A Broadband Oscillation Suppression Method and System Based on Impedance Update of New Energy Power Stations

Abstract

A broadband oscillation suppression method and system based on impedance updating of new energy power plants addresses the following issues: When the grid-connected voltage oscillation amplitude at the oscillation frequency point exceeds the voltage oscillation threshold and / or the grid-connected current oscillation amplitude at the oscillation frequency point exceeds the current oscillation threshold, the impedance vector of the new energy power plant at the oscillation frequency point is updated using a set impedance angle, and the admittance vector of the broadband oscillation suppression device at the oscillation frequency point is calculated to update the control parameters of the voltage and current suppression loops. The grid-connected voltage is used as the input signal for the voltage suppression loop, which outputs a first reference value for the broadband oscillation suppression current. The difference between the grid-connected current and the output current of the broadband oscillation suppression device is used as the input signal for the current suppression loop, which outputs a second reference value for the broadband oscillation suppression current. The sum of the first and second reference values ​​of the broadband oscillation suppression current is used as the broadband oscillation suppression current command, thus avoiding the problem of inaccurate extraction of a single voltage oscillation quantity.

Description

Technical Field

[0001] This invention belongs to the fields of power electronics technology and broadband oscillation suppression, specifically relating to a broadband oscillation adaptive suppression method and system based on new energy impedance updates. Background Technology

[0002] With the development of new power systems, large-scale power electronic equipment is continuously being connected to the grid, making power system stability issues more complex. In particular, small-disturbance stability requires attention to a wider frequency range, not just the vicinity of the synchronization frequency. In recent years, broadband oscillation events have occurred repeatedly, causing a large number of new energy units to trip and be disconnected, affecting the safe and stable operation of the power grid.

[0003] Existing literature indicates that broadband oscillations are closely related to the impedance characteristics of renewable energy generating units. Adjusting the control parameters of these units can effectively suppress oscillations. However, due to the large scale of renewable energy generating units, adjusting control parameters is time-consuming and labor-intensive. In practice, it is desirable to solve the oscillation problem by connecting an additional damping suppression device based on a power electronic converter in parallel, without altering the original controller and its parameters.

[0004] In existing broadband oscillation suppression solutions based on impedance updates, only voltage information is typically extracted as input to the suppression strategy. A drawback of this approach is that it is difficult to accurately extract effective information when the voltage oscillation is small. Furthermore, conventional suppression strategies generally only work for a specific frequency band and cannot be adjusted online according to the oscillation frequency, resulting in poor applicability. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a broadband oscillation suppression method and system based on impedance updates of new energy power plants. This method can use both voltage and current as inputs to the suppression strategy, thus avoiding the problem of inaccurate extraction of a single voltage oscillation.

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

[0007] This invention proposes a broadband oscillation suppression method based on impedance updates of renewable energy power plants, comprising:

[0008] Obtain the grid-connected voltage oscillation vector and 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, in order to calculate the impedance vector of the new energy power 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 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 power station at the oscillation frequency point is updated using the set impedance angle, and the admittance vector of the broadband oscillation suppression device at the oscillation frequency point is calculated using the impedance vector of the new energy power station at the oscillation frequency point before the update and the impedance vector of the new energy power station at the oscillation frequency point after the update.

[0010] The voltage suppression loop is started after updating the control parameters of the voltage suppression loop by using the admittance vector of the broadband oscillation suppression device at the oscillation frequency point; at the same time, the current suppression loop is started after updating the control parameters of the current suppression loop by using the admittance vector of the new energy power station at the oscillation frequency point before the update and the admittance vector of the broadband oscillation suppression device at the oscillation frequency point.

[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 for the wideband oscillation suppression current. The difference between the grid-connected current and the output current of the wideband oscillation suppression device is used as the input signal of the current suppression loop, and the current suppression loop outputs a second reference value for the wideband oscillation suppression current. The sum of the first and second reference values ​​of the wideband oscillation suppression current is used as the wideband oscillation suppression current command. The wideband oscillation suppression device adjusts its output current according to the wideband oscillation suppression current command.

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

[0013]

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

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

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

[0017]

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

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

[0020]

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

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

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

[0024]

[0025] In the formula, θ PS_V θ is the voltage phase shift angle of the voltage suppression loop. SDC K is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. V This is the voltage proportionality coefficient of the voltage suppression loop. Let be the magnitude of the admittance vector of the broadband oscillation suppression device at the oscillation frequency.

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

[0027]

[0028] In the formula, T V Let ω be the voltage phase shift time constant. sso ω 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 proportional 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 θ is the current phase shift angle of the current suppression loop. renew Let θ be the vector angle of the admittance vector of the new energy power station at the oscillation frequency point. SDC K is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. I This is the current proportionality coefficient for the current suppression loop. Let be the magnitude of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. Let be the magnitude of the admittance vector of the new energy power station at the oscillation frequency point;

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

[0034]

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

[0036] Preferably, the method further includes: the broadband oscillation suppression device takes the moment of receiving the broadband oscillation suppression current command as the starting moment, and samples the broadband oscillation current within W consecutive oscillation cycles starting from the starting moment; if the amplitude of the broadband oscillation current sampled in the w-th oscillation cycle is... satisfy: If w∈[1,W] and ζ is the divergence coefficient, then the broadband oscillation current is determined to be continuously diverging, and the broadband oscillation suppression device is shut down.

[0037] This invention also proposes a broadband oscillation suppression system based on impedance updates of renewable energy power plants, comprising:

[0038] The adaptive adjustment module is used to obtain the grid-connected voltage oscillation vector and grid-connected current oscillation vector at the oscillation frequency point, as well as 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 power 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 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 power station at the oscillation frequency point is updated using the set impedance angle, and the impedance vector of the new energy power station at the oscillation frequency point before and after the update is used to calculate the admittance vector of the broadband oscillation suppression device at the oscillation frequency point. The voltage suppression loop is started after updating the control parameters of the voltage suppression loop using the admittance vector of the broadband oscillation suppression device at the oscillation frequency point. At the same time, the current suppression loop is started after updating the control parameters of the current suppression loop using the admittance vector of the new energy power station at the oscillation frequency point before and after the update is used to the broadband oscillation suppression device.

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

[0040] The wideband oscillation controller has a built-in shutdown control module. This module controls the wideband oscillation suppression device to sample the wideband oscillation current over W consecutive oscillation cycles, starting from the moment the wideband oscillation suppression current command is received. If the amplitude of the wideband oscillation current sampled in the w-th oscillation cycle is... satisfy: If w∈[1,W] and ζ is the divergence coefficient, then the broadband oscillation current is determined to be continuously diverging, and the broadband oscillation suppression device is shut down. Preferably, the divergence coefficient ζ is 1.05.

[0041] The voltage suppression loop and the current suppression loop have the same topology, both including a power frequency filter, an oscillation frequency filter, a phase shifter, and a proportional element. The power frequency filter uses a second-order band-stop filter, the oscillation frequency filter uses a second-order band-pass filter, and the phase shifter uses two phase shifters connected in series.

[0042] The beneficial effects of this invention are, at least compared with the prior art, that the adaptive suppression strategy proposed in this invention can achieve online adaptive adjustment of the control parameters of the wideband oscillation suppression controller, adapting to changes in system operating conditions, and effectively suppressing oscillations even after the oscillation frequency has shifted. The oscillation suppression strategy proposed in this invention is robust and easy to implement in engineering. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a wind farm electrical system employing a broadband oscillation suppression strategy proposed in this invention;

[0044] Figure 2 This is a structural block diagram of the wideband oscillation controller proposed in this invention;

[0045] Figure 3 This is a flowchart of the wideband oscillation suppression strategy in an embodiment of the present invention;

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

[0047] Figure 5 This is a simulation waveform diagram of the suppression strategy proposed in this invention in an embodiment of the invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0049] Wind farm electrical systems with broadband oscillation suppression strategies, such as Figure 1 As shown, a 100MW wind farm includes n doubly-fed induction generator (DFIG) wind turbine units, with a broadband oscillation suppression device connected to the grid bus. This invention proposes a broadband oscillation suppression method based on impedance updating of new energy power plants, including:

[0050] Step 1: Obtain the grid-connected voltage oscillation vector and 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, in order to calculate the impedance vector of the new energy power station at the oscillation frequency point.

[0051] In this embodiment, the grid-connected bus is a 35kV bus, and the three-phase voltage v at the 35kV grid connection point is collected. 35kV,abc 35kV grid-connected three-phase current i 35kV,abc and the output current i of the wideband oscillation suppression device SDC,abcUsing the collected data, the grid voltage oscillation vector and grid current oscillation vector at the oscillation frequency point are calculated using the FFT method, and the output current oscillation vector of the broadband oscillation suppression device at the oscillation frequency point is also calculated.

[0052] The impedance vector of the renewable energy power station at the oscillation frequency point is calculated using the following formula:

[0053]

[0054] In the formula, Let be the impedance vector of the new energy power station at the oscillation frequency point. This represents the grid-connected voltage oscillation vector at the oscillation frequency point. Let be the oscillation vector of the grid-connected current at the oscillation frequency point. This represents the output current oscillation vector of the broadband oscillation suppression device at the oscillation frequency point. Let be the real part of the impedance vector of the renewable energy power station at the oscillation frequency. This is the imaginary part of the impedance vector of the new energy power station at the oscillation frequency point.

[0055] The impedance vector Z of the new energy power station at the oscillation frequency point renew It is the actual impedance vector calculated using actual measurement 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 power station at the oscillation frequency point is updated using the set impedance angle, and the admittance vector of the broadband oscillation suppression device at the oscillation frequency point is calculated using the impedance vector of the new energy power station before the update and the impedance vector of the new energy power station at the oscillation frequency point after the update.

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

[0058] Specifically, step 2 includes:

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

[0060]

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

[0062] Introducing a set impedance angle, the impedance vector of the new energy power station at the oscillation frequency point is... The vector angle is corrected to between 0 and 90° to obtain the updated impedance vector of the new energy power station at the oscillation frequency point.

[0063] Step 2.2: Calculate the admittance vector of the broadband oscillation suppression device at the oscillation frequency using the following formula:

[0064]

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

[0066] The admittance vector of the broadband oscillation suppression device at the updated oscillation frequency. in, Let θ be the magnitude of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. SDC 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 power station at the oscillation frequency point before the update. in, Let θ be the magnitude of the admittance vector of the new energy power station at the oscillation frequency point before the update. renew The vector angle is the admittance vector of the new energy power station at the oscillation frequency point before the update.

[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 power station before and after the update at the oscillation frequency point, is the oscillation supplement vector that the broadband oscillation suppression device needs to output.

[0068] Step 3: Using the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, update the control parameters of the voltage suppression loop and start the voltage suppression loop; at the same time, using the admittance vector of the new energy power station at the oscillation frequency point before the update and the admittance vector of the broadband oscillation suppression device at the oscillation frequency point, update the control parameters of the current suppression loop and start the current suppression loop.

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

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

[0071]

[0072] In the formula, θ PS_V θ is the voltage phase shift angle of the voltage suppression loop. SDC K is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. V This is the voltage proportionality coefficient of the voltage suppression loop. Let be the magnitude of the admittance vector of the broadband oscillation suppression device at the oscillation frequency.

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

[0074]

[0075] In the formula, T V Let ω be the voltage phase shift time constant. sso The angular frequency at the oscillation frequency point;

[0076] Specifically, the control parameters of the current suppression loop include: current phase shift angle, current proportional 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 θ is the current phase shift angle of the current suppression loop. renew Let θ be the vector angle of the admittance vector of the new energy power station at the oscillation frequency point. SDC K is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. I This is the current proportionality coefficient for the current suppression loop. Let be the magnitude of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. Let be the magnitude of the admittance vector of the new energy power station at the oscillation frequency point;

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

[0081]

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

[0083] Step 4: Using the grid-connected voltage as the input signal of the voltage suppression loop, the voltage suppression loop outputs a first reference value for the wideband oscillation suppression current; using the difference between the grid-connected current and the output current of the wideband oscillation suppression device as the input signal of the current suppression loop, the current suppression loop outputs a second reference value for the wideband oscillation suppression current; using the sum of the first and second reference values ​​of the wideband oscillation suppression current as the wideband oscillation suppression current command; the wideband oscillation suppression device adjusts its output current according to the wideband oscillation suppression current command.

[0084] Step 5: The broadband oscillation suppression device takes the moment of receiving the broadband oscillation suppression current command as the starting moment. From the starting moment, it samples the broadband oscillation current over W consecutive oscillation cycles. If the amplitude of the broadband oscillation current sampled in the w-th oscillation cycle is... satisfy: If w∈[1,W] and ζ is the divergence coefficient, then the broadband oscillation current is determined to be continuously diverging, and the broadband oscillation suppression device is shut down.

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

[0086] Wind farm electrical systems with broadband oscillation suppression strategies, such as Figure 2 As shown, the 100MW wind farm comprises n doubly-fed induction generator (DFIG) wind turbine units. Each DFIG has 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 bus via a turbine-side converter (RSC) and a grid-side converter (GSC). The 0.69kV bus is connected to a 0.69 / 35kV transformer (T). 1i and the equivalent resistance Z of the 0.69kV transmission line 1i Connect to a 35kV busbar, and connect the broadband oscillation suppression device proposed in this invention to the 35kV busbar. The broadband oscillation suppression device inputs a current i to the 35kV busbar. SDC,abc The 35kV busbar is connected to a 35 / 220kV transformer T. 21 The 220kV busbar is connected to the 35kV transmission line, which has an equivalent resistance of 24.25Ω and an equivalent inductance of 0.77H. The 220kV busbar is connected to the 220kV transmission line via an equivalent impedance Z2 (equivalent resistance of 0.96Ω and equivalent inductance of 0.4775H) and a 220 / 500kV transformer T. 31 The equivalent resistance R of a 500kV transmission line connected to a 500kV busbar. L Equivalent inductive reactance X L Equivalent capacitive reactance X C (Equivalent resistance is 15Ω, equivalent inductance is 0.4775H, and equivalent capacitance is 53uF); where i = 1, 2, ..., n, n = 66.

[0087] This invention also proposes a broadband oscillation suppression system based on impedance updates of renewable energy power plants, comprising:

[0088] The adaptive adjustment module is used to obtain the grid-connected voltage oscillation vector and grid-connected current oscillation vector at the oscillation frequency point, as well as 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 power 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 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 power station at the oscillation frequency point is updated using the set impedance angle, and the impedance vector of the new energy power station at the oscillation frequency point before and after the update is used to calculate the admittance vector of the broadband oscillation suppression device at the oscillation frequency point. The voltage suppression loop is started after updating the control parameters of the voltage suppression loop using the admittance vector of the broadband oscillation suppression device at the oscillation frequency point. At the same time, the current suppression loop is started after updating the control parameters of the current suppression loop using the admittance vector of the new energy power station at the oscillation frequency point before and after the update is used to the broadband oscillation suppression device.

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

[0090] The wideband oscillation controller has a built-in shutdown control module. This module controls the wideband oscillation suppression device to sample the wideband oscillation current over W consecutive oscillation cycles, starting from the moment the wideband oscillation suppression current command is received. If the amplitude of the wideband oscillation current sampled in the w-th oscillation cycle is... satisfy: If w∈[1,W] and ζ is the divergence coefficient, then the broadband oscillation current is determined to be continuously diverging, and the broadband oscillation suppression device is shut down.

[0091] Voltage suppression loops and current suppression loops have the same topology, such as Figure 2 As shown, each stage includes a power frequency filter, an oscillation frequency filter, a phase shifter, and a proportional stage. In this embodiment, the power frequency filter uses a second-order band-stop filter, the oscillation frequency filter uses a second-order bandpass filter, and the phase shifter uses two phase shifters connected in series.

[0092] In the embodiment, the transfer function of the power frequency filtering stage is: Where ω1 is the power frequency angular frequency, s is the Laplace operator, and k s The gain coefficient of the second-order band-stop filter is the same in both the voltage suppression loop and the current suppression loop; the transfer function of the oscillation frequency filtering stage is... Where, ω sso k is the angular frequency at the oscillation frequency point. p Let be the gain coefficient of the second-order bandpass filter, with the same value in both the voltage suppression loop and the current suppression loop; the transfer function of the phase-shifting element in the voltage suppression loop is... The transfer function of the phase-shifting element in the current suppression loop is: The proportional element of the voltage suppression loop corresponds to the voltage proportionality coefficient K. V The proportional element of the current suppression loop corresponds to the current proportional coefficient K. I The wideband oscillation controller operates at a 35kV grid connection point voltage. 35kV,abc 35kV grid-connected current i 35kV,abc With the output current i of the wideband oscillation suppression device SDC,abc The difference is taken as the input signal, and a wideband oscillation suppression current command is obtained. By adaptively adjusting the voltage phase shift time constant, current phase shift time constant, voltage proportional coefficient, and current proportional coefficient, the output current of the broadband oscillation suppression device is updated to suppress the broadband oscillation current in the system.

[0093] The workflow of the broadband oscillation suppression system based on impedance updating of new energy power plants proposed in this invention is as follows: Figure 3 As shown, it includes:

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

[0095] 2) Determine the indicator of inhibitory function activation En SDC and the failure flag for suppression function. SDC Whether to set the bit; if none are set, continue executing the oscillation suppression process; otherwise, exit the oscillation suppression process.

[0096] 3) Based on the measured voltage and current oscillation vectors, calculate the impedance vector of the new energy power station at the oscillation frequency point. Let the set impedance angle θ eq Taking a value of 70°, calculate the impedance vector of the new energy power 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 enabled by the flag En. SDC Set the bit to 1, calculate the control parameters of the voltage suppression loop, and then 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 enabled by the flag En. SDC The current suppression loop is started after the bit is set to 1 and the control parameters of the current suppression loop are calculated; where the set voltage oscillation threshold V TH The value range is [0.01~0.1], and the set current oscillation threshold I is... TH The value range is [0.05~0.2];

[0098] 5) The wideband oscillation controller performs its operation and outputs a wideband oscillation suppression current command to the wideband oscillation suppression device;

[0099] 6) If the inhibition function is activated by the flag En SDC If the bit is set to 1, the oscillation suppression effect judgment logic will be executed after 1 second. The divergence coefficient ζ is set to 1.05. If the amplitude of the broadband oscillation current obtained by the current sampling exceeds ζ times the amplitude of the broadband oscillation current obtained by the previous sampling in three consecutive oscillation cycles, the suppression function failure flag will be set to Fail. SDC Set the bit to 1 to exit the oscillation suppression process.

[0100] To highlight the effectiveness of this invention, a comparison was made with conventional suppression strategies using constant parameters, such as... Figure 4 and Figure 5 As shown. Figure 4 and Figure 5 In the diagram, the horizontal axis of the waveform represents time (Tine, sec), and the vertical axis of the waveform, from top to bottom, represents the 35kV a-phase voltage (V). a 35kV a-phase current I a Wideband oscillation suppression device a-phase output current command I asdcref Measurement value of phase a output current I of the wideband oscillation suppression device asdcmeas Oscillation frequency Freq sso Wideband oscillating current I sso .

[0101] At simulation time t = 8 seconds, the wind speed decreased from 11 m / s to 5 m / s. Without the broadband oscillation suppression strategy activated, the system exhibited low-frequency oscillations around 10 Hz. After activating the broadband oscillation suppression function, both the conventional suppression strategy and the suppression strategy proposed in this invention effectively suppressed the 10 Hz oscillation. At simulation time t = 10 seconds, the series compensation of the line was improved, and the system oscillation frequency shifted from 10 Hz to 13 Hz. Subsequently, the conventional suppression strategy failed, and the system oscillation continued to diverge, while the suppression strategy described in this invention remained effective. Therefore, the broadband oscillation suppression strategy of this invention has stronger robustness.

[0102] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0103] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

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

[0105] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status 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 the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving 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., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A broadband oscillation suppression method based on impedance updating of new energy power stations, characterized in that, include: The grid-connected voltage oscillation vector and grid-connected current oscillation vector at the oscillation frequency point, as well as the output current oscillation vector of the broadband oscillation suppression device at the oscillation frequency point, are obtained to calculate the impedance vector of the new energy power station at the oscillation frequency point, as follows: In the formula, Let be the impedance vector of the new energy power station at the oscillation frequency point. Let V be the grid-connected voltage oscillation vector at the oscillation frequency point. Let be the oscillation vector of the grid-connected current at the oscillation frequency point. This represents the output current oscillation vector of the broadband oscillation suppression device at the oscillation frequency point. Let be the real part of the impedance vector of the renewable energy power station at the oscillation frequency. This represents the imaginary part of the impedance vector of the new energy power station at the oscillation frequency point; When the grid-connected voltage oscillation amplitude at the oscillation frequency point exceeds the set voltage oscillation threshold and / or the grid-connected current oscillation amplitude at the oscillation frequency point exceeds the set current oscillation threshold, the impedance vector of the new energy power station at the oscillation frequency point is updated using the set impedance angle, as follows: In the formula, Let θ be the impedance vector of the updated renewable energy power station at the oscillation frequency point. eq θ is the set impedance angle. 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 impedance vector of the new energy power station before and after the update, as follows: In the formula, Let be the admittance vector of the broadband oscillation suppression device at the oscillation frequency. This is the updated admittance vector of the new energy power station at the oscillation frequency point. Let be the admittance vector of the new energy power station at the oscillation frequency point. The voltage suppression loop is started after updating the control parameters of the voltage suppression loop by using the admittance vector of the broadband oscillation suppression device at the oscillation frequency point; at the same time, the current suppression loop is started after updating the control parameters of the current suppression loop by using the admittance vector of the new energy power station at the oscillation frequency point before the update and the admittance vector of the broadband oscillation suppression device at the oscillation frequency point. The grid-connected voltage is used as the input signal of the voltage suppression loop, and the voltage suppression loop outputs the first reference value of the wideband oscillation suppression current. The difference between the grid-connected current and the output current of the broadband oscillation suppression device is used as the input signal of the current suppression loop, and the output of the current suppression loop is the second reference value of the broadband oscillation suppression current. The sum of the first and second reference values ​​of the wideband oscillation suppression current is used as the wideband oscillation suppression current command; The wideband oscillation suppression device adjusts the output current according to the wideband oscillation suppression current command.

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

3. The broadband oscillation suppression method based on impedance updating of new energy power stations according to claim 1, 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 proportionality coefficient are determined by the following relationship: In the formula, θ PS_V θ is the voltage phase shift angle of the voltage suppression loop. SDC K is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. V This is the voltage proportionality coefficient for the voltage suppression loop. Let be the magnitude of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. The voltage phase shift time constant is determined by the following relationship: In the formula, T V Let ω be the voltage phase shift time constant. sso ω is the angular frequency at the oscillation frequency point.

4. The broadband oscillation suppression method based on impedance updating of new energy power stations according to claim 1, characterized in that, The control parameters of the current suppression loop include: current phase shift angle, current proportional 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 θ is the current phase shift angle of the current suppression loop. renew Let θ be the vector angle of the admittance vector of the new energy power station at the oscillation frequency point. SDC K is the vector angle of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. I This is the current proportionality coefficient for the current suppression loop. Let be the magnitude of the admittance vector of the broadband oscillation suppression device at the oscillation frequency. Let be the magnitude of the admittance vector of the new energy power station at the oscillation frequency point; The current phase shift time constant is determined by the following relationship: In the formula, T I Let ω be the current phase shift time constant. sso ω is the angular frequency at the oscillation frequency point.

5. The broadband oscillation suppression method based on impedance updating of new energy power stations according to claim 1, characterized in that, Also includes: The broadband oscillation suppression device takes the moment of receiving the broadband oscillation suppression current command as the starting moment. From the starting moment, it samples the broadband oscillation current over W consecutive oscillation cycles. If the amplitude of the broadband oscillation current sampled in the w-th oscillation cycle is... satisfy: If ζ is the divergence coefficient, then it is determined that the broadband oscillation current continues to diverge, and the broadband oscillation suppression device will stop operating.

6. A broadband oscillation suppression system based on impedance updating of renewable energy power stations, used to implement the broadband oscillation suppression method based on impedance updating of renewable energy power stations as described in any one of claims 1 to 5, characterized in that, include: The adaptive adjustment module is used to obtain the grid-connected voltage oscillation vector and grid-connected current oscillation vector at the oscillation frequency point, as well as 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 power 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 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 power station at the oscillation frequency point is updated using the set impedance angle, and the impedance vector of the new energy power station at the oscillation frequency point before and after the update is used to calculate the admittance vector of the broadband oscillation suppression device at the oscillation frequency point. The voltage suppression loop is started after updating the control parameters of the voltage suppression loop using the admittance vector of the broadband oscillation suppression device at the oscillation frequency point. At the same time, the current suppression loop is started after updating the control parameters of the current suppression loop using the admittance vector of the new energy power station at the oscillation frequency point before and after the update is used to the broadband oscillation suppression device. A wideband oscillation controller is used to take 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 wideband oscillation suppression current; The difference between the grid-connected current and the output current of the broadband oscillation suppression device is used as the input signal of the current suppression loop, and the output of the current suppression loop is the second reference value of the broadband oscillation suppression current. The sum of the first and second reference values ​​of the wideband oscillation suppression current is used as the wideband oscillation suppression current command; The wideband oscillation suppression device adjusts the output current according to the wideband oscillation suppression current command.

7. The broadband oscillation suppression system based on impedance updating of new energy power stations according to claim 6, characterized in that, The wideband oscillation controller has a built-in shutdown control module. This module controls the wideband oscillation suppression device to sample the wideband oscillation current over W consecutive oscillation cycles, starting from the moment the wideband oscillation suppression current command is received. If the amplitude of the wideband oscillation current sampled in the w-th oscillation cycle is... satisfy: If w∈[1,W] and ζ is the divergence coefficient, then the broadband oscillation current is determined to be continuously diverging, and the broadband oscillation suppression device is shut down.

8. The broadband oscillation suppression system based on impedance updating of new energy power stations according to claim 6, characterized in that, The voltage suppression loop and the current suppression loop have the same topology, both including a power frequency filter, an oscillation frequency filter, a phase shifter, and a proportional element. The power frequency filter uses a second-order band-stop filter, the oscillation frequency filter uses a second-order band-pass filter, and the phase shifter uses two phase shifters connected in series.

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