Method and device for suppressing transient voltage fluctuation of double-high power system

Abstract

The invention relates to the technical field of electric power systems, in particular to a transient voltage fluctuation suppression method and device for a double-high electric power system, and the method comprises the steps: activating a transient voltage fluctuation suppression strategy of the electric power system when the voltage of a grid-connected point under the rated output of a wind turbine generator in the electric power system is detected to be smaller than or equal to a preset voltage, then calculating the maximum active power and the minimum reactive power output by the wind turbine generator set meeting the voltage fluctuation suppression condition, further determining a pitch angle adjustment value of the wind turbine generator set and a generator speed reference value, adjusting the pitch angle of the wind turbine generator set by using the pitch angle adjustment value, and calculating the pitch angle of the wind turbine generator set based on the generator speed reference value. And switching a grid-side converter of the wind turbine generator set from a constant power control mode to a direct-current voltage control mode so as to suppress transient voltage fluctuation of a power system. Therefore, the problems that in the prior art, voltage fluctuation caused by repeated low-voltage penetration cannot be restrained, the risk of off-network is caused, and the safety and stability of a power system are harmed are solved.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular to a method and device for suppressing transient voltage fluctuations in a dual-high power system. Background Art

[0002] Under weak grid conditions, when wind turbines face the LVRT (Low Voltage Ride-Through) recovery process, if their power control switching and recovery strategies are not properly designed, it is very easy to induce violent fluctuations in the grid connection point voltage. This unstable voltage fluctuation will not only cause wind turbines to frequently experience low voltage ride-through states, but may also pose a threat to the stability of the entire power system, increase the risk of wind turbines being disconnected from the grid and even causing power outages. Therefore, in order to effectively solve this problem and ensure that wind turbines can smoothly transition and quickly recover during the grid voltage drop and subsequent recovery process, and avoid falling into the low voltage ride-through state again, it is urgent to propose an effective method for suppressing transient voltage fluctuations. In the related art, the methods for suppressing transient voltage fluctuations mainly include reducing the low voltage ride-through reactive current coefficient and changing the active control strategy of the unit during the ride-through period.

[0003] However, the method of reducing the reactive current coefficient during low voltage ride-through in related technologies can only reduce the amplitude of voltage fluctuations, while the method of increasing the active current as much as possible to maintain the active power before the fault will cause the wind turbine to be in a low voltage ride-through state all the time. The unloading circuit continues to operate and may exceed its thermal stability limit, causing the risk of disconnection from the grid and endangering the safety and stability of the power system, which needs to be solved urgently. Summary of the invention

[0004] The present application provides a method and device for suppressing transient voltage fluctuations in a dual-high power system, so as to solve the problem in the related technology that reducing the reactive current coefficient can only reduce the voltage fluctuation amplitude, while increasing the active current to maintain the pre-fault power will cause the wind turbine to be in a low voltage ride-through state for a long time, which has the risk of causing disconnection from the grid and endangering the safety and stability of the power system.

[0005] The first aspect of the present application provides a method for suppressing transient voltage fluctuations in a dual-high power system, comprising the following steps: obtaining the grid-connected point voltage at the rated output of a wind turbine in the power system, and detecting whether the grid-connected point voltage is less than or equal to a preset voltage; when it is detected that the grid-connected point voltage is less than or equal to the preset voltage, activating the transient voltage fluctuation suppression strategy of the power system to calculate the maximum active power and minimum reactive power output by the wind turbine to meet the preset voltage fluctuation suppression conditions; based on the maximum active power and the minimum reactive power, determining the pitch angle adjustment value and the generator speed reference value of the wind turbine, so as to adjust the pitch angle of the wind turbine using the pitch angle adjustment value, and based on the generator speed reference value, switching the grid-side converter of the wind turbine from a constant power control mode to a DC voltage control mode to suppress transient voltage fluctuations in the power system.

[0006] Optionally, in one embodiment of the present application, obtaining the grid-connected point voltage at the rated output of the wind turbine in the power system includes: collecting the rated active power and the rated reactive power during the operation of the wind turbine; and determining the grid-connected point voltage at the rated output of the wind turbine in the power system using the rated active power, the rated reactive power and the equivalent impedance of the target external power grid.

[0007] Optionally, in one embodiment of the present application, based on the generator speed reference value, switching the grid-side converter of the wind turbine set from the constant power control mode to the DC voltage control mode includes: collecting the actual speed of the generator in the wind turbine set; detecting whether the difference between the actual speed of the generator and the generator speed reference value is less than a preset speed value; when detecting that the difference between the actual speed of the generator and the generator speed reference value is less than the preset speed value, switching the grid-side converter of the wind turbine set from the constant power control mode to the DC voltage control mode.

[0008] Optionally, in one embodiment of the present application, the calculation formula of the grid connection point voltage is:

[0009]

[0010] Among them, U is the voltage at the grid connection point of the wind turbine; P is the rated active power generated by the wind turbine; Q is the rated reactive power generated by the wind turbine; E is the equivalent potential of the grid; R is the equivalent resistance of the grid; and X is the equivalent reactance of the grid.

[0011] Optionally, in one embodiment of the present application, the formula for switching DC voltage control is:

[0012] I dref =k p (U dcref-U dc )+k i ∫(U dcref -U dc )dt |ω-ω op |<ω lim

[0013] Among them, ω op is the generator speed reference value corresponding to the maximum output power of the wind turbine; ω is the actual generator speed; ω lim is the threshold of the difference between the actual speed of the generator and the reference speed; I dref is the active reference value of the grid-side converter; k p , k i are the proportional and integral coefficients of constant DC voltage control respectively; U dcref is the DC voltage reference value; U dc is the actual value of DC voltage.

[0014] The second aspect of the present application provides a device for suppressing transient voltage fluctuations in a dual-high power system, including: an acquisition module, used to obtain the grid-connected point voltage under the rated output of the wind turbine in the power system, and detect whether the grid-connected point voltage is less than or equal to a preset voltage; a processing module, used to activate the transient voltage fluctuation suppression strategy of the power system when it is detected that the grid-connected point voltage is less than or equal to the preset voltage, so as to calculate the maximum active power and minimum reactive power output by the wind turbine to meet the preset voltage fluctuation suppression conditions; a control module, used to determine the pitch angle adjustment value and the generator speed reference value of the wind turbine based on the maximum active power and the minimum reactive power, so as to adjust the pitch angle of the wind turbine using the pitch angle adjustment value, and switch the grid-side converter of the wind turbine from the constant power control mode to the DC voltage control mode based on the generator speed reference value, so as to suppress transient voltage fluctuations in the power system.

[0015] Optionally, in one embodiment of the present application, the acquisition module includes: a first acquisition unit, used to collect the rated active power and rated reactive power during the operation of the wind turbine; a determination unit, used to determine the grid connection point voltage at the rated output of the wind turbine in the power system using the rated active power, the rated reactive power and the equivalent impedance of the target external power grid.

[0016] Optionally, in one embodiment of the present application, the control module includes: a second acquisition unit, used to collect the actual speed of the generator in the wind turbine group; a detection unit, used to detect whether the difference between the actual speed of the generator and the generator speed reference value is less than a preset speed value; and a processing unit, used to switch the grid-side converter of the wind turbine group from the constant power control mode to the DC voltage control mode when it is detected that the difference between the actual speed of the generator and the generator speed reference value is less than the preset speed value.

[0017] Optionally, in one embodiment of the present application, the calculation formula of the grid connection point voltage is:

[0018]

[0019] Among them, U is the voltage at the grid connection point of the wind turbine; P is the rated active power generated by the wind turbine; Q is the rated reactive power generated by the wind turbine; E is the equivalent potential of the grid; R is the equivalent resistance of the grid; and X is the equivalent reactance of the grid.

[0020] Optionally, in one embodiment of the present application, the formula for switching DC voltage control is:

[0021] I dref =k p (U dcref -U dc )+k i ∫(U dcref -U dc )dt |ω-ω op |<ω lim

[0022] Among them, ω op is the generator speed reference value corresponding to the maximum output power of the wind turbine; ω is the actual generator speed; ω lim is the threshold of the difference between the actual speed of the generator and the reference speed; I dref is the active reference value of the grid-side converter; k p , k i are the proportional and integral coefficients of constant DC voltage control respectively; U dcref is the DC voltage reference value; U dc is the actual value of DC voltage.

[0023] The third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for suppressing transient voltage fluctuations in a dual-high power system as described in the above embodiment.

[0024] A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, which, when executed by a processor, implements the above method for suppressing transient voltage fluctuations in a dual-high power system.

[0025] A fifth aspect of the present application provides a computer program product, including a computer program, which, when executed, is used to implement the above method for suppressing transient voltage fluctuations in a dual-high power system.

[0026] The embodiment of the present application can activate the transient voltage fluctuation suppression strategy of the power system when it is detected that the grid connection point voltage under the rated output of the wind turbine in the power system is less than or equal to a certain voltage threshold, so as to calculate the maximum active power and minimum reactive power output by the wind turbine to meet the voltage fluctuation suppression conditions, and then determine the pitch angle adjustment value and the generator speed reference value of the wind turbine, so as to adjust the pitch angle of the wind turbine using the pitch angle adjustment value, and switch the grid-side converter of the wind turbine from the constant power control mode to the DC voltage control mode based on the generator speed reference value, so as to suppress the transient voltage fluctuation of the power system, effectively prevent the wind turbine from disconnecting from the grid, and improve the safety and stability of the power system. Thus, the problems that the voltage fluctuation caused by repeated low penetration cannot be suppressed in the related technology, which has the risk of causing disconnection from the grid and endangers the safety and stability of the power system are solved.

[0027] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0029] Figure 1 It is a flow chart of a method for suppressing transient voltage fluctuations in a dual-high power system provided according to an embodiment of the present application;

[0030] Figure 2 This is a flow chart of a method for suppressing transient voltage fluctuations in a dual-high power system according to a specific embodiment of the present application;

[0031] Figure 3 A schematic diagram of a specific embodiment of the present application for suppressing transient voltage fluctuations after a high-proportion renewable energy transmission line is disconnected from one circuit due to a fault;

[0032] Figure 4 It is a structural schematic diagram of a device for suppressing transient voltage fluctuations in a dual-high power system provided according to an embodiment of the present application;

[0033] Figure 5It is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0034] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0035] The following describes the method and device for suppressing transient voltage fluctuations in a dual-high power system of the embodiment of the present application with reference to the accompanying drawings. In view of the fact that reducing the reactive current coefficient in the related technology mentioned in the background technology center can only reduce the voltage fluctuation amplitude, while increasing the active current to maintain the pre-fault power will cause the wind turbine to be in a low voltage ride-through state for a long time, which has the risk of causing disconnection from the grid and endangering the safety and stability of the power system, the present application provides a method for suppressing transient voltage fluctuations in a dual-high power system, in which when it is detected that the grid connection point voltage under the rated output of the wind turbine in the power system is less than or equal to a certain voltage threshold, the transient voltage fluctuation suppression strategy of the power system can be activated to calculate the maximum active power and minimum reactive power output by the wind turbine to meet the voltage fluctuation suppression conditions, and then determine the pitch angle adjustment value and the generator speed reference value of the wind turbine, so as to adjust the pitch angle of the wind turbine using the pitch angle adjustment value, and switch the grid-side converter of the wind turbine from the fixed power control mode to the DC voltage control mode based on the generator speed reference value, so as to suppress transient voltage fluctuations in the power system, effectively prevent wind turbine disconnection events, and improve the safety and stability of the power system. This solves the problem that the related technology cannot suppress voltage fluctuations caused by repeated low voltage breakthroughs, which poses a risk of causing grid disconnection and endangers the safety and stability of the power system.

[0036] Specifically, Figure 1 A flow chart of a method for suppressing transient voltage fluctuations in a dual-high power system provided in an embodiment of the present application.

[0037] like Figure 1 As shown, the method for suppressing transient voltage fluctuations in the dual-high power system includes the following steps:

[0038] In step S101, the grid connection point voltage at the rated output of the wind turbine in the power system is obtained, and it is detected whether the grid connection point voltage is less than or equal to a preset voltage.

[0039] In the embodiment of the present application, the preset voltage is a voltage threshold at which the wind turbine generator system enters a low-voltage breakdown state.

[0040] It can be understood that the embodiment of the present application can obtain the grid connection point voltage under the rated output of the wind turbine in the power system. For example, the grid connection point voltage under the normal operation state (i.e., rated output) of the wind turbine can be calculated according to the equivalent impedance of the external power grid and the collected power value, and it can be detected whether the grid connection point voltage is less than or equal to the voltage threshold U of the wind turbine entering the low-breakthrough state. lim , so as to determine whether it is necessary to activate the transient voltage fluctuation suppression strategy and effectively reduce the risk of grid-trip accidents caused by voltage fluctuations.

[0041] Among them, in one embodiment of the present application, the grid connection point voltage at the rated output of the wind turbine in the power system is obtained, including: collecting the rated active power and rated reactive power during the operation of the wind turbine; using the rated active power, rated reactive power and the equivalent impedance of the target external power grid to determine the grid connection point voltage at the rated output of the wind turbine in the power system.

[0042] In the actual implementation process, the embodiment of the present application can calculate the grid connection point voltage of the wind turbine in the normal operating state (i.e., rated output) according to the equivalent impedance of the external power grid and the rated active power and rated reactive power collected during the operation of the wind turbine, and obtain it by solving the one-dimensional quadratic power flow equation of formula (1), that is:

[0043]

[0044] Among them, U is the voltage at the grid connection point of the wind turbine; P is the rated active power generated by the wind turbine; Q is the rated reactive power generated by the wind turbine; E is the equivalent potential of the grid; R is the equivalent resistance of the grid; and X is the equivalent reactance of the grid.

[0045] In step S102, when it is detected that the grid connection point voltage is less than or equal to the preset voltage, the transient voltage fluctuation suppression strategy of the power system is activated to calculate the maximum active power and minimum reactive power output by the wind turbine to meet the preset voltage fluctuation suppression conditions.

[0046] In the embodiment of the present application, the preset voltage fluctuation suppression condition is a condition for suppressing the voltage fluctuation caused by repeated low voltage ride-through.

[0047] It can be understood that the embodiment of the present application can activate the transient voltage fluctuation suppression strategy of the power system when it is detected that the grid connection point voltage is less than or equal to the voltage threshold for the wind turbine to enter low voltage ride-through, so as to calculate the maximum active power and minimum reactive power output by the wind turbine to meet the voltage fluctuation suppression conditions, thereby effectively enhancing the low voltage ride-through capability of the wind turbine and reducing the risk of grid-trip accidents caused by voltage fluctuations.

[0048] For example, as shown in the following formula, when the transient voltage fluctuation suppression signal Flag of the wind turbine generator set is 1, the transient voltage fluctuation suppression strategy is activated, otherwise the transient voltage fluctuation suppression strategy is not activated:

[0049]

[0050] Among them, U lim is the threshold for the wind turbine to enter low-breakthrough, and Flag is the transient voltage fluctuation suppression signal of the wind turbine.

[0051] Next, the embodiment of the present application can calculate the maximum active power value and the minimum reactive power value that can be output by the wind turbine to suppress voltage fluctuations to ensure economy. The calculation formula is as follows:

[0052] Q min =minQ op

[0053]

[0054] Among them, ΔU is the transient voltage fluctuation value of the wind turbine; P op , Q op are respectively the active power and reactive power generated by the wind turbine; P max , Q min They are respectively the maximum active power and minimum reactive power that the wind turbine grid-side converter can output.

[0055] In addition, in the embodiment of the present application, when Flag is 1, the active power reference value of the grid-side converter can be modified to P max , the reactive power reference value is changed to Q min By reasonably adjusting the reference values ​​of active and reactive power, the unloading circuit can be avoided from continuous operation, thereby preventing it from exceeding its thermal stability limit, reducing the risk of grid disconnection, and improving the stability of the power system.

[0056] In step S103, based on the maximum active power and the minimum reactive power, the pitch angle adjustment value of the wind turbine and the generator speed reference value are determined, so that the pitch angle of the wind turbine is adjusted by using the pitch angle adjustment value, and based on the generator speed reference value, the grid-side converter of the wind turbine is switched from the constant power control mode to the DC voltage control mode to suppress transient voltage fluctuations in the power system.

[0057] It can be understood that the embodiment of the present application can determine the pitch angle adjustment value of the wind turbine and the generator speed reference value based on the maximum active power and the minimum reactive power. For example, according to the functional relationship between the maximum wind energy utilization coefficient and the speed and pitch angle, the output power P of the wind turbine under maximum power tracking corresponding to different pitch angles under maximum power tracking can be obtained. MPPT and the generator speed reference value ωop ,Right now:

[0058] C pmax =maxC p

[0059]

[0060] Among them, C p is the wind energy utilization coefficient; ω is the actual speed of the generator; β is the pitch angle; C pmax is the maximum wind energy utilization coefficient.

[0061] P MPPT =f2[C pmax (β,ω op ),ω op ] (6)

[0062] Among them, P MPPT is the maximum output power of the wind turbine, ω op It is the reference value of the generator speed corresponding to the maximum output power of the wind turbine.

[0063] Next, the embodiment of the present application can determine the pitch angle adjustment value of the wind turbine generator set and the generator speed reference value according to the maximum output power, so as to adjust the pitch angle of the wind turbine generator set using the pitch angle adjustment value. For example, let P MPPT is the maximum output power P obtained in the above steps max , the corresponding pitch angle setting value is:

[0064] β op =f2 -1 (P max ) (7)

[0065] Among them, β op It is the pitch angle setting value corresponding to the maximum output power of the wind turbine.

[0066] When Flag is 1, the pitch angle of the wind turbine is adjusted to β op , by setting the pitch angle to β op , the input power of the wind turbine can be reduced to reduce the energy accumulation of the machine side input.

[0067] Secondly, the embodiment of the present application can be based on the generator speed reference value ω op , the grid-side converter of the wind turbine in the following steps is switched from the constant power control mode to the DC voltage control mode to suppress transient voltage fluctuations in the power system, which can avoid repeated switching of the DC unloading chopper circuit, reduce heat accumulation, and ensure the thermal stability of the equipment.

[0068] Among them, in one embodiment of the present application, based on the generator speed reference value, the grid-side converter of the wind turbine set is switched from the constant power control mode to the DC voltage control mode, including: collecting the actual speed of the generator in the wind turbine set; detecting whether the difference between the actual speed of the generator and the generator speed reference value is less than the preset speed value; when it is detected that the difference between the actual speed of the generator and the generator speed reference value is less than the preset speed value, switching the grid-side converter of the wind turbine set from the constant power control mode to the DC voltage control mode.

[0069] For example, the embodiment of the present application can collect the actual speed ω of the generator in the wind turbine group, and when it is detected that the actual speed ω of the generator is close to the reference speed value ω of the generator op , that is, the actual generator speed ω and the generator speed reference value ω op The difference is less than the threshold ω lim In this embodiment of the present application, the grid-side converter control can be adjusted from constant power control to DC voltage control, wherein the formula for switching DC voltage control is:

[0070] I dref =k p (U dcref -U dc )+k i ∫(U dcref -U dc )dt |ω-ω op |<ω lim (8)

[0071] Among them, ω op is the generator speed reference value corresponding to the maximum output power of the wind turbine; ω is the actual generator speed; ω lim is the threshold of the difference between the actual speed of the generator and the reference speed; I dref is the active reference value of the grid-side converter; k p , k i are the proportional and integral coefficients of constant DC voltage control respectively; U dcref is the DC voltage reference value; U dc is the actual value of DC voltage.

[0072] Therefore, the embodiment of the present application can suppress the voltage fluctuation caused by repeated low voltage ride-through, and significantly improve the operational stability of the power grid. In other words, the embodiment of the present application can ensure that the wind turbines always remain in the grid-connected state during the process of grid voltage drop and recovery, and can ensure that the wind turbines no longer repeatedly enter low voltage ride-through, greatly reducing the risk of off-grid accidents caused by voltage fluctuations.

[0073] For example, Figure 2As shown, the working principle of the embodiment of the present application is described in detail below with a specific embodiment.

[0074] Step S201: Calculate the grid connection point voltage U at the rated output of the wind turbine generator system.

[0075] Step S202: Determine whether the grid connection point voltage is less than or equal to the voltage threshold, that is, determine whether the grid connection point voltage is less than or equal to the voltage threshold for the wind turbine to enter low-voltage breakover. When the grid connection point voltage is less than or equal to the voltage threshold for the wind turbine to enter low-voltage breakover, execute step S203, otherwise execute step S204.

[0076] Step S203: Flag=1, start the transient voltage fluctuation suppression strategy.

[0077] Step S204: Flag=0, the suppression strategy is not started.

[0078] Step S205: Calculate the maximum active power and minimum reactive power P that the wind turbine can generate to suppress voltage fluctuations max , Q min .

[0079] Step S206: Modify the active and reactive reference values ​​of the grid-side converter to be P max , Q min .

[0080] Step S207: Calculate the wind turbine input power as P max The corresponding pitch angle adjustment value β op and the generator speed reference value ω op .

[0081] Step S208: Determine whether the actual generator speed ω is close to the speed reference value ω op , when the actual generator speed ω is not close to the generator speed reference value ω op If yes, execute step S209; otherwise, execute step S210.

[0082] Step S209: Continue to detect the actual generator speed ω.

[0083] Step S210: changing the grid-side converter back to the DC voltage control mode, that is, switching the grid-side converter of the wind turbine generator set from the constant power control mode to the DC voltage control mode, so as to suppress transient voltage fluctuations of the power system.

[0084] For example, Figure 3As shown in the figure, for a high proportion of renewable energy transmission lines, a schematic diagram of the suppression of transient voltage fluctuations after a line is cut off due to a fault, the suppression strategy can be started according to the transient voltage fluctuation suppression criterion, and then the maximum active power and minimum reactive power at which the wind turbine no longer enters the low-breakthrough are calculated and used as the reference value input of the grid-side converter, and then the pitch angle of the wind turbine is adjusted to match the power input and output of the wind turbine, and finally, when the generator speed is close to the reference value, the grid-side converter is adjusted back to the DC voltage control to avoid the continuous action of the unloading chopper circuit of the wind turbine, thereby effectively reducing the risk of off-grid accidents caused by voltage fluctuations.

[0085] According to the method for suppressing transient voltage fluctuations in a dual-high power system proposed in the embodiment of the present application, when it is detected that the grid connection point voltage under the rated output of the wind turbine in the power system is less than or equal to a certain voltage threshold, the transient voltage fluctuation suppression strategy of the power system can be activated to calculate the maximum active power and minimum reactive power output by the wind turbine to meet the voltage fluctuation suppression conditions, and then determine the pitch angle adjustment value and the generator speed reference value of the wind turbine, so as to adjust the pitch angle of the wind turbine using the pitch angle adjustment value, and switch the grid-side converter of the wind turbine from the constant power control mode to the DC voltage control mode based on the generator speed reference value, so as to suppress transient voltage fluctuations in the power system, effectively prevent wind turbine disconnection events, and improve the safety and stability of the power system. Thus, the problems that the voltage fluctuations caused by repeated low penetration cannot be suppressed in the related technology, which has the risk of causing disconnection and endangers the safety and stability of the power system are solved.

[0086] Next, a device for suppressing transient voltage fluctuations in a dual-high power system proposed in accordance with an embodiment of the present application will be described with reference to the accompanying drawings.

[0087] Figure 4 It is a block diagram of a device for suppressing transient voltage fluctuations in a dual-high power system according to an embodiment of the present application.

[0088] like Figure 4 As shown, the device 10 for suppressing transient voltage fluctuations in a dual-high power system includes: an acquisition module 100 , a processing module 200 and a control module 300 .

[0089] Specifically, the acquisition module 100 is used to acquire the grid connection point voltage at the rated output of the wind turbine in the power system, and detect whether the grid connection point voltage is less than or equal to a preset voltage.

[0090] The processing module 200 is used to activate the transient voltage fluctuation suppression strategy of the power system when it is detected that the grid connection point voltage is less than or equal to the preset voltage, so as to calculate the maximum active power and minimum reactive power output by the wind turbine to meet the preset voltage fluctuation suppression conditions.

[0091] The control module 300 is used to determine the pitch angle adjustment value and the generator speed reference value of the wind turbine group based on the maximum active power and the minimum reactive power, so as to adjust the pitch angle of the wind turbine group using the pitch angle adjustment value, and switch the grid-side converter of the wind turbine group from the constant power control mode to the DC voltage control mode based on the generator speed reference value, so as to suppress transient voltage fluctuations in the power system.

[0092] Optionally, in one embodiment of the present application, the acquisition module 100 includes: a first acquisition unit and a determination unit.

[0093] The first acquisition unit is used to acquire the rated active power and rated reactive power during the operation of the wind turbine.

[0094] The determination unit is used to determine the grid connection point voltage at the rated output of the wind turbine in the power system by using the rated active power, the rated reactive power and the equivalent impedance of the target external power grid.

[0095] Optionally, in one embodiment of the present application, the control module 300 includes: a second acquisition unit, a detection unit and a processing unit.

[0096] The second acquisition unit is used to acquire the actual rotation speed of the generator in the wind turbine.

[0097] A detection unit, used to detect whether a difference between an actual rotation speed of the generator and a reference value of the rotation speed of the generator is less than a preset rotation speed value;

[0098] The processing unit is used to switch the grid-side converter of the wind turbine generator from a constant power control mode to a DC voltage control mode when it is detected that the difference between the actual speed of the generator and the reference speed value of the generator is less than a preset speed value.

[0099] Optionally, in one embodiment of the present application, the calculation formula of the grid connection point voltage is:

[0100]

[0101] Among them, U is the voltage at the grid connection point of the wind turbine; P is the rated active power generated by the wind turbine; Q is the rated reactive power generated by the wind turbine; E is the equivalent potential of the grid; R is the equivalent resistance of the grid; and X is the equivalent reactance of the grid.

[0102] Optionally, in one embodiment of the present application, the formula for switching DC voltage control is:

[0103] I dref =k p (U dcref -U dc )+k i ∫(U dcref -Udc )dt |ω-ω op |<ω lim (9)

[0104] Among them, ω op is the generator speed reference value corresponding to the maximum output power of the wind turbine; ω is the actual generator speed; ω lim is the threshold of the difference between the actual speed of the generator and the reference speed; I dref is the active reference value of the grid-side converter; k p , k i are the proportional and integral coefficients of constant DC voltage control respectively; U dcref is the DC voltage reference value; U dc is the actual value of DC voltage.

[0105] It should be noted that the above explanation of the embodiment of the method for suppressing transient voltage fluctuations in a dual-high power system is also applicable to the device for suppressing transient voltage fluctuations in a dual-high power system of this embodiment, and will not be repeated here.

[0106] According to the device for suppressing transient voltage fluctuations in a dual-high power system proposed in the embodiment of the present application, when it is detected that the grid connection point voltage under the rated output of the wind turbine in the power system is less than or equal to a certain voltage threshold, the transient voltage fluctuation suppression strategy of the power system can be activated to calculate the maximum active power and minimum reactive power output by the wind turbine to meet the voltage fluctuation suppression conditions, and then determine the pitch angle adjustment value and the generator speed reference value of the wind turbine, so as to adjust the pitch angle of the wind turbine using the pitch angle adjustment value, and switch the grid-side converter of the wind turbine from the constant power control mode to the DC voltage control mode based on the generator speed reference value, so as to suppress transient voltage fluctuations in the power system, effectively prevent wind turbine disconnection events, and improve the safety and stability of the power system. Thus, the problems that the voltage fluctuations caused by repeated low penetration cannot be suppressed in the related technology, which has the risk of causing disconnection and endangers the safety and stability of the power system are solved.

[0107] Figure 5 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0108] A memory 501 , a processor 502 , and a computer program stored in the memory 501 and executable on the processor 502 .

[0109] When the processor 502 executes the program, the method for suppressing transient voltage fluctuations in the dual-high power system provided in the above embodiment is implemented.

[0110] Furthermore, the electronic device further comprises:

[0111] The communication interface 503 is used for communication between the memory 501 and the processor 502 .

[0112] The memory 501 is used to store computer programs that can be executed on the processor 502 .

[0113] The memory 501 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0114] If the memory 501, the processor 502 and the communication interface 503 are implemented independently, the communication interface 503, the memory 501 and the processor 502 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0115] Optionally, in a specific implementation, if the memory 501, the processor 502 and the communication interface 503 are integrated on a chip, the memory 501, the processor 502 and the communication interface 503 can communicate with each other through an internal interface.

[0116] The processor 502 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0117] This embodiment also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned method for suppressing transient voltage fluctuations in a dual-high power system.

[0118] This embodiment also provides a computer program product, including a computer program, which, when executed, is used to implement the above method for suppressing transient voltage fluctuations in a dual-high power system.

[0119] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0120] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0121] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0122] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways as necessary and then storing it in a computer memory.

[0123] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one or a combination of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0124] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0125] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0126] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for suppressing transient voltage fluctuations in a dual-high power system, characterized in that: The following steps are involved: Obtaining the grid connection point voltage at the rated output of the wind turbine in the power system, and detecting whether the grid connection point voltage is less than or equal to a preset voltage; When it is detected that the grid connection point voltage is less than or equal to the preset voltage, the transient voltage fluctuation suppression strategy of the power system is activated to calculate the maximum active power and the minimum reactive power output by the wind turbine generator set to meet the preset voltage fluctuation suppression condition; Based on the maximum active power and the minimum reactive power, the pitch angle adjustment value and the generator speed reference value of the wind turbine set are determined, so that the pitch angle of the wind turbine set is adjusted using the pitch angle adjustment value, and based on the generator speed reference value, the grid-side converter of the wind turbine set is switched from a constant power control mode to a DC voltage control mode to suppress transient voltage fluctuations of the power system.

2. The method according to claim 1, characterized in that The obtaining of the grid connection point voltage at the rated output of the wind turbine generator set in the power system includes: Collecting the rated active power and rated reactive power of the wind turbine during operation; The grid connection point voltage at the rated output of the wind turbine generator set in the power system is determined by using the rated active power, the rated reactive power and the equivalent impedance of the target external power grid.

3. The method according to claim 1, characterized in that The method of switching the grid-side converter of the wind turbine generator set from a constant power control mode to a DC voltage control mode based on the generator speed reference value includes: Collecting the actual rotation speed of the generator in the wind turbine; Detecting whether a difference between an actual rotation speed of the generator and a reference value of the rotation speed of the generator is less than a preset rotation speed value; When it is detected that the difference between the actual rotation speed of the generator and the generator rotation speed reference value is less than the preset rotation speed value, the grid-side converter of the wind turbine set is switched from the constant power control mode to the DC voltage control mode.

4. The method according to claim 1, characterized in that: The calculation formula of the grid connection point voltage is: Among them, U is the voltage at the grid connection point of the wind turbine; P is the rated active power generated by the wind turbine; Q is the rated reactive power generated by the wind turbine; E is the equivalent potential of the grid; R is the equivalent resistance of the grid; and X is the equivalent reactance of the grid.

5. The method according to claim 1, characterized in that: The formula for switching DC voltage control is: A dref =k p (HE dcref -HE dc )+k i ∫(U dcref -HE dc )dt|ω-ω op |<ω lim Among them, ω op is the generator speed reference value corresponding to the maximum output power of the wind turbine; ω is the actual generator speed; ω lim is the threshold of the difference between the actual speed of the generator and the reference speed; I dref is the active reference value of the grid-side converter; k p , k i are the proportional and integral coefficients of constant DC voltage control respectively; U dcref is the DC voltage reference value; U dc is the actual value of DC voltage.

6. A device for suppressing transient voltage fluctuations in a dual-high power system, characterized in that: include: An acquisition module is used to acquire the grid connection point voltage at the rated output of the wind turbine in the power system, and detect whether the grid connection point voltage is less than or equal to a preset voltage; A processing module, configured to activate a transient voltage fluctuation suppression strategy of the power system when detecting that the grid connection point voltage is less than or equal to the preset voltage, so as to calculate the maximum active power and the minimum reactive power output by the wind turbine generator set to meet the preset voltage fluctuation suppression condition; A control module is used to determine the pitch angle adjustment value and the generator speed reference value of the wind turbine group based on the maximum active power and the minimum reactive power, so as to adjust the pitch angle of the wind turbine group using the pitch angle adjustment value, and switch the grid-side converter of the wind turbine group from a constant power control mode to a DC voltage control mode based on the generator speed reference value, so as to suppress transient voltage fluctuations of the power system.

7. The device according to claim 6, characterized in that The acquisition module comprises: A first collection unit is used to collect the rated active power and rated reactive power of the wind turbine during operation; A determination unit is used to determine the grid connection point voltage at the rated output of the wind turbine in the power system by using the rated active power, the rated reactive power and the equivalent impedance of the target external power grid.

8. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for suppressing transient voltage fluctuations in a dual-high power system as described in any one of claims 1 to 5.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the method for suppressing transient voltage fluctuations in a dual-high power system as described in any one of claims 1-5.

10. A computer program product, comprising a computer program, characterized in that The computer program is executed by a processor to implement the method for suppressing transient voltage fluctuations in a dual-high power system as described in any one of claims 1-5.

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