Analysis of armature winding open‐phase fault in multi‐phase annular brushless exciter at nuclear power plant

Abstract

The multi-phase annular brushless exciter (MPABE) of nuclear power plants has suffered numerous armature winding open-phase faults (AWOPF) in the field operation. In order to achieve reliable protection of the MPABE, its AWOPF is systematically studied through theoretical analysis, simulation calculation and model machine experiments. First, proceeding from the armature current waveform in normal operation and the influence of the AWOPF on it, the armature reaction magnetomotive force (MMF) is analysed deeply. Then, the theoretical analysis about the harmonic electromotive force (EMF) induced by armature reaction MMF on the field winding is presented, obtaining the harmonic characteristics of field current: the even-order field harmonic currents increase obviously under the AWOPF. Finally, correlate experiments and simulations were performed on a customized experimental prototype. The experimental and simulation results are consistent and verify the conclusion of the theoretical analysis, which can serve as a theoretical basis for the monitoring and diagnosis method of the AWOPF in the MPABE. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Detection of an Incipient Fault for Dual Three-Phase PMSMs Using a Modified Autoencoder

“…The introduction of a regular term can achieve this purpose. The Laplace regular term of the weight matrix is constructed according to the [30], which can be defined as (7) where K represents the number of weight matrices in the multi-layer AE, σ denotes the penalty factor, ∆ = D 1 ⊗I 2 + I 1 ⊗D 2 , I 1 and I 2 are the identity matrixes, D 1 and D 2 are the Laplace operator. The modified Neuman discretization operator is used to obtain D 1 and D 2 , which means a second-order difference calculation [30].…”

“…The differences denoted in (1), ( 6) and (7) are integrated together to get the objective function of the multi-domain AE, which is given by e = e AE + λ 1 e MMD+MCD + λ 2 2 e weight (8) where both λ 1 and λ 2 are regularization parameters. The purpose of introducing the regularization parameter is to improve the extraction ability of the common features.…”

“…For the model-based approach, the observer and parameter estimation are applied to the incipient fault detection [3]. For the signature-based approach, different signals including current [4], voltage [5], flux [6] and electromotive force [7] are used for intrusive and nonintrusive detection. To achieve the nonintrusive detection, a motor current signature analysis (MCSA) is the common approach for various types of motors [8], where the frequency analysis of the phase currents is performed to monitor the unusual harmonics caused by an interturn fault.…”

An efficient integrated model for diesel‐engine three stage brushless synchronous generator

“…� large-capacity turbo-generator sets [4] and ultra-large nuclear power plants [5]. � on-board power generation systems and starter-generators where reliability and safety are very important such as aircraft and marine vessels [6][7][8].…”

“…In brushless excitation mode, the brushes and slip rings are eliminated, resulting in no spark and brush wear which improve system reliability and eliminate frequent maintenance requirement [1–3]. Due to these features, brushless synchronous generators (BLSG), apart from their traditional role as power generation in power plants, are preferred in many applications including. large‐capacity turbo‐generator sets [4] and ultra‐large nuclear power plants [5]. on‐board power generation systems and starter‐generators where reliability and safety are very important such as aircraft and marine vessels [6–8].…”