Wind power station LVRT (low voltage ride through) device and control method thereof

Abstract

The invention relates to a wind power station LVRT (Low Voltage Ride Through) device which comprises a wind power station, electric reactors, diodes, adjustable voltage sources, a circuit breaker and a grid system. One adjustable voltage source is connected in parallel with one diode after being connected in series with one electric reactor to form one group of fault current limiting circuit; and after two groups of fault current limiting circuits are connected in series, one end of the obtained circuit is connected with the wind power station and the other end of the obtained circuit is connected with the grid system by the current breaker. The wind power station LVRT device is low in cost and easy to implement. When the LVRT function is implemented, the short current limiting capacity is improved; and by the non delay input of the current limiting electric reactors connected in series, the large-area talk around accident caused by the short circuit inside the wind power station can be avoided. The wind power station LVRT device has low requirement for the control characteristic of a unit plant; and a power electronic valve string of the wind power station LVRT device adopts a diode set string with low cost, large through-current capacity and strong short-time overload capacity, so that the system cost is reduced.

Description

technical field [0001] The invention relates to the technical field of wind power generation, in particular to a low-voltage ride-through device for a wind farm and a control method thereof. Background technique [0002] The existing research on low-voltage ride-through technology of wind farms mainly focuses on: 1. Improving the low-voltage ride-through capability of wind turbines and the reactive power support capability during ride-through (improving system stability); 2. Adopting static var compensators ( Fast dynamic reactive power compensation devices including SVC), static synchronous compensator (STATCOM), etc., help wind turbines recover terminal voltage during grid voltage drop, and suppress overvoltage after voltage fault recovery, so as to improve wind farm failure Ride-through capability; 3. By adding parallel resistors, series resistors and other active power consumption devices to adjust the active power, absorb excess active power without consuming reactive p...

AI Technical Summary

Problems solved by technology

Due to the slow action speed of the mechanical switch (about 40 milliseconds to 100 milliseconds regardless of the detection and control time), and when a voltage fault occurs in the power grid, the reactive current of the asynchronous wind turbine can reach the rated value of the unit instantaneously. More than ten times, it will bring great difficulties to the safe breaking of the circuit breaker

However, the economy and safety of using controllable power electronic switches are poor (bidirectional thyristor high-voltage valve strings also need to break several times the rated current)

For the above reasons, this method has not been applied in practice

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