Virtual rotor angle prediction method and device of network-forming converter in fault scene, and storage medium

Abstract

The embodiment of the invention discloses a virtual rotor angle prediction method and device for a network-forming converter in a fault scene and a storage medium. The prediction method comprises the following steps: determining the current coupling degree between each network construction type converter and a reference network construction type converter under each fault; according to the coupling degree data and the unbalanced power data of each grid-forming converter at each moment of the target time period, fitting to obtain an unbalanced power model of each grid-forming converter; according to the unbalanced power model of each network construction type converter, the current unbalanced power and the current coupling degree, determining the target unbalanced power of each network construction type converter at the next moment; or according to the unbalanced power model of each network construction type converter, the current unbalanced power and the interactive coupling degree, determining the target unbalanced power of each network construction type converter at the next moment. According to the scheme, the virtual rotor angle of each grid-forming converter can be quickly determined.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of power systems, and in particular to a method, device, and storage medium for predicting a virtual rotor angle of a grid-connected converter under a fault scenario. Background Art

[0002] With the continuous increase in the installed capacity of new energy power generation equipment, the proportion of power converter interface power supply in the power system has increased sharply, which makes the analysis of power system stability face huge challenges. In addition, the traditional synchronous machine power supply in the power system is gradually replaced by the power converter interface power supply, and finally forms a 100% converter interface power supply power system (also called "full grid-type converter interface power supply power system"), which will cause the dynamic characteristics of the power system to change essentially, resulting in the virtual rotor angle movement trend of the full grid-type converter interface power supply power system in the fault scenario cannot be quickly judged, and thus it is impossible to predict the virtual rotor angle movement trend of each grid-type converter in advance, so as to suppress the oscillation and loss of step that may occur in the power system in the fault scenario. Summary of the invention

[0003] The embodiments of the present disclosure provide a method, device and storage medium for predicting the virtual rotor angle of a grid-type converter under a fault scenario, so as to quickly predict the movement trend of the virtual rotor angle of each grid-type converter of a power supply system interfaced with a full grid-type converter under a fault scenario.

[0004] In a first aspect, an embodiment of the present disclosure provides a method for predicting a virtual rotor angle of a grid-type converter under a fault scenario, which is applied to a full grid-type converter interface power supply power system. The method for predicting a virtual rotor angle of a grid-type converter under a fault scenario includes:

[0005] Determining a current degree of coupling between each of the grid-connected converters and a reference grid-connected converter for each fault;

[0006] According to the coupling degree data and unbalanced power data of each of the grid-type converters at each moment in the target period, fitting and obtaining an unbalanced power model of each of the grid-type converters;

[0007] If the fault type is a single fault, determining the target unbalanced power of each of the grid-type converters at the next moment according to the unbalanced power model, the current unbalanced power and the current coupling degree of each of the grid-type converters;

[0008] If the fault type is a sequential fault, determine the coupling weighting factor of each fault; determine the mutual coupling degree of each grid-type converter according to the coupling weighting factor of each fault and the set of the current coupling degree of each grid-type converter under each fault; determine the target unbalanced power of each grid-type converter at the next moment according to the unbalanced power model, the current unbalanced power and the mutual coupling degree of each grid-type converter;

[0009] A virtual rotor angle of each of the grid-type converters is determined according to the target unbalanced power and the target inertia of each of the grid-type converters.

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

[0011] Under each fault, a reference grid-type converter is determined according to the inertia of each grid-type converter and the current virtual rotor angular velocity;

[0012] Obtaining the current active power component factor of each grid-type converter and the standard active power component factor of the reference grid-type converter under each fault;

[0013] According to the current active power component factor of each grid-type converter under each fault and the standard active power component factor of the reference grid-type converter, the current coupling degree of each grid-type converter under each fault is determined.

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

[0015] Determining the degree of participation of each of the grid-type converters in the overall dynamic behavior according to the inertia of each of the grid-type converters and the current virtual rotor angular velocity;

[0016] According to the participation degree value of each of the grid-type converters in the overall dynamic behavior, the grid-type converter with the largest overall dynamic behavior degree value is selected as the reference grid-type converter.

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

[0018]

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

[0020] Optionally, if the fault type is a single fault, determining a target unbalanced power of each of the grid-connected converters at the next moment includes:

[0021] According to the unbalanced power model of each of the grid-type converters, obtaining a proportional weighted value of each of the grid-type converters;

[0022] Determining a participation factor between each of the grid-type converters and the remaining grid-type converters according to a current coupling degree of each of the grid-type converters;

[0023] The target unbalanced power of each of the grid-type converters at the next moment is determined according to the proportional weighted value, the current unbalanced power and the participation factor of each of the grid-type converters.

[0024] Optionally, the target unbalanced power p of the grid-connected converter i at the next moment is i.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 );

[0025] Among them, k0, k1, k2...k n is the proportional weighted value of the grid-type converter m; t is the current moment; p m.t is the unbalanced power of the mth grid-type converter at time t; is the participation factor between the mth grid-type converter and the first grid-type converter at time t, c 2m.t is the participation factor between the mth grid-connected converter and the second grid-connected converter at time t, ..., c nm.t is the participation factor between the mth grid-type converter and the nth grid-type converter at time t; p1.t is the unbalanced power of the first grid-connected converter at time t, p 2.t is the unbalanced power of the second grid-connected converter at time t, ..., p n.t is the unbalanced power of the nth grid-connected converter at time t; m and n are both positive integers.

[0026] Optionally, the set C of the mutual coupling degree of each grid-connected converter is t for:

[0027] C t =k1×C t.1 +k2×C t.2 +…+k l ×C t.l ;

[0028] C t =[C1, C2, ..., C n ];

[0029] Where k1 is the coupling weighting factor of the first fault, k2 is the coupling weighting factor of the second fault, ..., k l is the coupling weighting factor of the first fault; C t.1 is the set of the current coupling degrees of each grid-connected converter under the first fault, C t.2 is the set of the current coupling degrees of each grid-connected converter under the second fault, ..., C t.l is the set of the current coupling degrees of each of the grid-type converters under the lth fault; C1 is the mutual coupling degree of the first grid-type converter, C2 is the mutual coupling degree of the second grid-type converter, ..., C n is the interactive coupling degree of the nth grid-connected converter.

[0030] Optionally, if the fault type is a sequential fault, determining a target unbalanced power of each of the grid-connected converters at the next moment includes:

[0031] According to the unbalanced power model of each of the grid-type converters, obtaining a proportional weighted value of each of the grid-type converters;

[0032] Calculating the interaction participation factor between each of the grid-type converters and the remaining grid-type converters according to the interaction coupling degree of each of the grid-type converters;

[0033] The target unbalanced power of each of the grid-type converters at the next moment is calculated according to the proportional weighted value, the current unbalanced power and the interaction participation factor of each of the grid-type converters.

[0034] Optionally, the target unbalanced power p of the grid-connected converter e at the next moment is 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 );

[0035] Among them, k0, k1, ... k n is the proportional weighted value of the grid-type converter e; t is the current moment; p e.t is the unbalanced power of the e-th grid-connected converter at time t; c 1e.t is the interaction participation factor between the e-th grid-type converter and the first grid-type converter at time t, c 2e.t is the interaction participation factor between the e-th grid-type converter and the second grid-type converter at time t, ..., c ne.t is the interaction participation factor between the e-th grid-type converter and the n-th grid-type converter at time t; p 1.t is the unbalanced power of the first grid-connected converter at time t, p 2.t is the unbalanced power of the second grid-connected converter at time t, ..., p n.t is 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.

[0036] Optionally, determining the virtual rotor angle of each of the grid-connected converters comprises:

[0037] Obtaining an angular acceleration of each of the grid-type converters according to the target unbalanced power and inertia of each of the grid-type converters;

[0038] The angular acceleration of each of the grid-type converters is integrated to obtain the virtual rotor angle of each of the grid-type converters.

[0039] In a second aspect, an embodiment of the present disclosure further provides a virtual rotor angle prediction device under a fault scenario, which is applied to a fully grid-connected converter interface power supply power system. The virtual rotor angle prediction device under a fault scenario includes:

[0040] A determination module, used to determine the current coupling degree between each of the grid-type converters and the reference grid-type converter under each fault;

[0041] A fitting module, used for fitting and obtaining an unbalanced power model of each of the grid-type converters according to the coupling degree data and unbalanced power data of each of the grid-type converters at each moment in the target period;

[0042] A single fault prediction module, for determining the target unbalanced power of each of the grid-type converters at the next moment according to the unbalanced power model, the current unbalanced power and the current coupling degree of each of the grid-type converters if the fault type is a single fault;

[0043] A sequential fault prediction module, for determining a coupling weighting factor of each fault if the fault type is a sequential fault; determining the mutual coupling degree of each of the grid-type converters according to the coupling weighting factor of each fault and the set of the current coupling degree of each of the grid-type converters under each fault; determining the target unbalanced power of each of the grid-type converters at the next moment according to the unbalanced power model of each of the grid-type converters, the current unbalanced power and the mutual coupling degree;

[0044] The virtual rotor angle calculation module is used to determine the virtual rotor angle of each of the grid-type converters according to the target unbalanced power and the target inertia of each of the grid-type converters.

[0045] In a third aspect, an embodiment of the present disclosure further provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a method for predicting a virtual rotor angle of a grid-type converter under a fault scenario as described in any embodiment of the present disclosure.

[0046] The disclosed embodiment determines the current coupling degree of each grid-type converter under each fault; fits and obtains the unbalanced power model of each grid-type converter according to the coupling degree data and unbalanced power data of each grid-type converter at each moment in the simulation period; if the fault type is a single fault, the target unbalanced power of each grid-type converter at the next moment is determined according to the unbalanced power model, current unbalanced power and current coupling degree of each grid-type converter; if the fault type is a sequential fault, the coupling weighting factor of each fault is determined; the interactive coupling degree of each grid-type converter is determined according to the set of the coupling weighting factor of each fault and the current coupling degree of each grid-type converter under each fault; the target unbalanced power of each grid-type converter at the next moment is determined according to the unbalanced power model, current unbalanced power and interactive coupling degree of each grid-type converter; the virtual rotor angle of each grid-type converter is determined according to the target unbalanced power and target inertia of each grid-type converter. Therefore, this scheme can quickly predict the virtual rotor angular motion trend of the full-grid converter interface power supply power system under fault scenarios, thereby suppressing the occurrence of oscillation and out-of-step that may occur in the power system under fault scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0048] Figure 1 A schematic flow chart of a method for predicting a virtual rotor angle of a grid-connected converter under a fault scenario provided by an embodiment of the present disclosure;

[0049] Figure 2 A flowchart of a step of determining the current coupling degree of each grid-connected converter under each fault provided by an embodiment of the present disclosure;

[0050] Figure 3 A flowchart of steps for determining a reference grid-type converter provided in an embodiment of the present disclosure;

[0051] Figure 4 A flowchart of steps for determining a target unbalanced power of each grid-connected converter at the next moment when the fault type is a single fault provided by an embodiment of the present disclosure;

[0052] Figure 5 A flowchart of steps for determining a target unbalanced power of each grid-connected converter at the next moment when the fault type is a sequential fault provided by an embodiment of the present disclosure;

[0053] Figure 6 A flowchart of steps for determining a virtual rotor angle of each grid-connected converter provided in an embodiment of the present disclosure;

[0054] Figure 7 A schematic diagram of the structure of a virtual rotor angle prediction device under a fault scenario provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0055] In order to enable those skilled in the art to better understand the scheme of the present disclosure, the technical scheme in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present disclosure.

[0056] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, 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 "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0057] Figure 1 A flowchart of a method for predicting a virtual rotor angle of a grid-type converter under a fault scenario provided by an embodiment of the present disclosure is provided. This embodiment can be applied to a full grid-type converter interface power supply system including at least two grid-type converters to predict the virtual rotor angle of each grid-type converter. The method can be executed by a virtual rotor angle prediction device under a fault scenario, which can be implemented in hardware and / or software. The method specifically includes the following steps:

[0058] S110: Determine the current coupling degree between each grid-type converter and the reference grid-type converter under each fault.

[0059] Among them, the grid-type converter can realize the conversion of electric energy of different voltage levels, different frequencies and different phases, and can actively participate in the construction and stable control of the power grid. The grid-type converter that participates in the operation of the full grid-type converter interface power supply power system to the greatest extent is the benchmark grid-type converter. The coupling degree refers to the degree of influence between each two grid-type converters. Specifically, the ratio of the component items involving the relevant grid-type converter in the electromagnetic power expression of a grid-type converter to the benchmark item of another grid-type converter is used as the coupling degree between the two grid-type converters. This step determines the current coupling degree between each grid-type converter and the benchmark grid-type converter in the full grid-type converter interface power supply power system under each fault, that is, the current participation degree of each grid-type converter in the power system is obtained based on the benchmark grid-type converter, thereby obtaining the current degree of influence of each grid-type converter on the power system, so as to accurately predict the change of each grid-type converter at the next moment according to the current degree of influence of each grid-type converter on the power system.

[0060] S120, fitting and obtaining an unbalanced power model of each grid-type converter according to the coupling degree data and unbalanced power data of each grid-type converter at each moment in the target period.

[0061] Among them, unbalanced power is the difference between mechanical power and electromagnetic power. Since mechanical power is constant by default, the change of unbalanced power actually reflects the change of electromagnetic power. Mechanical power and electromagnetic power are parameters of the virtual synchronous generator technology used by the grid-type converter. Mechanical power is equivalent to the active power command value, and electromagnetic power is the active power output by the virtual synchronous generator (active power output value). Unbalanced power = active power command value - active power output value. The unbalanced power model is the formula with the highest fitting degree obtained by fitting the coupling degree data and unbalanced power data of each grid-type converter at each moment in the target period.

[0062] Specifically, for each existing simulation period, by performing statistical analysis and summarizing the coupling degree data and unbalanced power data of each grid-type converter at each moment in the existing simulation period, and constructing a function with the help of fitting technology, it is possible to characterize the explicit expression formula for the correlation between the state quantity at the later moment and the state quantity at the previous moment in a shorter period of time, thereby obtaining the unbalanced power model of each grid-type converter.

[0063] S130: If the fault type is a single fault, determine the target unbalanced power of each grid-type converter at the next moment according to the unbalanced power model, current unbalanced power and current coupling degree of each grid-type converter.

[0064] Among them, a single fault refers to a fault that occurs in a single location and a single period of time in the power system. According to the unbalanced power model of each grid-type converter, the proportional weighted value of each grid-type converter can be obtained, that is, the proportion coefficient of the current unbalanced power under the coupling degree between each grid-type converter and the remaining grid-type converters. According to the current coupling degree of each grid-type converter, the coupling degree between each grid-type converter and the remaining grid-type converters can be obtained, that is, the ratio of the current coupling degree of the grid-type converter to be predicted to the current coupling degree of another grid-type converter is the coupling degree between the two grid-type converters. The current unbalanced power of each grid-type converter can be the target unbalanced power determined at the previous moment or directly obtained. Therefore, according to the proportional weighted value of each grid-type converter, the current unbalanced power and the coupling degree with each other grid-type converter, the target unbalanced power of each grid-type converter at the next moment is determined.

[0065] S140. If the fault type is a sequential fault, determine the coupling weighting factor of each fault; determine the interactive coupling degree of each grid-type converter based on the coupling weighting factor of each fault and the set of the current coupling degree of each grid-type converter under each fault; determine the target unbalanced power of each grid-type converter at the next moment based on the unbalanced power model, current unbalanced power and interactive coupling degree of each grid-type converter.

[0066] Among them, sequential faults refer to faults that occur in multiple locations, a single period or multiple periods of the power system, that is, faults that occur simultaneously in multiple locations or faults that occur at different times in multiple locations. The coupling weighting factor can be given comprehensively based on the dominant mode of each fault that constitutes the sequential faults (two-group mode division, that is, the division of the leading group and the remaining group) and the sequential fault time difference (the fault time difference is the time interval between the two sequential faults. If the faults occur at the same time, the sequential fault time difference is 0). The coupling weighting factor indicates the degree of influence of each fault on each other. For the sequential fault scenario, based on the idea of ​​coupling superposition, according to the coupling weighting factor of each fault and the set of the current coupling degree of each grid-type converter under each fault, the interactive coupling capability of each grid-type converter can be characterized when multiple faults occur.

[0067] Specifically, the proportional weighted value of each grid-type converter can be obtained according to the unbalanced power model of each grid-type converter, that is, the weight coefficient of the current unbalanced power under the coupling degree between each grid-type converter and the remaining grid-type converters. According to the coupling weighting factor of each fault and the current coupling degree of each grid-type converter under each fault, the degree of interactive coupling between each grid-type converter and the remaining grid-type converters under consecutive faults can be obtained. The current unbalanced power of each grid-type converter can be the target unbalanced power determined at the previous moment or directly obtained. Therefore, according to the proportional weighted value of each grid-type converter, the current unbalanced power and the degree of interactive coupling with each other grid-type converter, the target unbalanced power of each grid-type converter at the next moment is determined.

[0068] S150: Determine a virtual rotor angle of each grid-type converter according to a target unbalanced power and a target inertia of each grid-type converter.

[0069] Among them, the target inertia refers to the inertia parameter value of the grid-type converter. According to the target unbalanced power and inertia of each grid-type converter, the acceleration of each grid-type converter can be obtained; by integrating the acceleration of each grid-type converter, the virtual rotor angle of each grid-type converter can be obtained.

[0070] The disclosed embodiment determines the current coupling degree of each grid-type converter under each fault; fits and obtains the unbalanced power model of each grid-type converter according to the coupling degree data and unbalanced power data of each grid-type converter at each moment in the simulation period; if the fault type is a single fault, the target unbalanced power of each grid-type converter at the next moment is determined according to the unbalanced power model, current unbalanced power and current coupling degree of each grid-type converter; if the fault type is a sequential fault, the coupling weighting factor of each fault is determined; the interactive coupling degree of each grid-type converter is determined according to the set of the coupling weighting factor of each fault and the current coupling degree of each grid-type converter under each fault; the target unbalanced power of each grid-type converter at the next moment is determined according to the unbalanced power model, current unbalanced power and interactive coupling degree of each grid-type converter; the virtual rotor angle of each grid-type converter is determined according to the target unbalanced power and target inertia of each grid-type converter. Therefore, this scheme can quickly predict the virtual rotor angular motion trend of the full-grid converter interface power supply power system under fault scenarios, thereby suppressing the occurrence of oscillation and out-of-step that may occur in the power system under fault scenarios.

[0071] Based on the above embodiment, optionally, Figure 2 A flowchart of the steps of determining the current coupling degree of each grid-connected converter under each fault is provided in an embodiment of the present disclosure. Figure 2 As shown, the steps for determining the current coupling degree between each grid-type converter and the reference grid-type converter under each fault are described:

[0072] S210 . Under each fault condition, determine a reference grid-type converter according to the inertia of each grid-type converter and the current virtual rotor angular velocity.

[0073] Among them, the benchmark grid-type converter is the grid-type converter that participates most in the operation of the full grid-type converter interface power supply power system. Taking this grid-type converter as the standard facilitates obtaining the current participation degree of each grid-type converter in the power system.

[0074] Specifically, under each fault, the grid-type converter that participates the most in the overall dynamic behavior is defined as the benchmark grid-type converter. Therefore, under each fault, the degree of participation of each grid-type converter in the overall dynamic behavior can be calculated according to the inertia of each grid-type converter and the current virtual rotor angular velocity, thereby determining the grid-type converter that participates the most in the overall dynamic behavior.

[0075] S220: Obtain the current active power component factor of each grid-type converter under each fault and the standard active power component factor of the reference grid-type converter.

[0076] Among them, the current active power component factors of each grid-type converter (components in the active power (electromagnetic power) expression) and the standard active power component factors of the reference grid-type converter (components in the active power (electromagnetic power) expression) can be directly obtained. The current active power component factors of the grid-type converter include: internal potential, admittance between the reference grid-type converter, virtual rotor angle, and impedance angle between the reference grid-type converter, etc. The standard active power component factors of the reference grid-type converter include: internal potential, virtual rotor angle, and self-impedance angle, etc.

[0077] S230: Determine the current coupling degree of each grid-type converter under each fault according to the current active power component factor of each grid-type converter under each fault and the standard active power component factor of the reference grid-type converter.

[0078] Exemplarily, the current coupling degree of any grid-connected converter under a fault is:

[0079]

[0080] Among them, t is the current time, C ij.t is the current coupling degree of grid-connected converter j at time t, E i (t) is the internal potential of the reference grid-connected converter i at time t, E j (t) is the internal potential of grid-connected converter j at time t, Yij (t) is the admittance between the reference grid-type converter i and the grid-type converter j at time t, δ i (t) is the virtual rotor angle of the reference grid-connected converter i at time t, δ j (t) is the virtual rotor angle of grid-connected converter j at time t, θ ij (t) is the impedance angle between the reference grid-type converter i and the grid-type converter j at time t, θ ii (t) is the self-impedance angle of the grid-connected converter i, and i and j are both positive integers.

[0081] Based on the above embodiment, optionally, Figure 3 A flowchart of the steps of determining a reference grid-type converter provided by an embodiment of the present disclosure. Figure 3 As shown, the steps of determining the reference grid-type converter according to the inertia of each grid-type converter and the current virtual rotor angular velocity are described:

[0082] S310. Determine the participation degree value of each grid-type converter in the overall dynamic behavior according to the inertia of each grid-type converter and the current virtual rotor angular velocity.

[0083] Specifically, the formula for the value of the degree of participation in the overall dynamic behavior is:

[0084] Among them, J it is the inertia of grid-connected converter i at time t, ω it is the virtual rotor angular velocity of the grid-connected converter i at time t.

[0085] S320, according to the participation degree value of each grid-type converter in the overall dynamic behavior, select the grid-type converter with the largest overall dynamic behavior degree value as the benchmark grid-type converter.

[0086] Based on the above embodiment, optionally, Figure 4 A flowchart of the steps of determining the target unbalanced power of each grid-type converter at the next moment when the fault type is a single fault is provided in an embodiment of the present disclosure. Figure 4 As shown, if the fault type is a single fault, the steps of determining the target unbalanced power of each grid-type converter at the next moment are described:

[0087] S410: Obtain a proportional weighted value of each grid-type converter according to an unbalanced power model of each grid-type converter.

[0088] The proportional weighted value represents the weight coefficient of the current unbalanced power under the coupling degree between each grid-type converter and the other grid-type converters.

[0089] S420: Determine a participation factor between each grid-type converter and other grid-type converters according to a current coupling degree of each grid-type converter.

[0090] Exemplarily, the ratio of the current coupling degree of the grid-type inverter to be predicted to the current coupling degree of another grid-type inverter is the participation factor between the two grid-type inverters, that is, the coupling degree between each grid-type inverter and the remaining grid-type inverters. Therefore, the participation factor is not based on "screening the grid-type inverter with the largest overall dynamic behavior degree value as the benchmark grid-type inverter" to measure the coupling degree between any two grid-type inverters.

[0091] S430: Determine the target unbalanced power of each grid-type converter at the next moment according to the proportional weighted value of each grid-type converter, the current unbalanced power and the participation factor.

[0092] Specifically, the target unbalanced power p of the grid-connected converter i at the next moment is i.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 );

[0093] Among them, k0, k1, k2...k n is the proportional weighted value of the grid-connected converter m; t is the current moment; p m.t is the unbalanced power of the mth grid-connected converter at time t; c 1m.t is the participation factor between the mth grid-connected converter and the first grid-connected converter at time t, c 2m.t is the participation factor between the mth grid-connected converter and the second grid-connected converter at time t, ..., c nm.t is the participation factor between the mth grid-type converter and the nth grid-type converter at time t; p 1.t is the unbalanced power of the first grid-connected converter at time t, p 2.t is the unbalanced power of the second grid-connected converter at time t, ..., p n.t is the unbalanced power of the nth grid-connected converter at time t; m and n are both positive integers.

[0094] Based on the above embodiment, optionally, a set C of mutual coupling degrees of each grid-connected converter is t for:

[0095] Ct =k1×C t.1 +k2×C t.2 +…+k l ×C t.l ;

[0096] C t =[C1, C2, ..., C n ];

[0097] Where k1 is the coupling weighting factor of the first fault, k2 is the coupling weighting factor of the second fault, ..., k l is the coupling weighting factor of the first fault; C t.1 is the set of current coupling levels of each grid-connected converter under the first fault, C t.2 is the set of current coupling degrees of each grid-connected converter under the second fault, ..., C t.l is the set of current coupling degrees of each grid-type converter under the lth fault; C1 is the mutual coupling degree of the first grid-type converter, C2 is the mutual coupling degree of the second grid-type converter, ..., C n is the degree of interaction coupling of the nth grid-connected converter.

[0098] Based on the above embodiment, optionally, Figure 5 A flowchart of the steps of determining the target unbalanced power of each grid-connected converter at the next moment when the fault type is a sequential fault is provided in an embodiment of the present disclosure. Figure 5 As shown, if the fault type is a sequential fault, the steps of determining the target unbalanced power of each grid-connected converter at the next moment are described:

[0099] S510: Obtain a proportional weighted value of each grid-type converter according to an unbalanced power model of each grid-type converter.

[0100] The proportional weighted value represents the weight coefficient of the current unbalanced power under the coupling degree between each grid-type converter and the other grid-type converters.

[0101] S520. Calculate the interaction participation factor between each grid-type converter and other grid-type converters according to the interaction coupling degree of each grid-type converter.

[0102] Exemplarily, under consecutive faults, the ratio of the interactive coupling degree of the grid-type converter to be predicted to the interactive coupling degree of another grid-type converter is the interactive participation factor between the two grid-type converters.

[0103] S530: Calculate the target unbalanced power of each grid-type converter at the next moment according to the proportional weighted value of each grid-type converter, the current unbalanced power and the interaction participation factor.

[0104] For example, the target unbalanced power p of the grid-connected converter e at the next moment is 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 );

[0105] Among them, k0, k1, ... k n is the proportional weighted value of the grid-connected converter e; t is the current moment; p e.t is the unbalanced power of the e-th grid-connected converter at time t; c 1e.t is the interaction participation factor between the e-th grid-connected converter and the first grid-connected converter at time t, c 2e.t is the interaction participation factor between the e-th grid-type converter and the second grid-type converter at time t, ..., c ne.t is the interaction participation factor between the e-th grid-type converter and the n-th grid-type converter at time t; p 1.t is the unbalanced power of the first grid-connected converter at time t, p 2.t is the unbalanced power of the second grid-connected converter at time t, ..., p n.t is the unbalanced power of the nth grid-connected converter at time t; e and n are both positive integers, and n is the number of grid-connected converters.

[0106] Based on the above embodiment, optionally, Figure 6 A flowchart of the steps of determining the virtual rotor angle of each grid-connected converter provided by an embodiment of the present disclosure is shown. Figure 6 As shown, the steps for determining the virtual rotor angle of each grid-connected converter are described:

[0107] S610: Obtain the angular acceleration of each grid-type converter according to the target unbalanced power and inertia of each grid-type converter.

[0108] S620: Integrate the angular acceleration of each grid-type converter to obtain a virtual rotor angle of each grid-type converter.

[0109] Figure 7A schematic diagram of the structure of a virtual rotor angle prediction device under a fault scenario provided by an embodiment of the present disclosure, wherein the virtual rotor angle prediction device under a fault scenario is applied to a fully grid-connected converter interface power supply power system, and comprises:

[0110] A determination module 110, for determining a current coupling degree between each grid-type converter and a reference grid-type converter under each fault;

[0111] A fitting module 120, configured to obtain an unbalanced power model of each grid-type converter by fitting according to the coupling degree data and unbalanced power data of each grid-type converter at each moment in the target period;

[0112] A single fault prediction module 130 is used to determine the target unbalanced power of each grid-type converter at the next moment according to the unbalanced power model, current unbalanced power and current coupling degree of each grid-type converter if the fault type is a single fault;

[0113] The sequential fault prediction module 140 is used to determine the coupling weighting factor of each fault if the fault type is a sequential fault; determine the mutual coupling degree of each grid-type converter according to the coupling weighting factor of each fault and the set of the current coupling degree of each grid-type converter under each fault; determine the target unbalanced power of each grid-type converter at the next moment according to the unbalanced power model, current unbalanced power and mutual coupling degree of each grid-type converter;

[0114] The virtual rotor angle calculation module 150 is used to determine the virtual rotor angle of each grid-type converter according to the target unbalanced power and target inertia of each grid-type converter.

[0115] The embodiment of the present disclosure determines the current coupling degree of each grid-type converter under each fault through the determination module 110; the fitting module 120 fits the unbalanced power model of each grid-type converter according to the coupling degree data and unbalanced power data of each grid-type converter at each moment in the simulation period; the single fault prediction module 130 is used to determine the target unbalanced power of each grid-type converter at the next moment according to the unbalanced power model, current unbalanced power and current coupling degree of each grid-type converter if the fault type is a single fault; the sequential fault prediction module 140 is used to determine the target unbalanced power of each grid-type converter at the next moment if the fault type is a sequential fault. If the fault type is a successive fault, the successive fault prediction module 140 determines the coupling weighting factor of each fault; according to the coupling weighting factor of each fault and the set of the current coupling degree of each grid-type converter under each fault, the interactive coupling degree of each grid-type converter is determined; according to the unbalanced power model, current unbalanced power and interactive coupling degree of each grid-type converter, the target unbalanced power of each grid-type converter at the next moment is determined; the virtual rotor angle calculation module 150 determines the virtual rotor angle of each grid-type converter according to the target unbalanced power and target inertia of each grid-type converter. Therefore, this scheme can quickly predict the virtual rotor angle movement trend of the power system of the full grid-type converter interface power supply under the fault scenario, thereby suppressing the occurrence of oscillation out-of-step that may occur in the power system under the fault scenario.

[0116] Based on the above embodiment, optionally, the determining module includes:

[0117] A reference grid-type converter determination unit, used to determine a reference grid-type converter according to the inertia of each grid-type converter and the current virtual rotor angular velocity under each fault;

[0118] An active power component factor acquisition unit, used to acquire the current active power component factor of each grid-type converter and the standard active power component factor of the reference grid-type converter under each fault;

[0119] The current coupling degree calculation unit is used to determine the current coupling degree of each grid-type converter under each fault according to the current active power component factor of each grid-type converter under each fault and the standard active power component factor of the reference grid-type converter.

[0120] On the basis of the above embodiment, optionally, the reference grid-type converter determination unit is specifically used for:

[0121] Determine the participation degree value of each grid-type converter in the overall dynamic behavior according to the inertia of each grid-type converter and the current virtual rotor angular velocity;

[0122] According to the participation degree value of each grid-type converter in the overall dynamic behavior, the grid-type converter with the largest overall dynamic behavior degree value is selected as the benchmark grid-type converter.

[0123] Based on the above embodiment, optionally, the single fault prediction module includes:

[0124] A first proportional weighted value determining unit, configured to obtain a proportional weighted value of each grid-type converter according to an unbalanced power model of each grid-type converter;

[0125] A participation factor determination unit, used to determine the participation factor between each grid-type converter and other grid-type converters according to the current coupling degree of each grid-type converter;

[0126] The first target unbalanced power calculation unit is used to determine the target unbalanced power of each grid-type converter at the next moment according to the proportional weighted value of each grid-type converter, the current unbalanced power and the participation factor.

[0127] Based on the above embodiment, optionally, the sequential failure prediction module includes:

[0128] A second proportional weighted value determination unit, configured to obtain a proportional weighted value of each grid-type converter according to an unbalanced power model of each grid-type converter;

[0129] An interaction participation factor determination unit, used to calculate the interaction participation factor between each grid-type converter and other grid-type converters according to the degree of interaction coupling of each grid-type converter;

[0130] The second target unbalanced power calculation unit is used to calculate the target unbalanced power of each grid-type converter at the next moment according to the proportional weighted value of each grid-type converter, the current unbalanced power and the interaction participation factor.

[0131] Based on the above embodiment, optionally, the virtual rotor angle calculation module includes:

[0132] An acceleration calculation unit, used for obtaining an angular acceleration of each grid-type converter according to a target unbalanced power and inertia of each grid-type converter;

[0133] The virtual rotor angle calculation unit is used to integrate the angular acceleration of each grid-type converter to obtain the virtual rotor angle of each grid-type converter.

[0134] An embodiment of the present disclosure also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, a virtual rotor angle prediction method for a grid-type converter under a fault scenario as provided in any embodiment of the present disclosure is implemented.

[0135] The computer storage medium of the embodiment of the present disclosure may adopt any combination of one or more computer-readable media. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium may be, for example, but not limited to: an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. The computer-readable storage medium includes (a non-exhaustive list): an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an 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 of the above. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, device or device.

[0136] A computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, the data signal carrying a computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0137] The program code contained on the computer-readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wire, optical cable, radio frequency (RF), etc., or any suitable combination of the foregoing.

[0138] Computer program code for performing the disclosed operations may be written in one or more programming languages ​​or a combination of multiple programming languages, including object-oriented programming languages ​​such as Java, Smalltalk, C++, Ruby, Go, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network (including a local area network (LAN) or a wide area network (WAN)), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet).

[0139] It will be appreciated by those skilled in the art that the term user terminal covers any suitable type of wireless user equipment, such as a mobile phone, a portable data processing device, a portable web browser or a vehicle-mounted mobile station.

[0140] In general, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor or other computing device, although the present disclosure is not limited thereto.

[0141] Embodiments of the present disclosure may be implemented by executing computer program instructions by a data processor of a mobile device, for example in a processor entity, or by hardware, or by a combination of software and hardware. The computer program instructions may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages.

[0142] The block diagram of any logic flow in the drawings of the present 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. A computer program may be stored on a memory. The memory may be of any type suitable for 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 memory devices and systems (digital versatile discs DVD or CD discs), etc. Computer-readable media may include non-transient storage media. A data processor may be of any type suitable for the local technical environment, such as but not limited to a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (Digital Signal Processing, DSP), an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), a programmable logic device (Field-Programmable Gate Array, FGPA) and a processor based on a multi-core processor architecture.

[0143] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of this disclosure can be achieved, and this document is not limited here.

[0144] The above specific implementations do not constitute a limitation on the protection scope of the present disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A virtual rotor angle prediction method for a grid-type converter under a fault scenario, applied to a full grid-type converter interface power supply power system, the system comprising at least two grid-type converters, characterized in that: include: Determining a current degree of coupling between each of the grid-connected converters and a reference grid-connected converter for each fault; According to the coupling degree data and unbalanced power data of each of the grid-type converters at each moment in the target period, fitting and obtaining an unbalanced power model of each of the grid-type converters; If the fault type is a single fault, determining the target unbalanced power of each of the grid-type converters at the next moment according to the unbalanced power model, the current unbalanced power and the current coupling degree of each of the grid-type converters; If the fault type is a sequential fault, determine the coupling weighting factor of each fault; Determine the mutual coupling degree of each grid-type converter according to the coupling weighting factor of each fault and the current coupling degree of each grid-type converter under each fault; determine the target unbalanced power of each grid-type converter at the next moment according to the unbalanced power model of each grid-type converter, the current unbalanced power and the mutual coupling degree; A virtual rotor angle of each of the grid-type converters is determined according to the target unbalanced power and the target inertia of each of the grid-type converters.

2. The virtual rotor angle prediction method of a grid-connected converter under a fault scenario according to claim 1 is characterized in that: The determining of the current coupling degree between each of the grid-type converters and the reference grid-type converter under each fault comprises: Under each fault, a reference grid-type converter is determined according to the inertia of each grid-type converter and the current virtual rotor angular velocity; Obtaining the current active power component factor of each grid-type converter under each fault and the standard active power component factor of the reference grid-type converter; According to the current active power component factor of each grid-type converter under each fault and the standard active power component factor of the reference grid-type converter, the current coupling degree of each grid-type converter under each fault is determined.

3. The virtual rotor angle prediction method of a grid-connected converter under a fault scenario according to claim 2 is characterized in that: The step of determining the reference grid-type converter according to the inertia of each grid-type converter and the current virtual rotor angular velocity comprises: Determining the degree of participation of each of the grid-type converters in the overall dynamic behavior according to the inertia of each of the grid-type converters and the current virtual rotor angular velocity; According to the participation degree value of each of the grid-type converters in the overall dynamic behavior, the grid-type converter with the largest overall dynamic behavior degree value is selected as the reference grid-type converter.

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

5. The virtual rotor angle prediction method of a grid-connected converter under a fault scenario according to claim 1, characterized in that: If the fault type is a single fault, determining the target unbalanced power of each of the grid-connected converters at the next moment includes: According to the unbalanced power model of each of the grid-type converters, obtaining a proportional weighted value of each of the grid-type converters; Determining a participation factor between each of the grid-type converters and the remaining grid-type converters according to a current coupling degree of each of the grid-type converters; The target unbalanced power of each of the grid-type converters at the next moment is determined according to the proportional weighted value, the current unbalanced power and the participation factor of each of the grid-type converters.

6. The virtual rotor angle prediction method of a grid-connected converter under a fault scenario according to claim 5, characterized in that: The target unbalanced power p of the grid-connected converter i at the next moment is i.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 ); Among them, k0, k1, k2...k n is the proportional weighted value of the grid-type converter m; t is the current moment; p m.t is the unbalanced power of the mth grid-connected converter at time t; c 1m.t is the participation factor between the mth grid-connected converter and the first grid-connected converter at time t, c 2m.t is the participation factor between the mth grid-connected converter and the second grid-connected converter at time t, ..., c nm.t is the participation factor between the mth grid-type converter and the nth grid-type converter at time t; p 1.t is the unbalanced power of the first grid-connected converter at time t, p 2.t is the unbalanced power of the second grid-connected converter at time t, ..., p n.t is the unbalanced power of the nth grid-connected converter at time t; m and n are both positive integers.

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

8. The method for predicting the virtual rotor angle of a grid-connected converter under a fault scenario according to claim 7, characterized in that: If the fault type is a sequential fault, determining the target unbalanced power of each of the grid-connected converters at the next moment includes: According to the unbalanced power model of each of the grid-type converters, obtaining a proportional weighted value of each of the grid-type converters; Calculating the interaction participation factor between each of the grid-type converters and the remaining grid-type converters according to the interaction coupling degree of each of the grid-type converters; The target unbalanced power of each of the grid-type converters at the next moment is calculated according to the proportional weighted value, the current unbalanced power and the interaction participation factor of each of the grid-type converters.

9. The method for predicting the virtual rotor angle of a grid-connected converter under a fault scenario according to claim 8, characterized in that: The target unbalanced power p of the grid-connected converter e at the next moment is 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 ); Among them, k0, k1, ... k n is the proportional weighted value of the grid-type converter e; t is the current moment; p e.t is the unbalanced power of the e-th grid-connected converter at time t; c 1e.t is the interaction participation factor between the e-th grid-type converter and the first grid-type converter at time t, c 2e.t is the interaction participation factor between the e-th grid-type converter and the second grid-type converter at time t, ..., c ne.t is the interaction participation factor between the e-th grid-type converter and the n-th grid-type converter at time t; p 1.t is the unbalanced power of the first grid-connected converter at time t, p 2.t is the unbalanced power of the second grid-connected converter at time t, ..., p n.t is 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 of a grid-connected converter under a fault scenario according to claim 1, characterized in that: The determining of the virtual rotor angle of each of the grid-connected converters comprises: Obtaining an angular acceleration of each of the grid-type converters according to the target unbalanced power and inertia of each of the grid-type converters; The angular acceleration of each of the grid-type converters is integrated to obtain the virtual rotor angle of each of the grid-type converters.

11. A virtual rotor angle prediction device under fault scenarios, applied to a full grid-type converter interface power supply power system, characterized in that: include: A determination module, used to determine the current coupling degree between each of the grid-type converters and the reference grid-type converter under each fault; A fitting module, used for fitting and obtaining an unbalanced power model of each of the grid-type converters according to the coupling degree data and unbalanced power data of each of the grid-type converters at each moment in the target period; A single fault prediction module, for determining, if the fault type is a single fault, a target unbalanced power of each of the grid-type converters at the next moment according to the unbalanced power model, the current unbalanced power and the current coupling degree of each of the grid-type converters; A sequential fault prediction module, for determining a coupling weighting factor of each fault if the fault type is a sequential fault; Determine the mutual coupling degree of each grid-type converter according to the coupling weighting factor of each fault and the current coupling degree of each grid-type converter under each fault; determine the target unbalanced power of each grid-type converter at the next moment according to the unbalanced power model of each grid-type converter, the current unbalanced power and the mutual coupling degree; The virtual rotor angle calculation module is used to determine the virtual rotor angle of each of the grid-type converters according to the target unbalanced power and the target inertia of each of the grid-type converters.

12. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for predicting a virtual rotor angle of a grid-type converter under a fault scenario as described in any one of claims 1 to 10 is implemented.

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