Improved DC voltage control strategy applicable to multi-end flexible DC system

Abstract

The invention discloses an improved DC voltage control strategy applicable to a multi-end flexible DC system. The improved DC voltage control strategy comprises the steps of (1) determining a converter station type according to inversion of an active power of a converter station under all working conditions, determining a control mode of the converter station according to the type of the converterstation, and numbering the converter station; (2) determining a DC current allocation coefficient among the converter stations with regard to a receiving-end converter station employing fixed-DC voltage control; and (3) correcting an instruction value of a DC voltage of the converter station, and achieving DC current allocation control of the fixed-DC voltage converter station. The DC voltage instruction valve correction step is added into the converter station with a fixed-DC voltage, indirect control of a DC current and an active power of the converter station can be achieved, the problem of master-slave control unreliability can be solved, the problem that the power cannot be flexibly controlled in DC voltage droop control also can be solved, and the improved DC voltage control strategy has important practical engineering significance.

Description

technical field [0001] The invention belongs to the technical field of electric power transmission and distribution, and in particular relates to an improved direct current voltage control strategy applicable to a multi-terminal flexible direct current system. Background technique [0002] my country's energy resources and load demand are reversely distributed, and long-distance large-capacity UHV DC transmission is developing rapidly; the application of large-scale conventional DC transmission meets the needs of energy delivery in the sending end area and load growth in the receiving end area, but it also poses a threat to grid security. Operation and clean energy consumption have brought significant impacts, mainly because severe AC faults may cause conventional DC multiple commutation failures or even DC blocking. In addition, the reactive power absorbed by conventional DC during the rapid dynamic process of grid faults has increased significantly, resulting in insufficien...

AI Technical Summary

Problems solved by technology

However, the DC voltage droop controller controls the power balance of the DC network in an open loop, so the stable operating point of the system is very sensitive to the parameters of each converter station controller, and there is also the problem that the active power distribution of the corresponding converter station is uncontrollable

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