Brian Parsons

Effect of Variable Speed Wind Turbine Generator on Stability of a Weak Grid

In this paper, we illustrate the effect of adding a hypothetical 100-MW doubly fed induction generator (DFIG) wind power plant to a weak transmission system. The effects of various wind plant load factors (100, 60 and 25% of nameplate rating) are investigated. System performance is compared to a 100-MW conventional synchronous generator interconnected at the same location. The conventional generator is installed some distance away. The simulations demonstrated that DFIG generators provide a good damping performance under these conditions. These results support the conclusion that modern wind power plants, equipped with power electronics and low-voltage ride-through capability, can be interconnected to weak power grids without reducing stability. To conduct the studies, we selected an area of the Western Electricity Coordinating Council power system that is electrically far from major generation centers and is weakly connected to the bulk transmission system. The area contains large motor loads. We observed the dynamic response of large motors in the vicinity, especially their ability to ride through fault events. The studies were conducted using positive sequence phasor time-domain analysis

The evolution of wind power integration studies: Past, present, and future

The rapid growth of wind power as a generation resource in the past decade has given many utilities and Regional Transmission Organizations (RTO) concerns due to its unconventional characteristics. Because of these concerns, many of these entities have initiated studies that evaluate the feasibility of large amounts of wind power onto their system and the operational impacts present. This paper will discuss some of the past major studies, mostly focusing on the United States, and the basic methodologies that were used during these studies. The paper will also review many of the different results and conclusions of the studies and discuss how they have helped the power industry as a whole. Lastly, the authors will attempt to share their ideas on some of the limitations of the current and past integration studies, and some insight on how these may be evolving in the future.

Output Power Correlation Between Adjacent Wind Power Plants

The National Renewable Energy Laboratory (NREL) started a project in 2000 to record long-term, high-frequency (1-Hz) wind power data from large commercial wind power plants in the Midwestern United States. Outputs from about 330 MW of installed wind generating capacity from wind power plants in Lake Benton, MN, and Storm Lake, Iowa, are being recorded. Analysis of the collected data shows that although very short-term wind power fluctuations are stochastic, the persistent nature of wind and the large number of turbines in a wind power plant tend to limit the magnitude of fluctuations and rate of change in wind power production. Analyses of power data confirms that spatial separation of turbines greatly reduces variations in their combined wind power output when compared to the output of a single wind power plant. Data show that high-frequency variations of wind power from two wind power plants 200 km apart are independent of each other, but low-frequency power changes can be highly correlated. This fact suggests that time-synchronized power data and meteorological data can aid in the development of statistical models for wind power forecasting.

Best Practices in Grid Integration of Variable Wind Power: Summary of Recent US Case Study Results and Mitigation Measures

This paper will summarize results from a number of utility wind integration case studies conducted recently in the US, and outline a number of mitigation measures based on insights from those studies.

Wind Energy and Power System Operations: A Survey of Current Research and Regulatory Actions

Energy imbalance provisions in open access transmission tariffs pose a formidable obstacle for commercial wind energy development in the U.S. To allow wind project development to proceed, some ISOs have adopted provisions reflecting the variable nature of wind energy resources.

A Study of a Wind Farm Power System

A wind power system differs from a conventional power system. In a conventional power plant, the operator can control the plant’s output. The output of a wind farm cannot be controlled because the output fluctuates with the wind. In this study, we investigated only the fixed-frequency induction generator, often used with wind turbines. We adopted the worst-case scenario and conducted a per-phase, per-turbine analysis. Our analysis showed a strong interaction among the wind farm, the utility grid, and the individual generator. In this paper, we investigate the power-system interaction resulting from power variations at wind farms using steady-state analysis. We use the characteristic of a real windsite on a known weak grid. We present different types of capacitor compensations and use phasor diagrams to illustrate the characteristics of these compensations. The purpose of our study is to provide wind farm developers with somc insights on wind farm power systems.Copyright

Characteristics of Variable Speed Wind Turbines Under Normal and Fault Conditions

Variable-speed wind turbines with full power processing capability are the new technology trend for large wind power plants. In this type of turbine, there is an interface between the generator and the utility grid. In this paper, we investigate the characteristics of a variable-speed wind turbine connected to a stiff grid or a weak grid, the role of reactive power compensation in optimizing the operation of the wind turbines, and the operation of a wind turbine under normal and fault conditions. Both steady state and dynamic analysis are presented.

Wind Integration [Guest Editorial]

Looking back two years to the last issue of IEEE Power and Energy Magazine devoted to utility wind integration issues, much has changed and much has stayed the same. In the middle of 2009, the United States was experiencing its best year ever in terms of wind plant installation, setting a new record of 10,000 MW installed. The installation rate took a nose dive in 2010, falling in half to 5,000 MW, in the midst of an economic recession, declining demand, and low natural gas prices. Projections for 2011 are somewhat better than 2010, but not as good as 2009.

It's in the air [Guest Editorial]

I it is a great pleasure for Brian Parsons of the National Renewable Energy Laboratory (NREL) and myself to once again serve as guest editors of IEEE Power & Energy Magazine. This special issue is dedicated to the integration of wind power plants into power system planning and operations. It has been truly phenomenal to watch the explosion of interest and information about this topic in the past fi ve years. We have gone from a situation in which wind energy was a boutique business that was not taken very seriously to one in which wind now accounts for the second-largest share of new generating capacity installed in the past year (just behind natural gas).

Output Power Correlation Between Nearby Wind Power Plants

The National Renewable Energy Laboratory (NREL) started a project in 2000 to record long-term, high-frequency (1-Hz) wind power output data from large commercial wind power plants. Outputs from about 330 MW of wind generating capacity from wind power plants in Buffalo Ridge, Minnesota, and Storm Lake, Iowa, are being recorded. Analysis of the collected data shows that although very short-term wind power fluctuations are stochastic, the persistent nature of wind and the large number of turbines in a wind power plant tend to limit the magnitudes and rates of changes in the levels of wind power. Analyses of power data confirm that spatial separation greatly reduces variations in the combined wind power output relative to output from a single wind power plant. Data show that high frequency variations of wind power from two wind power plants 200 km apart are independent of each other, but low frequency power changes can be highly correlated. This fact suggests that time-synchronized power data and meteorological data can aid in the development of statistical models for wind power forecasting.© 2003 ASME