CN110137941B - Power grid stability control method and device based on double-fed fan stability influence - Google Patents

Abstract

The invention discloses a power grid stability control method and device based on the influence of the stability of a doubly-fed wind turbine. The method includes: collecting operating parameters of the doubly-fed wind turbine; calculating and obtaining a forward direction according to the operating parameters and a preset model. The channel transfer function and the transfer function of the doubly-fed fan; calculate the damping torque of the electromechanical oscillation circuit of the synchronous machine when a single doubly-fed fan is connected to the multi-machine power system; according to the damping torque, calculate the The sensitivity of the damping coefficient of the generator; according to the damping torque and the sensitivity of the damping coefficient, the influence value of the single DFIG on the stability of the multi-machine power system is calculated; Compared with the traditional eigenvalue method, the analysis of the influence of the feeder on the stability of the power system has a clearer physical meaning, which can more clearly show the action path of the electromechanical oscillation circuit, and at the same time greatly reduce the calculation pressure and facilitate engineering applications.

Description

A grid stability control method and device based on the influence of double-fed wind turbine stability

technical field

The invention relates to the field of analysis of the stability of new energy power systems, and more specifically, to a method and device for controlling the stability of a power grid based on the influence of the stability of a doubly-fed fan.

Background technique

With the increase of wind power grid-connected capacity, the impact of wind farms on system stability is increasing, and the impact of wind power access on low-frequency oscillations in power systems has attracted much attention. In the current existing research, most of the traditional mode analysis methods are used to judge the impact of wind turbine access on the small disturbance stability of the power system by calculating the change in the oscillation mode of the power system before and after the wind turbine is connected to the grid.

Most of the existing research is to analyze different examples, and then use time domain simulation to verify. This research method can only provide result data such as stability changes, but it cannot reflect the root cause of the wind power grid-connected influence on the low-frequency oscillation of the power system; moreover, the conclusions drawn by this research method are heavily dependent on the example system, and different systems get The results are not the same, even contradictory. It can be seen that in the current research on the stability of wind power grid connection, the lack of more in-depth research methods is also one of the main reasons for limiting the research progress in this field.

Among the various analysis methods for low-frequency oscillations in power systems, the theory of damping torque analysis is relatively complete, and its physical meaning is relatively clear, which can clearly show the action path of the controller on the electromechanical oscillation circuit. The application of the damping torque torque method on the influence of power electronic equipment on the grid is also increasing.

In addition, when multiple wind turbines are connected to the grid at the same time, the interaction between multiple wind turbines will also have a certain impact on the dynamic stability of the power system. Compared with the grid connection of single wind turbines, the total impact caused by multiple wind turbines may make the system more stable, or it may make the system more unstable. In the damping control analysis of the power system, not only the total influence of multiple damping controllers needs to be known, but also whether each damping controller can play its role to the greatest extent is also a concern. optimal configuration. How to maximize the efficiency of both controllers to produce "1+1≈2" or even "1+1>2" is the goal pursued in damping control.

Contents of the invention

In order to solve the problem that the traditional analysis method existing in the background technology cannot reflect the root cause of the wind power grid-connected influence on the low-frequency oscillation of the power system and the conclusion drawn by the research method is heavily dependent on the example system, the present invention provides a double-fed wind turbine based A method for controlling stability of a power grid affected by stability, the method comprising:

Collecting the operating parameters of the doubly-fed fan; the operating parameters include machine terminal voltage, output current, active power and reactive power;

According to the operating parameters and the preset model, calculate and obtain the transfer function of the forward channel and the transfer function of the double-fed fan; the transfer function of the forward channel is the transfer function from the output power of the double-fed fan to the electromagnetic torque; the double-fed fan The transfer function of the fan feeder is the transfer function from the fan terminal voltage to the output power of the fan;

According to the transfer function of the forward channel, the transfer function of the double-fed fan and the angular velocity of the synchronous machine, the damping torque of the electromechanical oscillation circuit of the synchronous machine to a single double-fed fan connected to the multi-machine power system is calculated;

calculating the sensitivity to the damping coefficient of the synchronous machine in different oscillation modes according to the damping torque;

Calculate the influence value of the single double-fed fan on the stability of the multi-machine power system according to the damping torque and the sensitivity of the damping coefficient;

Pre-warning control is performed on the power grid according to the influence value and a preset pre-warning threshold.

Further, before performing early warning control on the power grid according to the influence value and the preset warning threshold, the method further includes: according to the influence value of the single double-fed wind turbine on the stability of the multi-machine power system, , calculating the dynamic interaction between multiple double-fed wind turbines on the stability of the multi-machine power system.

Further, the formula for calculating the forward channel transfer function is:

Among them, ΔT _e is the electromagnetic torque, ΔPQ ₁ is the output power of the fan,

The matrices A and B are obtained from the state space model of the multi-machine power system part, and the state space model is:

Among them, ΔV _s is the terminal voltage of the DFIG, ΔP _w and ΔQ _w are the output active and reactive power of the DFIG, respectively; X _g is the column vector composed of all state variables in the multi-machine power system;

When a single double-fed fan is connected to a multi-machine power system, the state space model is expanded as,

Among them, δ represents the column vector composed of the power angles of all synchronous machines, ω represents the column vector composed of the angular velocities of all synchronous machines, z represents the column vector composed of all other state variables in the multi-machine power system, ΔPQ ₁ =[ΔP ₁ ΔQ ₁ ] ^T ;

The formula for calculating the transfer function of the doubly-fed fan is,

The formula for converting the input variable of the double-fed fan into the transfer function of the angular velocity of the synchronous machine to form a column vector is,

Among them, Δω _k is the column vector composed of the angular velocity of the kth synchronous machine, λ _i is the ith eigenvalue of the open-loop A array in the expansion of the state space model, v _i is the right eigenvector corresponding to λ _i , v _ik is the value corresponding to Δω _k in v _i .

Further, the formula for calculating the damping torque of a single doubly-fed fan connected to a multi-machine power system to the electromechanical oscillation circuit of a synchronous machine is:

ΔT _1Dk = D _1k Δω _k

Among them, D _1k ＝Re[F _k (λ _i )G _k (λ _i )γ _ik ], said D _1k ＝Re[F _k (λ _i )G _k (λ _i )γ _ik ] is paired by double-fed fan The electromagnetic torque of the electromechanical oscillating circuit of K synchronous machine is obtained, and the formula of described electromagnetic torque is,

Wherein, the K is a positive integer.

Further, according to the damping torque, the formula for calculating the sensitivity to the damping coefficient of the synchronous machine in different oscillation modes is:

Among them, S _ik is the sensitivity of the i-th oscillation mode to the damping coefficient of the k-th synchronous machine.

Further, according to the damping torque and the sensitivity of the damping coefficient, the formula for calculating the influence value of the single double-fed fan on the stability of the multi-machine power system is:

Among them, _Δλi is the total influence value of the dynamic interaction between single wind turbine and multi-machine power system on the ith oscillation mode.

Further, according to the influence value of the single double-fed fan on the stability of the multi-machine power system, the formula for calculating the influence value of the dynamic interaction between any two double-fed fans on the stability of the power system is: :

Among them, _Δλi is the change in electromechanical oscillation mode of the power system caused by the addition of any second DFIG among the multiple DFIGs to the dynamic interaction of the first DFIG; ΔD _1k is the Describe the dynamic interaction of any second DFIG among multiple DFIGs, resulting in the change in the damping torque of the first DFIG.

The grid stability control device based on the stability influence of double-fed wind turbines includes:

A collection unit, the collection unit is used to collect the operating parameters of the doubly-fed fan; the operating parameters include machine terminal voltage, output current, active power and reactive power;

A transfer function calculation unit, the transfer function calculation unit is used to calculate and obtain the transfer function of the forward channel and the transfer function of the double-fed fan according to the operating parameters and the preset model; the transfer function of the forward channel is the transfer function of the double-fed fan A transfer function from output power to electromagnetic torque; the transfer function of the double-fed fan is a transfer function from fan terminal voltage to fan output power;

A damping torque calculation unit, the damping torque calculation unit is used to calculate the electromechanical effect of a single double-fed fan connected to a multi-machine power system on the synchronous machine according to the forward channel transfer function, the double-fed fan transfer function and the angular velocity of the synchronous machine. The damping torque of the oscillation circuit, and the damping torque result is sent to the damping coefficient sensitivity calculation unit and the influence value calculation unit of a single double-fed fan;

A damping coefficient sensitivity calculation unit, the damping coefficient sensitivity calculation unit is used to calculate the sensitivity to the damping coefficient of the synchronous machine in different oscillation modes according to the damping torque, and to calculate the sensitivity to the synchronous machine in the different oscillation modes The sensitivity of the damping coefficient of the machine is sent to the influence value calculation unit of a single double-fed fan;

The influence value calculation unit of a single double-fed fan is connected to the damping torque calculation unit and the damping coefficient sensitivity calculation unit at one end, and is used to calculate the damping torque and the sensitivity of the damping coefficient according to the damping torque The impact value of the single double-fed fan on the stability of the multi-machine power system;

An early warning control unit, configured to perform early warning control on the power grid according to the influence value and a preset early warning threshold.

Further, the device also includes:

Multiple double-fed fan influence value calculation units, one end of the multiple double-fed fan influence value calculation unit is connected to the damping torque calculation unit and the damping coefficient sensitivity calculation unit, and the other end is connected to the single The doubly-fed wind turbine influence value calculation unit is connected to calculate the influence value of the dynamic interaction between multiple doubly-fed wind turbines on the stability of the multi-machine power system.

Further, it is characterized in that the transfer function calculation unit also includes:

A forward channel transfer function calculation unit, one end of the forward channel transfer function calculation unit is connected to the damping torque calculation unit for calculating the transfer function result from the output power of the single doubly-fed fan to the electromagnetic torque, and sending the calculation result of the transfer function from the output power of the single doubly-fed fan to the electromagnetic torque to the damping torque calculation unit;

A doubly-fed fan transfer function calculation unit, one end of the doubly-fed fan transfer function calculation unit is connected to the damping torque calculation unit; the doubly-fed fan transfer function calculation unit is used to calculate the terminal voltage of the single doubly-fed fan to the transfer function result of the output power of the single doubly-fed fan, and send the transfer function result of the terminal voltage of the single doubly-fed fan to the output power of the single doubly-fed fan to the damping torque calculation unit;

The input variable reconstruction unit is connected to the damping torque calculation unit at one end of the input variable reconstruction unit; the input variable reconstruction unit is used to convert the input variable of the single double-fed fan into the synchronous machine Angular velocity constitutes the transfer function of the column vector, and the input variable of the single doubly-fed fan is converted into the result of the synchronous machine angular velocity forming the transfer function of the column vector and sent to the damping torque calculation unit.

The beneficial effects of the present invention are as follows: the technical scheme of the present invention provides a method and device for power grid stability control based on the influence of the stability of double-fed wind turbines. The sensitivity to the damping coefficient of the synchronous machine under the mode calculates the influence value of a single double-fed fan on the stability of the multi-machine power system; the analysis of the influence of the double-fed fan on the stability of the power system provided by the method and the system, and Compared with the traditional eigenvalue method, the physical meaning is clearer, and the action path of the electromechanical oscillation circuit can be displayed more clearly without depending on the example system. At the same time, the calculation pressure is greatly reduced, and it is convenient for engineering applications.

Description of drawings

A more complete understanding of the exemplary embodiments of the present invention can be had by referring to the following drawings:

Fig. 1 is a kind of flow chart of the grid stability control method based on the stability influence of double-fed wind turbine according to the specific embodiment of the present invention;

Fig. 2 is a structural diagram of a power grid stability control device based on the stability influence of a doubly-fed wind turbine according to a specific embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention will now be described with reference to the drawings; however, the present invention may be embodied in many different forms and are not limited to the embodiments described herein, which are provided for the purpose of exhaustively and completely disclosing the present invention. 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 do not limit the present invention. In the figures, the same units/elements are given the same reference numerals.

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

Fig. 1 is a flow chart of a power grid stability control method based on the stability influence of a doubly-fed wind turbine according to a specific embodiment of the present invention. As shown in Figure 1, the method includes:

Step 110, collect the operating parameters of the double-fed fan; the operating parameters include machine terminal voltage, output current, active power and reactive power;

In this embodiment, in order to provide a basis for the stability control of the power grid, the influence value of the doubly-fed fan on the stability of the power system is obtained by analyzing the operating parameters of the doubly-fed fan; further, the doubly-fed fan described in this embodiment It can be one or more. When considering multiple double-fed wind turbines, it is necessary to further consider the influence of the interaction between multiple double-fed wind turbines on the stability of the multi-machine power system.

Step 120, according to the operating parameters and the preset model, calculate and obtain the transfer function of the forward channel and the transfer function of the doubly-fed fan; the transfer function of the forward channel is the transfer function from the output power of the doubly-fed fan to the electromagnetic torque; The transfer function of the double-fed fan is the transfer function from the fan terminal voltage to the output power of the fan;

The formula for calculating the forward channel transfer function in the preset model is:

Among them, ΔT _e is the electromagnetic torque, ΔPQ ₁ is the output power of the fan,

The matrices A and B are obtained from the state space model of the multi-machine power system part. The state space model is calculated according to the operating parameters of the doubly-fed fan. The formula is:

P _w ＝V _sx I _wx +V _sy I _wy

Q _w ＝V _sy I _wx -V _sx I _wy

Among them, ΔV _s is the terminal voltage of the DFIG, ΔP _w and ΔQ _w are the output active and reactive power of the DFIG, respectively; I _w represents the output current of the DFIG, and the subscripts x and y represent the corresponding physical quantities in Components in the synchronous coordinate system; X _g is a column vector composed of all state variables in the multi-machine power system;

When a single double-fed fan is connected to a multi-machine power system, the state space model is expanded as,

Among them, δ represents the column vector composed of the power angles of all synchronous machines, ω represents the column vector composed of the angular velocities of all synchronous machines, z represents the column vector composed of all other state variables in the multi-machine power system, ΔPQ ₁ =[ΔP ₁ ΔQ ₁ ] ^T .

Step S20 is executed, the transfer function of the doubly-fed fan is calculated in the preset model; the transfer function of the doubly-fed fan is the transfer function from the fan terminal voltage to the output power of the fan; the formula for calculating the transfer function of the doubly-fed fan is,

Step 130, calculate the damping torque of the electromechanical oscillation circuit of the synchronous machine for a single double-fed fan connected to the multi-machine power system according to the forward channel transfer function, the double-fed fan transfer function and the synchronous machine angular velocity;

For the angular velocity of the synchronous machine, it is necessary to convert the input variable of the double-fed fan into the transfer function of the column vector of the angular velocity of the synchronous machine; The formula for the transfer function of the vector is,

Among them, Δω _k is the column vector composed of the angular velocity of the kth synchronous machine, λ _i is the ith eigenvalue of the open-loop A array in the expansion of the state space model, v _i is the right eigenvector corresponding to λ _i , v _ik is the value corresponding to Δω _k in v _i .

The formula for calculating the damping torque of a single doubly-fed fan connected to a multi-machine power system to the electromechanical oscillation circuit of a synchronous machine is:

ΔT _1Dk = D _1k Δω _k

Among them, D _1k ＝Re[F _k (λ _i )G _k (λ _i )γ _ik ], said D _1k ＝Re[F _k (λ _i )G _k (λ _i )γ _ik ] is paired by double-fed fan The electromagnetic torque of the electromechanical oscillating circuit of K synchronous machine is obtained, and the formula of described electromagnetic torque is,

Wherein, the K is a positive integer.

Step 140: Calculate the sensitivity to the damping coefficient of the synchronous machine in different oscillation modes according to the damping torque; calculate the formula for calculating the sensitivity to the damping coefficient of the synchronous machine in different oscillation modes according to the damping torque for:

Among them, S _ik is the sensitivity of the i-th oscillation mode to the damping coefficient of the k-th synchronous machine.

Step 150, according to the damping torque and the sensitivity of the damping coefficient, calculate the influence value of the single DFIG on the stability of the multi-machine power system; calculate the influence of the single DFIG on the multi-machine power system; The formula for the influence value of electromechanical system stability is:

Among them, _Δλi is the total influence value of the dynamic interaction between single wind turbine and multi-machine power system on the ith oscillation mode.

Step 160, perform pre-warning control on the power grid according to the influence value and a preset pre-warning threshold.

In this embodiment, there are many ways to carry out early warning control of the power grid through the calculated influence value, including real-time comparison between the preset influence value warning threshold and the influence value to perform early warning. The early warning threshold can be multi-level , forming a layered early warning.

Specifically, in this embodiment, a first warning threshold and a second warning threshold are set; the first warning threshold is smaller than the second warning threshold;

When the obtained impact value is below the first warning threshold, it is confirmed that the impact of the double-fed wind turbine on the stability of the power system is acceptable, and the double-fed wind turbine is kept connected to the power system;

When the obtained impact value is between the first early warning threshold and the second early warning threshold, the impact of the double-feed risk on the stability of the power system may be at risk, and the early warning is fed back to relevant staff for manual confirmation;

When the obtained influence value is above the second warning threshold, the impact of the doubly-fed wind turbine on the stability of the power system is relatively risky, and the connection of the doubly-fed wind turbine is disconnected, and an alarm is sent to relevant staff.

Further, in this embodiment, the dynamic interaction between multiple double-fed fans is also considered to affect the stability of the multi-machine power system;

When any two double-fed fans among the multiple double-fed fans are connected to the power system, the state space model of the multi-machine power system part is expanded as:

It can be obtained that the transfer function models of any two double-fed fans among the multiple double-fed fans are:

ΔPQ ₁ =G ₁ (s)ΔV ₁

ΔPQ ₂ =G ₂ (s)ΔV ₂

It can be concluded that

ΔV ₁ ＝C′ ₁ (s)ΔX _g +D′ ₁₂ (s)ΔPQ ₂

ΔV ₂ =C′ ₂ (s)ΔX _g +D′ ₂₁ (s)ΔPQ ₁

Among them, C' ₁ (s) = (ID ₁₁ G ₁ (s)) ^-1 [C ₁₁ C ₁₂ C ₁₃ ], D' ₁₂ (s) = (ID ₁₁ G ₁ (s)) ^-1 D ₁₂ , C' ₂ (s) = (ID ₂₂ G ₂ (s)) ^-1 [C ₂₁ C ₂₂ C ₂₃ ], D' ₂₁ (s) = (ID ₂₂ G ₂ (s)) ^-1 D ₂₁ ;

After the second double-fed fan is added, the influence on the electromechanical oscillation circuit of the power system can be divided into two parts, one part directly affects the circuit, and the other part interacts with the first double-fed fan, thereby Indirectly affect the electromechanical oscillation circuit; the interaction between the two doubly-fed fans is caused by the coupling between their input and output quantities ΔPQ and ΔV;

In the case where the two DFIGs are connected, if the above-mentioned damping torque analysis method is used, only the comprehensive influence of the two DFIGs can be obtained, but the impact of their previous dynamic interaction on each other cannot be obtained. The influence value of; Below by the method of decoupling, find the influence value to the damping characteristic of the first double-fed fan due to the addition of the second double-fed fan;

Before and after the dynamic addition of the second doubly-fed fan, the forward channel transfer function and the transfer function characteristics of the damping circuit of the first doubly-fed fan remain unchanged; It appears in the calculation part of the reconstruction of the input variable ΔV ₁ of the double-fed fan, which is also the part where the two fans are coupled; in the following, the dynamic interaction of the two double-fed fans is formally decoupled, and the calculation The influence value of the dynamic interaction between them on each other;

After calculation, we can get:

ΔPQ ₁ =G ₁ (s)C′ ₁ (s)ΔX _g +G ₁ (s)D′ ₁₂ (s)ΔPQ ₂

ΔPQ ₂ =G ₂ (s)C′ ₂ (s)ΔX _g +G ₂ (s)D′ ₂₁ (s)ΔPQ ₁

which is:

ΔPQ ₁ -G ₁ (s)D′ ₁₂ (s)ΔPQ ₂ =G ₁ (s)C′ ₁ (s)ΔX _g

-G ₂ (s)D′ ₂₁ (s)ΔPQ ₁ +ΔPQ ₂ ＝G ₂ (s)C′ ₂ (s)ΔX _g

In order to formally decouple the output variables ΔPQ ₁ and ΔPQ ₂ of the two double-fed fans, the above equation is eliminated, and the transfer function relationship between ΔPQ ₁ and ΔPQ ₂ and ΔX _g can be solved respectively as follows:

ΔPQ ₁ =[IG ₁ (s)D′ ₁₂ (s)G ₂ (s)D′ ₂₁ (s)] ^-1 G ₁ (s)[C′ ₁ (s)+D′ ₁₂ (s)G ₂ (s)C′ ₂ (s)]ΔX _g

ΔPQ ₂ =[IG ₂ (s)D′ ₂₁ (s)G ₁ (s)D′ ₁₂ (s)] ^-1 G ₂ (s)[C′ ₂ (s)+D′ ₂₁ (s)G ₁ (s)C′ ₁ (s)]ΔX _g

Then it can be obtained that after formal decoupling, the transfer function relationship between the input variables ΔV and ΔX _g of the two fans is:

ΔV ₁ =C″ ₁ (s)ΔX _g

ΔV ₂ =C″ ₂ (s)ΔX _g

in,

The coupling part of the two double-fed fans is implied in the transfer function expressions of C″ ₁ (s) and C″ ₂ (s), and the decoupling of the two double-fed fans is done formally;

For the first double-fed fan, only C′ ₁ (s) changed to C″ ₁ (s) in the damping circuit; in the above damping torque analysis process, only the input variable of the double-fed fan changed The refactoring process becomes:

According to the above damping torque analysis method, due to the dynamic interaction of the second DFIG, the amount of change in the damping torque of the first DFIG can be quantitatively described as:

The addition of the second double-fed fan affects the dynamic interaction of the first double-fed fan, and the resulting change in the electromechanical oscillation mode of the power system is:

Among them, _Δλi is the change in electromechanical oscillation mode of the power system caused by the addition of any second DFIG among the multiple DFIGs to the dynamic interaction of the first DFIG; ΔD _1k is the dynamic interaction of any second doubly-fed fan in the plurality of doubly-fed fans, resulting in the amount of change in the damping torque of the first doubly-fed fan.

In this calculation example, the two double-fed fans are marked as W ₁ and W ₂ respectively;

Table 1 is an influence value table of dynamic interaction between any two of multiple DFIGs in a power grid stability control method based on the stability influence of DFIGs according to a specific embodiment of the present invention. As shown in Table 1, the dynamic interaction has little effect on the two wind turbines.

Effect of Dynamic Interaction on W₁ Effect of Dynamic Interaction on W₂ Δλ₁ 0.0001+j0.0001 0.0004+j0.0001 Δλ₂ 0.0005+j0.0002 0 Δλ₃ 0-j0.0001 -0.0001+j0.0001

Table 1

Table 2 is a table of influence values on the three oscillation modes of the system when any two of multiple double-fed wind turbines are added separately in a power grid stability control method based on the stability influence of double-fed wind turbines according to a specific embodiment of the present invention; Table 3 It is a power grid stability control method based on the influence of the stability of DFIGs and a table of the influence values on the three oscillation modes of the system when any two of multiple DFIGs in the device are added at the same time in the specific embodiment of the present invention.

As shown in Tables 2 and 3, the effect of the dynamic interaction between the two fans on W ₁ will adversely affect the second oscillation mode; the effect of the dynamic interaction between the two fans on W ₁ will affect The first oscillation mode has an adverse effect; the other oscillations have little effect.

W₁ W₂ Δλ₁ 0.0009+j0.0003 0.0164-j0.0036 Δλ₂ 0.0018+j0.0061 -0.0009+j0.0006 Δλ₃ 0.0001-j0.0006 -0.0121-j0.0066

Table 2

W₁ W₂ total impact Δλ₁ 0.0010+j0.0004 0.0168-j0.0035 0.0178-j0.0031 Δλ₂ 0.0023+j0.0063 -0.0009+j0.0006 0.0014+j0.0069 Δλ₃ 0.0001-j0.0007 -0.0122-j0.0065 -0.0121-j0.0072

table 3

Fig. 2 is a structural diagram of a power grid stability control device based on the influence of the stability of a doubly-fed wind turbine according to a specific embodiment of the present invention. As shown in Figure 2, the device includes:

A collection unit 210, the collection unit 210 is used to collect the operating parameters of the doubly-fed fan; the operating parameters include machine terminal voltage, output current, active power and reactive power;

The transfer function calculation unit 220, the transfer function calculation unit 220 is used to calculate and obtain the transfer function of the forward channel and the transfer function of the double-fed fan according to the operating parameters and the preset model; the transfer function of the forward channel is the dual-fed fan. The transfer function from the output power of the fed fan to the electromagnetic torque; the transfer function of the double-fed fan is the transfer function from the fan terminal voltage to the output power of the fan;

A damping torque calculation unit 230, one end of the damping torque calculation unit 230 is connected to a damping coefficient sensitivity calculation unit 240, and the damping torque calculation unit 230 is used to And the angular velocity of the synchronous machine calculates the damping torque of the electromechanical oscillation circuit of the synchronous machine for a single double-fed fan connected to the multi-machine power system, and sends the damping torque result to the damping coefficient sensitivity calculation unit 240 and the single double-fed fan Fan feeder influence value calculation unit 250;

A damping coefficient sensitivity calculation unit 240, one end is connected with the damping torque calculation unit 230, and the other end is connected with a single double-fed fan influence value calculation unit 250; the damping coefficient sensitivity calculation unit 240 is used for Torque, calculating the sensitivity to the damping coefficient of the synchronous machine in different oscillation modes, and sending the sensitivity to the damping coefficient of the synchronous machine in the different oscillation modes to the influence value calculation unit 250 of a single double-fed fan;

The influence value calculation unit 250 of a single double-fed fan is connected to the damping torque calculation unit 230 and the damping coefficient sensitivity calculation unit 240 at one end, and is used to calculate the damping torque according to the sensitivity of the damping torque and the damping coefficient , calculating the influence value of the single double-fed fan on the stability of the multi-machine power system.

An early warning control unit 260, configured to perform early warning control on the power grid according to the influence value and a preset early warning threshold.

Further, the device also includes:

A plurality of double-fed fan influence value calculation units 270, one end of the plurality of double-fed fan influence value calculation units 270 is respectively connected to the damping torque calculation unit 230 and the damping coefficient sensitivity calculation unit 240, and the other end is connected to The influence value calculation unit 250 of the single double-fed wind turbine is connected to calculate the influence value of the dynamic interaction between multiple double-fed wind turbines on the stability of the multi-machine power system.

Further, it is characterized in that the device also includes:

Forward channel transfer function calculation unit 221, one end of the forward channel transfer function calculation unit 221 is connected to the damping torque calculation unit 230 for calculating the transmission of the single double-fed fan output power to the electromagnetic torque function result, and send the calculation result of the transfer function from the output power of the single double-fed fan to the electromagnetic torque to the damping torque calculation unit 230;

Double-fed fan transfer function calculation unit 222, one end of said double-fed fan transfer function calculation unit 222 is connected to said damping torque calculation unit 230; said double-fed fan transfer function calculation unit 222 is used to calculate said single double-fed fan The transfer function result of the terminal voltage of the single DFIG to the output power of the single DFIG, and the transfer function result of the terminal voltage of the single DFIG to the output power of the single DFIG is sent to the damping rotor Moment calculation unit 230;

Input variable reconstruction unit 223, one end of the input variable reconstruction unit 223 is connected to the damping torque calculation unit 230; the input variable reconstruction unit 223 is used to convert the input variable of the single double-fed fan Composing the transfer function of the column vector for the angular velocity of the synchronous machine, and converting the input variable of the single double-fed fan into the transfer function of the angular velocity of the synchronous machine and sending it to the damping torque calculation unit 230 .

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the present disclosure may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure the understanding of this description.

Those skilled in the art can understand that the modules in the device in the embodiment can be adaptively changed and arranged in one or more devices different from the embodiment. Modules or units or components in the embodiments may be combined into one module or unit or component, and furthermore may be divided into a plurality of sub-modules or sub-units or sub-assemblies. All features disclosed in this specification (including accompanying claims, abstract and drawings), as well as any method or method so disclosed, may be used in any combination, except that at least some of such features and/or processes or units are mutually exclusive. All processes or units of equipment are combined. Each feature disclosed in this specification (including accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. The step numbers involved in this specification are only used to distinguish each step, and are not used to limit the time or logical relationship between each step. Unless otherwise clearly defined in the text, the relationship between each step includes various possible Happening.

In addition, those skilled in the art will understand that although some embodiments described herein include some features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of the present disclosure. and form different embodiments. For example, any one of the embodiments claimed in the claims may be used in any combination.

The various component embodiments of the present disclosure may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. The present disclosure can also be implemented as an apparatus or system program (eg, computer program and computer program product) for performing a part or all of the methods described herein. Such a program realizing the present disclosure may be stored on a computer-readable medium, or may have the form of one or more signals. Such a signal may be downloaded from an Internet site, or provided on a carrier signal, or provided in any other form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the disclosure, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The disclosure can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a unit claim enumerating several systems, several of these systems can be embodied by one and the same item of hardware.

The above descriptions are only specific implementations of the present disclosure. It should be noted that those skilled in the art can make several improvements, modifications, and variations without departing from the spirit of the present disclosure. These improvements, Modifications and deformations should be considered as falling within the scope of protection of this application.

Claims (10)

1. a method for grid stability control based on the stability influence of double-fed wind turbine, it is characterized in that, described method comprises: Collecting the operating parameters of the doubly-fed fan; the operating parameters include machine terminal voltage, output current, active power and reactive power; According to the operating parameters and the preset model, calculate and obtain the transfer function of the forward channel and the transfer function of the double-fed fan; the transfer function of the forward channel is the transfer function from the output power of the double-fed fan to the electromagnetic torque; the double-fed fan The transfer function of the fan feeder is the transfer function from the fan terminal voltage to the output power of the fan; Based on the transfer function of the double-fed fan, determine the formula of the transfer function of the column vector composed of the angular velocity of the synchronous machine, and then calculate the transfer function of the column vector and the forward channel transfer function according to the electromagnetic torque formula to obtain the damping torque, and according to The damping torque is used to calculate the sensitivity to the damping coefficient of the synchronous machine in different oscillation modes; According to the damping torque and the sensitivity of the damping coefficient, calculate the influence value of a single double-fed fan on the stability of the multi-machine power system; Pre-warning control is performed on the power grid according to the influence value and a preset pre-warning threshold. 2. The method according to claim 1, characterized in that, before performing early warning control on the power grid according to the influence value and the preset early warning threshold, the method further comprises: according to the single double-fed fan For the influence value of the stability of the multi-machine power system, the dynamic interaction between multiple double-fed wind turbines is calculated to affect the stability of the multi-machine power system. 3. The method according to claim 2, wherein the formula for calculating the forward channel transfer function in the preset model is:

Among them, ΔT _e is the electromagnetic torque, ΔPQ ₁ is the output power of the fan, The matrices A and B are obtained from the state space model of the multi-machine power system part, and the state space model is:

Among them, ΔV _s is the terminal voltage of the DFIG, ΔP _w and ΔQ _w are the output active and reactive power of the DFIG, respectively; X _g is the column vector composed of all state variables in the multi-machine power system; When a single double-fed fan is connected to a multi-machine power system, the state space model is expanded as,

Among them, δ represents the column vector composed of the power angles of all synchronous machines, ω represents the column vector composed of the angular velocities of all synchronous machines, z represents the column vector composed of all other state variables in the multi-machine power system, ΔPQ ₁ =[ΔP ₁ ΔQ ₁ ] ^T ; The formula for calculating the transfer function of the doubly-fed fan in the preset model is,

The formula for converting the input variable of the double-fed fan into the transfer function of the angular velocity of the synchronous machine to form a column vector is,

Among them, Δω _k is the column vector composed of the angular velocity of the kth synchronous machine, λ _i is the ith eigenvalue of the open-loop A array in the expansion of the state space model, v _i is the right eigenvector corresponding to λ _i , v _ik is the value corresponding to Δω _k in v _i . 4. The method according to claim 3, characterized in that, the formula for calculating the damping torque of the electromechanical oscillation loop of the synchronous machine to the single double-fed fan connected to the multi-machine power system is: ΔT _1Dk = D _1k Δω _k Wherein, the D _1k =Re[F _k (λ _i )G _k (λ _i )γ _ik ], and the D _1k =Re[F _k (λ _i )G _k (λ _i )γ _ik ] is obtained by doubly fed The electromagnetic torque of the electromechanical oscillating circuit of the fan to the K station synchronization is obtained, and the formula of the electromagnetic torque is,

Wherein, the K is a positive integer. 5. method according to claim 4, is characterized in that, according to described damping torque, the formula of calculating the sensitivity to the damping coefficient of described synchronous machine under different oscillation modes is:

Among them, S _ik is the sensitivity of the i-th oscillation mode to the damping coefficient of the k-th synchronous machine. 6. The method according to claim 5, characterized in that, according to the sensitivity of the damping torque and the damping coefficient, calculating the influence value of the single double-fed fan on the stability of the multi-machine power system The formula is:

Among them, _Δλi is the total influence value of the dynamic interaction between single wind turbine and multi-machine power system on the ith oscillation mode. 7. The method according to claim 6, wherein, according to the influence value of the single double-fed fan on the stability of the multi-machine power system, the dynamics of any two of the multiple double-fed fans are calculated. The formula of interaction effect on power system stability is:

Among them, _Δλi is the change in electromechanical oscillation mode of the power system caused by the addition of any second DFIG among the multiple DFIGs to the dynamic interaction of the first DFIG; ΔD _1k is the Describe the dynamic interaction of any second DFIG among multiple DFIGs, resulting in the change in the damping torque of the first DFIG. 8. A power grid stability control device based on the stability influence of double-fed wind turbines, characterized in that the device comprises: A collection unit, the collection unit is used to collect the operating parameters of the doubly-fed fan; the operating parameters include machine terminal voltage, output current, active power and reactive power; A transfer function calculation unit, the transfer function calculation unit is used to calculate and obtain the transfer function of the forward channel and the transfer function of the double-fed fan according to the operating parameters and the preset model; the transfer function of the forward channel is the transfer function of the double-fed fan A transfer function from output power to electromagnetic torque; the transfer function of the double-fed fan is a transfer function from fan terminal voltage to fan output power; The damping torque calculation unit, based on the transfer function of the doubly-fed fan, determines the formula of the transfer function of the column vector composed of the angular velocity of the synchronous machine, and then calculates the transfer function of the column vector and the forward channel transfer function according to the electromagnetic torque formula Damping torque, and sending the damping torque result to the damping coefficient sensitivity calculation unit and the influence value calculation unit of a single double-fed fan; A damping coefficient sensitivity calculation unit, the damping coefficient sensitivity calculation unit is used to calculate the sensitivity to the damping coefficient of the synchronous machine in different oscillation modes according to the damping torque, and to calculate the sensitivity to the synchronous machine in the different oscillation modes The sensitivity of the damping coefficient of the machine is sent to the influence value calculation unit of a single double-fed fan; The influence value calculation unit of a single double-fed fan is connected to the damping torque calculation unit and the damping coefficient sensitivity calculation unit at one end, and is used to calculate the damping torque and the sensitivity of the damping coefficient according to the damping torque Describe the influence value of a single double-fed fan on the stability of multi-machine power system; An early warning control unit, configured to perform early warning control on the power grid according to the influence value and a preset early warning threshold. 9. The device according to claim 8, further comprising: A plurality of double-fed fan influence value calculation units, one end of the multiple double-fed fan influence value calculation unit is respectively connected to the damping torque calculation unit and the damping coefficient sensitivity calculation unit, and the other end is connected to the single The doubly-fed wind turbine influence value calculation unit is connected to calculate the influence value of the dynamic interaction between multiple doubly-fed wind turbines on the stability of the multi-machine power system. 10. The device according to claim 8, wherein the transfer function calculation unit comprises: a forward channel transfer function calculation unit, one end of the forward channel transfer function calculation unit is connected to the damping torque calculation unit connection, used to calculate the transfer function result from the output power of the single double-fed fan to the electromagnetic torque, and send the calculation result of the transfer function from the output power to the electromagnetic torque of the single double-fed fan to the damping torque computing unit; A doubly-fed fan transfer function calculation unit, one end of the doubly-fed fan transfer function calculation unit is connected to the damping torque calculation unit; the doubly-fed fan transfer function calculation unit is used to calculate the terminal voltage of the single doubly-fed fan to the transfer function result of the output power of the single doubly-fed fan, and send the transfer function result of the terminal voltage of the single doubly-fed fan to the output power of the single doubly-fed fan to the damping torque calculation unit; An input variable reconstruction unit, one end of the input variable reconstruction unit is connected to the damping torque calculation unit; the input variable reconstruction unit is used to convert the input variable of the single double-fed fan into the synchronous The angular velocity of the synchronous machine constitutes the transfer function of the column vector, and the input variable of the single double-fed fan is converted into the result of the transfer function of the angular velocity of the synchronous machine composed of the column vector and sent to the damping torque calculation unit.

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