Method for constructing grid commutated converter admittance model and related device

Abstract

The application discloses a power grid commutation converter admittance model construction method and related equipment, and the method comprises the steps of: according to the commutation trigger control and the nonlinear commutation process, analyzing and determining the offset of the commutation converter at the commutation trigger time and the commutation end time under small disturbance; constructing the state function of the commutation converter based on the single side modulation theory; combining the state function of the commutation converter and the electrical quantity of the AC side and DC side of the commutation converter in each state, establishing the small disturbance dynamic equation of the DC voltage and AC current of the commutation converter; and according to the offset, the state function and the small disturbance dynamic equation, establishing the corresponding wide-band AC side and DC side admittance model of the commutation converter. The application solves a number of technical problems in the modeling of the small signal admittance model of the high-voltage direct-current transmission system, and improves the accuracy of the wide-band AC side and DC side admittance model.

Description

Technical Field

[0001] This application relates to the field of power grid assessment, and more specifically, to a method for constructing an admittance model for a power grid commutator and related equipment. Background Technology

[0002] High-voltage direct current (HVDC) transmission systems based on grid-commutated converters have advantages such as large transmission capacity, low loss, and mature technology, and are widely used in asynchronous interconnection, energy integration, and long-distance power transmission. However, with the continuous deepening of power electronics, the broadband resonance problem of DC systems is becoming increasingly prominent. Numerous harmonic resonance events have occurred in existing HVDC projects.

[0003] Currently, small-signal admittance models are widely used to analyze such resonant stability problems, and accurately establishing small-signal admittance models for broadband high-voltage direct current transmission systems is of great significance for achieving reliable resonant stability.

[0004] For the modeling problem of small-signal admittance in high-voltage direct current (HVDC) transmission systems, existing technical solutions typically start with the AC / DC side mapping function, using double Fourier decomposition or impulse equivalence methods to solve the small-signal dynamics of the AC / DC side mapping function, and further consider the small-signal dynamics of the AC / DC side electrical quantities to establish the small-signal admittance model of the HVDC transmission system. However, such methods still have the following problems:

[0005] First, it is impossible to consider the impact of the nonlinear characteristics introduced by the converter in the commutation stage of the high-voltage direct current transmission system on the small-signal admittance;

[0006] Second, it is impossible to provide an accurate mathematical description of the mapping function that characterizes the converter state (commutation state, non-commutation state) that takes into account the effects of multiple harmonics.

[0007] Third, it cannot account for the impact of the large number of harmonic components present in the converter under steady state on the small-signal admittance.

[0008] Based on the above actual situation, this application proposes a scheme for constructing the admittance model of the power grid phase-commutation converter, which solves several technical problems faced in modeling the small-signal admittance model of the high-voltage direct current transmission system. Summary of the Invention

[0009] In view of this, this application provides a method and related equipment for constructing the admittance model of a power grid phase-commutation converter, which solves several technical problems in modeling the small-signal admittance model of a high-voltage direct current transmission system and improves the accuracy of the wide-band AC / DC side admittance model.

[0010] A method for constructing an admittance model for a power grid phase-commutated converter includes:

[0011] Based on the synchronous trigger control of the converter and the nonlinear commutation process, the offset of the converter at the commutation trigger time and the commutation end time under small disturbance is analyzed and determined.

[0012] The state function of the converter is constructed based on the unilateral modulation theory;

[0013] Based on the state function of the converter and the AC / DC electrical quantities of the converter shown in each state, the small-disturbance dynamic equations of the converter's DC voltage and AC current are established.

[0014] Based on the offset, the state function, and the small disturbance dynamic equation, a wideband AC / DC side admittance model corresponding to the converter is established.

[0015] Optionally, the construction of the converter's state function based on unilateral modulation theory includes:

[0016] Based on the commutation trigger time and the commutation end time of the converter, the state value of the converter in each time period is determined;

[0017] Based on the input signal of single-sided modulation, and the actual firing angle and firing overlap angle of the converter in steady state, the offset actual firing angle and the offset firing overlap angle are determined, wherein the firing overlap angle is the sum of the actual firing angle and the commutation overlap angle;

[0018] Based on the actual offset trigger angle, the offset trigger overlap angle, and the state values ​​corresponding to each time period, the state function of the converter is obtained analytically according to the single-sided modulation theory.

[0019] Optionally, by combining the state function of the converter and the AC / DC side electrical quantities of the converter shown in each state, small-disturbance dynamic equations for the DC voltage and AC current of the converter are established, including:

[0020] Based on the state function of the converter, the expressions for the DC voltage and AC current of the converter are determined;

[0021] The expressions for DC voltage and AC current are linearized to generate small-disturbance dynamic equations for the DC voltage and AC current of the converter.

[0022] Optionally, the offset corresponding to the commutation trigger moment is:

[0023] ΔT f (t)=Δα r (t) / [ω0-α r ′ ,s (t fi,0 )]

[0024] Among them, tfi α is the time when the trigger signal is generated. r,s and Δα r The actual trigger reference angle α r Medium-steady-state harmonic components and small disturbances, actual triggering reference angle α r Triggering reference angle α ord Phase θ of the phase-locked loop output PLL Subtracting the two, we get ω0 as the fundamental frequency angular velocity.

[0025] Optionally, the offset corresponding to the commutation end time is:

[0026]

[0027]

[0028] Where, α r,s and Δα r The actual trigger reference angle α r Medium steady-state harmonic components and small disturbances, i 2d and i 2q i 2a In the dq-axis component of the power grid in the dq coordinate system, i dc This refers to the DC current at the DC-side outlet of the converter. and These are the synchronization phases based on the fundamental frequency positive sequence phase, corresponding to the start and end times of commutation, respectively. f1,0 and t e1,0 T represents the start and end times of commutation in steady state. μ0 This represents the time length corresponding to the commutation overlap angle under steady-state conditions.

[0029] Optionally, the state function of the converter is:

[0030]

[0031] Among them, s CSi (t) and s NCSi (t) represents the commutation state CS. i and non-commutation state NCS i The state function, The synchronization phase is based on the positive sequence phase of the fundamental frequency, α(t) is the offset actual trigger angle, and δ(t) is the offset trigger overlap angle.

[0032] Optionally, the small-disturbance dynamic equations for the converter's DC voltage and AC current are as follows:

[0033]

[0034] Where, ΔU dc ΔIa , ΔI dc and ΔA r G represents the column vector composed of DC voltage, AC current, d-axis component of AC voltage, q-axis component of AC voltage, DC current, and Fourier coefficients of small disturbance harmonics at the actual firing angle. uk and G ik (k = 1, 2, 3, 4) represents the harmonic transfer matrix.

[0035] A device for constructing an admittance model for a power grid phase-commutator includes:

[0036] The offset unit is used to analyze and determine the offset of the converter at the commutation trigger time and the commutation end time under small disturbances, based on the converter synchronous trigger control and nonlinear commutation process.

[0037] A state function unit is used to construct the state function of the converter based on the one-sided modulation theory.

[0038] The dynamic equation unit is used to establish the small-disturbance dynamic equations of the converter's DC voltage and AC current by combining the state function of the converter and the AC and DC side electrical quantities of the converter shown in each state.

[0039] The admittance model unit is used to establish the wideband AC / DC side admittance model corresponding to the converter based on the offset, the state function, and the small disturbance dynamic equation.

[0040] A device for constructing an admittance model of a power grid phase-commutated converter includes a memory and a processor;

[0041] The memory is used to store programs;

[0042] The processor is used to execute the program to implement the various steps of the above-described method for constructing the admittance model of a grid-commutated converter.

[0043] A readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for constructing the admittance model of a grid-commutated converter.

[0044] As can be seen from the above technical solutions, the method and related equipment for constructing a power grid commutator admittance model provided in this application first analyze and determine the offset of the converter at the commutation triggering moment and the commutation ending moment under small disturbances, based on the converter synchronous triggering control and nonlinear commutation process. Then, the state function of the converter is constructed based on the single-sided modulation theory. Combining the state function of the converter and the AC and DC side electrical quantities of the converter shown in each state, the small disturbance dynamic equations of the converter DC voltage and AC current are established. Finally, based on the offset, the state function, and the small disturbance dynamic equations, a broadband AC and DC side admittance model corresponding to the converter is established.

[0045] This application considers the synchronous triggering control and nonlinear commutation process of the converter, and accurately solves for the offset at the start and end times of the converter triggering under small disturbances. Based on the single-sided modulation theory, a complete state function characterizing the state of the converter is established using the start and end times of triggering. Combining the state function and the AC and DC side electrical quantities of the converter under each state, dynamic equations for the DC voltage and AC current of the converter under small disturbances are established. Finally, based on the above technical characteristics, a broadband AC and DC side admittance model of the high-voltage direct current transmission system can be established.

[0046] Therefore, this application solves several technical problems in modeling small-signal admittance models of high-voltage direct current transmission systems and improves the accuracy of wideband AC / DC side admittance models. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0048] Figure 1 This is a flowchart illustrating a method for constructing an admittance model for a power grid phase-commutation converter, as disclosed in an embodiment of this application.

[0049] Figure 2 This is a schematic diagram of the synchronous triggering control structure disclosed in the embodiments of this application;

[0050] Figure 3 This is a schematic diagram of the structure of the six-pulse converter disclosed in the embodiments of this application;

[0051] Figure 4 This is a schematic diagram of unilateral modulation disclosed in an embodiment of this application;

[0052] Figure 5 This is a structural block diagram of a power grid phase-commutator admittance model construction device disclosed in this application;

[0053] Figure 6 This is a hardware structure block diagram of a power grid phase-commutation converter admittance model construction device disclosed in this application. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] This application can be used in a wide variety of general-purpose or special-purpose computing environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor devices, distributed computing environments including any of the above devices, etc.

[0056] This application provides a method for constructing an admittance model for a power grid phase-commutation converter. This method can be applied to various computer terminals or smart terminals, and its execution subject can be the processor or server of the computer terminal or smart terminal.

[0057] The following section introduces the solution proposed in this application. The technical solution is as follows, and details are provided below.

[0058] Figure 1 This is a flowchart of a method for constructing an admittance model for a power grid phase-commutated converter, as disclosed in an embodiment of this application.

[0059] The following is combined with Figure 1 This application will be described as follows: Figure 1 As shown, the method may include:

[0060] Step S1: Based on the converter synchronous trigger control and nonlinear commutation process, analyze and determine the offset of the converter at the commutation trigger time and the commutation end time under small disturbance.

[0061] Specifically, Figure 2 This is a schematic diagram of a synchronous trigger control structure, such as... Figure 2 As shown, synchronous triggering control is first based on the phase θ output by the phase-locked loop. PLL Generates 6 synchronous phases, namely θ si (i=1,2,3,…,6), with each synchronization phase differing by 60°.

[0062] The synchronization phase will be synchronized with the trigger reference angle α generated by the DC control system. ord A comparison is performed, and a trigger signal is generated at the intersection. Let t be the time when each trigger signal is generated.fi Then the triggering time will satisfy:

[0063]

[0064] Among them, A ord,s0 For α ord Medium steady-state DC component, α r,s and Δα r Indicates the actual triggering reference angle α r Medium-steady-state harmonic components and small disturbance quantities.

[0065] A first-order Taylor expansion yields the offset ΔT corresponding to the commutation trigger moment. f for:

[0066] ΔT f (t)=Δα r (t) / [ω0-α r ′ ,s (t fi,0 )]

[0067] Among them, t fi α is the time when the trigger signal is generated. r,s and Δα r The actual trigger reference angle α r Medium-steady-state harmonic components and small disturbances, actual triggering reference angle α r Triggering reference angle α ord Phase θ of the phase-locked loop output PLL Subtracting the two, we get ω0 as the fundamental frequency angular velocity.

[0068] Taking the commutation state with converter valves 1, 5, and 6 turned on as an example of the dynamics of the commutation process under small disturbances, under this commutation state, the converter phase a current i a At the end of commutation time t e1 The expression can be written as:

[0069]

[0070] After linearization, the offset ΔT corresponding to the commutation end time is obtained. μ (t) is:

[0071]

[0072]

[0073] Where, α r,s and Δα r The actual trigger reference angle α r Medium steady-state harmonic components and small disturbances, i 2d and i 2q i2a In the dq-axis component of the power grid in the dq coordinate system, i dc This refers to the DC current at the DC-side outlet of the converter. and These are the synchronization phases based on the positive sequence phase of the fundamental frequency, corresponding to the start and end times of commutation, respectively. f1,0 and t e1,0 T represents the start and end times of commutation in steady state. μ0 This represents the time length corresponding to the commutation overlap angle under steady-state conditions.

[0074] Step S2: Construct the state function of the converter based on the single-sided modulation theory.

[0075] Step S3: Based on the state function of the converter and the AC / DC side electrical quantities of the converter shown in each state, establish the small-disturbance dynamic equations for the DC voltage and AC current of the converter.

[0076] Step S4: Based on the offset, the state function, and the small disturbance dynamic equation, establish the wideband AC / DC side admittance model corresponding to the converter.

[0077] As can be seen from the above technical solutions, the method and related equipment for constructing a power grid commutator admittance model provided in this application first analyze and determine the offset of the converter at the commutation triggering moment and the commutation ending moment under small disturbances, based on the converter synchronous triggering control and nonlinear commutation process. Then, the state function of the converter is constructed based on the single-sided modulation theory. Combining the state function of the converter and the AC and DC side electrical quantities of the converter shown in each state, the small disturbance dynamic equations of the converter DC voltage and AC current are established. Finally, based on the offset, the state function, and the small disturbance dynamic equations, a broadband AC and DC side admittance model corresponding to the converter is established.

[0078] This application considers the synchronous triggering control and nonlinear commutation process of the converter, and accurately solves for the offset at the start and end times of the converter triggering under small disturbances. Based on the single-sided modulation theory, a complete state function characterizing the state of the converter is established using the start and end times of triggering. Combining the state function and the AC and DC side electrical quantities of the converter under each state, dynamic equations for the DC voltage and AC current of the converter under small disturbances are established. Finally, based on the above technical characteristics, a broadband AC and DC side admittance model of the high-voltage direct current transmission system can be established.

[0079] Therefore, this application solves several technical problems in modeling small-signal admittance models of high-voltage direct current transmission systems and improves the accuracy of wideband AC / DC side admittance models.

[0080] In some embodiments of this application, the process of constructing the state function of the converter based on the one-sided modulation theory in step S2 is described, which may specifically include:

[0081] Step S21: Determine the state value of the converter in each time period based on the commutation trigger time and the commutation end time of the converter.

[0082] Specifically, Figure 3 This is a schematic diagram of a six-pulse converter, as shown below. Figure 3 As shown, the core component of a high-voltage direct current transmission system is a six-pulse converter, where u j andi j (j=a,b,c) represents the three-phase voltage and current at the AC side outlet of the converter, u dc andi dc L represents the DC voltage and current at the DC-side outlet of the converter. c This indicates the leakage inductance of the converter transformer. Each converter valve in the converter is numbered from 1 to 6.

[0083] Based on each commutation start time (t) fi ) and commutation end time (t) ei This allows us to summarize the various commutation states of the converter (denoted as CS). i ) and non-commutation state (denoted as NCS) i As shown in Table 1:

[0084]

[0085] Table 1

[0086] s CSi (t) and s NCSi (t) represents the commutation state CS. i and non-commutation state NCS i The state function when the converter is in CS i / NCS i At time s, the state function takes the value 1; at other times, it takes the value 0. Then s CSi (t) / s NCSi (t) can be written as:

[0087]

[0088] Step S22: Based on the input signal of single-sided modulation, and the actual firing angle and firing overlap angle of the converter in steady state, determine the offset actual firing angle and the offset firing overlap angle, wherein the firing overlap angle is the sum of the actual firing angle and the commutation overlap angle.

[0089] Specifically, this invention derives the converter state function based on unilateral modulation theory. Figure 4 This is a schematic diagram of unilateral modulation, as shown below. Figure 4 As shown, the input signals for single-sided modulation are the modulating wave f(t) and the sawtooth carrier c(t). The modulator compares f(t) with the sawtooth carrier c(t) and generates a pulse sequence denoted by p[c,f]. The amplitudes of the pulse sequence and the sawtooth carrier are equal to 1 and 2π, respectively. The rising / falling edge of the pulse sequence is determined by the intersection of c(t) and 0 / f(t).

[0090] Define α(t) as the offset actual trigger angle and δ(t) as the offset trigger overlap angle as follows:

[0091]

[0092]

[0093] Where α0 is the actual firing angle of the converter under steady state, δ0 is the sum of the actual firing angle and the commutation overlap angle, and α r,s and Δα r The actual trigger reference angle α r Medium-steady-state harmonic components and small disturbances, where ω0 is the fundamental frequency angular velocity.

[0094] Step S23: Based on the actual offset trigger angle, the offset trigger overlap angle, and the state values ​​corresponding to each time period, the state function of the converter is obtained analytically according to the single-sided modulation theory.

[0095] Specifically, the state function of the converter is:

[0096]

[0097] Among them, s CSi (t) and s NCSi (t) represents the commutation state CS. i and non-commutation state NCS i The state function, The synchronization phase is based on the positive sequence phase of the fundamental frequency, α(t) is the offset actual trigger angle, and δ(t) is the offset trigger overlap angle.

[0098] In some embodiments of this application, the process of establishing the small-disturbance dynamic equations for the DC voltage and AC current of the converter by combining the state function of the converter and the AC / DC side electrical quantities of the converter shown in each state is described, and may specifically include:

[0099] Step S31: Based on the state function of the converter, determine the expressions for the DC voltage and AC current of the converter.

[0100] Specifically, the expressions for the converter's DC voltage and AC current are as follows:

[0101]

[0102] Among them, u dc,CSi / u dc,NCSi andi a,CSi / i a,NCSi They represent in CS i / NCS i The DC voltage and the AC current of phase a are in the middle.

[0103] Step S32: Linearize the expressions for DC voltage and AC current to generate small-disturbance dynamic equations for the DC voltage and AC current of the converter.

[0104] Specifically, the small-disturbance dynamic equations for the converter's DC voltage and AC current are as follows:

[0105]

[0106] Where, ΔU dc ΔI a , ΔI dc and ΔA r G represents the column vector composed of DC voltage, AC current, d-axis component of AC voltage, q-axis component of AC voltage, DC current, and Fourier coefficients of small disturbance harmonics at the actual firing angle. uk and G ik (k = 1, 2, 3, 4) represents the harmonic transfer matrix.

[0107] The following describes the grid commutator admittance model construction device provided in the embodiments of this application. The grid commutator admittance model construction device described below and the grid commutator admittance model construction method described above can be referred to each other.

[0108] See Figure 5 , Figure 5 This is a structural block diagram of a power grid phase-commutation converter admittance model construction device disclosed in an embodiment of this application.

[0109] like Figure 5 As shown, the grid commutator admittance model construction device may include:

[0110] Offset unit 110 is used to analyze and determine the offset of the converter at the commutation trigger time and the commutation end time under small disturbance based on the converter synchronous trigger control and nonlinear commutation process.

[0111] State function unit 120 is used to construct the state function of the converter based on unilateral modulation theory;

[0112] The dynamic equation unit 130 is used to combine the state function of the converter and the AC and DC side electrical quantities of the converter shown in each state to establish the small-disturbance dynamic equations of the DC voltage and AC current of the converter.

[0113] Admittance model unit 140 is used to establish a wideband AC / DC side admittance model corresponding to the converter based on the offset, the state function and the small disturbance dynamic equation.

[0114] As can be seen from the above technical solutions, the method and related equipment for constructing a power grid commutator admittance model provided in this application first analyze and determine the offset of the converter at the commutation triggering moment and the commutation ending moment under small disturbances, based on the converter synchronous triggering control and nonlinear commutation process. Then, the state function of the converter is constructed based on the single-sided modulation theory. Combining the state function of the converter and the AC and DC side electrical quantities of the converter shown in each state, the small disturbance dynamic equations of the converter DC voltage and AC current are established. Finally, based on the offset, the state function, and the small disturbance dynamic equations, a broadband AC and DC side admittance model corresponding to the converter is established.

[0115] This application considers the synchronous triggering control and nonlinear commutation process of the converter, and accurately solves for the offset at the start and end times of the converter triggering under small disturbances. Based on the single-sided modulation theory, a complete state function characterizing the state of the converter is established using the start and end times of triggering. Combining the state function and the AC and DC side electrical quantities of the converter under each state, dynamic equations for the DC voltage and AC current of the converter under small disturbances are established. Finally, based on the above technical characteristics, a broadband AC and DC side admittance model of the high-voltage direct current transmission system can be established.

[0116] Therefore, this application solves several technical problems in modeling small-signal admittance models of high-voltage direct current transmission systems and improves the accuracy of wideband AC / DC side admittance models.

[0117] Optionally, the state function unit includes:

[0118] The status value unit is used to determine the status value of the converter in each time period based on the commutation trigger time and the commutation end time of the converter.

[0119] A single-sided modulation unit is used to determine the offset actual firing angle and the offset firing overlap angle based on the single-sided modulation input signal, the actual firing angle and the firing overlap angle of the converter in steady state, wherein the firing overlap angle is the sum of the actual firing angle and the commutation overlap angle.

[0120] The function analysis unit is used to analyze the state function of the converter based on the actual offset trigger angle, the offset trigger overlap angle, and the state values ​​corresponding to each time period, according to the single-sided modulation theory.

[0121] Optionally, the dynamic equation unit includes:

[0122] The expression unit is used to determine the expressions for the DC voltage and AC current of the converter based on the state function of the converter;

[0123] The linearization unit is used to linearize the expressions for DC voltage and AC current to generate small-disturbance dynamic equations for the DC voltage and AC current of the converter.

[0124] Optionally, the offset corresponding to the commutation trigger moment is:

[0125] ΔT f (t)=Δα r (t) / [ω0-α r ′ ,s (t fi,0 )]

[0126] Among them, t fi α is the time when the trigger signal is generated. r,s and Δα r The actual trigger reference angle α r Medium-steady-state harmonic components and small disturbances, actual triggering reference angle α r Triggering reference angle α ord Phase θ of the phase-locked loop output PLL Subtracting the two, we get ω0 as the fundamental frequency angular velocity.

[0127] Optionally, the offset corresponding to the commutation end time is:

[0128]

[0129]

[0130] Where, α r,s and Δα r The actual trigger reference angle α r Medium steady-state harmonic components and small disturbances, i 2d and i 2q i 2a In the dq-axis component of the power grid in the dq coordinate system, i dc This refers to the DC current at the DC-side outlet of the converter. and These are the synchronization phases based on the fundamental frequency positive sequence phase, corresponding to the start and end times of commutation, respectively.f1,0 and t e1,0 T represents the start and end times of commutation in steady state. μ0 This represents the time length corresponding to the commutation overlap angle under steady-state conditions.

[0131] Optionally, the state function of the converter is:

[0132]

[0133] Among them, s CSi (t) and s NCSi (t) represents the commutation state CS. i and non-commutation state NCS i The state function, The synchronization phase is based on the positive sequence phase of the fundamental frequency, α(t) is the offset actual trigger angle, and δ(t) is the offset trigger overlap angle.

[0134] Optionally, the small-disturbance dynamic equations for the converter's DC voltage and AC current are as follows:

[0135]

[0136] Where, ΔU dc ΔI a , ΔI dc and ΔA r G represents the column vector composed of DC voltage, AC current, d-axis component of AC voltage, q-axis component of AC voltage, DC current, and Fourier coefficients of small disturbance harmonics at the actual firing angle. uk and G ik (k = 1, 2, 3, 4) represents the harmonic transfer matrix.

[0137] The grid commutator admittance model construction device provided in the application embodiment can be applied to grid commutator admittance model construction equipment. Figure 6 The hardware structure block diagram of the device for constructing the admittance model of the power grid commutator is shown, with reference to Figure 6 The hardware structure of the grid commutator admittance model construction device may include: at least one processor 1, at least one communication interface 2, at least one memory 3 and at least one communication bus 4;

[0138] In this embodiment of the application, the number of processor 1, communication interface 2, memory 3, and communication bus 4 is at least one, and processor 1, communication interface 2, and memory 3 communicate with each other through communication bus 4;

[0139] Processor 1 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention.

[0140] Memory 3 may include high-speed RAM, and may also include non-volatile memory, such as at least one disk storage device;

[0141] The memory stores a program, which the processor can call. The program is used for:

[0142] Based on the synchronous trigger control of the converter and the nonlinear commutation process, the offset of the converter at the commutation trigger time and the commutation end time under small disturbance is analyzed and determined.

[0143] The state function of the converter is constructed based on the unilateral modulation theory;

[0144] Based on the state function of the converter and the AC / DC electrical quantities of the converter shown in each state, the small-disturbance dynamic equations of the converter's DC voltage and AC current are established.

[0145] Based on the offset, the state function, and the small disturbance dynamic equation, a wideband AC / DC side admittance model corresponding to the converter is established.

[0146] Optionally, the refined and extended functions of the program can be referred to the above description.

[0147] This application embodiment also provides a readable storage medium that can store a program suitable for execution by a processor, the program being used for:

[0148] Based on the synchronous trigger control of the converter and the nonlinear commutation process, the offset of the converter at the commutation trigger time and the commutation end time under small disturbances is analyzed and determined.

[0149] The state function of the converter is constructed based on the unilateral modulation theory;

[0150] Based on the state function of the converter and the AC / DC electrical quantities of the converter shown in each state, the small-disturbance dynamic equations of the converter's DC voltage and AC current are established.

[0151] Based on the offset, the state function, and the small disturbance dynamic equation, a wideband AC / DC side admittance model corresponding to the converter is established.

[0152] Optionally, the refined and extended functions of the program can be referred to the above description.

[0153] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0154] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0155] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for constructing an admittance model for a power grid commutated converter, characterized in that, include: Based on the synchronous trigger control of the converter and the nonlinear commutation process, the offset of the converter at the commutation trigger time and the commutation end time under small disturbances is analyzed and determined. The state function of the converter is constructed based on the single-sided modulation theory, including: Based on the commutation trigger time and the commutation end time of the converter, the state value of the converter in each time period is determined; Based on the input signal of single-sided modulation, and the actual firing angle and firing overlap angle of the converter in steady state, the offset actual firing angle and the offset firing overlap angle are determined, wherein the firing overlap angle is the sum of the actual firing angle and the commutation overlap angle; Based on the actual offset firing angle, the offset firing overlap angle, and the state values ​​corresponding to each time period, the state function of the converter is analytically obtained according to the single-sided modulation theory. Based on the state function of the converter and the AC / DC side electrical quantities of the converter shown in each state, the small-disturbance dynamic equations for the DC voltage and AC current of the converter are established, including: Based on the state function of the converter, the expressions for the DC voltage and AC current of the converter are determined; The expressions for DC voltage and AC current are linearized to generate small-disturbance dynamic equations for the DC voltage and AC current of the converter. Based on the offset, the state function, and the small disturbance dynamic equation, a wideband AC / DC side admittance model corresponding to the converter is established.

2. The method according to claim 1, characterized in that, The offset corresponding to the commutation trigger moment is: Among them, t fi,0 α is the time when the trigger signal is generated. r,s and The actual trigger reference angle α r Medium-steady-state harmonic components and small disturbances, actual triggering reference angle α r Trigger reference angle Phase with phase-locked loop output Subtraction yields, This is the fundamental frequency angular velocity.

3. The method according to claim 1, characterized in that, The state function of the converter is: Among them, s CSi (t) and s NCSi (t) represents the commutation state CS. i and non-commutation state NCS i The state function, The synchronization phase is based on the positive sequence phase of the fundamental frequency, α(t) is the offset actual trigger angle, and δ(t) is the offset trigger overlap angle.

4. The method according to claim 1, characterized in that, The small-disturbance dynamic equations for the DC voltage and AC current of the converter are as follows: in, and G represents the column vector composed of DC voltage, AC current, the q-axis component of AC voltage, the d-axis component of AC voltage, DC current, and the Fourier coefficients of each order of small disturbance harmonics in the actual firing angle. uk and G ik Let k represent the harmonic transfer matrix, where k = 1, 2, 3, 4.

5. A device for constructing an admittance model for a power grid phase-commutated converter, characterized in that, include: The offset unit is used to analyze and determine the offset of the converter at the commutation trigger time and the commutation end time under small disturbances, based on the converter synchronous trigger control and nonlinear commutation process. The state function unit, used to construct the state function of the converter based on the one-sided modulation theory, includes: Based on the commutation trigger time and the commutation end time of the converter, the state value of the converter in each time period is determined; Based on the input signal of single-sided modulation, and the actual firing angle and firing overlap angle of the converter in steady state, the offset actual firing angle and the offset firing overlap angle are determined, wherein the firing overlap angle is the sum of the actual firing angle and the commutation overlap angle; Based on the actual offset firing angle, the offset firing overlap angle, and the state values ​​corresponding to each time period, the state function of the converter is analytically obtained according to the single-sided modulation theory. The dynamic equation unit is used to establish the small-disturbance dynamic equations for the DC voltage and AC current of the converter by combining the state function of the converter and the AC and DC side electrical quantities of the converter shown in each state, including: Based on the state function of the converter, the expressions for the DC voltage and AC current of the converter are determined; The expressions for DC voltage and AC current are linearized to generate small-disturbance dynamic equations for the DC voltage and AC current of the converter. The admittance model unit is used to establish the wideband AC / DC side admittance model corresponding to the converter based on the offset, the state function, and the small disturbance dynamic equation.

6. A device for constructing an admittance model for a power grid phase-commutation converter, characterized in that, Including memory and processor; The memory is used to store programs; The processor is used to execute the program to implement each step of the grid commutator admittance model construction method as described in any one of claims 1-4.

7. A readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements each step of the method for constructing the admittance model of a power grid commutator as described in any one of claims 1-4.

Images