Control method and system for improving power transmission limit of doubly-fed fan under weak power grid

Abstract

The invention discloses a control method and system for improving a power transmission limit of a doubly-fed fan under a weak power grid. The method comprises the steps that port voltage signals of the doubly-fed fan are collected in real time, reactive power reference signals needed for maintaining a constant grid-connected point voltage are obtained through an upper-layer voltage controller, andthen the reactive power reference signals of a stator side and a rotor side are obtained through a reactive power distributor; rotor-side and grid-side reactive controllers generate current referencesignals of rotor-side and grid-side current controllers according to a reactive instruction, and the current reference signals pass through the rotor-side and grid-side current amplitude limiting links to obtain reference signals actually input into the current controllers; the current controller outputs voltage modulation signals required by the rotor converter and the grid-side converter according to the current reference signals; and the converter is controlled to output active power and reactive power to the power grid so that a capacity of the converter is fully utilized, a fan power transmission capacity limit under the weak power grid is effectively improved, and the power transmission stability of the converter after saturation is considered.

Description

technical field [0001] The invention belongs to the technical field of double-fed wind turbines, and more specifically relates to a control method and system for increasing the power transmission limit of double-fed wind turbines under a weak power grid. Background technique [0002] In order to achieve the goal of energy saving and emission reduction, all countries in the world are optimizing their power supply structure, and traditional thermal power generation is gradually being replaced by new energy power generation. Wind power, as the energy source with the most development potential, occupies a large share of new energy power generation. However, a large number of wind energy resources in our country are concentrated in remote areas such as the northwest, while the load center is located in the southeast coast. Therefore, long-distance power transmission has become an important means to solve the current imbalance in power consumption in our country. However, long-di...

AI Technical Summary

Problems solved by technology

For the former, it mainly generates more reactive power by adding synchronous condensers, installing additional energy storage devices or expanding the converter capacity of double-fed wind turbines to maintain the voltage of the common coupling point and then ensure the normal transmission of active power. However, this method inevitably increases the cost, and the installation location of the equipment needs to be carefully considered; for the latter, the current mainstream control method is mainly to improve the control strategy on the rotor side, by modifying the dynamic power factor reference value or changing the external power factor of the rotor side. The loop is set as a voltage loop to improve the power transmission capability, and there are also a few control strategies to improve the power transmission capability through the cooperation of the rotor side and the grid-side converter or by using droop control; however, these control strategies ignore the regulation capability of the grid-side converter or It is because the capacity of the converter on the rotor side and the grid side is not fully utilized, so there is still a large room for improvement in the power transmission capacity of the double-fed fan

Images