Detailed off-line parameter identification of synchronous generator based on frequency response tests

This work presents a general methodology, based on standstill frequency response tests. Once the circuit topology is chosen, it allows a systematic calculation of the circuit parameters for a salient pole synchronous generator. The order of the circuit considered can be whatever, even a customized circuit topology, since the methodology does not rely on a specific formulation. The transfer function coefficients are expressed as a function of the circuit parameters by using the symbolic Matlab toolbox. From tests, the coefficients of the transfer function are fitted in both axes. Then the coefficients have to match with the symbolic transfer function previously obtained in order to calculate the circuit parameters. If the dynamic behavior obtained with the fitted parameters is not accurate enough, the circuit order is increased until attaining an accurate solution. This methodology results in a useful educational tool for machine characterization. Nowadays many methods are found in the technical literature to calculate such parameters, although most of them computationally demanding.Peer ReviewedPostprint (published version

Real-Time Detection of Incipient Inter-Turn Short Circuit and Sensor Faults in Permanent Magnet Synchronous Motor Drives Based on Generalized Likelihood Ratio Test and Structural Analysis

This paper presents a robust model-based technique to detect multiple faults in permanent magnet synchronous motors (PMSMs), namely inter-turn short circuit (ITSC) and encoder faults. The proposed model is based on a structural analysis, which uses the dynamic mathematical model of a PMSM in an abc frame to evaluate the system’s structural model in matrix form. The just-determined and over-determined parts of the system are separated by a Dulmage–Mendelsohn decomposition tool. Subsequently, the analytical redundant relations obtained using the over-determined part of the system are used to form smaller redundant testable sub-models based on the number of defined fault terms. Furthermore, four structured residuals are designed based on the acquired redundant sub-models to detect measurement faults in the encoder and ITSC faults, which are applied in different levels of each phase winding. The effectiveness of the proposed detection method is validated by an in-house test setup of an inverter-fed PMSM, where ITSC and encoder faults are applied to the system in different time intervals using controllable relays. Finally, a statistical detector, namely a generalized likelihood ratio test algorithm, is implemented in the decision-making diagnostic system resulting in the ability to detect ITSC faults as small as one single short-circuited turn out of 102, i.e., when less than 1% of the PMSM phase winding is short-circuited.publishedVersio

Global identification of electrical and mechanical parameters in PMSM drive based on dynamic self-learning PSO

A global parameter estimation method for a PMSM drive system is proposed, where the electrical parameters, mechanical parameters and voltage-source-inverter (VSI) nonlinearity are regarded as a whole and parameter estimation is formulated as a single parameter optimization model. A dynamic learning estimator is proposed for tracking the electrical parameters, mechanical parameters and VSI of PMSM drive by using dynamic self learning particle swarm optimization (DSLPSO). In DSLPSO, a novel movement modification equation with dynamic exemplar learning strategy is designed to ensure its diversity and achieve a reasonable tradeoff between the exploitation and exploration during the search process. Moreover, a nonlinear multi-scale based interactive learning operator is introduced for accelerating the convergence speed of the Pbest particles; meanwhile a dynamic opposition-based learning (OBL) strategy is designed to facilitate the gBest particle to explore a potentially better region. The proposed algorithm is applied to parameter estimation for a PMSM drive system. The results show that the proposed method has better performance in tracking the variation of electrical parameters, and estimating the immeasurable mechanical parameters and the VSI disturbance voltage simultaneously

Diagnóstico da Ocorrência de Curtos-Circuitos entre Espiras nos Enrolamentos Estatóricos de Máquinas Síncronas de Relutância

A Máquina Síncrona de Relutância (SynRM) atraiu recentemente muito interesse devido à estrutura do seu rotor. A ausência de ímanes permanentes e de gaiolas/enrolamentos no rotor, bem como o baixo custo de fabricação e melhor desempenho, são as principais vantagens perante a sua concorrência, os motores síncronos de ímanes permanentes (PMSM) e motores de indução (IM). Deste modo, a ocorrência de curtos-circuitos entre espiras é uma das avarias mais perigosas em máquinas elétricas e, se estas não forem detetadas numa fase inicial de desenvolvimento, podem resultar em consequências graves, tanto em termos de segurança como em custos de reparação. Desta forma, este estudo foca-se sobre a problemática do diagnóstico da ocorrência de tais avarias, em SynRM. Neste trabalho, apresenta-se uma abordagem online eficaz para o diagnóstico de avarias de curto-circuito entre espiras, que se baseia no cálculo e monitorização de fatores específicos de severidade, baseados na transformada de Fortescue e definidos como a relação das componentes positivas e negativas da tensão e impedância. Esta abordagem é implementada num ambiente LabVIEW com o método Short Time Least Square Prony’s (STLSP). Isto não requer a determinação de parâmetros do motor e envolve apenas a utilização de sensores de tensão. Por fim, foram realizados vários testes num SynRM, para várias condições de funcionamento (saudáveis e defeituosas). Os resultados obtidos confirmam a eficácia da técnica proposta para o diagnóstico de avarias de curto-circuito entre espiras, com elevada fiabilidade, rapidez e precisão.The Synchronous Reluctance Machine (SynRM) has recently attracted much interest due to its rotor structure. The absence of permanent magnets and cage/winding in the rotor, as well as low manufacturing costs and improved performance, are the main advantages over its competitors, the Permanent Magnet Synchronous Machines (PMSM) and Induction Machines (IM). Therefore, the occurrence of inter-turn short-circuits is one of the most dangerous faults in electrical machines and if they are not detected at an early stage of development, they can result in serious consequences, both in terms of safety and repair costs. In this way, this study focuses on the problem of diagnosing the occurrence of such malfunctions in SynRM. In this work, an effective online approach is presented for the diagnosis of inter-turn short-circuits faults, which is based on the calculation and monitoring of specific severity factors, based on Fortescue transformation, and defined as the ratio between the positive, negative voltage and positive and negative impedance components. This approach is implemented in a LabVIEW environment with the Short Time Least Square Prony's (STLSP) method. This does not require the determination of motor parameters and only involves the use of voltage sensors. Finally, several tests were performed on a SynRM, for various operating conditions (healthy and faulty). The results obtained confirm the effectiveness of the proposed technique for diagnosing inter-turn short-circuit faults with high reliability, rapidity, and accuracy

Mise en place d'une méthodologie de modélisation en vue du diagnostic des défauts électriques des alternateurs

Devant la forte demande mondiale en énergie électrique, les alternateurs à diodes tournantes constituent une solution largement répandue dans les installations de génération d’électricité de fortes puissances (hydraulique, fossile et éolien) ainsi que dans les applications îlotées sous forme de groupes électrogènes ou de petits alternateurs intégrés dans les systèmes embarqués. La renommée de ce type d’alternateur s’est construite sur leurs robustes constitutions mécanique et électrique et sur leur parfaite adaptabilité au type de charge alimentée. Néanmoins, l’utilisation de ces machines dans des conditions de fonctionnement très contraignantes, que cela soit à cause des fortes puissances demandées par les applications industrielles ou des contraintes environnementales dans lesquelles travaillent les alternateurs isolés, engendre une recrudescence de défauts, principalement de types électriques, à l’intérieur du système. L’apparition de ces défaillances est extrêmement délétère pour des applications à haut niveau de service et dont un arrêt intempestif peut engendrer des coûts de maintenance et d’immobilisation très élevés pour les opérateurs. Devant la nécessité de planifier de façon optimisée les opérations de maintenance à effectuer sur les alternateurs, il est possible de mettre en place des stratégies de diagnostic qui surveillent l’apparition des principales défaillances susceptibles de toucher ce type de machine. Bien que les modifications imprévisibles du point de fonctionnement liées à la charge compliquent la tâche, il est envisageable de mettre en lumière la présence de défauts de court-circuit dans les bobinages ainsi que des défaillances de diodes dans le pont redresseur triphasé en étudiant les modifications des formes d’ondes des signaux électriques générés. Ce travail est décrit dans la présente thèse. Face au manque d’antécédents sur le sujet, une grande partie des recherches s’est focalisée sur la conception et la mise en place d’un modèle numérique d’alternateur à diodes tournantes représentatif des formes d’ondes réelles en régimes sain et défaillant, tache non triviale étant donné le caractère saillant des pôles de l’alternateur. Pour répondre à ces attentes, un processus original de co-simulation a été mis en place présentant une identification des inductances de l’alternateur sous Flux2D et une estimation numérique des équations différentielles du système sous Matlab. Cette modélisation fiable a par la suite permis une sélection d’indicateurs de diagnostic par analyse fréquentielle des signaux électriques qui sont capables, sans ajout de capteurs supplémentaires, d’informer l’utilisateur sur la présence de défauts à l’intérieur du système. Afin de s’assurer une bonne compréhension des phénomènes, un grand soin a été apporté à la justification théorique des modifications spectrales introduites par les défauts dans les signaux électriques. Une importante campagne d’essais expérimentaux a permis la validation des modèles sain et défaillant grâce à la réalisation, par la société Nidec Leroy- Somer, d’un alternateur capable de simuler des défauts de court-circuit inter-spires stator. Ces essais ont mis au jour la possibilité de détecter les défauts dans de nombreuses configurations de court-circuit, mais également la difficulté de les prévoir de façon anticipée, ouvrant par là même de nombreuses perspectives de recherche