Busbar differential protection method and system for flexible direct-current closed-loop intelligent distribution network

Abstract

The invention provides busbar differential protection method and system for a flexible direct-current closed-loop intelligent distribution network. The system comprises N direct-current buses and N direct-current transmission lines. Each direct-current bus is connected with the direct-current transmission lines at intervals, so that the flexible direct-current closed-loop intelligent distribution network is formed. A region which one of the N direct-current buses locates in is a master node convertor station, and regions which other direct-current buses locate in are child node convertor stations. An alternating-current system rectifier station is connected to each direct-current bus. One end of each alternating-current system rectifier station is connected with one direct-current bus through a direct-current transformer and a direct-current switch, and the other end of the alternating-current system rectifier station is connected with one alternating-current system. A user inverter station and a PT (potential transformer) are connected to each direct-current bus further. The system further comprises a busbar differential protector installed on the master node convertor station. The system can support voltage stability to improve voltage quality, and can timely eliminate failures to guarantee normal power supply when buses fail.

Description

technical field [0001] The invention relates to the field of electric power technology, in particular to a bus differential protection method and system for a flexible DC closed-loop intelligent distribution network. Background technique [0002] With the development of power electronic devices and control technology, a new type of semiconductor device—Insulated Gate Bipolar Transistor (IGBT) has been applied in low-voltage systems, making IGBT a voltage source converter for switching devices ( Voltage-Sourced Converter, VSC), and then widely used in industrial drive devices, and after several upgrades of the voltage and capacity of subsequent IGBT devices, the voltage source converter composed of insulated gate bipolar transistors is used in DC transmission. The application in the distribution network becomes a reality. [0003] In the application of DC transmission and distribution network, the converter adopts IGBT valve and two-level (or multi-level) three-phase mechan...

AI Technical Summary

Problems solved by technology

[0007] In order to solve the problem that the interface points of the flexible DC distribution network system currently in operation cannot meet the power supply requirements, and when the DC bus (including PT and other equipment on the DC bus) fails, the power supply reliability cannot be found in time. To greatly reduce the technical problems, the present invention provides a bus differential protection method and system for a flexible DC closed-loop intelligent distribution network, which can provide support for voltage stability, improve voltage quality, and can be eliminated in time when the DC bus fails. failure, ensure normal power supply

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