In recent years, an increasing popularity of deep learning model for intelligent condition monitoring and diagnosis as well as prognostics used for mechanical systems and structures has been observed. In the previous ...
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Integrated Energy system (IES), which plays a vital role in the development of Energy Internet (EI), can improve the efficiency of energy utilization and integration of renewable energy. However, the coupling between ...
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Body: By applying electromagnetic diffusion equation, skin effect in electrical steel sheets in the condition of alternating excitation is analyzed based on Maxwell electromagnetic field theory. Due to skin effect is ...
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Body: By applying electromagnetic diffusion equation, skin effect in electrical steel sheets in the condition of alternating excitation is analyzed based on Maxwell electromagnetic field theory. Due to skin effect is more significant mainly at high frequency, non-dimensionalized treatment for the diffusion equation is produced and eddy current loss is calculated by considering or not skin effect, respectively. Meanwhile, broadband magnetic losses and separation of typical electrical steel are obtained by using a 3-D magnetic properties testing system to bring to light the emergence of skin effect under rotational excitation. The simplification of magnetic constitutive equation is proposed and introduced into the diffusion equation, which is solved by employing finite elements coupled to Fredholm's equation. An approximate expression for the rotational eddy current loss component with skin effect is eventually written. The simulations show that due to the influence of skin effect, non-uniform distribution of induction flux density within electrical steel sheets will become more and more significant, the fl ux density and fi eld intensity nearby the surface are larger than that in the centre of the sheets [1, 2]. And with increasing of alternating excitation frequency, the inhomogeneity of induction flux density will be extended and growing more inhomogeneous, due to the smaller skin depth and a small increase of anomalous loss in the total core losses, as shown in Fig. 1.2. Therefore, alternating eddy current loss P as functions of the peak mean alternating flux density B mamean and the alternating excitation frequency f a can be deduced as follows: limv→∞P ae (B ma_mean f a )=[2ω a (B ma_mean ) 2 /3ρμν 2 =(σπ 2 d 2 /3ρ)(f a ) 2 (B ma_mean ) (no skin effect)[W/kg] (1) limν→0 P ae (B ma_mean f a )=[4ω a (B ma_mean ) 2 /ρμν=(4σ 1/2 π 3/2 d/ρμ 1/2 )(f a ) 3/2 (Bma_mean) 2 (considering significant skin effect) [W/kg] (2) where, ω a is the angular frequency; v = 2δ
On the basis of damping principle of vibration, the domain wall processes is investigated and modeled at low-to-medium frequencies in electrical steel sheets. Due to the energy dissipation chiefly descends from a micr...
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On the basis of damping principle of vibration, the domain wall processes is investigated and modeled at low-to-medium frequencies in electrical steel sheets. Due to the energy dissipation chiefly descends from a micro-vortex current caused by domain wall motion, the coupled Landau-Lifshitz-Gilbert (LLG) and Maxwell electromagnetic diffusion equations are thus considered to describe the high-frequency characteristics. The overall core losses are eventually deduced in terms of separate contributions by domain wall processes and classical eddy current. Moreover, the calculation model can be extended to rotational excitation pattern. Hence, taking the typical electrical steel sheets as example, the novel core losses calculation model is analysed and compared with the total alternating core losses supplied by electrical steel sheets manufacturers and the 3-D rotating experimental core losses of sheets specimens which are carried out by using a 3-D magnetic properties testing system.
Body: power transformers and reactors are important devices in power transmission systems. But their cores and windings could produce vibration and acoustic noise by magnetostrictive effect, Maxwell electromagnetic st...
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Body: power transformers and reactors are important devices in power transmission systems. But their cores and windings could produce vibration and acoustic noise by magnetostrictive effect, Maxwell electromagnetic stress and Lorentz force. Noise has become a bad environmental pollution source in some situations, and its vibration and noise reduction has become an urgent problem need to be solved. The shapes, materials, magnetostriction and joints forms of iron cores, the limitations of test, modeling, and experimental measurement of vibration and noise characteristic, are all the difficult reasons to analyze the vibration and acoustic noise of transformers and reactors. 1. The magnetostrictive modeling can be divided into two steps based on the magnetic field force and materials deformation, so the magnetic field force will be fed into the structural finite element with Maxwell electromagnetic force produced on the interface between the iron core and the air to calculate the deformation of the magnetic materials and to make the model more general and consistent. In order to fully verify the correctness of the model in the magnetostrictive analysis, and to ensure the simplicity of test and avoid unnecessary interference factors, the most simple magnetostriction tests will be carried out by using a single closed circle or rectangular electrical steel sheet, as shown in Fig. 1(a). The tests will measure the relationship between magnetostriction and magnetic field of different magnetic materials, different saturations, different sizes and different shapes. 2. The joint is a necessary form for the stacking of large transformer iron cores, and the main joint form is the step jiont at present. The introduction of the joints causes the magnetic force lines to flow through the different laminations and to make the local magnetic field complicated. From simple to complex process is adopted in this paper, and the verification is gradually complicated. Based on the study of a
The control schemes of distributed energy resources (DERs) in active distribution networks (ADNs) are largely influenced by uncertainties. The uncertainties of DERs are complicated, containing spatial and temporal cor...
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With the rapid deelopment of demand-side response and active distribution network, the new method to power and energy balance is becoming more and more important. In this paper, the architecture of power and energy ba...
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With the rapid deelopment of demand-side response and active distribution network, the new method to power and energy balance is becoming more and more important. In this paper, the architecture of power and energy balance in active distribution network is proposed, which consists of three parts: load and generation forecasting, power and energy balance. Moreover, capacity-load ratio guidance is modified combined with the peak shaving potential and trusted capacity. Besides, the energy balance method considering the operation-control of distributed energy is proposed. Finally, through numerical analysis, the feasibility and practicability of the model are verified.
The rapid growing scale of electric vehicles (EV) has brought benefit and impact on urban traffic network and the electric powersystem simultaneously by integrating these two systems together into a Cyber-Physical-So...
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The rapid growing scale of electric vehicles (EV) has brought benefit and impact on urban traffic network and the electric powersystem simultaneously by integrating these two systems together into a Cyber-Physical-Social system (CPSS) in energy. This paper presents a coordinated analysis method of the urban integrated energy-traffic network based on real-world GPS data from vehicles in Shenyang and Shenzhen, China. Case study shows that the integrated system will be affecting each other through the coupling interactions of EVs.
With the technological advancement in the fields of advanced metering infrastructure (AMI), a massive amount of customers’ electricity consumption data is collected. Meanwhile, the energy providers need to make infor...
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With the technological advancement in the fields of advanced metering infrastructure (AMI), a massive amount of customers’ electricity consumption data is collected. Meanwhile, the energy providers need to make informed decisions based on power consumption strategy of demand side to reduce overall operational cost. So how to generate demand side load data based on historical energy consumption data or customer attribute is a pressing issue. In this paper, we propose a data-driven approach to generate new power consumption data based on intrinsic property of load pattern learnt from demand side using conditional generative adversarial networks (cGANs), which is based on two interconnected deep neural networks known as generator and discriminator. By using several representative labels from the responded surveys and the load data from demand side to train the models, the generator is able to generate realistic power consumption data by given labels which can be used for energy management and scheduling, the discriminator is capable of detecting abnormal power consumption and system error from the smart meter data.
In order to improve the energy efficiency and compact structure, the dual-rotor structure including lowpressure rotor and high-pressure rotor has been widely used in aero-engine. Misalignment is one of the most common...
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In order to improve the energy efficiency and compact structure, the dual-rotor structure including lowpressure rotor and high-pressure rotor has been widely used in aero-engine. Misalignment is one of the most common faults in dual-rotor system, which will causes malfunctions. It is a significant task for rotor dynamics personnel to monitor and defect faults in dual-rotor system. In the paper, the dual-rotor vibration signals are applied to solve the fault identification problem by utilizing time frequency techniques. Numerical simulations are carried out through finite element analysis of dual-rotor system with misalignment fault. Two signal processing tools namely Short Time Fourier Transform (STFT) and Continuous Wavelet Transform are used to detect the misalignment fault and compared to evaluate their diagnosis performance. The effect of addition of Signal to Noise (SNR) on three frequency techniques is presented. Experiments are carried out to obtain the vibration data of dual-rotor test rig and the results from the work show that the technique can be used for the monitoring of misalignment, which will have applications in the condition monitoring and maintenance of various types of rotating machinery.
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