Qualitative performance assessment of semiconductor switching device, converter and generator candidates for 10 MW offshore wind turbine generators

Abstract

This paper investigates the possibilities of viable power electronics converters, semiconductor switching devices and electric machines for 10 MW variable-speed wind turbine generators. The maximum rated power of existing wind turbine confi gurations is in the range of 6 MW. The proposed alternatives are compared against several technical and economical factors, and their advantages over the present wind turbines are highlighted. A comprehensive performance comparison of modern power semiconductor devices, their electrical characteristics and the key differentiators among them are presented. The power electronics converters considered include all commercially available multilevel voltage source and current source converters as well as the opportunities offered by power electronics building block-based design. The factors used for the comparison include the converter power range, capacitor voltage balancing, common mode voltage and current, electromagnetic interference emissions, fault ride-through capability, reliability, footprint, harmonic performance, effi ciency and losses, component count, risk of torsional vibration by the harmonics and inter-harmonics, complexity, ease of back-to-back operation and fi ltering requirements. For the electric machines, this study concentrates on high-temperature superconducting machines, multi-phase induction machines and permanent magnet synchronous machines. These machines are compared against existing wind generator technologies in terms of their power range, torque density, effi ciency, fault ride-through capability, reliability, footprint, harmonic performance, ease of fault detection, excitation control, noise and vibration signature, oscillation damping, gearbox requirement, cost and the size of the associated converter.Converter and generator candidate assessment for 10 MW wind turbines B. Badrzadeh 426This paper evaluates the viable and reliable alternatives for high-power wind turbines for very large wind farms. For the assessment, a rated power of 10 MW per turbine is assumed. The alternatives considered are already available in the marketplace (high-power converters and electric machines in this power range have been used in applications such as oil and gas, marine propulsion and utility grid for many years), or are being commercialized for the required power range. Options such as switched reluctance machines, resonant converters and matrix converters are not therefore considered as they are not available in the market for MW range applications.Modern power semiconductor devices including gate turn-off thyristors (GTOs), insulated gate bipolar transistors (IGBTs), insulated gate commutated thyristors (IGCTs), injection enhanced gate transistors (IEGTs), symmetrical gate commutated thyristors (SGCTs) and their electrical characteristics are discussed. A comprehensive performance comparison of these devices in terms of the device rating, switching frequency, gate driver circuit requirements, failure mode, cooling methods and device over-voltage and over-current pro...

Generator with modulated magnetic flux for wind turbines

“…The advantages over EESGs are: smaller rotor diameters, higher reliability due to elimination of different mechanical components, better thermal characteristics, and lower mass per kilowatt of output power [21−24]. The disadvantage is that PMSGs need more robust control strategies, in order to maintain transient stability and avoid the risk of wind turbine mechanical runaway during faulty conditions [21]. The PM generators are recognized as being the most efficient choice among the current generator designs on the market.…”

“…HTS windings can operate at a very high temperature and can be cooled with low cost and reliable off-the-shelf refrigerators [26,27]. Thus, HTS wires provide higher current densities (up to 200 A/mm 2 compared with about 5 A/mm 2 in EESGs [21], reducing the space required for the rotor field winding [21, 24−27]. The possibility of placing more turns of field winding in a small volume also allows for an increase of the air-gap flux density, consequently making it possible to increase the air-gap, resulting in weight reduction and less stress.…”

A review on the development of wind turbine generators across the world

“…This work categorizes generators based on the principles of operation. Figure 4 shows various types of electric machines, ranging from DC electric generators to new state-of-the-art high-temperature-superconducting (HTS) generators [10][11][12]. The main focus of this paper is on the AC poly-phase group, which is the main concept used in the wind power industry.…”

“…The rotor in a PMSG is replaced with PMs; the excitation is provided by PMs instead of the field winding, but the stator winding is the same as that of a three-phase EESG [28]. PMSGs have several advantages over EESGs, including smaller rotor diameters, higher reliability due to elimination of different mechanical components such as slip rings, better thermal characteristics, and lower mass per kilowatt output power [12,31,34,35]. Lower weight in PMSGs is achieved by such modifications as eliminating the gearbox, and providing a larger airgap that reduces flux linkage and results in a smaller generator size with respect to the wind turbine power rating [31].…”

“…Other advantages of DD PMSGs are discussed in the literature [23][24][25]28,[36][37][38]. High cost of PMs, manufacturing and assembling, and demagnetization of PMs at high temperatures are among main drawbacks of a PMSG [12,31,33,39,40]. In recent years, improvements in the PM performance and the cost reduction have made them more attractive than before.…”