Broadband oscillation suppression method and system based on new energy station impedance updating

Abstract

According to the broadband oscillation suppression method and system based on new energy station impedance updating, when the grid-connected voltage oscillation amplitude at an oscillation frequency point is larger than a voltage oscillation threshold value and / or the grid-connected current oscillation amplitude at the oscillation frequency point is larger than a current oscillation threshold value, the impedance vector of the new energy station at the oscillation frequency point is updated by using a set impedance angle; calculating an admittance vector of the broadband oscillation suppression device at an oscillation frequency point so as to update voltage and current suppression loop control parameters; grid-connected voltage is used as an input signal of a voltage suppression loop, and the voltage suppression loop outputs a first reference value of broadband oscillation suppression current; the difference value between the grid-connected current and the output current of the broadband oscillation suppression device serves as an input signal of a current suppression loop, and the current suppression loop outputs a second reference value of the broadband oscillation suppression current; taking the sum of the first reference value and the second reference value of the broadband oscillation suppression current as a broadband oscillation suppression current instruction; the problem that the single voltage oscillation quantity cannot be accurately extracted is avoided.

Description

Technical Field

[0001] The present invention belongs to the field of power electronics technology and broadband oscillation suppression, and in particular relates to a broadband oscillation adaptive suppression method and system based on new energy impedance update. Background Art

[0002] With the development of new power systems, large-scale power electronic equipment is continuously connected to the power grid, making the stability of the power system more complicated. In particular, small disturbance stability needs to focus on a wider frequency range, not just near the synchronous frequency. In recent years, broadband oscillation events have occurred many times, causing a large number of new energy units to trip and cut off the machine, affecting the safe and stable operation of the power grid.

[0003] Existing literature research shows that the emergence of broadband oscillation problems is closely related to the impedance characteristics of new energy units. The oscillation can be effectively suppressed by adjusting the control parameters of new energy units. However, due to the large scale of new energy units, adjusting the control parameters is time-consuming and labor-intensive. In practice, it is hoped that the oscillation problem can be solved by connecting an additional damping suppression device based on a power electronic converter in parallel without changing the original controller and its parameters of the system.

[0004] In the existing broadband oscillation suppression solutions based on impedance update, usually only voltage information is extracted as the input of the suppression strategy. The disadvantage of this method is that it is difficult to accurately extract effective information when the voltage oscillation is small. In addition, conventional suppression strategies generally only work for a certain frequency band and cannot be adjusted online according to the oscillation frequency, so the applicability is poor. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a wide-band oscillation suppression method and system based on impedance update of new energy stations, which can use both voltage and current as inputs of the suppression strategy, avoiding the problem that a single voltage oscillation quantity cannot be accurately extracted.

[0006] The present invention adopts the following technical solution.

[0007] The present invention proposes a broadband oscillation suppression method based on impedance update of a new energy station, comprising:

[0008] Obtaining the grid-connected voltage oscillation vector and the grid-connected current oscillation vector at the oscillation frequency point, and the output current oscillation vector of the wide-band oscillation suppression device at the oscillation frequency point, so as to calculate the impedance vector of the new energy station at the oscillation frequency point;

[0009] When the grid-connected voltage oscillation amplitude at the oscillation frequency point is greater than the set voltage oscillation threshold value and / or the grid-connected current oscillation amplitude at the oscillation frequency point is greater than the set current oscillation threshold value, the impedance vector of the new energy station at the oscillation frequency point is updated using the set impedance angle, and the impedance vector of the new energy station at the oscillation frequency point before the update and the impedance vector of the new energy station at the oscillation frequency point after the update are used to calculate the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point;

[0010] Using the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point, the control parameters of the voltage suppression loop are updated and then the voltage suppression loop is started; at the same time, using the admittance vector of the new energy field station at the oscillation frequency point before the update and the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point, the control parameters of the current suppression loop are updated and then the current suppression loop is started;

[0011] The grid-connected voltage is used as the input signal of the voltage suppression loop, and the voltage suppression loop outputs a first reference value of the wide-band oscillation suppression current; the difference between the grid-connected current and the output current of the wide-band oscillation suppression device is used as the input signal of the current suppression loop, and the current suppression loop outputs a second reference value of the wide-band oscillation suppression current; the sum of the first reference value and the second reference value of the wide-band oscillation suppression current is used as a wide-band oscillation suppression current instruction; the wide-band oscillation suppression device adjusts the output current according to the wide-band oscillation suppression current instruction.

[0012] Preferably, the impedance vector of the new energy station at the oscillation frequency point is calculated using the following relationship:

[0013]

[0014] In the formula, Z renew is the impedance vector of the new energy station at the oscillation frequency point, V pcc is the grid-connected voltage oscillation vector at the oscillation frequency point, is the grid-connected current oscillation vector at the oscillation frequency point, is the output current oscillation vector of the broadband oscillation suppression device at the oscillation frequency point, is the real part of the impedance vector of the new energy station at the oscillation frequency point, It is the imaginary part of the impedance vector of the new energy field station at the oscillation frequency point.

[0015] Preferably, the voltage oscillation threshold V is set TH The value range is [0.01~0.1], and the set current oscillation threshold I TH The value range is [0.05~0.2].

[0016] Preferably, the impedance vector of the new energy station at the oscillation frequency point is updated using the following relationship:

[0017]

[0018] In the formula, is the impedance vector of the updated new energy station at the oscillation frequency point, θ eq is the set impedance angle, θ eq The value range is [0, 90°];

[0019] The admittance vector of the broadband oscillation suppression device at the oscillation frequency point is calculated using the following relationship:

[0020]

[0021] In the formula, is the admittance vector of the broadband oscillation suppression device at the updated oscillation frequency point, is the admittance vector of the updated new energy station at the oscillation frequency point, is the admittance vector of the new energy station at the oscillation frequency point,

[0022] Preferably, the control parameters of the voltage suppression loop include: voltage phase shift angle, voltage proportional coefficient and voltage phase shift time constant;

[0023] The voltage phase shift angle and voltage proportional coefficient are determined by the following relationship:

[0024]

[0025] In the formula, θ PS_V is the voltage phase shift angle of the voltage suppression loop, θ SDC is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, K V is the voltage proportionality coefficient of the voltage suppression loop, is the modulus of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point;

[0026] The voltage phase shift time constant is determined by the following relationship:

[0027]

[0028] Where, T V is the voltage phase shift time constant, ω sso is the angular frequency at the oscillation frequency point.

[0029] Preferably, the control parameters of the current suppression loop include: current phase shift angle, current proportionality coefficient and current phase shift time constant;

[0030] The current phase shift angle and current proportionality coefficient are determined by the following relationship:

[0031]

[0032] In the formula, θ PS_I is the current phase shift angle of the current suppression loop, θ renew is the vector angle of the admittance vector of the new energy station at the oscillation frequency point, θ SDC is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, K I is the current proportionality coefficient of the current suppression loop, is the modulus of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, is the modulus of the admittance vector of the new energy station at the oscillation frequency point;

[0033] The current phase shift time constant is determined by the following relationship:

[0034]

[0035] Where, T I is the current phase shift time constant, ω sso is the angular frequency at the oscillation frequency point.

[0036] Preferably, the method further comprises: the broadband oscillation suppression device takes the moment of receiving the broadband oscillation suppression current instruction as the starting moment, and starting from the starting moment, samples the broadband oscillation current within W consecutive oscillation cycles, if the broadband oscillation current amplitude sampled within the wth oscillation cycle is satisfy: w∈[1,W], ζ is the divergence coefficient, then it is determined that the broadband oscillation current continues to diverge, and the broadband oscillation suppression device stops operating.

[0037] The present invention also proposes a broadband oscillation suppression system based on impedance update of a new energy station, comprising:

[0038] An adaptive adjustment module is used to obtain a grid-connected voltage oscillation vector and a grid-connected current oscillation vector at an oscillation frequency point, and an output current oscillation vector of a wide-band oscillation suppression device at an oscillation frequency point, so as to calculate an impedance vector of a new energy station at the oscillation frequency point; when the grid-connected voltage oscillation amplitude at the oscillation frequency point is greater than a set voltage oscillation threshold value and / or the grid-connected current oscillation amplitude at the oscillation frequency point is greater than a set current oscillation threshold value, the impedance vector of the new energy station at the oscillation frequency point is updated using a set impedance angle, and the impedance vector of the new energy station at the oscillation frequency point before the update and the impedance vector of the new energy station at the oscillation frequency point after the update are used to calculate the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point; the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point is used to update the control parameters of the voltage suppression loop and then start the voltage suppression loop; at the same time, the admittance vector of the new energy station at the oscillation frequency point before the update and the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point are used to update the control parameters of the current suppression loop and then start the current suppression loop;

[0039] A wide-band oscillation controller is used to use the grid-connected voltage as the input signal of the voltage suppression loop, and the voltage suppression loop outputs the first reference value of the wide-band oscillation suppression current; use the difference between the grid-connected current and the output current of the wide-band oscillation suppression device as the input signal of the current suppression loop, and the current suppression loop outputs the second reference value of the wide-band oscillation suppression current; use the sum of the first reference value and the second reference value of the wide-band oscillation suppression current as the wide-band oscillation suppression current instruction; the wide-band oscillation suppression device adjusts the output current according to the wide-band oscillation suppression current instruction.

[0040] The broadband oscillation controller has a built-in shutdown control module; the shutdown control module is used to control the broadband oscillation suppression device to take the moment of receiving the broadband oscillation suppression current instruction as the starting moment, and from the starting moment, the broadband oscillation current is sampled within W consecutive oscillation cycles. If the broadband oscillation current amplitude sampled within the wth oscillation cycle is satisfy: w∈[1,W], ζ is the divergence coefficient, then it is determined that the broadband oscillation current continues to diverge, and the broadband oscillation suppression device stops operating. Preferably, the divergence coefficient ζ is 1.05.

[0041] The voltage suppression loop and the current suppression loop have the same topological structure, both including an industrial frequency filtering link, an oscillation frequency filtering link, a phase shifting link and a proportional link; the industrial frequency filtering link adopts a second-order band-stop filter, the oscillation frequency filtering link adopts a second-order band-pass filter, and the phase shifting link adopts two series-connected phase shifters.

[0042] The beneficial effects of the present invention are that, compared with the prior art, at least the adaptive suppression strategy proposed by the present invention can realize online adaptive adjustment of the control parameters of the wide-band oscillation suppression controller, adapt to changes in system working conditions, and can still effectively suppress oscillation after the oscillation frequency shifts. The oscillation suppression strategy proposed by the present invention is highly robust and easy to implement in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic diagram of a wind farm electrical system to which a broadband oscillation suppression strategy is applied as proposed by the present invention;

[0044] Figure 2 It is a structural block diagram of the wide-frequency oscillation controller proposed by the present invention;

[0045] Figure 3 is a flow chart of a broadband oscillation suppression strategy according to an embodiment of the present invention;

[0046] Figure 4 is a simulation waveform diagram of a conventional suppression strategy in an embodiment of the present invention;

[0047] Figure 5 It is a simulation waveform diagram of the suppression strategy proposed by the present invention in the embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0049] The wind farm electrical system that applies the broadband oscillation suppression strategy is as follows: Figure 1 As shown, a 100MW wind farm includes n double-fed wind turbines DFIG, and a broadband oscillation suppression device is connected to the grid-connected busbar; the present invention proposes a broadband oscillation suppression method based on impedance update of a new energy station, including:

[0050] Step 1: Obtain the grid-connected voltage oscillation vector and the grid-connected current oscillation vector at the oscillation frequency point, and the output current oscillation vector of the broadband oscillation suppression device at the oscillation frequency point to calculate the impedance vector of the new energy station at the oscillation frequency point.

[0051] In the embodiment, the grid-connected bus is a 35kV bus, and the three-phase voltage v of the 35kV grid-connected point is collected. 35kV,abc , 35kV grid-connected three-phase current i 35kV,abc And the wide-band oscillation suppression device output current i SDC,abc, using the collected data, the FFT method is used to calculate the grid-connected voltage oscillation vector and the grid-connected current oscillation vector at the oscillation frequency point, and the output current oscillation vector of the wide-band oscillation suppression device at the oscillation frequency point is calculated.

[0052] The impedance vector of the new energy station at the oscillation frequency point is calculated using the following relationship:

[0053]

[0054] In the formula, is the impedance vector of the new energy station at the oscillation frequency point, is the grid-connected voltage oscillation vector at the oscillation frequency point, is the grid-connected current oscillation vector at the oscillation frequency point, is the output current oscillation vector of the broadband oscillation suppression device at the oscillation frequency point, is the real part of the impedance vector of the new energy station at the oscillation frequency point, It is the imaginary part of the impedance vector of the new energy field station at the oscillation frequency point.

[0055] The impedance vector Z of the new energy station at the oscillation frequency point renew is the actual impedance vector calculated using actual measured data.

[0056] Step 2: When the grid-connected voltage oscillation amplitude at the oscillation frequency point is greater than the set voltage oscillation threshold and / or the grid-connected current oscillation amplitude at the oscillation frequency point is greater than the set current oscillation threshold, the impedance vector of the new energy station at the oscillation frequency point is updated using the set impedance angle, and the impedance vector of the new energy station at the oscillation frequency point before the update and the impedance vector of the new energy station at the oscillation frequency point after the update are used to calculate the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point.

[0057] In the embodiment, the voltage oscillation threshold V is set TH The value range is [0.01~0.1], and the set current oscillation threshold I TH The value range is [0.05~0.2].

[0058] Specifically, step 2 includes:

[0059] Step 2.1, update the impedance vector of the new energy station at the oscillation frequency point using the following relationship:

[0060]

[0061] In the formula, is the impedance vector of the updated new energy station at the oscillation frequency point, θ eq is the set impedance angle, θ eqThe value range is [0, 90°]. In the embodiment, θ eq The value is 70°.

[0062] Introduce the set impedance angle and transform the impedance vector of the new energy field at the oscillation frequency point The vector angle is corrected to between 0-90°, and the updated impedance vector of the new energy field station at the oscillation frequency point is obtained.

[0063] Step 2.2, calculate the admittance vector of the broadband oscillation suppression device at the oscillation frequency point using the following relationship:

[0064]

[0065] In the formula, is the admittance vector of the broadband oscillation suppression device at the updated oscillation frequency point, is the admittance vector of the updated new energy station at the oscillation frequency point, is the admittance vector of the new energy station at the oscillation frequency point,

[0066] Admittance vector of the broadband oscillation suppression device at the updated oscillation frequency point in, is the modulus of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, θ SDC is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point; the admittance vector of the new energy field station at the oscillation frequency point before the update in, is the modulus of the admittance vector of the new energy station at the oscillation frequency point before updating, θ renew is the vector angle of the admittance vector of the new energy field station at the oscillation frequency point before updating.

[0067] The admittance vector of the broadband oscillation suppression device at the oscillation frequency point, determined by the difference between the impedance vector of the new energy field station at the oscillation frequency point before the update and the impedance vector of the new energy field station at the oscillation frequency point after the update, is the oscillation supplementary vector that the broadband oscillation suppression device needs to output.

[0068] Step 3, using the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point, update the control parameters of the voltage suppression loop and then start the voltage suppression loop; at the same time, using the admittance vector of the new energy field at the oscillation frequency point before the update and the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point, update the control parameters of the current suppression loop and then start the current suppression loop.

[0069] Specifically, the control parameters of the voltage suppression loop include: voltage phase shift angle, voltage proportional coefficient and voltage phase shift time constant;

[0070] The voltage phase shift angle and voltage proportional coefficient are determined by the following relationship:

[0071]

[0072] In the formula, θ PS_V is the voltage phase shift angle of the voltage suppression loop, θ SDC is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, K V is the voltage proportionality coefficient of the voltage suppression loop, is the modulus of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point;

[0073] The voltage phase shift time constant is determined by the following relationship:

[0074]

[0075] Where, T V is the voltage phase shift time constant, ω sso is the angular frequency at the oscillation frequency point;

[0076] Specifically, the control parameters of the current suppression loop include: current phase shift angle, current proportionality coefficient and current phase shift time constant;

[0077] The current phase shift angle and current proportionality coefficient are determined by the following relationship:

[0078]

[0079] In the formula, θ PS_I is the current phase shift angle of the current suppression loop, θ renew is the vector angle of the admittance vector of the new energy station at the oscillation frequency point, θ SDC is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, K I is the current proportionality coefficient of the current suppression loop, is the modulus of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, is the modulus of the admittance vector of the new energy station at the oscillation frequency point;

[0080] The current phase shift time constant is determined by the following relationship:

[0081]

[0082] Where, T I is the current phase shift time constant, ω sso is the angular frequency at the oscillation frequency point.

[0083] Step 4, using the grid voltage as the input signal of the voltage suppression loop, the voltage suppression loop outputs the first reference value of the wide-band oscillation suppression current; using the difference between the grid current and the output current of the wide-band oscillation suppression device as the input signal of the current suppression loop, the current suppression loop outputs the second reference value of the wide-band oscillation suppression current; using the sum of the first reference value and the second reference value of the wide-band oscillation suppression current as the wide-band oscillation suppression current instruction; the wide-band oscillation suppression device adjusts the output current according to the wide-band oscillation suppression current instruction.

[0084] Step 5: The broadband oscillation suppression device takes the moment when the broadband oscillation suppression current instruction is received as the starting moment, and samples the broadband oscillation current within W consecutive oscillation cycles from the starting moment. If the broadband oscillation current amplitude sampled within the wth oscillation cycle is satisfy: w∈[1,W], ζ is the divergence coefficient, then it is determined that the broadband oscillation current continues to diverge, and the broadband oscillation suppression device stops operating.

[0085] In the embodiment, the divergence coefficient ζ is set to 1.05.

[0086] The wind farm electrical system that applies the broadband oscillation suppression strategy is as follows: Figure 2 As shown in the figure, the 100MW wind farm includes n double-fed wind turbines DFIG, with a rated power of 1.5MVA, a stator rated voltage of 690V, and a rotor rated voltage of 900V. Each DFIG is connected to a 0.69kV busbar through a machine-side converter RSC and a grid-side converter GSC. The 0.69kV busbar is connected to a 0.69 / 35kV transformer T 1i and 0.69kV transmission line equivalent resistance Z 1i The 35kV bus is connected to the broadband oscillation suppression device proposed by the present invention, and the broadband oscillation suppression device inputs a current i to the 35kV bus. SDC,abc , 35kV busbar through 35 / 220kV transformer T 21 The 220kV busbar is connected to the 35kV transmission line with an equivalent resistance of 24.25Ω and an equivalent inductance of 0.77H. The 220kV busbar is connected to the 220kV transmission line through an equivalent impedance Z2 (equivalent resistance of 0.96Ω and equivalent inductance of 0.4775H) and a 220 / 500kV transformer T 31 Connect to 500kV busbar, equivalent resistance R of 500kV transmission line L , equivalent inductive reactance X L , equivalent capacitive reactance X C (equivalent resistance is 15Ω, equivalent inductance is 0.4775H, equivalent capacitance is 53uF); where i=1,2,…,n, n=66.

[0087] The present invention also proposes a broadband oscillation suppression system based on impedance update of a new energy station, comprising:

[0088] An adaptive adjustment module is used to obtain a grid-connected voltage oscillation vector and a grid-connected current oscillation vector at an oscillation frequency point, and an output current oscillation vector of a wide-band oscillation suppression device at an oscillation frequency point, so as to calculate an impedance vector of a new energy station at the oscillation frequency point; when the grid-connected voltage oscillation amplitude at the oscillation frequency point is greater than a set voltage oscillation threshold value and / or the grid-connected current oscillation amplitude at the oscillation frequency point is greater than a set current oscillation threshold value, the impedance vector of the new energy station at the oscillation frequency point is updated using a set impedance angle, and the impedance vector of the new energy station at the oscillation frequency point before the update and the impedance vector of the new energy station at the oscillation frequency point after the update are used to calculate the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point; the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point is used to update the control parameters of the voltage suppression loop and then start the voltage suppression loop; at the same time, the admittance vector of the new energy station at the oscillation frequency point before the update and the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point are used to update the control parameters of the current suppression loop and then start the current suppression loop;

[0089] A wide-band oscillation controller is used to use the grid-connected voltage as the input signal of the voltage suppression loop, and the voltage suppression loop outputs the first reference value of the wide-band oscillation suppression current; use the difference between the grid-connected current and the output current of the wide-band oscillation suppression device as the input signal of the current suppression loop, and the current suppression loop outputs the second reference value of the wide-band oscillation suppression current; use the sum of the first reference value and the second reference value of the wide-band oscillation suppression current as the wide-band oscillation suppression current instruction; the wide-band oscillation suppression device adjusts the output current according to the wide-band oscillation suppression current instruction.

[0090] The broadband oscillation controller has a built-in shutdown control module; the shutdown control module is used to control the broadband oscillation suppression device to take the moment of receiving the broadband oscillation suppression current instruction as the starting moment, and from the starting moment, the broadband oscillation current is sampled within W consecutive oscillation cycles. If the broadband oscillation current amplitude sampled within the wth oscillation cycle is satisfy: w∈[1,W], ζ is the divergence coefficient, then it is determined that the broadband oscillation current continues to diverge, and the broadband oscillation suppression device stops operating.

[0091] The voltage suppression loop and the current suppression loop have the same topology, such as Figure 2 As shown, they all include power frequency filtering link, oscillation frequency filtering link, phase shifting link and ratio link. In the embodiment, the power frequency filtering link adopts a second-order band-stop filter, the oscillation frequency filtering link adopts a second-order band-pass filter, and the phase shifting link adopts two phase shifters connected in series.

[0092] In the embodiment, the transfer function of the power frequency filtering link is: Among them, ω1 is the power frequency angular frequency, s is the Laplace operator, k s is the gain coefficient of the second-order band-stop filter, which has the same value in the voltage suppression loop and the current suppression loop; the transfer function of the oscillation frequency filter link is Among them, ω sso is the angular frequency at the oscillation frequency point, k p is the gain coefficient of the second-order bandpass filter, which has the same value in the voltage suppression loop and the current suppression loop; the transfer function of the phase shift link of the voltage suppression loop is The transfer function of the phase shift link of the current suppression loop is The proportional link of the voltage suppression loop corresponds to the voltage proportional coefficient K V , the proportional link of the current suppression loop corresponds to the current proportional coefficient K I ; Wide frequency oscillation controller with 35kV grid point voltage v 35kV,abc 、35kV grid-connected current i 35kV,abc The output current i SDC,abc The difference is the input signal, and the wide-band oscillation suppression current instruction is obtained. By adaptively adjusting the voltage phase shift time constant and the current phase shift time constant, the voltage proportional coefficient and the current proportional coefficient, the output current of the wide-band oscillation suppression device is updated to suppress the wide-band oscillation current in the system.

[0093] The workflow of the broadband oscillation suppression system based on impedance update of new energy stations proposed in the present invention is as follows: Figure 3 As shown, including:

[0094] 1) Measure the 35kV grid connection point voltage v of the wind farm system 35kV,abc , 35kV grid-connected current i 35kV,abc And the output current i of the broadband oscillation suppression device SDC,abc ;

[0095] 2) Determine the suppression function input flag En SDC and suppress the function failure flag Fail SDC Whether it is set, if not set, continue to execute the oscillation suppression process, otherwise exit the oscillation suppression process;

[0096] 3) Based on the measured voltage and current oscillation vector, calculate the impedance vector of the new energy station at the oscillation frequency point Let the impedance angle θ be set eq Take the value as 70° and calculate the impedance vector of the new energy station at the updated oscillation frequency point

[0097] 4) Determine whether the grid-connected voltage oscillation amplitude at the oscillation frequency point is greater than the set voltage oscillation threshold V TH If it is greater than, the suppression function will be put into the flag En SDC Set to 1, calculate the control parameters of the voltage suppression loop and start the voltage suppression loop; determine whether the grid-connected current oscillation amplitude at the oscillation frequency point is greater than the set current oscillation threshold I TH If it is greater than, the suppression function will be put into the flag En SDC Set to 1, and start the current suppression loop after calculating the control parameters of the current suppression loop; among them, the set voltage oscillation threshold V TH The value range is [0.01~0.1], and the set current oscillation threshold I TH The value range is [0.05~0.2];

[0098] 5) The wide-band oscillation controller performs work and outputs a wide-band oscillation suppression current instruction to the wide-band oscillation suppression device;

[0099] 6) If the suppression function is enabled, the flag En is SDC If set to 1, the oscillation suppression effect judgment logic will be executed after 1 second, and the divergence coefficient ζ is set to 1.05. When the amplitude of the broadband oscillation current obtained by this sampling exceeds ζ times the amplitude of the broadband oscillation current obtained by the previous sampling within 3 consecutive oscillation cycles, the suppression function failure flag Failure will be set. SDC Set to 1 to exit the oscillation suppression process.

[0100] In order to highlight the implementation effect of the present invention, a comparison is made with the conventional suppression strategy using constant parameters, such as Figure 4 and Figure 5 shown. Figure 4 and Figure 5 In the figure, the horizontal axis of the waveform is time Tine (sec), and the vertical axis of the waveform is 35kV a phase voltage V from top to bottom. a 、35kV a-phase current I a , Wide-band oscillation suppression device a phase output current command I asdcref , Wide-band oscillation suppression device a phase output current measurement value I asdcmeas 、Oscillation frequency Freq sso , wide frequency oscillating current I sso .

[0101] When the simulation time t=8 seconds, the wind speed dropped from 11m / s to 5m / s, the broadband oscillation suppression strategy was not put into use, and the system experienced low-frequency oscillations of about 10Hz. After the broadband oscillation suppression function was put into use, both the conventional suppression strategy and the suppression strategy proposed in the present invention can effectively suppress 10Hz oscillations. When the simulation time t=10 seconds, the series compensation of the line was increased, and the system oscillation frequency shifted from 10Hz to 13Hz. After that, the conventional suppression strategy failed, the system oscillation continued to diverge, and the suppression strategy described in the present invention was still effective. It can be seen that the broadband oscillation suppression strategy of the present invention is more robust.

[0102] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0103] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0104] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0105] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A broadband oscillation suppression method based on impedance update of new energy stations, characterized in that: include: Obtaining the grid-connected voltage oscillation vector and the grid-connected current oscillation vector at the oscillation frequency point, and the output current oscillation vector of the wide-band oscillation suppression device at the oscillation frequency point, so as to calculate the impedance vector of the new energy station at the oscillation frequency point; When the grid-connected voltage oscillation amplitude at the oscillation frequency point is greater than the set voltage oscillation threshold value and / or the grid-connected current oscillation amplitude at the oscillation frequency point is greater than the set current oscillation threshold value, the impedance vector of the new energy station at the oscillation frequency point is updated using the set impedance angle, and the impedance vector of the new energy station at the oscillation frequency point before the update and the impedance vector of the new energy station at the oscillation frequency point after the update are used to calculate the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point; Using the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point, the control parameters of the voltage suppression loop are updated and then the voltage suppression loop is started; at the same time, using the admittance vector of the new energy field station at the oscillation frequency point before the update and the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point, the control parameters of the current suppression loop are updated and then the current suppression loop is started; The grid-connected voltage is used as an input signal of a voltage suppression loop, and the voltage suppression loop outputs a first reference value of a wide-band oscillation suppression current; The difference between the grid-connected current and the output current of the wide-band oscillation suppression device is used as an input signal of the current suppression loop, and the current suppression loop outputs a second reference value of the wide-band oscillation suppression current; Using the sum of the first reference value and the second reference value of the wide-frequency oscillation suppression current as the wide-frequency oscillation suppression current instruction; The wide-band oscillation suppression device adjusts the output current according to the wide-band oscillation suppression current instruction.

2. The broadband oscillation suppression method based on impedance update of new energy stations according to claim 1 is characterized in that: The impedance vector of the new energy station at the oscillation frequency point is calculated using the following relationship: In the formula, is the impedance vector of the new energy station at the oscillation frequency point, is the grid-connected voltage oscillation vector at the oscillation frequency point, is the grid-connected current oscillation vector at the oscillation frequency point, is the output current oscillation vector of the broadband oscillation suppression device at the oscillation frequency point, is the real part of the impedance vector of the new energy station at the oscillation frequency point, It is the imaginary part of the impedance vector of the new energy field station at the oscillation frequency point.

3. The broadband oscillation suppression method based on impedance update of new energy stations according to claim 1 is characterized in that: Set the voltage oscillation threshold V TH The value range is [0.01~0.1], and the set current oscillation threshold I TH The value range is [0.05~0.2].

4. The broadband oscillation suppression method based on impedance update of new energy stations according to claim 2 is characterized in that: Update the impedance vector of the new energy station at the oscillation frequency point using the following relationship: In the formula, is the impedance vector of the updated new energy station at the oscillation frequency point, θ eq is the set impedance angle, θ eq The value range is [0, 90°]; The admittance vector of the broadband oscillation suppression device at the oscillation frequency point is calculated using the following relationship: In the formula, is the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, is the admittance vector of the updated new energy station at the oscillation frequency point, is the admittance vector of the new energy station at the oscillation frequency point, 5. The broadband oscillation suppression method based on impedance update of new energy stations according to claim 1 is characterized in that: The control parameters of the voltage suppression loop include: voltage phase shift angle, voltage proportional coefficient and voltage phase shift time constant; The voltage phase shift angle and voltage proportional coefficient are determined by the following relationship: In the formula, θ PS_V is the voltage phase shift angle of the voltage suppression loop, θ SDC is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, K V is the voltage proportionality coefficient of the voltage suppression loop, is the modulus of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point; The voltage phase shift time constant is determined by the following relationship: Where, T V is the voltage phase shift time constant, ω sso is the angular frequency at the oscillation frequency point.

6. The broadband oscillation suppression method based on impedance update of new energy stations according to claim 1 is characterized in that: The control parameters of the current suppression loop include: current phase shift angle, current proportionality coefficient and current phase shift time constant; The current phase shift angle and current proportionality coefficient are determined by the following relationship: In the formula, θ PS_I is the current phase shift angle of the current suppression loop, θ renew is the vector angle of the admittance vector of the new energy station at the oscillation frequency point, θ SDC is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, K I is the current proportionality coefficient of the current suppression loop, is the modulus of the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, is the modulus of the admittance vector of the new energy station at the oscillation frequency point; The current phase shift time constant is determined by the following relationship: Where, T I is the current phase shift time constant, ω sso is the angular frequency at the oscillation frequency point.

7. The broadband oscillation suppression method based on impedance update of new energy stations according to claim 1 is characterized in that: Also includes: The broadband oscillation suppression device takes the moment of receiving the broadband oscillation suppression current instruction as the starting moment, and samples the broadband oscillation current within W consecutive oscillation cycles from the starting moment. If the broadband oscillation current amplitude sampled within the wth oscillation cycle is satisfy: w∈[1,W], ζ is the divergence coefficient, then it is determined that the broadband oscillation current continues to diverge, and the broadband oscillation suppression device stops operating.

8. A broadband oscillation suppression system based on impedance update of new energy stations, characterized in that: include: An adaptive adjustment module is used to obtain a grid-connected voltage oscillation vector and a grid-connected current oscillation vector at an oscillation frequency point, and an output current oscillation vector of a wide-band oscillation suppression device at an oscillation frequency point, so as to calculate an impedance vector of a new energy station at the oscillation frequency point; when the grid-connected voltage oscillation amplitude at the oscillation frequency point is greater than a set voltage oscillation threshold value and / or the grid-connected current oscillation amplitude at the oscillation frequency point is greater than a set current oscillation threshold value, the impedance vector of the new energy station at the oscillation frequency point is updated using a set impedance angle, and the impedance vector of the new energy station at the oscillation frequency point before the update and the impedance vector of the new energy station at the oscillation frequency point after the update are used to calculate the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point; the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point is used to update the control parameters of the voltage suppression loop and then start the voltage suppression loop; at the same time, the admittance vector of the new energy station at the oscillation frequency point before the update and the admittance vector of the wide-band oscillation suppression device at the oscillation frequency point are used to update the control parameters of the current suppression loop and then start the current suppression loop; A wide-band oscillation controller, used to use the grid-connected voltage as an input signal of a voltage suppression loop, and the voltage suppression loop outputs a first reference value of a wide-band oscillation suppression current; The difference between the grid-connected current and the output current of the wide-band oscillation suppression device is used as an input signal of the current suppression loop, and the current suppression loop outputs a second reference value of the wide-band oscillation suppression current; Using the sum of the first reference value and the second reference value of the wide-frequency oscillation suppression current as the wide-frequency oscillation suppression current instruction; The wide-band oscillation suppression device adjusts the output current according to the wide-band oscillation suppression current instruction.

9. The broadband oscillation suppression system based on impedance update of new energy stations according to claim 8 is characterized in that: The broadband oscillation controller has a built-in shutdown control module; the shutdown control module is used to control the broadband oscillation suppression device to take the moment of receiving the broadband oscillation suppression current instruction as the starting moment, and from the starting moment, the broadband oscillation current is sampled within W consecutive oscillation cycles. If the broadband oscillation current amplitude sampled within the wth oscillation cycle is satisfy: w∈[1,W], ζ is the divergence coefficient, then it is determined that the broadband oscillation current continues to diverge, and the broadband oscillation suppression device stops operating.

10. The broadband oscillation suppression system based on impedance update of new energy stations according to claim 8, characterized in that: The voltage suppression loop and the current suppression loop have the same topological structure, both including an industrial frequency filtering link, an oscillation frequency filtering link, a phase shifting link and a proportional link; the industrial frequency filtering link adopts a second-order band-stop filter, the oscillation frequency filtering link adopts a second-order band-pass filter, and the phase shifting link adopts two series-connected phase shifters.

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