Prediction of disruptions caused by locked modes using the Back-Propagation (BP) neural network is completed on J-TEXT tokamak. The network, which is based on the BP neural network, uses Mirnov coils and locked mode...
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Prediction of disruptions caused by locked modes using the Back-Propagation (BP) neural network is completed on J-TEXT tokamak. The network, which is based on the BP neural network, uses Mirnov coils and locked mode coils signals as input data, and outputs a signal including information of prediction of locked mode. The rate of successful prediction of locked modes is more than 90%. For intrinsic locked mode disruptions, the network can give a prewarning signal about 1 ms ahead of the locking-time. For the disruption caused by resonant magnetic perturbation (RMPs) locked modes, the network can give a prewarning signal about 10 ms ahead of the locking-time.
By using clutch for replacing rigid connection with a flexible one between hub and wheel-motor, a novel solution for in-wheel drive is proposed with the possibilities of `no-load starting and variable-idle clutching...
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ISBN:
(纸本)9781479951635
By using clutch for replacing rigid connection with a flexible one between hub and wheel-motor, a novel solution for in-wheel drive is proposed with the possibilities of `no-load starting and variable-idle clutching' together in this paper. It is then important to choose suitable idling speed of wheel motor for assuring drive comfort from a standing start in direct-drive electric vehicle. Based on the actual load torque, the control strategy of optimal idling speed is discussed in the aim of enhancing drive comfort and reducing electromagnetic impulsion.
Design of wheel motors must conform to the diameter restriction due to cage of a wheel rim and allow the achievement of high torque density. In addition, these motors should be rugged and insensitive to vibration. The...
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ISBN:
(纸本)9781479951635
Design of wheel motors must conform to the diameter restriction due to cage of a wheel rim and allow the achievement of high torque density. In addition, these motors should be rugged and insensitive to vibration. Therefore, an axial flux switched motor (AFSRM) machine with double stator and one rotor structure is investigated. In general, AFSRM have simple construction; however, one of the major problems is torque ripple which will cause speed fluctuation and acoustic noise. View of this, the skewed stator segments by a specific degree respectively to the rotor with asymmetric inductance property is applied to reduce the torque drop in the phase commutation area. The proposed method is analyzed by magnetic equivalent circuit approach (MECA) and finite element analysis (FEA) method. Through the parameter study, torque ripple reduction in proposed machine is significant in comparison with the one of conventional non-skewed stator machine.
In this paper, the d- and q-axis synchronous reactances of homopolar inductor alternator (HIA) are calculated. First, an approximate 2D model of HIA is developed and its relative air-gap permeance function is describe...
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In this paper, the d- and q-axis synchronous reactances of homopolar inductor alternator (HIA) are calculated. First, an approximate 2D model of HIA is developed and its relative air-gap permeance function is described. The harmonic amplitudes of the per-unit quantity of relative air-gap permeance function are determined by 2D finite element analysis (FEA). Then, the analytical expressions for the synchronous reactances in the direct-axis (d-axis) and quadrature-axis (q-axis) are derived from magnetomotive force (MMF)-relative air-gap permeance function theory, including armature reaction reactance and armature leakage reactance. Finally, theoretical results are compared with the simulation and experimental results.
This paper proposes a novel control structure for scalar sensorless V/f controlled permanent magnetic synchronous motor (PMSM) drives with two feedback corrections in the new created d v q v reference frame: i) a spe...
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ISBN:
(纸本)9781479951635
This paper proposes a novel control structure for scalar sensorless V/f controlled permanent magnetic synchronous motor (PMSM) drives with two feedback corrections in the new created d v q v reference frame: i) a speed stabilizing correction using input active power variation to moderate the stator applied frequency to ensure the stable operation, ii) a voltage amplitude correction employing the PI regulation of q v -axis current, that is the reactive current component, eventually realizes cosφ =1. The addition of PI regulator which also influences the stability of system is explored. Moreover, based on a basic V/f control, the scheme can greatly simplify the calculation and enhance insensitivity to the motor parameters. The proposed solution is simple, non-oscillatory and of good robustness. The simulation and experiments are carried out to prove the performance and validity.
Aiming at the simulation for the prime mover supplied by thyristor, the principle and the fundamental methods to dynamically simulate the self-balancing characteristics of a turbine are studied in this paper. A new sc...
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Aiming at the simulation for the prime mover supplied by thyristor, the principle and the fundamental methods to dynamically simulate the self-balancing characteristics of a turbine are studied in this paper. A new scheme is presented to simulate the characteristics of the prime mover when the generator simulator operates in various conditions. Nonlinear control components are adopted to solve long-existing problem on the simulation of the prime mover. Test results verify that the performance of the proposed scheme has its superiority.
There are mainly two existing loop gain measurement methods, which are the modulating signal perturbation method (MSPM) and the pulse-width signal perturbation method (PSPM). This paper points out that there are diffe...
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ISBN:
(纸本)9781479957774
There are mainly two existing loop gain measurement methods, which are the modulating signal perturbation method (MSPM) and the pulse-width signal perturbation method (PSPM). This paper points out that there are differences between these methods, and the loop gain measured by the PSPM can be more easily used in the guidance of the controller design. Since the circuit implementation of the PSPM is not easy, the additional PWM modulation method (APMM) and the sample-and-hold method (SHM) with uncomplicated circuits are proposed. The experiment results verify the correctness of the theoretical analysis and the proposed loop gain measurement methods.
When we use BP neural network to forecast the wind power, the selection of input variables is the key issue that affects the forecasting results. This paper proposes a method using rough set theory to solve this probl...
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When we use BP neural network to forecast the wind power, the selection of input variables is the key issue that affects the forecasting results. This paper proposes a method using rough set theory to solve this problem. On the basis of considering the correlation of the wind turbines, we use the Rough-Set analysis methods extract turbines which are strong associated, then use the wind power data of them as the partial inputs of BP neural network and build the RS-BP model(Neural network based on Rough-Set). For the case of wind power data missing, we use the RS-BP to complete the missing data. Then, we use the completed wind power data to forecast the wind power data. This method can select the inputs of neural network reasonably and has the better prediction accuracy. The numerical example shows that this method is effective and feasible.
In cascade AC systems, the impedance interaction between the source module and the load module may cause overall system instability. The generalized Nyquist stability criterion can be applied to characterize the stabi...
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ISBN:
(纸本)9781479967698
In cascade AC systems, the impedance interaction between the source module and the load module may cause overall system instability. The generalized Nyquist stability criterion can be applied to characterize the stability of cascade three-phase AC systems. But it is usually very complicated and cannot directly reveal effective control strategy to alleviate the interaction problem. Based on three-phase voltage source PWM rectifier, this paper proposes a simplified stability criterion for three-phase AC systems. An input impedance regulator design method is introduced to alleviate the interaction problem. Finally, a 20kW prototype is built and tested. The experimental results confirm the proposed stability criterion and the input impedance regulator design method.
Power system load flow calculation is one of the most important type of electrical operations. However, due to the uncertainty presence of load and the growing attention to wind resource, traditional deterministic loa...
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Power system load flow calculation is one of the most important type of electrical operations. However, due to the uncertainty presence of load and the growing attention to wind resource, traditional deterministic load flow analysis cannot meet the requirements with severe uncertainty. In the uncertainty load flow calculation methods, fuzzy load flow calculation method can give the possibility of load flow distribution in a very short time. So it plays a big role in the online grid computing. This paper has mentioned about the details of the fuzzy load flow calculation using the incremental method. And then it has applied to practical system-- Ningxia Power Grid 151-bus system. By compare with the results of Monte Carlo simulation method, numerical results have demonstrated the validity and effectiveness of the proposed model and method.
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