Simulation programs are increasingly getting a work out in the design of wind turbines and wind farms. One reason: As the size and number of wind power plants (WPP) rises, planners must study how they affect power systems. And as the level of wind power penetration into the grid increases, there's a more critical need for reliable devices and a transmission grid that's well integrated.
Hydro-Quebec engineer Richard Gagnon recently gave a glimpse of current simulation practices at the Montreal utility. At Hydro-Quebec, the well-known Simulink program from The MathWorks, Inc. and an extension called SimPowerSystems help simulate and develop models of wind generators and validate modeling techniques for the simulating of WPPs. In particular, engineers there have modeled the doubly fed induction generators common to megawatt-scale turbines, as well as the associated filters, converters, and transformers. Simulink has also been used to model controls and the drive trains in such turbines.
At most utilities, though, there is more emphasis on modeling wind farms and WPPs than on modeling individual turbines. Fortunately, utilities needn't start from scratch.
Researchers at the National Renewable Energy Lab devised an equivalent representation of a WPP collector that interconnects wind turbines. NREL researchers used a specific large WPP as a case study, but say their concept can be tweaked so that it applies to any type of WPP. So utilities like Hydro-Quebec start with the NREL model and then adjust for the layout of the specific WPP in question, the size and type of conductors, and method of delivery (overhead or buried cables), all of which influence collector performance.
Gagnon says Hydro-Quebec engineers validated the NREL method of modeling WPPs using a combination of Matlab tools and Hypersim, a real-time power grid simulator that Hydro-Quebec devised. Hypersim runs on SGI Origin 350 and 3000 supercomputers and can simulate thousands of faults per day, analyzing them as tables or waveforms.
In verifying the NREL method, Hydro-Quebec engineers used simulation software to model a 109.5-MW WPP containing 75 1.5-MW turbines feeding a 34.5 kV collector system with 17 km of overhead lines and 62 km of cables. The results of the simulation, says Gagnon, shows the NREL method is adequate for a broad range of power system studies.
Utilities aren't the only ones using simulation. Turbine makers also use the software to iron out bugs controls. An example comes from Siemens Wind Power A/S where engineers devised a hardware-in-the-loop simulation for testing their wind turbine control software. Siemens puts out new releases of its wind turbine control packages quite frequently. To simplify the testing involved, engineers employed a National Instruments Corp. test management package called TestStand.
