WO2018209481A1

WO2018209481A1 - Lossless symmetric method for obtaining power transmission coefficient of direct-current power grid

Info

Publication number: WO2018209481A1
Application number: PCT/CN2017/084288
Authority: WO
Inventors: 彭建春; 江辉
Original assignee: 深圳大学
Priority date: 2017-05-15
Filing date: 2017-05-15
Publication date: 2018-11-22
Also published as: CN109845062A; CN109845062B

Abstract

A lossless symmetric method for obtaining a power transmission coefficient of a direct-current power grid comprises: first, according to a node load parameter and a node power supply parameter in a direct-current power grid, establishing a lossless global linear relation about a node injection power and a node translation voltage (101); then, establishing a steady-state lossless global linear symmetric model of the direct-current power grid according to the lossless global linear relation (102); by using an M-P inverse matrix, establishing a lossless global linear symmetric matrix relation about a whole-network node translation voltage and a whole-network node injection power according to the lossless global linear symmetric model (103); then; establishing a lossless global linear symmetric relation about a branch transmission power and the whole-network node injection power (104); and finally, obtaining a power transmission coefficient of the direct-current power grid according to the lossless global linear symmetric relation and a definition of the power transmission coefficient (105). By means of the lossless symmetric method for obtaining a power transmission coefficient of a direct-current power grid, a high precision is achieved, fast and reliable computing is also achieved, and the accuracy and the real-time performance of adjustment and control are improved when the operating state of the power grid changes in a wide range.

Description

A lossless symmetric method for obtaining the power transmission coefficient of a DC power network

Technical field

The present invention relates to the field of power engineering, and in particular, to a lossless symmetrical method for obtaining a power transmission coefficient of a DC power network.

Background technique

DC power grid is an emerging power transmission network. Drawing on the control method of the traditional AC power network branch road safety, the power transmission coefficient of the DC power network is an indispensable tool for the control of its branch safety. Therefore, an accurate, fast and reliable method for obtaining the power transmission coefficient of the DC power network needs to be developed.

The global linear acquisition method of the power transmission coefficient of the AC power grid is based on the assumption that the voltage amplitude of each node is equal to 1.0 p.u. and the voltage phase difference between the nodes of each branch is close to zero, simplifying the steady state model of the AC power grid. The node voltage in the DC power network only contains amplitude (excluding phase). If the voltage of each node is assumed to be equal to 1.0 pu, the power transmitted by each branch is always zero. The AC power network theory cannot be used to obtain the global power transmission coefficient of the DC power network. Linear acquisition method. If the steady-state model based on the linearization of the DC power network is used to obtain the power transmission coefficient of the DC power network, the local linear characteristics cannot meet the accuracy requirements of the safety regulation of the branch when the operating state of the DC power network changes widely. Therefore, there is no global linear acquisition method for the DC power network power transmission coefficient, and the existing local The linearization acquisition method is not suitable for a wide range of changes in the operating state of the DC power network.

Summary of the invention

Embodiments of the present invention provide a lossless symmetric method for acquiring a power transmission coefficient of a DC power network, which can realize global linearization of a power transmission coefficient of a DC power network.

The invention provides a lossless symmetry method for obtaining a power transmission coefficient of a DC power network, comprising:

Establishing a lossless global linear relationship of the node injection power with respect to the node translation voltage according to the node load parameter and the node power parameter in the known DC power network;

Establishing a lossless global linear symmetric model of the steady state of the DC power network according to the lossless global linear relationship;

According to the lossless global linear symmetric model, the M-P inverse matrix is used to establish a lossless global linear symmetric matrix relationship of the whole network node translation voltage with respect to the injection power of the whole network node;

Establishing a lossless global linear symmetric relationship of the branch transmission power with respect to the injection power of the entire network according to the lossless global linear symmetric matrix relationship;

Obtaining a power transmission coefficient of the DC power network according to the lossless global linear symmetric relationship and a definition of a known power transmission coefficient.

The embodiment of the present invention first establishes a lossless global linear relationship of the node injection power with respect to the node translation voltage according to the node load parameter and the node power parameter in the known DC power network; and then establishes a DC power network according to the lossless global linear relationship. Steady-state lossless global linear symmetric model; utilized according to a lossless global linear symmetric model The MP inverse matrix establishes the lossless global linear symmetric matrix relation of the whole network node translation voltage with respect to the injection power of the whole network node; then establishes the branch transmission power according to the lossless global linear symmetric matrix relation. Linear symmetric relationship; finally obtain the power transmission coefficient of the DC power network according to the definition of the lossless global linear symmetric relation and the known power transmission coefficient; because the steady state model of the DC power network is adopted, the power loss is ignored, and the error rate Very close to the power loss rate of the power grid, so the accuracy is high; and because of its global linear characteristics, it not only calculates the power transmission coefficient of any structure DC power grid quickly and reliably, but also adapts to the accuracy and real-time regulation of the power network operating state. Sexual requirements. Therefore, the method for obtaining the global linear power transmission coefficient of the DC power network is not solved, and the local linearization acquisition method is not suitable for the problem that the DC power network operating state changes widely.

DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are some embodiments of the present invention. For the ordinary technicians, other drawings can be obtained based on these drawings without any creative work.

1 is a flowchart of an implementation of a lossless symmetric method for acquiring a power transmission coefficient of a DC power network according to an embodiment of the present invention;

2 is a schematic structural diagram of a general model of a DC power network according to an embodiment of the present invention.

detailed description

In the following description, for purposes of illustration and description However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the invention.

In order to explain the technical solution described in the present invention, the following description will be made by way of specific embodiments.

Referring to FIG. 1, FIG. 1 is a flowchart of implementing a lossless symmetric method for acquiring a power transmission coefficient of a DC power network according to an embodiment of the present invention. The lossless symmetric method for obtaining the DC power network power transmission coefficient as shown in the figure may include the following steps:

In step 101, a lossless global linear relationship of the node injection power with respect to the node translation voltage is established based on the node load parameters and the node power parameters in the known DC power grid.

Step 101 is specifically: establishing a lossless global linear relationship of the node injection power with respect to the node translation voltage according to the following relationship:

Where i and k are the numbers of the nodes in the DC power network, and both belong to the set of consecutive natural numbers {1, 2,..., n}; n is the total number of nodes in the DC power network; P _Gi is connected Power supply to node i; P _Di is the load power connected to node i, P _Gi -P _Di is the injection power of node i; g _ik is the conductance of branch ik connected between node i and node k; _i is the translation voltage of node i; v _k is the translation voltage of node k, and both v _i and v _k are the target voltages after translation -1.0.

Among them, P _Gi , P _Di , n, g _ik are all known DC power network parameters.

The above lossless global linear relationship is established based on the operating characteristics of the DC power network. The operating characteristic of the DC power network is that the "node translation voltage" obtained after the voltage of each node in the DC power network is -1.0 is small, so that the product of the branch conductance and the square of the translation voltage of one end node, the branch conductance and its two end nodes The product of the translation voltage is always close to zero and can be ignored.

All the variables in the above lossless global linear relation are global variables, not increments, and the two sides of the relationship do not contain the power loss of the power network that needs to be expressed by a quadratic function, which is called the above relationship is the node injection power. The reason for the lossless global linear relationship of the node translation voltage.

In step 102, a lossless global linear symmetric model of the steady state of the DC power network is established according to the lossless global linear relationship.

Step 102 is specifically: establishing a steady-state lossless global linear symmetric model of the DC power network according to the following relationship:

Where P _G1 is the power supply power connected to node 1; P _Gi is the power supply power connected to node i; P _Gn is the power supply power connected to node n; P _D1 is the load power connected to node 1; P _Di is connected The load power at node i; P _Dn is the load power connected to node n; j is the number of nodes in the DC power network, and belongs to the set of consecutive natural numbers {1, 2, ..., n}; g _ij is connected to the node The conductance of the branch ij between i and node j; g _ik is the conductance of the branch _ik connected between node i and node k; n is the total number of nodes in the DC power network; (G _ij ) is The original node conductance matrix of the DC power network, the dimension of the original node conductance matrix is n×n; G _ij is the element of the i-th row and the j-th column of the original node conductance matrix (G _ij ); v ₁ is the translation voltage of the node 1 ; v _i is the translation voltage of node i; v _n is the translation voltage of node n, and v ₁ , v _i and v _n are the target voltages after translation -1.0.

Among them, P _G1 , P _D1 , P _Gi , P _Di , P _Gn , P _Dn , (G _ij ) are known DC power network parameters.

In the above lossless global linear symmetric model, the no-node translation voltage is assigned a reference voltage center of zero value, and the translation voltage and the injection power of each node of the whole network are treated unbiasedly, that is, symmetrically treated, which is positive It is said that the above model is a lossless global linear symmetric model.

In step 103, according to the lossless global linear symmetric model, the M-P inverse matrix is used to establish a lossless global linear symmetric matrix relationship of the whole network node translation voltage with respect to the total network node injection power.

Step 103 is specifically: establishing a lossless global linear symmetric matrix relationship of the whole network node translation voltage with respect to the injection power of the whole network node according to the following relationship:

Where (a _ij ) and (G _ij ) ⁺ are the MP inverse matrix of the original node conductance matrix (G _ij ) of the DC power network; P _G1 is the power supply power connected to node 1; P _Gi is connected to node i Power supply power; P _Gn is the power supply power connected to node n; P _D1 is the load power connected to node 1; P _Di is the load power connected to node i; P _Dn is the load power connected to node n; v ₁ is The translation voltage of node 1; v _i is the translation voltage of node i; v _n is the translation voltage of node n, and v ₁ , v _i and v _n are the standard value voltages after translation -1.0.

Since the above-mentioned lossless global linear symmetric matrix relation is a global variable (rather than an incremental) relation, the translation voltage of each node in the whole network is calculated according to the large variation of the node injection power, that is, the DC power network has a large operating state. The range is accurate when it changes, and the linear features make calculations fast and reliable.

In step 104, a lossless global linear symmetric relationship of the branch transmission power with respect to the injection power of the entire network node is established according to the lossless global linear symmetric matrix relationship.

Step 104 is specifically:

The lossless global linear symmetric relationship of the branch transmission power with respect to the injection power of the whole network node is established according to the following relationship:

Where g _ik is the conductance of the branch ik connected between node i and node k; P _ik is the power transmitted by branch ik; n is the total number of nodes in the DC power network; a _ij is the DC power network Element of the i-th row and j-th column of the MP inverse matrix of the original node conductance matrix (G _ij ); a _kj is the k-th row and the j-th column of the MP inverse matrix of the original node conductance matrix (G _ij ) of the DC power network Element; P _Gj is the power of the power connected to node j; P _Dj is the load power connected to node j, and P _{Gj -} P _Dj is the injected power of node j.

In step 105, according to the lossless global linear symmetric relationship and the known power transfer The definition of the transmission coefficient obtains the power transmission coefficient of the DC power network.

Step 105 is specifically as follows:

Calculate the power transfer coefficient of the DC power network according to the following relationship:

D _ik,j =(a _ij -a _kj )g _ik

Where g _ik is the conductance of the branch ik connected between node i and node k; D _ik,j is the power transfer coefficient from node j to branch ik; a _ij is the original node conductance matrix of the DC power network ( An element of the i-th row and the j-th column of the MP inverse matrix of G _ij ); a _kj is an element of the k-th row and the j-th column of the MP inverse matrix of the original node conductance matrix (G _ij ) of the direct current power network.

The power transmission coefficient is defined as the linear combination of the branch transmission power expressed as the node injection power, and the combination coefficient is the power transmission coefficient.

For all combinations of branches and nodes in the DC power network, all the results calculated according to the above relationship are the power transmission coefficients of the DC power network, thereby realizing the acquisition of the power transmission coefficient of the DC power network.

The above relationship is based on the M-P inverse matrix of the original node conductance matrix of the DC power network, and the inverse matrix must exist, so it can be reliably obtained. In addition, the global linear characteristic of the relationship between the above-mentioned branch transmission power and the injection power of the entire network node makes the calculation of the power transmission coefficient accurate and fast when the operating state of the DC power network changes widely. Therefore, this lossless symmetrical method for obtaining the power transmission coefficient of the DC power network is accurate, fast, and reliable.

It should be understood that the size of the sequence of the steps in the above embodiments does not mean that the order of execution is performed, and the order of execution of each process should be determined according to its function and internal logic, and should not be construed as limiting the implementation process of the embodiments of the present invention.

One of ordinary skill in the art will recognize that the embodiments disclosed herein are described in connection with the embodiments disclosed herein. The illustrated unit and algorithm steps can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods for implementing the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present invention.

Claims

A lossless symmetric method for obtaining a power transmission coefficient of a DC power network, characterized in that the lossless symmetric method for obtaining a power transmission coefficient of a DC power network includes:

Establishing a lossless global linear relationship of the node injection power with respect to the node translation voltage according to the node load parameter and the node power parameter in the known DC power network;

Establishing a lossless global linear symmetric model of the steady state of the DC power network according to the lossless global linear relationship;

According to the lossless global linear symmetric model, the M-P inverse matrix is used to establish a lossless global linear symmetric matrix relationship of the whole network node translation voltage with respect to the injection power of the whole network node;

Establishing a lossless global linear symmetric relationship of the branch transmission power with respect to the injection power of the entire network according to the lossless global linear symmetric matrix relationship;

Obtaining a power transmission coefficient of the DC power network according to the lossless global linear symmetric relationship and a definition of a known power transmission coefficient.
The lossless symmetry method for acquiring a power transmission coefficient of a DC power network according to claim 1, wherein the node injection power is determined according to a node load parameter and a node power parameter in a known DC power network; The lossless global linear relationship is specifically as follows:

The lossless global linear relationship of the node injection power with respect to the node translation voltage is established according to the following relationship:

Where i and k are the numbers of the nodes in the DC power network, and both belong to the set of consecutive natural numbers {1, 2, ..., n}; n is the total number of nodes in the DC power network; P Gi Is the power supply to the node i; P Di is the load power connected to the node i, P Gi -P Di is the injection power of the node i; g ik is connected between the node i and the node k The conductance of the branch ik; v i is the translation voltage of the node i; v k is the translation voltage of the node k, and the v i and the v k are both the standard value voltage after the translation -1.0 .
The lossless symmetry method for obtaining a power transmission coefficient of a DC power network according to claim 1, wherein the lossless global linear symmetry model for establishing a steady state of the DC power network according to the lossless global linear relationship is specifically :

Establish a steady-state lossless global linear symmetry model of the DC power grid according to the following relationship:

Wherein, P G1 is the power supply power connected to the node 1; P Gi is the power supply power connected to the node i; P Gn is the power supply power connected to the node n; P D1 is the load power connected to the node 1; P Di Is the load power connected to the node i; P Dn is the load power connected to the node n; j is the number of nodes in the DC power network, and belongs to the set of consecutive natural numbers {1, 2, ..., n }; g ij is the conductance of the branch ij connected between the node i and the node j; g ik is the conductance of the branch ik connected between the node i and the node k; n is the The total number of nodes in the DC power network; (G ij ) is the original node conductance matrix of the DC power network, the dimension of the original node conductance matrix is n×n; G ij is the original node conductance matrix (G The element of the i-th row and the j-th column in ij ); v 1 is the translation voltage of the node 1; v i is the translation voltage of the node i; v n is the translation voltage of the node n, and the v 1 The v i and the v n are both standard value voltages after translation -1.0.
The lossless symmetry method for acquiring a power transmission coefficient of a DC power network according to claim 1, wherein said using said MP inverse matrix to establish a translation voltage of a whole network node according to said lossless global linear symmetric model The lossless global linear symmetric matrix relationship of injected power is specifically as follows:

The lossless global linear symmetric matrix relation of the whole network node translation voltage with respect to the injection power of the whole network node is established according to the following relationship:

Wherein, (a ij ) and (G ij ) + are the MP inverse matrix of the original node conductance matrix (G ij ) of the DC power network; P G1 is the power supply power connected to node 1; P Gi is connected to the node i power supply power; P Gn is the power supply power connected to the node n; P D1 is the load power connected to the node 1; P Di is the load power connected to the node i; P Dn is connected to the node The load power of n; v 1 is the translation voltage of the node 1; v i is the translation voltage of the node i; v n is the translation voltage of the node n, and the v 1 , the v i and the V n is the standard value voltage after translation -1.0.
Obtaining the loss of the power transmission coefficient of the DC power network according to claim 1 A symmetry-consuming method, wherein the lossless global linear symmetric relationship between the branch transmission power and the total network node injection power according to the lossless global linear symmetric matrix relationship is:

The lossless global linear symmetric relationship of the branch transmission power with respect to the injection power of the whole network node is established according to the following relationship:

Where g ik is the conductance of the branch ik connected between node i and node k; P ik is the power transmitted by said branch ik; n is the total number of nodes in said DC power network; a ij the DC power is an original network node conductance matrix (G ij) of the MP element in the inverse matrix of the i-th row j-th column; a kj original node is the conductance matrix DC power grid (G ij) is the inverse matrix MP The element of the kth row and the jth column; P Gj is the power of the power connected to the node j; P Dj is the load power connected to the node j, and P Gj - P Dj is the injection power of the node j.
The lossless symmetry method for obtaining a DC power network power transmission coefficient according to claim 1, wherein said obtaining said DC power according to said lossless global linear symmetric relationship and a definition of a known power transmission coefficient The power transmission coefficient of the network is specifically:

Calculating the power transmission coefficient of the DC power network according to the following relationship:

D ik,j =(a ij -a kj )g ik

Where g ik is the conductance of the branch ik connected between node i and node k; D ik,j is the power transfer coefficient from said node j to said branch ik; a ij is said DC power network The elements of the i-th row and the j-th column of the MP inverse matrix of the original node conductance matrix (G ij ); a kj is the k-th row of the MP inverse matrix of the original node conductance matrix (G ij ) of the DC power network The elements of the column.