String-type photovoltaic inverter AC side parallel connection structure and photovoltaic grid-connected unit

Abstract

The invention discloses a string-type photovoltaic inverter AC side parallel connection structure, which realizes connection between string-type photovoltaic inverters and AC combiner boxes. The AC sides of two or more than two string-type photovoltaic inverters are connected in parallel directly to form a basic unit; and each basic unit is connected to the corresponding AC combiner box through a cable. The structure above, under the condition of not influencing parallel power generation of existing string-type photovoltaic inverters, can reduce cable connection complexity at the AC sides, thereby reducing power station cost, reducing operation and maintenance workload of photovoltaic power stations in long-term generating process and improving return rate of investment of the photovoltaic power stations. The invention also discloses a photovoltaic grid-connected unit.

Description

technical field [0001] The present invention relates to a parallel wiring structure, in particular to a parallel wiring structure on the AC side of a string photovoltaic inverter, and a photovoltaic grid-connected unit based on the wiring structure. Background technique [0002] In recent years, string photovoltaic inverters have gained more and more applications in photovoltaic power plants. In a photovoltaic power station with a capacity of MW or above, 1 MW is usually designed as a basic grid-connected unit, and dozens of string inverters are connected through AC combiner boxes and step-up transformers, and the voltage is boosted to 10kV / 35V , connected to the 10kV / 35kV power grid of the overall photovoltaic power station. [0003] In the existing photovoltaic wiring scheme, a single string inverter is the basic power generation unit of the power station, and an AC combiner box constitutes the primary confluence basic unit of the AC side of the photovoltaic power station...

AI Technical Summary

Problems solved by technology

[0006] (1) The string inverter is installed near the photovoltaic array, and the AC combiner box is generally installed in the center of several connected string inverter units. Since each inverter has at least 3 AC cables on the AC side Output, the number of AC cables for the entire string photovoltaic grid-connected unit is very large, the wiring is complicated, and the workload is heavy

[0007] (2) Every time an AC combiner box is connected to an inverter, a branch circuit breaker needs to be installed correspondingly. There are many circuit breakers in the entire 1MW photovoltaic grid-connected unit. Increased operation and maintenance workload during subsequent power plant operation

[0008] Based on the above analysis, in the existing connection structure, the AC cables of each string inverter must be connected to the AC combiner box, the number of cables is large, and the length of a single cable is large, which needs to be improved

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