A method and system for determining the equivalent power of a supercapacitor

Abstract

The present application discloses a method and system for determining the equivalent power of a supercapacitor. The method includes: determining the steady-state point of the DC voltage and the target power disturbance size under the DC voltage droop control, and determining the steady-state voltage point after the power disturbance according to the steady-state point of the DC voltage, the target power disturbance size and the DC voltage droop coefficient; determining the quantitative relationship between the supercapacitor voltage and the DC bus voltage according to the control of the supercapacitor; according to the energy conservation relationship, the energy released before and after the supercapacitor power disturbance is equivalent to the equivalent capacitor on the DC bus; determining the equivalent capacitance according to the steady-state voltage point, the quantitative relationship and the equivalent capacitor; performing mathematical modeling according to the equivalent capacitance to obtain the equivalent power of the supercapacitor.

Description

Technical Field

[0001] The present application relates to the technical field of supercapacitors, and in particular to a method and system for determining the equivalent power of a supercapacitor. Background Art

[0002] The rapid development of renewable energy has increasingly highlighted the advantages of DC microgrids, while the high degree of power electronics has resulted in low inertia in DC microgrids and poor anti-disturbance capabilities, which poses certain safety risks to the safe operation of the system. The existing mainstream solution relies on power-type energy storage, such as supercapacitor systems, to increase the inertia of the system and enhance anti-disturbance capabilities. However, although the control of supercapacitors is different, a corresponding mathematical model needs to be established when analyzing the dynamic impact on the system. However, when analyzing the impact of supercapacitor systems on the system, most of the existing modeling methods linearize the system at a certain steady-state point to obtain the mathematical model of the system. The capacitor under virtual capacitor control is linearized to obtain a small signal model, and when analyzing the impact of supercapacitor terminal voltage on system stability, a certain steady-state point of the capacitor voltage is selected for linearization to obtain the small signal model of the system. This modeling method can analyze the impact of the supercapacitor system on the system within a certain range near the steady-state point, and is suitable for small power disturbance analysis.

[0003] However, in the DC system, it is generally believed that the system can bear small power disturbances alone, and more attention is paid to the dynamic performance of the system under large power disturbances. For different control methods of supercapacitors, the quantitative relationship between the supercapacitor voltage and the DC bus voltage may be linear or nonlinear. When it is a linear relationship, the linearized model can also be used to analyze large power disturbances, because its input does not affect the dynamic performance of the output. However, when it is a nonlinear function, if the system power disturbance is large, the results obtained from the small power disturbance analysis cannot be applied to the large power disturbance at this time, which may cause problems such as voltage drop exceeding the limit or dynamic performance not meeting the system requirements.

[0004] In view of the technical problem existing in the above-mentioned prior art that when the quantitative relationship between the supercapacitor voltage and the DC bus voltage is a nonlinear function, if the system power disturbance is large at this time, the result obtained from the small power disturbance analysis cannot be applied to the large power disturbance at this time, which may cause the voltage to drop beyond the limit or the dynamic performance to fail to meet the system requirements, etc., no effective solution has been proposed so far. Summary of the invention

[0005] The embodiments of the present disclosure provide a method and system for determining the equivalent power of a supercapacitor, so as to at least solve the technical problem in the prior art that when the quantitative relationship between the supercapacitor voltage and the DC bus voltage is a nonlinear function, if the system power disturbance is large at this time, the result obtained by the small power disturbance analysis cannot be applied to the large power disturbance at this time, which may cause the voltage to drop beyond the limit or the dynamic performance to fail to meet the system requirements.

[0006] According to one aspect of an embodiment of the present disclosure, a method for determining the equivalent power of a supercapacitor is provided, comprising: determining a steady-state point of a DC voltage and a target power disturbance magnitude under DC voltage droop control, and determining a steady-state voltage point after power disturbance according to the steady-state point of the DC voltage, the target power disturbance magnitude and the DC voltage droop coefficient; determining a quantitative relationship between a supercapacitor voltage and a DC bus voltage according to the control of the supercapacitor; according to the energy conservation relationship, equating the energy released before and after the supercapacitor power disturbance to an equivalent capacitor on the DC bus; determining an equivalent capacitor according to the steady-state voltage point, the quantitative relationship and the equivalent capacitor; and performing mathematical modeling based on the equivalent capacitor to obtain the equivalent power of the supercapacitor.

[0007] According to another aspect of the embodiment of the present disclosure, a system for determining the equivalent power of a supercapacitor is also provided, including: a steady-state voltage point determination module, which is used to determine the steady-state point of the DC voltage and the target power disturbance size under the DC voltage droop control, and determine the steady-state voltage point after the power disturbance according to the steady-state point of the DC voltage, the target power disturbance size and the DC voltage droop coefficient; a quantitative relationship determination module, which is used to determine the quantitative relationship between the supercapacitor voltage and the DC bus voltage according to the control of the supercapacitor; a equivalent capacitor determination module, which is used to equate the energy released before and after the supercapacitor power disturbance to an equivalent capacitor on the DC bus according to the energy conservation relationship; a equivalent capacitor determination module, which is used to determine the equivalent capacitance according to the steady-state voltage point, the quantitative relationship and the equivalent capacitor; and a supercapacitor equivalent power acquisition module, which is used to perform mathematical modeling based on the equivalent capacitance to obtain the supercapacitor equivalent power.

[0008] In the present invention, according to a method for determining the equivalent power of a supercapacitor, regardless of whether the quantitative relationship between the supercapacitor voltage and the DC voltage is linear, the supercapacitor system can be equivalent to an equivalent capacitor on the DC bus, and the capacitance can be adjusted according to the disturbance value to be analyzed, so that the mathematical model can be applied to the analysis of small power disturbances. It can be applied to the dynamic performance analysis of the DC system by the supercapacitor system, and is suitable for analyzing both large power disturbances and small power disturbances, and has certain advantages over the conventional small signal linearization model that can only analyze small power disturbances. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings described herein are used to provide a further understanding of the present disclosure and constitute a part of the present application. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure. In the drawings:

[0010] Figure 1 is a flow chart of a method for determining the equivalent power of a supercapacitor according to an embodiment of the present disclosure;

[0011] Figure 2 is a structural diagram of a DC system grid-connected to a supercapacitor according to an embodiment of the present disclosure;

[0012] Figure 3 is a VSC control block diagram according to an embodiment of the present disclosure;

[0013] Figure 4 is a supercapacitor control block diagram according to an embodiment of the present disclosure;

[0014] Figure 5 is a schematic diagram of modeling a supercapacitor according to an embodiment of the present disclosure;

[0015] Figure 6 is a schematic diagram of a mathematical model according to an embodiment of the present disclosure;

[0016] Figure 7 is a schematic diagram of comparison between a mathematical model, a conventional steady-state point linearized small signal model and a switch model simulation according to the modeling method described in an embodiment of the present disclosure; and

[0017] Figure 8 It is a schematic diagram of a system for determining the equivalent power of a supercapacitor according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0018] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0019] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0020] According to a first aspect of this embodiment, a method 100 for determining the equivalent power of a supercapacitor is provided. Figure 1 As shown, the method 100 includes:

[0021] S102: Under the DC voltage droop control, determine the steady-state point of the DC voltage and the target power disturbance magnitude, and determine the steady-state voltage point after the power disturbance according to the steady-state point of the DC voltage, the target power disturbance magnitude and the DC voltage droop coefficient;

[0022] S104: Determine the quantitative relationship between the supercapacitor voltage and the DC bus voltage according to the control of the supercapacitor;

[0023] S106: According to the energy conservation relationship, the energy released by the super capacitor before and after the power disturbance is equivalent to the equivalent capacitor on the DC bus;

[0024] S108: determining an equivalent capacitance according to the steady-state voltage point, the quantitative relationship, and the equivalent capacitor;

[0025] S110: Perform mathematical modeling based on the equivalent capacitance to obtain the equivalent power of the supercapacitor.

[0026] Specifically, the modeling method of the present invention is to be applied in a specific system structure. Figure 2 As shown, Figure 2 The DC microgrid structure shown is taken as an example to illustrate the modeling steps and effectiveness of the modeling method of this embodiment.

[0027] exist Figure 2 In the system, a supercapacitor system, a VSC that controls the DC voltage, and a power unit that simulates new energy or load disturbances are included. The power unit is simulated through a resistor and a DC-DC converter. The DC-DC converter controls the voltage on the resistor side to maintain a constant value and changes the power output by changing the resistor size. The control method of the VSC and the supercapacitor is as follows: Figure 3 and Figure 4 shown.

[0028] refer to Figure 3 As shown, u dc,set is the DC voltage reference value, u dc,pu is the per unit value of the DC bus voltage, Ps,pu is the per unit value of the active power injected into the DC microgrid by the VSC, and R d is the droop coefficient, k pu,s With k iu,s is the voltage loop proportional and integral coefficient, i td with i tq is the dq axis component of the sampling point current, L f With C fare the filter inductance and capacitance, θ pll is the phase-locking angle, P load,pu is the power per unit value of the power unit. Under the above control, the relationship between the power injected into the DC microgrid by the VSC and the DC voltage in the steady state satisfies:

[0029] u dc,pu =u dc,set -P s,pu R d =u dc,set -P load,pu R d (1)

[0030] Supercapacitor control methods such as Figure 4 As shown. sc is the supercapacitor voltage, U scB is the supercapacitor reference value, the inner loop control is voltage and current dual loop control, and current feedforward control is adopted, and the feedforward coefficient is F. In this control, U scB The relationship between the DC bus voltage is shown in formula (2):

[0031]

[0032] In formula (2), U rated is the rated voltage of the supercapacitor, u work is the voltage operating range, u sc,set is the supercapacitor voltage setting value, which can be taken as 1 / (1+Rd).

[0033] exist Figure 4 In the supercapacitor control shown, the supercapacitor voltage and the DC voltage satisfy:

[0034] u sc ≈U scB u dc,pu (3)

[0035] Combining equation (2) and equation (3), the relationship between the supercapacitor voltage and the DC voltage is:

[0036]

[0037] It can be seen from formula (4) that due to the nonlinear relationship between the supercapacitor and the DC bus voltage, although the linearization can describe the dynamic characteristics near small power disturbances, it is not applicable when the power disturbance is large. In order to more accurately describe the influence of the steady-state point and different power disturbances on the supercapacitor, the present invention proposes an equivalent capacitor C eq The concept is used to describe the impact of the supercapacitor system on the system. eq The physical meaning is the capacitance size corresponding to the energy released or absorbed by the supercapacitor before and after the disturbance when converted to the DC bus, such as Figure 5 shown.

[0038] According to the energy equality, we can get formula (5):

[0039]

[0040] In formula (5), u sc1 、u sc2 represents the steady-state voltage of the supercapacitor before and after the power disturbance. Similarly, u dc1 、u dc2 represents the steady-state voltage before and after the DC bus voltage disturbance. Combining equations (3), (4) and (5), we can get:

[0041] C eq =A T C sc (6)

[0042] Under the control of the above units, the conversion coefficient A T The specific expression is:

[0043]

[0044] According to equations (5) and (6), under large power disturbance, the transient support power dynamic characteristics of the supercapacitor under the above control method can be described as:

[0045]

[0046] The coefficient Ce q U 2 dcB / P B The equivalent inertia of the DC microgrid contributed by the supercapacitor power smoothing control is expressed as H sc .

[0047] In this way, under the modeling method of the present invention, the role of the supercapacitor system can be equivalent to the DC bus for system parameter and dynamic performance analysis. Then, by establishing the DC bus model and the VSC mathematical model, the mathematical model of the global system can be obtained. The mathematical models of each unit are as follows: Figure 6 shown.

[0048] Figure 6 In the above equation, the DC bus model is expressed as:

[0049]

[0050] C bus is the actual capacitance on the DC bus, the coefficient C bus U 2 dcB / P Bis the original inertia of the DC microgrid, expressed as H dc0 .

[0051] Figure 6 When the inner current loop is ignored, the dynamic characteristics of the active power increment injected into the DC microgrid by the balancing unit and the DC bus voltage change can be obtained as follows: udc (s) is the voltage loop PI control:

[0052]

[0053] Combining equation (8) and equation (9), the dynamic model of DC voltage can be obtained as follows:

[0054]

[0055] The specific expressions of the parameters in formula (11) are shown in formula (12):

[0056]

[0057] Built with PSCAD / EMPDC Figure 2 The simulation example shown verifies the supercapacitor control method of the present invention, and the control parameters of each unit are shown in Table 1.

[0058] Table 1 Basic system parameters

[0059]

[0060]

[0061] Simulation verification:

[0062] At the same time, under the same control of each unit, a linearized small signal model is established when the DC bus voltage is at the rated point, and the simulation results of the mathematical model, linearized small signal model and electromagnetic transient simulation model under the modeling method of the present invention under different working conditions are compared to verify the advantages of the modeling method of the present invention. The simulation results are as follows: Figure 7 shown.

[0063] When Csc=0.2F,uwork=0.5,Urated=0.2kV,Rd=0.05,PB=10kW,if a 5% small power disturbance is applied at the rated DC voltage point,at this time, according to formula (1), udc1,pu=udc2,pu=1,at this time, Ceq=0.2F,from Figure 7It can be seen from (a) that the mathematical model under the modeling method of the present invention and the conventional small signal model linearized for the steady-state point can both be consistent with the electromagnetic transient simulation model, indicating that they are accurate and applicable under small disturbances; however, when a 100% power step disturbance is applied, udc1,pu=1, udc2,pu=0.95 under this condition, and Ceq=0.16F at this time. Since the steady-state point does not change before the disturbance, the conventional linearized small signal model does not change, which can be obtained from Figure 7 As can be seen from (b), the mathematical model under the modeling method of the present invention is in better agreement with the electromagnetic transient simulation model, indicating that the mathematical model under the modeling method of the present invention is more accurate under high-power disturbances; when Csc = 5F, other parameters remain unchanged, under 100% power step disturbance, Ceq = 3.94F, as shown in FIG. Figure 7 (c) with Figure 7 Compared with (b), Ceq becomes larger and the DC voltage changes more smoothly. Figure 7 It can also be seen in (c) that at this time, the mathematical model under the modeling method of the present invention is more consistent with the simulation than the conventional linearization model, which reflects the correctness and advantages of the mathematical model under the modeling method of the present invention.

[0064] Therefore, according to the method for determining the equivalent power of the supercapacitor of this embodiment, regardless of whether the quantitative relationship between the supercapacitor voltage and the DC voltage is linear, the supercapacitor system can be equivalent to an equivalent capacitor on the DC bus, and the capacitance can be adjusted according to the disturbance value to be analyzed, so that the mathematical model can be applied to the analysis of small power disturbances. It can be applied to the dynamic performance analysis of the DC system by the supercapacitor system, and is suitable for analyzing both large power disturbances and small power disturbances, and has certain advantages over the conventional small signal linearization model that can only analyze small power disturbances.

[0065] Optionally, determining the steady-state voltage point after the power disturbance according to the steady-state point of the DC voltage, the target power disturbance magnitude, and the DC voltage droop coefficient includes: determining the steady-state voltage point after the power disturbance according to the following formula:

[0066] u dc2 =u dc1 +ΔP load R d

[0067] Among them, u dc1 with u dc2 are the steady-state points of the DC voltage before and after the disturbance, ΔP load is the target disturbance power to be analyzed, R d is the DC voltage droop coefficient.

[0068] Optionally, determining the quantitative relationship between the supercapacitor voltage and the DC bus voltage according to the control of the supercapacitor includes: determining the quantitative relationship between the supercapacitor voltage and the DC bus voltage according to the following formula:

[0069] u sc =f(u dc )

[0070] Among them, u sc is the supercapacitor voltage, u dc is the DC bus voltage.

[0071] Optionally, according to the energy conservation relationship, the energy released by the super capacitor before and after the power disturbance is equivalent to an equivalent capacitor on the DC bus, including: according to the following formula, the energy released by the super capacitor before and after the power disturbance is equivalent to an equivalent capacitor on the DC bus:

[0072]

[0073] Among them, C sc is the capacitance of the supercapacitor, C eq is the equivalent capacitance on the DC bus.

[0074] Optionally, determining the equivalent capacitance according to the steady-state voltage point, the quantitative relationship, and the equivalent capacitor includes: determining the equivalent capacitance according to the following formula:

[0075]

[0076] Among them, A T is the conversion coefficient between supercapacitor and equivalent capacitance.

[0077] Optionally, performing mathematical modeling according to the equivalent capacitance to obtain the equivalent power of the supercapacitor includes: obtaining an equivalent power expression of the supercapacitor according to a charging and discharging equation of the capacitor on the DC bus;

[0078] Determine the equivalent power of the supercapacitor using the following formula:

[0079]

[0080] Where ΔP sc，pu is the supercapacitor power per unit value, P B is the power reference value, U dcB is the rated value of DC voltage, Δu dc，pu is the per unit value of the DC voltage change.

[0081] According to another aspect of this embodiment, a system 800 for determining the equivalent power of a supercapacitor is also provided. Figure 8As shown, the system 800 includes: a steady-state voltage point determination module 810, which is used to determine the steady-state point of the DC voltage and the target power disturbance size under the DC voltage droop control, and determine the steady-state voltage point after the power disturbance according to the steady-state point of the DC voltage, the target power disturbance size and the DC voltage droop coefficient; a quantitative relationship determination module 820, which is used to determine the quantitative relationship between the supercapacitor voltage and the DC bus voltage according to the control of the supercapacitor; an equivalent capacitor determination module 830, which is used to equate the energy released before and after the supercapacitor power disturbance to the equivalent capacitor on the DC bus according to the energy conservation relationship; an equivalent capacitor determination module 840, which is used to determine the equivalent capacitance according to the steady-state voltage point, the quantitative relationship and the equivalent capacitor; and a supercapacitor equivalent power acquisition module 850, which is used to perform mathematical modeling according to the equivalent capacitance to obtain the supercapacitor equivalent power.

[0082] Optionally, the steady-state voltage point determination module 810 includes: a steady-state voltage point determination submodule, configured to determine the steady-state voltage point after the power disturbance according to the following formula:

[0083] u dc2 =u dc1 +ΔP load R d

[0084] Among them, u dc1 with u dc2 are the steady-state points of the DC voltage before and after the disturbance, ΔP load is the target disturbance power to be analyzed, R d is the DC voltage droop coefficient.

[0085] Optionally, the quantitative relationship determination module 820 includes: a quantitative relationship determination submodule, configured to determine the quantitative relationship between the supercapacitor voltage and the DC bus voltage according to the following formula:

[0086] u sc =f(u dc )

[0087] Among them, u sc is the supercapacitor voltage, u dc is the DC bus voltage.

[0088] Optionally, the determining equivalent capacitor module 830 includes: determining an equivalent capacitor submodule, which is used to convert the energy released by the super capacitor before and after the power disturbance to an equivalent capacitor on the DC bus according to the following formula:

[0089]

[0090] Among them, C scis the capacitance of the supercapacitor, C eq is the equivalent capacitance on the DC bus.

[0091] Optionally, the determining equivalent capacitance module 840 includes: determining an equivalent capacitance submodule, configured to determine the equivalent capacitance according to the following formula:

[0092]

[0093] Among them, A T is the conversion coefficient between supercapacitor and equivalent capacitance.

[0094] A system 800 for determining supercapacitor equivalent power according to an embodiment of the present invention corresponds to a method 100 for determining supercapacitor equivalent power according to another embodiment of the present invention, and will not be described in detail herein.

[0095] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0096] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0097] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1A function specified in one or more boxes.

[0098] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0099] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0100] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for determining the equivalent power of a supercapacitor, characterized in that: include: Under the DC voltage droop control, determine the steady-state point of the DC voltage and the target power disturbance magnitude, and determine the steady-state voltage point after the power disturbance according to the steady-state point of the DC voltage, the target power disturbance magnitude and the DC voltage droop coefficient; Determine the quantitative relationship between the supercapacitor voltage and the DC bus voltage based on the control of the supercapacitor; According to the energy conservation relationship, the energy released by the supercapacitor before and after the power disturbance is equivalent to the equivalent capacitor on the DC bus; Determining an equivalent capacitance according to the steady-state voltage point, the quantitative relationship, and the equivalent capacitor; Perform mathematical modeling based on the equivalent capacitance to obtain the equivalent power of the supercapacitor; The quantitative relationship between the supercapacitor voltage and the DC bus voltage is determined based on the control of the supercapacitor, including: According to the following formula, the quantitative relationship between the supercapacitor voltage and the DC bus voltage is determined: in sc =f(u dc ) Among them, u sc is the supercapacitor voltage, u dc is the DC bus voltage; Determining an equivalent capacitance according to the steady-state voltage point, the quantitative relationship, and the equivalent capacitor includes: Determine the equivalent capacitance using the following formula: Among them, A T is the conversion coefficient between supercapacitor and equivalent capacitance, C eq is the equivalent capacitance size on the DC bus; The relationship between supercapacitor voltage and DC voltage is: Among them, C sc is the capacitance of the supercapacitor, u dc1 with u dc2 are the steady-state points of the DC voltage before and after the disturbance, u dc,pu is the DC bus voltage per unit value, R d is the droop coefficient, U rated is the rated voltage of the supercapacitor, u work is the voltage working area; Conversion factor A T The specific expression is: Among them, U dcB is the DC voltage rating, U scB is the supercapacitor reference value, the inner loop control is voltage and current dual loop control, and current feedforward control is adopted, and the feedforward coefficient is F.

2. The method according to claim 1, characterized in that Determining a steady-state voltage point after power disturbance according to the steady-state point of the DC voltage, the target power disturbance magnitude, and the DC voltage droop coefficient includes: Determine the steady-state voltage point after the power disturbance according to the following formula: u dc2 =u dc1 +ΔP load R d Among them, u dc1 with u dc2 are the steady-state points of the DC voltage before and after the disturbance, ΔP load is the target disturbance power to be analyzed, R d is the DC voltage droop coefficient.

3. The method according to claim 1, characterized in that According to the energy conservation relationship, the energy released by the supercapacitor before and after the power disturbance is equivalent to the equivalent capacitor on the DC bus, including: According to the following formula, the energy released by the supercapacitor before and after the power disturbance is equivalent to the equivalent capacitor on the DC bus: Among them, C sc is the capacitance of the supercapacitor, C eq is the equivalent capacitance on the DC bus, u sc1 、u sc2 represents the steady-state voltage of the supercapacitor before and after the power disturbance, u dc1 with u dc2 are the steady-state points of the DC voltage before and after the disturbance, respectively.

4. The method according to claim 1, characterized in that: Mathematical modeling is performed based on the equivalent capacitance to obtain the equivalent power of the supercapacitor, including: According to the charging and discharging equations of the capacitor on the DC bus, the equivalent power expression of the supercapacitor is obtained; Determine the equivalent power of the supercapacitor using the following formula: Where ΔP sc，pu is the supercapacitor power per unit value, P B is the power reference value, U dcB is the rated value of DC voltage, Δu dc，pu is the per unit value of the DC voltage change, C eq is the equivalent capacitance on the DC bus.

5. A system for determining the equivalent power of a supercapacitor, characterized in that: include: A steady-state voltage point determination module is used to determine the steady-state point of the DC voltage and the target power disturbance magnitude under the DC voltage droop control, and determine the steady-state voltage point after the power disturbance according to the steady-state point of the DC voltage, the target power disturbance magnitude and the DC voltage droop coefficient; A quantitative relationship determination module is used to determine the quantitative relationship between the supercapacitor voltage and the DC bus voltage according to the control of the supercapacitor; An equivalent capacitor module is determined, which is used to convert the energy released by the super capacitor before and after the power disturbance into an equivalent capacitor on the DC bus according to the energy conservation relationship; An equivalent capacitance determination module is used to determine an equivalent capacitance according to the steady-state voltage point, the quantitative relationship and the equivalent capacitor; Obtaining a supercapacitor equivalent power module, which is used to perform mathematical modeling according to the equivalent capacitance to obtain the supercapacitor equivalent power; Determine the quantitative relationship module, including: The quantitative relationship determination submodule is used to determine the quantitative relationship between the supercapacitor voltage and the DC bus voltage according to the following formula: in sc =f(u dc ) Among them, u sc is the supercapacitor voltage, u dc is the DC bus voltage; Determine the equivalent capacitance module, including: The Determine Equivalent Capacitance submodule is used to determine the equivalent capacitance according to the following formula: Among them, A T is the conversion coefficient between supercapacitor and equivalent capacitance, C eq is the equivalent capacitance size on the DC bus; The relationship between supercapacitor voltage and DC voltage is: Among them, C sc is the capacitance of the supercapacitor, u dc1 with u dc2 are the steady-state points of the DC voltage before and after the disturbance, u dc,pu is the DC bus voltage per unit value, R d is the droop coefficient, U rated is the rated voltage of the supercapacitor, u work is the voltage working area; Conversion factor A T The specific expression is: Among them, U dcB is the DC voltage rating, U scB is the supercapacitor reference value, the inner loop control is voltage and current dual loop control, and current feedforward control is adopted, and the feedforward coefficient is F.

6. The system according to claim 5, characterized in that Determine the steady-state voltage point module, including: The steady-state voltage point determination submodule is used to determine the steady-state voltage point after the power disturbance according to the following formula: u dc2 =u dc1 +ΔP load R d Among them, u dc1 with u dc2 are the steady-state points of the DC voltage before and after the disturbance, ΔP load is the target disturbance power to be analyzed, R d is the DC voltage droop coefficient.

7. The system according to claim 5, characterized in that Determine the equivalent capacitor module, including: The equivalent capacitor determination submodule is used to convert the energy released by the supercapacitor before and after the power disturbance into the equivalent capacitor on the DC bus according to the following formula: Among them, C sc is the capacitance of the supercapacitor, C eq is the equivalent capacitance on the DC bus, u sc1 、u sc2 represents the steady-state voltage of the supercapacitor before and after the power disturbance, u dc1 with u dc2 are the steady-state points of the DC voltage before and after the disturbance, respectively.

8. The system according to claim 5, characterized in that Get the supercapacitor equivalent power module, including: A supercapacitor equivalent power submodule is obtained, which is used to obtain a supercapacitor equivalent power expression according to the charging and discharging equation of the capacitor on the DC bus; Determine the equivalent power of the supercapacitor using the following formula: Where ΔP sc，pu is the supercapacitor power per unit value, P B is the power reference value, U dcB is the rated value of DC voltage, Δu dc，pu is the per unit value of the DC voltage change, C eq is the equivalent capacitance on the DC bus.

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