New energy power system electromagnetic continuous state space modeling method and system

Abstract

The invention provides a new energy power system electromagnetic continuous state space modeling method and system, and the method comprises the steps: building a continuous state space equation of each element of a system in a D-Q common rotating coordinate system, and building a differential equation of the whole system; identifying an independent state variable and a redundant state variable, rewriting a whole system differential equation, and establishing a KCL equation of each node by using an incidence matrix; converting a redundant differential equation into an algebraic equation by using the KCL equation; an original partial algebraic equation of the system and an algebraic equation of redundant state variable conversion are simultaneous with a differential equation of an independent state variable, and an electromagnetic small interference model of the new energy power system represented by a differential-algebraic equation is obtained; and deducing the electromagnetic small interference model into a system electromagnetic small interference model represented by a differential equation to form a final state space model. The method has a good and wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of power system state space modeling, and specifically relates to a new energy power system electromagnetic continuous state space modeling method and system. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The state space method is an effective method for small disturbance stability analysis of power systems. The existing continuous state space modeling method of power systems is to select independent state variables and then eliminate algebraic variables to establish a continuous state space model of the entire system. Different from the small disturbance state space modeling method of traditional power systems, the electromagnetic small disturbance state space modeling of new energy power systems faces new characteristics, that is, the electromagnetic transient characteristics of all components need to be taken into account, which will lead to abnormal networks in new energy power systems, which will make the independence between state variables not satisfied, resulting in redundant state variables that are difficult to eliminate.

[0004] Existing continuous state space modeling methods usually add a sufficiently large virtual resistor at the node to ensure independence between state variables, but this will lead to errors in system dynamic modeling. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a new energy power system electromagnetic continuous state space modeling method and system. During the modeling process, the present invention converts redundant differential equations into algebraic equations, and converts redundant branch currents or node voltages from state variables into algebraic variables, which has good and broad application prospects.

[0006] According to some embodiments, the present invention adopts the following technical solutions:

[0007] A method for electromagnetic continuous state space modeling of a new energy power system comprises the following steps:

[0008] Establish the continuous state space equations of each component of the system in the DQ common rotating coordinate system, and establish the differential equation of the whole system;

[0009] Identify independent state variables and redundant state variables, rewrite the differential equations of the whole system, and use the correlation matrix to establish the KCL equations of each node;

[0010] Using the KCL equation to convert the redundant differential equation into an algebraic equation;

[0011] The original partial algebraic equations of the system and the algebraic equations of redundant state variable conversion are combined with the differential equations of independent state variables to obtain the electromagnetic small interference model of the new energy power system represented by the differential-algebraic equation;

[0012] The electromagnetic small interference model is derived into a system electromagnetic small interference model represented by a differential equation to form a final state space model.

[0013] As an optional implementation, the process of establishing continuous state space equations of each system element in the DQ common rotating coordinate system includes establishing linearized differential equations of the inverter, linearized differential equations of the RL line, linearized differential equations of the RL load, and linearized differential equations of the parallel capacitor.

[0014] As an optional implementation, when establishing the continuous state space equations of each component of the system in the DQ common rotating coordinate system, the nodes are divided into two categories: nodes connected to the capacitor branch and intermediate nodes not connected to the capacitor branch, and then the linearized differential equations of the inverter, the linearized differential equations of the RL line and the linearized differential equations of the RL load are rewritten into general differential equations.

[0015] As an optional implementation, the process of identifying independent state variables and redundant state variables and rewriting the differential equations of the entire system includes: placing the redundant differential equations in the rewritten general differential equations in the last n2 rows and rewriting them in a block form, where n2 is the number of redundant state variables.

[0016] As an optional implementation, the process of converting redundant differential equations into algebraic equations using KCL equations established through an association matrix includes: substituting the KCL equations of each node established using the association matrix into the equations rewritten in block form, converting the differential equations corresponding to the redundant state variables into algebraic equations; and combining them with the KCL equations, and rewriting the combined equations into a compact form to form algebraic equations.

[0017] As an optional implementation, the process of combining the original partial algebraic equations of the system and the algebraic equations converted from redundant state variables with the differential equations of independent state variables includes: rewriting the KCL equations of each node established by using the association matrix into algebraic equations associated with the state variables and the redundant state variables;

[0018] Arrange the equations rewritten in block form;

[0019] By combining the algebraic equation and the rearranged equation, an electromagnetic small interference model of the new energy power system represented by a differential-algebraic equation is obtained.

[0020] As an optional implementation, the process of deriving the electromagnetic small interference model of the new energy power system represented by the differential-algebraic equation into the system electromagnetic small interference model represented by the differential equation includes:

[0021] As an optional implementation, according to the algebraic equations related to the state variables and the redundant state variables, the algebraic variables represented by the state variables are solved, and the algebraic variables are substituted into the sorted equations to calculate the state matrix of the system.

[0022] An electromagnetic continuous state space modeling system for a new energy power system, comprising:

[0023] The system differential equation building module is configured to establish the continuous state space equations of each component of the system in the DQ common rotating coordinate system and to establish the differential equations of the whole system;

[0024] A differential equation rewriting module is configured to identify independent state variables and redundant state variables, rewrite the differential equation of the whole system, and establish the KCL equation of each node using the correlation matrix;

[0025] A redundant conversion module, configured to convert redundant differential equations into algebraic equations using the KCL equations;

[0026] The simultaneous module is configured to simultaneously combine the original partial algebraic equations of the system and the algebraic equations of the redundant state variables with the differential equations of the independent state variables to obtain the electromagnetic small interference model of the new energy power system represented by the differential-algebraic equations;

[0027] The state space model building module is configured to derive the electromagnetic small interference model into a system electromagnetic small interference model represented by a differential equation to form a final state space model.

[0028] An electronic device comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor. When the computer instructions are executed by the processor, the steps in the above method are completed.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] When establishing an electromagnetic small interference state space model of a new energy power system containing an abnormal network, the present invention does not need to add virtual resistance at the node, and uses KCL and KVL to establish an algebraic relationship between the node voltage and the current of each branch connected to the node, thereby solving the problem that algebraic variables brought by the abnormal network are difficult to eliminate directly; in addition, the present invention can separate independent and redundant state variables, eliminate redundant state variables by reducing the order, and finally obtain a reduced-order system electromagnetic small interference model.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1 A flowchart of a method for modeling electromagnetic small interference state space of a new energy power system containing an abnormal network according to an embodiment;

[0034] Figure 2 A schematic diagram of an abnormal network in an embodiment;

[0035] Figure 3 The figure is a schematic diagram of a novel power system structure according to an embodiment. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] In the absence of conflict, the embodiments in this application and the features in the embodiments may be combined with each other.

[0040] State space modeling method for electromagnetic small disturbance of renewable energy power system containing abnormal network, such as Figure 1 As shown, the following steps are included:

[0041] S1: Establish the continuous state space equations of each component of the system in the DQ common rotating coordinate system, divide the nodes into two categories: nodes connected to the capacitor branch and intermediate nodes not connected to the capacitor branch, so as to establish the differential equation of the whole system;

[0042] S2: Identify independent state variables and redundant state variables, rewrite the differential equations of the whole system, and use the correlation matrix to establish the KCL equations of each node, including the algebraic equations of the system part;

[0043] S3: Convert the redundant differential equations into algebraic equations using the KCL equations established through the correlation matrix;

[0044] S4: The original partial algebraic equations of the system and the algebraic equations of the redundant state variables are combined with the differential equations of the independent state variables to obtain the electromagnetic small interference model of the new energy power system represented by the differential-algebraic equation (DAE);

[0045] S5: The electromagnetic small disturbance model of the new energy power system represented by the differential-algebraic equation (DAE) is further derived into the system electromagnetic small disturbance model represented by the differential equation (ODE).

[0046] So far, a state space model of electromagnetic small disturbance of new energy power system containing abnormal network has been successfully established.

[0047] In step S1, Figure 2 As shown, the continuous state space equations of each component of the system are established in the DQ common rotating coordinate system, and the nodes of the system are divided into two categories: nodes connected to the capacitor branch and intermediate nodes not connected to the capacitor branch, thereby establishing the differential equation of the whole system:

[0048] The linearized differential equation of the inverter is:

[0049]

[0050] In the formula, x inv is the state variable of the converter, i oDQ is the output current of the converter port in the DQ common rotating coordinate system, v bDQ is the port voltage of the converter in the DQ common rotating coordinate system, is the branch-node association matrix between the inverter branch and the system node, which contains the connection information between S inverters and all system nodes. The coefficient matrix is:

[0051]

[0052] in, Among them, n inv is the number of inverter state variables;

[0053] The linearized differential equation of the RL circuit is:

[0054]

[0055] In the formula, v bDQrepresents the voltage vector at both ends of the line in the DQ common rotating coordinate system, i lineDQ It represents the line current vector in the DQ common rotating coordinate system, and the coefficient matrix

[0056] The linearized differential equation of the RL load is:

[0057]

[0058] In the formula, v bDQ represents the voltage vector of the node where the load is located in the DQ common rotating coordinate system, i lineDQ It represents the current vector of the load branch in the DQ common rotating coordinate system, and the coefficient matrix

[0059]

[0060] The linearized differential equation for the shunt capacitor is:

[0061]

[0062] In the formula, v bDQ represents the voltage vector of the node where the parallel capacitor branch is located in the DQ common rotating coordinate system, i pcDQ represents the current vector of the parallel capacitor branch in the DQ common rotating coordinate system, the coefficient matrix, v bDQ represents the voltage vector of the node where the parallel capacitor branch is located in the DQ common rotating coordinate system, i pcDQ Represents the current vector of the parallel capacitor branch in the DQ common rotating coordinate system, and the coefficient matrix

[0063] The nodes of the system are divided into two categories: nodes connected to the capacitor branch and intermediate nodes not connected to the capacitor branch; let their node numbers be N pc and N inter , then N inter +N pc =N; remember

[0064] in is the voltage vector of the middle node. Therefore, equations (1) to (4) can be written as a general differential equation as shown in equation (6);

[0065]

[0066] In the formula,

[0067]

[0068] in, for The columns related to the parallel capacitor branch nodes are the first 2N pc List, The last 2N of B1 inter Column, where n′=n inv S+2L+2H.

[0069] In the step S2, the independent state variables and the redundant state variables are identified, the differential equation of the whole system is rewritten, and the KCL equation of each node is established using the correlation matrix, including the algebraic equation of the system part;

[0070] like Figure 3 As shown, (a) and (b) are schematic diagrams of abnormal networks containing inductor cut sets and capacitor loops, respectively. Let n1+n2=n, where n1 and n2 are the number of independent and redundant state variables, respectively. If the system has a capacitor loop, then n2=2N inter +2n pc , where n pc is the total number of capacitor loops; if the capacitors connected in parallel on the node are combined or there is no capacitor loop in the system, then n2=2N inter Put the redundant differential equation in equation (6) into the last n2 rows and rewrite it in block form, and we get:

[0071]

[0072] In the formula, is an independent state variable, is a redundant state variable; definition and for:

[0073]

[0074] Use the association matrix to establish the KCL equations for each node:

[0075] 0=CΔx+DΔy (10)

[0076] In the formula,

[0077]

[0078] Using formula (11), formula (10) can be rewritten as:

[0079]

[0080] In the formula, I Npc 2N pc The identity matrix of order 0 Ninter 2N interOrder zero matrix; definition definition in is the first n1 columns of C1, is the last n2 columns of C1.

[0081] In step S3, the redundant differential equations are converted into algebraic equations using the KCL equation established by the correlation matrix:

[0082] Substitute the second equation of equation (12) into equation (8) to transform the differential equation corresponding to the redundant state variables into an algebraic equation:

[0083]

[0084] In the formula,

[0085]

[0086] Formula (13) can be further organized as:

[0087]

[0088] Combining equation (15) with the second equation of equation (12), we get:

[0089]

[0090] Rewriting formula (16) into a compact form, we get:

[0091]

[0092] In step S4, the original partial algebraic equations of the system and the algebraic equations converted from redundant state variables are combined with the differential equations of independent state variables:

[0093] The first equation of equation (12) can be further rewritten as:

[0094] Δi pcDQ =C1 (1) Δx1+C1 (2) Δx2 (18)

[0095] Combining equation (17) and equation (18), we get:

[0096]

[0097] The first and third equations of formula (19) represent the KCL equations of the node connected to the capacitor branch and the intermediate node not connected to the capacitor branch, respectively, corresponding to the first and second equations of formula (12) respectively; the second equation is the physical equation related to the redundant state variable, which establishes the algebraic variable Δv interDQAlgebraic equations relating the state variable Δx1 and the redundant state variable Δx2;

[0098] The first equation of equation (8) can be further rearranged as follows:

[0099]

[0100] Therefore, equation (20) and equation (19) are the electromagnetic small disturbance model of the new energy power system expressed by the differential-algebraic equation (DAE); the electromagnetic small disturbance model of the system expressed by the differential equation (ODE) is further derived below.

[0101] In step S5, the electromagnetic small interference model of the new energy power system represented by the differential-algebraic equation (DAE) is further derived into the system electromagnetic small interference model represented by the differential equation (ODE):

[0102] The algebraic variables represented by the state variables are obtained by solving equation (19):

[0103]

[0104] Substituting formula (21) into formula (20), we get:

[0105]

[0106] Formula (22) can be further organized as:

[0107]

[0108] So, the state matrix of the system is for:

[0109]

[0110] In the formula,

[0111]

[0112] Finally, the state matrix of the system can be directly expressed as:

[0113]

[0114] Embodiment 2

[0115] An electromagnetic continuous state space modeling system for a new energy power system, comprising:

[0116] The system differential equation building module is configured to establish the continuous state space equations of each component of the system in the DQ common rotating coordinate system and to establish the differential equations of the whole system;

[0117] A differential equation rewriting module is configured to identify independent state variables and redundant state variables, rewrite the differential equation of the whole system, and establish the KCL equation of each node using the correlation matrix;

[0118] A redundant conversion module, configured to convert redundant differential equations into algebraic equations using the KCL equations;

[0119] The simultaneous module is configured to simultaneously combine the original partial algebraic equations of the system and the algebraic equations of the redundant state variables with the differential equations of the independent state variables to obtain the electromagnetic small interference model of the new energy power system represented by the differential-algebraic equations;

[0120] The state space model building module is configured to derive the electromagnetic small interference model into a system electromagnetic small interference model represented by a differential equation to form a final state space model.

[0121] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention without creative labor shall be included in the protection scope of the present invention.

Claims

1. A method for electromagnetic continuous state space modeling of a new energy power system, characterized in that: The following steps are involved: exist DQ The common rotating coordinate system establishes the continuous state space equations of each component of the system and the differential equations of the whole system; Identify independent state variables and redundant state variables, rewrite the differential equations of the whole system, and use the correlation matrix to establish the KCL equations of each node; Using the KCL equation to convert the redundant differential equation into an algebraic equation; The original partial algebraic equations of the system and the algebraic equations of redundant state variable conversion are combined with the differential equations of independent state variables to obtain the electromagnetic small interference model of the new energy power system represented by the differential-algebraic equation; The electromagnetic small interference model is derived into a system electromagnetic small interference model represented by a differential equation to form a final state space model.

2. The electromagnetic continuous state space modeling method of a new energy power system according to claim 1, characterized in that: exist DQ The process of establishing the continuous state space equations of each component of the system in a common rotating coordinate system includes establishing the linearized differential equations of the inverter, the linearized differential equations of the RL line, the linearized differential equations of the RL load, and the linearized differential equations of the shunt capacitor.

3. A method for electromagnetic continuous state space modeling of a new energy power system as claimed in claim 2, characterized in that: exist DQ When the continuous state space equations of each component of the system are established in a common rotating coordinate system, the nodes are divided into two categories: nodes connected to the capacitor branch and intermediate nodes not connected to the capacitor branch. Then, the linearized differential equations of the inverter, the linearized differential equations of the RL line and the linearized differential equations of the RL load are rewritten as general differential equations.

4. The electromagnetic continuous state space modeling method of a new energy power system according to claim 1, characterized in that: The process of identifying independent state variables and redundant state variables and rewriting the differential equation of the whole system includes: putting the redundant differential equations in the rewritten general differential equation at the end n 2 lines, and rewrite it in block form, n 2 is the number of redundant state variables.

5. The electromagnetic continuous state space modeling method of a new energy power system according to claim 1, characterized in that: The process of converting redundant differential equations into algebraic equations using KCL equations established through an association matrix includes: substituting the KCL equations of each node established using the association matrix into the equations rewritten in block form, converting the differential equations corresponding to the redundant state variables into algebraic equations; and combining them with the KCL equations, and rewriting the combined equations into a compact form to form algebraic equations.

6. The electromagnetic continuous state space modeling method of a new energy power system according to claim 1, characterized in that: The process of combining the original partial algebraic equations of the system and the algebraic equations converted by redundant state variables with the differential equations of independent state variables includes: rewriting the KCL equations of each node established by using the association matrix into algebraic equations associated with the state variables and the redundant state variables; Arrange the equations rewritten in block form; By combining the algebraic equation and the rearranged equation, an electromagnetic small interference model of the new energy power system represented by a differential-algebraic equation is obtained.

7. A method for electromagnetic continuous state space modeling of a new energy power system as claimed in claim 6, characterized in that: The electromagnetic small disturbance model of the new energy power system represented by differential-algebraic equations is derived into the system electromagnetic small disturbance model represented by differential equations.

8. The electromagnetic continuous state space modeling method of a new energy power system according to claim 7, characterized in that: According to the algebraic equations related to the state variables and the redundant state variables, the algebraic variables represented by the state variables are solved, and the algebraic variables are substituted into the rearranged equations to calculate the state matrix of the system.

9. A new energy power system electromagnetic continuous state space modeling system, characterized by: include: The system differential equation building blocks are configured to DQ The common rotating coordinate system establishes the continuous state space equations of each component of the system and the differential equations of the whole system; A differential equation rewriting module is configured to identify independent state variables and redundant state variables, rewrite the differential equation of the whole system, and establish the KCL equation of each node using the correlation matrix; A redundant conversion module, configured to convert redundant differential equations into algebraic equations using the KCL equations; The simultaneous module is configured to simultaneously combine the original partial algebraic equations of the system and the algebraic equations of the redundant state variables with the differential equations of the independent state variables to obtain the electromagnetic small interference model of the new energy power system represented by the differential-algebraic equations; The state space model building module is configured to derive the electromagnetic small interference model into a system electromagnetic small interference model represented by a differential equation to form a final state space model.

10. An electronic device, characterized in that: The method comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the steps in the method according to any one of claims 1 to 8 are completed.

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