Titel: Development of a Method for Evaluation of Wind Turbines Ability to Fulfil Swedish Grid Codes, Elforsk rapport 09:25
Författare: Massimo Bongiorno & Andreas Petersson
Utgivare: Elforsk, Vindforsk
Årtal: 2009
Ämnesord: infrastruktur
Sökord/Keywords: grid-codes, VSC, voltage.
Rapport
Sammanfattning/Abstract: A large-scale integration of wind power will take place in the Swedish grid if all proposed wind power projects will be built. In total, there are plans for
25.000 MW wind power that shall be connected into the Swedish power system. If such amount of wind power is installed it will significantly affect the power system as the present installed power production capacity is in the same range. When Svenska Kraftnät (the Swedish state utility) updated their legislations or grid code for production plants the new version also included wind power.
In this report a validation plan for grid-code compliance tests has been developed. The validation plan is essential since a good validation plan leaves little or no room for different interpretations regarding how each requirement in a grid code shall be validated. One intention is that the developed validation plan could serve as a basis when discussing or evaluating grid code compliance of the Swedish grid code. The second aim of the validation plan is to investigate the design and the performance of a voltage source converter (VSC) based test equipment for testing single wind turbines. The proposed
VSC-based test equipment is similar to that of the Tjæreborg HVDC light test and demonstration system, and consists of two back-to-back connected VSCs that emulate the grid and the grid connection of a single wind turbine installation. The VSC-based test equipment is versatile since it has the possibility to emulate the grid and vary both the voltage and frequency independently.
The most demanding test, for the VSC based test equipment, is the emulation of short circuits leading to voltage dips. This since the test equipment must be designed for the fault current provided by the wind turbine. The fault current from wind turbines can be several times higher than the rated current of the wind turbine.
Finally, a prototype of the VSC based test equipment has been implemented in the power systems laboratory at Chalmers University of Technology. It has been shown, experimentally, that the proposed test equipment can be used for testing the Swedish grid code by applying different voltages and frequencies to the wind turbine. Moreover, the test equipment can apply very fast changes in the voltage in order to emulate “short circuits” and thereby resemble the low voltages that occur in the grid.