05-12-2012, 12:23 PM
Optimal and Direct-Current Vector Control of Direct-Driven PMSG Wind Turbines
Optimal and Direct-Current.ppt (Size: 189.5 KB / Downloads: 33)
Abstract
A PMSG wind turbine with two back-to-back voltage source IGBT converters are considered more efficient
It has been widely adopted by wind power industry
The proposed approach based on a “Direct Current Vector Control (DCVC)”
The DCVC for control the machine side converter (MSC) and grid side converter (GSC)
This control strategy is developed to control of PMSG max power extraction, reactive power control and grid voltage support control
Introduction
In recent days renewable energy sources are rapidly growing.
A wind turbine manufacturers are developing a new megawatt scale wind turbines based on variable speed operation with pitch control using a PMSG
Compared to conventional vector control strategy DCVC has many advantages. Such as
Enhanced system stability,
reliability and
efficiency.
Advantages of PMSG
Gearless construction,
Elimination of a dc excitation system,
Fully controllability of the system for maximum wind power extraction and grid interface,
Therefore, the efficiency and reliability of the Voltage Source Converter(VSC) based PMSG wind turbine is assessed to be higher than that of DFIG wind turbine
PMSG Mechanical/Electrical systems
The control of PMSG system has three levels
Generator Level
MSC is used to achieve the max energy extraction from the wind,
GSC is used to maintains a constant dc-link voltage and adjust the reactive power abosorbed from the grid by the converter
Wind turbine level
Speed controller and power limiting controller
At low wind speeds, the controller gives a power or torque reference to the MSC based on the principle of maximum energy capture.
The power limiting controller increases or decreases the pitch angle of wind turbine blades to prevent the turbine from going over the rated power at high wind speeds.
Wind power plant level
The power production of the entire plant is determined based on the grid requirement.