Low voltage traversing control method of wind generator set

Abstract

A response control method for the lower voltage traversing of a wind generating set is characterized in that changing situation of the voltage us of a power network is detected at any time; the power the voltage us of the power network is compared with a reference value of the voltage us of the power network, and a wattless current iqref<*> as well as an effort current idref <*> are obtained by an obtained difference value Delta u through a PI adjustor; the wattless current iqref<*> is taken as the reference value for the inner loop control of the circuit to cooperate with the control strategies of the outer loop of the voltage and the inner loop of the circuit to control a network side inverter and restrain the depreciation of the voltage of the power network as well as the effect loss of the compensating chain of the effect circuit idref<*>. Under the situation that the voltage of the power network declines instantly, the invention can flexibly feed corresponding reactive powers according to requirements, adjust the effect power correspondingly as well, lead the wind generating set to reach a transmission reliability standard similar to a fire generating set, and have the capacity of self adjustment.

Description

technical field [0001] The invention relates to a low-voltage ride-through control method of a wind power generating set. Background technique [0002] The proportion of wind power generation in the world is increasing, and the impact of wind power generators on the power grid can no longer be ignored. Up to now, in the case of grid disturbance, when the grid voltage decreases to a certain value, the wind turbine will automatically disconnect from the grid. With the sharp increase of wind power generation, this method is no longer suitable for grid operation guidelines. In order for the wind turbines to be connected to the grid, grid safety operation guidelines require that the wind turbines have a Low Voltage Ride-Through (LVRT, Low Voltage Ride-Through) function. Countries where wind power dominates, such as Denmark and Germany, have successively formulated new grid operation guidelines. It is required to allow off-grid only when the grid voltage drops below the specifi...

AI Technical Summary

Problems solved by technology

If the over-current protection limit value is reached, the over-current protection relay will be activated, resulting in the wind turbine off-grid

In addition, the protection action of the rotor-side converter will reduce the electromagnetic torque of the generator, resulting in an increase in the generator speed, and additional torque will be generated due to the increase in rotor acceleration

If the speed protection limit value is reached, the wind turbine will disconnect from the grid and stop

At the same time, if the wind farm is disconnected due to the drop of the grid voltage, the wind power system will lose a larger part of active and reactive power, which will further aggravate the system failure. Feed a part of reactive power to suppress the further drop of grid voltage, so that the wind turbine can keep running continuously without disconnecting from the grid

[0004] At present, the main reactive power compensation devices include capacitors, reactors, etc., but these devices cannot feed reactive power to the grid in time and in sections, and cannot meet the requirements of the grid voltage changing at any time

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