CN116842770A - Method, device and system for quantifying direct-current side dynamic interaction between grid-connected converters - Google Patents
Method, device and system for quantifying direct-current side dynamic interaction between grid-connected converters Download PDFInfo
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Abstract
The invention provides a method, a device and a system for quantifying direct-current side dynamic interaction between a network transformer, wherein the method comprises the following steps: establishing a direct-current voltage control scale small signal model aiming at a system containing N grid-connected converters; based on the established direct-current voltage control scale small signal model, establishing a multi-input multi-output system model expressed by a transfer function matrix; deriving a self-stabilization function and a total-stabilization function based on the established transfer function matrix model of the multi-input multi-output system; based on the derived self-stabilization function and total stabilization function, a dynamic interaction path dividing principle is provided according to the number of equipment and the difference of AC/DC network coupling, and the stabilization function of different paths is calculated. The invention quantifies the influence of dynamic interaction on different paths on the stability of the system by deducing the general formulas of the self-stabilization function and the stabilization function, and reveals the influence of dynamic interaction on the stability of the network-following converter.
Description
Technical Field
The invention relates to the field of novel power system stability analysis, in particular to a method, a device and a system for quantifying direct-current side dynamic interaction between a grid-connected converter.
Background
Small signal stability with multi-converter systems is an important issue facing new energy power systems. The dynamic behavior of such systems is related to the complex dynamic interactions induced by the different grid-connected converters coupled via ac and dc networks. Many researchers have attempted to study this complex dynamic interaction and explain the mechanisms that lead to system instability. Currently, there are mainly several methods for small signal stability analysis of multi-transducer-containing systems:
1. the modal analysis method comprises the following steps: the modal analysis method comprises eigenvalue analysis, participation factor analysis and sensitivity analysis. The method can establish a detailed state space model of the multi-converter system, and based on the detailed state space model, the characteristic value and the small signal stability of the participation factor analysis system are utilized. The gain range of the parameters of the follow-net type converter controller for ensuring the dynamic stability can be obtained by calculating the characteristic value of the system.
2. Impedance analysis method: the impedance analysis method can analyze the influence of the parameters of the inner and outer loop controllers on the VSC impedance characteristics and the system stability.
3. Open loop modal coupling method: the open-loop modal coupling method analyzes oscillation mechanisms caused by interactions between different subsystems in a multi-converter system based on modal analysis.
The prior art has the following defects:
(1) The modal analysis lacks understanding of an instability mechanism, and the existing analysis results cannot explain how dynamic interaction between different heel network converters affects the stability of a system and the distance between the stability and the instability of the system;
(2) The dynamic interaction between the impedance analysis method and the open-loop modal coupling method is not analyzed and quantified when the stability of the multi-converter system is analyzed, whether the dynamic interaction exists between the connected grid-connected converters cannot be confirmed, and whether the dynamic interaction is beneficial to the system stability is difficult to explain.
Disclosure of Invention
The invention provides a method, a device and a system for quantifying direct-current side dynamic interaction between a network-following converter. The method reveals the influence of dynamic interaction with the grid-type converter on stability, and provides a new idea for control parameter design and setting in the multi-terminal flexible direct current transmission system.
A method for quantifying direct-current side dynamic interaction with a network converter comprises the following steps:
step (1): establishing a direct-current voltage control scale small signal model aiming at a system containing N grid-connected converters;
step (2): based on the direct-current voltage control scale small signal model established in the step (1), establishing a multiple-input multiple-output (MIMO) system model expressed by a transfer function matrix;
step (3): deducing a self-stabilization function and a total stabilization function based on a multiple-input multiple-output (MIMO) system transfer function matrix model established in the step (2), wherein the self-stabilization function and the stabilization function can realize interactive layered analysis quantization according to a stabilization action path dividing principle;
step (4): based on the self-stabilization function and the total-stabilization function derived in the step (3), a dynamic interaction path dividing principle is provided according to the number of equipment and the difference of AC/DC network coupling, and the stabilization function of different paths is calculated.
Further, the step (1) specifically includes:
for a system containing N grid-connected converters, each grid-connected converter is provided with an I-U direct-current voltage droop control, vector control and phase-locked controller, a direct-current voltage control scale small-signal model is built based on a motion equation, and three input signals are as follows: input active power dynamics ΔP from DC network ini Output active power dynamics ΔP from an AC network outi Output ac reactive power dynamics Δq from ac network i The method comprises the steps of carrying out a first treatment on the surface of the The three output signals are respectively direct-current voltage dynamic delta U idc Phase dynamics delta theta of ac internal potential i And amplitude dynamics ΔE i Definition:
ΔP in =[ΔP in1 ΔP in2 …ΔP inN ] T
ΔU dc =[ΔU dc1 ΔU dc2 …ΔU dcN ] T
in the formula ΔPin1 ~ΔP inN ，ΔU dc1 ~ΔU dcN Active power and direct current voltage of the 1 st to N th direct current capacitors input by the grid-connected converters are respectively represented;
the power flow in direct and alternating current networks is represented by (1) and (2):
each parameter in the matrix is expressed as:
wherein ,ΔPouti and ΔQi For active and reactive power output of an ac network, Δθ i and ΔEi Is the phase and amplitude of the potential in the AC network, I dci0 U is the current of a direct current network dci0 For the voltage of the DC network, U gi0 Is an infinite power supplyVoltage E i0 Is an alternating-current side internal potential, X fi and Xgi The filter reactance of the follow-net type converter and the reactance of the transmission line are adopted, the subscript i represents the ith follow-net type converter, and 0 represents the initial value under the steady-state condition;
the unbalanced active power at the two ends of the direct current capacitor of the ith converter is written as follows:
by usingReplacement->,/> and />Formula (3) is rewritten as:
wherein ,∆PSi and ∆PEi Representing the unbalanced active power produced by converter i and the other converters; will F Si (s) defining F as a self-stabilizing function Ei (s) defining a stabilization function; f (F) Si (s) reflecting the dynamic characteristics associated with converter i, F Ei (s) reflects the dynamics of all but converter i.
Further, the step (2) specifically includes:
the multiple-input multiple-output system is represented by a transfer function matrix, in a system comprising a plurality of grid-connected converters, the grid-connected converters are directly coupled with a direct current network to transmit active power, and considering an i-th converter in the system, based on a direct current voltage control scale small signal model established in the step (1), the transfer function from reactive power to internal voltage amplitude is represented as:
in an ac network, the active/reactive power flow is expressed as:
and (3) combining the formulas (6) to (7) to obtain the father theta i and ∆Pouti Relationship coupled via an ac network:
wherein
The relationship between the unbalanced active power and the dc voltage from the inverters 1 to N is expressed as:
the internal potential phases of the current transformers 1 to N are expressed as:
the active power output by the converters 1 to N to the ac network is expressed as:
substituting the formula (11) into the formula (12), and expressing the output active power by the direct current voltage and the input active power as:
the unbalanced active power is expressed as:
in combination with formulas (1), (13), (14), the unbalanced active power is expressed as:
the parameters in formula (15) are expressed as:
finally, the small signal model established in the step (1) is converted into a multi-input multi-output system model represented by a transfer function matrix.
Further, the step (3) specifically includes:
the self-stabilization function is the ratio of unbalanced power dynamic to direct-current voltage dynamic generated by the loop current which only flows through the self-stabilization function and the net-type converter after the direct-current voltage of the net-type converter changes;
the stabilizing function refers to the ratio of unbalanced power dynamic to direct current voltage dynamic generated by loop current flowing out of the heel-net type converter and flowing back through other heel-net type converters;
deriving a self-stabilization function and a total-stabilization function based on the multiple-input multiple-output system model which is established in the step (2) and represented by the transfer function matrix, wherein the method comprises the following steps of:
assuming that the current transformer 1 is concerned, since L(s) includes a portion related to the current transformer 1 and a portion related to other current transformers, the feedback path is expressed as:
the dc capacitance dynamics of the converters other than the converter 1 are expressed as:
inverting equation (19) and introducing the result into equation (18), the DC voltage of converter 2~N is ΔU dc1 The substitution is expressed as:
wherein
Substituting equation (20) into (17), the unbalanced power is written as:
according to the definition of the self-stabilization function and the stabilization function in the formula (4), the self-stabilization function is L 11 (s), and the total stabilization function is:
。
further, the step (4) specifically includes:
considering N converter systems, F according to the number of converters involved in the interaction Ei (s) of the N-1 type, for the interaction between the converters 1 and i, the single stability function is written as:
for the interaction between the converters i, j and the converter 1, the pairwise stability function is calculated as:
for interactions involving the most current transformers, the stabilizing function between the heel-net current transformer 2~N and the heel-net current transformer 1 is expressed as:
wherein The rest items are calculated by the same method;
from the different effects of the dc and ac networks, the stabilization function is subdivided into two terms, one being interaction coupled by the dc network only and the other by the dc and ac network at the same time, the first term of L(s), matrix a, reflecting interaction coupled by the dc network only, as seen from the results of (16), and therefore the stabilization function coupled by the dc network only is calculated by:
wherein
The stabilizing function affected by both dc and ac circuits is expressed as:
for a typical system with multiple converters, the different dynamic interaction paths with the grid-connected converters are quantified by explicit expressions of the self-stabilizing function and the stabilizing function.
An apparatus for quantifying dc-side dynamic interactions with a network converter, comprising:
the direct-current voltage control scale small signal model building module is used for building a direct-current voltage control scale small signal model aiming at a system comprising N grid-connected converters;
the MIMO system module is used for establishing a multi-input multi-output system model represented by the transfer function matrix based on the direct-current voltage control scale small signal model;
the self-stabilization function and total-stabilization function deduction module is used for deducting the self-stabilization function and the total-stabilization function based on the multi-input multi-output system model;
the stability causing function calculation module of different paths is used for calculating the stability causing function of different paths based on the derived self-stability causing function and total stability causing function and according to the number of equipment and the different coupling of the AC/DC network, a dynamic interaction path dividing principle is provided.
A system for quantifying dc-side dynamic interactions with a network converter, comprising: a computer readable storage medium and a processor;
the computer-readable storage medium is for storing executable instructions; the processor is used for reading executable instructions stored in the computer readable storage medium and executing the method for dynamically interacting with the direct current side between the grid-type converter in a quantification mode.
The invention firstly establishes a direct-current voltage control scale small signal model aiming at a system containing N heel-net converters, establishes a multiple-input multiple-output (MIMO) system model expressed by a transfer function matrix on the basis, provides concepts of self-stabilization and stabilization function on a direct-current side, derives the self-stabilization function and the total stabilization function, further provides a dynamic interaction path dividing principle according to the number of equipment and the difference of AC/DC network coupling, and calculates the stabilization function of different paths. The method can reveal the influence mechanism of dynamic interaction between the heel-net type converters on stability, and provides a new thought for setting and setting control parameters of the N heel-net type converter systems.
Drawings
FIG. 1 is a system model of a system based on the concept of equations of motion comprising a plurality of heel net converters;
FIG. 2 (a) shows a multi-vodka input multi-output system represented by a transfer function matrix, (b) shows a system small interference model containing dynamic interactive analytical expressions;
in fig. 3, (a) is a frequency response waveform of the self-stabilizing function and the different path-stabilizing function in the vicinity of the oscillation frequency, and (b) is a frequency response waveform of the self-stabilizing function and the total stabilizing function in the vicinity of the oscillation frequency.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The embodiment of the invention discloses a method for quantifying direct-current side dynamic interaction between a network transformer, which comprises the following steps:
step (1): establishing a direct-current voltage control scale small-signal model aiming at a system containing N grid-connected converters
For an N-terminal multi-converter-containing system, each grid-connected converter in the multi-converter-containing system is provided with an I-U direct-current voltage droop control, a vector control and a phase-locked controller, and a direct-current voltage control scale small-signal model can be established based on a motion equation, wherein three input signals are as follows: input active power dynamics ΔP from DC network ini Output active power dynamics ΔP from an AC network outi Output ac reactive power dynamics Δq from ac network i The method comprises the steps of carrying out a first treatment on the surface of the The three output signals are respectively direct-current voltage dynamic delta U idc Phase dynamics delta theta of ac internal potential i And amplitude dynamics ΔE i . The direct-current voltage control scale small signal model is defined as:
ΔP in =[ΔP in1 ΔP in2 …ΔP inN ] T ,
ΔU dc =[ΔU dc1 ΔU dc2 …ΔU dcN ] T ,
in the formula ΔPin1 ~ΔP inN ，ΔU dc1 ~ΔU dcN Active power and DC voltage of the input DC capacitors of the 1 st to N th converters are respectively represented;
the power flow in direct and alternating current networks is represented by (1) and (2):
each parameter in the matrix is expressed as:
wherein ,ΔPouti and ΔQi For active and reactive power output of an ac network, Δθ i and ΔEi Is the phase and amplitude of the potential in the AC network, I dci0 U is the current of a direct current network dci0 For the voltage of the DC network, U gi0 Is infinite power supply voltage E i0 Is an alternating-current side internal potential, X fi and Xgi The filter reactance of the follow-net type converter and the reactance of the transmission line are adopted, the subscript i represents the ith follow-net type converter, and 0 represents the initial value under the steady-state condition;
the unbalanced active power write at the two ends of the direct current capacitor of the ith converter is as follows:
a small interference model, fatu, as shown in FIG. 1 dci The interface between the grid-connected converter i and the direct-current power grid. It is associated with later systems and with heel-net converters and cannot respond freely. Therefore, according to the transfer function reflecting the dynamic characteristics of the converter station, we useReplacement->,/> and />Formula (3) is rewritten as:
wherein ,∆PSi and ∆PEi Representing the unbalanced active power produced by the grid-connected converters i and other grid-connected converters. Will F Si (s) defining F as a self-stabilizing function Ei (s) is defined as the stabilizing function. F (F) Si (s) reflecting the dynamic characteristics associated with the network converter i, F Ei (s) reflects the dynamics of all the heel-net converters except the heel-net converter i.
Step (2): and (3) based on the direct-current voltage control scale small-signal model established in the step (1), establishing a multiple-input multiple-output (MIMO) system model expressed by a transfer function matrix.
The key point of this step is how to build a multiple-input multiple-output (MIMO) system model represented by a transfer function matrix.
The multiple input multiple output system is represented by a transfer function matrix, and in a system comprising a plurality of converters, the network-connected converters are directly coupled with a direct current network to transmit active power. Considering the ith grid-connected converter in the system, as can be seen from the small-signal model of fig. 1, the transfer function from reactive power to internal voltage amplitude can be expressed as:
in an ac network, the active/reactive power flow is expressed as:
and (3) combining the formulas (6) to (7) to obtain the father theta i and ∆Pouti Relationship coupled via an ac network:
wherein
The relationship between the unbalanced active power and the dc voltage from the inverters 1 to N is expressed as:
the internal potential phases of the current transformers 1 to N are expressed as:
the active power output by the converters 1 to N to the ac network is expressed as:
substituting the formula (11) into the formula (12), and expressing the output active power by the direct current voltage and the input active power as:
the unbalanced active power is expressed as:
in combination with formulas (1), (13), (14), the unbalanced active power is expressed as:
the parameters in formula (15) are expressed as:
finally, the system model including the multiple-converter system shown in fig. 1 is converted into a MIMO model represented by a transfer function matrix in fig. 2 (a).
Step (3): deriving a self-stabilizing function and a total-stabilizing function based on the multiple-input multiple-output (MIMO) system transfer function matrix model established in the step (2).
The self-stabilizing function is the ratio of unbalanced power dynamic to direct-current voltage dynamic generated by the loop current which only flows through the self-following net type converter after the direct-current voltage of a certain following net type converter changes, and the stabilizing function is the ratio of unbalanced power dynamic to direct-current voltage dynamic generated by the loop current which flows out of the following net type converter and flows back through other following net type converters.
Based on the model of fig. 2 (a), the self-stabilizing function and the total stabilizing function are derived. Let us assume that the current transformer 1 is concerned. Since L(s) includes a part related to the current transformer 1 and a part related to other current transformers, the feedback path is expressed as:
the dc capacitance dynamics of the converters other than the converter 1 are expressed as:
inverting equation (19) and introducing the result into equation (18), the DC voltage of converter 2~N is ΔU dc1 The substitution is expressed as:
wherein
Substituting equation (20) into (17), the unbalanced power is written as:
according to the definition of the self-stabilization function and the stabilization function in the formula (4), the self-stabilization function is L 11 (s), and the total stabilization function is:
。
step (4): according to the number of equipment and the different coupling of the AC-DC network, a dynamic interaction path dividing principle is provided, and the stability causing function of different paths is calculated.
The ensemble stabilization function may be broken down into different terms according to two principles. Based on principle 1, i.e. the number of stations involved in the interaction, the stabilization function may be decomposed into a single stabilization function, a bi-stabilization function, a tri-stabilization function, etc. Based on principle 2, i.e. the different influence of the direct current and the alternating current network, the term can be broken down into a term coupled only by the direct current network and another term coupled simultaneously by the alternating current and the direct current network.
Considering an N-terminal HVDC system, F according to the number of converters participating in interaction Ei (s) are of the N-1 type. For the interaction between the converters 1 and i, the stability function alone is written as:
for the interaction between the converters i, j and the converter 1, the pairwise stability function is calculated as:
for interactions involving the most current transformers, the stabilizing function between the heel-net current transformer 2~N and the heel-net current transformer 1 is expressed as:
where U= {2,3, …, N }, jlU, Jl/>R1×(N-2), l/>{1,2, …, N-1}. The remaining terms were calculated in the same manner.
The stabilization function is subdivided into two terms according to the different effects of the dc and ac networks. One is an interaction coupled by the direct current network only, and the other is an interaction coupled by both the direct current and alternating current networks. From the results of (16), the first term of L(s), matrix a, reflects interactions coupled only by the dc network. Thus, the stabilizing function coupled only by the dc network is calculated by:
wherein
The stabilizing function affected by both dc and ac circuits is expressed as:
the small interference model containing quantification of inter-equipment dynamic interaction resolution is represented in fig. 2 (b). Thus, for a typical system comprising multiple converters, the different dynamic interaction paths with the net-type converters are quantified by explicit expressions of the self-stabilizing function and the stabilizing function.
The experiment in fig. 3 demonstrates the effectiveness of the proposed method of the present invention. In fig. 3 (a) the steady state coefficient of the converter station 3 to the converter station 1 coupled via the dc networkStability coefficient of converter station 1 coupled with converter station 3-4 via AC/DC network>Has maximum two positive values, which is beneficial for system stability, while the self-stabilizing coefficient of the converter station 1Stability coefficient of converter station 1 coupled with converter station 2-4 via AC/DC network>Having two largest positive values is the main cause of destabilization of the system. Illustrated in FIG. 3 (b), at oscillation frequency ω d1 At=53.1 rad/s, the sum Re [ F ] of the self-stabilizing function and the total stabilizing function E1 (jω)+F S1 (jω)]> 0, system instability.
The embodiment of the invention also correspondingly provides a device for quantifying the dynamic interaction with the DC side of the network type converter, which comprises the following components:
the direct-current voltage control scale small signal model building module is used for building a direct-current voltage control scale small signal model aiming at a system comprising N grid-connected converters;
the MIMO system module is used for establishing a multi-input multi-output system model represented by the transfer function matrix based on the direct-current voltage control scale small signal model;
the self-stabilization function and total-stabilization function deduction module is used for deducting the self-stabilization function and the total-stabilization function based on the multi-input multi-output system model;
the stability causing function calculation module of different paths is used for calculating the stability causing function of different paths based on the derived self-stability causing function and total stability causing function and according to the number of equipment and the different coupling of the AC/DC network, a dynamic interaction path dividing principle is provided.
The embodiment of the invention also correspondingly provides a system for quantifying the dynamic interaction of the direct current side between the network transformer and the network transformer, which comprises the following components: a computer readable storage medium and a processor;
the computer-readable storage medium is for storing executable instructions; the processor is used for reading executable instructions stored in the computer readable storage medium and executing the method for dynamically interacting with the direct current side between the grid-type converter in a quantification mode.
The foregoing is merely illustrative embodiments of the present invention, and the present invention is not limited thereto, and any changes or substitutions that may be easily contemplated by those skilled in the art within the scope of the present invention should be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (7)
1. A method for quantifying direct current side dynamic interactions with a network converter, comprising the steps of:
step (1): establishing a direct-current voltage control scale small signal model aiming at a system containing N grid-connected transformers;
step (2): based on the direct-current voltage control scale small signal model established in the step (1), establishing a multi-input multi-output system model expressed by a transfer function matrix;
step (3): deducing a self-stabilization function and a total-stabilization function based on the transfer function matrix model of the multi-input multi-output system established in the step (2);
step (4): based on the self-stabilization function and the total-stabilization function derived in the step (3), a dynamic interaction path dividing principle is provided according to the number of equipment and the difference of AC/DC network coupling, and the stabilization function of different paths is calculated.
2. A method of quantifying dc-side dynamic interactions with a grid-connected converter as recited in claim 1, wherein: the step (1) specifically comprises the following steps:
for a system containing N grid-connected converters, each grid-connected converter is provided with an I-U direct-current voltage droop control, vector control and phase-locked controller, a direct-current voltage control scale small-signal model is built based on a motion equation, and three input signals are as follows: input active power dynamics ΔP from DC network ini Output active power dynamics ΔP from an AC network outi Output ac reactive power dynamics Δq from ac network i The method comprises the steps of carrying out a first treatment on the surface of the The three output signals are respectively direct-current voltage dynamic delta U idc Phase dynamics delta theta of ac internal potential i And amplitude dynamics ΔE i Definition:
ΔP in =[ΔP in1 ΔP in2 …ΔP inN ] T
ΔU dc =[ΔU dc1 ΔU dc2 …ΔU dcN ] T
in the formula ΔPin1 ~ΔP inN ，ΔU dc1 ~ΔU dcN Active power and direct current voltage of the 1 st to N th direct current capacitors input by the grid-connected converters are respectively represented;
the power flow in direct and alternating current networks is represented by (1) and (2):
；
each parameter in the matrix is expressed as:
；
wherein ,ΔPouti and ΔQi For active and reactive power output of an ac network, Δθ i and ΔEi Is the phase and amplitude of the potential in the AC network, I dci0 U is the current of a direct current network dci0 For the voltage of the DC network, U gi0 Is infinite power supply voltage E i0 Is an alternating-current side internal potential, X fi and Xgi The filter reactance of the follow-net type converter and the reactance of the transmission line are adopted, the subscript i represents the ith follow-net type converter, and 0 represents the initial value under the steady-state condition;
the unbalanced active power at the two ends of the direct current capacitor of the ith converter is written as follows:
；
by usingReplacement->,/> and />Formula (3) is rewritten as:
；
wherein , and />Representing unbalanced active power produced by converter i and other convertersA power; will F Si (s) defining F as a self-stabilizing function Ei (s) defining a stabilization function; f (F) Si (s) reflecting the dynamic characteristics associated with converter i, F Ei (s) reflects the dynamics of all but converter i.
3. A method of quantifying dc-side dynamic interactions with a grid-connected converter as recited in claim 2, wherein: the step (2) specifically comprises:
the multiple-input multiple-output system is represented by a transfer function matrix, in a system comprising a plurality of grid-connected converters, the grid-connected converters are directly coupled with a direct current network to transmit active power, and considering an i-th converter in the system, based on a direct current voltage control scale small signal model established in the step (1), the transfer function from reactive power to internal voltage amplitude is represented as:
；
in an ac network, the active/reactive power flow is expressed as:
；
derived by combining equations (6) to (7) and />Relationship coupled via an ac network:
；
wherein
；
The relationship between the unbalanced active power and the dc voltage from the inverters 1 to N is expressed as:
；
the internal potential phases of the current transformers 1 to N are expressed as:
；
the active power output by the converters 1 to N to the ac network is expressed as:
；
substituting the formula (11) into the formula (12), and expressing the output active power by the direct current voltage and the input active power as:
；
the unbalanced active power is expressed as:
；
in combination with formulas (1), (13), (14), the unbalanced active power is expressed as:
；
the parameters in formula (15) are expressed as:
；
finally, the small signal model established in the step (1) is converted into a multi-input multi-output system model represented by a transfer function matrix.
4. A method of quantifying dc-side dynamic interactions with a grid-connected converter as recited in claim 3, wherein: the step (3) specifically comprises:
the self-stabilization function is the ratio of unbalanced power dynamic to direct-current voltage dynamic generated by the loop current which only flows through the self-stabilization function and the net-type converter after the direct-current voltage of the net-type converter changes;
the stabilizing function refers to the ratio of unbalanced power dynamic to direct current voltage dynamic generated by loop current flowing out of the heel-net type converter and flowing back through other heel-net type converters;
deriving a self-stabilization function and a total-stabilization function based on the multiple-input multiple-output system model which is established in the step (2) and represented by the transfer function matrix, wherein the method comprises the following steps of:
assuming that the current transformer 1 is concerned, since L(s) includes a portion related to the current transformer 1 and a portion related to other current transformers, the feedback path is expressed as:
；
the dc capacitance dynamics of the converters other than the converter 1 are expressed as:
；
inverting equation (19) and introducing the result into equation (18), the DC voltage of converter 2~N is ΔU dc1 The substitution is expressed as:
；
wherein
；
Substituting equation (20) into (17), the unbalanced power is written as:
；
according to the definition of the self-stabilization function and the stabilization function in the formula (4), the self-stabilization function is L 11 (s), and the total stabilization function is:
。
5. a method of quantifying dc-side dynamic interactions with a grid-connected converter as recited in claim 4, wherein: the step (4) specifically comprises:
considering N converter systems, F according to the number of converters involved in the interaction Ei (s) of the N-1 type, for the interaction between the converters 1 and i, the single stability function is written as:
；
for the interaction between the converters i, j and the converter 1, the pairwise stability function is calculated as:
；
for interactions involving the most current transformers, the stabilizing function between the heel-net current transformer 2~N and the heel-net current transformer 1 is expressed as:
；
wherein The rest items are calculated by the same method;
from the different effects of the dc and ac networks, the stabilization function is subdivided into two terms, one being interaction coupled by the dc network only and the other by the dc and ac network at the same time, the first term of L(s), matrix a, reflecting interaction coupled by the dc network only, as seen from the results of (16), and therefore the stabilization function coupled by the dc network only is calculated by:
；
wherein
；
The stabilizing function affected by both dc and ac circuits is expressed as:
；
for a typical system with multiple converters, the different dynamic interaction paths with the grid-connected converters are quantified by explicit expressions of the self-stabilizing function and the stabilizing function.
6. A device for quantifying dc-side dynamic interactions with a network converter, comprising:
the direct-current voltage control scale small signal model building module is used for building a direct-current voltage control scale small signal model aiming at a system comprising N grid-connected converters;
the MIMO system module is used for establishing a multi-input multi-output system model represented by the transfer function matrix based on the direct-current voltage control scale small signal model;
the self-stabilization function and total-stabilization function deduction module is used for deducting the self-stabilization function and the total-stabilization function based on the multi-input multi-output system model;
the stability causing function calculation module of different paths is used for calculating the stability causing function of different paths based on the derived self-stability causing function and total stability causing function and according to the number of equipment and the different coupling of the AC/DC network, a dynamic interaction path dividing principle is provided.
7. A system for quantifying dc-side dynamic interactions with a network converter, comprising: a computer readable storage medium and a processor;
the computer-readable storage medium is for storing executable instructions; the processor is configured to read executable instructions stored in the computer readable storage medium and execute the method of quantifying dc-side dynamic interactions with a grid-type converter according to any one of claims 1-5.
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