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An improved PO and immune MPPT method for PV generating system under partially shaded conditions

Liu L. Q., Liu C. X., Yang G. T., Zheng X. Y., Wang J. S.

Przegląd Elektrotechniczny

2013

R. 89, nr 1a

235--238

The maximum power point tracking (MPPT) for photovoltaic (PV) generating system study on the tracking method at partial shading is very important to improve the output efficiency of costly PV, the objective is to improve the respond speed and extract maximum power under different weather and partial shading conditions. The output characteristics of PV system get more complex than same irradiation because of the continually changing of atmospheric conditions and frequently partially shaded in actual woke state. The nonlinear and multiple local peaks characteristics of PV system at partial shading are considered by using perturbation and observation (PO) method to gain the actual global peak of PV system, and the conventional PO method is improved by using the perturb Pulse-Width Modulation (PWM) method at ideal irradiation and partial shading, and then the artificial immune theory is used to accelerate the response speed and robustness. The proposed improved PO and immune method has an excellent dynamic performance and small oscillation as compared to the traditional PO method under partially shaded conditions.

W artykule opisano algorytm śledzenia maksymalnego punktu pracy (MPPT) dla system paneli fotowoltaicznych, w warunkach częściowego zacienienia. W celu wyznaczenia punktu globalnego MPPT, zastosowano metodę perturbacji i obserwacji (PO). Metoda PO została ulepszona poprzez zastosowanie zmodyfikowanej modulacji PWM przy braku nasłonecznienia i częściowym zacienieniu. W celu zwiększenia dynamiki i odporności algorytmu wykorzystano teorię sztucznej odporności. Proponowana metoda gwarantuje bardzo dobrą efektywność.

The application of the self-adaptive tracking method to the sinusoidal phase modulating interferometry

He G., Lu Y., Liao C., Zeng Z.

Optica Applicata

2009

Vol. 39, nr 1

109--122

In this paper, we analyze theoretically the accuracy of the surface profile measurement in a sinusoidal phase modulating interferometer, derive the relative error formula, and investigate the influence of spectral leakage on the measurement accuracy. The theoretical results show that when the offset of sampling frequency from its theoretical ideal is outside the range of - 0.188% to +0.075%, the spectrum leakage results in an relative error greater than ?/320 nm, and thus the spectral leakage is not negligible. In order to eliminate the influence of the spectral leakage, a self-adaptive tracking method is proposed. The tracking method can adjust automatically the sampling signal frequency in such a way that the sampling signal frequency is an integer multiple of the modulating signal frequency. The simulation and experimental results show that the problem of the spectrum leakage can be solved with the proposed technique, and therefore the measurement accuracy and reliability of the SPM interferometer are enhanced.