Photovoltaic grid-connected power generation system and direct current bus voltage control method thereof

Abstract

The invention discloses a photovoltaic grid-connected power generation system and a direct current bus voltage control method thereof. The photovoltaic grid-connected power generation system comprises N photovoltaic direct-current modules, N diodes, a direct current bus capacitor and a grid-connected inverter. The photovoltaic direct-current module comprises a photovoltaic assembly and a direct-current converter. Each photovoltaic direct current module output is connected in parallel with one diode and the photovoltaic direct current modules are connected in series with each other so as to form a direct current bus. The direct current bus voltage control method is characterized in that: the grid-connected inverter automatically adjusts a direct current bus voltage according to changes of system output power so that the direct current bus voltage is reduced with the reduction of the system output power. The photovoltaic grid-connected power generation system of the invention has the following advantages that: generating efficiency is high; system reliability is high; maintenance is easy; hot plug of the photovoltaic direct current module can be supported and so on. By using the direct current bus voltage control method, the system generating efficiency can be effectively increased and a system redundancy operation capability can be improved too.

Description

technical field [0001] The invention belongs to the technical field of power electronic converters, in particular to the technical field of power converters in the technical field of new energy power generation, and in particular to a photovoltaic grid-connected power generation system and a bus voltage control method thereof. Background technique [0002] Photovoltaic grid-connected power generation is the most important way for solar power generation applications. According to statistics, more than 90% of the installed capacity of photovoltaic power generation equipment in the world is grid-connected applications. This is because grid-connected applications have advantages such as low cost and maintenance-free compared with independent photovoltaic systems. . [0003] Common photovoltaic grid-connected power generation systems include centralized, string and multi-string, and AC modular structures. The centralized photovoltaic power generation system is to connect a large...

AI Technical Summary

Problems solved by technology

However, since the output power and voltage of photovoltaic modules are relatively low, while the grid voltage is relatively high, the implementation of photovoltaic grid-connected inverters in AC modular systems is complicated, energy conversion efficiency is low, reliability is low, and costs are high. In addition, there are problems such as complex connection lines, high cost, and large loss when forming a high-power system

[0004] In the entire solar photovoltaic grid-connected power generation system, the cost of photovoltaic cells accounts for the highest proportion of the total system cost, and its price is relatively expensive. On the other hand, the photoelectric conversion efficiency of photovoltaic cells is low. In order to reduce the unit power generation of photovoltaic grid-connected systems The design and realization of high-efficiency photovoltaic grid-connected power generation system is the constant pursuit of the goal in the field of photovoltaic grid-connected power generation; with the large-scale installation and application of photovoltaic grid-connected power generation systems, users are more concerned about the reliability and System maintainability, fault-tolerant operation capability, etc. also put forward higher requirements

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