A Coordinated Secondary Voltage Control Method Considering Reactive Power Adjustment Capability of Wind Farm

Abstract

The invention relates to a coordinated secondary voltage control method considering the reactive power regulating capability of a wind farm, and belongs to the technical field of automatic voltage control in an electric power system. The coordinated secondary voltage control method comprises the following steps: firstly, collecting grid operating state data within a control area; secondly, judging whether voltage levels between a generator and each of wind farm nodes within the area are qualified or not, and if an unqualified voltage level exists, regulating a reactive power compensating device under the wind farm node with the unqualified voltage and considering the reactive power regulating capability of the wind farm for coordinated and optimal calculation; finally, according to a calculated reactive power distributing value, judging the balance degree of reactive distributions of all the generators including the wind farm, and if the reactive distributions do not accord with a calculation result of coordinate optimization, entering an inner control system of the wind farm for regulation by taking an optimization calculation result as a regulating command and after the wind farm side receives the voltage level regulating command, issuing a control command by the control system in the wind farm and uploading the reactive regulating amount. By adopting the coordinated secondary voltage control method, the stability and economy of the wind farm running can be improved.

Description

technical field [0001] The invention belongs to the technical field of power system voltage control, and in particular relates to a coordinated secondary voltage control method including the influence of wind power access. Background technique [0002] In recent years, wind power has developed rapidly at an unprecedented speed. According to China's "New Energy Industry Revitalization Plan", China will build seven 10 million-kilowatt wind power bases in Jiuquan, Gansu and other regions. According to the State Council's Medium and Long-term Development Plan for Renewable Energy, by 2020, the installed capacity of wind power will reach 150 million kilowatts. [0003] Among them, the inherent intermittent characteristics of wind power generation will bring great challenges to the operation and dispatch of the power grid, and the problem of reactive power and voltage caused by it has also attracted increasing attention. [0004] At present, there are two characteristics in the ...

AI Technical Summary

Problems solved by technology

[0005] (1) Lack of local control, large voltage fluctuations in wind farms, difficult to meet the voltage assessment requirements of the power grid

[0006] At present, the wind turbines in most wind farms are set in the constant power factor operation mode, and the reactive power does not support online adjustment. It is in the state of manual switching, the response speed is slow, and effective automatic control cannot be realized

Some wind farms are equipped with static var compensator (Static Var Compensator, SVC) and SVG static var generator (static var generator, SVG) and other dynamic var compensation equipment, but in order to meet the assessment requirements for reactive power exchange with the main grid, the SVC Such automatic adjustable devices operate in the control mode of zero power factor cutoff, and take the power factor exchanged with the main network as the control target, which does not support maintaining the stability of the field voltage, and the dynamic reactive power compensation function is not fully utilized when the voltage fluctuates.

[0007] (2) Fragmentation, lack of coordination, leading to large-scale fan off-grid accidents in severe cases

The voltage control on the grid side only sees the local voltage of the wind farm converging station, and does not fully consider the voltage distribution of the wind farm side connected to it. It may be due to capacitor over-investment or untimely removal that the wind turbine terminal voltage exceeds the limit and eventually trips.

[0012] (2) The internal control of the wind farm lacks the concept of coordination

Generally speaking, there are strict requirements on the number of actions of the capacitive reactor throughout the day and the time interval between two consecutive actions, which cannot achieve rapid and continuous adjustment, so it cannot effectively solve the problem of large voltage fluctuations in wind farms

[0037] (2) At present, the capacity of capacitors equipped in wind farms is relatively large, but they are all controlled by the wind farm alone, lacking unified management, which leads to unreasonable switching of capacitors in each wind farm, which will aggravate the severity of faults at certain times

[0038] (3) The reactive power compensation capability of the capacitor depends on the voltage level. When the voltage level is low, the reactive power compensation capability it can provide is correspondingly reduced, which is not conducive to effectively supporting the grid voltage level.

[0041] However, the magnetic control reactor MCR (magnetic control reactor) type SVC equipped in the wind farm now uses the excitation of the inductance to adjust the inductance value. Generally, the response speed is slow and the adjustable capacity is small, so it is difficult to provide strong support when the voltage fluctuates violently.

The thyristor controlled reactor TCR (thyristor controlled reactor) type SVC uses the switching of semiconductor components to control the on and off of the inductance, thereby adjusting the value of the inductance, but it will generate a large number of harmonics, which requires multiple sets of filter circuits. use

[0042] SVG has the advantages of fast response, can filter out grid harmonics, and adjust voltage three-phase unbalance, but due to its high price, it is difficult to be widely used in wind farms

[0043] In addition, most of the SVC devices equipped in existing wind farms are set to operate in a constant power factor mode, which cannot provide reactive power support to the grid when needed

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