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CN114154446A - DC power system dynamic characteristic analysis method based on mixed time scale modeling - Google Patents

DC power system dynamic characteristic analysis method based on mixed time scale modeling Download PDF

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CN114154446A
CN114154446A CN202111346731.8A CN202111346731A CN114154446A CN 114154446 A CN114154446 A CN 114154446A CN 202111346731 A CN202111346731 A CN 202111346731A CN 114154446 A CN114154446 A CN 114154446A
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陈鹏伟
卢亮
刘念
孙雅旻
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Nanjing University of Aeronautics and Astronautics
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Abstract

The embodiment of the invention discloses a dynamic characteristic analysis method of a direct current power system based on mixed time scale modeling, relates to the technical field of power electronic systems of direct current power distribution, and can improve the high efficiency of digital electromagnetic transient analysis. The invention comprises the following steps: establishing an EMT subsystem and a DP subsystem of a direct current power system; the established EMT subsystem is led into the FPGA1, and the established DP subsystem is led into the FPGA 2; establishing an interface calculation module according to external characteristics of the EMT subsystem and the DP subsystem, and deploying the interface calculation module on the FPGA 3; after initialization, the EMT subsystem performs n times of single-step analysis and the DP subsystem performs one time of single-step analysis until the interaction time is reached; and outputting the analysis result to the terminal equipment.

Description

DC power system dynamic characteristic analysis method based on mixed time scale modeling
Technical Field
The invention relates to the technical field of power electronic systems of direct-current power distribution, in particular to a dynamic characteristic analysis method of a direct-current power system based on mixed time scale modeling.
Background
As an important carrier integrating consumption, high-efficiency access of electric vehicles, transformation and capacity increase of power distribution networks and comprehensive energy systems, direct current power distribution becomes one of the development directions of future power grids and even energy Internet. However, a direct current power system accepts an alternating current main network, a low-voltage distribution network, a wind power, photovoltaic and other new energy power generation systems, both source and load ends are highly power-electronized, and the power-electronic converter and the control protection strategy are very complex to form along with the improvement of capacity and power level and the increase of the number of power electronic devices.
As an important means for analyzing and verifying the safety, stability and power supply quality characteristics of the multi-terminal direct current power system, the transient analysis of the power system is not limited by the scale and structural complexity of the system. But the increase in system scale and the extension of the device switching frequency will make its contradiction in electromagnetic transient simulation efficiency more prominent (usually it is necessary to set the integration step size to 1/10 or even smaller of the switching period). If the research on the behavior and the static characteristics is carried out step by step based on a full-system detailed model and a small-scale product, the efficiency of the digital electromagnetic transient analysis is difficult to guarantee. Therefore, how to simultaneously improve the efficiency of the digital electromagnetic transient analysis becomes a problem that needs to be studied.
Disclosure of Invention
The embodiment of the invention provides a method for analyzing the dynamic characteristics of a direct-current power system based on mixed time scale modeling, which can improve the high efficiency and the accuracy of digital electromagnetic transient analysis.
In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:
s1, establishing an EMT subsystem and a DP subsystem of the direct current power system;
s2, importing the built EMT subsystem into an FPGA1, and importing the built DP subsystem into an FPGA 2;
s3, establishing an interface calculation module according to the external characteristics of the EMT subsystem and the DP subsystem, and deploying the interface calculation module on an FPGA3, wherein the FPGA3 is used for data interaction of the EMT calculation module and the DP calculation module;
s4, after initialization, the EMT subsystem carries out single-step analysis for n times and the DP subsystem carries out single-step analysis for one time until the interaction time is reached;
and S5, outputting the analysis result to the terminal equipment.
The scheme of the embodiment can be applied to a platform for Dynamic Phasor (DP) -electromagnetic transient (EMT) hybrid simulation of a direct current power system, and the non-concerned part of the direct current power system to be simulated is processed by adopting dynamic phasor modeling, so that the high efficiency of simulation is ensured; processing the concerned part of the DC power system to be simulated by adopting electromagnetic transient modeling to ensure the simulation accuracy; interface data interaction and series-parallel time sequence hybrid simulation are realized by utilizing the multi-block FPGA, and the high efficiency of simulation is ensured. A dynamic phasor-electromagnetic transient hybrid simulation heterogeneous platform is built, and the simulation precision and speed of the direct current power system are balanced. The dynamic phasor-electromagnetic transient hybrid simulation has small hardware limitation on simulation equipment, and can realize simulation on a large-scale alternating current and direct current system; the modification of the hybrid simulation interface mode, and the modification and the upgrade of the hybrid simulation can be flexibly realized.
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In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIGS. 1 and 2 are schematic diagrams of embodiments provided by embodiments of the present invention;
fig. 3 is a schematic diagram illustrating a division manner of a hybrid simulation subsystem of a dc power system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating the main logic flow of a hybrid simulation algorithm according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a method flow provided by the embodiment of the invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention. As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The embodiment of the invention provides a method for analyzing dynamic characteristics of a direct-current power system based on mixed time scale modeling, which comprises the following steps of:
and S1, establishing an EMT subsystem and a DP subsystem of the direct current power system.
And S2, importing the built EMT subsystem into the FPGA1, and importing the built DP subsystem into the FPGA 2.
The FPGA2 can also be understood as a cluster composed of multiple FPGAs, and in practical applications, the number of EMT subsystems may be 1, but the number of DP subsystems may be multiple, and the FPGA2 may include multiple FPGAs.
And S3, establishing an interface calculation module according to the external characteristics of the EMT subsystem and the DP subsystem, and deploying the interface calculation module on an FPGA3, wherein the FPGA3 is used for data interaction of the EMT calculation module and the DP calculation module.
Logic for parallel-connection simulation time sequence control can be further introduced into the FPGA3, so that the simulation time sequence control logic is used for selecting serial or parallel processing in subsequent processing, specifically, the logic for simulation time sequence control can be loaded into an interface computing module deployed on the FPGA3, and the interface computing module selects serial time sequence simulation or parallel time sequence simulation in subsequent processing. Therefore, the FPGA3 is specifically used for simulating timing selection and data interaction of the EMT calculation module and the DP calculation module.
And S4, after initialization, performing single-step analysis for n times by the EMT subsystem and performing single-step analysis for one time by the DP subsystem until the interaction time is reached.
And S5, outputting the analysis result to the terminal equipment.
Wherein, in S1, the method includes: establishing state equations of an EMT subsystem and a DP subsystem, and operating the DP subsystem by using an FPGA2, wherein the state equation of the EMT subsystem is as follows:
Figure BDA0003354437010000041
wherein r isDFor the real-time amount of interaction of the DP sub-system,
Figure BDA0003354437010000042
representing the differential term of the EMT subsystem state variable, AERepresenting the EMT subsystem state variable matrix, xERepresenting EMT subsystem state variables, BERepresenting the EMT subsystem control variable matrix, u representing the EMT subsystem control variables, CE-DThe interaction quantity matrix of the EMT subsystem is represented, the EMT subsystem is represented by E, the DP subsystem is represented by D, and the state equation of the DP subsystem is as follows:
Figure BDA0003354437010000043
rEk represents the order of the dynamic phasor for the real-time interaction quantity of the EMT subsystem,
Figure BDA0003354437010000044
representing the DP subsystem state variable differential term, xDRepresenting DP subsystem state variables, j representing units of imaginary numbers, ω s2 pi/T, T denotes the fundamental period, ADRepresenting the DP subsystem State variable matrix, BDRepresenting DP subsystem control variable matrix, uDRepresenting DP subsystem control variables, operators<x>kRepresenting the k-order dynamic phasors for the respective variables.
In practical application, a state equation of a subsystem needs to be established, and the simulation of the subsystem is realized by using the FPGA:
Figure BDA0003354437010000051
in the formula: r isDReal-time interaction volume for DP subsystem
And establishing a state equation of the DP subsystem, wherein when the DP subsystem adopts dynamic phasor modeling, a state equation (2) described by an instantaneous value differential equation is converted into an equation (3)
Figure BDA0003354437010000052
In the formula: r isEFor real-time interaction volume of the DP subsystem:
Figure BDA0003354437010000053
in the formula: omega s2 pi/T, T being the fundamental period, operator<x>kK-order dynamic phasors representing corresponding variables are defined and solved in a manner
Figure BDA0003354437010000054
In the formula: the superscripts "R" and "I" denote the real and imaginary parts, respectively.
Specifically, the dynamic process of the DP subsystem needs to be split into a real part and an imaginary part. In practical application, a computer can not calculate a differential equation containing complex numbers, so that the differential equation can be solved only by expanding the differential equation into a real part equation and an imaginary part equation, and all the equations<x>kThis form is a complex number which can be expressed as
Figure BDA0003354437010000055
Due to the complex characteristic of the dynamic phasor, the real part and the imaginary part of the dynamic process of the DP subsystem represented by the formula (4) are split, and the real part and the imaginary part of the dynamic process can be obtained
Figure BDA0003354437010000056
R represents a real part, I represents an imaginary part,
Figure BDA0003354437010000057
representing the real part matrix of the state variables of the DP subsystem,
Figure BDA0003354437010000058
representing the imaginary matrix of the state variables of the DP subsystem,
Figure BDA0003354437010000059
representing the real part matrix of the control variable of the DP subsystem,
Figure BDA00033544370100000510
representing the imaginary matrix of the control variables of the DP subsystem,
Figure BDA00033544370100000511
a matrix representing the real part of the interaction quantity of the DP subsystem,
Figure BDA00033544370100000512
representing the imaginary matrix of the DP subsystem interaction quantities,
Figure BDA0003354437010000061
representing the real part of the real-time interaction quantity of the EMT subsystem,
Figure BDA0003354437010000062
represents the real-time interaction quantity imaginary part of the EMT subsystem,
Figure BDA0003354437010000063
representing the real part of the state variable of the DP subsystem,
Figure BDA0003354437010000064
representing the imaginary part of the state variable of the DP subsystem.
In this embodiment, in the process of performing data interaction between the EMT calculation module and the DP calculation module by using the FPGA3, the interface mechanism adopted includes:
and extracting dynamic phasor values from the interaction quantity instantaneous values output by the EMT subsystem.
And generating an interaction quantity instantaneous value by using the interaction quantity in the form of the dynamic phasor output by the DP subsystem.
And the controlled voltage source and the controlled current source are used as interface circuits during single-step solution of the EMT subsystem and the DP subsystem, and the interaction quantity is used as the amplitude of the controlled source.
Because the direct current side characteristics can be roughly divided into a bus voltage control type and a bus current control type, a controlled voltage source and a controlled current source are respectively used as interface circuits during single-step solving of the two types of subsystems, and the interaction quantity is the amplitude value of the controlled source. And the link (II) is used for extracting dynamic phasor values from the EMT subsystem interaction quantity instantaneous values, and the link (III) is used for generating instantaneous values from the DP subsystem interaction quantity in the form of dynamic phasors.
Further, an interface calculation module is built. And determining an interface scheme according to the external characteristics of the EMT subsystem and the DP subsystem, and realizing simulation time sequence selection and data interaction of the EMT calculation module and the DP calculation module by using the FPGA 3. For subsystems formed by a converter station, a load converter and the like, the direct-current side characteristics of the subsystems can be roughly divided into a bus voltage control type and a bus current control type, so that a controlled voltage source and a controlled current source are respectively used as interface circuits for single-step solution of the two subsystems, and the interaction quantity is the amplitude value of the controlled source. Fig. 2 shows an interface mechanism schematic, wherein links (i) and (iii) are the EMT and DP subsystems, link (ii) is used for extracting dynamic phasor values from the instantaneous values of the interaction quantities of the EMT subsystem, and link (iv) is used for generating instantaneous values from the interaction quantities of the DP subsystem in the form of dynamic phasor.
In this embodiment, in step S4, the initialization process includes:
and initializing an EMT calculation module of the EMT subsystem, a DP calculation module of the DP subsystem and an interface calculation module.
The interface computing module is used as a bridge for interaction of the two subsystems. The initialization process includes: the time of the three modules is synchronous and the initial time is t ═ t0The simulation system comprises an EMT subsystem simulation step length delta T, a DP subsystem simulation step length delta T, a total simulation duration T, an EMT calculation module and a DP calculation module system parameter, wherein T0 indicates that the initial time is generally 0, and delta T indicates the EMT subsystem simulation step length. Delta t and n are selected according to specific practice, the delta t is generally selected to be 1-10 microseconds, and n is 10-100; the EMT calculation module and the DP calculation module include all parameters in a state quantity matrix and a control quantity matrix when the DP subsystem and the EMT subsystem are established.
In this embodiment, the hybrid simulation includes two types, i.e., a serial timing simulation and a parallel timing simulation, as shown in fig. 2, for the serial timing simulation, in step S4, the DP subsystem performs a single-step length analysis at a time, including:
at time t1, the interaction variables in the form of dynamic phasors output by the DP subsystem are generated via an interface into a sequence of instantaneous values and transferred to the EMT subsystem. The "interface" here may also be referred to as "hybrid simulation interface" and is implemented on a hardware level as an interface circuit, such as a controlled voltage source or a current source as shown in fig. 1, where the left side in fig. 1 is two EMT subsystems and interface circuit forms, and the right side is the corresponding oneTwo DP subsystems. The EMT subsystem interface may be a controlled voltage source or current source, while the corresponding DP subsystem may be a controlled current source or controlled voltage source; wherein, the single-step solution means that: calculating a simulation step length; the interaction volume refers to: r in establishing EMT and DP subsystemsE、rDThe value of "interaction amount" is the value of "controlled source amplitude". And the EMT subsystem reads the interaction quantity from the instantaneous value sequence, sets an interface circuit controlled source, and then analyzes according to the electromagnetic transient step until the time t 2. As shown in fig. 2, at each interaction time represented by time T1, there are many times of simulation, and a simulation step Δ T of the DP subsystem is between T1 and T2. And updating the instantaneous value sequence according to an analysis result obtained by the EMT subsystem, extracting a dynamic phasor value of the interaction quantity through an interface calculation module, and transmitting the dynamic phasor value to the DP subsystem, wherein the interface calculation module is used for loading an interface mechanism shown in figure 1 so as to realize the interaction between the DP subsystem and the EMT subsystem. And the DP subsystem is executed to the time t2, and if the interaction interval is consistent with the simulation step length of the DP subsystem, only one iteration is carried out. When entering the next interactive interval, the steps of fig. 2a are executed. Wherein the interaction interval is: the time of each time the interface calculation module transfers the interaction amount is generally consistent with the simulation step length of the DP subsystem, and the time of each time the interface calculation module transfers the interaction amount is not smaller than the simulation step length of the DP subsystem in practical application.
Specifically, the method, when a serial timing processing mode is adopted, includes:
step 11: at time t1, DP subsystem interaction vector dynamic phasor value<rD>kGeneration of a sequence of momentary values r via a hybrid simulation interfaceD，n＝{rD，n(t)，…rD，n(t + (m-1) delta t) } and then transmitting the data to the EMT subsystem;
step 12: EMT subsystem from interaction quantity instantaneous value sequence rDSequentially reading the interaction quantity, setting an interface circuit controlled source, and executing simulation steps m according to the electromagnetic transient step length delta t until t 2;
step 13: by the EMT subsystem (t)1，t2]Simulation result, update [ t2-T，t2]The time interval interaction quantity instantaneous value sequence is used for extracting the interaction quantity dynamic phasor value through the hybrid simulation interface<rE>kAnd passed to the DP sub-system for (t)1，t2]Simulating time;
step 14: and the DP subsystem is executed to the time T2 by the simulation step length delta T, and if the interaction interval is consistent with the simulation step length of the DP subsystem, only one iteration is carried out.
When entering the next interactive interval, the steps (c) - (c) in fig. 2a) are executed, which are the same as the steps (c) - (c) in fig. 2 a).
For the parallel timing simulation, in step S4, the EMT subsystem performs n single-step analyses, including: at time t1, the interaction quantity in the form of dynamic phasor output by the DP subsystem is generated into a sequence of instantaneous values by the hybrid simulation interface, and then transmitted to the EMT subsystem. The EMT subsystem utilizes a sequence of instantaneous values (expressed in the form: [ t ]1-T,t1]) And extracting the dynamic phasor value of the interaction vector through an interface and transmitting the dynamic phasor value to the DP subsystem. When the interaction is carried out, the two subsystems need to transmit the interaction quantity to the interface calculation module to generate a corresponding form, and then the next stage of simulation is completed, so that the simulation can be considered. The two processes of generating an instantaneous value sequence by the interactive quantity in the form of the dynamic phasor output by the DP subsystem through a hybrid simulation interface and then transmitting the instantaneous value sequence to the EMT subsystem, and extracting the dynamic phasor value of the interactive quantity through the interface and transmitting the dynamic phasor value to the DP subsystem by the EMT subsystem are carried out simultaneously.
Specifically, the parallel time-series processing method includes:
step 21: at time t1, DP subsystem interaction vector dynamic phasor value<rD>kGeneration of a sequence of momentary values r via a hybrid simulation interfaceD,n＝{rD,n(t),…rD,n(t + (m-1) delta t) } and then transmitting the data to the EMT subsystem; at the same time, the EMT subsystem utilizes [ t ]1-T,t1]Time interval interaction quantity instantaneous value sequence, and interaction quantity dynamic phasor value is extracted through interface<rE>kAnd transmits to DP subsystem;
step 22: the EMT subsystem and the DP subsystem are respectively executed in step size delta T and delta T simulation until the time T2, and the DP subsystem updates the interaction quantity instantaneous value sequence to T2-T,t2]。
The steps (c) - (c) in fig. 2b) correspond to the next interaction interval, and the execution process is the same as the steps (c) - (c) in fig. 2b), and is not repeated.
Need to explain: the serial timing simulation is described by taking an EMT subsystem leading a DP subsystem as an example, and may be actually constructed in a manner that the DP subsystem leads the EMT subsystem. Due to the inconsistency of the time attributes of the interaction quantities, although serial and parallel time sequence simulation are independently solved by each subsystem, certain convergence difference still exists. In general, serial timing simulation has relatively high convergence and low hardware requirements for simulation platforms, but is far less computationally efficient than parallel timing simulation.
In practical application of this embodiment, the following implementation processes may also be adopted, including:
step 101: and (4) subsystem division. The dc power system is divided into a detailed electromagnetic transient modeling subsystem (EMT subsystem) and a simplified dynamic phasor modeling subsystem (DP subsystem) according to the degree of attention of the object.
Step 102: and (5) building an EMT calculation module. And importing the established EMT subsystem mathematical model program into the FPGA 1.
Step 103: and (5) building a DP calculation module. And importing the established DP subsystem mathematical model program into the FPGA cluster 2.
Step 104: and (5) building an interface calculation module. And determining an interface scheme according to the external characteristics of the EMT subsystem and the DP subsystem, and realizing simulation time sequence selection and data interaction of the EMT calculation module and the DP calculation module by using the FPGA 3.
Step 105: and (5) module initialization. The EMT calculation module, the DP calculation module and the interface calculation module are initialized, and the initialization comprises the initialization of the initial time t equal to t0Determining simulation total time length T, simulation time sequence (serial time sequence simulation and parallel time sequence simulation), EMT subsystem simulation step length delta T, DP subsystem simulation step length delta T ═ n delta T, EMT and DP calculate module system parameters.
Step 106: and completing the single-step simulation of the EMT subsystem for n times and the single-step simulation of the DP subsystem for one time. When the interaction time is reached, the interface calculation module finishes the extraction, transformation and transmission of the interaction data of the DP calculation module and the EMT calculation module.
Step 107: and judging whether the simulation is finished or not, if T is more than or equal to T, finishing the simulation, outputting a result, and otherwise, returning to the step 106.
If the simulation is further described with reference to fig. 3 and 4, the invention utilizes the FPGA to build the EMT calculation module, the DP calculation module and the interface calculation module to form a dynamic phasor-electromagnetic transient hybrid simulation platform, so as to complete the hybrid simulation of the direct current power system, and balance the simulation efficiency and accuracy. The concrete implementation is as follows:
step 201: taking the three-terminal VSC dc power system shown in fig. 3 as an example, the subsystem 1 formed by the converter station 1 and the dc network is an EMT subsystem, and the converter stations 2 and 3 including the ac equivalent circuit are DP subsystems.
Step 202: and (5) building an EMT calculation module. And importing the established EMT subsystem mathematical model program into the FPGA 1.
Step 203: and (5) building a DP calculation module. Taking the DP subsystem main circuit containing VSC converter station shown in fig. 1 as an example, when a switching function is introduced to describe the switching process, the general expression of the DP subsystem main circuit dynamic phasor model is
Figure BDA0003354437010000111
In the formula: p ∈ { a, b, c } denotes three phases, uspFor an AC side equivalent power supply ispFor each phase current, u, of an AC side equivalent power supplydcIs the DC side capacitor voltage idcFor the output of current, S, on the DC sidea＝2sa/3-sb/3-sc/3，Sb＝2tb/3-sa/3-sc/3，Sc＝2sc/3-sa/3-sb/3，spAs a three-phase bridge arm switching function.
When only the dominant component of the dc power system is considered, the ac-side state quantity is modeled by 1, 5, and 7-order dynamic phasors, the dc-side state quantity is modeled by 0 and 6-order dynamic phasors, and equation (6) can be decomposed as:
Figure BDA0003354437010000112
wherein for multivariable formation
Figure BDA0003354437010000121
Can be composed of<xy>kExpansion of acquisition by the nature of dynamic phasor convolution, i.e.
Figure BDA0003354437010000122
In the formula (I), the compound is shown in the specification,
Figure BDA0003354437010000123
and importing the established DP subsystem mathematical model program into the FPGA cluster 2.
Step 204: and (3) building an interface calculation module, wherein the constant voltage station shown in the figure 3 is of a bus voltage control type, and an interface of a controlled voltage source is selected.
Step 205: inputting parameters of a system to be simulated, and setting an initial simulation time T equal to 0, a simulation step length delta T of an EMT calculation module, a simulation step length delta T of a DP calculation module and a total simulation duration T.
Step 206: initializing interface module parameters, and determining that the system selects serial time sequence simulation or parallel time sequence simulation.
Step 207: the simulation time updates T to T + Δ T.
Step 208: the EMT calculation module completes n times of single-step simulation. After each simulation, data interaction is not carried out, the dynamic phasor interaction value adopts the value of the first single-step length simulation, and the initial values of other state quantities need to be updated after each simulation.
Step 209: and the DP calculation module completes one-time single-step simulation.
Step 2010: and judging whether the simulation is finished, if T is less than T, performing step 2011, and otherwise, performing step 2014.
Step 2011: and the EMT calculation module and the DP calculation module transmit the interaction magnitude value at the time t to the interface module.
Step 2012: the interface calculation module analyzes the interactive data transmitted by the EMT subsystem, generates an instantaneous value and transmits the instantaneous value to the DP calculation module; and analyzing the interactive data transmitted by the DP subsystem, extracting a dynamic phasor value, and transmitting the dynamic phasor value to the EMT calculation module.
Step 2013: : after the states and control matrices of the EMT calculation module and the DP calculation module are updated, the process returns to step 206.
Step 2014: and outputting a result, and finishing the simulation.
The scheme of the embodiment can be applied to a platform for Dynamic Phasor (DP) -electromagnetic transient (EMT) hybrid simulation of a direct current power system, and the non-concerned part of the direct current power system to be simulated is processed by adopting dynamic phasor modeling, so that the high efficiency of simulation is ensured; processing the concerned part of the DC power system to be simulated by adopting electromagnetic transient modeling processing, and ensuring the simulation accuracy; interface data interaction and series-parallel time sequence hybrid simulation are realized by utilizing the multi-block FPGA, and the high efficiency of simulation is ensured. The existing electromagnetic transient simulation platform can be utilized to build a dynamic phasor-electromagnetic transient hybrid simulation heterogeneous platform, and the simulation precision and speed of the power system are balanced. The dynamic phasor-electromagnetic transient hybrid simulation has small hardware limitation on simulation equipment, and can realize simulation on a large-scale alternating current and direct current system; the modification of the hybrid simulation interface mode, and the modification and the upgrade of the hybrid simulation can be flexibly realized.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, that is, each embodiment is described with emphasis on being different from the other embodiments. In particular, for the apparatus embodiment, since it is substantially similar to the method embodiment, it is relatively simple to describe, and reference may be made to some descriptions of the method embodiment for relevant points. The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (9)

1. A method for analyzing dynamic characteristics of a direct current power system based on mixed time scale modeling is characterized by comprising the following steps:
s1, establishing an EMT subsystem and a DP subsystem of the direct current power system;
s2, importing the built EMT subsystem into an FPGA1, and importing the built DP subsystem into an FPGA 2;
s3, establishing an interface calculation module according to the external characteristics of the EMT subsystem and the DP subsystem, and deploying the interface calculation module on an FPGA3, wherein the FPGA3 is used for data interaction of the EMT calculation module and the DP calculation module;
s4, after initialization, the EMT subsystem carries out single-step analysis for n times and the DP subsystem carries out single-step analysis for one time until the interaction time is reached;
and S5, outputting the analysis result to the terminal equipment.
2. The hybrid time scale modeling based direct current power system dynamic behavior analysis method of claim 1, wherein the state equation of the EMT subsystem is expressed as:
Figure FDA0003354435000000011
wherein r isDFor the real-time amount of interaction of the DP sub-system,
Figure FDA0003354435000000012
representing the differential term of the EMT subsystem state variable, AERepresenting the EMT subsystem state variable matrix, xERepresenting EMT subsystem state variables, BERepresenting the EMT subsystem control variable matrix, u representing the EMT subsystem control variables, CE-DRepresenting the interaction quantity matrix of the EMT subsystem, subscript E representing the EMT subsystem, and subscript DRepresents a DP sub-system;
the state equation for the DP subsystem is expressed as:
Figure FDA0003354435000000013
rEk represents the order of the dynamic phasor for the real-time interaction quantity of the EMT subsystem,
Figure FDA0003354435000000014
representing the DP subsystem state variable differential term, xDRepresenting DP subsystem state variables, j representing units of imaginary numbers, ωs2 pi/T, T denotes the fundamental period, ADRepresenting the DP subsystem State variable matrix, BDRepresenting DP subsystem control variable matrix, uDRepresenting DP subsystem control variables, operators<x>kRepresenting the k-order dynamic phasors for the respective variables.
3. The hybrid time scale modeling based dc power system dynamics analysis method of claim 2, further comprising:
splitting the dynamic process of the DP subsystem into a real part and an imaginary part, wherein the real part and the imaginary part are as follows:
Figure FDA0003354435000000021
r represents a real part, I represents an imaginary part,
Figure FDA0003354435000000022
representing the real part matrix of the state variables of the DP subsystem,
Figure FDA0003354435000000023
representing the imaginary matrix of the state variables of the DP subsystem,
Figure FDA0003354435000000024
representing the real part matrix of the control variable of the DP subsystem,
Figure FDA0003354435000000025
representing the imaginary matrix of the control variables of the DP subsystem,
Figure FDA0003354435000000026
a matrix representing the real part of the interaction quantity of the DP subsystem,
Figure FDA0003354435000000027
representing the imaginary matrix of the DP subsystem interaction quantities,
Figure FDA0003354435000000028
representing the real part of the real-time interaction quantity of the EMT subsystem,
Figure FDA0003354435000000029
represents the real-time interaction quantity imaginary part of the EMT subsystem,
Figure FDA00033544350000000210
representing the real part of the state variable of the DP subsystem,
Figure FDA00033544350000000211
representing the imaginary part of the state variable of the DP subsystem.
4. The method for analyzing the dynamic characteristics of the direct-current power system based on the hybrid time scale modeling as claimed in claim 1, wherein in the process of performing data interaction between the EMT calculation module and the DP calculation module by using the FPGA3, the adopted interface mechanism comprises:
extracting dynamic phasor values from the interaction quantity instantaneous values output by the EMT subsystem;
generating an interaction quantity instantaneous value by utilizing the interaction quantity in the form of the dynamic phasor output by the DP subsystem;
and the controlled voltage source and the controlled current source are used as interface circuits during single-step solution of the EMT subsystem and the DP subsystem, and the interaction quantity is used as the amplitude of the controlled source.
5. The method for analyzing dynamic characteristics of a dc power system based on hybrid time scale modeling according to claim 1, wherein in step S4, the initialization process comprises:
initializing an EMT calculation module of the EMT subsystem, a DP calculation module of the DP subsystem and an interface calculation module, wherein the initialization comprises the following steps: the time of the three modules is synchronous and the initial time is t ═ t0The simulation system comprises an EMT subsystem simulation step length delta T, a DP subsystem simulation step length delta T, a total simulation duration T, an EMT calculation module and a DP calculation module system parameter, wherein T0 indicates that the initial time is generally 0, and delta T indicates the EMT subsystem simulation step length.
6. The method for analyzing dynamic characteristics of a direct current power system based on mixed time scale modeling according to claim 1 or 5, wherein in step S4, the DP subsystem analyzes in a single step at a time, and comprises:
at the time t1, the interaction quantity in the form of the dynamic phasor output by the DP subsystem generates an instantaneous value sequence through an interface and transmits the instantaneous value sequence to the EMT subsystem;
the EMT subsystem reads the interaction quantity from the instantaneous value sequence, sets an interface circuit controlled source, and then analyzes according to the electromagnetic transient step length until the time t 2;
updating the instantaneous value sequence according to an analysis result obtained by the EMT subsystem, extracting a dynamic phasor value of the interaction quantity through a hybrid simulation interface, and transmitting the dynamic phasor value to the DP subsystem;
and the DP subsystem is executed to the time t2, and if the interaction interval is consistent with the simulation step length of the DP subsystem, only one iteration is carried out.
7. The hybrid time scale modeling based direct current power system dynamic characteristic analysis method according to claim 1 or 5, wherein in step S4, the EMT subsystem performs n times of single step length analysis, including:
at the time t1, the dynamic phasor form interaction quantity output by the DP subsystem generates an instantaneous value through a hybrid simulation interface, and then is transmitted to the EMT subsystem; and the EMT subsystem extracts the dynamic phasor value of the interaction quantity through an interface by utilizing the instantaneous value sequence and transmits the dynamic phasor value to the DP subsystem.
8. The method for analyzing the dynamic characteristics of the direct-current power system based on the hybrid time scale modeling according to claim 7, wherein in the case of adopting a serial time sequence processing mode, the method comprises the following steps:
at time t1, DP subsystem interaction vector dynamic phasor value<rD>kGeneration of a sequence of momentary values r via a hybrid simulation interfaceD,n＝{rD,n(t),…rD,n(t + (m-1) delta t) } and then transmitting the data to the EMT subsystem;
EMT subsystem from interaction quantity instantaneous value sequence rDSequentially reading the interaction quantity, setting an interface circuit controlled source, and executing simulation steps m according to the electromagnetic transient step length delta t until t 2;
by the EMT subsystem (t)1,t2]Simulation result, update [ t2-T,t2]The time interval interaction quantity instantaneous value sequence is used for extracting the interaction quantity dynamic phasor value through the hybrid simulation interface<rE>kAnd passed to the DP sub-system for (t)1,t2]Simulating time;
and the DP subsystem is executed to the time T2 by the simulation step length delta T, and if the interaction interval is consistent with the simulation step length of the DP subsystem, only one iteration is carried out.
9. The method for analyzing the dynamic characteristics of the direct-current power system based on the hybrid time scale modeling according to claim 7, wherein the method comprises the following steps of, when a parallel time-series processing mode is adopted:
at time t1, DP subsystem interaction vector dynamic phasor value<rD>kGeneration of a sequence of momentary values r via a hybrid simulation interfaceD,n＝{rD,n(t),…rD,n(t + (m-1) delta t) } and then transmitting the data to the EMT subsystem; at the same time, the EMT subsystem utilizes [ t ]1-T,t1]Time interval interaction quantity instantaneous value sequence, and interaction quantity dynamic phasor value is extracted through interface<rE>kAnd transmits to DP subsystem;
the EMT subsystem and the DP subsystem are respectively executed in step size delta T and delta T simulation until the time T2, and the DP subsystem updates the interaction quantity instantaneous value sequence to T2-T,t2]。
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