A Novel Multidimensional Frequency Band Energy Ratio Analysis Method for the Pressure Fluctuation of Francis Turbine

Wang, Weiyu; Liang, Xing; Yue, Xuhui; Dou, Jinzhou

doi:10.1155/2018/3494785

Cited by 4 publications

(3 citation statements)

References 20 publications

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“…The pressure fluctuation of the draft tube will have an impact on the vibration of unit components. At the upper frame, there are obvious lowfrequency components (1/3-1/5)f 1 (f 1 is the unit rotation frequency) superposition in the upper frame vibration waveform [27]. Therefore, fault are to the upper frame vibration waveform of the unit under normal conditions, and abnormal vibration caused by the draft tube vortex belt is simulated, which is marked as an analog fault.…”

Section: Verification Based On Actual Measurement Data Of Hydropower ...mentioning

confidence: 99%

Design of a progressive fault diagnosis system for hydropower units considering unknown faults

Chen,

Zheng,

Deng

et al. 2023

Meas. Sci. Technol.

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To address the misidentification problem of signals containing unknown faults for hydropower units, a progressive fault diagnosis system is designed. Firstly, in view of the non-stationary and nonlinear vibration signals of hydropower units, the method of complementary ensemble empirical mode decomposition is used to process the normal and fault vibration signal samples, and the intrinsic mode function (IMF) and residual components with different frequencies are obtained. Then the IMF energy moment is calculated and used as the feature vector. Furthermore, a classifier (IMF-K1) is constructed based on the feature vector samples of the normal vibration signals of hydropower units, fault symptom indicators, and K-means algorithm to determine whether the hydropower unit is faulty; a classifier (IMF-K2) is constructed based on the feature vector samples of the fault vibration signals of hydropower units, fault symptom indicators, and K-means algorithm to determine whether the hydropower unit has the known fault; a classifier (IMF-bidirectional long short-term memory neural network (BiLSTMNN)) is constructed to distinguish the fault type of hydropower units by combining the eigenvector samples of known fault vibration signals, fault symptom indicators, and BiLSTMNN. Finally, a progressive fault diagnosis system for hydropower units is constructed using IMF-K1, IMF-K2, and IMF-BiLSTMNN, and comparative experiments are designed using the sample data from the rotor test bench and actual hydropower unit. The results show that the designed progressive fault diagnosis system has greater effectiveness in mining signal features and high fault diagnosis accuracy.

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Section: Verification Based On Actual Measurement Data Of Hydropower ...mentioning

confidence: 99%

Design of a progressive fault diagnosis system for hydropower units considering unknown faults

Chen,

Zheng,

Deng

et al. 2023

Meas. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…At present, fault diagnosis mainly focuses on feature extraction and trend prediction of monitoring signals of units, and the characteristic quantity of monitoring signals, especially Energies 2023, 16, 5592 2 of 19 vibration signals, is extracted by the signal processing method to judge the operating state and fault type of units [1,2]. At present, most of the studies focus on single-point signal analysis, focusing on local diagnosis, lack of evaluation, and analysis of the whole condition of the unit.…”

Section: Introductionmentioning

confidence: 99%

Hydropower Unit State Evaluation Model Based on AHP and Gaussian Threshold Improved Fuzzy Comprehensive Evaluation

et al. 2023

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Because a single monitoring index cannot fully reflect the overall operating status of the hydropower unit, a comprehensive state evaluation model for hydropower units based on the analytic hierarchy process (AHP) and the Gaussian threshold improved fuzzy evaluation is proposed. First, the unit equipment was divided into a hierarchical system, and a three-tier structure system (target layer-project layer-index layer) of the unit was constructed, and the weight of each component in the system was determined by the comprehensive weighting method. Secondly, according to the characteristics of the normal distribution of the historical health data of the unit, the upper and lower limits of the index were determined based on the Gaussian threshold principle, the real-time monitoring index degradation degree was calculated according to the index limit, and the degradation degree was applied to the fuzzy evaluation model to obtain the fuzzy judgment matrix. The result of assessment was divided into four sections: good, qualified, vigilant, and abnormal. Finally, combined with the unit hierarchical structure system, the weighted calculation of the fuzzy judgment matrix of each indicator, the overall fuzzy judgment matrix of the upper-level indicators of the unit was obtained, and the operating status of the unit was judged according to the matrix. Taking a real power plant unit as an example, the model was verified, and compared with other evaluation methods, the effectiveness and advantages of the proposed method were verified. In addition, the method proposed in this paper effectively solved the problems of index weighting and index limit determination in the existing model of unit condition evaluation.

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“…Hydraulic power, as a kind of renewable, clean, and economical resource, has been well developed in China [1][2][3]. By the end of 2015, the combined installed hydropower station capacity reached 320.03 GW [4,5].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Modeling and Dynamic Analyses of the Hydro–Turbine Governing System in the Load Shedding Transient Regime

2018

Self Cite

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Load shedding processes are widespread in hydropower stations, which has great influence on the safe and stable operation of the hydro-turbine governing system. In order to study the dynamic characteristics of the hydro-turbine governing system during the load shedding process, a novel nonlinear mathematical model of the hydro-turbine governing system is established considering the hydro-turbine system, the generator system and the governor system. In particular, a novel nonlinear mathematical model of the six hydro-turbine transfer coefficients is presented based on the definitions and hydro-turbine internal characteristics. After that, from the viewpoint of nonlinear dynamics and the practical engineering, the dynamic characteristics of the hydro-turbine governing system are investigated utilizing bifurcation diagrams, time series, Poincare maps, power spectrums and phase planes. Some meaningful results are found. The advantages of the novel nonlinear mathematical model are illustrated and commented in detail in comparison with the previous model. Finally, these models and analysis results will provide some theoretical references for the operation of hydropower stations in the load shedding transient.Energies 2018, 11, 1244 2 of 17 to optimizing the control of the HTGS. Based on the polynomial robust H ∞ optimization method, Eker [16] presented a robust single-input multi-output design approach for governors for speed control of hydro-turbines. Khodabakhshian and Hooshmand [17] put forward a new robust proportionalintegral-derivative (PID) controller for automatic generation control of hydro-turbine power systems, which is designed mainly based on a maximum peak resonance specification. Ren et al. [18] proposed an improved cascade control strategy for hydro-turbine speed governors, which can effectively decrease fluctuations of the rotational speed under non-Gaussian disturbance conditions in practical hydropower plants. Chen et al. [19] focused on designing the fractional-order PID controller using a chaotic non-dominated sorting genetic algorithm II for the HTGS, which has a better performance than traditional integer PID controllers. Zhang et al.[20] created a brand new non-linear predictive control method using the Takagi-Sugeno (T-S) fuzzy method and the generalized predictive control, which can govern a non-linear system more effectively. Chen et al.[21] established a new nonlinear mathematical model of the HTGS with a surge tank, and then, the nonlinear dynamical behaviors of the system in small fluctuation process were studied in detail. Guo et al. [22] studied the stability of the HTGS of the hydropower station with sloping ceiling tailrace tunnel utilizing the Hopf bifurcation theory, and also got the algebraic criterion of the occurrence of Hopf bifurcation. Xu et al. [23] built the Hamiltonian mathematical model of the multi-hydro-turbine governing system with a sharing common penstock under the excitation of stochastic and shock load, and then, discussed the stability of the system by comparing ...

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A Novel Multidimensional Frequency Band Energy Ratio Analysis Method for the Pressure Fluctuation of Francis Turbine

Cited by 4 publications

References 20 publications

Design of a progressive fault diagnosis system for hydropower units considering unknown faults

Design of a progressive fault diagnosis system for hydropower units considering unknown faults

Hydropower Unit State Evaluation Model Based on AHP and Gaussian Threshold Improved Fuzzy Comprehensive Evaluation

Nonlinear Modeling and Dynamic Analyses of the Hydro–Turbine Governing System in the Load Shedding Transient Regime

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