Power distribution method for multiple constant direct current voltage stations in multi-terminal flexible direct current power transmission system

Abstract

The invention discloses a power distribution method for multiple constant direct current voltage stations in a multi-terminal flexible direct current power transmission system. At least two conversion stations are constant direct current voltage stations controlled by using direct current voltage slope, and the rest conversion stations are constant power conversion stations controlled by using constant active power; the multi-terminal flexible direct current power transmission system is provided with n constant direct current voltage stations, m constant power conversion stations and a power distribution unit; the power distribution unit is provided with a power feedback calculation unit and n direct current voltage control units connected with the constant direct current voltage stations one to one; the power feedback calculation unit is provided with n filters and an adder; each direct current voltage control unit is provided with a distributor, a first comparator, a proportional integrator, a second comparator and a direct current voltage slope controller respectively; each constant direct current station is provided with a direct current voltage slope control unit, an outer ring voltage controller, an inner ring current controller, a reverse PARK converter and a converter valve. The system operation voltage is stabilized to rated voltage.

Description

technical field [0001] The invention belongs to the technical field of multi-terminal flexible direct current transmission systems, and in particular relates to a power distribution method for multiple constant direct voltage stations in the multi-terminal flexible direct current transmission system. Background technique [0002] The multi-terminal flexible direct current transmission system is a flexible direct current transmission system that contains more than two VSC converter stations in the same direct current network. Its most notable feature is that it can realize multi-power supply and multi-drop power receiving. As a flexible and fast power transmission method, multi-terminal flexible DC transmission technology has broad application prospects in the fields of wind power and other new energy grid integration, construction of urban DC distribution networks, and other fields. [0003] An important prerequisite for the stable operation of the multi-terminal flexibl...

AI Technical Summary

Problems solved by technology

[0004] The constant DC voltage slope control method can adopt the voltage-active power drop characteristic or the voltage-current drop characteristic. The slope is generally set according to the capacity, but there are two problems with the constant DC voltage slope control. The first problem is due to The constant DC voltage station adopts the DC voltage slope control. When the actual power deviates from the rated power of the droop characteristic design, the DC voltage will deviate from the rated voltage. The second problem is when designing the power distribution among multiple constant DC voltage stations. In the prior art, the line resistance is usually ignored, which causes the power distribution between multiple constant DC voltage control stations to deviate from the designed distribution ratio

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