Solar energy is considered as one of the most effective, less expensive, harmless and less environment pollution effect of renewable energy sources, the problem of using solar power including varying weather condition...
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Solar energy is considered as one of the most effective, less expensive, harmless and less environment pollution effect of renewable energy sources, the problem of using solar power including varying weather condition brings different output power of the photovoltaic (PV) array, which may cause a serious waste of solar power, for solving this problem, a Maximum power Point Tracking (MPPT) strategy is always required to make PV array keep giving maximum power under different environment condition. In this paper, a variable step MPPT based on gradient descent method is proposed for faster and more precise tracking process, a model based on matlab/simulink was established to analysis the performance of the proposed MPPT strategy, simulation results prove that this MPPT method is practical with a better performance than the traditional strategies.
The paper deals with the impact of wind power integration on powersystem small signal stability. The DFIG wind turbine consisting of a back-to-back PWM converter is introduced. Generator model is given first, ignorin...
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The paper deals with the impact of wind power integration on powersystem small signal stability. The DFIG wind turbine consisting of a back-to-back PWM converter is introduced. Generator model is given first, ignoring the transient of stator. The converter control, shaft and pitch angle control diagrams are picked out for a detailed study subsequently. A case study is performed in part three, eigen-analysis of a modified IEEE 14 system is conducted considering the PF and VT control modes of wind farm. The pole map gives an intuitionistic view that DFIG introduces two oscillation modes related to the shaft and VAR controller model respectively. Eigen-structure depicts the electromechanical oscillation modes, and comparison of DFIG and SG case was studied which gives an overall conclusion that DFIG can have a favorable performance. Also the influence of increased penetration of wind power is examined.
Reliable protection and reasonable control run an important role in grid connected PV power generation system. The detection and calculation of real and reactive power are the bases of many inverter resident passive a...
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Reliable protection and reasonable control run an important role in grid connected PV power generation system. The detection and calculation of real and reactive power are the bases of many inverter resident passive and active islanding detection method (IDM). As well as the detection and calculation of real and reactive power also concern with the inverter control of grid connected PV power generation system. In this paper, considering instantaneous voltage and instantaneous current are periodic function about time, think of it in terms of periodic function space to define the inner product and norm, Hilbert space based power theory is proposed. Real power, reactive power and apparent power in Hilbert space based theory are defined. This proposed Hilbert space based power theory provide a novel view for the protection, islanding detection and control of grid connected PV power generation system.
Besides the conventional benefit of improving power flow, distributed generation (DG) can also be used to mitigate voltage sag and reduce line loss. In this paper, a graph and gene based algorithm was proposed to addr...
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Since the digital simulation is one of the basic tools in understanding the modern complex powersystems, its veracity has direct effects on the decision making on the powersystem operation and control. However, the ...
Since the digital simulation is one of the basic tools in understanding the modern complex powersystems, its veracity has direct effects on the decision making on the powersystem operation and control. However, the accuracy of the digital simulation is dependant heavily on the model validity. Among all the dynamic components of the powersystem, the load is one of the most difficult one to be modeled. The difficulty lies in the fact that the scenario when the load model is built is always different from the real situation raised by the faults. So the question naturally arises that whether the measurement-based load model could be applied in the digital simulation when analyzing different operation scenarios. And to what extent does the model keep valid? It is hard to answer these questions because the field data, which constitute the basis of the measurement-based load modeling, are limited. This paper reports our work on validating the load model via RTDS. By simulating various fault situations on a model of a real provincial powersystem in RTDS, we could get a great amount of data to build the model as well as research its validity. Two greatly concerned problems related to the measurement-based load model are addressed in this paper; one is the possibility of applying the load model for various fault scenarios and the other is the validity of the load model when the load composition changes. Suggestions for the measurement-based load modeling practice are also given from the model validation work.
Correctly estimated the number of partial discharge (PD) source is the premise of the power transformer PD location based on ultrasonic array sensors. Therefore, estimation of the number of power transformer PD source...
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ISBN:
(纸本)9781424443673
Correctly estimated the number of partial discharge (PD) source is the premise of the power transformer PD location based on ultrasonic array sensors. Therefore, estimation of the number of power transformer PD source is a very necessary research work. In this paper, we proposed the modified Canonical Correlation Technique (CCT) to estimate the number of transformer PD source. The simulation experiment results confirm the validity of the method.
Due to the heavy calculation and low estimation precision with little signal-to-noise (SNR) of MUSIC (Multiple Signal Classification) algorithm in partial discharge location used ultrasonic phased array, in this paper...
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ISBN:
(纸本)9781424443673
Due to the heavy calculation and low estimation precision with little signal-to-noise (SNR) of MUSIC (Multiple Signal Classification) algorithm in partial discharge location used ultrasonic phased array, in this paper, a new location method is proposed based on Root-Multiple Signal Classification(Root-MUSIC). Firstly, Root-MUSIC algorithm is used for direction of arrival estimating of PD source. Secondly, space location of PD source is realized by crossover location principle. Finally, the result of simulation based on 7×7 plane phased array model vertifies the correctness of the new method.
This paper introduces an over-modulation technique, a continuous extension of space vector PWM (SVPWM) linear control scheme for the three-phase current source rectifier (CSR). The over-modulation range is divided int...
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ISBN:
(纸本)9781424449347
This paper introduces an over-modulation technique, a continuous extension of space vector PWM (SVPWM) linear control scheme for the three-phase current source rectifier (CSR). The over-modulation range is divided into two modes depending on the modulation index (MI). In mode I, the reference angles are derived from the Fourier series expansion of the reference voltage which corresponds to the MI. In mode II, the holding angles are also derived in the same way. The strategy, which is easier to understand graphically, produces a linear relationship between the output voltage and the MI up to six-step operation. The relationship between those angles and the MI can be written in lookup tables or, for real-time implementation, can be piecewise linearized. In addition, harmonic components and total harmonic distortion (THD) of the output voltage are analyzed. When the method is applied to the V/f control of the induction motor, a smooth operation during transition from the linear control range to the six-step mode is demonstrated through experimental results.
Due to the influence of the local noise at the distribution level, the frequency curve obtained from the frequency disturbance recorder (FDR) unit is too non-stationary to observe its wave-front directly, which causes...
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Due to the influence of the local noise at the distribution level, the frequency curve obtained from the frequency disturbance recorder (FDR) unit is too non-stationary to observe its wave-front directly, which causes some problems in the event location estimation method. In this paper, a morphological filter (MF) is employed to extract the wave-front arrival time and the trend of the frequency curve. With the help of the MF, the accuracy of the event location method is greatly improved.
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