Cooling Airflow, Losses, and Temperatures in Large Air-Cooled Synchronous Machines

Abstract

At steady-state operation, power losses cause a heating of rotating electrical machines. In air-cooled machines, these losses are evacuated by a forced cooling airflow through the active parts. When designing and optimizing such a machine, the design engineer must be able to get a full picture of the power losses, the cooling airflow, and the temperatures inside the active parts (e.g., core laminations, windings) and the periphery (e.g., winding overhangs). The aim of the designer is to fulfill the customer's requirements regarding the guaranteed temperatures. This paper presents a computation method, where the power loss, airflow, and temperature calculations for the world's largest air-cooled hydrogenerators are coupled in an iterative process. The new contribution of this paper is a calculation software developed by the authors. It includes a state-of-the-art loss computation, an automated airflow network, and a set of linked thermal networks. These computations result in a complete overview of the temperature gradients and allow fine tuning of the cooling airflow and, consequently, optimization of ventilation losses.

A hybrid analytical-numerical approach for the analysis of salient-pole synchronous generators with a symmetrical damper cage

“…In fact, different configurations of this additional rotor winding have been investigated in [9], where a sensitivity analysis was carried out to understand its behaviour under steady state and transient conditions. Finally, particular focus has been recently given to the impact that this winding has on the quality of the output voltage waveform [10]. In [4], an unconventionally displaced damper winding has been proposed for such purposes, while trying to minimise the ohmic losses associated with it.…”

Damper cage loss reduction and no-load voltage THD improvements in salient-pole synchronous generators

“…In particular, "complete" and "incomplete" end connections are investigated in [12], [13] and [14], where the most important point to come out was predicting generator performance for various damper cage design alternatives. In [15] and [16], it was shown how FE analysis can be successfully used to achieve significant improvement in terms of the no-load voltage waveform. In this paper, a particular 4 MVA SG is analysed and investigated using FE analysis.…”

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

“…However, when the same case is considered in an air-cooled machine, the power losses are displaced by a forced cooling airflow between the active parts. The power losses, the cooling airflow, the temperatures inside the active parts (e.g., core laminations, windings) and the periphery (e.g., winding overhangs) should be considered while designing and optimizing such machine [57]. In order to manage the heating losses, Yulia Alexandrova,et al, (2014) presented a prospective compact, high-power, direct-drive permanent magnet synchronous generator (DD-PMSG) that uses direct liquid cooling (LC) of the stator windings where the main parameters of LC DD-PMSG being 8 MW, 3.3 kV, and 11 Hz.…”

“…As cooling is done by a separate engine, bearing friction and excitation system losses have not been considered. The loss of components that are considered are described in detail [57].…”