A method and system for eliminating new energy power system node voltage out-of-limit

Abstract

The application discloses a kind of methods and systems for eliminating new energy power system node voltage out of limit, belong to power system technical field.The method of the application, comprising: according to the influence factor from the transmission line that can be broken, the first transmission line breaking scheme is evaluated;According to the size of the effectiveness, the first transmission line breaking scheme is further evaluated, and the transmission line breaking scheme that meets the requirement in the first transmission line breaking scheme is used as the second transmission line breaking scheme;According to quality index, the transmission line breaking scheme that meets the quality index in the second transmission line breaking scheme is obtained, and the transmission line breaking scheme is used as the third transmission line breaking scheme to eliminate the voltage out of limit of new energy power system node.The present application has small amount of calculation, high precision, strong applicability, and can be widely applied to actual power grid to solve related problems.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, and more particularly, to a method and system for eliminating over-limit of node voltage of new energy power system. BACKGROUND

[0002] Over-limit of voltage occurs in actual operation of high-proportion new energy power system. Once corresponding control measures are not taken in time, it is very likely to cause DC commutation failure, DC blocking, and even new energy off-grid, which seriously affects the safe and stable operation of power grid, and even leads to blackout. Compared with related measures for over-limit of voltage of traditional control node, the related influence factors and indexes constructed based on system admittance matrix in the present application are more accurate, and the solution has certain advantages in economy, response speed, and operation convenience, and can solve the problem that existing related technologies cannot effectively balance the relationship between calculation accuracy and calculation efficiency. SUMMARY

[0003] In view of the above problems, the present application provides a method for eliminating over-limit of node voltage of new energy power system, comprising:

[0004] determining an influence factor of node voltage change after opening of a transmission line of the high-proportion new energy power system, and evaluating a first transmission line opening scheme from the transmission lines that can be opened according to the influence factor;

[0005] determining a voltage change amount of the node after opening of the transmission line of the high-proportion new energy power system, determining the effectiveness of the first transmission line opening scheme according to the voltage change amount of the node, and further evaluating the first transmission line opening scheme according to the effectiveness to give a second transmission line opening scheme;

[0006] determining a quality index of the scheme for eliminating over-limit of node voltage, evaluating whether the second transmission line opening scheme can eliminate over-limit of node voltage of the new energy power system according to the quality index, and if so, taking the transmission line scheme meeting the requirements of the second transmission line opening scheme as a third transmission line opening scheme to eliminate over-limit of node voltage of the new energy power system.

[0007] Optionally, the calculation formula of the influence factor of node voltage change is as follows:

[0008]

[0009] wherein, x km is the reactance value on the transmission line k-m; G ik , B ik are the real part and imaginary part of the element value of the i-th row and k-th column in the system admittance matrix, respectively, G im , Bim Let g be the real part and the imaginary part of the element in the i-th row and m-th column of the system admittance matrix, respectively. ik b ik These are the real and imaginary parts of the admittance value on the transmission line km, respectively, with a1, a2, a3, and a4 being variables.

[0010] Optionally, the formula for the voltage change at the node is as follows:

[0011]

[0012] in, For reactive power flow over a transmission line of km; For reactive power flow losses along a transmission line of km; U k U m These are the voltage values ​​at nodes k and m, respectively; ΔB km θ is the difference between the susceptance value on the transmission line (km) and the grounding capacitance susceptance value; km Let f1, f2, f3, f4, f5, f6, and f7 be the voltage phase angles on the transmission line km, and f1, f2, f3, f4, f5, f6, and f7 be variables.

[0013] Optionally, the formulas for calculating quality indicators are as follows:

[0014]

[0015] in, These are the upper and lower voltage limits for node i, respectively; Let be the voltage value at node i after the transmission line km is disconnected.

[0016] This invention also proposes a system for eliminating node voltage over-limits in new energy power systems, comprising:

[0017] The first calculation unit determines the impact factors of the node voltage change caused by the disconnection of the transmission line of the high-proportion new energy power system, and evaluates the first transmission line disconnection scheme from the transmission lines that can be disconnected based on the impact factors.

[0018] The second calculation unit determines the voltage change at the nodes after the transmission lines of the high-proportion new energy power system are disconnected. Based on the voltage change at the nodes, it determines the effectiveness of the first transmission line disconnection scheme and further evaluates the first transmission line disconnection scheme based on the effectiveness, and then provides a second transmission line disconnection scheme.

[0019] The third calculation unit determines a quality index of the scheme for eliminating the node voltage out-of-limit, and determines whether the second transmission line opening scheme can eliminate the voltage out-of-limit of the node of the new energy power system according to the quality index, and if yes, the transmission line scheme meeting the requirement of the second transmission line opening scheme is taken as a third transmission line opening scheme to eliminate the voltage out-of-limit of the node of the new energy power system.

[0020] Optionally, the calculation formula of the influence factor of the node voltage change is as follows:

[0021]

[0022] Wherein, x km is the reactance value on the transmission line k-m; G ik , B ik are respectively the real part and the imaginary part of the element value of the i-th row and the k-th column in the system admittance matrix, G im , B im are respectively the real part and the imaginary part of the element value of the i-th row and the m-th column in the system admittance matrix, g ik , b ik are respectively the real part and the imaginary part of the admittance value on the transmission line k-m, a1, a2, a3, a4 are variables.

[0023] Optionally, the formula of the voltage change of the node is as follows:

[0024]

[0025] Wherein, is the reactive power flow on the transmission line k-m; is the reactive power flow lost on the transmission line k-m; U k , U m are respectively the voltage values on the nodes k and m; ΔB km is the difference between the susceptance value on the transmission line k-m and the ground capacitance susceptance value; θ km is the voltage phase angle on the transmission line k-m, f1, f2, f3, f4, f5, f6, f7 are variables.

[0026] Optionally, the calculation formula of the quality index is as follows:

[0027]

[0028] Wherein, are respectively the upper and lower limits of the voltage of the node i; is the voltage value of the node i after the transmission line k-m is opened.

[0029] The application can provide a group of high-quality solutions based on the transmission line opening measures for the node voltage out-of-limit problem frequently occurring in the actual power grid operation.

[0030] The present application combines linear methods and nonlinear methods under the premise of comprehensively considering factors such as economy, response speed, and operation convenience, constructs more accurate indexes such as influence factors and voltage variation based on a system admittance matrix, and effectively solves the problem that calculation efficiency and calculation accuracy cannot be considered in the prior art.

[0031] The present application has small calculation amount, high precision, and strong applicability, and can be widely applied to actual power grids to solve related problems. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a flowchart of the method of the present application;

[0033] Figure 2 is a structural diagram of the system of the present application. DETAILED DESCRIPTION

[0034] Reference will now be made to the drawings to describe the exemplary embodiments of the present application in detail. The present application can be implemented in various forms, and is not limited to the embodiments described herein, which are provided to fully and completely disclose the present application and to fully convey the scope of the present application to those skilled in the art. The terms used in the exemplary embodiments represented in the drawings are not limitations of the present application. In the drawings, the same elements / elements are denoted by the same reference numerals.

[0035] Unless otherwise defined, the terms used herein (including technical terms) have meanings commonly understood by those skilled in the art. In addition, it is to be understood that the terms defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense.

[0036] The present application proposes a method for eliminating node voltage out-of-limit of a new energy power system, as shown in Figure 1 The method comprises the following steps:

[0037] An influence factor of node voltage variation after disconnection of a transmission line of a high-proportion new energy power system is determined, and a first transmission line disconnection scheme is evaluated from the transmission lines that can be disconnected according to the influence factor;

[0038] A voltage variation of a node after disconnection of a transmission line of a high-proportion new energy power system is determined, the effectiveness of the first transmission line disconnection scheme is determined according to the voltage variation of the node, and the first transmission line disconnection scheme is further evaluated according to the effectiveness, and a second transmission line disconnection scheme is given;

[0039] Determine the quality indicators of the scheme to eliminate the voltage over-limit at the node. Based on the quality indicators, evaluate whether the second transmission line interruption scheme can eliminate the voltage over-limit at the node of the new energy power system. If so, use the transmission line interruption scheme that meets the requirements of the second transmission line interruption scheme as the third transmission line interruption scheme to eliminate the voltage over-limit at the node of the new energy power system.

[0040] The formula for calculating the influence factor of node voltage variation is as follows:

[0041]

[0042] Where, x km G represents the reactance value on the transmission line (km). ik B ik G represents the real and imaginary parts of the element in the i-th row and k-th column of the system admittance matrix, respectively. im B im Let g be the real part and the imaginary part of the element in the i-th row and m-th column of the system admittance matrix, respectively. ik b ik These are the real and imaginary parts of the admittance value on the transmission line km, respectively, with a1, a2, a3, and a4 being variables.

[0043] The formula for the voltage change at the node is as follows:

[0044]

[0045] in, For reactive power flow over a transmission line of km; For reactive power flow losses on a transmission line of km; U k U m These are the voltage values ​​at nodes k and m, respectively; ΔB km θ is the difference between the susceptance value on the transmission line (km) and the grounding capacitance susceptance value; km Let f1, f2, f3, f4, f5, f6, and f7 be the voltage phase angles on the transmission line km, and f1, f2, f3, f4, f5, f6, and f7 be variables.

[0046] The formulas for calculating the quality indicators are as follows:

[0047]

[0048] in, These represent the upper and lower voltage limits of node i, respectively; Let be the voltage value at node i after the transmission line km is disconnected.

[0049] The present invention will be further described below with reference to embodiments:

[0050] like Figure 1 As shown, the steps of an embodiment of the present invention are as follows:

[0051] Definition is the influence factor of the voltage variation of node i caused by the disconnection of transmission line k-m, then

[0052]

[0053] wherein x km is the reactance value on transmission line k-m; G ik , B ik and similar variables are respectively the real part and the imaginary part of the element value in the i-th row and k-th column of the system admittance matrix, G im , B im are respectively the real part and the imaginary part of the element value in the i-th row and m-th column of the system admittance matrix, g ik , b ik are respectively the real part and the imaginary part of the admittance value on transmission line k-m, and the variables a1, a2, a3, a4 can be obtained by the following formulae:

[0054]

[0055] wherein G kk , B kk and similar variables are respectively the real part and the imaginary part of the element value in the k-th row and k-th column of the system admittance matrix, G mm , B mm are respectively the real part and the imaginary part of the element value in the m-th row and m-th column of the system admittance matrix.

[0056] Based on the calculated value, a first transmission line disconnection scheme is evaluated from a plurality of disconnectable transmission lines.

[0057] The voltage variation of node i after the disconnection of transmission line k-m is defined as

[0058]

[0059] wherein is the reactive power flow on transmission line k-m; is the reactive power flow lost on transmission line k-m; ΔB km is the difference between the susceptance value on transmission line k-m and the ground capacitance susceptance value; θ km is the voltage phase angle on transmission line k-m; and the variables f1, f2, f3, f4, f5, f6, f7 can be obtained by the following formulae:

[0060]

[0061] wherein G mk , B mk ​and are respectively the real and imaginary parts of the value of the element in the mth row and kth column of the system admittance matrix.

[0062] The voltage variation of node i caused by the disconnection of transmission line k-m is calculated based on formula (3) The effectiveness of the first transmission line disconnection scheme is determined based on the value, and the first transmission line disconnection scheme is further evaluated according to the effectiveness, and a second transmission line disconnection scheme is given.

[0063] A scheme quality index δ for eliminating the node voltage out-of-limit problem is defined as follows:

[0064]

[0065] In the formula, and are respectively the upper and lower limits of the voltage of node i. In the formula, and are respectively the upper and lower limits of the voltage of node i. is the voltage value of node i after the disconnection of transmission line k-m.

[0066] Whether the second transmission line disconnection scheme can eliminate the voltage out-of-limit of the node of the new energy power system is evaluated based on the Newton-Raphson method, and if yes, a transmission line scheme in the second transmission line disconnection scheme that meets the requirements is evaluated as a third transmission line disconnection scheme to eliminate the voltage out-of-limit problem of the node of the new energy power system according to formula (5).

[0067] Application scenario:

[0068] The upper and lower limits of the voltage of node 26 are respectively set to 1.0494 p.u. and 0.94 p.u., and the voltage limit values of other nodes are 0.94-1.060 p.u. The current system operation condition is evaluated through power flow calculation, and it is found that the voltage of node 26 reaches 1.0526 p.u., and the voltage out-of-limit occurs. A set of transmission line disconnection schemes that can effectively eliminate the voltage out-of-limit problem of node 26 are given based on the method.

[0069] Table 1

[0070]

[0071] As can be seen from Table 1, the method provides transmission line disconnection schemes that can effectively eliminate the voltage out-of-limit problem of node 26, i.e., 28-29, 26-29, 26-28, 21-22 and 2-3.

[0072] The application further provides a system 200 for eliminating the voltage out-of-limit of a node of a new energy power system, as shown in Figure 2 The system comprises:

[0073] The first calculation unit 201 determines an influence factor of voltage variation of a node after disconnection of a transmission line of a high-proportion new energy power system, and evaluates a first transmission line disconnection scheme from the transmission lines that can be disconnected according to the influence factor.

[0074] The second calculation unit 202 determines a voltage variation of a node after disconnection of a transmission line of a high-proportion new energy power system, determines a size of effectiveness of the first transmission line disconnection scheme according to the voltage variation of the node, further evaluates the first transmission line disconnection scheme according to the size of the effectiveness, and gives a second transmission line disconnection scheme.

[0075] The third calculation unit 203 determines a quality index of a scheme for eliminating voltage out-of-limit of a node, determines whether the second transmission line disconnection scheme can eliminate voltage out-of-limit of a node of a new energy power system according to the quality index, and if yes, takes the transmission line scheme meeting the requirements of the second transmission line disconnection scheme as a third transmission line disconnection scheme to eliminate voltage out-of-limit of a node of a new energy power system.

[0076] The calculation formula of the influence factor of voltage variation of a node is as follows:

[0077]

[0078] Wherein, x km is the reactance value on the transmission line k-m; G ik and B ik are respectively the real part and the imaginary part of the element value of the i-th row and the k-th column of the system admittance matrix, G im and B im are respectively the real part and the imaginary part of the element value of the i-th row and the m-th column of the system admittance matrix, g ik and b ik are respectively the real part and the imaginary part of the admittance value on the transmission line k-m, and a1, a2, a3 and a4 are variables.

[0079] The formula of the voltage variation of a node is as follows:

[0080]

[0081] Wherein, is the reactive power flow on the transmission line k-m; is the reactive power flow lost on the transmission line k-m; U k and U m are respectively the voltage values on the nodes k and m; ΔB km is the difference between the susceptance value on the transmission line k-m and the ground capacitance susceptance value; θ km is the voltage phase angle on the transmission line k-m, and f1, f2, f3, f4, f5, f6 and f7 are variables.

[0082] wherein the calculation formula of the quality index is as follows:

[0083]

[0084] wherein, respectively represent the upper and lower limits of the voltage of node i; is the voltage value of node i after the opening of transmission line k-m.

[0085] The application can provide a set of high-quality solutions based on the opening of transmission lines for the node voltage out-of-limit problem often occurring in actual power grid operation.

[0086] The application combines linear methods and nonlinear methods under the premise of comprehensively considering factors such as economy, response speed, and operation convenience, constructs more accurate indexes such as influence factors and voltage change based on the system admittance matrix, and effectively solves the problem that the calculation efficiency and calculation accuracy cannot be considered in the prior art.

[0087] The application has small calculation amount, high precision, and strong applicability, and can be widely applied to actual power grids to solve related problems.

[0088] Those skilled in the art should understand that the embodiments of the application can be provided as a method, a system, or a computer program product. Therefore, the application can adopt a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the application can adopt the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes. The solutions in the embodiments of the application can be implemented in various computer languages, for example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript.

[0089] The application is described with reference to flowcharts and / or block diagrams according to the methods, devices (systems), and computer program products of the embodiments of the application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to produce a machine, so that the instructions executed by the computer or other programmable data processing devices produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The device that implements the functions specified in one flow or multiple flows and / or blocks. Figure 1 The device that implements the functions specified in one flow or multiple flows and / or blocks.

[0090] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the block or blocks.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that are executed on the computer or other programmable apparatus provide steps for implementing the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the block or blocks.

[0092] Although preferred embodiments of the application have been described herein, substitutions and alterations can be made to these embodiments by those skilled in the art without departing from the spirit and scope of the application. Accordingly, it is intended that the appended claims be interpreted as including all such alternatives and modifications as fall within the spirit and scope of the application.

[0093] It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1.A method for eliminating over-limit of node voltage in a new energy power system, the method comprising: determining an influence factor of node voltage change after disconnection of a transmission line in a new energy power system with a high proportion of new energy, and evaluating a first transmission line disconnection scheme from the transmission lines that can be disconnected according to the influence factor; determining a voltage change amount of a node after disconnection of a transmission line in a new energy power system with a high proportion of new energy, and determining the effectiveness of the first transmission line disconnection scheme according to the voltage change amount of the node, and further evaluating the first transmission line disconnection scheme according to the effectiveness to give a second transmission line disconnection scheme; determining a quality index of a scheme for eliminating over-limit of node voltage, and determining whether the second transmission line disconnection scheme can eliminate over-limit of node voltage in a new energy power system according to the quality index, and if so, taking the second transmission line disconnection scheme as a third transmission line disconnection scheme to eliminate over-limit of node voltage in a new energy power system; a calculation formula of the influence factor of node voltage change is as follows: wherein x km is the reactance value on the transmission line k-m; G ik , B ik are the real and imaginary parts of the value of the element in the i-th row and k-th column of the system admittance matrix, respectively, G im , B im are the real and imaginary parts of the value of the element in the i-th row and m-th column of the system admittance matrix, respectively, and a1, a2, a3, a4 are variables. wherein: a1, a2, a3, and a4 can be obtained by the following formula: wherein G kk , B kk are the real and imaginary parts of the value of the element in the kth row and kth column of the system admittance matrix, respectively, G mm , B mm are the real and imaginary parts of the value of the element in the mth row and mth column of the system admittance matrix, respectively, B km is the real and imaginary parts of the value of the element in the kth row and mth column of the system admittance matrix, b km and g km are the real and imaginary parts of the value of the admittance on the transmission line k-m. 2.The method according to claim 1, wherein a formula of the voltage change amount of the node is as follows: wherein, is the reactive power flow on the transmission line k-m; is the reactive power flow lost on the transmission line k-m; U k , U m are the voltage values at nodes k, m, respectively; ΔB km is the susceptance value on the transmission line k-m minus the ground capacitance susceptance value; θ km is the voltage phase angle on the transmission line k-m, and f1, f2, f3, f4, f5, f6, f7 are variables. 3.The method according to claim 1, wherein a calculation formula of the quality index is as follows: wherein Vi, max, min, respectively the upper and lower voltage limits of node i; Vi, k-m the voltage value of node i after the opening of the transmission line k-m. 4.A system for eliminating over-limit of node voltage in a new energy power system, the system comprising: a first calculation unit for determining an influence factor of node voltage change after disconnection of a transmission line in a new energy power system with a high proportion of new energy, and evaluating a first transmission line disconnection scheme from the transmission lines that can be disconnected according to the influence factor; a second calculation unit for determining a voltage change amount of a node after disconnection of a transmission line in a new energy power system with a high proportion of new energy, and determining the effectiveness of the first transmission line disconnection scheme according to the voltage change amount of the node, and further evaluating the first transmission line disconnection scheme according to the effectiveness to give a second transmission line disconnection scheme; a third calculation unit for determining a quality index of a scheme for eliminating over-limit of node voltage, and determining whether the second transmission line disconnection scheme can eliminate over-limit of node voltage in a new energy power system according to the quality index, and if so, taking the second transmission line disconnection scheme as a third transmission line disconnection scheme to eliminate over-limit of node voltage in a new energy power system; a calculation formula of the influence factor of node voltage change is as follows: wherein x km is the reactance value on the transmission line k-m; G ik , B ik are the real and imaginary parts of the element value in the i-th row and k-th column of the system admittance matrix, G im , B im are the real and imaginary parts of the element value in the i-th row and m-th column of the system admittance matrix, and a1, a2, a3, a4 are variables. wherein: a1, a2, a3, and a4 can be obtained by the following formula: where G kk and B kk are the real and imaginary parts of the element value in the kth row and kth column of the system admittance matrix, respectively, G mm and B mm are the real and imaginary parts of the element value in the mth row and mth column of the system admittance matrix, respectively, B km is the real and imaginary parts of the element value in the kth row and mth column of the system admittance matrix, b km and g km are the real and imaginary parts of the admittance value on the transmission line k-m. 5.The system according to claim 4, wherein a formula of the voltage change amount of the node is as follows: wherein is the reactive power flow on the transmission line k-m; is the reactive power flow lost on the transmission line k-m; U k , U m are the voltage values at nodes k, m, respectively; ΔB km is the susceptance value on the transmission line k-m minus the ground capacitance susceptance value; θ km is the voltage phase angle on the transmission line k-m, and f1, f2, f3, f4, f5, f6, f7 are variables. 6.The system according to claim 4, wherein a calculation formula of the quality index is as follows: wherein Vi, max and Vi, min are the upper and lower voltage limits of node i, respectively; Vi, k-m is the voltage value of node i after the disconnection of transmission line k-m.

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