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energetica-india-55

WIND ENERGY INGETEAM POWER TECHNOLOGY S.A. Optimal Crowbarless solution for connecting Doubly Fed Induction Generators into weak grids Wind power penetration into the power generation system has substantially increased during the last twenty years. This fact makes that the power quality and stability of this generation system is becoming increasingly important. For that reason, the grid codes, which establish the requirements that all generation systems must fulfill in order to be allowed to connect to the grid, have been updated in order to guarantee the stability of the grid. In the recent past, wind turbines were allowed to disconnect from the grid when transients in grid voltage could jeopardize the integrity of their elements, especially the power converter. However, nowadays, due to the large amount of wind power installed in the generation system, this is no longer allowed. With such increase in installed power, the wind industry faces now the challenge of the suitable integration of the wind turbine into the grid, which main issues are the following: • Large distances between generation and load points: In many occasions, the areas with suitable wind resources are not close to those areas where the energy is being consumed. Series and parallel compensation solutions are installed in order to increase the capacity of long transmission lines. These systems can present issues related to Sub-Synchronous Resonances (SSR) and Sub-Synchronous Control Interaction (SSCI), among others. • Low capacity of the transmission lines: These grids are the so-called weak grids. It is defined as a grid which presents a low Short Circuit Ratio (SCR) that in a wind farm is the relation between the short circuit capacity of the grid at the common coupling point of the farm and the rated power capacity of the wind farm. Basically, these are grids in which the voltage fluctuates with Active and Reactive power flow. • Fault Ride Through events: These events are usually caused by short circuits produced in the grid. Generation systems must be able to keep connected during these events in order to support the grid stability. Wind power in India has also experienced a huge growth within the last years, being the installed capacity 22,465MW in 2014, with an average increase of 21% per year according to GWEC report. This increase in generation capacity must be accompanied by a suitable conditioning in the transmission systems. Otherwise, the electric system stability could be compromised. In this regards, due to its rapid growth, the Indian electricity system faces some of the challenges described in terms of grid stability. The Doubly Fed Induction Generator (DFIG) topology is proven as the most efficient and cost-competitive topology for wind turbines rated up to 3.5MW. That is the reason why it is being currently the most installed topology. However, its low grid integration capability jeopardizes the use of this type of conversion system, due to its high sensitivity to grid voltage transient, in which high voltages and currents appear in the rotor side of the generator, endangering the Ingeteam Crowbarless Power Converter power converter connected to it. This is 40 energética INDIA · ENE | FEB16


energetica-india-55
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