CN110970919B - Control method and system for closed-loop regulation of terminal voltage of wind turbine generator - Google Patents

Abstract

The invention discloses a control method and a system for closed-loop regulation of generator terminal voltage of a wind turbine generator, wherein the method comprises the following steps: a voltage closed loop regulation link based on a quick voltage response control link is connected in series in a current control link of the wind turbine generator inverter; the voltage closed loop regulation link comprises: a difference adjustment link, a delay link, a dead zone link, a first series correction link, a second series correction link, an amplification link and an amplitude limiting link, wherein a reactive current reference value of the wind turbine generator inverter is calculated through the voltage closed-loop adjustment link, and a compensation coefficient of the voltage closed-loop adjustment link is determined; and adjusting the distribution of the reactive current among the wind generation sets according to the compensation coefficient of the voltage closed loop adjusting link, so as to avoid the occurrence of reactive power robbing or reactive circulation among the wind generation sets.

Description

A control method and system for closed-loop regulation of wind turbine generator terminal voltage

technical field

The present invention relates to the technical field of electric power systems, and more particularly, to a control method and system for closed-loop regulation of wind turbine generator terminal voltage.

Background technique

With the gradual completion of global fossil energy mining, the approaching supply, and the intensification of the greenhouse climate, countries around the world have recognized the importance of renewable energy, especially the development of wind power and photovoltaics, and attached great importance to the development of wind power, and the global wind power industry has grown rapidly. develop. Since the 1990s, the average annual growth rate of global wind power installed capacity has remained above 25%, and wind power has become the fastest growing renewable energy source in the world. Wind power is developing rapidly in my country. Since 2012, my country's wind power grid-connected capacity has surpassed that of the United States, becoming the world's largest wind power country. As of the end of 2018, the installed capacity of wind power grid-connected has exceeded 184 million kilowatts, and the total annual power generation has exceeded 366 billion kWh, accounting for 5.2% of the total power generation, an increase of 0.4 percentage points over 2017 and a year-on-year increase of 20%. Due to policy support, cost reduction, maturity of technology and influx of capital, the installed capacity and annual power generation of wind power have maintained rapid growth, and the role of clean alternatives to renewable energy has become increasingly obvious.

The connection of a large number of wind turbines to the power grid has brought a series of major impacts on the security and stability of the power system: random power changes caused by wind changes; short-circuit current characteristics and active and reactive power changes during system failures; steady-state reactive power Control characteristics; the impact of replacing the original conventional power supply on the transient, dynamic, and medium and long-term stability of the power system after large-scale wind power is connected to the system. At present, there are voltage stability problems caused by the failure of DC commutation in the possible raw energy bases sent by HVDC. How to provide reactive power support for parallel wind turbines stably during voltage fluctuations has become an urgent need to solve large-scale wind power grid integration. The problem.

At present, the national standard only requires wind turbines to emit a certain reactive current during low voltage ride-through, and does not require wind turbines to participate in voltage closed-loop regulation during steady-state operation. When wind turbines participate in closed-loop voltage regulation without additional control, multiple wind power plants will appear The phenomenon that the unit grabs reactive power and forms a reactive power circulating current, which not only does not have a positive effect on the system voltage, but may even cause the local voltage to be too high or too low, causing the wind turbine protection action. power, reducing the reactive current compensation effect of the wind turbine.

Therefore, a technology is needed to realize a fast voltage response control technology for closed-loop regulation of wind turbine generator terminal voltage.

SUMMARY OF THE INVENTION

The technical scheme of the present invention provides a fast voltage response control method and system for closed-loop regulation of the wind turbine generator terminal voltage, so as to solve the problem of how to control the fast voltage response for the closed-loop regulation of the wind turbine generator terminal voltage.

In order to solve the above problems, the present invention provides a fast voltage response control method for closed-loop regulation of wind turbine generator terminal voltage, the method includes:

In the current control link of the wind turbine inverter, the voltage closed-loop regulation link based on the fast voltage response control link is connected in series;

The voltage closed-loop adjustment link includes: a differential adjustment link, a delay link, a dead zone link, a first series correction link, a second series correction link, an amplification link and an amplitude limit link, and the wind power is adjusted through the voltage closed-loop adjustment link. Calculate the reactive current reference value of the inverter of the unit, and determine the compensation coefficient of the voltage closed-loop adjustment link;

According to the compensation coefficient of the voltage closed-loop adjustment link, the distribution of the reactive current among the wind turbines is adjusted to avoid the occurrence of reactive power grabbing or reactive power circulation among the wind turbines.

Preferably, the error adjustment link includes:

为附加补偿因数角，U_c为经过补偿后的风电机组逆变器并网点电压。where V _t is the grid-connected voltage of the wind turbine inverter, I _t is the grid-connected current of the wind turbine inverter, X _c is the additional compensation reactance,

is the additional compensation factor angle, and U _c is the voltage at the grid connection point of the wind turbine inverter after compensation.

Preferably, the delay link includes:

Among them, S is the complex frequency, and T _r is the time constant of the delay link.

Preferably, the calculation methods of the upper limit I _qimax and the lower limit I _qimin of the reactive current reference value of the limiting link are:

Among them, the current instantaneous active current of the ith wind turbine is _Itdi , and I _N is the rated current of the inverter of the ith wind turbine.

Preferably, the determining the compensation coefficient of the voltage closed-loop adjustment link further includes:

The calculation method of the compensation coefficient of the fast voltage closed-loop regulation link of the i-th wind turbine is:

δ _i =δ _i1 +δ _i2

Among them, δ _i1 is the natural compensation coefficient of the box-type transformer connected to the inverter of the ith wind turbine, δ _i2 is the additional compensation coefficient of the inverter of the ith wind turbine; δ _i is the inverse of the ith wind turbine The compensation coefficient of the voltage closed-loop regulation link of the inverter;

The formula for calculating the voltage drop of the box-type transformer in the wind turbine is:

Among them, R _T and X _T are the equivalent resistance and equivalent reactance of the high-voltage side of the box-type transformer, respectively, P _T and Q _T are the active power and reactive power flowing through the high-voltage side of the box-type transformer, respectively, and U _T is the box-type transformer. The terminal voltage of the high-voltage side;

When the rated value of the wind turbine is selected as the reference value, assuming that each physical quantity flowing through the box-type transformer is the rated value of the inverter, the calculation method of the natural compensation coefficient δ _i1 of the box-type transformer connected to the i-th wind turbine is as follows: :

为箱式变压器高压侧的机端电压标幺值，

为流过箱式变压器高压侧有功功率标幺值，

为箱式变压器高压侧的等效电阻标幺值，

为流过箱式变压器高压侧无功功率的标幺值，

为箱式变压器高压侧的等效电抗标幺值，

为箱式变压器高压侧的额定电压标幺值；

is the per-unit value of the terminal voltage of the high-voltage side of the box-type transformer,

is the per-unit value of active power flowing through the high-voltage side of the box-type transformer,

is the equivalent resistance per unit value of the high-voltage side of the box-type transformer,

is the per-unit value of reactive power flowing through the high-voltage side of the box-type transformer,

is the equivalent reactance per unit value of the high-voltage side of the box-type transformer,

is the rated voltage per unit value of the high-voltage side of the box-type transformer;

The calculation method of the additional compensation coefficient of the fast voltage closed-loop regulation link of the ith wind turbine inverter is:

为第i台风电机组的附加补偿因数角，通过对每台风电机组设置不同的附加补偿电抗和附加补偿因数角，实现无功电流在各风电机组之间的合理分配。Among them, Xci is the additional compensation reactance of the i-th wind turbine,

For the additional compensation factor angle of the i-th wind turbine, by setting different additional compensation reactance and additional compensation factor angle for each wind turbine, the rational distribution of reactive current among each wind turbine is realized.

Preferably, when the voltage at the grid-connected point deviates from the reference value and exceeds the dead zone, the smaller the compensation coefficient setting value, the larger the reference value of reactive current allocated by the wind turbine.

Preferably, the principle of setting the compensation coefficient of each wind turbine is that the larger the adjustable range of reactive power, the smaller the compensation coefficient, and there are:

Among them, I _tqimax is the maximum value of the reactive current of the wind turbine inverter, and the compensation coefficient δ _i is set to a number close to zero or close to infinity.

Based on another aspect of the present invention, a fast voltage response control system for closed-loop regulation of wind turbine generator terminal voltage is provided, the system comprising:

The initial unit is used to connect the voltage closed-loop regulation link based on the fast voltage response control link in series in the current control link of the wind turbine inverter;

A determination unit, used for the voltage closed-loop adjustment link including: a differential adjustment link, a delay link, a dead zone link, a first series correction link, a second series correction link, an amplification link and an amplitude limit link, through the voltage closed-loop adjustment The link calculates the reactive current reference value of the wind turbine inverter, and determines the compensation coefficient of the voltage closed-loop adjustment link;

The adjustment unit is configured to adjust the distribution of the reactive current among the wind turbines according to the compensation coefficient of the voltage closed-loop adjustment link, so as to avoid the occurrence of reactive power grabbing or reactive power circulation among the wind turbines.

Preferably, the error adjustment link includes:

为附加补偿因数角，U_c为经过补偿后的风电机组逆变器并网点电压。where V _t is the grid-connected voltage of the wind turbine inverter, I _t is the grid-connected current of the wind turbine inverter, X _c is the additional compensation reactance,

is the additional compensation factor angle, and U _c is the voltage at the grid connection point of the wind turbine inverter after compensation.

Preferably, the delay link includes:

Among them, S is the complex frequency, and T _r is the time constant of the delay link.

Preferably, the calculation methods of the upper limit I _qimax and the lower limit I _qimin of the reactive current reference value of the limiting link are:

Among them, the current instantaneous active current of the ith wind turbine is _Itdi , and I _N is the rated current of the inverter of the ith wind turbine.

Preferably, the determining the compensation coefficient of the voltage closed-loop adjustment link further includes:

The calculation method of the compensation coefficient of the fast voltage closed-loop regulation link of the i-th wind turbine is:

δ _i =δ _i1 +δ _i2

Among them, δ _i1 is the natural compensation coefficient of the box-type transformer connected to the inverter of the ith wind turbine, δ _i2 is the additional compensation coefficient of the inverter of the ith wind turbine; δ _i is the inverse of the ith wind turbine The compensation coefficient of the voltage closed-loop regulation link of the inverter;

The formula for calculating the voltage drop of the box-type transformer in the wind turbine is:

Among them, R _T and X _T are the equivalent resistance and equivalent reactance of the high-voltage side of the box-type transformer, respectively, P _T and Q _T are the active power and reactive power flowing through the high-voltage side of the box-type transformer, respectively, and U _T is the box-type transformer. The terminal voltage of the high-voltage side;

When the rated value of the wind turbine is selected as the reference value, assuming that each physical quantity flowing through the box-type transformer is the rated value of the inverter, the calculation method of the natural compensation coefficient δ _i1 of the box-type transformer connected to the i-th wind turbine is as follows: :

为箱式变压器高压侧的机端电压标幺值，

为流过箱式变压器高压侧有功功率标幺值，

为箱式变压器高压侧的等效电阻标幺值，

为流过箱式变压器高压侧无功功率的标幺值，

为箱式变压器高压侧的等效电抗标幺值，

为箱式变压器高压侧的额定电压标幺值；

is the per-unit value of the terminal voltage of the high-voltage side of the box-type transformer,

is the per-unit value of active power flowing through the high-voltage side of the box-type transformer,

is the equivalent resistance per unit value of the high-voltage side of the box-type transformer,

is the per-unit value of reactive power flowing through the high-voltage side of the box-type transformer,

is the equivalent reactance per unit value of the high-voltage side of the box-type transformer,

is the rated voltage per unit value of the high-voltage side of the box-type transformer;

The calculation method of the additional compensation coefficient of the fast voltage closed-loop regulation link of the ith wind turbine inverter is:

为第i台风电机组的附加补偿因数角，通过对每台风电机组设置不同的附加补偿电抗和附加补偿因数角，实现无功电流在各风电机组之间的合理分配。Among them, Xci is the additional compensation reactance of the i-th wind turbine,

For the additional compensation factor angle of the i-th wind turbine, by setting different additional compensation reactance and additional compensation factor angle for each wind turbine, the rational distribution of reactive current among each wind turbine is realized.

Preferably, when the voltage at the grid-connected point deviates from the reference value and exceeds the dead zone, the smaller the compensation coefficient setting value, the larger the reference value of reactive current allocated by the wind turbine.

Preferably, the principle of setting the compensation coefficient of each wind turbine is that the larger the adjustable range of reactive power, the smaller the compensation coefficient, and there are:

Among them, I _tqimax is the maximum value of the reactive current of the wind turbine inverter, and the compensation system

The number δ _i is set to a number close to zero or close to infinity.

The technical scheme of the present invention provides a fast voltage response control method for closed-loop regulation of the wind turbine generator terminal voltage. The closed-loop adjustment links include: the difference adjustment link, the delay link, the dead zone link, the first series correction link, the second series correction link, the amplification link and the limit link. Calculate the current reference value, and determine the compensation coefficient of the voltage closed-loop regulation link; adjust the distribution of reactive current among the wind turbines according to the compensation coefficient of the voltage closed-loop regulation link, so as to avoid rushing reactive power or reactive power among the wind turbines The occurrence of circulation phenomenon. The technical solution of the present invention is to distribute the reactive current of each wind turbine by connecting the fast voltage response control link in series in the reactive power adjustment link of the wind turbine, and at the same time dynamically adjusting the reactive power compensation coefficient according to the adjustable capacity of the inverter, so as to distribute the reactive current of each wind turbine, and suppress the The reactive power circulation between the wind turbines compensates the reactive power consumed by the box transformer and improves the voltage stability of the wind farm operation.

Description of drawings

Exemplary embodiments of the present invention may be more fully understood by reference to the following drawings:

Fig. 1 is a flow chart of a fast voltage response control method for closed-loop regulation of wind turbine generator terminal voltage according to a preferred embodiment of the present invention;

FIG. 2 is a system structure diagram of a typical wind farm connection structure diagram according to a preferred embodiment of the present invention;

Fig. 3 is a flow chart of calculating a reactive current reference value of a wind turbine inverter according to a preferred embodiment of the present invention;

4 is a schematic diagram of a method for determining upper and lower limits of a reactive current reference value according to a preferred embodiment of the present invention;

5 is a schematic diagram of an equivalent circuit of a box-type transformer according to a preferred embodiment of the present invention;

FIG. 6 is a schematic diagram of a grid-connected point voltage-reactive current curve after adding a fast voltage response control link in the voltage closed-loop regulation according to a preferred embodiment of the present invention; and

FIG. 7 is a structural diagram of a fast voltage response control system for closed-loop regulation of wind turbine generator terminal voltage according to a preferred embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for the purpose of this thorough and complete disclosure invention, and fully convey the scope of the invention to those skilled in the art. The terms used in the exemplary embodiments shown in the drawings are not intended to limit the invention. In the drawings, the same elements/elements are given the same reference numerals.

Unless otherwise defined, terms (including scientific and technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is to be understood that terms defined in commonly used dictionaries should be construed as having meanings consistent with the context in the related art, and should not be construed as idealized or overly formal meanings.

FIG. 1 is a flowchart of a fast voltage response control method for closed-loop regulation of wind turbine generator terminal voltage according to a preferred embodiment of the present invention. As shown in Figure 1, a fast voltage response control method for closed-loop regulation of wind turbine generator terminal voltage, the method includes:

Preferably, in step 101: in the current control link of the wind turbine inverter, a voltage closed-loop regulation link based on the fast voltage response control link is connected in series;

Preferably, in step 102: the voltage closed-loop adjustment link includes: a differential adjustment link, a delay link, a dead zone link, a first series correction link, a second series correction link, an amplification link and an amplitude limit link. Calculate the reactive current reference value of the wind turbine inverter, and determine the compensation coefficient of the voltage closed-loop regulation link;

Preferably, in step 103: according to the compensation coefficient of the voltage closed-loop adjustment link, the distribution of reactive current among the wind turbines is adjusted to avoid the occurrence of reactive power grabbing or reactive power circulation among the wind turbines.

Preferably, the error adjustment link includes:

为附加补偿因数角，U_c为经过补偿后的风电机组逆变器并网点电压。where V _t is the grid-connected voltage of the wind turbine inverter, I _t is the grid-connected current of the wind turbine inverter, X _c is the additional compensation reactance,

is the additional compensation factor angle, and U _c is the voltage at the grid connection point of the wind turbine inverter after compensation.

Preferably, the delay link includes:

Among them, S is the complex frequency, and T _r is the time constant of the delay link.

Preferably, the calculation methods of the upper limit I _qimax and the lower limit I _qimin of the reactive current reference value of the limiting link are:

Among them, the current instantaneous active current of the ith wind turbine is _Itdi , and I _N is the rated current of the inverter of the ith wind turbine.

Preferably, determining the compensation coefficient of the voltage closed-loop adjustment link further includes:

The calculation method of the compensation coefficient of the fast voltage closed-loop regulation link of the i-th wind turbine is:

δ _i =δ _i1 +δ _i2

Among them, δ _i1 is the natural compensation coefficient of the box-type transformer connected to the inverter of the ith wind turbine, δ _i2 is the additional compensation coefficient of the inverter of the ith wind turbine; δ _i is the inverse of the ith wind turbine The compensation coefficient of the voltage closed-loop regulation link of the inverter;

The formula for calculating the voltage drop of the box-type transformer in the wind turbine is:

Among them, R _T and X _T are the equivalent resistance and equivalent reactance of the high-voltage side of the box-type transformer, respectively, P _T and Q _T are the active power and reactive power flowing through the high-voltage side of the box-type transformer, respectively, and U _T is the box-type transformer. The terminal voltage of the high-voltage side;

When the rated value of the wind turbine is selected as the reference value, assuming that each physical quantity flowing through the box-type transformer is the rated value of the inverter, the calculation method of the natural compensation coefficient δ _i1 of the box-type transformer connected to the i-th wind turbine is as follows: :

为箱式变压器高压侧的机端电压标幺值，

为流过箱式变压器高压侧有功功率标幺值，

为箱式变压器高压侧的等效电阻标幺值，

为流过箱式变压器高压侧无功功率的标幺值，

为箱式变压器高压侧的等效电抗标幺值，

为箱式变压器高压侧的额定电压标幺值；

is the per-unit value of the terminal voltage of the high-voltage side of the box-type transformer,

is the per-unit value of active power flowing through the high-voltage side of the box-type transformer,

is the equivalent resistance per unit value of the high-voltage side of the box-type transformer,

is the per-unit value of reactive power flowing through the high-voltage side of the box-type transformer,

is the equivalent reactance per unit value of the high-voltage side of the box-type transformer,

is the rated voltage per unit value of the high-voltage side of the box-type transformer;

The calculation method of the additional compensation coefficient of the fast voltage closed-loop regulation link of the ith wind turbine inverter is:

为第i台风电机组的附加补偿因数角，通过对每台风电机组设置不同的附加补偿电抗和附加补偿因数角，实现无功电流在各风电机组之间的合理分配。Among them, Xci is the additional compensation reactance of the i-th wind turbine,

For the additional compensation factor angle of the i-th wind turbine, by setting different additional compensation reactance and additional compensation factor angle for each wind turbine, the rational distribution of reactive current among each wind turbine is realized.

Preferably, when the voltage at the grid-connected point deviates from the reference value and exceeds the dead zone, the smaller the compensation coefficient setting value, the larger the reference value of reactive current allocated by the wind turbine.

Preferably, the principle of setting the compensation coefficient of each wind turbine is that the larger the adjustable range of reactive power, the smaller the compensation coefficient, and there are:

Among them, I _tqimax is the maximum value of the reactive current of the wind turbine inverter, and the compensation coefficient δ _i is set to a number close to zero or close to infinity.

The following examples illustrate the embodiments of the present application:

(1) In the q-axis current control link of the wind turbine inverter, the voltage closed-loop regulation link based on the fast voltage response control link is connected in series. as shown in picture 2.

为附加补偿因数角，U_c为经过补偿后的风电机组逆变器并网点电压，T₁和T₂分别为第一串联校正环节的时间常数，T₃和T₄分别为第二串联校正环节时间常数，K为串联校正环节的直流增益，K_v为积分校正环节选择因子，K_v＝0时为纯积分校正，K_v＝1时为比例积分校正，K_a为放大环节增益，Ta为放大环节时间常数，I_qimax和I_qimin分别为无功电流参考值的上下限。(2) A fast voltage response control method for closed-loop regulation of wind turbine generator terminal voltage includes a fast voltage response control link, a delay link, a dead zone link, a first series correction link, a second series correction link and an amplification link, such as As shown in Figure 3, where V _t is the grid-connected voltage of the wind turbine inverter, I _t is the grid-connected current of the wind turbine inverter, X _c is the additional compensation reactance,

is the additional compensation factor angle, U _c is the grid-connected point voltage of the wind turbine inverter after compensation, T ₁ and T ₂ are the time constants of the first series correction link, respectively, T ₃ and T ₄ are the second series correction link, respectively Time constant, K is the DC gain of the series correction link, K _v is the selection factor of the integral correction link, when K _v =0 is pure integral correction, when K _{v =} 1 is proportional integral correction, Ka is the gain of the amplification link, and Ta is Amplification link time constant, I _qimax and I _qimin are the upper and lower limits of the reactive current reference value, respectively.

(3) The method for determining the upper and lower limits I _qimax and I _qimin of the reactive current reference value is shown in Figure 4. Assuming that the current instantaneous active current of the i-th wind turbine is I _dti , the upper and lower limits of the reactive current I _qimax and I _qimin Determined by formula (1) and formula (2);

(4) The equivalent circuit of the box-type transformer of the wind turbine is shown in Figure 5, where R _T and X _T are the equivalent resistance and equivalent reactance of the high-voltage side of the box-type transformer, respectively, and G _T and B _T are the high-voltage side of the box-type transformer, respectively. The equivalent conductance and equivalent susceptance of the side, P _T and Q _T are the active power and reactive power flowing through the high-voltage side of the box-type transformer, respectively.

(5) The calculation method of the compensation coefficient of the voltage closed-loop regulation link of the ith wind turbine inverter is as follows:

δ _i =δ _i1 +δ _i2 (3)

Among them, δ _i1 is the natural compensation coefficient of the box-type transformer connected to the ith wind turbine inverter, and δ _i2 is the additional compensation coefficient of the ith wind turbine inverter.

(6) For wind turbines, the formula for calculating the voltage drop of the box-type transformer is:

(7) When the rated value of the wind turbine is selected as the reference value, assuming that each physical quantity flowing through the box-type transformer is the rated value of the inverter, the natural compensation coefficient δ _i1 of the box-type transformer connected to the i-th wind turbine The calculation method is

(8) The calculation method of the additional compensation coefficient of the fast voltage response control link of the inverter of the i-th wind turbine is as follows:

为第i台风电机组的附加补偿因数角，通过对每台风电机组设置不同的附加补偿电抗和附加补偿因数角，可以实现无功电流在各风电机组之间的合理分配。Among them, X _ci is the additional compensation reactance of the i-th wind turbine,

For the additional compensation factor angle of the i-th wind turbine, by setting different additional compensation reactance and additional compensation factor angle for each wind turbine, the rational distribution of reactive current among each wind turbine can be realized.

(9) When the voltage at the grid-connected point deviates from the reference value and exceeds the dead zone, the reference value of reactive current allocated to wind turbines with different compensation coefficients is shown in Figure 6. the larger the value.

(10) In order to realize the reasonable distribution of reactive current among the wind turbines, and not cause the phenomenon of reactive power grabbing or reactive power circulation, the conditions for the compensation coefficient of each wind turbine to be satisfied are:

δ _i > 0 (7)

(11) The principle of setting the compensation coefficient of each wind turbine is that the larger the adjustable range of reactive power, the smaller the compensation coefficient, and there are

However, in the actual setting, δ _i cannot be set to 0 or positive infinity, but can be set to a number close to zero or a relatively large number.

In the embodiment of the present application, the fast voltage response control link is connected in series in the reactive power adjustment link of the wind turbine, and the reactive power compensation coefficient is dynamically adjusted according to the adjustable capacity of the inverter, so as to distribute the reactive current of each wind turbine, and at the same time suppress the wind turbine. It can compensate the reactive power consumed by the box transformer and improve the voltage stability of the wind farm operation.

FIG. 7 is a structural diagram of a fast voltage response control system for closed-loop regulation of wind turbine generator terminal voltage according to a preferred embodiment of the present invention. As shown in Figure 7, a fast voltage response control system for closed-loop regulation of wind turbine generator terminal voltage, the system includes:

The initial unit 701 is used to connect the voltage closed-loop regulation link based on the fast voltage response control link in series in the current control link of the wind turbine inverter.

The determination unit 702 is used for the voltage closed-loop adjustment link including: a differential adjustment link, a delay link, a dead zone link, a first series correction link, a second series correction link, an amplification link and an amplitude limit link. The reactive current reference value of the inverter of the unit is calculated, and the compensation coefficient of the voltage closed-loop regulation link is determined.

The adjustment unit 703 is configured to adjust the distribution of reactive current among the wind turbines according to the compensation coefficient of the voltage closed-loop adjustment link, so as to avoid the occurrence of reactive power grabbing or reactive power circulation among the wind turbines.

Preferably, the error adjustment link includes:

为附加补偿因数角，U_c为经过补偿后的风电机组逆变器并网点电压。where V _t is the grid-connected voltage of the wind turbine inverter, I _t is the grid-connected current of the wind turbine inverter, X _c is the additional compensation reactance,

is the additional compensation factor angle, and U _c is the voltage at the grid connection point of the wind turbine inverter after compensation.

Preferably, the delay link includes:

Among them, S is the complex frequency, and T _r is the time constant of the delay link.

Preferably, the calculation methods of the upper limit I _qimax and the lower limit I _qimin of the reactive current reference value of the limiting link are:

Among them, the current instantaneous active current of the ith wind turbine is _Itdi , and I _N is the rated current of the inverter of the ith wind turbine.

Preferably, determining the compensation coefficient of the voltage closed-loop adjustment link further includes:

The calculation method of the compensation coefficient of the fast voltage closed-loop regulation link of the i-th wind turbine is:

δ _i =δ _i1 +δ _i2

Among them, δ _i1 is the natural compensation coefficient of the box-type transformer connected to the inverter of the ith wind turbine, δ _i2 is the additional compensation coefficient of the inverter of the ith wind turbine; δ _i is the inverse of the ith wind turbine The compensation coefficient of the voltage closed-loop regulation link of the inverter;

The formula for calculating the voltage drop of the box-type transformer in the wind turbine is:

Among them, R _T and X _T are the equivalent resistance and equivalent reactance of the high-voltage side of the box-type transformer, respectively, P _T and Q _T are the active power and reactive power flowing through the high-voltage side of the box-type transformer, respectively, and U _T is the box-type transformer. The terminal voltage of the high-voltage side;

When the rated value of the wind turbine is selected as the reference value, assuming that each physical quantity flowing through the box-type transformer is the rated value of the inverter, the calculation method of the natural compensation coefficient δ _i1 of the box-type transformer connected to the i-th wind turbine is as follows: :

为箱式变压器高压侧的机端电压标幺值，

为流过箱式变压器高压侧有功功率标幺值，

为箱式变压器高压侧的等效电阻标幺值，

为流过箱式变压器高压侧无功功率的标幺值，

为箱式变压器高压侧的等效电抗标幺值，

为箱式变压器高压侧的额定电压标幺值；

is the per-unit value of the terminal voltage of the high-voltage side of the box-type transformer,

is the per-unit value of active power flowing through the high-voltage side of the box-type transformer,

is the equivalent resistance per unit value of the high-voltage side of the box-type transformer,

is the per-unit value of reactive power flowing through the high-voltage side of the box-type transformer,

is the equivalent reactance per unit value of the high-voltage side of the box-type transformer,

is the rated voltage per unit value of the high-voltage side of the box-type transformer;

The calculation method of the additional compensation coefficient of the fast voltage closed-loop regulation link of the ith wind turbine inverter is:

为第i台风电机组的附加补偿因数角，通过对每台风电机组设置不同的附加补偿电抗和附加补偿因数角，实现无功电流在各风电机组之间的合理分配。Among them, Xci is the additional compensation reactance of the i-th wind turbine,

For the additional compensation factor angle of the i-th wind turbine, by setting different additional compensation reactance and additional compensation factor angle for each wind turbine, the rational distribution of reactive current among each wind turbine is realized.

Preferably, when the voltage at the grid-connected point deviates from the reference value and exceeds the dead zone, the smaller the compensation coefficient setting value, the larger the reference value of reactive current allocated by the wind turbine.

Preferably, the principle of setting the compensation coefficient of each wind turbine is that the larger the adjustable range of reactive power, the smaller the compensation coefficient, and there are:

Among them, I _tqimax is the maximum value of the reactive current of the wind turbine inverter, and the compensation coefficient δ _i is set to a number close to zero or close to infinity.

A preferred embodiment of the present invention, a fast voltage response control system 700 for closed-loop regulation of wind turbine generator terminal voltage corresponds to another preferred embodiment of the present invention, a fast voltage response control method 100 for wind turbine generator terminal voltage closed-loop regulation, No further description is given here.

The present invention has been described with reference to a few embodiments. However, as is known to those skilled in the art, other embodiments than the above disclosed invention are equally within the scope of the invention, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/the/the [means, component, etc.]" are open to interpretation as at least one instance of said means, component, etc., unless expressly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (8)

1. A control method for closed-loop regulation of wind turbine generator terminal voltage, wherein the method comprises: In the current control link of the wind turbine inverter, a voltage closed-loop adjustment link based on the fast voltage response control link is connected in series; the voltage closed-loop adjustment link includes: a differential adjustment link, a delay link, a dead zone link, a first series correction link, The second series correction link, amplification link and clipping link; Calculate the reactive current reference value of the wind turbine inverter through the voltage closed-loop adjustment link, and determine the compensation coefficient of the voltage closed-loop adjustment link, further comprising: The calculation method of the compensation coefficient of the fast voltage closed-loop regulation link of the i-th wind turbine is: δ _i =δ _i1 +δ _i2 Among them, δ _i1 is the natural compensation coefficient of the box-type transformer connected to the inverter of the ith wind turbine, δ _i2 is the additional compensation coefficient of the inverter of the ith wind turbine; δ _i is the inverse of the ith wind turbine The compensation coefficient of the voltage closed-loop regulation link of the inverter; The formula for calculating the voltage drop of the box-type transformer in the wind turbine is:

Among them, R _T and X _T are the equivalent resistance and equivalent reactance of the high-voltage side of the box-type transformer, respectively, P _T and Q _T are the active power and reactive power flowing through the high-voltage side of the box-type transformer, respectively, and U _T is the box-type transformer. The terminal voltage of the high-voltage side; When the rated value of the wind turbine is selected as the reference value, assuming that each physical quantity flowing through the box-type transformer is the rated value of the inverter, the calculation method of the natural compensation coefficient δ _i1 of the box-type transformer connected to the i-th wind turbine is as follows: :

is the per-unit value of the terminal voltage of the high-voltage side of the box-type transformer,

is the per-unit value of active power flowing through the high-voltage side of the box-type transformer,

is the equivalent resistance per unit value of the high-voltage side of the box-type transformer,

is the per-unit value of reactive power flowing through the high-voltage side of the box-type transformer,

is the equivalent reactance per unit value of the high-voltage side of the box-type transformer,

is the rated voltage per unit value of the high-voltage side of the box-type transformer; The calculation method of the additional compensation coefficient of the fast voltage closed-loop regulation link of the ith wind turbine inverter is:

Among them, X _ci is the additional compensation reactance of the i-th wind turbine,

For the additional compensation factor angle of the i-th wind turbine, by setting different additional compensation reactance and additional compensation factor angle for each wind turbine, the rational distribution of reactive current among each wind turbine is realized; When the voltage of the grid-connected point deviates from the reference value and exceeds the dead zone, the smaller the compensation coefficient setting value is, the larger the reference value of reactive current allocated by the wind turbine; The principle of setting the compensation coefficient of each wind turbine is that the larger the adjustable range of reactive power, the smaller the compensation coefficient, and there are:

Among them, I _tqimax is the maximum value of the reactive current of the wind turbine inverter, and the compensation coefficient δ _i is set to a number close to zero or close to infinity; According to the compensation coefficient of the voltage closed-loop adjustment link, the distribution of the reactive current among the wind turbines is adjusted to avoid the occurrence of reactive power grabbing or reactive power circulation among the wind turbines. 2. The method according to claim 1, wherein the step of adjusting the difference comprises:

where V _t is the grid-connected voltage of the wind turbine inverter, I _t is the grid-connected current of the wind turbine inverter, X _c is the additional compensation reactance,

is the additional compensation factor angle, and U _c is the voltage at the grid connection point of the wind turbine inverter after compensation. 3. The method according to claim 1, wherein the delay link comprises:

Among them, S is the complex frequency, and T _r is the time constant of the delay link. 4. The method according to claim 1, wherein the calculation method of the upper limit I _qimax and the lower limit I _qimin of the reactive current reference value of the limiter link is:

Among them, the current instantaneous active current of the ith wind turbine is _Itdi , and I _N is the rated current of the inverter of the ith wind turbine. 5. A control system for closed-loop regulation of wind turbine generator terminal voltage, characterized in that the system comprises: The initial unit is used to connect the voltage closed-loop regulation link based on the fast voltage response control link in series in the current control link of the wind turbine inverter; a determination unit, configured to calculate the reactive current reference value of the wind turbine inverter through the voltage closed-loop adjustment link, and determine the compensation coefficient of the voltage closed-loop adjustment link; determining the voltage closed-loop adjustment link The compensation factor of , also includes: The calculation method of the compensation coefficient of the fast voltage closed-loop regulation link of the i-th wind turbine is: δ _i =δ _i1 +δ _i2 Among them, δ _i1 is the natural compensation coefficient of the box-type transformer connected to the inverter of the ith wind turbine, δ _i2 is the additional compensation coefficient of the inverter of the ith wind turbine; δ _i is the inverse of the ith wind turbine The compensation coefficient of the voltage closed-loop regulation link of the inverter; The formula for calculating the voltage drop of the box-type transformer in the wind turbine is:

Among them, R _T and X _T are the equivalent resistance and equivalent reactance of the high-voltage side of the box-type transformer, respectively, P _T and Q _T are the active power and reactive power flowing through the high-voltage side of the box-type transformer, respectively, and U _T is the box-type transformer. The terminal voltage of the high-voltage side; When the rated value of the wind turbine is selected as the reference value, assuming that each physical quantity flowing through the box-type transformer is the rated value of the inverter, the calculation method of the natural compensation coefficient δ _i1 of the box-type transformer connected to the i-th wind turbine is as follows: :

is the per-unit value of the terminal voltage of the high-voltage side of the box-type transformer,

is the per-unit value of active power flowing through the high-voltage side of the box-type transformer,

is the equivalent resistance per unit value of the high-voltage side of the box-type transformer,

is the per-unit value of reactive power flowing through the high-voltage side of the box-type transformer,

is the equivalent reactance per unit value of the high-voltage side of the box-type transformer,

is the rated voltage per unit value of the high-voltage side of the box-type transformer; The calculation method of the additional compensation coefficient of the fast voltage closed-loop regulation link of the ith wind turbine inverter is:

Among them, X _ci is the additional compensation reactance of the i-th wind turbine,

For the additional compensation factor angle of the i-th wind turbine, by setting different additional compensation reactance and additional compensation factor angle for each wind turbine, the rational distribution of reactive current among each wind turbine is realized; When the voltage of the grid-connected point deviates from the reference value and exceeds the dead zone, the smaller the compensation coefficient setting value is, the larger the reference value of reactive current allocated by the wind turbine; The principle of setting the compensation coefficient of each wind turbine is that the larger the adjustable range of reactive power, the smaller the compensation coefficient, and there are:

Among them, I _tqimax is the maximum value of the reactive current of the wind turbine inverter, and the compensation coefficient δ _i is set to a number close to zero or close to infinity; The voltage closed-loop adjustment link includes: a difference adjustment link, a delay link, a dead zone link, a first series correction link, a second series correction link, an amplification link and an amplitude limit link; The adjustment unit is configured to adjust the distribution of the reactive current among the wind turbines according to the compensation coefficient of the voltage closed-loop adjustment link, so as to avoid the occurrence of reactive power grabbing or reactive power circulation among the wind turbines. 6. The system according to claim 5, wherein the error adjustment link comprises:

where V _t is the grid-connected voltage of the wind turbine inverter, I _t is the grid-connected current of the wind turbine inverter, X _c is the additional compensation reactance,

is the additional compensation factor angle, and U _c is the voltage at the grid connection point of the wind turbine inverter after compensation. 7. The system according to claim 5, wherein the delay link comprises:

Among them, S is the complex frequency, and T _r is the time constant of the delay link. 8. The system according to claim 5, wherein the calculation method of the upper limit I _qimax and the lower limit I _qimin of the reactive current reference value of the limiter link is:

Among them, the current instantaneous active current of the ith wind turbine is _Itdi , and I _N is the rated current of the inverter of the ith wind turbine.

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