Power coordinated control method for multi-terminal flexible DC transmission system

Abstract

The invention relates to a power coordinated control method for a multi-terminal flexible DC transmission system. According to the method, a converter station with larger rated capacity is selected from a VSC-MTDC (Voltage Source Converter Multi-Terminal DC) system to serve as a main converter station, constant DC voltage control is performed on the main converter station, the other converter stations are divided into two groups, adaptive droop control and constant active power control are respectively performed on the two groups of converter stations, the main converter station performs regulation independently when the unbalanced power in the system is within a regulating range of the main converter station, and when the main converter station is fully loaded or out of operation, the redundant unbalanced power is regulated by a converter station adopting the droop control, the active power outputted by the converter station is automatically regulated according to DC side voltage changes caused by the unbalanced power so as to enable the system power to achieve a balance again. The power coordinated control method can avoid a phenomenon of out-of-limit voltage, reduce voltage fluctuations at the DC side and make full use of the active power capacity of the converter station. The method can effectively improve the control quality of the multi-terminal flexible DC transmission system, and meet control requirements of the system under different operating conditions.

Description

technical field [0001] The invention relates to a power coordination control method in a DC power transmission system, belonging to the technical field of power transmission and distribution. Background technique [0002] The voltage source converter multi-terminal DC (VSC-MTDC) power transmission technology based on voltage source converter is a kind of technology based on voltage source converter, self-shutdown device and pulse width modulation (PWM) technology. The new power transmission technology has the advantages of being able to supply power to the passive network, avoiding commutation failure, and being easy to form a multi-terminal DC system. It has broad application prospects in areas such as distance power transmission and new urban DC distribution networks. [0003] The multi-terminal flexible DC transmission system is an important part of building a smart grid. Compared with the traditional method, the multi-terminal flexible DC transmission has advantages in ...

AI Technical Summary

Problems solved by technology

[0005] (1) When the traditional fixed-slope droop control is adopted in the converter station, the DC voltage is prone to exceed the limit, and the active power capacity of the converter station cannot be fully utilized during the power coordination control process of multiple converter stations

[0006] (2) The realization of master-slave control has higher requirements on the communication system. When the communication is interrupted, it will lead to voltage instability or even system disconnection

[0007] (3) Voltage margin control is prone to power oscillation during the switching process of the control mode of the converter station, and the selection of the voltage margin is relatively complicated, and it is difficult to determine the priority of multiple backup constant DC voltage converter stations. more difficult to achieve

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