Permanent magnet synchronous generator design solution for large direct-drive wind turbines: Thermal behavior of the LC DD-PMSG

Abstract

Wind is one of the most compelling forms of indirect solar energy. Available now, the conversion of wind power into electricity is and will continue to be an important element of energy self-sufficiency planning. This paper is one in a series intended to report on the development of a new type of generator for wind energy; a compact, high-power, direct-drive permanent magnet synchronous generator (DD-PMSG) that uses direct liquid cooling (LC) of the stator windings to manage Joule heating losses. The main param-eters of the subject LC DD-PMSG are 8 MW, 3.3 kV, and 11 Hz. The stator winding is cooled directly by deionized water, which flows through the continuous hollow conductor of each stator tooth-coil winding. The design of the machine is to a large degree subordinate to the use of these solid-copper tooth-coils. Both steady-state and timedependent temperature distributions for LC DD-PMSG were examined with calculations based on a lumpedparameter thermal model, which makes it possible to account for uneven heat loss distribution in the stator conductors and the conductor cooling system. Transient calculations reveal the copper winding temperature distribution for an example duty cycle during variable-speed wind turbine operation. The cooling performance of the liquid cooled tooth-coil design was predicted via finite element analysis. An instrumented cooling loop featuring a pair of LC tooth-coils embedded in a lamination stack was built and laboratory tested to verify the analytical model. Predicted and measured results were in agreement, confirming the predicted satisfactory operation of the LC DD-PMSG cooling technology approach as a whole.

Optimization of Offshore Direct Drive Wind Turbine Generators With Consideration of Permanent Magnet Grade and Temperature

“…Grauers shows a method where the outer surface of the generator stator core is cooled by cooling channels using forced air [5]. Alexandrova et al manage the losses of the stator winding due to joule heating by internal direct liquid cooling [6]. Others have looked at different cooling methods and coolants [4], [7], [8].…”

Optimized distribution of a large number of power electronics components cooled by conjugate turbulent natural convection

“…Reliability issues in offshore devices (due to expansive maintenance operation) make these renewable power systems a new important application of thermal engineering (e.g. for cables [34] or for generators [35]). Power electronics play a major role in the development of renewable energy sources, for instance wind power, solar power, and marine power.…”

Conceptual Framework of Antecedents to Trends on Permanent Magnet Synchronous Generators for Wind Energy Conversion System

“…The calculations from lumped-parameter thermal model were utilized to study the steady-stated and time-dependent temperature distributions of LC DD-PMSG thereby resulting in the uneven heat loss distribution in the stator conductor as well as conductor cooling system. Using FEA, liquid-cooled tooth-coil design to analyze the cooling performance of the liquid was predicted [32]. In order to investigate the thermal behaviour of Axial Flux Synchronous Permanent-Magnet Machines (AFSPMMs) using a 3-D thermal-magnetic finiteelement analysis (FEA) that may provide a systematic approach to magno-thermal FEA, Fabrizio Marignetti, et al, (2008) presented a study on the same.…”