In order to detect the abnormal temperature of large oil-Immersed power transformer earlier, this paper presents a new prediction-model of surface-temperature for the transformer to predict the normal surf ace-tempera...
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ISBN:
(纸本)7506274078
In order to detect the abnormal temperature of large oil-Immersed power transformer earlier, this paper presents a new prediction-model of surface-temperature for the transformer to predict the normal surf ace-temperature. And to compare the difference between the predicted value and the measured value can judge If the condition of the transformer Is fit to operate. The model parameters are estimated from the field data by using the Partial-Least-Square method, which overcomes the instability of results estimated by using the traditional Least-Square method. Furthermore, the appropriate amount of data for the parameter estimation was decided according to the principle of Heat Transfer and the characteristics of the predicted deviation, such as mean, variance and normal distribution. The prediction model is verified from the accuracy of results predicted with one year of field data.
Two axially-laminated Glued Axially-Laminated Synchronous Reluctance Permanent Magnetic (SR-PM) motors are designed and tested. Compared to general Axially-Laminated Synchronous Reluctance (SR) motors, the steel brack...
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To research the influence of multi-phase winding to generators and calculate the losses in solid rotors, the stator mint of a 12-phase asynchronous generator have been well analyzed and finite element method by ANSYS ...
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ISBN:
(纸本)7506274078
To research the influence of multi-phase winding to generators and calculate the losses in solid rotors, the stator mint of a 12-phase asynchronous generator have been well analyzed and finite element method by ANSYS software has been applied to get the accurate losses in the rotor through both harmonic and transient 2-D analysis. The relationship between stator harmonic current and stator harmonic mint has been deduced and proved through ANSYS software to some extent, and rotor losses produced by both stator fundamental current and stator total current have also been obtained and compared. The results show that 12-phase stator winding with appropriate short pitch can effectively eliminate or reduce many mmf produced by stator fundamental and harmonic current and rotor losses are mainly produced by stator fundamental current.
Computer control and monitoring system (CCMS) is quite important for high power converters (HPCs) operation. This paper presents a novel CCMS, which integrates a database management system (DBMS) into the monitoring s...
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ISBN:
(纸本)7506274078
Computer control and monitoring system (CCMS) is quite important for high power converters (HPCs) operation. This paper presents a novel CCMS, which integrates a database management system (DBMS) into the monitoring software to get the beneficial features such as simple configuration and compact structure. In its communication system, an advanced optical fiber communication (OFC) technology is applied and priority-based communications is proposed to improve the reliability and the real time of the communications. Furthermore, a friendly standard Windows human-machine interface (HMI) is provided. The reliability and performance of the system are verified by system tests and practical operations.
In view of the impossibility of current measurement in actual grounding plane in power electronic equipment, an equivalent circuit model is set up in this paper using the partial element equivalent circuit (PEEC) meth...
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ISBN:
(纸本)7506274078
In view of the impossibility of current measurement in actual grounding plane in power electronic equipment, an equivalent circuit model is set up in this paper using the partial element equivalent circuit (PEEC) method to simulate and calculate current distribution in grounding plane. The inductance parameters calculated are fairly coincident with experiment results, and some conclusions of current distribution are summarized. It is shown that the equivalent circuit model using PEEC method presented in this paper is a feasible and promising way to model and calculate current distribution in grounding plane.
This paper presents an accurate flux observer used in distributed multi-processor (DMP) adjustable speed drive systems. The stator flux linkage is estimated with a full-order observer, while the rotor speed is identif...
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ISBN:
(纸本)7506274078
This paper presents an accurate flux observer used in distributed multi-processor (DMP) adjustable speed drive systems. The stator flux linkage is estimated with a full-order observer, while the rotor speed is identified by using Lyapunov theorem. In order to improve the system performance in a wide speed range, the stator resistance is estimated simultaneously. In this paper, the structure of the DMP system, the principle of the full-order observer and the method for identifying the rotor speed and state resistance are all described in details. Relevant simulation results based on MATLAB/SIMULINK are given to prove the performance of the method. Experiments of a real system also verify the feasibility of this scheme.
Recursive least-squares temporal difference algorithm (RLS-TD) is deduced, which can use data more efficiently with fast convergence and less computational burden. Reinforcement learning based on recursive least-squar...
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In terms of the characteristic of instantaneous magnetizing inductance reflecting the saturation stage in transformer, an improved method is proposed to distinguish between the magnetizing inrush current and short-cir...
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In terms of the characteristic of instantaneous magnetizing inductance reflecting the saturation stage in transformer, an improved method is proposed to distinguish between the magnetizing inrush current and short-circuit fault based on the ratio of average equivalent instantaneous inductances between the non-saturation and the saturation zone, which are divided according to a threshold of differential current. During the inrush, the value of equivalent instantaneous inductance varies severely from small to large as the transformer entering into the saturation and withdrawing from it, so the ratio of average equivalent instantaneous inductances between the non-saturation and the saturation zone is very large in one cycle. However, for the short-circuit fault in transformer, the equivalent instantaneous inductance is very small, and keeps little variation, so the ratio is approximately equal to one. The principle and setting of this method is simple and easy, and its identification time is short. The experimental results verify that the method is correct and effective
To supply overall protection for large-sized turbo-generator, a new approach about leading-out mode of neutral points and disposition of protection schemes is firstly presented in this paper. To check up the sensitivi...
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To supply overall protection for large-sized turbo-generator, a new approach about leading-out mode of neutral points and disposition of protection schemes is firstly presented in this paper. To check up the sensitivity of the new protection scheme, two turbo-generators with 300 MW are simulated using the multi-loop method. simulation results indicate the performance of the new protection scheme is much better than that of the traditional protection. Without adding hardware investment, the new leading-out mode is agreed by electrical machine designers.
In order to detect the abnormal temperature of large oil-immersed power transformer earlier, this paper presents a new prediction-model of surface-temperature for the transformer to predict the normal surface-temperat...
详细信息
In order to detect the abnormal temperature of large oil-immersed power transformer earlier, this paper presents a new prediction-model of surface-temperature for the transformer to predict the normal surface-temperature. And to compare the difference between the predicted value and the measured value can judge if the condition of the transformer is fit to operate. The model parameters are estimated from the field data by using the partial-least-square method, which overcomes the instability of results estimated by using the traditional least-square method. Furthermore, the appropriate amount of data for the parameter estimation was decided according to the principle of heat transfer and the characteristics of the predicted deviation, such as mean, variance and normal distribution. The prediction model is verified from the accuracy of results predicted with one year of field data.
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