LVRT (Low Voltage Ride Through) method for wind power station

Abstract

The invention provides an LVRT (Low Voltage Ride Through) method for a wind power station. The method comprises the following steps of: adding a series resistor R0 in the circuit of a doubly fed wind-driven generator, wherein the switching of the series resistor is controlled by virtue of a by-pass switch, and the by-pass switch in an initial state is closed; calibrating the resistor R0; determining control strategies of a first static synchronous compensator and a second static synchronous compensator, and enabling the first static synchronous compensator and the second static synchronous compensator to emit reactive power limit by virtue of the control strategies; and formulating a judging criteria according to the outlet voltage drop values of a first wind power station and a second wind power station so as to control the switching of the resistor R0; under a condition A or condition B, setting the second static synchronous compensator or the first static synchronous compensator as a reactive power limit control mode, and controlling the second static synchronous compensator or the first static synchronous compensator to return to a normal control mode by virtue of a delta U2 or delta U1. The method can be used for preventing the linkage action of a tommy bar, compensating the reactive power shortage to the greatest extend and improving the outlet voltage, so that a DFIG (Doubly Fed induction Generator) successfully realizes LVRT.

Description

technical field [0001] The invention relates to low voltage ride through, in particular to a low voltage ride through method for wind farms. Background technique [0002] Doubly-fed wind generator (DFIG), as one of the current mainstream wind turbines, has the characteristics of small converter capacity, independent decoupling control of active power and reactive power, and its share in the power grid has increased rapidly year by year. When the power grid failure causes the voltage drop at the grid-connected point, if all the wind turbines in the large-capacity wind farm are disconnected from the grid, it will have an adverse effect on the safe operation of the power system and cause power imbalance in the grid. Therefore, it is required to have a certain low voltage ride through (LVRT) capability. [0003] At present, the common LVRT methods at home and abroad mainly include adding a crowbar (crowbar) protection circuit, dynamic resistance, improving DFIG control strategy...

AI Technical Summary

Problems solved by technology

At this time, DFIG is in an uncontrollable state, and DFIG will absorb a large amount of reactive power from the grid, which will have an impact on adjacent wind farms. In severe cases, it may even cause chain actions of crowbars in adjacent wind farms, resulting in a more serious reactive power shortage in the power system. further deterioration of the voltage

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