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Xuanyin W.,Zhejiang University | Xiaoxiao L.,Liaoning Solar Energy R and D Co. | Fushang L.,Shandong Electric Power Research Institute
Expert Systems with Applications | Year: 2010

The oscillation in electro-hydraulic regulating system is one of the main reasons leading to the oscillation of electric power system. In this article the influence of internal leakage and plugging of servo valve on the characteristic of the regulating system was analyzed. With the simulation in AMESIM it was found that the leakage of the power stage spool, the plugging of nozzle and orifice could both cause the oscillation of regulating system when the system oil pressure fluctuated. The fluctuation of piston displacement and oil pressure in oil servo motor in different fault state were analyzed. For preventing regulating system from oscillation it was needed to diagnose fault in the servo valve. Taking single leakage for example the change of parameters such as regulating time, steady displacement, and system frequency response, etc. were analyzed. The characteristic table of different fault was given based on simulation. In diagnosis particle swarm optimization (PSO) arithmetic was combined with BP neural network. The weight and threshold values were optimized by PSO arithmetic and five characteristics such as the piston displacement and system frequency were selected as the input of network. The results show that the PSOBP arithmetic has quick convergence speed and good generalization ability, with which the diagnosis of fault in servo valve can be done effectively. © 2009 Elsevier Ltd. All rights reserved. Source

Zhao T.,Dalian University of Technology | Ju Z.,Shenyang Institute of Engineering | Wang H.,Shenyang Institute of Engineering | Wei X.,Dalian University | And 2 more authors.
Proceedings - 2010 International Conference on Intelligent System Design and Engineering Application, ISDEA 2010 | Year: 2011

In the system of the PV grid-connected generation, because of the dispersion of the PV panel, difference of the sun radiation condition and the shadow of a part of the PV panel, they will cause the serious loss of energy for the parallel PV panel. In order to overcoming energy loss and raise the efficiency of the PV system, a new maximum power point tracking method called distributed variable step duty ratio perturb method is put forward. The distributed MPPT method overcomes the shortcomings to generate electricity quantity to descend because of the dispersion of the PV panel. The variable step duty ratio perturbing method speed quickly and is more suitable for this kind of distributed generation system. The hardware adopts DC/DC electric circuit to regulate PWM duty ratio. The software adopts TMS320-2812. An example is given to show that this method is able to realize distributed MPPT. In addition, the calculation speed of the approach is quick, accuracy of the approach is better, and the system has a high stability. © 2010 IEEE. Source

Zhang F.,Shenyang University of Technology | Zhu S.,Shenyang University of Technology | Yin X.,Shenyang University of Technology | Yin X.,Liaoning Solar Energy R and D Co. | Teng Z.,Shenyang University of Technology
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2013

According to the features of grid-connected PV microinverter controller, an interleaved flyback with a simple and isolated structure was used. In this paper, by simplifying the circuit model of flyback converter, the converter's control characteristics is analyzed, and the current which obtained from maximum power point tracking (MPPT) control is made as the benchmark, and then control the flyback transformer original side with the average current control method to realize the half sinusoidal current output. For the interleaved flyback converter may appear load imbalance, a load balance control loop is proposed. Establish a mathematical model of the photovoltaic cell, and deduce the utilization relationship between input decoupling capacitor and the photovoltaic cell panel. By choosing the appropriate input capacitance, the efficiency of system is improved effectively. At last, the effectiveness of the controller is validated in the Matlab/Simulink simulation environment, and a better output waveform is achieved from a converter test. Source

Li X.,Tsinghua University | Zhao Z.,Tsinghua University | Ju Z.,Liaoning Solar Energy R and D Co.
Advanced Materials Research | Year: 2013

The method that dividing a year into multiple time periods and calculating the optimum tilt angle of PV panels in every period is proposed. Calculation software is developed using Labview language. Taking some region in Liaoning province for example, the yearly radiation under fixed inclination, two inclinations and three inclinations every year are compared. The capital investment and increased revenue in the case of fixed inclination, adjusting the bracket twice a year and adjusting the bracket three times a year are compared. The calculation results show that adjusting the angle twice a year and adjusting it three times a year can increase the overall yield 4.03% and 4.39% respectively. The test platform is built up. And the experiment results show that the generating capacity of the 8th unit after angle adjustment increases significantly comparing with that of the 5th unit under fixed inclination. © (2013) Trans Tech Publications, Switzerland. Source

Wang Y.-X.,Shenyang University of Technology | Wang Y.-X.,Shenyang University | Zhang F.-G.,Shenyang University of Technology | Yin X.-J.,Liaoning Solar Energy R and D Co. | Zhu S.-L.,Shenyang University of Technology
Advanced Materials Research | Year: 2012

A derivation calculation methods for the maximum power point tracking is proposed in this paper. This method is the direct calculation method for the maximum power point tracking, through the calculation of the derivative value of the power to voltage, adjust the change values of occupies emptiescompared, which is used to deduce the voltage and current value, judge whether the derivative of the power to the voltage is zero, if it is ture, the maximum power point is got. Hardware is used the method to regulate the duty ratio of PWM in DC/DC boost circuit,though once sampling, it can calculate the value of voltage and the duty ratio at maximum power point. The prototype experiments using DSP2812 chip verify that the inverter can better realize the most power tracing, high accuracy, and the system has the high stability. © (2012) Trans Tech Publications, Switzerland. Source

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