Power circuit and photovoltaic power generation system including power circuit

Abstract

The invention discloses a power circuit and a photovoltaic power generation system including the power circuit. The power circuit is a two-stage topological power circuit. The first stage is a BOOST circuit which processes an input low-voltage direct current into a direct voltage of which the output voltage decreases with time. The second stage is a CCFL conversion circuit. Because the CCFL conversion circuit works in open loop, the peak value of the sinusoidal alternating current output by the CCFL conversion circuit is directly proportional to the working voltage of the CCFL conversion circuit. The voltage decreases with time, namely, the peak value of the sinusoidal alternating current output by the CCFL conversion circuit decreases with time. Thus, the effective value of the sinusoidalalternating current also decreases with time, and an attenuated sinusoidal alternating current voltage is obtained. The voltage acts on the two ends of an activated photovoltaic string, which makes the voltage waveform delta(U) / dealt(t) output by the power circuit small. Therefore, the service life of the photovoltaic string is prolonged, and the radiation to the environment is low. Moreover, thepower circuit of the invention is simple to realize and low in cost.

Description

technical field [0001] The invention relates to a power supply circuit for a photovoltaic power generation system, in particular to a power supply circuit for activating aging photovoltaic strings. Background technique [0002] With the expected depletion of fossil energy and the environmental pollution it brings, the research and application of renewable clean energy has been highly valued by countries all over the world. Among them, wind power generation and photovoltaic power generation technology have become the main research hotspots. Photovoltaic power generation is the abbreviation of solar power generation. The development and research of photovoltaic power generation in my country started in the 1970s, entered a period of stable development in the 1990s, and began to focus on the research of solar photovoltaic power generation in the 21st century. In 2000, my country's photovoltaic technology has entered the stage of large-scale grid-connected power generation. [0...

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Problems solved by technology

[0018] In addition, a photovoltaic power generation system and a voltage compensation method are disclosed in the Chinese invention patent application with the publication number CN107086601A. The patent application uses the pulse voltage output by the voltage compensation device to perform voltage compensation on the photovoltaic strings, thereby recovering the voltage generated by the PID effect. However, since the voltage compensation device has no specific implementation method, it only proposes that its function is to output pulse voltage. The pulse voltage given in the specific implementation includes three forms: square wave, triangular wave and trapezoidal wave. Figure 5 the nature of A and Figure 5 C is the same as in Figure 5 In A, t1 and t2 are the rising edge and falling edge respectively, which cannot be idealized, and its rising and falling exist for a short period of time, and this is exactly Figure 5 C shows the small waveform

These three kinds of pulse voltages ΔU / Δt vary greatly, which will lead to peeling and cracking of the photovoltaic strings and shorten the service life; and the pulse voltage directly acts on the photovoltaic strings, because it is difficult for the photovoltaic strings to achieve electromagnetic shielding, which makes it harmful to the electromagnetic environment of the environment. very high radiation

well known, such as Figure 5 A. It has a lot of harmonics. Although photovoltaic facilities are mostly installed in barren and uninhabited areas, the electromagnetic radiation is very large. It still causes great electromagnetic environmental pollution through the reflection of the ionosphere in the atmosphere.

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