Doubly-fed fan decoupling control method and device based on dynamic feed-forward compensation

Abstract

The invention discloses a double-fed fan decoupling control method and device based on dynamic feed-forward compensation, and belongs to the technical field of wind power generation. When the power grid frequency deviation in unit time and the power grid frequency change rate meet a first preset condition, starting an active compensation ring; and when the grid-connected point voltage deviation and the grid-connected point voltage change rate in unit time meet a second preset condition and the power grid frequency deviation and the power grid frequency change rate in unit time do not meet the first preset condition, starting a reactive compensation ring. According to the invention, adaptive control in consideration of the load sudden change degree and the system response capability is added, so that the power coupling rate can be greatly reduced, and adaptive frequency voltage decoupling support can be carried out on different load sudden change degrees; the problem of frequency and voltage stability caused by errors of the PLL under the condition that the doubly-fed fan is connected with a weak power grid is effectively relieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and more specifically, relates to a decoupling control method and device for a doubly-fed wind turbine based on dynamic feedforward compensation. Background Art

[0002] The current power system shows a trend of high proportion of new energy access, among which wind power generation systems dominated by double-fed wind turbines are developing rapidly. Existing onshore wind farms are mainly distributed in areas with abundant wind resources such as the three northern regions, and are often far away from load centers; at the same time, large-scale wind power is usually connected to the grid after boosting, resulting in a large impedance of wind power grid connection, and the AC system connected to it shows the characteristics of low short-circuit ratio. [3] , thus forming a scenario where wind power is connected to a weak grid, and the risk of instability in system frequency and voltage increases. Compared with the synchronization method of synchronous generators, the grid-following control of doubly fed wind turbines often obtains the amplitude, frequency and phase of the grid voltage through phase-locked loop feedback to achieve synchronization with the grid. At present, there are few studies on the power coupling characteristics and decoupling strategies caused by PLL of doubly fed wind turbines, and they mainly focus on exploring the impact of PLL on system stability.

[0003] However, under weak grid conditions, grid-following control has dynamic errors in voltage orientation, which eventually leads to mutual coupling of active power and reactive power, thereby affecting the dynamic performance of converter control and worsening the system's active and reactive power shortages. This further causes mutual influence between frequency regulation and voltage regulation. At the same time, in the case of sudden changes in system power flow, frequency and voltage fluctuations increase, increasing the risk of system collapse. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a decoupling control method and device for a doubly fed wind turbine based on dynamic feedforward compensation, the purpose of which is to solve the problem of insufficient power decoupling and subsequent frequency and voltage stability problems caused by inaccurate tracking of the voltage phase of the phase-locked loop at the grid connection point when the doubly fed wind turbine is connected to a weak power grid.

[0005] To achieve the above object, according to one aspect of the present invention, a decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation is provided, comprising:

[0006] In the scenario where the doubly-fed wind turbine is connected to a weak AC grid and adopts grid-following control, the grid frequency information and grid connection point voltage information are collected in real time; the grid frequency information includes: grid frequency deviation and grid frequency change rate per unit time; the grid connection point voltage information includes: grid connection point voltage deviation and grid connection point voltage change rate per unit time;

[0007] When the grid frequency deviation and the grid frequency change rate per unit time both exceed their respective corresponding first preset thresholds, the active compensation loop based on dynamic feedforward is started; when the grid connection point voltage deviation and the grid connection point voltage change rate per unit time both exceed their respective corresponding second preset thresholds and the grid frequency deviation and the grid frequency change rate per unit time do not exceed their respective corresponding first preset thresholds, the reactive compensation loop based on dynamic feedforward is started;

[0008] Wherein, the active compensation loop and the reactive compensation loop are both adaptively adjusted according to the severity of the power grid load accident;

[0009] When the grid frequency reaches the lowest point and the corresponding grid frequency change rate is equal to 0, all currently started compensation loops are closed.

[0010] In one embodiment, the active coupling value P in the active compensation loop based on dynamic feedforward is com It is expressed as: Among them, P s is the real-time changing active power, Q s is the reactive power that changes in real time, K Qδ is the coefficient of the relationship between reactive power and voltage phase angle, ΔQ is the reactive power output of the wind turbine, v0 is the initial voltage value, K QU is the relationship coefficient between reactive power and voltage amplitude.

[0011] In one embodiment, the active coupling value P in the active compensation loop based on dynamic feedforward is com It is expressed as: Among them, P s is the real-time changing active power, ΔQ is the reactive power output of the wind turbine, v0 is the initial voltage value, K QU is the relationship coefficient between reactive power and voltage amplitude.

[0012] In one embodiment, the reactive coupling value Q in the reactive compensation loop based on dynamic feedforward is com It is expressed as: Among them, P s is the real-time changing active power, Q s is the reactive power K that changes in real time Pδ is the relationship coefficient between active power and voltage phase angle, ΔP is the active power output of the fan, v0 is the initial voltage value, K PU is the relationship coefficient between reactive power and voltage amplitude.

[0013] In one embodiment, the reactive coupling value Q in the reactive compensation loop based on dynamic feedforward is com Expressed as: Q com =P s K PδΔP; where ΔP is the active power output of the fan, K Pδ is the relationship coefficient between active power and voltage phase angle.

[0014] In one embodiment, the parameters in the active power compensation loop of the dynamic feedforward are Among them, k P_QU is the P value of the active compensation loop PI controller, k P_QU,initial is the fault time k P_QU The initial value of k P_QU,initial =k p_fixed +k p，L0 ×(k P_QU,max -k p_fixed ), k P_QU,max is the maximum value after small signal stability analysis, k p_fixed is the fixed part of the adaptive active power accident variation coefficient, k p,L k is the active power accident severity measurement coefficient p，L =F p / F p-max , k p，L0 k p,L The initial value of F p It is used to measure the average frequency deviation within each Δt period, F p-max The maximum frequency deviation caused by the most severe load reactive change.

[0015] In one embodiment, the parameters in the reactive power compensation loop of the dynamic feedforward are Among them, k P_Pδ is the P value of the reactive power compensation loop PI controller, k P_Pδ,initial is the fault time k P_Pδ The initial value of k P_Pδ,max is the maximum value after small signal stability analysis, k P_Pδ,initial =k q_fixed +k q,L0 ×(k P_Pδ,max -k q_fixed ), k q_fixed is the fixed part of the adaptive reactive accident variation coefficient, k q,L k is the coefficient k for measuring the severity of reactive power accidents q,L =F q / F q,max , k q,L0 k q,L The initial value of F q It is used to measure the average voltage deviation within each Δt period, F q,max The maximum voltage deviation caused by the most severe load reactive change.

[0016] In one embodiment, the method further includes: after closing all currently activated compensation loops, using Evaluate the power decoupling effect after starting the compensation loop; PCD is the coupling degree, ΔX re f is the change in active / reactive reference value, and ΔY is the change in active / reactive power caused by the change in X.

[0017] According to another aspect of the present invention, a doubly-fed wind turbine decoupling control device based on dynamic feedforward compensation is provided, comprising:

[0018] An information acquisition module is used to collect grid frequency information and grid connection point voltage information in real time when the double-fed wind turbine is connected to a weak AC grid and adopts grid-following control; the grid frequency information includes: grid frequency deviation and grid frequency change rate per unit time; the grid connection point voltage information includes: grid connection point voltage deviation and grid connection point voltage change rate per unit time;

[0019] A compensation start-up module, used for starting an active compensation loop based on dynamic feedforward when the grid frequency deviation and the grid frequency change rate per unit time both exceed their respective corresponding first preset thresholds; starting a reactive compensation loop based on dynamic feedforward when the grid connection point voltage deviation and the grid connection point voltage change rate per unit time both exceed their respective corresponding second preset thresholds and the grid frequency deviation and the grid frequency change rate per unit time do not exceed their respective corresponding first preset thresholds;

[0020] Wherein, the active compensation loop and the reactive compensation loop are both adaptively adjusted according to the severity of the power grid load accident;

[0021] The compensation stop module is used to close all currently started compensation loops when the grid frequency reaches the lowest point and the corresponding grid frequency change rate is equal to 0.

[0022] According to another aspect of the present invention, a wind farm control system is provided, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0023] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0024] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0025] (1) The present invention provides a decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation. In a scenario where the doubly-fed wind turbine is connected to a weak AC power grid and adopts grid-following control, when the grid frequency deviation per unit time and the grid frequency change rate both exceed their respective corresponding first preset thresholds, the active compensation loop based on dynamic feedforward is started; when the grid connection point voltage deviation per unit time and the grid connection point voltage change rate both exceed their respective corresponding second preset thresholds and the grid frequency deviation per unit time and the grid frequency change rate do not exceed their respective corresponding first preset thresholds, the reactive compensation loop based on dynamic feedforward is started. The present invention adds adaptive control that considers the degree of load mutation and the system response capability, which can achieve a significant reduction in the power coupling rate and adaptive frequency-voltage decoupling support for different degrees of load mutation, effectively alleviating the problem of insufficient power decoupling caused by inaccurate tracking of the voltage phase of the phase-locked loop at the grid connection point when the doubly-fed wind turbine is connected to a weak power grid, thereby causing frequency and voltage stability problems. Furthermore, the ability of the doubly-fed wind turbine to suppress stator current overcurrent, voltage distortion and reduce system noise is improved, and the ability of the doubly-fed wind turbine in weak power grid conditions is improved.

[0026] (2) The active coupling value P in the active compensation loop based on dynamic feedforward described in this scheme com It is expressed as: Taking into account the active power coupling caused by reactive power changes, frequency and voltage decoupling support is achieved in the case of active power shortage.

[0027] (3) The active coupling value P in the active compensation loop based on dynamic feedforward described in this scheme com It is expressed as: Considering that doubly-fed wind turbines connected to weak power grids often transmit power through inductive transmission lines, reactive power mainly affects the voltage amplitude. The impact of reactive power on the voltage phase is ignored to achieve simplified analysis and control.

[0028] (4) The reactive coupling value Q in the reactive compensation loop based on dynamic feedforward described in this scheme com It is expressed as: Taking into account the reactive coupling caused by active power changes, frequency and voltage decoupling support is achieved in the case of reactive power shortage.

[0029] (5) The reactive coupling value Q in the reactive compensation loop based on dynamic feedforward described in this scheme com Expressed as: Q com =P s K Pδ ΔP; Considering that the active double-fed wind turbine connected to the weak power grid often transmits power through the inductive transmission line, the active power mainly affects the voltage phase. The influence of the active power on the voltage amplitude is ignored to achieve simplified analysis and control.

[0030] (6) In this scheme Further, The time when the decoupling loop is put into operation is recorded as T mal , the exit time is recorded as T rec In T mal At this moment, taking the active compensation loop parameters as an example, the parameters suddenly increase to k P-QU,initial Then the decoupling loop parameters are adjusted in real time according to the frequency situation monitored in real time, according to the slope decrease, and the system shortage changes until T rec At this moment, it is reduced to zero, which can realize the adaptive change of frequency information, voltage information and parameters of switching moment.

[0031] (7) This scheme measures the power coupling and effectiveness of the decoupling strategy under different short-circuit ratios and phase-locked loop bandwidths based on the formulas for the proposed coupling rate and decoupling rate. It is verified that the smaller the SCR of the grid system, the greater the wind turbine coupling rate, which means that the weaker the AC grid to which the doubly fed wind turbine is connected, the more serious the power coupling caused by the defects of the classic decoupling strategy. At the same time, reducing the bandwidth of the PLL will deepen the power coupling of the wind turbine, which may worsen the frequency and voltage support of the wind turbine. Furthermore, the SCR range applicable to the feedforward power decoupling loop is defined as: 1.5~3, which is suitable for weak grid systems with high penetration rates of new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart of a decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation provided in Example 1 of the present invention;

[0033] Figure 2 An overall control block diagram of a doubly-fed wind turbine decoupling control method based on dynamic feedforward compensation provided in Example 1 of the present invention;

[0034] Figure 3 A power coupling voltage-current vector relationship diagram of a double-fed wind turbine grid-side converter under a weak power grid provided in Example 1 of the present invention;

[0035] Figure 4 A diagram showing power coupling and decoupling before and after compensation in different SCR systems provided in Example 1 of the present invention;

[0036] Figure 5 A schematic diagram of changes in wind turbine active power, reactive power, frequency, and grid connection point voltage before and after decoupling provided by Embodiment 1 of the present invention under changes in active / reactive reference values;

[0037] Figure 6 A schematic diagram of the changes in wind turbine active power, reactive power, frequency, and grid connection point voltage before and after decoupling provided in Example 1 of the present invention under different degrees of active / reactive load changes in the system. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] Example 1

[0040] like Figure 1 and Figure 2 As shown, the present invention provides a decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation, comprising the following steps.

[0041] S1: In the scenario where the doubly-fed wind turbine is connected to a weak AC grid and adopts grid-following control, the grid frequency information and grid connection point voltage information are collected in real time; the grid frequency information includes: grid frequency deviation and grid frequency change rate per unit time; the grid connection point voltage information includes: grid connection point voltage deviation and grid connection point voltage change rate per unit time.

[0042] S2: When the grid frequency deviation and the grid frequency change rate per unit time both exceed their respective first preset thresholds, the active compensation loop based on dynamic feedforward is started; when the grid connection point voltage deviation and the grid connection point voltage change rate per unit time both exceed their respective second preset thresholds and the grid frequency deviation and the grid frequency change rate per unit time do not exceed their respective first preset thresholds, the reactive compensation loop based on dynamic feedforward is started; wherein both the active compensation loop and the reactive compensation loop are adaptively adjusted according to the severity of the grid load accident.

[0043] S3: When the grid frequency reaches the lowest point and the corresponding grid frequency change rate is equal to 0, all currently started compensation loops are closed.

[0044] Figure 3 The power coupling voltage and current vector relationship diagram of the grid-side converter of the double-fed wind turbine under weak power grid is shown in Figure 2. Figure 3 The power coupling voltage and current vector relationship of the double-fed wind turbine grid-side converter under the weak power grid is analyzed. Under the condition of weak power grid, the active and reactive power decoupling is not complete, and the active and reactive power coupling is quantified:

[0045] P s =|v pcc |·[|i q0 +Δi qQ |sinΔδ Q +|i d0 |cosΔδ Q ];

[0046] Q s =|v pcc|·[|i d0 +Δi dP |sinΔδ P +|i q0 |cosΔδ P ];

[0047]

[0048] Where P s is the real-time changing active power, Q s Real-time changing reactive power, v pcc is the voltage amplitude of the PCC point after the active or reactive power changes, i.e., the dq current changes, Δδ P , Δδ Q As P ref , Q ref The voltage phase angle difference changes accordingly. Δv P , Δv Q As P ref , Q ref The voltage amplitude difference changes.

[0049]

[0050] Use F p To measure the frequency deviation per Δt, the value when the frequency just exceeds the normal range is the preset threshold RoCoF th With F pth Similar to frequency, the voltage change rate and F are defined q To measure the voltage deviation every Δt seconds, the value when the frequency range exceeds the normal range is the preset threshold RoCoU th With F qth When the frequency parameter is greater than the preset threshold, the active compensation loop starts. When the voltage parameter is greater than the preset threshold, the reactive compensation loop starts.

[0051] Due to the support of the fan on the frequency and voltage, there is a transient process, and the frequency will recover from the lowest point to the steady state. During this process, the fan is in the process of increasing active power, and the dynamic error brought by the phase-locked loop is relatively reduced. If the control is still continued, the complex feedforward process will reduce the response speed of the fan to the reference value, and the benefit brought by the decoupling loop will be reduced, so the decoupling loop exits the control.

[0052] Figure 4 The power coupling and decoupling diagrams before and after compensation under different SCR systems provided by the embodiment of the present invention change the short-circuit ratio of the power system, test the power coupling of systems with different strengths and the decoupling rate before and after decoupling. It can be seen that the short-circuit ratio SCR range applicable to the feedforward power decoupling loop is: 1.5~3, which is suitable for weak power grid systems with high penetration of new energy.

[0053] In one embodiment, the active coupling value P in the active compensation loop based on dynamic feedforward com It is expressed as: Among them, P s is the real-time changing active power. In one embodiment, the active coupling value P in the active power compensation loop based on dynamic feedforward is com It is expressed as: Among them, P s is the real-time changing active power, K Qδ is the coefficient of the relationship between reactive power and voltage phase angle, ΔQ is the reactive power output of the wind turbine, v0 is the initial voltage value, K QU is the relationship coefficient between reactive power and voltage amplitude.

[0054] Specifically, the active coupling value P in the active compensation loop based on dynamic feedforward is com The expression is:

[0055]

[0056] In one embodiment, the reactive coupling value Q in the reactive compensation loop based on dynamic feedforward com It is expressed as: In one embodiment, the reactive coupling value Q in the reactive compensation loop based on dynamic feedforward com Expressed as: Q com =P s K Pδ ΔP; where P s is the real-time changing active power, Q s is the reactive power K that changes in real time Pδ is the relationship coefficient between active power and voltage phase angle, ΔP is the active power output of the fan, v0 is the initial voltage value, K PU is the relationship coefficient between reactive power and voltage amplitude.

[0057] Specifically, the reactive coupling value Q in the active compensation loop based on dynamic feedforward is com The expression is:

[0058] Therefore, by dynamically quantifying the active coupling value P when the reactive reference value changes com Reactive coupling value Q when the active reference value changes com And by compensating it to the power outer loop reference value on the RSC side through feedforward compensation, the power coupling phenomenon caused by the time-varying error of the PLL tracking voltage phase angle can be decoupled.

[0059] When the frequency or voltage drops or rises significantly, the absolute value of its rate of change will increase dramatically. At this time, the decoupling loop is started to quickly decouple the frequency / voltage and reduce the risk of system instability caused by power coupling.

[0060] Active coupling value P when the state-quantized reactive reference value changes com Reactive coupling value Q when the active reference value changes com , and compensate it to the power outer loop reference value on the RSC side through feedforward compensation. When the doubly fed wind turbine is connected to a weak power grid, in order to reduce the voltage drop during long-distance transmission and improve the line transmission efficiency, the X / R of the transmission line is often large. Power is transmitted through inductive transmission lines. Active power mainly affects the voltage phase, and reactive power mainly affects the voltage amplitude. In the process of quantifying the coupled power, we only consider the two branches of the change in voltage amplitude caused by reactive power changes and the change in voltage phase caused by active power changes.

[0061] At the same time, in order to further optimize the strategy, the parameter K Pδ , K QU The PI controller is directly used to improve the applicability and robustness of the decoupling strategy. Finally, the active and reactive coupling quantities quantified in the GSC are compensated to the reference value of the power outer loop of the RSC to obtain the overall dynamic compensation control.

[0062] In one embodiment, the parameters in the active power compensation loop of the dynamic feedforward are:

[0063]

[0064] Among them, k P_QU is the P value of the active compensation loop PI controller, k P_QU,initial is the fault time k P_QU The initial value of k P_QU,max is the maximum value after small signal stability analysis, k p_fixed is the fixed part of the adaptive active power accident variation coefficient, k p,L k is the active power accident severity measurement coefficient p，L =F p / F p-max , F p It is used to measure the average frequency deviation within each Δt period, F p-max The maximum frequency deviation caused by the most severe load reactive change.

[0065] In one embodiment, the parameters in the reactive power compensation loop of the dynamic feedforward are:

[0066]

[0067]

[0068] Among them, k P_Pδ is the P value of the reactive power compensation loop PI controller, k P_Pδ,initial is the fault time k P_Pδ The initial value of k P_Pδ,max is the maximum value after small signal stability analysis, k q_fixed is the fixed part of the adaptive reactive accident variation coefficient, k q,L k is the coefficient k for measuring the severity of reactive power accidents q,L =F q / F q,max , F q It is used to measure the average voltage deviation within each Δt period, F q,max The maximum voltage deviation caused by the most severe load reactive change.

[0069] When the active power of the system suddenly changes, it is mainly the active coupling compensation loop that plays a role. At this time, the frequency of the system fluctuates more than the voltage, and the active power shortage is proportional to the frequency change rate. Similarly, when the reactive power suddenly changes, it is mainly the reactive coupling compensation loop that plays a role. The voltage oscillation rate is higher than the frequency change rate, and the reactive power shortage is proportional to the voltage change rate.

[0070] Among them, F p0 is the frequency deviation within Δt after the accident, F p,max is the maximum frequency deviation caused by the preset most serious load active power mutation; similarly, F q0 are the voltage deviation within Δt after the accident, F q,max The maximum voltage deviation caused by the preset most serious load reactive power mutation. fixed is the fixed part of the adaptive accident variation coefficient, including k p_fixed With k q_fixed , usually corresponding to k p,max value to ensure that k P,initial In a suitable range of values ​​[k fixed ,k p,max ].

[0071] The time when the decoupling loop is put into operation is recorded as T mal , the exit time is recorded as T rec In T mal At this moment, taking the active compensation loop parameters as an example, the parameters suddenly increase to k P-QU,initial Then the decoupling loop parameters are adjusted in real time according to the frequency situation monitored in real time, according to the slope decrease, and the system shortage changes until T rec moment, reduced to zero.

[0072] In one embodiment, the method further includes: after closing all currently activated compensation loops, using Evaluate the power decoupling effect after starting the compensation loop; PCD is the coupling degree,

[0073] At the same time, the peak value of the first oscillation cycle after the accident is defined as the coupling amount, and the reactive / active relative coupling amount caused by the change of the active / reactive reference value is defined as the coupling degree. The higher the coupling degree, the more serious the power coupling of the internal control of the wind turbine.

[0074] The decoupling rate is defined to measure the decoupling ability of the dynamic feedforward compensation loop, that is, the ratio of the coupling degree difference before and after decoupling to the coupling degree before decoupling. The higher the decoupling rate, the better the decoupling effect of the feedforward power decoupling loop. Where PCD is the coupling degree, ΔX ref is the change of active / reactive reference value, ΔY is the change of active / reactive power caused by the change of X, and DPD is the decoupling rate.

[0075] in, Figure 5 A schematic diagram of changes in wind turbine active power, reactive power, frequency, and grid connection point voltage before and after decoupling provided in this embodiment under changes in active / reactive reference values; Figure 6 The present embodiment provides a schematic diagram of the changes in active power, reactive power, frequency, and grid-connected point voltage of the wind turbine before and after decoupling under different degrees of active / reactive load changes in the system. The present invention uses feedforward compensation to compensate the quantized power coupling component to the power outer loop reference value controlled by the rotor-side converter, and finally realizes the frequency and voltage decoupling support control of the doubly-fed wind turbine, solving the problem of insufficient power decoupling of the doubly-fed wind turbine under weak grid conditions due to inaccurate tracking of the voltage phase of the phase-locked loop at the grid-connected point, which in turn causes the stability problem of frequency and voltage.

[0076] Example 2

[0077] An embodiment of the present invention provides a doubly-fed wind turbine decoupling control device based on dynamic feedforward compensation, comprising: an information acquisition module, a compensation start module and a compensation stop module.

[0078] The information acquisition module is used to collect grid frequency information and grid connection point voltage information in real time when the doubly-fed wind turbine is connected to a weak AC grid and adopts grid-following control; the grid frequency information includes: grid frequency deviation and grid frequency change rate per unit time; the grid connection point voltage information includes: grid connection point voltage deviation and grid connection point voltage change rate per unit time.

[0079] The compensation start-up module is used to start the active compensation loop based on dynamic feedforward when the grid frequency deviation and the grid frequency change rate per unit time both exceed their respective corresponding first preset thresholds; and to start the reactive compensation loop based on dynamic feedforward when the grid connection point voltage deviation and the grid connection point voltage change rate per unit time both exceed their respective corresponding second preset thresholds and the grid frequency deviation and the grid frequency change rate per unit time do not exceed their respective corresponding first preset thresholds; wherein both the active compensation loop and the reactive compensation loop are adaptively adjusted according to the severity of the grid load accident.

[0080] The compensation stop module is used to close all currently started compensation loops when the grid frequency reaches the lowest point and the corresponding grid frequency change rate is equal to 0.

[0081] Example 3

[0082] An embodiment of the present invention provides a wind farm control system, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0083] Example 4

[0084] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method are implemented.

[0085] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation, characterized in that: include: When the doubly-fed wind turbine is connected to a weak AC grid and adopts grid-following control, the grid frequency information and grid connection point voltage information are collected in real time; The grid frequency information includes: the grid frequency deviation and the grid frequency change rate per unit time; the grid connection point voltage information includes: the grid connection point voltage deviation and the grid connection point voltage change rate per unit time; When the grid frequency deviation and the grid frequency change rate per unit time both exceed their respective corresponding first preset thresholds, the active compensation loop based on dynamic feedforward is started; when the grid connection point voltage deviation and the grid connection point voltage change rate per unit time both exceed their respective corresponding second preset thresholds and the grid frequency deviation and the grid frequency change rate per unit time do not exceed their respective corresponding first preset thresholds, the reactive compensation loop based on dynamic feedforward is started; Wherein, the active compensation loop and the reactive compensation loop are both adaptively adjusted according to the severity of the power grid load accident; When the grid frequency reaches the lowest point and the corresponding grid frequency change rate is equal to 0, all currently started compensation loops are closed.

2. The decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation according to claim 1, characterized in that: The active coupling value P in the active compensation loop based on dynamic feedforward is com It is expressed as: Among them, P s is the real-time changing active power, Q s is the reactive power that changes in real time, K Qδ is the coefficient of the relationship between reactive power and voltage phase angle, ΔQ is the reactive power output of the wind turbine, v0 is the initial voltage value, K QU is the relationship coefficient between reactive power and voltage amplitude.

3. The decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation according to claim 1, characterized in that: The active coupling value P in the active compensation loop based on dynamic feedforward is com It is expressed as: Among them, P s is the real-time changing active power, ΔQ is the reactive power output of the wind turbine, v0 is the initial voltage value, K QU is the relationship coefficient between reactive power and voltage amplitude.

4. The decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation according to claim 1, characterized in that: The reactive coupling value Q in the reactive compensation loop based on dynamic feedforward com It is expressed as: Among them, P s is the real-time changing active power, Q s is the reactive power K that changes in real time Pδ is the relationship coefficient between active power and voltage phase angle, ΔP is the active power output of the fan, v0 is the initial voltage value, K PU is the relationship coefficient between reactive power and voltage amplitude.

5. The decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation according to claim 1, characterized in that: The reactive coupling value Q in the reactive compensation loop based on dynamic feedforward com Expressed as: Q com =P s K Pδ ΔP; where ΔP is the active power output of the fan, K Pδ is the relationship coefficient between active power and voltage phase angle.

6. The decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation according to claim 1, characterized in that: The parameters in the active power compensation loop of the dynamic feedforward are Among them, k P_QU is the P value of the active compensation loop PI controller, k P_QU,initial is the fault time k P_QU The initial value of k P_QU,initial =k p_fixed +k p，L0 ×(k P_QU,max -k p_fixed ), k P_QU,max is the maximum value after small signal stability analysis, k p_fixed is the fixed part of the adaptive active power accident variation coefficient, k p,L k is the active power accident severity measurement coefficient p，L =F p / F p-max , k p，L0 k p,L The initial value of F p It is used to measure the average frequency deviation within each Δt period, F p-max The maximum frequency deviation caused by the most severe load reactive change.

7. The decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation according to claim 1, characterized in that: The parameters in the dynamic feedforward reactive power compensation loop are Among them, k P_Pδ is the P value of the reactive power compensation loop PI controller, k P_Pδ,initial is the fault time k P_Pδ The initial value of k P_Pδ,max is the maximum value after small signal stability analysis, k P_Pδ,initial =k q_fixed +k q,L0 ×(k P_Pδ,max -k q_fixed ), k q_fixed is the fixed part of the adaptive reactive accident variation coefficient, k q,L k is the coefficient k for measuring the severity of reactive power accidents q,L =F q / F q,max , k q,L0 k q,L The initial value of F q It is used to measure the average voltage deviation within each Δt period, F q,max The maximum voltage deviation caused by the most severe load reactive change.

8. The decoupling control method for a doubly-fed wind turbine based on dynamic feedforward compensation according to any one of claims 1 to 7, characterized in that: Also includes: After closing all currently enabled compensation loops, use Evaluate the power decoupling effect after starting the compensation loop; Among them, PCD is the coupling degree, ΔX ref is the change in active / reactive reference value, and ΔY is the change in active / reactive power caused by the change in X.

9. A doubly-fed wind turbine decoupling control device based on dynamic feedforward compensation, characterized in that: include: The information collection module is used to collect grid frequency information and grid connection point voltage information in real time when the doubly-fed wind turbine is connected to a weak AC grid and adopts grid-following control; The grid frequency information includes: the grid frequency deviation and the grid frequency change rate per unit time; the grid connection point voltage information includes: the grid connection point voltage deviation and the grid connection point voltage change rate per unit time; A compensation start-up module, used for starting an active compensation loop based on dynamic feedforward when the grid frequency deviation and the grid frequency change rate per unit time both exceed their respective corresponding first preset thresholds; starting a reactive compensation loop based on dynamic feedforward when the grid connection point voltage deviation and the grid connection point voltage change rate per unit time both exceed their respective corresponding second preset thresholds and the grid frequency deviation and the grid frequency change rate per unit time do not exceed their respective corresponding first preset thresholds; Wherein, the active compensation loop and the reactive compensation loop are both adaptively adjusted according to the severity of the power grid load accident; The compensation stop module is used to close all currently started compensation loops when the grid frequency reaches the lowest point and the corresponding grid frequency change rate is equal to 0.

10. A wind farm control system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

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