阅读说明：本技术 一种动态mppt控制方法 (Dynamic MPPT control method ) 是由 李金荣 蒋峰 方刚 黄敏 卢进军 于 2021-08-09 设计创作，主要内容包括：本发明涉及一种动态MPPT控制方法,用于在光照强度变化速度超过设定的速度阈值时控制光伏面板实现MPPT,该动态MPPT控制方法为：在进行动态MPPT控制时,检测光伏面板的发电功率,根据光伏面板的发电功率的变化而调整光伏面板的输出电压,从而实现MPPT。当光伏面板的发电功率变大时,向右调整光伏面板的输出电压；当光伏面板的发电功率减小时,向左调整光伏面板的输出电压。采用变步长策略调整光伏面板的输出电压。调整光伏面板的输出电压时采用的步长随光照强度变化速度的降低而减小、随光照强度变化速度的升高而增大。本发明能够在光照强度快速变化时实现光伏面板的MPPT,从而解决动态MPPT效率偏低的问题。(The invention relates to a dynamic MPPT control method, which is used for controlling a photovoltaic panel to realize MPPT when the change speed of illumination intensity exceeds a set speed threshold, and comprises the following steps: during dynamic MPPT control, the generated power of the photovoltaic panel is detected, and the output voltage of the photovoltaic panel is adjusted according to the change of the generated power of the photovoltaic panel, so that MPPT is realized. When the power generation power of the photovoltaic panel becomes large, the output voltage of the photovoltaic panel is adjusted rightwards; when the generated power of the photovoltaic panel decreases, the output voltage of the photovoltaic panel is adjusted leftward. And adjusting the output voltage of the photovoltaic panel by adopting a variable step strategy. The step length adopted when the output voltage of the photovoltaic panel is adjusted is reduced along with the reduction of the change speed of the illumination intensity and is increased along with the increase of the change speed of the illumination intensity. The invention can realize the MPPT of the photovoltaic panel when the illumination intensity is changed rapidly, thereby solving the problem of low dynamic MPPT efficiency.)

1. A dynamic MPPT control method is characterized in that: the dynamic MPPT control method is used for controlling the photovoltaic panel to realize MPPT when the change speed of the illumination intensity exceeds a set speed threshold, and comprises the following steps: during dynamic MPPT control, the power generation power of a photovoltaic panel is detected, and the output voltage of the photovoltaic panel is adjusted according to the change of the power generation power of the photovoltaic panel, so that MPPT is realized.

2. The method of claim 1 for dynamic MPPT control, wherein: when the generated power of the photovoltaic panel becomes large, the output voltage of the photovoltaic panel is adjusted rightwards; when the generated power of the photovoltaic panel is reduced, the output voltage of the photovoltaic panel is adjusted leftwards.

3. The method of claim 1 for dynamic MPPT control, wherein: and adjusting the output voltage of the photovoltaic panel by adopting a variable step length strategy.

4. A dynamic MPPT control method according to claim 3, wherein: the step length adopted when the output voltage of the photovoltaic panel is adjusted is reduced along with the reduction of the change speed of the illumination intensity and is increased along with the increase of the change speed of the illumination intensity.

5. The method of claim 1 for dynamic MPPT control, wherein: and judging whether the condition of entering dynamic MPPT is met or not according to the difference value of the generated power of the photovoltaic panel in two adjacent MPPT periods, and if so, carrying out dynamic MPPT control.

6. The dynamic MPPT control method of claim 5, characterized by: and when the difference value of the generated power of the photovoltaic panel in two adjacent MPPT periods is larger than a set power threshold value, the condition of entering dynamic MPPT is met.

Technical Field

The invention belongs to the technical field of new energy power generation, and particularly relates to a dynamic MPPT control method.

Background

In a photovoltaic power generation system, a Maximum Power Point Tracking (MPPT) technology is adopted to solve the problem of low photovoltaic power generation efficiency.

In the conventional MPPT control method, a three-point method, also called a hysteresis comparison method, is a tracking method based on a disturbance observation method, and its basic principle is as follows: setting the current working voltage point as a reference point B, setting a point A as a working voltage point for reducing delta U on the basis of the point B, and setting a point C as a working voltage point for increasing delta U on the basis of the point B. Introducing a state variable M, if the power of the point C is greater than or equal to the power of the point B, the M is positive, otherwise, the M is negative; if the power at point A is less than the power at point B, M is positive, otherwise, M is negative. When two M are positive and two are negative, the output voltage is reduced, and when M is zero, the output voltage is unchanged, and the point B is considered as the maximum power point.

The maximum power point accessory shown in fig. 1 may be present, and at this time, when the light intensity changes suddenly, the arrangement mode of the lower half portion in fig. 1 may appear, and for this situation, in the prior art, a scheme of not moving the voltage operating point, waiting for the illumination to be stable, and then tracking is adopted.

From the above analysis, the prior art does not move the voltage operating point when the illumination changes rapidly, but this also causes a new problem, and the actual MPPT voltage point when the illumination changes rapidly causes the following two problems:

(1) when the illumination is rapidly enhanced, the MPPT voltage point of the LED lamp is rapidly shifted to the right at the initial stage of the illumination enhancement, and the actual voltage working point is leftwards biased relative to the MPPT voltage point and is in a state of being always leftwards biased;

(2) when the illumination is weakened rapidly, the MPPT voltage point of the LED lamp is required to move left gradually and move left rapidly when the illumination is weakened to the low-power working condition, and the actual voltage working point is deviated to the right relative to the MPPT voltage point when the illumination is weakened.

Therefore, the following problems can be caused under the condition of dynamic MPPT by adopting the conventional three-point tracking MPPT, namely, when the illumination is rapidly enhanced or weakened:

(1) when the illumination is rapidly enhanced, the actual voltage working point is biased to the left relative to the MPPT voltage point;

(2) when the illumination is rapidly weakened, the actual voltage working point is deviated to the right relative to the MPPT voltage point;

(3) the dynamic MPPT efficiency is affected as the rate of the increase or decrease of the illumination becomes greater, and the dynamic MPPT efficiency decreases as the rate of the change of the illumination increases. Especially, when the illumination is weakened to the low-power working condition, or the illumination is enhanced to a relatively higher power from the low-power working condition, the influence on the dynamic MPPT efficiency is especially obvious.

Disclosure of Invention

The invention aims to provide a dynamic MPPT control method which is suitable for carrying out MPPT when the illumination intensity is changed rapidly so as to improve the photovoltaic power generation efficiency.

In order to achieve the purpose, the invention adopts the technical scheme that:

a dynamic MPPT control method is used for controlling a photovoltaic panel to realize MPPT when the change speed of illumination intensity exceeds a set speed threshold, and comprises the following steps: during dynamic MPPT control, the power generation power of a photovoltaic panel is detected, and the output voltage of the photovoltaic panel is adjusted according to the change of the power generation power of the photovoltaic panel, so that MPPT is realized.

When the generated power of the photovoltaic panel becomes large, the output voltage of the photovoltaic panel is adjusted rightwards; when the generated power of the photovoltaic panel is reduced, the output voltage of the photovoltaic panel is adjusted leftwards.

And adjusting the output voltage of the photovoltaic panel by adopting a variable step length strategy.

The step length adopted when the output voltage of the photovoltaic panel is adjusted is reduced along with the reduction of the change speed of the illumination intensity and is increased along with the increase of the change speed of the illumination intensity.

And judging whether the condition of entering dynamic MPPT is met or not according to the difference value of the generated power of the photovoltaic panel in two adjacent MPPT periods, and if so, carrying out dynamic MPPT control.

And when the difference value of the generated power of the photovoltaic panel in two adjacent MPPT periods is larger than a set power threshold value, the condition of entering dynamic MPPT is met.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the invention can realize the MPPT of the photovoltaic panel when the illumination intensity is changed rapidly, thereby solving the problem of low dynamic MPPT efficiency.

Drawings

Fig. 1 is a schematic diagram of a possible maximum power point accessory when a three-point method is adopted.

FIG. 2 is a corresponding photovoltaic power generation power variation curve when the illumination intensity varies.

Detailed Description

The invention will be further described with reference to examples of embodiments shown in the drawings to which the invention is attached.

The first embodiment is as follows: when the illumination is rapidly enhanced or weakened, the power corresponding to the MPPT of the photovoltaic panel changes at a constant speed, on the basis of a three-point method, when the illumination intensity is gradually enhanced, as shown in the attached drawing 2, the change of the power difference value is inevitably caused, because the power change is theoretically at a constant speed, the power change difference value is nearly unchanged near the MPPT, and if the power change is deviated to the left or the right, the power change difference value changes towards the opposite trend, so that the voltage working point is dynamically adjusted to be stabilized near the MPPT.

Based on the above principle, a feasible method is provided for dynamic MPPT when the illumination intensity changes rapidly as follows:

a dynamic MPPT control method is used for controlling a photovoltaic panel to realize MPPT when the change speed of illumination intensity exceeds a set speed threshold (namely when the illumination intensity changes rapidly), and comprises the following steps: during dynamic MPPT control, the generated power of the photovoltaic panel is detected, and the output voltage of the photovoltaic panel is adjusted according to the change of the generated power of the photovoltaic panel, so that MPPT is realized.

In implementing the above method, a distinction is first made between static MPPT and dynamic MPPT. Whether the condition of entering dynamic MPPT is met or not can be judged according to the difference value of the power generation power of the photovoltaic panels in two adjacent MPPT periods, and if yes, dynamic MPPT control is carried out. And when the difference value of the power generation power of the photovoltaic panel in two adjacent MPPT periods is larger than a set power threshold value, the condition of entering dynamic MPPT is met.

When dynamic MPPT control is carried out, special judgment logic is adopted to dynamically adjust MPPT so that the working voltage of the MPPT is stabilized near the MPPT. When the generated power of the photovoltaic panel becomes large, the output voltage of the photovoltaic panel is adjusted rightwards, namely the output voltage of the photovoltaic panel is increased; when the generated power of the photovoltaic panel decreases, the output voltage of the photovoltaic panel is adjusted leftward, i.e., the output voltage of the photovoltaic panel is decreased. Here, the adjustment amount Δ U of the output voltage to the photovoltaic panel is determined according to the number of times of determining that the generated power of the photovoltaic panel increases or decreases, that is, as the number of times of determining that the generated power of the photovoltaic panel increases or decreases gradually increases, the adjustment amount Δ U of the output voltage to the photovoltaic panel increases each time.

When the output voltage of the photovoltaic panel is adjusted, different change speeds exist when the illumination is enhanced or weakened from the low-power working condition, and in order to better track the MPPT, the output voltage of the photovoltaic panel is adjusted by adopting a variable step size strategy to achieve a better effect. The step length adopted when the output voltage of the photovoltaic panel is adjusted is reduced along with the reduction of the change speed of the illumination intensity and is increased along with the increase of the change speed of the illumination intensity. When the change speed of the illumination intensity reaches a certain limit value, the maximum step length is directly adopted.

The prior art can not well meet the requirement of tracking MPPT under the condition of rapid enhancement or weakening of illumination, so that the efficiency of dynamic MPPT is low. According to the scheme, specific judgment is carried out on the dynamic MPPT to distinguish the dynamic MPPT from the static MPPT, and the problem that the efficiency of the dynamic MPPT is low can be well solved by adjusting the voltage working point according to power change in a targeted manner.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.