in the design that is considered most promising for the future of offshore wind farms, This is the Parallel / HVDC Series. Secondly, the construction of a DC / DC converter is performed to simulate the voltage and current control at the input thereof to ensure that the voltage and current values do not exceed the nominal work values of the generator or by example for these to fit a specific point of work (MPPT). Two converter models are designed, the first one is a converter using switches and the second with an average model in order to simplify the simulation and improve the behavior. Control design is part of this work. Third, we want to give a practical view of the selected design within the possibilities that this entails, by means of a computational simulation through Matlab / Simulink. This simulation consists in the coupling of 4 wind turbines in series, and the realization of the global control of the overvoltage limit. The parts that make up this simulation, its function and the dimensioning of the control parameters are described. Finally, the results of the simulation are presented considering several cases (such as failure in a wind turbine and reduction of the power captured from two of the wind turbines). Finally, the final conclusions are made by comparing the global control system with the traditional control system and the following final conclusion is extracted: The design analyzed in this project is proving to be, in several research projects, the most feasible option today in day to access the wind energy sources available in the deep sea, where the distance from this respect the point of connection to the ground is equal to or greater than 100km.