Virtual rotor angle prediction method and device of grid-forming converter in fault scenario and storage medium

Abstract

The method comprises: determining a current coupling degree between each grid-forming converter and a reference grid-forming converter under each fault; fitting an unbalanced power model of each grid-forming converter according to coupling degree data and unbalanced power data of each grid-forming converter at each moment in a target period; determining a target unbalanced power of each grid-forming converter at a next moment according to the unbalanced power model of each grid-forming converter, a current unbalanced power and the current coupling degree; or determining the target unbalanced power of each grid-forming converter at the next moment according to the unbalanced power model of each grid-forming converter, the current unbalanced power and an interactive coupling degree. The method can quickly determine a virtual rotor angle of each grid-forming converter.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to the technical field of power systems, and particularly relate to a method and device for predicting virtual rotor angle of grid-forming converter under fault scenario and a storage medium. BACKGROUND

[0002] With the increasing installed capacity of new energy power generation equipment, the proportion of power converter interface power source in the power system is rapidly increasing, which brings great challenges to the analysis of power system stability. In addition, the traditional synchronous generator in the power system is gradually replaced by the power converter interface power source, and eventually forms a 100% converter interface power source power system (also known as a "full grid-forming converter interface power source power system"), which changes the dynamic characteristics of the power system, and thus the virtual rotor angle motion trend of the full grid-forming converter interface power source power system under fault scenario cannot be quickly judged. Therefore, the virtual rotor angle motion trend of each grid-forming converter under fault scenario cannot be predicted in advance, and thus the oscillation and out-of-step conditions that may occur in the power system under fault scenario cannot be suppressed. SUMMARY

[0003] Embodiments of the present disclosure provide a method and device for predicting virtual rotor angle of grid-forming converter under fault scenario and a storage medium, to quickly predict the virtual rotor angle motion trend of each grid-forming converter of the full grid-forming converter interface power source power system under fault scenario.

[0004] In a first aspect, embodiments of the present disclosure provide a method for predicting virtual rotor angle of grid-forming converter under fault scenario, applied to a full grid-forming converter interface power source power system. The method for predicting virtual rotor angle of grid-forming converter under fault scenario comprises:

[0005] determining a current coupling degree between each grid-forming converter and a reference grid-forming converter under each fault;

[0006] fitting an unbalanced power model of each grid-forming converter according to the coupling degree data and the unbalanced power data of each grid-forming converter at each time point in a target time period;

[0007] if the fault type is single fault, determining a target unbalanced power of each grid-forming converter at a next time point according to the unbalanced power model, the current unbalanced power and the current coupling degree of each grid-forming converter;

[0008] if the fault type is a cascading fault, determining a coupling weighting factor of each fault; determining an interaction coupling degree of each grid-forming converter according to the coupling weighting factor of each fault and a set of the current coupling degrees of each grid-forming converter under each fault; determining a target unbalanced power of each grid-forming converter at a next time according to the unbalanced power model, the current unbalanced power and the interaction coupling degree of each grid-forming converter;

[0009] determining a virtual rotor angle of each grid-forming converter according to the target unbalanced power and a target inertia of each grid-forming converter.

[0010] Optionally, the determining of the current coupling degree between each grid-forming converter and a reference grid-forming converter under each fault comprises:

[0011] determining a reference grid-forming converter according to an inertia and a current virtual rotor angular velocity of each grid-forming converter under each fault;

[0012] obtaining a current active power composition factor of each grid-forming converter and a standard active power composition factor of the reference grid-forming converter under each fault;

[0013] determining the current coupling degree of each grid-forming converter under each fault according to the current active power composition factor of each grid-forming converter and the standard active power composition factor of the reference grid-forming converter.

[0014] Optionally, the determining of the reference grid-forming converter according to the inertia and the current virtual rotor angular velocity of each grid-forming converter comprises:

[0015] determining a participation in overall dynamic behavior degree value of each grid-forming converter according to the inertia and the current virtual rotor angular velocity of each grid-forming converter;

[0016] screening the grid-forming converter with the largest overall dynamic behavior degree value as the reference grid-forming converter according to the participation in overall dynamic behavior degree value of each grid-forming converter.

[0017] Optionally, the current coupling degree of any grid-forming converter under a fault is:

[0018]

[0019] wherein t is a current time, C ij.t is a current coupling degree of the grid-forming converter j at the time t, E i is an internal electromotive force of the reference grid-forming converter i at the time t, E j(t) is the internal potential of grid-forming converter j at time t, Y ij (t) is the admittance between reference grid-forming converter i and grid-forming converter j at time t, δ i (t) is the virtual rotor angle of reference grid-forming converter i at time t, δ j (t) is the virtual rotor angle of grid-forming converter j at time t, θ ij (t) is the impedance angle between reference grid-forming converter i and grid-forming converter j at time t, θ ii (t) is the self-impedance angle of grid-forming converter i, i and j are both positive integers.

[0020] Optionally, if the fault type is single fault, determining the target unbalanced power of each grid-forming converter at the next time point comprises:

[0021] According to the unbalanced power model of each grid-forming converter, obtaining the proportional weight value of each grid-forming converter;

[0022] According to the current coupling degree of each grid-forming converter, determining the participation factor between each grid-forming converter and the remaining grid-forming converters;

[0023] According to the proportional weight value, current unbalanced power and participation factor of each grid-forming converter, determining the target unbalanced power of each grid-forming converter at the next time point.

[0024] Optionally, the target unbalanced power of grid-forming converter m at the next time point p m.t+1 is:

[0025] p m.t+1 = k0.p m.t +k1.(c 1m.t ×p 1.t )+k2.(c 2m.t ×p 2.t )+…+k n .(c nm.t ×p n.t );

[0026] Wherein, k0, k1, k2……k n is the proportional weight value of grid-forming converter m; t is the current time; p m.t is the unbalanced power of the mth grid-forming converter at time t; c 2m.t is the participation factor between the mth grid-forming converter and the first grid-forming converter at time t, c nm.t is the participation factor between the mth grid-forming converter and the second grid-forming converter at time t, …, cp is the participation factor between the m-th grid converter and the n-th grid converter at time t. 1.t Let p be the unbalanced power of the first grid-type converter at time t. 2.t Let p be the unbalanced power of the second grid-type converter at time t, ..., p n.t Let m be the unbalanced power of the nth grid-type converter at time t; m and n are both positive integers.

[0027] Optionally, the set C of the degree of interaction coupling of each of the grid-type converters t for:

[0028] C t =k1×C t.1 +k2×C t.2 +…+k n ×C t.n ;

[0029] C t = [C1, C2, ..., C n ];

[0030] Where k1 is the coupling weighting factor for the first fault, k2 is the coupling weighting factor for the second fault, ..., k n C is the coupling weighting factor for the nth fault; t.1 C is the set of current coupling levels for each of the grid-type converters under the first fault. t.2 For the set of current coupling levels of each of the grid-type converters under the second fault, ..., C t.n Let C1 be the set of current coupling degrees for each of the grid-type converters under the nth fault; C2 be the interaction coupling degree of the first grid-type converter, C2 be the interaction coupling degree of the second grid-type converter, ..., C n The degree of interactive coupling of the nth grid-type converter.

[0031] Optionally, if the fault type is a successive fault, determining the target unbalanced power of each of the grid-type converters at the next moment includes:

[0032] Based on the unbalanced power model of each grid-type converter, obtain the proportional weighting value of each grid-type converter;

[0033] Based on the degree of interaction coupling of each of the grid-type converters, calculate the interaction participation factor between each of the grid-type converters and the other grid-type converters;

[0034] The target unbalanced power of each grid converter at the next time step is calculated based on the proportional weighting value, the current unbalanced power, and the interaction participation factor of each grid converter.

[0035] Optionally, the target unbalanced power p of the grid-type converter e at the next moment... e.t+1 for:

[0036] p e.t+1 =k0.p e.t +k1.(c 1e.t ×p 1.t )+k2.(c 2e.t ×p 2.t )+…+k n .(c ne.t ×p n.t );

[0037] Where k0, k1, ..., k n The proportional weighting value of the grid-type converter e; t is the current time; p e.t Let c be the unbalanced power of the e-th grid-type converter at time t; 1e.t Let c be the interaction participation factor between the e-th grid converter and the first grid converter at time t. 2e.t Let c be the interaction participation factor between the e-th grid converter and the second grid converter at time t, ..., c ne.t p is the interaction participation factor between the e-th grid converter and the n-th grid converter at time t. 1.t Let p be the unbalanced power of the first grid-type converter at time t. 2.t Let p be the unbalanced power of the second grid-type converter at time t, ..., p n.t e represents the unbalanced power of the nth grid-type converter at time t; e and n are both positive integers, and n is the number of grid-type converters.

[0038] Optionally, determining the virtual rotor angle of each of the grid-type converters includes:

[0039] The angular acceleration of each grid-type converter is obtained based on the target unbalanced power and inertia of each grid-type converter.

[0040] The virtual rotor angle of each grid converter is obtained by integrating the angular acceleration of each grid converter.

[0041] In a second aspect, the present disclosure also provides a virtual rotor angle prediction device in a fault scenario, applied to a power system of a grid-forming converter interface power supply, the virtual rotor angle prediction device comprising:

[0042] a determination module configured to determine a current coupling degree between each of the grid-forming converters and a reference grid-forming converter in each fault;

[0043] a fitting module configured to fit an unbalanced power model of each of the grid-forming converters according to coupling degree data and unbalanced power data of each of the grid-forming converters at each time point in a target time period;

[0044] a single fault prediction module configured to, if the fault type is a single fault, determine a target unbalanced power of each of the grid-forming converters at a next time point according to the unbalanced power model, the current unbalanced power and the current coupling degree of each of the grid-forming converters;

[0045] a successive fault prediction module configured to, if the fault type is a successive fault, determine a coupling weighting factor of each fault, determine an interaction coupling degree of each of the grid-forming converters according to the coupling weighting factor of each fault and a set of the current coupling degrees of each of the grid-forming converters in each fault, and determine a target unbalanced power of each of the grid-forming converters at a next time point according to the unbalanced power model, the current unbalanced power and the interaction coupling degree of each of the grid-forming converters;

[0046] a virtual rotor angle calculation module configured to determine a virtual rotor angle of each of the grid-forming converters according to the target unbalanced power and a target inertia of each of the grid-forming converters.

[0047] In a third aspect, the present disclosure also provides a computer readable storage medium storing a computer program, the computer program being executed by a processor to implement the virtual rotor angle prediction method of the grid-forming converter in a fault scenario according to any of the embodiments of the present disclosure.

[0048] The embodiment of the present disclosure determines the current coupling degree of each grid-forming converter under each fault; according to the coupling degree data and the unbalanced power data of each grid-forming converter at each moment in the simulation period, the unbalanced power model of each grid-forming converter is fitted; if the fault type is single fault, the target unbalanced power of each grid-forming converter at the next moment is determined according to the unbalanced power model of each grid-forming converter, the current unbalanced power and the current coupling degree; if the fault type is successive fault, the coupling weighting factor of each fault is determined; the interaction coupling degree of each grid-forming converter is determined according to the coupling weighting factor of each fault and the set of the current coupling degree of each grid-forming converter under each fault; the target unbalanced power of each grid-forming converter at the next moment is determined according to the unbalanced power model of each grid-forming converter, the current unbalanced power and the interaction coupling degree; the virtual rotor angle of each grid-forming converter is determined according to the target unbalanced power and the target inertia of each grid-forming converter. Thus, the scheme can quickly predict the virtual rotor angle motion trend of the grid-forming converter interface power system under the fault scenario, so as to suppress the occurrence of oscillation and loss of step of the power system under the fault scenario. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0050] Figure 1 A flowchart of a virtual rotor angle prediction method of a grid-forming converter under a fault scenario provided by the embodiment of the present disclosure;

[0051] Figure 2 A flowchart of a step of determining the current coupling degree of each grid-forming converter under each fault provided by the embodiment of the present disclosure;

[0052] Figure 3 A flowchart of a step of determining the reference grid-forming converter provided by the embodiment of the present disclosure;

[0053] Figure 4 A flowchart of a step of determining the target unbalanced power of each grid-forming converter at the next moment in the case of single fault of the fault type provided by the embodiment of the present disclosure;

[0054] Figure 5 A flowchart of a step of determining the target unbalanced power of each grid-forming converter at the next moment in the case of successive fault of the fault type provided by the embodiment of the present disclosure;

[0055] Figure 6 A flowchart of a step of determining a virtual rotor angle of each grid-forming converter provided by the embodiment of the present disclosure is shown in the figure.

[0056] Figure 7 A structural diagram of a virtual rotor angle prediction device under a fault scenario provided by the embodiment of the present disclosure is shown in the figure. DETAILED DESCRIPTION

[0057] In order to enable those skilled in the art to better understand the present disclosure scheme, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below in combination with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present disclosure.

[0058] It should be noted that the terms "first", "second", and the like in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0059] Figure 1 A flowchart of a virtual rotor angle prediction method of a grid-forming converter under a fault scenario provided by the embodiment of the present disclosure is shown in the figure. The embodiment can be applicable to the prediction of the virtual rotor angle of each grid-forming converter of a full grid-forming converter interface power system including at least two grid-forming converters. The method can be performed by a virtual rotor angle prediction device under a fault scenario. The device can be realized in the form of hardware and / or software. The method specifically includes the following steps:

[0060] S110, determine the current coupling degree between each grid-forming converter and the reference grid-forming converter under each fault.

[0061] The grid-forming converter can realize power conversion of different voltage levels, different frequencies and different phases, and can actively participate in the construction and stability control of the power grid. The grid-forming converter participating in the operation of the power system to the greatest extent is the reference grid-forming converter. The coupling degree refers to the influence degree between each two grid-forming converters. Specifically, the coupling degree between two grid-forming converters is the ratio of the composition term of the related grid-forming converter to the reference term of another grid-forming converter in the electromagnetic power expression of the grid-forming converter. This step determines the current coupling degree between each grid-forming converter and the reference grid-forming converter in the entire grid-forming converter interface power system under each fault, that is, the participation degree of each grid-forming converter in the power system is obtained based on the reference grid-forming converter, so as to obtain the influence degree of each grid-forming converter on the power system, so as to accurately predict the change of each grid-forming converter at the next moment according to the influence degree of each grid-forming converter on the power system at the current moment.

[0062] In S120, the imbalance power model of each grid-forming converter is fitted according to the coupling degree data and the imbalance power data of each grid-forming converter at each time in the target time period.

[0063] The imbalance power is the difference between the mechanical power and the electromagnetic power. Since the mechanical power is constant by default, the change of the imbalance power essentially reflects the change of the electromagnetic power. The mechanical power and the electromagnetic power are parameters of the virtual synchronous generator technology adopted by the grid-forming converter. The mechanical power is equivalent to the active power instruction value, and the electromagnetic power is the active power output by the virtual synchronous generator (active power output value). The imbalance power = active power instruction value-active power output value. The imbalance power model is a formula with the highest fitting degree obtained by fitting the coupling degree data and the imbalance power data of each grid-forming converter at each time in the target time period.

[0064] Specifically, for each existing simulation time period, the coupling degree data and the imbalance power data of each grid-forming converter at each time in the existing simulation time period are statistically analyzed and summarized, and a function is constructed by means of fitting technology, which can represent a display expression formula of the correlation between the state quantity at the next moment and the state quantity at the previous moment in a short time period, so as to obtain the imbalance power model of each grid-forming converter.

[0065] In S130, if the fault type is single fault, the target imbalance power of each grid-forming converter at the next moment is determined according to the imbalance power model, the current imbalance power and the current coupling degree of each grid-forming converter.

[0066] Wherein, the single fault refers to the fault of the power system occurring at a single location and a single time period. The proportional weighting value of each grid-forming converter can be obtained according to the unbalanced power model of each grid-forming converter, that is, the proportionality coefficient of the current unbalanced power between each grid-forming converter and the coupling degree of the remaining grid-forming converters. The coupling degree between each grid-forming converter and the remaining grid-forming converters can be obtained according to the current coupling degree of each grid-forming converter, that is, the ratio of the current coupling degree of the grid-forming converter to be predicted to the current coupling degree of another grid-forming converter is the coupling degree between the two grid-forming converters. The current unbalanced power of each grid-forming converter can be the target unbalanced power determined at the last time or directly obtained. Thus, according to the proportional weighting value, the current unbalanced power and the coupling degree between each grid-forming converter and the remaining grid-forming converters, the target unbalanced power of each grid-forming converter at the next time is determined.

[0067] In S140, if the fault type is a successive fault, the coupling weighting factor of each fault is determined; the interactive coupling degree of each grid-forming converter is determined according to the coupling weighting factor of each fault and the set of the current coupling degree of each grid-forming converter under each fault; and the target unbalanced power of each grid-forming converter at the next time is determined according to the unbalanced power model of each grid-forming converter, the current unbalanced power and the interactive coupling degree.

[0068] Wherein, the successive fault refers to the fault of the power system occurring at multiple locations, a single time period or multiple time periods, that is, the fault occurring at multiple locations at the same time or the fault occurring at multiple locations at different times. The coupling weighting factor can be given according to the dominant mode of each fault constituting the successive fault (two-group mode division, that is, the division of the leading group and the remaining group) and the time difference of the successive fault (the time difference of the fault is the time interval between the two times of the successive fault. If the fault occurs at the same time, the time difference of the successive fault is 0). The coupling weighting factor represents the influence degree between each fault. For the successive fault scene, based on the coupling superposition idea, according to the coupling weighting factor of each fault and the set of the current coupling degree of each grid-forming converter under each fault, the interactive coupling ability of each grid-forming converter when multiple faults occur can be represented.

[0069] Specifically, the proportional weighting value of each grid-forming converter can be obtained according to the unbalanced power model of each grid-forming converter, that is, the proportionality coefficient of the current unbalanced power between each grid-forming converter and the remaining grid-forming converters in the coupling degree. The interactive coupling degree between each grid-forming converter and the remaining grid-forming converters in the successive fault can be obtained according to the coupling weighting factor of each fault and the current coupling degree of each grid-forming converter in each fault. The current unbalanced power of each grid-forming converter can be the target unbalanced power determined at the last moment or directly obtained. Thus, the target unbalanced power of each grid-forming converter at the next moment is determined according to the proportional weighting value of each grid-forming converter, the current unbalanced power and the interactive coupling degree between each grid-forming converter and the remaining grid-forming converters.

[0070] In S150, a virtual rotor angle of each grid-forming converter is determined according to the target unbalanced power and the target inertia of each grid-forming converter.

[0071] In S150, a virtual rotor angle of each grid-forming converter is determined according to the target unbalanced power and the target inertia of each grid-forming converter.

[0072] In the embodiments of the present disclosure, the current coupling degree of each grid-forming converter in each fault is determined. The unbalanced power model of each grid-forming converter is fitted according to the coupling degree data and the unbalanced power data of each grid-forming converter at each moment in the simulation period. If the fault type is single fault, the target unbalanced power of each grid-forming converter at the next moment is determined according to the unbalanced power model of each grid-forming converter, the current unbalanced power and the current coupling degree. If the fault type is successive fault, the coupling weighting factor of each fault is determined. The interactive coupling degree of each grid-forming converter is determined according to the coupling weighting factor of each fault and the set of the current coupling degree of each grid-forming converter in each fault. The target unbalanced power of each grid-forming converter at the next moment is determined according to the unbalanced power model of each grid-forming converter, the current unbalanced power and the interactive coupling degree. The virtual rotor angle of each grid-forming converter is determined according to the target unbalanced power and the target inertia of each grid-forming converter. Thus, the virtual rotor angle motion trend of the full grid-forming converter interface power system in the fault scenario can be quickly predicted, so as to suppress the occurrence of oscillation and loss of step of the power system in the fault scenario.

[0073] On the basis of the above-mentioned embodiments, optionally, Figure 2 A flow chart of a step of determining the current coupling degree of each grid-forming converter in each fault is provided for the embodiments of the present disclosure. As shown in FIG. 6, the current coupling degree of each grid-forming converter in each fault is determined according to the coupling degree data of each grid-forming converter in each fault.Figure 2 The step of determining the current coupling degree between each grid-forming converter and the reference grid-forming converter under each fault is described as follows:

[0074] S210, determining the reference grid-forming converter according to the inertia and the current virtual rotor angular velocity of each grid-forming converter under each fault.

[0075] The reference grid-forming converter is the grid-forming converter with the largest participation degree in the operation of the overall grid-forming converter interface power system, and the reference grid-forming converter is used as the standard to obtain the current participation degree of each grid-forming converter in the power system.

[0076] Specifically, the grid-forming converter with the largest participation degree in the overall dynamic behavior is defined as the reference grid-forming converter under each fault. Thus, the participation degree of each grid-forming converter in the overall dynamic behavior can be calculated according to the inertia and the current virtual rotor angular velocity of each grid-forming converter under each fault, so as to determine the grid-forming converter with the largest participation degree in the overall dynamic behavior.

[0077] S220, obtaining the current active power component factor of each grid-forming converter and the standard active power component factor of the reference grid-forming converter under each fault.

[0078] The current active power component factor (component term in the active power (electromagnetic power) expression) of each grid-forming converter and the standard active power component factor (component term in the active power (electromagnetic power) expression) of the reference grid-forming converter can be directly obtained. The current active power component factor of the grid-forming converter includes internal potential, admittance between the grid-forming converter and the reference grid-forming converter, virtual rotor angle, and impedance angle between the grid-forming converter and the reference grid-forming converter, etc. The standard active power component factor of the reference grid-forming converter includes internal potential, virtual rotor angle, and self-impedance angle, etc.

[0079] S230, determining the current coupling degree of each grid-forming converter under each fault according to the current active power component factor of each grid-forming converter and the standard active power component factor of the reference grid-forming converter under each fault.

[0080] Exemplarily, the current coupling degree of any grid-forming converter under a fault is:

[0081]

[0082] Wherein, t is the current time, C ij.t is the current coupling degree of the grid-forming converter j at time t, E i (t) is the internal potential of the reference grid-forming converter i at time t, E j (t) is the internal potential of the grid-forming converter j at time t, Yij (t) is the admittance angle between the reference grid-forming converter i and the grid-forming converter j at time t, δ i (t) is the virtual rotor angle of the reference grid-forming converter i at time t, δ j (t) is the virtual rotor angle of the grid-forming converter j at time t, θ ij (t) is the impedance angle between the reference grid-forming converter i and the grid-forming converter j at time t, θ ii (t) is the self-impedance angle of the grid-forming converter i, i and j are both positive integers.

[0083] On the basis of the above embodiment, optionally, Figure 3 is a flowchart of a step of determining a reference grid-forming converter provided by an embodiment of the present disclosure. As shown in the figure, Figure 3 a step of determining a reference grid-forming converter according to the inertia and the current virtual rotor angular velocity of each grid-forming converter is described:

[0084] S310, according to the inertia and the current virtual rotor angular velocity of each grid-forming converter, determining a participation degree value of each grid-forming converter in the overall dynamic behavior.

[0085] Specifically, the formula of the participation degree value in the overall dynamic behavior is:

[0086] wherein, J it is the inertia of the grid-forming converter i at time t, ω it is the virtual rotor angular velocity of the grid-forming converter i at time t.

[0087] S320, according to the participation degree value of each grid-forming converter in the overall dynamic behavior, screening the grid-forming converter with the largest overall dynamic behavior degree value as the reference grid-forming converter.

[0088] On the basis of the above embodiment, optionally, Figure 4 is a flowchart of a step of determining a target unbalanced power of each grid-forming converter at the next moment in the case of a single fault type provided by an embodiment of the present disclosure. As shown in the figure, Figure 4 a step of determining a target unbalanced power of each grid-forming converter at the next moment in the case of a single fault type is described:

[0089] S410, according to the unbalanced power model of each grid-forming converter, obtaining a proportional weight value of each grid-forming converter.

[0090] Wherein, the proportional weight value represents the proportionality coefficient of the current unbalanced power under the coupling degree between each grid-forming converter and the remaining grid-forming converters.

[0091] S420, determining a participation factor between each grid-forming converter and the rest of the grid-forming converters according to the current coupling degree of each grid-forming converter.

[0092] Exemplarily, the ratio of the current coupling degree of the grid-forming converter to be predicted to the current coupling degree of another grid-forming converter is the participation factor between the two grid-forming converters, i.e., the coupling degree between each grid-forming converter and the rest of the grid-forming converters, so that the participation factor is not measured between any two grid-forming converters based on the grid-forming converter with the largest "screening overall dynamic behavior degree value" as the reference grid-forming converter.

[0093] S430, determining the target unbalanced power of each grid-forming converter at the next moment according to the proportional weighting value of each grid-forming converter, the current unbalanced power and the participation factor.

[0094] Specifically, the target unbalanced power p m.t+1 of the grid-forming converter m at the next moment is:

[0095] p m.t+1 = k0.p m.t + k1.(c 1m.t × p 1.t ) + k2.(c 2m.t × p 2.t ) + … + k n .(c nm.t × p n.t );

[0096] wherein k0, k1, k2, …, k n are the proportional weighting values of the grid-forming converter m; t is the current moment; p m.t is the unbalanced power of the mth grid-forming converter at the tth moment; c 1m.t is the participation factor between the mth grid-forming converter and the 1st grid-forming converter at the tth moment, c 2m.t is the participation factor between the mth grid-forming converter and the 2nd grid-forming converter at the tth moment, …, c nm.t is the participation factor between the mth grid-forming converter and the nth grid-forming converter at the tth moment; p 1.t is the unbalanced power of the 1st grid-forming converter at the tth moment, p 2.t is the unbalanced power of the 2nd grid-forming converter at the tth moment, …, p n.t is the unbalanced power of the nth grid-forming converter at the tth moment; m and n are both positive integers.

[0097] On the basis of the above embodiment, optionally, the set C t of the interaction coupling degrees of each grid-forming converter is:

[0098] C t =k1×C t.1 +k2×C t.2 +…+k n ×C t.n ;

[0099] C t = [C1, C2, ..., C n ];

[0100] Where k1 is the coupling weighting factor for the first fault, k2 is the coupling weighting factor for the second fault, ..., k n C is the coupling weighting factor for the nth fault; t.1 C represents the set of current coupling levels for each grid-type converter under the first fault. t.2 Let C be the set of current coupling levels of each grid-type converter under the second fault, ..., C t.n Let C1 be the set of current coupling levels of each grid-type converter under the nth fault; C2 is the interaction coupling level of the first grid-type converter, C2 is the interaction coupling level of the second grid-type converter, ..., C n The degree of interaction coupling of the nth grid-type converter.

[0101] Based on the above embodiments, optionally, Figure 5 This is a flowchart illustrating the steps for determining the target unbalanced power of each grid-type converter at the next moment in the case of a successive fault, as provided in an embodiment of this disclosure. Figure 5 As shown, the steps for determining the target unbalanced power of each grid-type converter at the next moment are explained if the fault type is a successive fault:

[0102] S510. Based on the unbalanced power model of each grid-type converter, obtain the proportional weighting value of each grid-type converter.

[0103] The proportional weighting value represents the weighting factor of the current unbalanced power under the degree of coupling between each grid-type converter and the other grid-type converters.

[0104] S520. Based on the degree of interaction coupling of each grid-type converter, calculate the interaction participation factor between each grid-type converter and the other grid-type converters.

[0105] For example, under successive faults, the ratio of the interaction coupling degree of the grid converter to be predicted to the interaction coupling degree of another grid converter is the interaction participation factor between the two grid converters.

[0106] S530, calculating the target unbalanced power of each grid-forming converter at the next moment according to the proportional weight value of each grid-forming converter, the current unbalanced power and the interaction participation factor.

[0107] Exemplarily, the target unbalanced power pe of the grid-forming converter e at the next moment is: e.t+1

[0108] e.t+1 = k0.p e.t + k1.(c 1e.t × p 1.t ) + k2.(c 2e.t × p 2.t ) + … + k n .(c ne.t × p n.t ).

[0109] Wherein, k0, k1, … k n are the proportional weight values of the grid-forming converter e; t is the current moment; p e.t is the unbalanced power of the e-th grid-forming converter at the t moment; c 1e.t is the interaction participation factor between the e-th grid-forming converter and the first grid-forming converter at the t moment, c 2e.t is the interaction participation factor between the e-th grid-forming converter and the second grid-forming converter at the t moment, …, c ne.t is the interaction participation factor between the e-th grid-forming converter and the n-th grid-forming converter at the t moment; p 1.t is the unbalanced power of the first grid-forming converter at the t moment, p 2.t is the unbalanced power of the second grid-forming converter at the t moment, …, p n.t is the unbalanced power of the n-th grid-forming converter at the t moment; e and n are both positive integers, and n is the number of grid-forming converters.

[0110] On the basis of the above embodiment, optionally, Figure 6 is a flowchart of the steps of determining the virtual rotor angle of each grid-forming converter provided by the embodiment of the present disclosure. As Figure 6 shown, the steps of determining the virtual rotor angle of each grid-forming converter are described as follows:

[0111] S610, obtaining the angular acceleration of each grid-forming converter according to the target unbalanced power and the inertia of each grid-forming converter.

[0112] S620, integrating the angular acceleration of each grid-forming converter to obtain the virtual rotor angle of each grid-forming converter.

[0113] ​​Figure 7 A structural schematic diagram of a virtual rotor angle prediction device under a fault scenario is provided for an embodiment of the present disclosure. The virtual rotor angle prediction device under the fault scenario is applied to a full meshed converter interfaced power system, and comprises:

[0114] A determination module 110 is configured to determine a current coupling degree between each meshed converter and a reference meshed converter under each fault;

[0115] A fitting module 120 is configured to fit an unbalanced power model of each meshed converter according to coupling degree data and unbalanced power data of each meshed converter at each time point in a target time period;

[0116] A single fault prediction module 130 is configured to determine a target unbalanced power of each meshed converter at a next time point according to the unbalanced power model of each meshed converter, a current unbalanced power and the current coupling degree if the fault type is a single fault;

[0117] A successive fault prediction module 140 is configured to determine a coupling weighting factor of each fault if the fault type is a successive fault; determine an interactive coupling degree of each meshed converter according to the coupling weighting factor of each fault and a set of the current coupling degree of each meshed converter under each fault; and determine a target unbalanced power of each meshed converter at a next time point according to the unbalanced power model of each meshed converter, a current unbalanced power and the interactive coupling degree;

[0118] A virtual rotor angle calculation module 150 is configured to determine a virtual rotor angle of each meshed converter according to the target unbalanced power and a target inertia of each meshed converter.

[0119] The embodiment of the present disclosure determines the current coupling degree of each network-forming type converter under each fault through the determination module 110; the fitting module 120 fits to obtain the unbalanced power model of each network-forming type converter according to the coupling degree data and the unbalanced power data of each network-forming type converter at each moment in the simulation period; the single fault prediction module 130 is used for determining the target unbalanced power of each network-forming type converter at the next moment according to the unbalanced power model, the current unbalanced power and the current coupling degree of each network-forming type converter if the fault type is single fault; the successive fault prediction module 140 is used for determining the coupling weighting factor of each fault if the fault type is successive fault; determining the interaction coupling degree of each network-forming type converter according to the coupling weighting factor of each fault and the set of the current coupling degree of each network-forming type converter under each fault; determining the target unbalanced power of each network-forming type converter at the next moment according to the unbalanced power model, the current unbalanced power and the interaction coupling degree of each network-forming type converter; the virtual rotor angle calculation module 150 determines the virtual rotor angle of each network-forming type converter according to the target unbalanced power and the target inertia of each network-forming type converter. Thus, the scheme can quickly predict the virtual rotor angle motion trend of the full network-forming type converter interface power system under the fault scenario, so as to suppress the occurrence of oscillation and loss of step of the power system under the fault scenario.

[0120] On the basis of the above-mentioned embodiment, optionally, the determination module comprises:

[0121] The reference network-forming type converter determination unit is configured to determine the reference network-forming type converter according to the inertia and the current virtual rotor angular velocity of each network-forming type converter under each fault.

[0122] The active power component acquisition unit is configured to acquire the current active power component of each network-forming type converter and the standard active power component of the reference network-forming type converter under each fault.

[0123] The current coupling degree calculation unit is configured to determine the current coupling degree of each network-forming type converter under each fault according to the current active power component of each network-forming type converter and the standard active power component of the reference network-forming type converter.

[0124] On the basis of the above-mentioned embodiment, optionally, the reference network-forming type converter determination unit is specifically configured to:

[0125] determine the participation degree value of the overall dynamic behavior of each network-forming type converter according to the inertia and the current virtual rotor angular velocity of each network-forming type converter.

[0126] According to the degree of participation of each grid-forming converter in the overall dynamic behavior, a grid-forming converter with the largest overall dynamic behavior degree value is screened as a reference grid-forming converter.

[0127] On the basis of the above-mentioned embodiments, optionally, the single-fault prediction module comprises:

[0128] The first proportionally weighted value determination unit is configured to obtain a proportionally weighted value of each grid-forming converter according to an unbalanced power model of each grid-forming converter.

[0129] The participation factor determination unit is configured to determine a participation factor between each grid-forming converter and the remaining grid-forming converters according to a current coupling degree of each grid-forming converter.

[0130] The first target unbalanced power calculation unit is configured to determine a target unbalanced power of each grid-forming converter at a next time according to the proportionally weighted value, the current unbalanced power and the participation factor of each grid-forming converter.

[0131] On the basis of the above-mentioned embodiments, optionally, the successive-fault prediction module comprises:

[0132] The second proportionally weighted value determination unit is configured to obtain a proportionally weighted value of each grid-forming converter according to an unbalanced power model of each grid-forming converter.

[0133] The interactive participation factor determination unit is configured to calculate an interactive participation factor between each grid-forming converter and the remaining grid-forming converters according to an interactive coupling degree of each grid-forming converter.

[0134] The second target unbalanced power calculation unit is configured to calculate a target unbalanced power of each grid-forming converter at a next time according to the proportionally weighted value, the current unbalanced power and the interactive participation factor of each grid-forming converter.

[0135] On the basis of the above-mentioned embodiments, optionally, the virtual rotor angle calculation module comprises:

[0136] The acceleration calculation unit is configured to obtain an angular acceleration of each grid-forming converter according to the target unbalanced power and the inertia of each grid-forming converter.

[0137] The virtual rotor angle calculation unit is configured to integrate the angular acceleration of each grid-forming converter to obtain a virtual rotor angle of each grid-forming converter.

[0138] The disclosure also provides a computer readable storage medium, and the computer readable storage medium stores a computer program. When the computer program is executed by a processor, the virtual rotor angle prediction method of the grid-forming converter in the fault scenario is realized.

[0139] The computer storage medium of the embodiments of the present disclosure can adopt any combination of one or more computer readable media. The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium may, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or apparatus, or any combination thereof. The computer readable storage medium includes, but is not limited to, a non-exhaustive list: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an electrically erasable, programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present disclosure, the computer readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device or apparatus.

[0140] The computer readable signal medium can include a data signal propagating in a baseband or as part of a carrier wave propagating through a transmission medium, and the data signal bears computer readable program code. Such a propagating data signal can take many forms, including but not limited to electro-magnetic, optical, or any suitable combination thereof. The computer readable signal medium can also be any computer readable medium that is not a computer readable storage medium and that can be used to carry or store a program for use by or in connection with an instruction execution system, device or apparatus.

[0141] The program code contained on the computer readable medium can be transmitted in any suitable medium, including but not limited to wireless, wire, optical cable, radio frequency (RF), etc., or any suitable combination thereof.

[0142] Computer program code for carrying out operations of the present disclosure can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++, Ruby, Go, or the like, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0143] Those skilled in the art will appreciate that the term user terminal encompasses any appropriate type of wireless user equipment, such as a mobile phone, a portable data processing apparatus, a portable web browser, or a vehicle mounted mobile station.

[0144] In general, the various embodiments of the present disclosure can be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects can be implemented in hardware, while other aspects can be implemented in

[0145] Embodiments of the present disclosure can be implemented by the data processor of a mobile device executing computer program instructions, for example in a processor entity, or by hardware, or by a combination of software and hardware. Computer program instructions can be in assemblies, Instruction Set Architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state setting data, or in any combination of one or more programming languages, written in any combination of one or more programming languages, as source code, as object code, or both.

[0146] Any block diagram of logical flow in the accompanying drawings of this disclosure may represent program steps, or may represent interconnected logic circuits, modules, and functions, or may represent a combination of program steps and logic circuits, modules, and functions. The computer program may be stored in memory. The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as, but not limited to, read-only memory (ROM), random access memory (RAM), optical storage devices and systems (Digital Multifunction Discs, DVDs, or CDs), etc. Computer-readable media may include non-transitory storage media. The data processor may be of any type suitable to the local technical environment, such as, but not limited to, general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), and processors based on multi-core processor architectures.

[0147] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.

[0148] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A method for predicting the virtual rotor angle of a grid-connected converter under fault scenarios, applied to a fully grid-connected converter interface power system, wherein the system includes at least two grid-connected converters, characterized in that... include: Determine the current coupling level between each of the grid-type converters and the reference grid-type converter under each fault condition; Based on the coupling degree data and unbalanced power data of each grid-type converter at each moment in the target time period, the unbalanced power model of each grid-type converter is fitted to obtain the model. If the fault type is a single fault, then the target unbalanced power of each grid-type converter at the next moment is determined based on the unbalanced power model, the current unbalanced power, and the current coupling degree of each grid-type converter. If the fault type is a successive fault, then determine the coupling weighting factor for each fault; Based on the set of coupling weighting factors for each fault and the current coupling degree of each grid converter under each fault, the interaction coupling degree of each grid converter is determined; based on the unbalanced power model of each grid converter, the current unbalanced power, and the interaction coupling degree, the target unbalanced power of each grid converter at the next moment is determined. The virtual rotor angle of each grid-type converter is determined based on the target unbalanced power and target inertia of each grid-type converter.

2. The virtual rotor angle prediction method for grid-type converters under fault scenarios according to claim 1, characterized in that, Determining the current coupling level between each of the grid-type converters and the reference grid-type converter under each fault includes: Under each fault condition, a reference grid converter is determined based on the inertia of each grid converter and the current virtual rotor angular velocity. Obtain the current active power composition factors of each grid-type converter under each fault and the standard active power composition factors of the reference grid-type converter; Based on the current active power composition factors of each grid converter under each fault and the standard active power composition factors of the reference grid converter, the current coupling degree of each grid converter under each fault is determined.

3. The virtual rotor angle prediction method for grid-type converters under fault scenarios according to claim 2, characterized in that, The process of determining the reference grid converter based on the inertia and current virtual rotor angular velocity of each grid converter includes: Based on the inertia of each grid-type converter and the current virtual rotor angular velocity, determine the degree of participation of each grid-type converter in the overall dynamic behavior; Based on the participation level value of each grid-type converter in the overall dynamic behavior, the grid-type converter with the largest overall dynamic behavior value is selected as the benchmark grid-type converter.

4. The virtual rotor angle prediction method for grid-type converters under fault scenarios according to claim 3, characterized in that, The current coupling level of any of the grid-type converters under a fault condition is: Where t is the current time, C ij.t Let E be the current coupling level of the grid-type converter j at time t. i (t) represents the internal potential of the reference grid-type converter i at time t, E j (t) represents the internal potential of grid-connected converter j at time t, Y ij (t) represents the admittance between the reference grid-type converter i and the grid-type converter j at time t, δ i (t) represents the virtual rotor angle of the reference grid-type converter i at time t, δ j (t) represents the virtual rotor angle of the grid-type converter j at time t, θ ij (t) represents the impedance angle between the reference grid converter i and the grid converter j at time t, θ ii (t) represents the self-impedance angle of grid-type converter i, where i and j are both positive integers.

5. The virtual rotor angle prediction method for grid-type converters under fault scenarios according to claim 1, characterized in that, If the fault type is a single fault, determine the target unbalanced power of each of the grid-type converters at the next time step, including: Based on the unbalanced power model of each grid-type converter, obtain the proportional weighting value of each grid-type converter; Based on the current coupling degree of each of the grid converters, the participation factor between each of the grid converters and the other grid converters is determined; The target unbalanced power of each grid converter at the next time step is determined based on the proportional weighting value, the current unbalanced power, and the participation factor for each grid converter.

6. The virtual rotor angle prediction method for grid-type converters under fault scenarios according to claim 5, characterized in that, The target unbalanced power p of the grid-type converter m at the next moment. m.t+1 for: p m.t+1 =k0.p m.t +k1.(c 1m.t ×p 1.t )+k2.(c 2m.t ×p 2.t )+…+k n .(c nm.t ×p n.t ); Where k0, k1, k2...k n The proportional weighting value of grid-connected converter m; t is the current time; p m.t Let c be the unbalanced power of the m-th grid-type converter at time t; 1m.t Let c be the participation factor between the m-th grid converter and the 1-th grid converter at time t. 2m.t Let c be the participation factor between the m-th grid converter and the second grid converter at time t, ..., c nm.t p is the participation factor between the m-th grid converter and the n-th grid converter at time t. 1.t Let p be the unbalanced power of the first grid-type converter at time t. 1.t Let p be the unbalanced power of the second grid-type converter at time t, ..., p n.t Let m be the unbalanced power of the nth grid-type converter at time t; m and n are both positive integers.

7. The virtual rotor angle prediction method for grid-type converters under fault scenarios according to claim 1, characterized in that, The set C of the degree of interaction coupling of each of the grid-type converters t for: C t =k1×C t.1 +k2×C t.2 +…+k n ×C t.n ; C t =[C1,C2,…,C n ]; Where k1 is the coupling weighting factor for the first fault, k2 is the coupling weighting factor for the second fault, ..., k n C is the coupling weighting factor for the nth fault; t.1 C is the set of current coupling levels for each of the grid-type converters under the first fault. t.2 For the set of current coupling levels of each of the grid-type converters under the second fault, ..., C t.n Let C1 be the set of current coupling degrees for each of the grid-type converters under the nth fault; C2 be the interaction coupling degree of the first grid-type converter, C2 be the interaction coupling degree of the second grid-type converter, ..., C n The degree of interactive coupling of the nth grid-type converter.

8. The virtual rotor angle prediction method for grid-type converters under fault scenarios according to claim 7, characterized in that, If the fault type is a successive fault, determine the target unbalanced power of each of the grid-type converters at the next moment, including: Based on the unbalanced power model of each grid-type converter, obtain the proportional weighting value of each grid-type converter; Based on the degree of interaction coupling of each of the grid-type converters, calculate the interaction participation factor between each of the grid-type converters and the other grid-type converters; The target unbalanced power of each grid converter at the next time step is calculated based on the proportional weighting value, the current unbalanced power, and the interaction participation factor of each grid converter.

9. The virtual rotor angle prediction method for grid-type converters under fault scenarios according to claim 8, characterized in that, The target unbalanced power p of the grid-type converter e at the next moment. e.t+1 for: p e.t+1 =k0.p e.t +k1.(c 1e.t ×p 1.t )+k2.(c 2e.t ×p 2.t )+…+k n .(c ne.t ×p n.t ); Where k0, k1, ... k n The proportional weighting value of the grid-type converter e; t is the current time; p e.t Let c be the unbalanced power of the e-th grid-type converter at time t; 1e.t Let c be the interaction participation factor between the e-th grid converter and the first grid converter at time t. 2e.t Let c be the interaction participation factor between the e-th grid converter and the second grid converter at time t, ..., c ne.t p is the interaction participation factor between the e-th grid converter and the n-th grid converter at time t. 1.t Let p be the unbalanced power of the first grid-type converter at time t. 2.t Let p be the unbalanced power of the second grid-type converter at time t, ..., p n.t e represents the unbalanced power of the nth grid-type converter at time t; e and n are both positive integers, and n is the number of grid-type converters.

10. The virtual rotor angle prediction method for grid-type converters under fault scenarios according to claim 1, characterized in that, Determining the virtual rotor angle of each of the grid-type converters includes: The angular acceleration of each grid-type converter is obtained based on the target unbalanced power and inertia of each grid-type converter. The virtual rotor angle of each grid converter is obtained by integrating the angular acceleration of each grid converter.

11. A virtual rotor angle prediction device under fault scenarios, applied to a fully grid-type converter interface power system, characterized in that, include: The determination module is used to determine the current coupling degree between each of the grid-type converters and the reference grid-type converter under each fault condition; The fitting module is used to fit and obtain the unbalanced power model of each grid-type converter based on the coupling degree data and unbalanced power data of each grid-type converter at each moment of the target time period. The single fault prediction module is used to determine the target unbalanced power of each grid-type converter at the next moment if the fault type is a single fault, based on the unbalanced power model, the current unbalanced power, and the current coupling degree of each grid-type converter. The successive fault prediction module is used to determine the coupling weighting factor for each fault if the fault type is a successive fault. Based on the set of coupling weighting factors for each fault and the current coupling degree of each grid converter under each fault, the interaction coupling degree of each grid converter is determined; based on the unbalanced power model of each grid converter, the current unbalanced power, and the interaction coupling degree, the target unbalanced power of each grid converter at the next moment is determined. The virtual rotor angle calculation module is used to determine the virtual rotor angle of each grid-type converter based on the target unbalanced power and target inertia of each grid-type converter.

12. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the virtual rotor angle prediction method for grid-type converters under fault scenarios as described in any of claims 1-10.

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