A reactive power optimization and coordinated control method for offshore wind power systems

Abstract

The invention provides a reactive power optimization and coordinated control method for an offshore wind power system. The method comprises the steps that a reactive power voltage regulation constraint condition is determined, and correcting is carried out according to the constraint condition; the measured value of the alternating current bus voltage of the VSC-HVDC wind farm side is subtracted from reference voltage, and the difference is input to a PI regulator to acquire the required reactive power compensation amount zref; the alternating current bus voltage on the wind farm side is compared with nominal voltage; and fast voltage emergency control, long time scale voltage control or the combination of fast voltage emergency control and long time scale control are carried out accordingto the relationship between the alternating current bus voltage on the wind farm side and the nominal voltage. The method provided by the invention has the advantages that the fast voltage regulationcharacteristic of WFVSC is fully utilized; the stability of the grid-connected voltage of an offshore wind farm is improved; fast voltage emergency control and long time scale voltage control are combined; and phase-by-phase control is carried out on reactive devices with different time constants at two time levels, optimizing the control effect.

Description

technical field [0001] The invention relates to a reactive power optimization control method, in particular to a reactive power optimization and coordination control method for an offshore wind power system. Background technique [0002] The voltage in the power system is a local quantity, but the frequency is a global or system quantity, and the two are different. Voltage control cannot control a specific node from any node in the system like frequency control. The level of voltage is determined by the distribution of reactive power, and the principle of reactive power voltage control is stratification, division, and local balance. Changing the reactive power or voltage of a certain node can only be controlled in a specific node or adjacent area. Affected by the environment, wind farms are generally built in remote areas. The grid-connected point voltage is a local quantity. It is difficult to implement long-distance control with traditional power stations, because wind f...

AI Technical Summary

Problems solved by technology

First of all, it is difficult for wind farms to maintain a constant active power output during the control cycle like conventional units. When the wind speed fluctuates greatly, the reactive voltage control method for single-section operation information cannot guarantee the control effect in the entire cycle.

Secondly, when the active power output of the wind farm is large, the slow reactive power adjustment makes it impossible to follow the rapid fluctuation of active power. Its frequent or unreasonable actions will reduce the static voltage stability margin of the cluster area, and it is easy to induce reactive power overcompensation. Or voltage instability caused by under-compensation, which eventually causes the high and low voltage protection actions of the wind farm to cause off-grid accidents

[0004] With the continuous expansion of the scale of offshore wind farms and the continuous increase of grid-connected distances, new problems continue to emerge. Due to the particularity of the structure, location, single-unit power generation and transmission technology of offshore wind farms, the reactive power compensation and control of offshore wind farms are more complicated. for complex

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