Perturbation and observation method for tracking maximum power point of photovoltaic grid-connected generating system
A technology of maximum power point and perturbation-and-observation method, applied in the field of perturbation-and-observation method, can solve problems such as DC bus voltage collapse and inability to correctly track the maximum power point, achieve hardware cost reduction, eliminate false tracking phenomenon, and track the maximum power point accurately Effect
Inactive Publication Date: 2014-04-02
XIAN UNIV OF TECH
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[0007] The purpose of the present invention is to provide a disturbance observation method for tracking the maximum power point of a photovoltaic grid-connected power generation system, which overcomes the traditional disturbance observation method that easily causes the DC bus voltage to collapse and cannot correctly track the maximum power point under weak light conditions. Disadvantages, reduce hardware cost and increase power generation of photovoltaic array
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[0030] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.
[0031] Define the following symbols: V ref is the photovoltaic array reference voltage, V pv Output voltage sampling signal for photovoltaic array, e v is V pv with V ref The error signal of e v_1 is the previous time V ref with V pv The error signal, V refs is the center point voltage within the voltage disturbance range, dV is the voltage disturbance amount, dV _1 is the previous voltage disturbance, J mx is the forward perturbation bandwidth, -J mx is the negative disturbance bandwidth, LOR is the disturbance unit with direction, I ref is the reference current amplitude signal of the current grid-connected inverter, I ref_1 is the reference current amplitude signal of the previous grid-connected inverter, I m is the maximum I obtained in the disturbance period ref value, j is the count variable, N is the count reference compar...
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The invention discloses a perturbation and observation method for tracking a maximum power point of a photovoltaic grid-connected generating system, which is characterized in that reference current amplitude value signals of a grid-connected inverter serve as alternative signals of output power of the grid-connected inverter, and a controller is used for perturbing photovoltaic array reference voltage in real time and determining the direction of perturbing photovoltaic array reference voltage for next time according to reference current amplitude value signal change before and after the photovoltaic array reference voltage is perturbed. By means of ring closure of a PI regulator, reference current amplitude value signals of the grid-connected inverter for next time can be also obtained while practical output voltage of a photovoltaic array tracks the reference voltage in real time. Repeatedly, a maximum power point tracking function of the photovoltaic array can be realized by perturbing the voltage, observing the reference current amplitude value signal change and regulating reference voltage of the photovoltaic array and the reference current amplitude value signals of the grid-connected inverter for next time. By the aid of the method, voltage collapse of a direct-current bus and incapability of correctly tracking in weak sunlight are avoided, hardware cost is reduced, and generating power of the photovoltaic array is improved.
Description
technical field [0001] The invention belongs to the technical field of solar photovoltaic power generation, and in particular relates to a disturbance observation method for realizing maximum power point tracking of a photovoltaic grid-connected power generation system. Background technique [0002] The cost of solar photovoltaic cells is relatively high, which restricts the rapid development of the photovoltaic industry. Under the premise of high hardware cost, how to ensure the real-time maximum power output of photovoltaic cells is crucial to improving the cost performance of photovoltaic power generation systems. As we all know, the output power characteristics of photovoltaic cells are highly nonlinear. The maximum output power, maximum output power point voltage and current vary with temperature, light intensity and other factors. Only by adopting an effective maximum power point tracking method can the photovoltaic cell be improved. The utilization rate of the power ...
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IPC IPC(8): G05F1/67
CPCY02E10/58Y02E10/56
Inventor 孙向东张琦宋卫章杨惠
Owner XIAN UNIV OF TECH