Fault ride-through control method for wind power plant through VSC-HVDC grid connection

Abstract

The invention discloses a VSC-HVDC grid-connected fault ride-through control method for a wind power plant, and the method comprises the steps: building a mathematic model of a VSC, and analyzing theoperation characteristics of a system when a power grid breaks down, including the change conditions of the transmission active power of converters at two sides and the change conditions of the voltage of a DC bus when the power grid breaks down; designing a topological structure of the modular energy consumption resistor in the VSCHVDC system; and finally, on the basis of the modular energy consumption resistor, designing a coordination control method in combination with the wind turbine generator, thereby achieving fault ride-through. Aiming at the defects of a traditional fault ride-throughmethod based on a direct-current energy consumption resistor, an improved modular energy consumption circuit is designed, and fault ride-through control over a wind power plant through VSC-HVDC gridconnection is achieved on the basis of the design of the modular energy consumption circuit in combination with a coordination control strategy of a wind turbine generator.

Description

technical field [0001] The invention belongs to the field of smart grids, in particular to a fault ride-through control method for a wind farm connected to a grid through a VSC-HVDC. Background technique [0002] In recent years, with the development of wind power technology, the single-unit capacity of wind turbines has gradually increased, and the scale of wind farms has also increased. The interaction between wind power and traditional power grids has become more and more obvious. For power systems with low wind power penetration, the wind turbines will immediately go off-grid when the grid voltage drops. In this case, the system will not be seriously affected. The automatic off-grid will cause a great impact on the power grid. It seriously threatens the voltage stability and frequency stability of the system, and this negative benefit will hinder the large-scale development of the wind power industry. Therefore, in the context of the increasing proportion of the capaci...

AI Technical Summary

Problems solved by technology

For the case where the doubly-fed wind farm is connected to the grid through the flexible DC transmission system, when a voltage drop fault occurs at the PCC (point of common coupling) of the receiving end grid, the main problem caused is the DC power caused by the unbalanced active power transmitted by the system during the fault period. Overvoltage affects the safe and stable operation of the DC system

The currently used method is to put into the unloading circuit energy-dissipating resistor to absorb active power, but this method requires a large resistance capacity, and the problem of land occupation and heat dissipation brought to the system is very prominent, and it lacks practicability

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