Power flow calculation method, system and device based on voltage constraint and reactive power constraint

Abstract

The application relates to a power flow calculation method, system and equipment based on voltage constraints and reactive power constraints, which comprises the following steps: acquiring each node and parameter data of each node of a power system, constructing an active power balance equation and a reactive power balance equation of the power system according to the parameter data; constructing a power flow model according to the voltage constraints, the reactive power constraints, the active power balance equation and the reactive power balance equation, and converting inequality equations of the power flow model into equality constraint equations by using a transformation function mode; constructing a dynamic system model according to the equality constraint equations and equality equations of the power flow model; and solving the dynamic system model by using an integral mode to obtain parameter variable data based on that the power system is at an equilibrium point. The method is to construct a dynamic system model based on the voltage constraints and the reactive power constraints in the power flow model, and to calculate a solution meeting the requirements of the power system through the dynamic system model, so that the calculation efficiency and the convergence of the calculation process are improved.

Description

Technical Field

[0001] This application relates to the field of power system technology, and in particular to a power flow calculation method, system and equipment based on voltage constraints and reactive power constraints. Background Technology

[0002] Power flow calculation is a fundamental method for analyzing electrical quantity data in power systems. For a power system with n nodes, the power flow equations consist of 2n real equations, but with 4n variables, meaning each node has four variables: active power P, reactive power Q, voltage magnitude V, and voltage phase angle θ. When solving the power flow equations, two variables must be set as constants, leaving only two as variables to be solved. Depending on the given constants, nodes can be classified as PQ nodes, PV nodes, and θV nodes (also called slack nodes, where the voltage phase angle is zero and the voltage magnitude is a given constant). Under these boundary value conditions, the calculated power flow equations only represent a mathematical solution. The V value of the PQ node may not satisfy the voltage constraint, and the Q value of the PV node may not satisfy the reactive power constraint. In such cases, it is common practice to modify the given values ​​of some variables or change the node type (performing a PV-PQ node type conversion) and then recalculate the power flow equations to ensure that the solution satisfies the voltage and reactive power constraints. This method may cause numerical oscillations, leading to non-convergence of power flow calculations, or causing the power flow to converge to a solution that does not satisfy voltage and reactive power constraints, thus requiring readjustment of the given values ​​and repeated calculations, resulting in low computational efficiency. Summary of the Invention

[0003] This application provides a power flow calculation method, system, and device based on voltage constraints and reactive power constraints, which solves the technical problems of non-convergence and low computational efficiency in existing power flow equation calculation methods for power systems.

[0004] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0005] A power flow calculation method based on voltage constraints and reactive power constraints includes the following steps:

[0006] The active power balance equation and reactive power balance equation of the power system are constructed based on the parameter data of each node of the power system. The parameter data includes the PQ node set, the PV node set, and the equivalent conductance, equivalent admittance, active load, reactive load, voltage phase angle, voltage amplitude, active power output, and reactive power output of each node.

[0007] A power flow model is constructed based on voltage constraints, reactive power constraints, the active power balance equation, and the reactive power balance equation, and the inequality equations of the power flow model are converted into equality constraint equations using a transformation function method.

[0008] A dynamic system model is constructed based on the equality constraint equations and the equality equations of the power flow model.

[0009] The dynamic system model is solved by integration to obtain parameter variable data based on the dynamic power system being at the equilibrium point. The parameter variable data includes the voltage amplitude and voltage phase angle of the nodes.

[0010] Preferably, the power flow calculation method based on voltage constraints and reactive power constraints includes:

[0011] Substituting the parameter variable data into the system of equations of the dynamic system model, the numerical values ​​of the equations are obtained;

[0012] If the value of the equation function is 0, then the parameter variable data is the power flow solution of the power system under voltage and reactive power constraints.

[0013] If the value of the equation function is not 0, then the parameter variable data is the optimal power flow recovery solution of the power system under voltage and reactive power constraints.

[0014] Preferably, the optimal power flow recovery solution is an energy function H(·) of the power system. T The optimal power flow recovery solution with the minimum H(·) value, where H(·) is a system of equations. T Let H(·) be the transpose of H(·).

[0015] Preferably, the power flow model includes voltage constraints, reactive power constraints, active power balance equations, and reactive power balance equations, wherein the voltage constraint is V. i min ≤V i ≤V i max ,i∈N PQ The reactive power constraint is: The active power balance equation is as follows: The reactive power balance equation is as follows: In the formula, N PQ N is the set of PQ nodes; PV G is a set of PV nodes. ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let Q be the active load of node i. Li Let θ be the reactive load of node i.i Let θ be the voltage phase angle at node i. ij V is the phase angle difference between the voltage phase angles at node i and node j. i Let P be the voltage magnitude at node i. Gi Let Q be the active power output of node i. Gi V represents the reactive power output of node i. i min and V i max These are the lower limit and upper limit of the voltage amplitude at node i, respectively. i max This represents the upper limit of the reactive power output of node i.

[0016] Preferably, the equality constraint equation is:

[0017]

[0018]

[0019] In the formula, V i min and These are the lower limit and upper limit of the voltage amplitude at node i, respectively. N represents the upper limit of the reactive power output of node i. PQ N is the set of PQ nodes; PV Let Q be the set of PV nodes. Gi V represents the reactive power output of node i. i Let be the voltage amplitude at node i.

[0020] Preferably, the dynamic system model is as follows:

[0021]

[0022]

[0023] In the formula, H(·) is the system of equations, DH(·) is the Jacobian matrix of the system of equations H(·), and DH(·) is the function of the equations. T Let x be the transpose of DH(·), and let x be the parameter variable data to be solved. The derivative of x, N PQ N is the set of PQ nodes; PV G is a set of PV nodes. ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let Q be the active load of node i. Li Let θ be the reactive load of node i.i Let θ be the voltage phase angle at node i. ij V is the phase angle difference between the voltage phase angles at node i and node j. i Let P be the voltage magnitude at node i. Gi Let Q be the active power output of node i. Gi Let be the reactive power output of node i. and These are the lower limit and upper limit of the voltage amplitude at node i, respectively. i max This represents the upper limit of the reactive power output of node i.

[0024] This application also provides a power flow calculation system based on voltage constraints and reactive power constraints, including a balance equation construction module, a power flow model construction module, a dynamic model construction module, and a parameter solving module;

[0025] The balance equation construction module is used to acquire the various nodes of the power system and the parameter data of each node, and to construct the active power balance equation and reactive power balance equation of the power system based on the parameter data; the parameter data includes the PQ node set, the PV node set, and the equivalent conductance, equivalent admittance, active load, reactive load, voltage phase angle, voltage amplitude, active output power and reactive output power of each node.

[0026] The power flow model construction module is used to construct a power flow model based on voltage constraints, reactive power constraints, the active power balance equation, and the reactive power balance equation, and to convert the inequality equations of the power flow model into equality constraint equations using a transformation function.

[0027] The dynamic model construction module is used to construct a dynamic system model based on the equality constraint equations and the equality equations of the power flow model.

[0028] The parameter solving module is used to solve the dynamic system model using an integral method to obtain parameter variable data based on the dynamic power system being at an equilibrium point. The parameter variable data includes the voltage amplitude and voltage phase angle of the nodes.

[0029] Preferably, the power flow calculation system based on voltage and reactive power constraints includes a solution identification and judgment module. The solution identification and judgment module is used to substitute the parameter variable data into the system of equations of the dynamic system model to obtain the equation function values; and if the equation function value is 0, then the parameter variable data is the power flow solution of the power system under voltage and reactive power constraints, or if the equation function value is not 0, then the parameter variable data is the optimal recovery solution of the power flow under voltage and reactive power constraints.

[0030] Preferably, the power flow model includes voltage constraints, reactive power constraints, active power balance equations, and reactive power balance equations, wherein the voltage constraint is V. i min ≤V i ≤V i max ,i∈N PQ The reactive power constraint is: The active power balance equation is as follows: The reactive power balance equation is as follows:

[0031] The equality constraint equation is:

[0032]

[0033]

[0034] The dynamic system model is as follows:

[0035]

[0036]

[0037] In the formula, N PQ N is the set of PQ nodes; PV G is a set of PV nodes. ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let Q be the active load of node i. Li Let θ be the reactive load of node i. i Let θ be the voltage phase angle at node i. ij V is the phase angle difference between the voltage phase angles at node i and node j. i Let P be the voltage magnitude at node i. Gi Let Q be the active power output of node i. Gi Let be the reactive power output of node i. and These are the lower limit and upper limit of the voltage amplitude at node i, respectively. Let H(·) be the upper limit of reactive power output at node i, H(·) be the system of equations, and DH(·) be the Jacobian matrix of the system of equations H(·). T Let x be the transpose of DH(·), and let x be the parameter variable data to be solved. It is the derivative of x.

[0038] This application also provides a terminal device, including a processor and a memory;

[0039] The memory is used to store program code and transmit the program code to the processor;

[0040] The processor is configured to execute the power flow calculation method based on voltage constraints and reactive power constraints as described above, according to the instructions in the program code.

[0041] As can be seen from the above technical solutions, the embodiments of this application have the following advantages: The power flow calculation method, system, and device based on voltage constraints and reactive power constraints include: acquiring the various nodes of the power system and their parameter data; constructing the active power balance equation and reactive power balance equation of the power system based on the parameter data; constructing a power flow model based on voltage constraints, reactive power constraints, active power balance equation, and reactive power balance equation; converting the inequality equations of the power flow model into equality constraint equations using a transformation function; constructing a dynamic system model based on the equality constraint equations and the equality equations of the power flow model; and solving the dynamic system model using an integral method to obtain parameter variable data based on the dynamic power system at the equilibrium point. This power flow calculation method based on voltage constraints and reactive power constraints is a dynamic system model constructed by adding voltage constraints and reactive power constraints to the power flow model. It calculates solutions that meet the power system requirements through the dynamic system model, which not only improves computational efficiency but also improves the convergence of the computation process, solving the technical problems of non-convergence and low computational efficiency in existing power flow equation calculation methods. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart illustrating the steps of the power flow calculation method based on voltage constraints and reactive power constraints described in the embodiments of this application.

[0044] Figure 2 This is a wiring diagram of the 3-node power system described in the embodiments of this application;

[0045] Figure 3 This is a framework diagram of the power flow calculation system based on voltage constraints and reactive power constraints described in the embodiments of this application. Detailed Implementation

[0046] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] This application proposes a power flow calculation method, system, and device based on voltage and reactive power constraints, which solves the technical problems of non-convergence and low computational efficiency in existing power flow equation calculation methods for power systems. In the embodiments of this application, the power flow calculation method, system, and device based on voltage and reactive power constraints are described in detail using a 3-node power system as a specific example. Details of the power system's wiring can be found in [link to relevant documentation]. Figure 2 .exist Figure 2 In the diagram, node 1 is node θV, the voltage amplitude of node θV is V1 = 1.02pu, and the voltage phase angle of node θV is θ1 = 0. L1 Q is the active load at node θV. L1 Node θ is the reactive load at node θV; node 2 is a PV node with a voltage amplitude of V2 = 1p.u. and an active power P at node θV. G2 =100MW, P L2 Q represents the active load of the PV node. L2 Node 3 is the reactive load of the PV node; Node 4 is the PQ node, P... L3 Q represents the active load of node PQ. L3 The reactive load is for nodes P and Q. The load for each node is as follows: P L1 +Q L1 =150MW + 80MVar, P L2 +Q L2 =150MW + 70MVar, P L3 +Q L3 =50MW+30MVar. pu refers to the per-unit value of the corresponding electrical quantity. For example, the voltage amplitude V1 of node θV = 1.02pu means that the voltage amplitude V1 of node θV is 1.02 times the rated voltage of the power system.

[0048] Example 1:

[0049] Figure 1 This is a flowchart illustrating the steps of the power flow calculation method based on voltage constraints and reactive power constraints described in the embodiments of this application. Figure 2 This is a wiring diagram of a 3-node power system as described in an embodiment of this application.

[0050] like Figure 1 As shown, this application provides a power flow calculation method based on voltage constraints and reactive power constraints, including the following steps:

[0051] S10. Obtain the data of each node in the power system and its parameters, and construct the active power balance equation and reactive power balance equation of the power system based on the parameter data. The parameter data includes the PQ node set, the PV node set, and the equivalent conductance, equivalent admittance, active load, reactive load, voltage phase angle, voltage amplitude, active power output, and reactive power output of each node.

[0052] It should be noted that step S10 mainly involves acquiring information about each node in the power system, as well as the type of each node and its equivalent conductance, equivalent admittance, active load, reactive load, voltage phase angle, voltage amplitude, active power output, and reactive power output. In this embodiment, the node types include PV nodes, PQ nodes, and θV nodes.

[0053] Furthermore, for PQ nodes and PV nodes, the active power balance equation of the power system is:

[0054] For nodes PQ, the reactive power balance equation of the power system is: In the formula, N PQ N is the set of PQ nodes; PV G is a set of PV nodes. ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let Q be the active load of node i. Li Let θ be the reactive load of node i. i Let θ be the voltage phase angle at node i. ij V is the phase angle difference between the voltage phase angles at node i and node j. i Let P be the voltage magnitude at node i. Gi Let Q be the active power output of node i. Gi Let be the reactive power output of node i.

[0055] S20. Construct a power flow model based on voltage constraints, reactive power constraints, active power balance equations, and reactive power balance equations, and use transformation functions to convert the inequality equations of the power flow model into equality constraint equations.

[0056] It should be noted that in step S20, the first step is to construct a power flow model; the second step is to convert the inequality equations in the power flow model into equality constraint equations.

[0057] Furthermore, the power flow model includes voltage constraints, reactive power constraints, active power balance equations, and reactive power balance equations, with the voltage constraint being V.i min ≤V i ≤V i max ,i∈N PQ The reactive power constraint is: The active power balance equation is: The reactive power balance equation is: In the formula, N PQ N is the set of PQ nodes; PV G is a set of PV nodes. ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let Q be the active load of node i. Li Let θ be the reactive load of node i. i Let θ be the voltage phase angle at node i. ij V is the phase angle difference between the voltage phase angles at node i and node j. i Let P be the voltage magnitude at node i. Gi Let Q be the active power output of node i. Gi V represents the reactive power output of node i. i min and V i max These are the lower limit and upper limit of the voltage amplitude at node i, respectively. This represents the upper limit of the reactive power output of node i.

[0058] It should be noted that, under voltage constraints, for the constructed power flow model to meet the needs of the actual power system, the voltage amplitude of the PQ node must be maintained within an acceptable range in the power system.

[0059] In this embodiment, the transformation function ψ(x) is x is a variable in the transformation function. The voltage is constrained to V according to the transformation function. i min ≤V i ≤V i max ,i∈N PQ The reactive power constraint is: After transformation, the equality constraint equation is obtained as follows:

[0060]

[0061]

[0062] In the formula, and These are the lower limit and upper limit of the voltage amplitude at node i, respectively. N represents the upper limit of the reactive power output of node i. PQ N is the set of PQ nodes; PV Let Q be the set of PV nodes. Gi V represents the reactive power output of node i. i Let be the voltage amplitude at node i.

[0063] S30. Construct a dynamic system model based on the equality constraint equations and the equality equations of the power flow model.

[0064] It should be noted that in step S30, the dynamic system model is mainly composed of the set of equation functions based on the equality constraint equations, active power balance equations and reactive power balance equations obtained in steps S10 and S20.

[0065] Furthermore, the dynamic system model is as follows:

[0066]

[0067]

[0068] In the formula, H(·) is the system of equations, DH(·) is the Jacobian matrix of the system of equations H(·), and DH(·) is the function of the equations. T Let x be the transpose of DH(·), and let x be the parameter variable data to be solved. The derivative of x, N PQ N is the set of PQ nodes; PV G is a set of PV nodes. ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let QLi be the active load at node i, QLi be the reactive load at node i, and θ be the reactive load at node i. i Let θ be the voltage phase angle at node i. ij V is the phase angle difference between the voltage phase angles at node i and node j. i Let P be the voltage magnitude at node i. Gi Let Q be the active power output of node i. Gi Let be the reactive power output of node i. and These are the lower limit and upper limit of the voltage amplitude at node i, respectively. This represents the upper limit of the reactive power output of node i.

[0069] S40. Solve the dynamic system model using the integral method to obtain parameter variable data based on the dynamic power system at the equilibrium point. The parameter variable data includes the voltage magnitude and voltage phase angle of the nodes.

[0070] It should be noted that in step S40, the dynamic system model is mainly solved by integration.

[0071] In the embodiments of this application, such as Figure 2 As shown, with Figure 2 Using three nodes as an example, the dynamic system model of these three nodes is as follows:

[0072]

[0073]

[0074] In the formula, V3 is the voltage amplitude at node 3, θ2 is the voltage phase angle at node 2, and θ3 is the voltage phase angle at node 3. In a 3-node power system, and They are 0.9 PU and 1.1 PU respectively, Q i max The value is 200 MVar. Using the flat starting point of the equation system of the dynamic system model solved by Newton's method as the initial point, the equilibrium point of the dynamic system model with three nodes is obtained by integrating using a solver based on variable-order numerical differential formulas. This yields the parameter variable data based on the dynamic power system at its equilibrium point.

[0075] This application provides a power flow calculation method based on voltage and reactive power constraints. The method includes acquiring the parameters of each node in the power system; constructing active and reactive power balance equations based on the parameter data; building a power flow model based on voltage and reactive power constraints, the active and reactive power balance equations; converting the inequalities of the power flow model into equal constraint equations using transformation functions; constructing a dynamic system model based on the equal constraint equations and the equal equations of the power flow model; and solving the dynamic system model using integration to obtain parameter variable data based on the dynamic power system at its equilibrium point. This power flow calculation method based on voltage and reactive power constraints incorporates voltage and reactive power constraints into the power flow model to construct a dynamic system model. By calculating solutions that satisfy the power system's requirements through this dynamic system model, the method not only improves computational efficiency but also enhances the convergence of the calculation process, thus solving the technical problems of non-convergence and low computational efficiency in existing power flow equation calculation methods.

[0076] In one embodiment of this application, the power flow calculation method based on voltage constraints and reactive power constraints includes:

[0077] Substitute the parameter variable data into the system of equations of the dynamic system model to obtain the numerical values ​​of the equations;

[0078] If the value of the equation function is 0, then the parameter variable data is the power flow solution of the power system under voltage and reactive power constraints.

[0079] If the equation function value is not zero, then the parameter variable data represents the optimal power flow recovery solution of the power system under voltage and reactive power constraints. The optimal power flow recovery solution is an energy function H(·) of the power system. T The optimal power flow recovery solution with the minimum H(·) value, where H(·) is a system of equations. T Let H(·) be the transpose of H(·).

[0080] It should be noted that, as Figure 2 As shown, a 3-node power system is used as a specific example for detailed explanation, and the resulting equilibrium points are shown in Table 1 below:

[0081] Table 1

[0082] 6.2252 6.2259 0.9887

[0083] Substituting the equilibrium point into the system of equations of the dynamic system model, the equations satisfy the condition that the numerical value of the equations is 0. Therefore, the equilibrium point in Table 1 is the power flow solution of the 3-node power system considering voltage and reactive power constraints.

[0084] If the equation function value is not 0, to test the case where the boundary conditions are not suitable, modify the generator output and load of the 3-node generator by multiplying the original values ​​by 4.2, and simultaneously adjust Q. i max Increased to 500 MVar. Under this condition, the equilibrium points obtained by integration using a solver based on variable-order numerical differential formulas to calculate the dynamic system model are detailed in Table 2 below:

[0085] Table 2

[0086] 6.0207 6.0195 0.8967

[0087] As can be seen from Table 2, V3 is less than the lower limit of the voltage amplitude of 0.9 pu, which corresponds to the energy function H(·). T The optimal power flow recovery solution with the minimum H(·) value shows that the maximum unbalance quantity where the equation function value is not zero is the solution that minimizes the power flow. Therefore, to ensure that the power flow solution meets the voltage constraint conditions, the voltage value of V3 needs to be increased. This can usually be achieved by adjusting the voltage setpoint of the nearby PV nodes. Thus, by adjusting V2 from 1p.u. to 1.01pu, the power flow solution that meets both the voltage and reactive power constraints in Table 3 can be obtained by recalculating.

[0088] Table 3

[0089]

[0090]

[0091] This power flow calculation method based on voltage and reactive power constraints incorporates voltage and reactive power constraints during modeling, avoiding frequent PV-PQ node type conversions in power flow calculations. It solves the constructed dynamic system model through integration, combining with different efficient integration methods and nonlinear calculation techniques. This overcomes the potential singularity issues in Newton's method and improves the convergence of the calculations.

[0092] Example 2:

[0093] Figure 3 This is a framework diagram of the power flow calculation system based on voltage constraints and reactive power constraints described in the embodiments of this application.

[0094] like Figure 3 As shown, this application also provides a power flow calculation system based on voltage constraints and reactive power constraints, including a balance equation construction module 10, a power flow model construction module 20, a dynamic model construction module 30, and a parameter solving module 40;

[0095] The balance equation construction module 10 is used to obtain the various nodes of the power system and the parameter data of each node, and to construct the active power balance equation and reactive power balance equation of the power system based on the parameter data. The parameter data includes the PQ node set, the PV node set, and the equivalent conductance, equivalent admittance, active load, reactive load, voltage phase angle, voltage amplitude, active output power and reactive output power of each node.

[0096] The power flow model construction module 20 is used to construct a power flow model based on voltage constraints, reactive power constraints, active power balance equations and reactive power balance equations, and to convert the inequality equations of the power flow model into equal constraint equations using transformation functions.

[0097] The dynamic model construction module 30 is used to construct a dynamic system model based on the equality constraint equations and the equality equations of the power flow model.

[0098] The parameter solving module 40 is used to solve the dynamic system model using an integral method to obtain parameter variable data based on the dynamic power system at the equilibrium point. The parameter variable data includes the voltage magnitude and voltage phase angle of the nodes.

[0099] In this embodiment, the power flow calculation system based on voltage and reactive power constraints includes a solution identification and judgment module. The solution identification and judgment module is used to substitute the parameter variable data into the system of equations of the dynamic system model to obtain the equation function values. If the equation function value is 0, the parameter variable data is the power flow solution of the power system under voltage and reactive power constraints; if the equation function value is not 0, the parameter variable data is the optimal recovery solution of the power flow under voltage and reactive power constraints.

[0100] In this embodiment, the power flow model includes voltage constraints, reactive power constraints, active power balance equations, and reactive power balance equations, with the voltage constraint being V. i min ≤V i ≤V i max ,i∈N PQ The reactive power constraint is: The active power balance equation is: The reactive power balance equation is:

[0101] The equality constraint equation is

[0102]

[0103]

[0104] The dynamic system model is as follows:

[0105]

[0106]

[0107] In the formula, N PQ N is the set of PQ nodes; PV G is a set of PV nodes. ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let Q be the active load of node i. Li Let θ be the reactive load of node i. i Let θ be the voltage phase angle at node i. ij V is the phase angle difference between the voltage phase angles at node i and node j. i Let P be the voltage magnitude at node i. Gi Let Q be the active power output of node i. Gi V represents the reactive power output of node i. i min and These are the lower limit and upper limit of the voltage amplitude at node i, respectively. Let H(·) be the upper limit of reactive power output at node i, H(·) be the system of equations, and DH(·) be the Jacobian matrix of the system of equations H(·). T Let x be the transpose of DH(·), and let x be the parameter variable data to be solved. It is the derivative of x.

[0108] It should be noted that the content of the modules in Embodiment 2 corresponds to the steps in the method of Embodiment 1. The content of the steps in the method of Embodiment 1 has been described in detail in Embodiment 1, and the content of the modules in the system will not be described again in Embodiment 2.

[0109] Example 3:

[0110] This application also provides a terminal device, including a processor and a memory;

[0111] Memory is used to store program code and transfer the program code to the processor;

[0112] The processor is used to execute the power flow calculation method based on voltage constraints and reactive power constraints as described above, according to the instructions in the program code.

[0113] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0114] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0115] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0116] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0117] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0118] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A power flow calculation method based on voltage constraints and reactive power constraints, characterized in that, Includes the following steps: The active power balance equation and reactive power balance equation of the power system are constructed based on the parameter data of each node of the power system. The parameter data includes the PQ node set, the PV node set, and the equivalent conductance, equivalent admittance, active load, reactive load, voltage phase angle, voltage amplitude, active power output, and reactive power output of each node. A power flow model is constructed based on voltage constraints, reactive power constraints, the active power balance equation, and the reactive power balance equation, and the inequality equations of the power flow model are converted into equality constraint equations using a transformation function method. A dynamic system model is constructed based on the equality constraint equations and the equality equations of the power flow model. The dynamic system model is solved by integration to obtain parameter variable data based on the dynamic power system at the equilibrium point. The parameter variable data includes the voltage amplitude and voltage phase angle of the nodes. Substituting the parameter variable data into the system of equations of the dynamic system model, the numerical values ​​of the equations are obtained; If the value of the equation function is 0, then the parameter variable data is the power flow solution of the power system under voltage and reactive power constraints. If the value of the equation function is not 0, then the parameter variable data is the optimal power flow recovery solution of the power system under voltage and reactive power constraints. The equality constraint equation is: In the formula, V i min and V i max These are the lower limit and upper limit of the voltage amplitude at node i, respectively. i max N represents the upper limit of the reactive power output of node i. PQ N is the set of PQ nodes; PV Let Q be the set of PV nodes. Gi V represents the reactive power output of node i. i Let be the voltage amplitude at node i.

2. The power flow calculation method based on voltage constraints and reactive power constraints according to claim 1, characterized in that, The optimal power flow recovery solution is an energy function H(·) of the power system. T The optimal power flow recovery solution with the minimum H(·) value, where H(·) is a system of equations. T Let H(·) be the transpose of H(·).

3. The power flow calculation method based on voltage constraints and reactive power constraints according to claim 1, characterized in that, The power flow model includes voltage constraints, reactive power constraints, active power balance equations, and reactive power balance equations. The voltage constraints are: The reactive power constraint is: The active power balance equation is: The reactive power balance equation is: In the formula, N PQ N is the set of PQ nodes; PV G is a set of PV nodes. ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let Q be the active load of node i. Li Let θ be the reactive load of node i. i Let θ be the voltage phase angle at node i. ij V is the phase angle difference between the voltage phase angles at node i and node j. i Let P be the voltage magnitude at node i. Gi Let Q be the active power output of node i. Gi V represents the reactive power output of node i. i min and V i max These are the lower limit and upper limit of the voltage amplitude at node i, respectively. i max This represents the upper limit of the reactive power output of node i.

4. The power flow calculation method based on voltage constraints and reactive power constraints according to claim 1, characterized in that, The dynamic system model is as follows: In the formula, H(·) is the system of equations, DH(·) is the Jacobian matrix of the system of equations H(·), and DH(·) is the function of the equations. T Let x be the transpose of DH(·), and let x be the parameter variable data to be solved. The derivative of x, N PQ N is the set of PQ nodes; PV G is a set of PV nodes. ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let Q be the active load of node i. Li Let θ be the reactive load of node i. i Let θ be the voltage phase angle at node i. ij V is the phase angle difference between the voltage phase angles at node i and node j. i Let P be the voltage magnitude at node i. Gi Let Q be the active power output of node i. Gi V represents the reactive power output of node i. i min and V i max These are the lower limit and upper limit of the voltage amplitude at node i, respectively. i max This represents the upper limit of the reactive power output of node i.

5. A power flow calculation system based on voltage constraints and reactive power constraints, characterized in that, It includes a balance equation construction module, a power flow model construction module, a dynamic model construction module, a parameter solving module, and a solution identification and judgment module; The balance equation construction module is used to acquire the various nodes of the power system and the parameter data of each node, and to construct the active power balance equation and reactive power balance equation of the power system based on the parameter data; the parameter data includes the PQ node set, the PV node set, and the equivalent conductance, equivalent admittance, active load, reactive load, voltage phase angle, voltage amplitude, active output power and reactive output power of each node. The power flow model construction module is used to construct a power flow model based on voltage constraints, reactive power constraints, the active power balance equation, and the reactive power balance equation, and to convert the inequality equations of the power flow model into equality constraint equations using a transformation function. The dynamic model construction module is used to construct a dynamic system model based on the equality constraint equations and the equality equations of the power flow model. The parameter solving module is used to solve the dynamic system model using an integral method to obtain parameter variable data based on the dynamic power system being at an equilibrium point. The parameter variable data includes the voltage amplitude and voltage phase angle of the nodes. The solution identification and judgment module is used to substitute the parameter variable data into the system of equations of the dynamic system model to obtain the value of the equation function; and if the value of the equation function is 0, then the parameter variable data is the power flow solution of the power system under voltage constraints and reactive power constraints, or if the value of the equation function is not 0, then the parameter variable data is the optimal recovery solution of the power flow under voltage constraints and reactive power constraints. The equality constraint equation is: In the formula, V i min and V i max These are the lower limit and upper limit of the voltage amplitude at node i, respectively. i max N represents the upper limit of the reactive power output of node i. PQ N is the set of PQ nodes; PV Let Q be the set of PV nodes. Gi V represents the reactive power output of node i. i Let be the voltage amplitude at node i.

6. The power flow calculation system based on voltage constraints and reactive power constraints according to claim 5, characterized in that, The power flow model includes voltage constraints, reactive power constraints, active power balance equations, and reactive power balance equations. The voltage constraints are: The reactive power constraint is: The active power balance equation is: The reactive power balance equation is: ; The dynamic system model is as follows: In the formula, G ij B is the equivalent conductance between node i and node j. ij P is the equivalent susceptance between node i and node j. Li Let Q be the active load of node i. Li Let θ be the reactive load of node i. i Let θ be the voltage phase angle at node i. ij P is the phase angle difference between the voltage phase angles of node i and node j. Gi Let H(·) be the active power output at node i, H(·) be the system of equations, and DH(·) be the Jacobian matrix of the system of equations H(·). T Let x be the transpose of DH(·), and let x be the parameter variable data to be solved. It is the derivative of x.

7. A terminal device, characterized in that, Including processor and memory; The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute the power flow calculation method based on voltage constraints and reactive power constraints as described in any one of claims 1-4, according to the instructions in the program code.

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