Page 168 - Renewable Energy Devices and System with Simulations in MATLAB and ANSYS

Small Wind Energy Systems 155

TABLE 7.1
Electrical Criteria of a Wind Energy Generator

Electrical Criterion PMSG SEIG SCIG DFIG
Voltage regulation Voltage boost Poor Poor Medium
procedures
Speed regulation Total Total (10% > n s ) Total ±30%
Frequency regulation High Low Poor Low
Number of poles Typically, 24 4 4 4
Power converter Full scale Lower switching Lower switching Small PWM
frequency frequency
Losses in power Very high stress Small Small High
converter levels
Field losses None Medium Medium Medium
Brushes and slip rings None None None Necessary
Ride-through capability Not so complex Complex Complex Complex
Connectivity Medium Easy Easy Medium
Efficiency 91% 75% 89% 88%
Flexibility High High High High

Abbreviations: PMSG, permanent magnet SG; SEIG, self-excited IG; SCIG, squirrel cage IG; DFIG, doubly fed IG.

TABLE 7.2
Mechanical Criteria of a Wind Energy Generator

Criterion PMSG SEIG SCIG DFIG
Thermal dissipation Minimum losses Medium Medium Medium
Manufacturing Moderate Easy Easy Involving
requirements
Adaptability High High High High
Expertise for using Medium Low Low High
the generator
Pollution levels, Medium Low Minimum Low
environment impacts
Portability Medium High High Medium
Reliability High High High Top medium
Robustness High High High Medium
Service interruption Low Low Low Low
Knowledge and New Easy Easy Involving
technology needs
Turbine-generator Possibly direct Direct or with Direct or with Direct coupling
coupling gearbox gearbox
Power per weight and Toward light Low Low Medium
per volume