A method for power coordination control of multi-terminal flexible direct current transmission system

Abstract

A multi-terminal flexible direct current transmission system power coordination control method, the method selects a converter station with a larger rated capacity from the VSC-MTDC system as the main converter station and adopts constant DC voltage control for it, and the remaining converter stations are divided into It is divided into two groups and adopts adaptive droop control and constant active power control respectively. When the unbalanced power in the system is within the adjustment range of the main converter station, the main converter station will adjust it independently. When the main converter station is fully loaded or out of operation When the droop control is used, the excess unbalanced power is adjusted by the converter station using droop control, and the active power output by the converter station is automatically adjusted according to the change of the DC side voltage caused by the unbalanced power, so that the system power can be balanced again. The invention can avoid the phenomenon of voltage exceeding the limit, reduce the voltage fluctuation of the DC side, and make full use of the active power capacity of the converter station. This method can effectively improve the control quality of the multi-terminal flexible DC transmission system and meet the control requirements of the system under different working 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] Multi-terminal flexible DC transmission system is an important part of building a smart grid. Compared with traditional methods, multi-terminal flexible DC transmission has advantages in island powe...

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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