Method for realizing power distribution network closed loop and photovoltaic concentrated access by adopting flexible DC (direct current) power transmission

Abstract

The invention relates to a method for realizing power distribution network closed loop and photovoltaic concentrated access by adopting flexible DC (direct current) power transmission. Two feeder lines are led out from each of two main transformers respectively and correspondingly; the four feeder lines are correspondingly connected to AC (alternating current) buses through connecting units respectively; in a flexible DC power transmission system, DC buses connected with DC boost ends of photovoltaic power generation modules are correspondingly arranged on two sides of a DC power transmission loop; during normal operation, the load, supplied by transformer substations, of the four feeder lines is smaller than or equal to 75% of the thermal stability limit power of a single feeder line, flexible DC converters in the flexible DC power transmission system operate as inverters, and the electric power sent out by the photovoltaic power generation modules are transmitted to 10 kilovolt feeder lines. According to the method, the power distribution reliability is high, the transformation is small, the comprehensive investment in inverters is reduced, and the method is suitable for an occasion with high requirement for power distribution reliability and needing grid connection of photovoltaic power stations.

Description

technical field [0001] The invention relates to the field of power supply technology and grid connection of photovoltaic power sources, in particular to a method for realizing closed-loop distribution network and centralized access of photovoltaics by using flexible direct current transmission. Background technique [0002] The medium-voltage distribution network in high-reliability power supply areas at home and abroad generally adopts a ring network structure, and its specific operation mode is divided into two types: open-loop operation and closed-loop operation. my country's medium-voltage 10 kV distribution network adopts the "open-loop operation + distribution automation" method, that is, the contact switch between each 10 kV feeder is opened during normal operation, and the 10 kV feeder uses radiation power supply; when the feeder fails, Fault location and isolation are implemented through the distribution automation system, and the contact switch is closed to realize ...

AI Technical Summary

Problems solved by technology

Yang Xiaodong and others proposed a closed-loop structure suitable for my country's 10 kV power grid in the patent "A High-Reliability Closed-Loop Wiring Structure of Medium-Voltage Distribution Network", that is, two circuits are fed out from the low-voltage side of a single main transformer in a substation. Form a closed-loop operation, since only one transformer will provide short-circuit current, so there will be no problem of excessive short-circuit current in the distribution network; its disadvantages are: two feeders form a closed-loop structure, the normal maximum load rate of the line is 50%, and the utilization rate is not high

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