Coordinated control method and system for multi-terminal flexible direct current transmission

Abstract

The present invention provides a coordinated control method and system for multi-terminal flexible direct current transmission, including several converter stations adopting a multi-point voltage control strategy, wherein at least one converter station is selected as the main power balance station, and the remaining converter stations are auxiliary power balance stations ; The main power balance station adjusts its own power reference value according to the power reference value of other converter stations or the actual measured power, and quickly adjusts the system power when the power flow of the DC system changes to maintain the DC power grid in a stable state. Operation at the standard voltage; auxiliary power The balance station participates in the adjustment during the dynamic process, and the auxiliary power balance station accurately transmits active power according to the power reference value specified by the system in the steady state. The invention selects the main power balance station to take the initiative to undertake the power balance task, responds quickly, improves the dynamic characteristics of the DC voltage of the system, ensures that the system operates at a standard voltage under steady-state conditions, ensures the transmission power accuracy of each converter station, and reduces the DC voltage droop control. It is difficult to set the slope and has low requirements for communication.

Description

technical field [0001] The invention belongs to the technical field of flexible direct current transmission, and relates to a coordinated control method and system for a multi-terminal flexible direct current transmission system. Background technique [0002] With the gradual scarcity of energy and environmental pollution, the demand for new energy grid connection is getting higher and higher, and the multi-terminal flexible DC transmission technology has gradually become one of the main options for new energy grid connection. However, the large power fluctuations brought about by the new energy grid connection put forward higher requirements for the multi-terminal flexible DC transmission system. In order to maintain power balance and voltage stability, the multi-terminal flexible HVDC transmission system needs a corresponding coordinated control strategy. At present, the main control strategies include master-slave control strategy and its improved control strategy, DC vo...

AI Technical Summary

Problems solved by technology

[0003] The master-slave control strategy and its improved control strategy set the DC voltage. The converter station does not respond quickly enough to the DC power flow change, which easily leads to the overvoltage of the DC system.

The DC voltage droop control strategy uses the voltage deviation of the converter stations at each end to complete the system power balance, which will cause the converter stations to deviate from the standard operating voltage under steady-state conditions and the power control accuracy of each converter station is poor.

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