Line-to-line short-circuit-based finite-element performance and parameter predictions of large hydrogenerators

Abstract

A two-dimensional (2-D), time-stepped finite-element (FE) method is used to model and successfully replicate saturated line-to-line and three-phase short-circuit test responses recorded on a 40-pole 13.75-MVA hydrogenerator at Hydro-Quebec's Rapides-des-Quinze generating station. Three levels of line-to-line and sudden three-phase short-circuit tests (0.13, 0.25, and 0.48 p.u.) are simulated numerically using the FE-based model. While symmetrical faults are only used for parameter determination, the computed line-to-line waveforms are thoroughly compared to real data, with special attention given to field current responses. According to IEEE Std.-115-1995, the -axis dynamic reactances and time-constants are computed from three-phase short-circuit tests while the negative-sequence reactance is derived from the line-to-line short-circuit test resulting in a rated armature current. The obtained simulated tests responses and parameter values, from both symmetrical and asymmetrical faults, support the effectiveness of the proposed FE-based model in incorporating the saturation phenomenon, large number of poles, and detailed damper representation to achieve an accurate dynamic performance assessment together with negative-sequence reactance and dynamic constants prediction. Index Terms-Performance and parameter predictions, synchronous machines, transient electromagnetic analysis.

Effect of Voltage Sag on the Transient Performance of Saturated Synchronous Motors

“…(dq and Vqd) due to this phenomenon [8,9] in (4) and (5). The d-and q-axis components of the total magnetizing ampere-turns are used in this case to obtain the dand q-axis saturation factors from the corresponding saturation characteristics.…”

“…In the analysis of the transient performance of synchronous motors during and after the sag, the accurate calculation of the stator and rotor currents, load angle and air-gap torque depends on the saturation conditions [7,8]. However, the effect of the saturation in the transient analysis of synchronous motors is commonly either ignored or improperly represented [4][5][6].…”

Simulation of a Large Power Brushless Synchronous Generator (BLSG) With a Rotating Rectifier by a Reluctance Network for Fault Analysis and Diagnosis

“…Nonlinear transient models using 2D finite elements coupled with an external armature electrical circuit can also be used to simulate certain short-circuit fault scenarios [6]- [7]. These models give good accuracy but require considerable computation time, as reported in [6].…”

“…These models give good accuracy but require considerable computation time, as reported in [6]. A complete study of multiple fault scenarios for bridge-rectified generators with a large number of phases and diodes is very difficult to carry out using finite element models.…”

Transient finite-element analysis and testing of a salient-pole synchronous generator with different damper winding design solutions

“…When the design of the machine follows usual practices, a fundamental help in facing these issues comes from designers' experience and heuristic methods, but as soon as the design deviates from the standard, relying on experience may become difficult if not misleading. In such circumstances, today's state-of-the-art computational techniques, which apply Finite Element Analysis (FEA) methods to the study of transient and three-dimensional problems, may constitute the more appropriate answer [7].…”