Maximum power tracking control method for monopole three-phase photovoltaic grid-connected system

A technology of maximum power tracking and control method, which is applied in the direction of photovoltaic power generation, single-network parallel feeding arrangement, etc., can solve the problems of misjudgment of disturbance direction, insufficient tracking accuracy, slow tracking speed, etc., and achieve strong self-adaptive ability and tracking The effect of high precision and fast tracking

Inactive Publication Date: 2009-11-04
SOUTHEAST UNIV
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Problems solved by technology

Because if the Step setting is too large, the tracking accuracy will be insufficient, and the operating point of the photovoltaic array will always oscillate near the maximum power point; on the contrary, if the Step setting is too small, although the tracking accuracy is improved, the tracking speed is very slow, and the system is tracking A lot of energy is wasted in the process
In addition, when the external environmental conditions change rapidly, this maximum power point tracking method may misjudge the disturbance direction

Method used

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  • Maximum power tracking control method for monopole three-phase photovoltaic grid-connected system
  • Maximum power tracking control method for monopole three-phase photovoltaic grid-connected system
  • Maximum power tracking control method for monopole three-phase photovoltaic grid-connected system

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Embodiment Construction

[0035] The present invention is specifically realized through the following technical solutions:

[0036] 1) Detect the A, B, and C three-phase voltage signals of the mains grid, and obtain the grid voltage vector rotation angle θ through the phase-locked loop PLL method;

[0037] 2) Detect the three-phase current signals of the inverter output terminals A, B, and C, and use the rotation angle θ in step (1) to perform dq rotation vector transformation to obtain the DC current component i in the synchronously rotating dq axis coordinate system d i q ;

[0038] 3) Detect the output voltage U of the photovoltaic array pv , current I pv , the current sampling time i is obtained from formula (3) (i is a natural number and i≥2, each time the photovoltaic grid-connected system starts to operate, i increases from the initial value of 2 until the system stops running, and then the initial value is changed to 2 ) and the output power P of the photovoltaic array at the previous momen...

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Abstract

The invention belongs to the field of application of photovoltaic power generating system control technology, and relates to a maximum power tracking control method for a monopole three-phase photovoltaic grid-connected system. The method comprises the following steps of: firstly, by testing voltage and current outputted by a photovoltaic array, working out a differential coefficient k of the output power to the voltage of the photovoltaic array and a change rate delta k of the k; secondly, according to the k and an output Step1 of a fuzzy controller (an input is k and delta k, and the output is Step1), jointly determining the disturbance step length and direction of a disturbance voltage delta U which is superposed on a reference voltage U ref of a maximum power point of the photovoltaic array, and making the U ref quickly iterative and then converged at the optimal reference voltage corresponding to the maximum power point of the photovoltaic array under the current environment; and finally, realizing the quick and accurate tracking of the output voltage of the photovoltaic array on the U ref by a double closed loop control system consisting of a voltage PI controller and a synchronous vector current PI controller with feedforward compensation.

Description

technical field [0001] The invention relates to a maximum power tracking control method of a single-stage three-phase photovoltaic grid-connected system, belonging to the application field of photovoltaic power generation system control technology. Background technique [0002] For photovoltaic grid-connected systems, the most important issue is how to improve the power generation efficiency of the system and the working stability of the entire system. Since the single-stage photovoltaic grid-connected system has only one energy conversion link, the system has a simple structure, high efficiency and stability, and has become a research hotspot at home and abroad. Generally, its control system adopts multi-loop control, that is, the maximum power point tracking MPPT link firstly gives the maximum power point reference voltage U of the photovoltaic array ref , and then control the output voltage U of the photovoltaic array through a double closed-loop control system composed ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38
CPCY02E10/58Y02E10/563Y02E10/56
Inventor 郑飞费树岷周杏鹏刘庆全
Owner SOUTHEAST UNIV
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