Control method of multi-terminal offshore wind power flexible direct current sending-out system

Abstract

The invention provides a control method of a multi-terminal offshore wind power flexible direct current sending-out system. The power exchange on the connecting lines among the multi-terminal systems can be effectively controlled through a control mode of superposing the compensation amount of the active power on the direct current voltage loop through a shore station control strategy, meanwhile, the two point-to-point systems can adopt the same control strategy, selection and switching between the control strategies are not needed, and smooth transition of the systems under various working conditions is guaranteed. The power flow among the multi-end systems is better controlled on the premise of solving the coordination control problem of the multi-end systems. Through an energy consumption device DBS control strategy, the energy consumption device can play a better role in the fault period, the system is helped to smoothly pass through the fault, when an alternating current system of a shore station at one end of the multi-end offshore wind power direct current sending-out system has a low-voltage fault, the DBS system needs to be used for absorbing surplus energy according to the fault condition, and meanwhile, the influence on other double-end systems can be ensured to be as small as possible.

Description

Technical field [0001] The present invention relates to the field of flexible DC transmission, in particular a control method of a multi-end sea wind power flexible DC delivery system. Background technique [0002] At present, offshore wind power is flourishing through the flexible DC transmission system. The domestic flexible DC transmission projects under construction are east projects, and there are several German and Netherlands have been shipped and under construction, such as Borwin1, Borwin2, Dolwin1, Dolwin2, Helwin1, Helwind, etc. The above existing projects are dual-end systems for point-to-point transmission. In the double-end system, in order to solve the problem of faults in the shore station, there is often a power consumption device on the DC side of the shore to absorb the communication failure. The energy of the surplus from the sea station. [0003] When the offshore wind power flexible DC transmission system has developed to a certain extent, it is necessary to...

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Problems solved by technology

[0007] Master-slave control needs to switch the control algorithm when a fault occurs or the role of the master-slave is switched, which will cause certain disturbances to the system

Droop control has a high degree of dependence on the droop coefficient, and a reasonable droop coefficient is the prerequisite for its stable and reliable operation. However, multi-terminal systems operate in various ways, and the configuration may change in various ways. It is difficult to adapt a fixed droop coefficient to various working conditions. requirements

[0008] At the same time, the current control method of the energy-consuming device of the double-terminal system is not suitable for the multi-terminal system

At present, the energy-consuming devices of the double-terminal system generally adopt the control method of DC voltage. In the multi-terminal system, multiple DC voltages cannot be controlled at the same time. Therefore, it is necessary to find a control strategy suitable for the energy-consuming devices of the multi-terminal system.

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