Subsynchronous resonance suppression method and device, electronic equipment and storage medium

Abstract

The application provides a subsynchronous resonance suppression method and device, electronic equipment and storage medium, and belongs to the field of stable operation of a power system. The method comprises the following steps: acquiring a second-order transfer function G(s) of a system VSG control and an improved system transfer function G'(s) after adding a damping link, the system transfer function comprising a damping compensation parameter, then acquiring a system frequency and a storage system SOC, when the storage system SOC is in a first range, adjusting the damping compensation parameter based on an inertia constant and a damping coefficient, and adjusting a system inertia coefficient based on the system frequency, and when the storage system SOC is not in the first range, adjusting the system inertia coefficient based on the storage system SOC. The application can prolong the service life of the storage and improve the operation stability of a "double-high" power grid.

Description

Technical Field

[0001] This invention belongs to the field of stable operation of power systems, and particularly relates to a method, device, electronic equipment and storage medium for suppressing subsynchronous resonance. Background Technology

[0002] With the vigorous development of new energy sources, primarily clean energy such as solar and wind power, my country's power grid has gradually formed a "dual-high" characteristic, containing a high proportion of renewable energy and a high proportion of power electronic equipment. With the development of modern power electronics technology, distributed generation technology based on renewable energy has been widely applied, greatly enhancing the economy and flexibility of power system operation. However, the increased penetration rate of renewable energy has also led to a gradual decrease in the capacity proportion of synchronous generators in the power system, resulting in a significant reduction in the overall inertia of the power system and a decrease in its robustness.

[0003] Virtual Synchronous Generator (VSG) technology effectively improves frequency stability by introducing virtual inertia to simulate the rotor motion behavior of the VSG. However, introducing virtual inertia also reduces system damping, making the VSG prone to active power oscillations. To suppress power oscillations, a common practice is to introduce damping feedback to form an inertia-damped integrated controller for the VSG, simulating the inertia-damping characteristics of a synchronous generator. When the VSG operates in PQ mode, its inertia-damping characteristics determine the system's frequency support capability and the dynamic and static characteristics of active power. A large inertia coefficient enhances the VSG's frequency support capability but increases active power overshoot, leading to longer and more prolonged settling time, while simultaneously reducing system damping and potentially causing power oscillations. Conversely, a large damping coefficient reduces active power overshoot and improves damping, but it can result in larger steady-state active power errors.

[0004] Although various new source, load, and storage interfaces, as well as inertia and frequency support control technologies for DC transmission system converters, can improve the inertial response capability of power systems and reduce the pressure on the safe operation of large power grids, how to estimate the spatiotemporal characteristics of inertia level during the system's inertial response process under the background of "dual high" power systems with high proportions of renewable energy and power electronics, and then adjust the coordination of inertia support responses of various parts of the system to meet various stability constraints and improve the safe and stable operation capability of the system, remains an urgent problem to be solved. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a subsynchronous resonance suppression method, device, electronic device and storage medium to solve the problem that the existing VSG control scheme cannot meet the various stability constraints of the new power system with "high speed and high voltage" characteristics, and that subsynchronous resonance exists.

[0006] In a first aspect, embodiments of the present invention provide a subsynchronous resonance suppression method, comprising:

[0007] Obtain the second-order transfer function G(s) of the system virtual synchronous generator VSG control and the improved system transfer function G'(s) after adding a damping element; wherein, the system transfer function includes damping compensation parameters;

[0008] Acquire system frequency and energy storage system state of charge (SOC);

[0009] When the SOC of the energy storage system is within a first range, the damping compensation parameter is adjusted based on the inertia constant and the damping coefficient, and the system inertia coefficient is adjusted based on the system frequency.

[0010] When the SOC of the energy storage system is not within the first range, the system inertia coefficient is adjusted based on the SOC of the energy storage system.

[0011] In one possible implementation, the damping compensation parameters include a proportional coefficient and a differential coefficient, and the improved system transfer function G'(s) is:

[0012]

[0013] Among them, K pp K is the proportional coefficient of the damping compensation element. PD X represents the differential coefficient of the damping compensation element; g =ωL g X g U is the line-side inductive reactance, i.e., the line inductive reactance from the LC filter outlet to the PCC point; ω is the system angular velocity; U n U represents the AC side voltage amplitude of the inverter. g The amplitude of the PCC AC voltage; L c =L g +L o L c L represents the second-order coefficients of the transfer function; g L is the equivalent inductance of the line. o =(1-J) / K v1 L o K is the open-loop gain of the inner-loop transfer function, and its magnitude represents the output impedance; v1 R is the integral coefficient of the voltage controller PI; J is the system inertia coefficient; g is the equivalent resistance of the line; s is the Laplace operator.

[0014] In one possible implementation, adjusting the damping compensation parameters based on the inertial constant and damping coefficient includes:

[0015] The proportional coefficient and differential coefficient are adjusted based on the aforementioned inertial constant and damping coefficient;

[0016] The expressions for the proportional coefficient and the differential coefficient are as follows:

[0017]

[0018] Among them, K pp K is the proportional coefficient of the damping compensation element. PD X is the differential coefficient of the damping compensation element; D is the damping coefficient; M = Jω, M is the inertial torque; ω is the system angular velocity; J is the system inertia coefficient; k1 and k2 are adjustment coefficients; X g =ωL g X g This refers to the line-side inductive reactance, specifically the line inductive reactance from the LC filter output to the PCC point; U n U represents the AC side voltage amplitude of the inverter. g The amplitude of the PCC AC voltage; L c =L g +L o L c L represents the second-order coefficients of the transfer function; g L is the equivalent inductance of the line. o = (1-H) / K v1 L o K is the open-loop gain of the inner-loop transfer function, and its magnitude represents the output impedance; v1 R is the integral coefficient of the voltage controller PI; g P is the equivalent resistance of the line; n =X g U n U g P n This is the numerator of the system transfer function.

[0019] In one possible implementation, when the SOC of the energy storage system is within a first range, the expression for the system inertia coefficient is:

[0020]

[0021] Where J0 is the magnitude of the system's inertia during normal operation; k5 and k6 are adjustment coefficients; Δk x The parameter adjustment step size; β is the system frequency fluctuation threshold; f is the system frequency; t is time; A is the coefficient of the exponential function;

[0022] The adjustment of the system inertia coefficient based on the system frequency includes: adjusting the exponential function coefficient A in the system inertia coefficient based on the system frequency, with the expression being:

[0023]

[0024] Among them, f m f is the rated frequency; f is the real-time frequency; Δf is the maximum frequency fluctuation limit of the system.

[0025] In one possible implementation, adjusting the system inertia coefficient based on the energy storage system's SOC includes:

[0026] When the SOC of the energy storage system is less than the lower limit of the first range, the system inertia coefficient is:

[0027] J = k3SOC B J0

[0028] Where k3 and B are adjustment coefficients when the SOC of the energy storage system is less than the lower limit of the first range; J0 is the magnitude of the inertia when the system is operating normally.

[0029] In one possible implementation, adjusting the system inertia coefficient based on the energy storage system's SOC includes:

[0030] When the SOC of the energy storage system is greater than the upper limit of the first range, the system inertia coefficient is:

[0031] J = k4(1-SOC) C J0

[0032] Where k4 and C are adjustment coefficients when the SOC of the energy storage system is greater than the upper limit of the first range; J0 is the magnitude of the inertia when the system is running normally.

[0033] In one possible implementation, the expression for the second-order transfer function G(s) is:

[0034]

[0035] Among them, X g =ωL g X g U is the line-side inductive reactance, i.e., the line inductive reactance from the LC filter outlet to the PCC point; ω is the system angular velocity; U n U represents the AC side voltage amplitude of the inverter. g The amplitude of the PCC AC voltage; L c =L g +L o L c L represents the second-order coefficients of the transfer function; g L is the equivalent inductance of the line. o = (1-H) / K v1 L o K is the open-loop gain of the inner-loop transfer function, and its magnitude represents the output impedance; v1R is the integral coefficient of the voltage controller PI; g is the equivalent resistance of the line; s is the Laplace operator.

[0036] Secondly, embodiments of the present invention provide a subsynchronous resonance suppression device, comprising:

[0037] The first acquisition module is used to acquire the second-order transfer function G(s) of the VSG control of the system and the improved system transfer function G'(s) after adding a damping element; wherein, the system transfer function includes damping compensation parameters;

[0038] The second acquisition module is used to acquire the system frequency and the SOC of the energy storage system.

[0039] The adjustment module is configured to adjust the damping compensation parameters based on the inertia constant and damping coefficient, and adjust the system inertia coefficient based on the system frequency, when the SOC of the energy storage system is within a first range; and to adjust the system inertia coefficient based on the SOC of the energy storage system when the SOC of the energy storage system is not within the first range.

[0040] Thirdly, embodiments of the present invention provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the subsynchronous resonance suppression method as described in the first aspect or any possible implementation thereof.

[0041] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the subsynchronous resonance suppression method as described in the first aspect or any possible implementation thereof.

[0042] The beneficial effects of the subsynchronous resonance suppression method provided in this invention are as follows:

[0043] This invention obtains the second-order transfer function G(s) of the VSG control system and the improved system transfer function G'(s) after adding a damping element, and obtains the system frequency and the SOC of the energy storage system. It provides different control strategies considering the range of the energy storage system SOC. The system transfer function includes damping compensation parameters. When the energy storage system SOC is within a first range, adjusting the damping compensation parameters based on the energy storage system SOC can suppress the amplitude of resonance spikes, increase the stability margin, and achieve damping compensation. Furthermore, considering the range of the energy storage system SOC, the system inertia coefficient is adjusted based on the system frequency to provide support for the system frequency, improving the operational stability of the "high-voltage and high-efficiency" power grid and avoiding subsynchronous oscillations. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is an application scenario diagram of a subsynchronous resonance suppression method provided in an embodiment of the present invention;

[0046] Figure 2 This is a flowchart illustrating the implementation of a subsynchronous resonance suppression method provided in an embodiment of the present invention.

[0047] Figure 3 This is a block diagram of the control structure of the damping compensation link provided in the embodiment of the present invention;

[0048] Figure 4 This is a model topology diagram of the distributed generation-energy storage system provided in the embodiment of the present invention for simulation verification;

[0049] Figure 5 This is a comparison of Bode plots before and after adding damping compensation to the traditional VSG control provided in this embodiment of the invention;

[0050] Figure 6 This is an embodiment of the invention showing the system frequency variation when using conventional VSG control;

[0051] Figure 7 This is the system frequency change after adaptive damping compensation provided in the embodiments of the present invention;

[0052] Figure 8 This is a schematic diagram of a subsynchronous resonance suppression device provided in an embodiment of the present invention;

[0053] Figure 9 This is a schematic diagram of a subsynchronous resonance suppression electronic device provided in an embodiment of the present invention. Detailed Implementation

[0054] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0055] Analyze the changes in inertia of traditional power grids and "high-voltage" power grids in terms of themselves and their control.

[0056] Analyzing the system inertia from the perspective of new energy sources connected to the grid and their control, the relationship between traditional droop control and traditional VSG control is as follows:

[0057]

[0058] Among them, P in P represents the shaft power of the synchronous generator. out ω represents the power generation capacity; J is the system inertia coefficient; D is the system damping coefficient; ω m ω is the rotor angular velocity; ω0 is the reference angular velocity (rated angular velocity); ω g k is the angular frequency of the power grid. p This is the droop coefficient.

[0059] Traditional VSG control is prone to active power oscillations. This invention analyzes the resonance spikes and subsynchronous oscillations in "high-voltage and high-efficiency" power grids under traditional VSG control. Based on this, this invention provides a subsynchronous resonance suppression method, which aims to solve the problem that VSG control schemes cannot meet various stability constraints in new power systems with "high-voltage and high-efficiency" characteristics.

[0060] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0061] See Figure 1 The diagram illustrates an application scenario of a subsynchronous resonance suppression method provided by an embodiment of the present invention, such as... Figure 1 As shown, the inverter of the photovoltaic-storage unit includes LC filter stages Lf and Cf, and switching devices Sa1, Sb1, Sc1, Sa2, Sb2, and Sc2. The control strategy of the photovoltaic-storage unit inverter adopts a subsynchronous oscillation damping compensation strategy and an adaptive control method. The photovoltaic array is a photovoltaic power generation device, and the battery is an energy storage device. Both are connected to the DC bus via DC / DC converters and then connected to the system via DC / AC inverters. LC filtering is performed by switching device control, and damping compensation and virtual inertia control are performed by power calculation and voltage reference value calculation, i.e., adjusting the system damping compensation parameters and the system inertia coefficient. The synchronous generator G1 is connected to the inductor Lg and the load Z. load Between these, it is used to meet power supply needs. The main application scenario of this invention is to address the problems of low inertia and resonance spikes brought about by the connection of new energy power generation devices, represented by photovoltaic energy storage units, to AC main grids or microgrids. By improving the inverter control strategy of photovoltaic energy storage units, the system stability and service life of energy storage units are improved.

[0062] See Figure 2 The diagram illustrates a flowchart of a subsynchronous resonance suppression method provided by an embodiment of the present invention, which includes the following steps:

[0063] S201. Obtain the second-order transfer function G(s) of the VSG control system and the improved system transfer function G'(s) after adding a damping element; wherein, the system transfer function includes the damping compensation parameters.

[0064] In one possible implementation, the second-order transfer function G(s) is improved by adding damping compensation parameters to its expression, resulting in the improved system transfer function G'(s). The damping compensation parameters include proportional and differential coefficients. The expression for the original second-order transfer function G(s) is:

[0065]

[0066] Among them, X g =ωL g X g U is the line-side inductive reactance, i.e., the line inductive reactance from the LC filter outlet to the PCC point; ω is the system angular velocity; U n U represents the AC side voltage amplitude of the inverter. g The amplitude of the PCC AC voltage; L c =L g +L o L c L represents the second-order coefficients of the transfer function; g L is the equivalent inductance of the line. o = (1-H) / K v1 L o K is the open-loop gain of the inner-loop transfer function, and its magnitude represents the output impedance; v1 R is the integral coefficient of the voltage controller PI; g is the equivalent resistance of the line; s is the Laplace operator.

[0067] The improved system transfer function G'(s) is:

[0068]

[0069] Among them, K pp K is the proportional coefficient of the damping compensation element. PD X represents the differential coefficient of the damping compensation element; g =ωL g X g U is the line-side inductive reactance, i.e., the line inductive reactance from the LC filter outlet to the PCC point; ω is the system angular velocity; U n U represents the AC side voltage amplitude of the inverter. g The amplitude of the PCC AC voltage; L c =L g +L o Lc is the second-order coefficient of the transfer function; L g is the equivalent inductance of the line; L o =(1-J) / K v1 , L o is the open-loop gain of the inner-loop transfer function, the amplitude of which represents the magnitude of the output impedance; K v1 is the integral coefficient of the PI voltage controller; J is the system inertia coefficient; R g is the equivalent resistance of the line; s is the Laplace operator.

[0070] In the embodiment of the present invention, a damping compensation strategy based on output power is proposed. By acquiring the second-order transfer function G(s) of the system VSG control, and improving G(s) by adding a damping link, the improved system transfer function G'(s) is obtained. While maintaining the system characteristics almost unchanged, the amplitude of the resonance peak is suppressed, and the stability margin is increased, so as to realize damping compensation.

[0071] S202. Acquire the system frequency and the state of charge SOC of the energy storage system.

[0072] In a possible implementation, acquiring the SOC of the energy storage system specifically refers to acquiring the SOC state of the energy storage device in the energy storage system, and dividing the SOC state of the energy storage device into three states: over-discharge warning, safe charging and discharging, and over-charge warning. Optionally, the range corresponding to the over-discharge warning state is SOC<20%, the range corresponding to the safe charging and discharging state is 20%≤SOC≤90%, and the range corresponding to the over-charge warning state is SOC>90%.

[0073] In the embodiment of the present invention, both over-charge and over-discharge of energy storage will lead to a significant reduction in the service life of the energy storage, that is, when the SOC of the energy storage system exceeds the critical constraint of charging and discharging, there is a risk of causing a significant reduction in the service life of the energy storage. Therefore, comprehensively considering the change speed and change degree of the system frequency, and determining a targeted sub-synchronous resonance suppression strategy based on different SOC ranges of the energy storage system, is beneficial to comprehensively improve the stability of the new power system with the "double high" characteristics.

[0074] S203. When the SOC of the energy storage system is in the first range, adjust the damping compensation parameter based on the inertia constant and the damping coefficient, and adjust the system inertia coefficient based on the system frequency.

[0075] In the embodiment of the present invention, that the SOC of the energy storage system is in the first range means that the energy storage device is in a safe charging and discharging state. Optionally, the first range is 20%<SOC<90%, the inertia constant and the inertia coefficient are adjusted to obtain the damping ratio compensation parameter, the damping compensation parameter includes a proportional coefficient and a differential coefficient, and the system frequency is adjusted to obtain the system inertia coefficient.

[0076] In one possible implementation, the proportional coefficient and differential coefficient in the damping compensation parameters are expressed as follows:

[0077]

[0078] Among them, K pp K is the proportional coefficient of the damping compensation element. PD X is the differential coefficient of the damping compensation element; D is the damping coefficient; M = Jω, M is the inertial torque; ω is the system angular velocity; J is the system inertia coefficient; k1 and k2 are adjustment coefficients; X g =ωL g X g This refers to the line-side inductive reactance, specifically the line inductive reactance from the LC filter output to the PCC point; U n U represents the AC side voltage amplitude of the inverter. g The amplitude of the PCC AC voltage; L c =L g +L o L c L represents the second-order coefficients of the transfer function; g L is the equivalent inductance of the line. o = (1-H) / K v1 L o K is the open-loop gain of the inner-loop transfer function, and its magnitude represents the output impedance; v1 R is the integral coefficient of the voltage controller PI; g P is the equivalent resistance of the line; n =X g U n U g P n This is the numerator of the system transfer function.

[0079] See Figure 3 It shows a block diagram of the control structure of the damping compensation link provided in an embodiment of the present invention, U o The voltage and current at the LC output of the inverter (equivalent to U) n ), I o The current at the inverter LC output (I) n ), P ref The rated active power of the inverter (equivalent to P) in ), P e The inverter output power (equivalent to P) out ), θ is the output phase angle; U * The system voltage reference value (equivalent to U) g ), This is the reference value for the d-axis voltage output by the controller. K is the reference value for the q-axis voltage output by the controller. ppK is the proportional coefficient of the damping compensation element. PD Here, D is the differential coefficient of the damping compensation element, M is the damping coefficient, and X is the torque. g For the line-side inductive reactance, U n U represents the AC side voltage amplitude of the inverter. g R is the amplitude of the PCC AC voltage. g Let be the equivalent resistance of the line, and s be the Laplace operator.

[0080] In one possible implementation, considering the system frequency variation, the expression for the system inertia coefficient is:

[0081]

[0082] Where J0 is the magnitude of the system's inertia during normal operation; k5 and k6 are adjustment coefficients; Δk x The parameter adjustment step size is β, the system frequency fluctuation threshold is f, the system frequency is t, the time is A, and the coefficient of the exponential function is A.

[0083] In this embodiment of the invention, the system inertia J can be rapidly adjusted according to the degree of change in system frequency. That is, when the system frequency exceeds the maximum fluctuation value, J will increase rapidly with the increase of the power function exponent. By increasing the adaptive exponent, the inertia is increased, which provides support for the system frequency and improves the inertia level of the system.

[0084] The exponential function coefficient A in the system inertia coefficient is determined by the difference in the degree of change of the system frequency:

[0085]

[0086] Among them, f m f is the rated frequency; f is the real-time frequency; Δf is the maximum frequency fluctuation limit of the system.

[0087] In this embodiment of the invention, considering the system frequency change, on the one hand, an exponential function with the system frequency change rate as the core is established, combined with an adjustment coefficient, to provide a larger inertia for the system when the frequency change rate is large, and a smaller inertia for the system when the frequency change rate is small; on the other hand, the exponential function coefficient determined by the difference between the real-time frequency and the rated frequency, combined with the adjustment step size, will increase the inertia by increasing the adaptive exponent when the system frequency change value exceeds the set value, thereby providing support for the system frequency and improving the operational stability of the "high-voltage and high-efficiency" power grid.

[0088] S204. When the SOC of the energy storage system is not within the first range, adjust the system inertia coefficient based on the SOC of the energy storage system.

[0089] In the embodiments of the present invention, when the SOC of the energy storage system is not within the first range, if the SOC is less than the lower limit of the first range, the energy storage device is in an over-discharge warning state at this time; if the SOC is greater than the upper limit of the first range, the energy storage device is in an over-charge warning state at this time. Optionally, the range corresponding to the over-discharge warning state is SOC < 20%, and the range corresponding to the over-charge warning state is SOC > 90%. Continuing to discharge or charge the energy storage device in these two states will greatly reduce its service life. Therefore, the inertia support it provides to the system, that is, the system inertia coefficient, needs to be adjusted according to the SOC of the energy storage system.

[0090] In a possible implementation, when the SOC of the energy storage system is less than the lower limit of the first range, the system inertia coefficient is:

[0091] J=k3SOC B J0

[0092] wherein k3 and B are adjustment coefficients when the SOC of the energy storage system is less than the lower limit of the first range; J0 is the inertia of the system during normal operation.

[0093] In a possible implementation, when the SOC of the energy storage system is greater than the upper limit of the first range, the system inertia coefficient is:

[0094] J=k4(1-SOC) C J0

[0095] wherein k4 and C are adjustment coefficients when the SOC of the energy storage system is greater than the upper limit of the first range; J0 is the inertia of the system during normal operation.

[0096] In this embodiment, the second-order transfer function G(s) of the system VSG control and the transfer function G'(s) of the improved system after adding the damping link are acquired. The system transfer function includes a damping compensation parameter. Different control strategies are provided by comprehensively considering the system frequency and the SOC of the energy storage system. When the SOC of the energy storage system is within the first range, the damping compensation parameter is adjusted based on the inertia constant and the damping coefficient, and the system inertia coefficient is adjusted based on the system frequency. When the SOC of the energy storage system is not within the first range, the system inertia coefficient is adjusted based on the SOC of the energy storage system, which provides inertia support for the system frequency and improves the operation stability of the "high proportion of renewable energy and high proportion of power electronic equipment" power grid.

[0097] In a specific embodiment, the first range of the SOC of the energy storage system is 20% < SOC < 90%, the lower limit of the first range is 20%, and the upper limit of the first range is 90%. Correspondingly, the expressions of the system inertia coefficient under different SOCs are as follows:

[0098]

[0099] Wherein, k3 and B are adjustment coefficients when the SOC of the energy storage system is less than 20%; k4 and C are adjustment coefficients when the SOC of the energy storage system is greater than 90%; k5 and k6 are adjustment coefficients when the SOC of the energy storage system is in the range of 20%≤SOC≤90%; and J0 is the magnitude of the inertia when the system is operating normally.

[0100] See Figure 4 It shows a model topology diagram of a distributed generation-energy storage system provided by an embodiment of the present invention for simulation verification, such as... Figure 4 As shown, the four-terminal AC photovoltaic-storage microgrid system mainly consists of four parts: photovoltaic and storage units, synchronous generator G1, and loads. The overall topology is as follows: Figure 4 As shown in the diagram. The photovoltaic-storage unit includes an energy storage device and a distributed generation device. The inverter on the grid-connected side of the photovoltaic-storage unit adopts a VSG control strategy. The distributed generation device is a photovoltaic power generation unit, which adopts a constant power control mode. The energy storage device maintains the bidirectional flow of energy in the system. The photovoltaic power generation device and the energy storage device are respectively connected to the DC bus via DC / DC converters and then connected to the system via DC / AC inverters. The synchronous generator G1 operates in a constant power model to maintain the basic power supply requirements of the load. The load side is a constant power load.

[0101] See Figure 5 It shows a comparison of Bode plots before and after adding damping compensation to the conventional VSG control provided in the embodiments of the present invention, such as... Figure 5 As shown, it illustrates the changes in amplitude and phase of the system with respect to system frequency before and after adding damping compensation to the traditional VSG control. It can be seen that before adding damping compensation to the traditional VSG control, the system exhibits resonant spikes and subsynchronous resonance phenomena. After adding the damping compensation stage, the amplitude of the resonant spikes and the subsynchronous oscillation phenomenon are suppressed.

[0102] The subsynchronous resonance suppression method of the present invention is illustrated below with an embodiment. In this embodiment, the damping compensation strategy and parameter adaptive control method are specifically illustrated using a photovoltaic energy storage device connected to the power distribution network as a simulation object.

[0103] In this example, the frequency change of the AC bus of the system connected to the load is considered at 0.5s under normal SOC conditions for the energy storage element. The actual effects of the traditional VSG control method and the damping compensation method proposed in this paper are compared. In this example, the adjustment coefficients in the adaptive parameters are: adjustment coefficient k1 = 2; adjustment coefficient k2 = 5; parameter adjustment step size is Δk. x =8; the system frequency fluctuation threshold is β = 0.5; the maximum system frequency fluctuation limit is Δf = 0.02; the proportional coefficient of the damping compensation element is K. pp =3×10 -5 The differential coefficient of the damping compensation element is K. PD =5×10-5 The simulation results are as follows: Figure 5 and Figure 6 As shown.

[0104] See Figure 6 and Figure 7 , Figure 6 The following is an illustration of the system frequency variation when using conventional VSG control, as provided in an embodiment of the present invention. Figure 7 The diagram illustrates the frequency variation of the system after adaptive damping compensation, as provided in an embodiment of the present invention.

[0105] In an embodiment of the present invention, Figure 6 and Figure 7 In comparison, it can be seen that the method proposed in this invention effectively improves system damping and suppresses frequency oscillation when the system load changes, making the new steady-state frequency value of the system closer to the rated frequency and with a smaller degree of change.

[0106] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not limit the implementation process of the embodiments of the present invention.

[0107] The following are embodiments of the apparatus of the present invention. For details not described herein, please refer to the above-described method embodiments.

[0108] Figure 8 The diagram shows a structural schematic of a subsynchronous resonance suppression device according to an embodiment of the present invention. For ease of explanation, only the parts related to the embodiment of the present invention are shown, such as... Figure 8 The subsynchronous resonance suppression device shown includes: a first acquisition module 801, a second acquisition module 802, and an adjustment module 803.

[0109] The first acquisition module 801 is used to acquire the second-order transfer function G(s) of the VSG control of the system and the improved system transfer function G'(s) after adding a damping element; wherein the system transfer function includes damping compensation parameters.

[0110] The second acquisition module 802 is used to acquire the system frequency and the SOC of the energy storage system.

[0111] When the SOC of the energy storage system is within the first range, the adjustment module 803 is used to adjust the damping compensation parameters based on the inertia constant and damping coefficient, and to adjust the system inertia coefficient based on the system frequency; when the SOC of the energy storage system is not within the first range, the adjustment module 803 is used to adjust the system inertia coefficient based on the SOC of the energy storage system.

[0112] In one possible implementation, the first acquisition module 801 is specifically used for: the system transfer function including damping compensation parameters; the damping compensation parameters including proportional coefficients and differential coefficients; and improving the system transfer function G'(s) as:

[0113]

[0114] Among them, K pp K is the proportional coefficient of the damping compensation element. PD X represents the differential coefficient of the damping compensation element; g =ωL g X g U is the line-side inductive reactance, i.e., the line inductive reactance from the LC filter outlet to the PCC point; ω is the system angular velocity; U n U represents the AC side voltage amplitude of the inverter. g The amplitude of the PCC AC voltage; L c =L g +L o L c L represents the second-order coefficients of the transfer function; g L is the equivalent inductance of the line. o =(1-J) / K v1 L o K is the open-loop gain of the inner-loop transfer function, and its magnitude represents the output impedance; v1 R is the integral coefficient of the voltage controller PI; J is the system inertia coefficient; g is the equivalent resistance of the line; s is the Laplace operator.

[0115] In one possible implementation, the first acquisition module 801 is specifically used to: adjust the damping compensation parameters based on the inertial constant and the damping coefficient, including:

[0116] Adjust the proportional coefficient and differential coefficient based on the inertial constant and damping coefficient;

[0117] The expressions for the proportionality coefficient and the differential coefficient are as follows:

[0118]

[0119] Among them, K pp K is the proportional coefficient of the damping compensation element. PD X is the differential coefficient of the damping compensation element; D is the damping coefficient; M = Jω, M is the inertial torque; ω is the system angular velocity; J is the system inertia coefficient; k1 and k2 are adjustment coefficients; X g =ωL g X g This refers to the line-side inductive reactance, specifically the line inductive reactance from the LC filter output to the PCC point; U n U represents the AC side voltage amplitude of the inverter.g The amplitude of the PCC AC voltage; L c =L g +L o L c L represents the second-order coefficients of the transfer function; g L is the equivalent inductance of the line. o = (1-H) / K v1 L o K is the open-loop gain of the inner-loop transfer function, and its magnitude represents the output impedance; v1 R is the integral coefficient of the voltage controller PI; g P is the equivalent resistance of the line; n =X g U n U g P n This is the numerator of the system transfer function.

[0120] In one possible implementation, the first acquisition module 801 is specifically used for: the expression of the second-order transfer function G(s) is:

[0121]

[0122] Among them, X g =ωL g X g U is the line-side inductive reactance, i.e., the line inductive reactance from the LC filter outlet to the PCC point; ω is the system angular velocity; U n U represents the AC side voltage amplitude of the inverter. g The amplitude of the PCC AC voltage; L c =L g +L o L c L represents the second-order coefficients of the transfer function; g L is the equivalent inductance of the line. o = (1-H) / K v1 L o K is the open-loop gain of the inner-loop transfer function, and its magnitude represents the output impedance; v1 R is the integral coefficient of the voltage controller PI; g is the equivalent resistance of the line; s is the Laplace operator.

[0123] In one possible implementation, the adjustment module 803 is specifically used to: when the SOC of the energy storage system is within a first range, the expression for the system inertia coefficient is:

[0124]

[0125] Where J0 is the magnitude of the system's inertia during normal operation; k5 and k6 are adjustment coefficients; Δkx The parameter adjustment step size is β, the system frequency fluctuation threshold is f, the system frequency is t, the time is A, and the coefficient of the exponential function is A.

[0126] Adjusting the system inertia coefficient based on the system frequency includes: adjusting the exponential function coefficient A in the system inertia coefficient based on the system frequency, with the expression:

[0127]

[0128] Among them, f m f is the rated frequency; f is the real-time frequency; Δf is the maximum frequency fluctuation limit of the system.

[0129] In one possible implementation, the adjustment module 803 is specifically used to: adjust the system inertia coefficient based on the energy storage system's SOC, including:

[0130] When the SOC of the energy storage system is less than the lower limit of the first range, the system inertia coefficient is:

[0131] J = k3SOC B J0

[0132] Where k3 and B are adjustment coefficients when the SOC of the energy storage system is less than the lower limit of the first range; J0 is the magnitude of the inertia when the system is operating normally.

[0133] In one possible implementation, the adjustment module 803 is specifically used to: adjust the system inertia coefficient based on the energy storage system's SOC, including:

[0134] When the SOC of the energy storage system is greater than the upper limit of the first range, the system inertia coefficient is:

[0135] J = k4(1-SOC) C J0

[0136] Where k4 and C are adjustment coefficients when the SOC of the energy storage system is greater than the upper limit of the first range; J0 is the magnitude of the inertia when the system is running normally.

[0137] As can be seen from the above, the subsynchronous resonance suppression method provided in this embodiment of the invention first obtains the second-order transfer function G(s) of the system VSG control and the improved system transfer function G'(s) after adding a damping element. The system transfer function includes damping compensation parameters. Then, it obtains the system frequency and the SOC of the energy storage system. When the SOC of the energy storage system is within a first range, the damping compensation parameters are adjusted based on the inertia constant and the damping coefficient, and the system inertia coefficient is adjusted based on the system frequency. When the SOC of the energy storage system is not within the first range, the system inertia coefficient is adjusted based on the SOC of the energy storage system. This embodiment comprehensively considers the system frequency and the SOC of the energy storage system, suppresses the subsynchronous resonance phenomenon of the system, and improves the operational stability of the "high-voltage and high-efficiency" power grid.

[0138] See Figure 9 This illustrates a schematic diagram of an electronic device provided by an embodiment of the present invention. For example... Figure 9 As shown, the electronic device 9 of this embodiment includes: a processor 90, a memory 91, and a computer program 92 stored in the memory 91 and executable on the processor 90. When the processor 90 executes the computer program 92, it implements the steps in the various embodiments of the subsynchronous resonance suppression method described above, for example... Figure 2 Steps S201 to S204 are shown. Alternatively, when the processor 90 executes the computer program 92, it implements the functions of each module / unit in the above-described device embodiments, for example... Figure 8 The functions of modules 801 to 803 are shown.

[0139] For example, the computer program 92 can be divided into one or more modules / units, which are stored in the memory 91 and executed by the processor 90 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 92 in the electronic device 9. For example, the computer program 92 can be divided into... Figure 8 The modules shown are 801 to 803.

[0140] The electronic device 9 can be a desktop computer, laptop, handheld computer, or cloud server, etc. The electronic device 9 may include, but is not limited to, a processor 90 and a memory 91. Those skilled in the art will understand that... Figure 9 This is merely an example of electronic device 9 and does not constitute a limitation on electronic device 9. It may include more or fewer components than shown, or combine certain components, or different components. For example, the electronic device may also include input / output devices, network access devices, buses, etc.

[0141] The processor 90 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0142] The memory 91 can be an internal storage unit of the electronic device 9, such as a hard disk or memory. The memory 91 can also be an external storage device of the electronic device 9, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, the memory 91 can include both internal and external storage units of the electronic device 9. The memory 91 is used to store the computer program and other programs and data required by the electronic device. The memory 91 can also be used to temporarily store data that has been output or will be output.

[0143] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0144] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0145] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0146] In the embodiments provided by this invention, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0147] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0148] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0149] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various subsynchronous resonance suppression method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0150] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for suppressing subsynchronous resonance, characterized in that, include: Obtain the second-order transfer function of the system's virtual synchronous generator VSG control. And the improved system transfer function after adding damping elements The improved system transfer function includes damping compensation parameters. Obtain the system frequency and the state of charge (SOC) of the energy storage system; When the SOC of the energy storage system is within a first range, the damping compensation parameter is adjusted based on the system inertia coefficient and the damping coefficient, and the system inertia coefficient is adjusted based on the system frequency; wherein, the first range is used to indicate that the energy storage system is in a safe charging and discharging state; When the SOC of the energy storage system is not within the first range, the system inertia coefficient is adjusted based on the SOC of the energy storage system. The damping compensation parameters include proportional coefficient and derivative coefficient; the improved system transfer function for: in, This is the proportional coefficient for the damping compensation element; For the differential coefficients of the damping compensation element; , For line-side inductive reactance; The system angular velocity; This refers to the AC side voltage amplitude of the inverter. This refers to the amplitude of the PCC AC voltage. , These are the second-order coefficients of the transfer function; This is the equivalent inductance of the line; , The open-loop gain is the inner-loop transfer function, and its magnitude represents the output impedance. The integral coefficient of the voltage controller PI; The system inertia coefficient; This is the equivalent resistance of the line; For the Laplace operator; The adjustment of the damping compensation parameters based on the system inertia coefficient and damping coefficient includes: Adjust the proportional coefficient and differential coefficient based on the system inertia coefficient and the damping coefficient; The expressions for the proportionality coefficient and the differential coefficient are as follows: in, This is the proportional coefficient for the damping compensation element; For the differential coefficients of the damping compensation element; The damping coefficient; , It is the inertial torque; The system angular velocity; The system inertia coefficient; and For adjustment coefficients; , This refers to the line-side inductive reactance, i.e., the line inductive reactance from the LC filter outlet to the PCC point. This refers to the AC side voltage amplitude of the inverter. This refers to the amplitude of the PCC AC voltage. , These are the second-order coefficients of the transfer function; This is the equivalent inductance of the line; , The open-loop gain is the inner-loop transfer function, and its magnitude represents the output impedance. The integral coefficient of the voltage controller PI; This is the equivalent resistance of the line; , This is the numerator of the system transfer function.

2. The subsynchronous resonance suppression method according to claim 1, characterized in that, When the SOC of the energy storage system is within the first range, the expression for the system inertia coefficient is: in, This represents the magnitude of the system's inertia during normal operation. and For adjustment coefficients; Adjust the step size for the parameters; This is the system frequency fluctuation threshold; For system frequency; For time; The coefficients are those of the exponential function. The adjustment of the system inertia coefficient based on the system frequency includes: adjusting the exponential function coefficient in the system inertia coefficient based on the system frequency. The expression is: in, The rated frequency; For real-time frequency; Limit the maximum fluctuation value of the system frequency.

3. The subsynchronous resonance suppression method according to claim 1, characterized in that, The adjustment of the system inertia coefficient based on the SOC of the energy storage system includes: When the SOC of the energy storage system is less than the lower limit of the first range, the system inertia coefficient is: in, and This is an adjustment factor when the SOC of the energy storage system is less than the lower limit of the first range; This represents the inertia of the system during normal operation.

4. The subsynchronous resonance suppression method according to claim 1, characterized in that, The adjustment of the system inertia coefficient based on the SOC of the energy storage system includes: When the SOC of the energy storage system is greater than the upper limit of the first range, the system inertia coefficient is: in, and This is an adjustment factor when the SOC of the energy storage system is greater than the upper limit of the first range; This represents the inertia of the system during normal operation.

5. The subsynchronous resonance suppression method according to claim 1, characterized in that, The second-order transfer function The expression is: in, , This refers to the line-side inductive reactance, i.e., the line inductive reactance from the LC filter outlet to the PCC point. The system angular velocity; This refers to the AC side voltage amplitude of the inverter. This refers to the amplitude of the PCC AC voltage. , These are the second-order coefficients of the transfer function; This is the equivalent inductance of the line; , The system inertia coefficient; The open-loop gain is the inner-loop transfer function, and its magnitude represents the output impedance. The integral coefficient of the voltage controller PI; This is the equivalent resistance of the line; For the Laplace operator.

6. A subsynchronous resonance suppression device, characterized in that, include: The first acquisition module is used to acquire the second-order transfer function of the system's VSG control. And the improved system transfer function after adding damping elements The improved system transfer function includes damping compensation parameters. The second acquisition module is used to acquire the system frequency and the SOC of the energy storage system. The adjustment module, when the SOC of the energy storage system is within a first range, adjusts the damping compensation parameter based on the system inertia coefficient and damping coefficient, and adjusts the system inertia coefficient based on the system frequency; wherein, the first range is used to indicate that the energy storage system is in a safe charging and discharging state; when the SOC of the energy storage system is not within the first range, the adjustment module adjusts the system inertia coefficient based on the SOC of the energy storage system. The damping compensation parameters include proportional coefficient and derivative coefficient; the improved system transfer function for: in, This is the proportional coefficient for the damping compensation element; For the differential coefficients of the damping compensation element; , For line-side inductive reactance; The system angular velocity; This refers to the AC side voltage amplitude of the inverter. This refers to the amplitude of the PCC AC voltage. , These are the second-order coefficients of the transfer function; This is the equivalent inductance of the line; , The open-loop gain is the inner-loop transfer function, and its magnitude represents the output impedance. The integral coefficient of the voltage controller PI; The system inertia coefficient; This is the equivalent resistance of the line; For the Laplace operator; The adjustment module is specifically used to: adjust the proportional coefficient and the derivative coefficient based on the system inertia coefficient and the damping coefficient; The expressions for the proportionality coefficient and the differential coefficient are as follows: in, This is the proportional coefficient for the damping compensation element; For the differential coefficients of the damping compensation element; The damping coefficient; , It is the inertial torque; The system angular velocity; The system inertia coefficient; and For adjustment coefficients; , This refers to the line-side inductive reactance, i.e., the line inductive reactance from the LC filter outlet to the PCC point. This refers to the AC side voltage amplitude of the inverter. This refers to the amplitude of the PCC AC voltage. , These are the second-order coefficients of the transfer function; This is the equivalent inductance of the line; , The open-loop gain is the inner-loop transfer function, and its magnitude represents the output impedance. The integral coefficient of the voltage controller PI; This is the equivalent resistance of the line; , This is the numerator of the system transfer function.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the subsynchronous resonance suppression method as described in any one of claims 1 to 5.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the subsynchronous resonance suppression method as described in any one of claims 1 to 5 above.

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