WO2018209478A1

WO2018209478A1 - Equivalent conductance compensation global linear eccentric method for acquiring load flow of direct current power grid

Info

Publication number: WO2018209478A1
Application number: PCT/CN2017/084284
Authority: WO
Inventors: 江辉; 彭建春
Original assignee: 深圳大学
Priority date: 2017-05-15
Filing date: 2017-05-15
Publication date: 2018-11-22
Also published as: CN109257949A; CN109257949B

Abstract

An equivalent conductance compensation global linear eccentric method for acquiring the load flow of a direct current power grid: on the basis of node load parameters and node power supply parameters in a direct current power grid, establishing an equivalent conductance compensation global linear relationship equation of node injection power with respect to node translation voltage (101); on the basis of the equivalent conductance compensation global linear relationship equation and a reference node number, establishing an equivalent conductance compensation global linear eccentric model for the direct current power grid power flow (102); on the basis of the equivalent conductance compensation global linear eccentric model, establishing an equivalent conductance compensation global linear eccentric matrix relationship equation of non-reference node translation voltage with respect to non-reference node injection power (103); and, on the basis of the equivalent conductance compensation global linear eccentric matrix relationship equation and reference node translation voltage, calculating the voltage of each node and the transmission power of each branch in the direct current power grid (104). The amount of calculation is small, there are no convergence problems, and accuracy is high when the operating state of the direct current power grid changes greatly.

Description

Equal-conductance compensation global linear eccentricity method for obtaining DC power network power flow

Technical field

The invention relates to the field of electric power engineering, in particular to an equal-conductance compensation type global linear eccentricity method for acquiring a power flow of a direct current power network.

Background technique

At present, the technical and economic advantages of HVDC transmission are rapidly driving the construction and development of DC power grids. As a basis for the regulation of DC power network, the trend, especially the fast, reliable and accurate global linear power flow model and calculation method need to be developed.

The existing DC power network power flow acquisition method is to first establish a nonlinear node power balance equation model, and then use an iterative method to solve. Due to the nonlinearity of the node power balance equation model, this method not only has a large amount of iterative computation and slow speed, but also has an iterative non-convergence or unreliable convergence problem. It is difficult to adapt to the DC power network operation that needs to be controlled based on the power flow solution. Claim. If the local linear power flow model based on the running base point linearization is adopted, the accuracy requirement of the regulation of the DC power network operating state can not be satisfied. Therefore, the existing DC power network power flow acquisition method either has a problem of slow calculation speed and unreliable convergence, or does not adapt to a wide range of changes in the operating state of the DC power network.

Summary of the invention

Embodiments of the present invention provide an equal-conductance compensation type for acquiring a power flow of a DC power network The global linear eccentricity method can realize the fast and reliable acquisition of the DC power network power flow, and adapt to the wide range of operation of the DC power network.

The invention provides an equal-conductance compensation global linear eccentricity method for acquiring a power flow of a DC power network, comprising:

Establishing an equal-conductance compensation global linear relationship of the node injection power with respect to the node translation voltage according to the known node load parameter and the node power parameter in the DC power network;

Establishing an equal-conductance compensation global linear eccentricity model of the tidal current in the DC power network according to the equal-conductance compensation global linear relationship and the known reference node number;

According to the equal-conductance compensation type global linear eccentricity model, an inverse matrix is used to establish an equivalent-conductance-compensated global linear eccentric matrix relation of the non-reference node translation voltage with respect to the non-reference node injection power;

Calculating a voltage value of each node in the DC power network and a transmission power value of each branch according to the equal-conductance compensation type global linear eccentric matrix relationship and the known reference node translation voltage value.

The embodiment of the present invention first establishes an equal-conductance compensation 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 according to the equal-conductance compensation type global linearity The relational and known reference node numbers establish an equal-conductance-compensated global linear eccentricity model for the tidal current in the DC power network; and then use the inverse matrix to establish the non-reference node translation voltage based on the equal-conductance-compensated global linear eccentricity model. The equal-conductance-compensated global linear eccentric matrix relation of the node injection power; finally, the sections in the DC power network are calculated according to the equivalent-conductance-compensated global linear eccentric matrix relation and the known reference node translation voltage value. The voltage value of the point and the transmission power value of each branch; since iterative calculation is not required, the calculation amount is small, there is no convergence problem, and the accuracy is high when the operating state of the DC power network is widely changed.

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.

FIG. 1 is a flowchart of an implementation of an equal-conductance compensation global linear eccentricity method for acquiring a power flow of a DC power network according to an embodiment of the present invention; FIG.

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 schematic diagram of obtaining a DC power network trend according to an embodiment of the present invention. Flowchart of implementation of an equal-conductance compensation type global linear eccentricity method. The equal-conductance compensation global linear eccentricity method for obtaining the DC power network power flow as shown in the figure may include the following steps:

In step 101, an equal-conductance compensation global linear relationship of the node injection power with respect to the node translation voltage is established according to the node load parameter and the node power parameter in the known DC power network.

Step 101 is specifically: establishing an equal-conductance compensation 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 The power of the power at node i; P _Di is the load power connected to node i; P _Gi -P _Di is the injected power of node i; g _ik is the conductance of the branch ik connected between node i and node k; _I0 is the base point translation voltage of node i, and is the standard value voltage after translation -1.0; υ _i is the translation voltage of node i; υ _k is the translation voltage of node k, and υ _i and υ _k are both translation -1.0 After the standard value voltage;

P _Gi , P _Di , n, g _ik , υ _i0 are known DC power network parameters.

All variables in the above-mentioned equivalent conductance compensation global linear relation are global variables, not increments; in addition, the coefficients of υ _i and υ _k in the above-mentioned equivalent conductance compensation global linear relation (1+υ _i0 )g _Ik and -(1+υ _i0 )g _ik are self-conducting and mutual conductance, respectively, which increase the conductance terms _{0 i0} g _ik and -υ _i0 g _ik , respectively, compared to conventional self-conductance and mutual conductance. The two equal-numbered conductance terms are obtained by summing the nonlinear term of the original power expression on the right side of the above-mentioned equivalent-conductance compensation type global linear relation by the combination variable (υ _i -υ _k ) and quantizing the coefficient at the base point. The resulting nonlinear term used to compensate for the original power expression. This is why the above relationship is called the equivalent-conductance compensation global linear relation of the node injection power with respect to the node translation voltage.

The above-mentioned equivalent conductance compensation type global linear relationship is established according to 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 shifted to -1.0 is small. When the product of the branch conductance and the translation voltage of the terminal node is replaced by a constant, the accuracy of the result is small.

In step 102, an equal-conductance-compensated global linear eccentricity model of the tidal current in the DC power network is established according to the equal-conductance compensation-type global linear relationship and the known reference node number.

Step 102 is specifically: establishing an equal-conductance compensation global linear eccentricity model of the power flow in the DC power network according to the following relationship:

Where P _G1 is the power supply of node 1; P _Gi is the power supply of node i; P _Gn-1 is the power supply of node n-1; P _D1 is the load power of node 1; P _Di is the load power of node i P _Dn-1 is the load power of node n-1; j is the number of nodes in the DC power network, and belongs to the set of continuous natural numbers {1, 2,..., n}; g _ij is connected to node i and node j The conductance between the branches ij; g _ik is the conductance of the branch _ik connected between the node i and the node k; υ _i0 is the base point translation voltage of the node i, and is the target value voltage after the translation -1.0; n is the total number of nodes in the DC power network; the node numbered n is a known reference node; (G _ij ) is the equivalent conductance compensation type node conductance of the DC power network after deleting the row and column of the reference node The dimension of the matrix, the equivalent conductance compensation type node conductance matrix is (n-1) × (n-1); G _ij is the element of the i-th row and the j-th column of the equal-conductance compensated node conductance matrix (G _ij ) ; υ ₁ is the translation voltage of node 1; υ _i is the translation voltage of node i; υ _n-1 is the translation voltage of node n-1, and υ ₁ , υ _i and υ _n-1 are both after translation -1.0 Standard Value voltage.

Among them, P _G1 , P _D1 , P _Gi , P _Di , P _Gn-1 , P _Dn-1 , (G _ij ) are known DC power network parameters.

In the above-mentioned equal-conductance-compensated global linear eccentricity model, the translational voltage of the reference node is assigned to a voltage center of zero value, and the center is completely biased toward the reference node, which is called the above-mentioned model is an equal-conductance-compensated global linear eccentricity model. reason.

In step 103, according to the equal-conductance compensation type global linear eccentricity model, an inverse matrix is used to establish an equal-conductance-compensated global linear eccentric matrix relation of the non-reference node translation voltage with respect to the non-reference node injection power.

Step 103 is specifically: establishing an equal-conductance compensation global linear eccentric matrix relationship of the non-reference node translation voltage with respect to the non-reference node injection power according to the following relationship:

Where (G _ij ) ^-1 is the inverse matrix of the equivalent conductance compensation node conductance matrix (G _ij ) of the DC power network; P _G1 is the power supply of node 1; P _Gi is the power supply of node i; P _{Gn- 1} is the power supply of node n-1; P _D1 is the load power of node 1; P _Di is the load power of node i; P _Dn-1 is the load power of node n-1; υ ₁ is the translation voltage of node 1; υ _i is the translation voltage of node i; υ _n-1 is the translation voltage of node n-1, and υ ₁ , υ _i and υ _n-1 are the target voltages after translation -1.0. According to the above relationship, the non-reference node translation voltage values υ _i , i=1, 2, . . . , n-1 can be calculated.

Since the above-mentioned equivalent conductance compensation type global linear eccentric matrix relation is a global variable (rather than an incremental) relation, the non-reference node translation voltage calculated according to it changes when the node injection power varies widely, that is, the DC power network operates. The state is accurate when the range is changed, and the calculation process involves only one simple linear relationship calculation, fast and reliable.

In step 104, the voltage values of the nodes in the DC power network and the transmission power values of the branches are calculated according to the equal-conductance compensation type global linear eccentric matrix relationship and the known reference node translation voltage values.

Step 104 is specifically: calculating a non-reference node translation voltage value according to an equal-conductance compensation type global linear eccentric matrix relation; and calculating a non-reference in the DC power network according to the following reference node translation voltage values according to the following three relations Node voltage value, reference node voltage value and transmission power value of each branch:

V _i =1+υ _i +υ _n

V _n =1+υ _n

P _ij =g _ij (υ _i -υ _j )

Wherein, V _{i is a} non-reference node voltage value, i=1, 2, . . . , n−1; V _n is a reference node voltage value; υ _n is a reference node translation voltage value, and is a target value after translation-1.0 Voltage; υ _i is the translation voltage of node i; υ _j is the translation voltage of node j, and υ _i and υ _j are the standard value voltages after translation -1.0; g _ij is connected between node i and node j The conductance of the branch ij; P _ij is the branch ij transmission power value, also known as the branch current.

In this way, the distribution of the global conductance compensation type global linear power flow of the DC power network is obtained. The above relationship is very simple with the non-reference node translation voltage as the core. The calculation of the non-reference node translation voltage is accurate, fast and reliable when the operating state of the DC power network varies widely. Therefore, the equal-conductance-compensated global linear eccentricity model and algorithm for tidal currents in such DC power networks are 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.

Those of ordinary skill in the art will appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein 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

An equal-conductance compensation global linear eccentricity method for obtaining a power flow of a DC power network, characterized in that the method for obtaining an equal-conductance compensation type global linear eccentricity for acquiring a power flow of a DC power network comprises:

Establishing an equal-conductance compensation global linear relationship of the node injection power with respect to the node translation voltage according to the known node load parameter and the node power parameter in the DC power network;

Establishing an equal-conductance compensation global linear eccentricity model of the tidal current in the DC power network according to the equal-conductance compensation global linear relationship and the known reference node number;

According to the equal-conductance compensation type global linear eccentricity model, an inverse matrix is used to establish an equivalent-conductance-compensated global linear eccentric matrix relation of the non-reference node translation voltage with respect to the non-reference node injection power;

Calculating a voltage value of each node in the DC power network and a transmission power value of each branch according to the equal-conductance compensation type global linear eccentric matrix relationship and the known reference node translation voltage value.
An equal-conductance compensation type global linear eccentricity method for acquiring a power flow of a DC power network according to claim 1, wherein said node injection power is established according to a node load parameter and a node power parameter in a known DC power network. The equivalent conductance compensation global linear relation of the node translation voltage is as follows:

The equal-conductance compensation global linear relation 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; υ i0 is the base point translation voltage of the node i, and is the target voltage after translation -1.0; υ i is the translation voltage of the node i; υ k is the node k The voltage is translated, and both υ i and υ k are the target voltages after translation -1.0.
The method according to claim 1, wherein the equal-conductance compensation type global linear eccentricity method is configured to establish a DC according to the equal-conductance compensation type global linear relationship and a known reference node number. The equivalent conductance compensation global linear eccentricity model for power flow in a power network is as follows:

An equal-conductance compensation global linear eccentricity model for tidal currents in a DC power network is established according to the following relationship:

Where P G1 is the power supply power of node 1; P Gi is the power supply power of node i; P Gn-1 is the power supply power of node n-1; P D1 is the load power of the node 1; P Di is the node The load power of i; P Dn-1 is the load power of the node n-1; j is the number of nodes in the DC power network, and belongs to the set of continuous 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; υ i0 is the node i Base point translation voltage, and is the standard value voltage after translation -1.0; n is the total number of nodes in the DC power network; the node numbered n is a known reference node; (G ij ) is the deletion reference An equal-conductance compensated node conductance matrix of the DC power network after the row and column of the node, the dimension of the isometric conductance-compensated node conductance matrix is (n-1)×(n-1); G ij is An element of the i-th row and the j-th column of the equal-conductance-compensated node conductance matrix (G ij ); υ 1 is a translation voltage of the node 1; υ i is a translation voltage of the node i; υ n-1 is The translation voltage of the node n-1, and the υ 1 , the υ i , and the υ n-1 are both standard value voltages after the translation of -1.0.
The equal-conductance compensation type global linear eccentricity method for acquiring a power flow of a DC power network according to claim 1, wherein the non-reference node translation is established by using an inverse matrix according to the global linear eccentricity model of the equal-conductance compensation type The equivalent-conductance-compensated global linear eccentric matrix relationship of the voltage with respect to the non-reference node injection power is as follows:

The equal-conductance-compensated global linear eccentric matrix relation of the non-reference node translation voltage with respect to the non-reference node injection power is established according to the following relationship:

Wherein, (G ij ) -1 is an inverse matrix of an equal-conductance compensation type node conductance matrix (G ij ) of the DC power network; P G1 is a power supply power of the node 1; P Gi is a power supply power of the node i; Gn-1 is the power of the node n-1; P D1 is the load power of the node 1; P Di is the load power of the node i; P Dn-1 is the load power of the node n-1; 1 is the translation voltage of the node 1; υ i is the translation voltage of the node i; υ n-1 is the translation voltage of the node n-1, and the υ 1 , the υ i and the υ N-1 is the standard value voltage after translation -1.0.
The equal-conductance compensation type global linear eccentricity method for acquiring a power flow of a DC power network according to claim 1, wherein said global linear eccentric matrix relationship according to said equal-conductance compensation type and a known reference node translation The voltage value is calculated by calculating the voltage value of each node in the DC power network and the transmission power value of each branch:

Calculating a non-reference node translation voltage value according to the equal-conductance compensation type global linear eccentric matrix relation;

Calculating, according to the known reference node translation voltage values, the non-reference node voltage value, the reference node voltage value, and each branch transmission power value in the DC power network according to the following three relations:

V i =1+υ i +υ n

V n =1+υ n

P ij =g ij (υ i -υ j )

Wherein, V i is the non-reference node voltage value, i=1, 2, . . . , n-1; V n is the reference node voltage value; υ n is the reference node translation voltage value, and is translation- The threshold voltage after 1.0; υ i is the translation voltage of node i; υ j is the translation voltage of node j, and both υ i and υ j are the standard value voltage after translation -1.0; g ij Is the conductance of the branch ij connected between the node i and the node j; P ij is the branch ij transmission power value.