Adaptive damping control method and device for wind power subsynchronous oscillation

Abstract

The embodiment of the present application provides a kind of adaptive damping control method and device for wind power subsynchronous oscillation, the method comprises: according to the output voltage of wind turbine or wind farm in wind power grid-connected system, the subsynchronous component of wind power subsynchronous oscillation is obtained;According to time constant and damping control gain, the subsynchronous component is phase-shifted and gain-adjusted processing, to obtain current reference signal, wherein the time constant is calculated in real time by the frequency of the subsynchronous component, and the damping control gain is calculated in real time according to the amplitude of the subsynchronous component;The current reference signal is input into the current transformer, to obtain the subsynchronous frequency current, and the subsynchronous frequency current is input into the wind power grid-connected system, to be used for inhibiting wind power subsynchronous oscillation.The embodiment of the present application achieves the goal of adaptive inhibition of wind power subsynchronous oscillation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system safety and stability control, and particularly relates to an adaptive damping control method and device for wind power subsynchronous oscillation. BACKGROUND

[0002] The dynamic interaction between grid-connected wind turbines and AC / DC power grids or other power electronic devices can cause new subsynchronous oscillation (SSO) problems, which are also referred to as subsynchronous control interaction (SSCI) or subsynchronous interaction (SSI) in some documents. Such SSO problems can cause equipment damage, stability destruction, power generation loss and other power quality problems, and seriously threaten the safety of the equipment and the stability of the system, which has become a bottleneck factor restricting the efficient consumption of wind power and a major technical problem faced by the current power industry. Therefore, it is of great practical significance to study the suppression of wind power SSO.

[0003] Existing SSO suppression methods can be roughly divided into two categories: wind turbine side methods and wind farm station side methods. The wind turbine side methods include adjusting the control parameters of the wind turbine converter (WTC), adding subsynchronous damping controllers (SSDC) in the grid-side converter (GSC) and rotor-side converter (RSC) controllers, or using more advanced nonlinear control structures. However, these methods have some shortcomings: the adjustment of the control parameters of the WTC may increase the risk of low-voltage ride-through (LVRT) problems; adding SSDC in the GSC / RSC control loop requires upgrading the controllers of all wind turbines, which is a considerable challenge for large-scale wind farms that have been put into operation; and the design and implementation of nonlinear control are too complex, and are usually less used in engineering. Generally, simple proportional-integral (PI) controllers are more commonly used in actual engineering. If the wind turbine side suppression method is used, all wind turbines usually need to be tested multiple times for grid connection, so these schemes are more suitable for application in the design stage of wind turbines.

[0004] On the other hand, the wind farm side method provides a system level solution for SSO suppression, such control methods include: additional SSDC of flexible ac transmission system (FACTS) device, high voltage dc (HVDC) converter and special shunt voltage-sourced converter (S-VSC). Among them, FACTS and HVDC converter are generally designed to work at the rated frequency of the system, and may encounter DC voltage fluctuation if used for lower frequency oscillation damping (such as 6-9 Hz in GuYuan system of Hebei), and this solution is expensive, and only in the case that the system has installed FACTS or HVDC controller, it is more economical; the use of special S-SVC can solve the problems of DC voltage fluctuation and cost. In addition, the operating conditions in the actual system are extremely complex and have strong time-varying nature, and under different operating conditions and disturbed conditions in the same system, the characteristics (frequency and amplitude) of the subsynchronous oscillation may be different. The offline design method usually needs to determine the oscillation characteristics and system operating conditions in advance, which is not flexible enough in actual application and cannot adapt to the changes of the system well.

[0005] Therefore, there is an urgent need for an adaptive damping control method and device for wind power subsynchronous oscillation to solve the above problems. SUMMARY

[0006] In view of the problems in the prior art, the embodiments of the present application provide an adaptive damping control method and device for wind power subsynchronous oscillation.

[0007] In a first aspect, the embodiments of the present application provide an adaptive damping control method for wind power subsynchronous oscillation, comprising:

[0008] According to the output voltage of the wind turbine or the wind farm in the wind power grid-connected system, the subsynchronous component of the wind power subsynchronous oscillation is obtained;

[0009] According to the time constant and the damping control gain, the subsynchronous component is phase-shifted and gain-adjusted to obtain a current reference signal, wherein the time constant is calculated in real time according to the frequency of the subsynchronous component, and the damping control gain is calculated in real time according to the amplitude of the subsynchronous component;

[0010] The current reference signal is input into the converter to obtain a subsynchronous frequency current, and the subsynchronous frequency current is input into the wind power grid-connected system to suppress the wind power subsynchronous oscillation.

[0011] Further, before obtaining the subsynchronous component of the wind power subsynchronous oscillation according to the output voltage of the wind turbine or the wind farm in the wind power grid-connected system, the method further comprises:

[0012] filtering and preprocessing the output current of the wind turbine or the wind farm in the wind power grid-connected system, and performing windowed fast Fourier transform processing on the filtered and preprocessed output current to obtain the frequency and amplitude of the subsynchronous component;

[0013] judging the wind power subsynchronous oscillation according to the frequency and amplitude of the subsynchronous component, and if a preset wind power subsynchronous oscillation condition is met, judging that the oscillation caused by the subsynchronous component is wind power subsynchronous oscillation to suppress the wind power subsynchronous oscillation.

[0014] Further, after filtering and preprocessing the output current of the wind turbine or the wind farm in the wind power grid-connected system, and performing windowed fast Fourier transform processing on the filtered and preprocessed output current to obtain the frequency and amplitude of the subsynchronous component, the method further comprises:

[0015] correcting the frequency and amplitude of the subsynchronous component by a three-point phasor correction algorithm to judge the wind power subsynchronous oscillation according to the corrected frequency and amplitude of the subsynchronous component.

[0016] Further, the obtaining the subsynchronous component of the wind power subsynchronous oscillation according to the output voltage of the wind turbine or the wind farm in the wind power grid-connected system comprises:

[0017] converting the output voltage into secondary voltage by a voltage transformer;

[0018] inputting the secondary voltage into a fundamental band-stop filter, a supersynchronous band-stop filter and a subsynchronous band-pass filter in sequence to obtain the subsynchronous component to suppress the wind power subsynchronous oscillation according to the subsynchronous component.

[0019] Further, the time constant is obtained by the following steps:

[0020] obtaining a damping control additional phase shift according to a preset total phase shift and a filter phase shift, the filter phase shift comprising a fundamental band-stop filter phase shift, a supersynchronous band-stop filter phase shift and a subsynchronous band-pass filter phase shift;

[0021] calculating the time constant by a Brent root-finding algorithm and a damping control additional phase shift formula.

[0022] Further, the calculating the time constant by the Brent root-finding algorithm and the damping control additional phase shift formula comprises:

[0023] The damping control additional phase shift formula is simplified to obtain a simplified damping control additional phase shift formula.

[0024]

[0025] The simplified damping control additional phase shift formula is:

[0026]

[0027] wherein, φ PS represents the damping control additional phase shift, φ = φ FIL + φ PS , φ represents a preset total phase shift, φ FIL represents a filter phase shift; T1 and T2 represent two time constants of a phase shifter, T represents a time constant to be calculated, T1 = -T, T2 = T; K represents a unit gain, K = 1; s is a Laplace operator, s = j2πf sub ; f sub represents a frequency of a subsynchronous component; n represents a preset number of phase shift links.

[0028] The simplified damping control additional phase shift formula is solved by using a Brent root-finding algorithm to obtain a numerical value of the time constant to be calculated.

[0029] Further, the preset wind power subsynchronous oscillation condition comprises:

[0030] If the frequency of the subsynchronous component is between a preset minimum frequency and a preset maximum frequency, and the amplitude of the subsynchronous component is greater than or equal to a preset amplitude threshold, it is determined that the oscillation corresponding to the subsynchronous component is wind power subsynchronous oscillation.

[0031] In a second aspect, an embodiment of the present application provides an adaptive damping control device for wind power subsynchronous oscillation, comprising:

[0032] A subsynchronous component real-time acquisition module is configured to obtain a subsynchronous component of wind power subsynchronous oscillation according to an output voltage of a wind turbine or a wind farm in a wind power grid-connected system.

[0033] An adaptive damping control module is configured to perform phase shift and gain adjustment processing on the subsynchronous component according to a time constant and a damping control gain, to obtain a current reference signal, wherein the time constant is calculated in real time according to the frequency of the subsynchronous component, and the damping control gain is calculated in real time according to the amplitude of the subsynchronous component.

[0034] A subsynchronous oscillation suppression module is configured to input the current reference signal into a converter to obtain a subsynchronous frequency current, and input the subsynchronous frequency current into the wind power grid-connected system to suppress wind power subsynchronous oscillation.

[0035] In a third aspect, an electronic device is provided, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the method provided in the first aspect when executing the program.

[0036] In a fourth aspect, a non-transitory computer readable storage medium is provided, which stores a computer program, and the computer program, when executed by a processor, implements the steps of the method provided in the first aspect.

[0037] The adaptive damping control method and device for wind power subsynchronous oscillation provided by the embodiments of the present application can achieve the goal of adaptive suppression of wind power subsynchronous oscillation by using the three-phase voltage and current of a wind turbine or a wind farm as feedback input, detecting the subsynchronous oscillation information (frequency and amplitude) in the signal, and adaptively adjusting the control parameters, and then controlling the converter to output a current of a corresponding frequency to be injected into the point of common coupling of the wind farm and the power grid. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0039] Figure 1 The flowchart of the adaptive damping control method for wind power subsynchronous oscillation provided by the embodiments of the present application is shown in the figure.

[0040] Figure 2 The overall flowchart of the adaptive damping control method for wind power subsynchronous oscillation provided by the embodiments of the present application is shown in the figure.

[0041] Figure 3 The structural diagram of the converter provided by the embodiments of the present application is shown in the figure.

[0042] Figure 4 The system diagram of the wind farm in the source region after using the adaptive damping control method provided by the embodiments of the present application is shown in the figure.

[0043] Figure 5 The current diagram of using and not using the adaptive damping control method for wind power subsynchronous oscillation provided by the embodiments of the present application is shown in the figure.

[0044] Figure 6 The real-time identification result of the subsynchronous component frequency and the time constant result schematic diagram provided by the embodiment of the present application;

[0045] Figure 7 The input and output schematic diagram of the phase-shifting link of the adaptive damping control method for wind power subsynchronous oscillation provided by the embodiment of the present application;

[0046] Figure 8 The current schematic diagram of the converter injected into the wind power grid-connected system provided by the embodiment of the present application;

[0047] Figure 9 The structure schematic diagram of the adaptive damping control device for wind power subsynchronous oscillation provided by the embodiment of the present application;

[0048] Figure 10 The electronic device structure schematic diagram provided by the embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0050] The existing SSO suppression methods mainly include wind turbine side method and wind farm side method, and both methods have some deficiencies. If the wind turbine side suppression method is used, all wind turbines need to be tested multiple times, so this scheme is more suitable for application in the design stage of wind turbines. The wind farm side method provides a system-level solution for SSO suppression. However, in the actual system, the operating conditions are extremely complex and have strong time-varying characteristics. In the same system, the characteristics (frequency and amplitude) of subsynchronous oscillation may be different under different operating conditions and disturbance conditions. The offline design method usually needs to determine the oscillation characteristics and system operating conditions in advance, and is not flexible enough in actual application and cannot adapt to the changes of the system well. Therefore, the embodiment of the present application proposes an adaptive damping control (ASDC) method and device for wind power subsynchronous oscillation. It should be noted that the three-phase voltage and current of the wind turbine are used as feedback input for illustration.

[0051] Figure 1 The flowchart schematic diagram of the adaptive damping control method for wind power subsynchronous oscillation provided by the embodiment of the present application is as follows:Figure 1 As shown in the figure, the embodiment of the present application provides an adaptive damping control method for wind power subsynchronous oscillation, comprising:

[0052] Step 101, obtaining the subsynchronous component of wind power subsynchronous oscillation according to the output voltage of wind turbine or wind farm in wind power grid-connected system.

[0053] In the embodiment of the present application, Figure 2 The overall flow chart of the adaptive damping control method for wind power subsynchronous oscillation provided by the embodiment of the present application can refer to Figure 2 As shown in the figure, first, it is judged whether wind power subsynchronous oscillation is generated in wind power grid-connected system, specifically, current transformer (CT) and analog to digital conversion (ADC) sub-modules are used to obtain the output current i a of wind turbine, and then pre-filtering is performed to remove high-frequency noise, supersynchronous and fundamental component. After pre-filtering, the current is subjected to windowed-fast Fourier transform (WFFT) and correction algorithm to calculate the frequency f sub and amplitude A sub of subsynchronous component. When the frequency and amplitude meet the corresponding threshold, it is determined that this oscillation is wind power subsynchronous oscillation, and the frequency and amplitude information of the subsynchronous component are used for subsequent adaptive damping control.

[0054] Further, after it is judged that wind power subsynchronous oscillation is generated in wind turbine, the subsynchronous component needs to be obtained in real time, specifically, the output voltage v abc of wind turbine is collected by potential transformer (PT), the subsynchronous component v SSO is obtained through filtering link, and is sent to subsequent adaptive damping control link, wherein the phase shift generated by the filter is φ FIL , and the phase shift parameter is output to subsequent adaptive calculation link of time constant.

[0055] Step 102, phase shifting and gain adjusting processing are performed on the subsynchronous component according to time constant and damping control gain to obtain current reference signal, wherein the time constant is calculated in real time according to the frequency of the subsynchronous component, and the damping control gain is calculated in real time according to the amplitude of the subsynchronous component.

[0056] In the embodiment of the present application, according to the frequency f sub of the subsynchronous component obtained by real-time acquisition and identification, the φFIL and calculate the additional phase shift φ needed by the damping control link PS , thereby outputting the calculated time constant T to the subsequent damping control link; at the same time, according to the amplitude A of the identified subsynchronous component obtained in real time sub , adjust the gain K of the damping control link G , that is, the damping control gain, and output the gain K to the subsequent adaptive damping control link. G

[0057] Further, according to the input phase-shifting link time constant T, the input voltage signal v is phase-shifted SSO and output to the gain link, multiplied by the gain K G , to obtain the current reference signal i o , which is output to the parallel converter.

[0058] Step 103: input the current reference signal into the converter to obtain a subsynchronous frequency current, and input the subsynchronous frequency current into the wind power grid-connected system for suppressing wind power subsynchronous oscillation.

[0059] In the embodiment of the present application, according to the input current reference signal i o , a subsynchronous frequency current i G injected into the point of common coupling of the wind power grid-connected system is generated, thereby realizing suppression of wind power subsynchronous oscillation. In the embodiment of the present application, a parallel voltage source type converter is used, which receives the current signal i o output by the adaptive damping control link, thereby generating a corresponding three-phase current i G and injecting it into the wind power grid-connected system at the point of common coupling. It should be noted that any converter capable of generating a current with the same frequency, amplitude and phase as the input signal can be used in the embodiment of the present application. Figure 3 The structure diagram of the converter provided in the embodiment of the present application is shown in Figure 3 , which is a chain structure, and the converter used in the embodiment of the present application is a Y-type wiring form with three bridge arms, each bridge arm being composed of n chain sub-modules in series, each bridge arm being connected to the system through a valve top converter reactor, each chain sub-module being equipped with a DC energy storage capacitor, cooperating with four groups of independent IGBT switching devices, and the frequency range and capacity of the current generated by the chain sub-module can be set according to the actual application scenario.

[0060] ​The adaptive damping control method for wind power subsynchronous oscillation provided by the embodiment of the application uses the three-phase voltage and current of a wind turbine or a wind farm as feedback input, detects the subsynchronous oscillation information (frequency and amplitude) in the signal, adaptively adjusts the control parameters, and then controls the converter to output the current of the corresponding frequency to the point of common coupling of the wind farm and the power grid, so as to achieve the goal of adaptively suppressing wind power subsynchronous oscillation.

[0061] On the basis of the above embodiment, before obtaining the subsynchronous component of the wind power subsynchronous oscillation according to the output voltage of the wind turbine or the wind farm in the wind power grid-connected system, the method further comprises:

[0062] filtering and preprocessing the output current of the wind turbine or the wind farm in the wind power grid-connected system, and performing windowed fast Fourier transform processing on the filtered and preprocessed output current to obtain the frequency and amplitude of the subsynchronous component;

[0063] judging the wind power subsynchronous oscillation according to the frequency and amplitude of the subsynchronous component, and if the preset wind power subsynchronous oscillation condition is met, judging that the oscillation caused by the subsynchronous component is wind power subsynchronous oscillation, so as to suppress the wind power subsynchronous oscillation.

[0064] In the embodiment of the application, reference can be made to Figure 2 As shown in the figure, the output current of the wind turbine is transformed into a certain proportion of small current i abc by a current transformer, and is sampled after analog-to-digital conversion processing, to obtain the current signal i a , which is then sent to a pre-filter to filter out the unnecessary frequency components in the input signal, such as high-frequency noise, supersynchronous and fundamental component.

[0065] Further, the pre-filtered current signal is subjected to windowed fast Fourier transform, so that the input signal only produces even integer frequency f int under a certain data window length. If the oscillation frequency of the input signal is odd, frequency leakage will occur.

[0066] On the basis of the above embodiment, after the filtering and preprocessing of the output current of the wind turbine or the wind farm in the wind power grid-connected system, and the windowed fast Fourier transform processing of the filtered and preprocessed output current to obtain the frequency and amplitude of the subsynchronous component, the method further comprises:

[0067] correcting the frequency and amplitude of the subsynchronous component by a three-point phasor correction algorithm, so as to judge the wind power subsynchronous oscillation according to the corrected frequency and amplitude of the subsynchronous component.

[0068] In this embodiment of the invention, when performing a windowed Fast Fourier Transform on the pre-filtered current signal, frequency leakage occurs if the oscillation frequency of the input signal is odd. To solve this problem, further signal correction is required. This embodiment of the invention corrects the initial values ​​of the frequency and amplitude of the subsynchronous component obtained in the above embodiments, which can be referred to... Figure 2 As shown, the correction algorithm includes a band-pass filter (BPF), a three-point phasor correction algorithm (3PPCA), and amplitude-phase compensation. Specifically, the band-pass filter extracts a coarse oscillation component from the integer frequency obtained by windowed fast Fourier transform, and then calculates the frequency and amplitude of the precise subsynchronous component by calculating three adjacent phasors according to the three-point phasor correction formula.

[0069] Based on the above embodiments, the preset wind power subsynchronous oscillation conditions include:

[0070] If the frequency of the subsynchronous component is between the preset minimum frequency and the preset maximum frequency, and the amplitude of the subsynchronous component is greater than or equal to the preset amplitude threshold, then it is determined that the oscillation corresponding to the subsynchronous component is a wind power subsynchronous oscillation.

[0071] In this embodiment of the invention, it is necessary to determine the frequency and amplitude of the subsynchronous component identified in real time, thereby identifying the oscillation in the wind turbine as wind power subsynchronous oscillation. Specifically, satisfying the preset wind power subsynchronous oscillation condition involves: the frequency f of the subsynchronous component obtained in real time... sub The frequency f of the subsynchronous component, which is located between the preset minimum and maximum frequencies, and is obtained in real time. sub Amplitude identification result A sub Greater than or equal to the preset amplitude threshold A th In this embodiment of the invention, A th The frequency f can be selected based on the amplitude of the fundamental component; if the oscillation is determined to be a subsynchronous oscillation, then the identified frequency f is... sub and amplitude information A sub Used in subsequent adaptive damping control.

[0072] Based on the above embodiments, obtaining the subsynchronous component of the wind power subsynchronous oscillation according to the output voltage of the wind turbine or wind farm in the wind power grid connection system includes:

[0073] The output voltage is converted into a secondary voltage using a voltage transformer.

[0074] The secondary voltage is sequentially input into a fundamental band elimination filter, a super-synchronous band elimination filter and a sub-synchronous band pass filter to obtain a sub-synchronous component, so as to inhibit the wind power sub-synchronous oscillation according to the sub-synchronous component.

[0075] In the embodiments of the present application, the voltage signal of the input wind turbine can be processed as shown in the figure to obtain the sub-synchronous component in real time, thereby providing an input signal for the damping control. Figure 2 The output voltage of the wind turbine is converted into a standard secondary voltage v abc by a voltage transformer, and then input into the fundamental band elimination filter to eliminate the fundamental frequency component, and then input into the super-synchronous band elimination filter to eliminate the super-synchronous frequency component, and finally input into the sub-synchronous band pass filter to extract the sub-synchronous component v sso . sso The sub-synchronous component v PS is sent to the subsequent adaptive damping control link.

[0076] On the basis of the above-mentioned embodiments, the time constant is obtained by the following steps:

[0077] According to the preset total phase shift and filter phase shift, the damping control additional phase shift is obtained, and the filter phase shift includes the fundamental band elimination filter phase shift, the super-synchronous band elimination filter phase shift and the sub-synchronous band pass filter phase shift.

[0078] The time constant is calculated by the Brent root-finding algorithm and the damping control additional phase shift formula.

[0079] On the basis of the above-mentioned embodiments, the time constant is calculated by the Brent root-finding algorithm and the damping control additional phase shift formula, including:

[0080] The damping control additional phase shift formula is simplified to obtain the simplified damping control additional phase shift formula, and the damping control additional phase shift formula is:

[0081]

[0082] The simplified damping control additional phase shift formula is:

[0083]

[0084] wherein, φ PS represents the damping control additional phase shift, φ = φ FIL + φ PS , φ represents the preset total phase shift, φ FIL represents the filter phase shift; T1 and T2 represent two time constants of the phase shifter, T represents the time constant to be calculated, T1 = -T, T2 = T; K represents a unit gain, K = 1; s is a Laplace operator, s = j2πf.sub ;f sub denotes the frequency of the subsynchronous component; n denotes the number of preset phase shift links, in the embodiment of the application, a typical value n=2 is selected;

[0085] The simplified damping control additional phase shift formula is solved by using the Brent root-finding algorithm to obtain the numerical value of the time constant to be calculated.

[0086] In the embodiment of the application, the input signal (i.e. the subsynchronous component) is subjected to phase shift and gain adjustment, thereby realizing damping control of wind power subsynchronous oscillation, wherein the parameters of the control link are obtained by online real-time calculation to realize adaptive control. Specifically, in the embodiment of the application, a typical transfer function of the damping control link is as follows:

[0087] G(s)=K G ·G PS (s);

[0088] Wherein, K G denotes the damping control gain, G PS denotes the transfer function of the phase shifter, in the embodiment of the application, the transfer function formula of the phase shifter is as follows:

[0089]

[0090] Wherein, K=1 is a unit gain, T1 and T2 are time constants of the phase shifter, and n denotes the number of preset phase shift links, by setting a suitable n, the phase shifter generates a suitable phase shift according to the given time constant.

[0091] Further, the gain link is to make the amplitude of the output signal meet the demand of the target system, therefore, the adaptive damping control link multiplies the phase-shifted signal by K G , thereby obtaining the output current reference signal.

[0092] Specifically, in the embodiment of the application, in order to realize adaptive suppression of wind power subsynchronous oscillation under different working conditions, the parameters of the damping control link need to be adaptively adjusted according to the system oscillation characteristics. The adaptive calculation of the time constant and the damping control gain is included.

[0093] I. Adaptive calculation of time constant

[0094] The adaptive damping control link needs to calculate the time constant according to the phase shift of the signal. The embodiment of the application considers the influence of the filtering process on the phase shift when the subsynchronous component is obtained, thereby calculating the total phase shift of the input wind turbine voltage signal through each link as follows:

[0095] φ=φ FIL +φ PS;

[0096] wherein φ FIL represents the phase shift of the filter when acquiring the sub-synchronous component, φ PS represents the additional phase shift of the adaptive damping control link; the total phase shift φ is set, wherein the total phase shift φ should be greater than 90° or less than -90°, so that the adaptive damping control link is equivalent to an inductive / capacitive reactance at the sub-synchronous frequency, thereby making the current output lead / lag the input (voltage).

[0097] Further, the phase shift φ FIL of the filter is the sum of the phase shifts of the fundamental band-stop filter, the super-synchronous band-stop filter and the sub-synchronous band-pass filter:

[0098] φ FIL = φ0+ φ sup + φ sub ;

[0099] wherein φ0represents the phase shift of the fundamental band-stop filter, φ sup represents the phase shift of the super-synchronous band-stop filter, φ sub represents the phase shift of the sub-synchronous band-pass filter, and are respectively represented as follows:

[0100]

[0101] wherein G Fund-BSF (s) represents the transfer function of the fundamental band-stop filter, G Sup-BSF (s) represents the transfer function of the super-synchronous band-stop filter, and G Sub-BPF (s) represents the transfer function of the sub-synchronous band-pass filter. In the embodiment of the present application, by calculating the appropriate time constant, the phase response φ PS of the required damping control link can be obtained, thereby obtaining the required total phase shift. The formula of the damping control additional phase shift φ PS is as follows:

[0102]

[0103] Substituting K=1, T1=-T and T2=T into the formula of the damping control additional phase shift φ PS and simplifying, the following can be obtained:

[0104]

[0105] wherein s is the Laplace operator, s=j2πf sub , and the above formula can be represented as:

[0106]

[0107] Since it is very difficult to directly solve the above equation, but since the root interval is known to be between 0 and 0.1, embodiments of the present application use the Brent root-finding method to calculate the time constant in real time, ensuring fast and accurate calculation of the phase shifter parameters, so that the solving process converges quickly. Finally, the calculated time constant value T is sent to the adaptive damping control link.

[0108] II. Adaptive calculation of damping control gain

[0109] The gain of the damping control link is adjusted according to the amplitude of the subsynchronous component identified in real time, and the current signal multiplied by the gain is output to the parallel voltage source type converter, and the gain is calculated as follows:

[0110]

[0111] wherein, represents the multiplier, which is determined by the amplitude of the subsynchronous component and the maximum capacity of the parallel voltage source type converter. Then, the calculated gain K G is sent to the subsequent adaptive damping control link.

[0112] In an embodiment of the present application, based on the adaptive damping control method for wind power subsynchronous oscillation provided by the embodiments of the present application, a case analysis is performed on the subsynchronous oscillation event of the wind farm in Guoyuan area. Figure 4 The system diagram of the wind farm in Guoyuan area provided by the embodiments of the present application after using the adaptive damping control method can be referred to as shown in Figure 4 The total number of doubly-fed induction generators is 2000, and the cumulative installed capacity is 3GW; the generated power is collected at Guoyuan substation through 220kV lines and transformers; it is transmitted to North China and Inner Mongolia power grid through 2 220 / 500kV step-up transformers; the Guoyuan-Hanhai (GH) and Guoyuan-Taiping (GT) transmission lines have 40% and 45% series compensation respectively, and the system has 58 subsynchronous oscillation events in one year; as shown in Figure 4 The embodiments of the present application plan to use the adaptive damping control method for wind power subsynchronous oscillation at the 220kV side of Guoyuan power transformer.

[0113] Specifically, a simulation model is established in PSCAD / EMTDC to reproduce a subsynchronous oscillation event that has occurred in Guoyuan wind power system, in the embodiments of the present application, the wind speed is 4m / s, and the affected wind turbine generators are 200, accounting for 10% of the total installed capacity, and the equivalent degree of series compensation is adjusted to a value that triggers subsynchronous oscillation. At t=0, three of the four sets of series compensation schemes have been put into use, and at t=5s, the fourth set of compensation is also online, triggering 9Hz unstable subsynchronous oscillation. Figure 5This is a current diagram illustrating the use of and non-use of the wind power subsynchronous oscillation adaptive damping control method in an embodiment of the present invention. Figure 5 (a) in the diagram is a schematic diagram of the measured current on the 220kV side of the Guyuan substation after the controller (i.e., the wind power subsynchronous oscillation adaptive damping control method) was put into operation. Figure 5 (b) in the diagram is a schematic diagram of the measured current on the 220kV side of the Guyuan substation before the controller (i.e., the wind power subsynchronous oscillation adaptive damping control method) was put into operation. Figure 5 As shown in (b), without the adaptive damping control method for wind power subsynchronous oscillations, the oscillation amplitude continuously increases; while for systems employing the adaptive damping control method for wind power subsynchronous oscillations (see reference...), the amplitude increases continuously. Figure 5 As shown in (a) of the present invention, the wind power subsynchronous oscillation adaptive damping control method provided in this embodiment can detect unstable oscillations and stabilize them relatively quickly. The frequency estimation algorithm detects the frequency and amplitude of the oscillations in about 0.75 seconds.

[0114] Furthermore, Figure 6 This is a schematic diagram illustrating the real-time identification results and time constant results of the subsynchronous component frequency provided in an embodiment of the present invention. The estimated oscillation frequency can be referenced... Figure 6 As shown in (a), the initial frequency identification algorithm detected an even integer frequency of 8 Hz. The correction stage quickly adjusted the frequency result to stabilize it to a more accurate value of approximately 9.3 Hz. To obtain the required phase shift at the measured subsynchronous frequency, the Brent root-finding method was used to calculate the corresponding time constant T of the control stage, as shown in (a). Figure 6 As shown in (b), when calculating the time constant T, the phase shift between the input and output of the phase shifting element is always maintained at the desired value (e.g., 80 degrees). Figure 7 This is a schematic diagram of the input and output of the phase-shifting stage in the adaptive damping control method for subsynchronous oscillations of wind power provided in this embodiment of the invention. The input and output of the phase-shifting stage can be referred to respectively. Figure 7 (a) and Figure 7 As shown in (b), both maintain a stable phase shift. Then, the gain circuit amplifies the output of the phase shift circuit to obtain the current reference signal. Figure 8 This is a schematic diagram of the current injected into the wind power grid-connected system by the converter according to an embodiment of the present invention, as shown below. Figure 8 As shown, as the oscillations decay, the current injected into the wind power grid-connected system by the converter also gradually decreases.

[0115] The adaptive damping control method for wind power subsynchronous oscillation provided by the embodiment of the present application is an online control scheme with high adaptability and good real-time performance, does not need to use frequency scanning or impedance analysis method in advance to improve the robustness of the damping controller, and does not need to perform optimal design of the controller parameters in advance. The identification method for wind power subsynchronous oscillation proposed by the present application ensures that the occurrence of subsynchronous oscillation and the frequency and amplitude of the subsynchronous component are quickly and accurately judged, can adapt to the changes of the system structure and operating conditions, and effectively suppresses the subsynchronous oscillation.

[0116] Figure 9 The structural schematic diagram of the adaptive damping control device for wind power subsynchronous oscillation provided by the embodiment of the present application is shown in Figure 9 The adaptive damping control device for wind power subsynchronous oscillation provided by the embodiment of the present application comprises a subsynchronous component real-time acquisition module 901, an adaptive damping control module 902 and a subsynchronous oscillation suppression module 903, wherein the subsynchronous component real-time acquisition module 901 is used to obtain the subsynchronous component of wind power subsynchronous oscillation according to the output voltage of a wind turbine or a wind farm in a wind power grid-connected system; the adaptive damping control module 902 is used to perform phase shift and gain adjustment processing on the subsynchronous component according to a time constant and a damping control gain, to obtain a current reference signal, wherein the time constant is obtained by real-time calculation of the frequency of the subsynchronous component, and the damping control gain is obtained by real-time calculation of the amplitude of the subsynchronous component; and the subsynchronous oscillation suppression module 903 is used to input the current reference signal into a converter to obtain a subsynchronous frequency current, and input the subsynchronous frequency current into the wind power grid-connected system, to suppress wind power subsynchronous oscillation.

[0117] The adaptive damping control device for wind power subsynchronous oscillation provided by the embodiment of the present application uses the three-phase voltage and current of a wind turbine or a wind farm as feedback input, adaptively adjusts the control parameters by detecting the subsynchronous oscillation information (frequency and amplitude) in the signal, and then controls the converter to output the current of the corresponding frequency to be injected into the point of common coupling of the wind farm and the power grid, so as to achieve the goal of adaptively suppressing wind power subsynchronous oscillation.

[0118] The device provided by the embodiment of the present application is used to execute the above-mentioned method embodiments, and the specific flow and detailed content are referred to the above-mentioned embodiments, which will not be described here.

[0119] Figure 10 The structural schematic diagram of the electronic device provided by the embodiment of the present application is shown in Figure 10The electronic device can include a processor 1001, a communications interface 1002, a memory 1003, and a communications bus 1004, wherein the processor 1001, the communications interface 1002, and the memory 1003 complete mutual communication through the communications bus 1004. The processor 1001 can call a logical instruction in the memory 1003 to execute the following method: obtaining a subsynchronous component of wind power subsynchronous oscillation according to an output voltage of a wind turbine or a wind farm in a wind power grid-connected system; performing phase shift and gain adjustment processing on the subsynchronous component according to a time constant and a damping control gain, to obtain a current reference signal, wherein the time constant is calculated in real time through a frequency of the subsynchronous component, and the damping control gain is calculated in real time according to an amplitude of the subsynchronous component; inputting the current reference signal into a converter to obtain a subsynchronous frequency current, and inputting the subsynchronous frequency current into the wind power grid-connected system to suppress the wind power subsynchronous oscillation.

[0120] In addition, the logical instruction in the memory 1003 described above can be implemented in the form of a software function unit and sold or used as an independent product, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0121] In another aspect, the embodiments of the present application also provide a non-transitory computer-readable storage medium, which stores a computer program. The computer program is executed by a processor to implement the adaptive damping control method for wind power subsynchronous oscillation provided by the above-mentioned embodiments, for example, including: obtaining a subsynchronous component of wind power subsynchronous oscillation according to an output voltage of a wind turbine or a wind farm in a wind power grid-connected system; performing phase shift and gain adjustment processing on the subsynchronous component according to a time constant and a damping control gain to obtain a current reference signal, wherein the time constant is calculated in real time through a frequency of the subsynchronous component, and the damping control gain is calculated in real time according to an amplitude of the subsynchronous component; inputting the current reference signal into a converter to obtain a subsynchronous frequency current, and inputting the subsynchronous frequency current into the wind power grid-connected system to suppress wind power subsynchronous oscillation.

[0122] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e., can be located in one place or distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiment scheme according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0123] From the above description of the embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software plus necessary universal hardware platforms, and of course can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of software products, which can be stored in a computer readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and include a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0124] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An adaptive damping control method for subsynchronous oscillations in wind power, characterized in that, include: Based on the output voltage of the wind turbine or wind farm in the wind power grid connection system, the subsynchronous component of the wind power subsynchronous oscillation is obtained. Based on the time constant and the damping control gain, the subsynchronous component is subjected to phase shifting and gain adjustment to obtain a current reference signal. The time constant is calculated in real time based on the frequency of the subsynchronous component, and the damping control gain is calculated in real time based on the amplitude of the subsynchronous component. The time constant is obtained through the following steps: Based on the preset total phase shift and filter phase shift, the additional phase shift for damping control is obtained. The filter phase shift includes the fundamental band-stop filter phase shift, the supersynchronous band-stop filter phase shift, and the subsynchronous bandpass filter phase shift. The time constant is calculated using the Brunt root-finding algorithm and the damped control additional phase shift formula. The current reference signal is input into the converter to obtain the subsynchronous frequency current, and the subsynchronous frequency current is input into the wind power grid-connected system to suppress wind power subsynchronous oscillation.

2. The adaptive damping control method for wind power subsynchronous oscillation according to claim 1, characterized in that, Before obtaining the subsynchronous component of the wind power subsynchronous oscillation based on the output voltage of the wind turbine or wind farm in the wind power grid-connected system, the method further includes: The output current of wind turbines or wind farms in the wind power grid-connected system is filtered and preprocessed, and then the preprocessed output current is processed by windowed fast Fourier transform to obtain the frequency and amplitude of the subsynchronous component. Based on the frequency and amplitude of the subsynchronous component, the subsynchronous oscillation of wind power is judged. If the preset subsynchronous oscillation condition of wind power is met, it is determined that the oscillation generated by the subsynchronous component is a subsynchronous oscillation of wind power, so as to suppress the subsynchronous oscillation of wind power.

3. The adaptive damping control method for wind power subsynchronous oscillation according to claim 2, characterized in that, After filtering and preprocessing the output current of the wind turbine or wind farm in the wind power grid-connected system, and performing windowed fast Fourier transform processing on the pre-filtered output current to obtain the frequency and amplitude of the subsynchronous component, the method further includes: The frequency and amplitude of the subsynchronous component are corrected using a three-point phasor correction algorithm, so as to determine the subsynchronous oscillation of wind power based on the corrected frequency and amplitude of the subsynchronous component.

4. The adaptive damping control method for wind power subsynchronous oscillation according to claim 1, characterized in that, The process of obtaining the subsynchronous component of wind power subsynchronous oscillation based on the output voltage of wind turbines or wind farms in the wind power grid-connected system includes: The output voltage is converted into a secondary voltage using a voltage transformer. The secondary voltage is sequentially input into the fundamental band-stop filter, the supersynchronous band-stop filter, and the subsynchronous band-pass filter to obtain the subsynchronous component, so as to suppress the subsynchronous oscillation of wind power.

5. The adaptive damping control method for wind power subsynchronous oscillation according to claim 1, characterized in that, The time constant is calculated using the Brent root-finding algorithm and the damped control additional phase shift formula, including: The damping control additional phase shift formula is simplified to obtain the simplified damping control additional phase shift formula: The simplified damping control additional phase shift formula is as follows: Where, φ PS This indicates the additional phase shift due to damping control, φ = φ FIL +φ PS φ represents the preset total phase shift. FIL T1 and T2 represent the phase shift of the filter; T1 and T2 represent the two time constants of the phase shifter, T represents the time constant to be calculated, T1 = -T, T2 = T; K represents the unity gain, K = 1; s represents the Laplace operator, s = j2πf sub ;f sub The frequency of the subsynchronous component is represented by ; n represents the number of preset phase-shifting elements; The simplified damping control additional phase shift formula is solved using the Brunt root-finding algorithm to obtain the value of the time constant to be calculated.

6. The adaptive damping control method for wind power subsynchronous oscillation according to claim 2, characterized in that, The preset wind power subsynchronous oscillation conditions include: If the frequency of the subsynchronous component is between the preset minimum frequency and the preset maximum frequency, and the amplitude of the subsynchronous component is greater than or equal to the preset amplitude threshold, then it is determined that the oscillation corresponding to the subsynchronous component is a wind power subsynchronous oscillation.

7. An adaptive damping control device for subsynchronous oscillations in wind power, characterized in that, include: The real-time acquisition module for subsynchronous components is used to obtain the subsynchronous components of wind power subsynchronous oscillation based on the output voltage of wind turbines or wind farms in the wind power grid-connected system. An adaptive damping control module is used to perform phase shifting and gain adjustment processing on the subsynchronous component based on a time constant and a damping control gain to obtain a current reference signal. The time constant is calculated in real time based on the frequency of the subsynchronous component, and the damping control gain is calculated in real time based on the amplitude of the subsynchronous component. The time constant is obtained through the following steps: Based on the preset total phase shift and filter phase shift, the additional phase shift for damping control is obtained. The filter phase shift includes the fundamental band-stop filter phase shift, the supersynchronous band-stop filter phase shift, and the subsynchronous bandpass filter phase shift. The time constant is calculated using the Brunt root-finding algorithm and the damped control additional phase shift formula. The subsynchronous oscillation suppression module is used to input the current reference signal into the converter to obtain the subsynchronous frequency current, and input the subsynchronous frequency current into the wind power grid-connected system to suppress wind power subsynchronous oscillation.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the adaptive damping control method for wind power subsynchronous oscillation as described in any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the adaptive damping control method for wind power subsynchronous oscillations as described in any one of claims 1 to 6.

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