Method, device, storage medium and equipment for judging static stability of power grid

Abstract

The present invention discloses a method, apparatus, storage medium, and equipment for determining the static stability of a power grid. Based on the structure of a DSSC and the operating principle of line power flow control performed by the DSSC, the present invention obtains a power flow equation for a power grid equipped with the DSSC. In the absence of any power grid scenario, power flow calculation and voltage-active power analysis are performed on the power flow equation to obtain a power grid static stability criterion. Based on a scenario where a single node in the power grid increases load, the power grid static stability is determined according to the power grid static stability criterion, thereby realizing a static stability determination method applicable to power grids containing DSSCs.

Description

Technical Field

[0001] The present invention relates to a method, device, storage medium and equipment for judging the static stability of a power grid, and belongs to the technical field of power systems. Background Art

[0002] With the passage of time, traditional energy structures are no longer adequate for sustainable development, and the utilization of renewable energy has become a key focus of current energy development. However, with the large-scale integration of renewable energy, the challenges of power flow control and flexible integration of large-capacity power sources are becoming increasingly prominent. Therefore, addressing the challenges of large power flow fluctuations and uneven distribution during renewable energy integration, which restrict power supply and reduce grid operational efficiency, has become a top priority.

[0003] With the rapid development of power electronics technology, Flexible Alternating Current Transmission Systems (FACTS) have been well applied and developed in the field of power transmission line flow control. Among them, the Distributed Static Series Compensator (DSSC) is a widely used distributed FACTS device. This FACTS device achieves similar functions to centralized FACTS devices by distributing a large number of small-power compensation devices on the transmission line and coordinating the operation of a large number of devices through a cluster control strategy, thereby achieving more economical installation costs and a shorter installation cycle. However, in order to solve the problem of static voltage stability of the power grid after the integration of new energy, the traditional method of judging the static stability of the power grid is no longer applicable to power grids containing DSSC. Summary of the Invention

[0004] The present invention provides a method, device, storage medium and equipment for judging the static stability of a power grid, which solve the problems disclosed in the background technology.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for determining the static stability of a power grid, comprising:

[0007] According to the structure of DSSC and the working principle of DSSC for line power flow control, the power flow equation of the power grid after the DSSC is installed is obtained; wherein the power grid is a power grid containing new energy;

[0008] In the absence of any power grid scenario, the power flow equation of the power grid equipped with DSSC is used to calculate the power flow and analyze the voltage and active power to obtain the static stability criterion of the power grid;

[0009] Based on the scenario of increasing the load at a single node in the power grid, the power flow equation of the power grid equipped with DSSC is used for power flow calculation and voltage and active power analysis to determine the voltage at the node in the power grid when the load increases to exceed the allowable value;

[0010] According to the voltage of the nodes in the power grid when the load increases to exceed the allowable value, the power flow equation of the power grid after loading the DSSC is calculated, and the static stability of the power grid is judged based on the calculation results and the static stability criterion of the power grid.

[0011] According to the structure of DSSC and the working principle of DSSC for line power flow control, the power flow equation of the power grid after DSSC is installed is obtained, including:

[0012] According to the structure of DSSC and the working principle of DSSC for line power flow control, the equivalent injection power of the node in the power grid after DSSC is installed is obtained;

[0013] According to the equivalent injected power of the nodes in the power grid after the DSSC is installed and the power grid power flow calculation equation, the power flow equation of the power grid after the DSSC is installed is obtained.

[0014] The ith node of line ij in the power grid is loaded with a DSSC. The equivalent injected power of the node in the power grid after loading the DSSC is:

[0015]

[0016]

[0017] P jD =U DSSC U j [gcos(δ D -δ j )-bsin(δ D -δ j )]

[0018] Q jD =-U DSSC U j [gsin(δ D -δ j )+bcos(δ D -δ j )]

[0019] Among them, line ij is the line between the i-th node and the j-th node in the power grid, P iD , Q iD are the equivalent injected active power and the equivalent injected reactive power of the i-th node after DSSC is installed, P jD , Q jDare the equivalent injected active power and reactive power of the jth node after DSSC is installed, U DSSC is the DSSC injection voltage, δ D For U DSSC Phase, U i , δ i are the voltage and phase angle of the i-th node, U j , δ j are the voltage and phase angle of the j-th node respectively;

[0020] parameter parameter R is the resistance part of the line ij impedance, X is the reactance part of the line ij impedance, b c is the parameter in the earth admittance.

[0021] In the power grid, the ith node of line ij is loaded with a DSSC. The power flow equation of the power grid after loading the DSSC is:

[0022]

[0023]

[0024]

[0025]

[0026] Among them, line ij is the line between the i-th node and the j-th node in the power grid, ΔP i , ΔQ i are respectively the active and reactive power injected into the i-th node, ΔP j , ΔQ j are the active and reactive power injected into the jth node, G ij 、B ij are the real and imaginary parts of the admittance of line ij, δ i 、U i are the phase angle and voltage of the i-th node, δ j 、U j are the phase angle and voltage of the jth node respectively, n is the number of nodes in the power grid, P iD , Q iD are the equivalent injected active power and reactive power of the i-th node after DSSC is installed, P jD , Q jD are the equivalent injected active power and the equivalent injected reactive power of the jth node after DSSC is installed, P i , Q i are respectively the active and reactive power of the i-th node, P j , Q jare the active and reactive power of the j-th node respectively.

[0027] Without any power grid scenario, the power flow equation of the power grid equipped with DSSC is used for power flow calculation and voltage and active power analysis to obtain the static stability criteria of the power grid, including:

[0028] In the absence of any power grid scenario, the power flow equation of the power grid equipped with DSSC is calculated to obtain the static voltage stability index of the power grid. The static voltage stability index is an indicator of the existence of a solution to the power flow equation.

[0029] In the absence of any power grid, the power flow equation of the power grid equipped with DSSC is analyzed for voltage and active power to obtain the margin index of the power grid's voltage and active power sensitivity. The margin index of the voltage and active power sensitivity is the distance from the current active power output of the power grid to the voltage collapse point in the power grid.

[0030] According to the static voltage stability index and the margin index of voltage active sensitivity, the static stability criterion of the power grid is obtained.

[0031] The static voltage stability index is:

[0032] S=E 4 -4E 2 (P′X′+Q′R′)-4(P′X′-Q′R′) 2

[0033] The margin index of voltage active sensitivity is:

[0034]

[0035] Among them, S is the static voltage stability index, P' and Q' are respectively the active power and reactive power output to the grid after the new energy is connected to the grid, R' is the resistance part of the impedance between the new energy grid connection point and the balance node, X' is the reactance part of the impedance between the new energy grid connection point and the balance node, E is the voltage amplitude of the balance point, K is the margin index of the voltage active sensitivity, P Now is the current active power output of new energy, P Max Make the greatest contribution to new energy.

[0036] The static stability criterion of the power grid is: S ≥ 0 and K < 0; among them, S ≥ 0 means that the calculation result of the power flow equation has a power flow solution, and K < 0 means that the current active power output of the power grid is not at the voltage collapse point.

[0037] Based on the scenario of increasing the load at a single node in the power grid, the power flow equation of the power grid equipped with DSSC is used for power flow calculation and voltage and active power analysis to determine the voltage at the node in the power grid when the load increases to exceed the allowable value, including:

[0038] 1) Under preset initial conditions, the power flow equation of the power grid after the DSSC is installed is calculated to obtain the power flow solution;

[0039] 2) Taking the power flow solution as the initial point, calculate the partial derivative of the voltage with respect to the active power at the initial point, and determine the direction of active voltage change based on the partial derivative;

[0040] 3) Select any node in the power grid as the target node, and increase the load of the target node by a preset step size along the direction of active voltage change to obtain a new load;

[0041] 4) Determine whether the new load exceeds the allowable value. If not, perform power flow calculation on the power flow equation of the power grid after loading the DSSC based on the voltage of the node corresponding to the new load, obtain a new power flow solution, and go to 2). If it exceeds, obtain the voltage of the node corresponding to the new load.

[0042] According to the voltage of the nodes in the power grid when the load increases to exceed the allowable value, the power flow equation of the power grid after the DSSC is installed is calculated. Based on the calculation results and the static stability criterion of the power grid, the static stability of the power grid is judged, including:

[0043] When the load increases to exceed the allowable value, the voltage U of the node in the power grid w , perform power flow calculation on the power flow equation of the power grid after loading DSSC;

[0044] If a power flow solution exists, set U w As the voltage collapse point, the power flow solution is taken as the maximum active output of the new energy, and the static stability of the power grid is judged according to the static stability criterion of the power grid.

[0045] A device for determining the static stability of a power grid, comprising:

[0046] The power grid power flow equation module obtains the power flow equation of the power grid after the DSSC is installed based on the structure of the DSSC and the working principle of the DSSC for line power flow control; wherein the power grid is a power grid containing new energy;

[0047] The grid static stability criterion module performs power flow calculation and voltage and active power analysis on the power flow equation of the grid equipped with DSSC without any grid scenario to obtain the static stability criterion of the grid;

[0048] The node voltage module, based on the scenario of increasing the load on a single node in the power grid, performs power flow calculation and voltage and active power analysis on the power flow equation of the power grid equipped with DSSC, and determines the voltage of the node in the power grid when the load increases to exceed the allowable value;

[0049] The stability judgment module performs power flow calculation on the power flow equation of the power grid after the DSSC is loaded according to the voltage of the node in the power grid when the load increases to exceed the allowable value, and judges the static stability of the power grid based on the calculation results and the static stability criterion of the power grid.

[0050] A computer-readable storage medium stores one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, cause the computing device to execute a method for determining static stability of a power grid.

[0051] A computing device includes one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for executing a method for determining static stability of a power grid.

[0052] The beneficial effects achieved by the present invention are as follows: Based on the structure of DSSC and the working principle of DSSC for line flow control, the present invention obtains the flow equation of the power grid after loading DSSC, performs flow calculation and voltage active power analysis on the flow equation in the absence of any power grid scenario, obtains the static stability criterion of the power grid, and performs the static stability judgment of the power grid according to the power grid static stability criterion in the scenario of increasing the load on a single node of the power grid, thereby realizing a static stability judgment method applicable to the power grid containing DSSC. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Flowchart of a method for determining the static stability of a power grid;

[0054] Figure 2 It is the DSSC equivalent injection power model;

[0055] Figure 3 This is a typical schematic diagram of new energy grid connection. DETAILED DESCRIPTION

[0056] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0057] like Figure 1 As shown, a method for determining the static stability of a power grid includes the following steps:

[0058] Step 1: According to the structure of DSSC and the working principle of DSSC for line power flow control, the power flow equation of the power grid after the DSSC is installed is obtained; wherein the power grid is a power grid containing new energy.

[0059] Step 2: In the absence of any power grid scenario, the power flow equation of the power grid equipped with DSSC is used to perform power flow calculation and voltage-active power analysis to obtain the static stability criterion of the power grid.

[0060] Step 3: Based on the scenario of increasing the load on a single node in the power grid, the power flow equation of the power grid after installing the DSSC is used for power flow calculation and voltage-active power analysis to determine the voltage of the node in the power grid when the load increases to exceed the allowable value.

[0061] Step 4: Based on the voltage of the nodes in the power grid when the load increases to exceed the allowable value, the power flow equation of the power grid after loading the DSSC is calculated, and the static stability of the power grid is judged based on the calculation results and the static stability criterion of the power grid.

[0062] In the above method, the power flow equation of the power grid after loading DSSC is obtained according to the structure of DSSC and the working principle of DSSC line power flow control. In the absence of any power grid scenario, the power flow equation is subjected to power flow calculation and voltage and active power analysis to obtain the static stability criterion of the power grid. Based on the scenario of increasing the load on a single node in the power grid, the static stability of the power grid is judged according to the static stability criterion of the power grid, thereby realizing a static stability judgment method suitable for power grids containing DSSC.

[0063] In the above method, first, based on the structure of the DSSC and the working principle of the DSSC for line power flow control, the equivalent injection power of the node in the power grid after the DSSC is installed is obtained.

[0064] Specifically, we can first analyze the structure of DSSC. DSSC uses a single-phase inverter to control the AC side of the power grid to output a variable voltage, thereby changing the impedance of the line in the power grid and adjusting the power flow or node voltage in the power grid.

[0065] Define line ij as the line between the i-th node and the j-th node in the power grid. The active power flowing through the line can be expressed as:

[0066]

[0067] Among them, V i 、V j are the amplitudes of the voltages at both ends of line ij, Δδ=δ i -δ j is the phase angle difference between the two ends of the line, X ij is the reactance of the line ij impedance.

[0068] When the DSSC is connected in series to the target line, it is equivalent to connecting a voltage perpendicular to the current of the target line. At this time, the active power flow of the target line is as follows:

[0069]

[0070] Among them, V DSSC The voltage injected into the target line of the DSSC.

[0071] Formula (2) can be further simplified as follows:

[0072]

[0073] Considering that the voltage at both ends of the line is close to 1.0pu, the phase difference Δδ at both ends of the line is ≈ 0, that is, Therefore, by further simplifying Equation (3), the DC power flow of DSSC can be expressed as:

[0074]

[0075] It can be seen from the above formula that in order to control the power flow of the line, it can be achieved by changing the amplitude and phase of the voltage injected into the grid by the DSSC.

[0076] Furthermore, based on the working principle of DSSC for line power flow control, a mathematical model of DSSC node equivalent power injection can be constructed.

[0077] For any complex power system, the DSSC power injection model of a certain line can be seen Figure 2 ,in is the admittance to ground, b c is the parameter in the earth admittance, is the voltage vector of the ith node, U i is the voltage amplitude of the i-th node, δ i For U i The corresponding phase angle, is the voltage vector of the jth node, U j is the voltage amplitude of the jth node, δ j For U j The corresponding phase angle.

[0078] Assume that the voltage U injected into the grid by DSSC DSSC The phase is δ DSSC , the equivalent injection powers at both ends of the DSSC access line are:

[0079]

[0080]

[0081] P jD =U DSSC U j [gcos(δ D -δ j )-bsin(δD -δ j )]

[0082] Q jD =-U DSSC U j [gsin(δ D -δ j )+bcos(δ D -δ j )]

[0083] Among them, P iD is the active power injected by the i-th node after loading DSSC, P jD = The active power injected by the jth node after loading DSSC, Q iD = The reactive power injected by the ith node after DSSC is loaded, Q jD is the reactive power injected by the jth node after DSSC is installed, U DSSC is the DSSC injection voltage, δ D For U DSSC Phase, U i is the voltage of the ith node, U j is the voltage of the jth node, δ i is the phase angle of the i-th node, δ j is the phase angle of the jth node, parameter parameter R+jX is the impedance of line ij, R is the resistance part of R+jX, and X is the reactance part of R+jX.

[0084] According to the equivalent injected power of the grid nodes after DSSC is installed and the grid power flow calculation equation, the grid power flow equation after DSSC is installed can be obtained.

[0085] The transmission power of a line equipped with DSSC can be expressed as:

[0086]

[0087]

[0088] Among them, P ij , Q ij are the active and reactive power of the line respectively.

[0089] For a power grid with n nodes, after the ith node of line ij is loaded with DSSC, the power flow equation of the power grid can be expressed as:

[0090]

[0091]

[0092]

[0093]

[0094] Where ΔP i is the active power injected into the i-th node, ΔQ i is the reactive power injected into the i-th node, ΔP j is the active power injected into the jth node, ΔQ j is the reactive power injected by the jth node, G ij is the real part of the admittance of line ij, B ij is the imaginary part of the admittance of line ij, δ i is the phase angle of the i-th node, δ j is the phase angle of the jth node, U i is the voltage of the ith node, U j is the voltage of the jth node, n is the number of nodes in the grid, P iD is the active power injected by the i-th node after loading DSSC, P jD = The active power injected by the jth node after loading DSSC, Q iD = The reactive power injected by the ith node after DSSC is loaded, Q jD is the reactive power injected by the jth node after DSSC is loaded, P i is the active power of the i-th node, Q i is the reactive power of the ith node, P j is the active power of the jth node, Q j is the reactive power of the jth node.

[0095] In the absence of any power grid scenario, a power flow calculation (i.e., a theoretical calculation) is performed on the power flow equation of the power grid after the DSSC is installed to obtain a static voltage stability index; wherein the static voltage stability index is an indicator of the existence of a solution to the power flow equation of the power grid.

[0096] Figure 3 This is a typical schematic diagram of renewable energy grid connection. In the figure, P0 and Q0 represent the active and reactive power output of renewable energy. D , Q D represents the active power compensation and reactive power compensation generated by the series DSSC, P′ is the active power output by the renewable energy grid-connected to the grid, Q′ is the reactive power output by the renewable energy grid-connected to the grid, R′+jX′ is the impedance between the renewable energy grid-connected point and the balance node, R′ is the resistance part of R′+jX′, X′ is the reactance part of R′+jX′, E∠α represents the voltage vector at the balance point, E is the voltage amplitude at the balance point, α is the phase angle of the voltage at the balance point, U∠θ represents the voltage vector at the renewable energy grid-connected point, U is the voltage amplitude at the renewable energy grid-connected point, and θ is the phase angle of the voltage at the renewable energy grid-connected point.

[0097] Calculate the power flow of the power grid:

[0098]

[0099] in, for The conjugation of .

[0100] make Multiply the left and right sides of equation (5) by , and separating the real and imaginary parts of the result, we get:

[0101]

[0102] U y E x -U x E y =P′X′-Q′R′ (7)

[0103] Among them, E x 、E y They are Decomposed into vectors in the x-axis and y-axis directions, U x 、U y They are Decompose into vectors in the x-axis and y-axis directions.

[0104] From formula (7), we can get:

[0105] Will U x 、U y Substituting into formula (6), we can get:

[0106]

[0107]

[0108] Equations (8) and (9) can be viewed as equations about U x 、U y For a quadratic equation of one variable, if the tidal current solution is to exist, then the solution of the equation must exist. Therefore, the discriminant of the existence of the equation for these two equations is obtained:

[0109]

[0110]

[0111] Combine equations (10) and (11) and let We can get:

[0112] E 4 -4E 2(P′X′+Q′R′)-4(P′X′-Q′R′) 2 ≥0 (12)

[0113] Define the static voltage stability index S = E 4 -4E 2 (P′X′+Q′R′)-4(P′X′-Q′R′) 2 , when S≥0, it means that there is a power flow solution for the power grid power flow equation calculation.

[0114] However, it is obvious that equation (12) can be derived from equations (10) and (11), but the reverse derivation is not true. Therefore, using only the static voltage stability index cannot accurately characterize the static stability of the system. It is necessary to further perform voltage active power analysis (i.e., theoretical analysis) on the grid flow equation after loading DSSC without any grid scenario to obtain the margin index of voltage active power sensitivity; among which, the margin index of voltage active power sensitivity is the distance from the current active power output to the voltage collapse point.

[0115] like Figure 3 , according to the power grid flow calculation, we can get:

[0116] (P′+jQ′)(R′-jX′)=(Ucosθ-jUsinθ-E)(Ucosθ+jUsinθ) (13)

[0117] By equating the real part and the imaginary part in formula (13), we can obtain:

[0118] P′R′ 2 +P′X′ 2 =U 2 R′+(X′sinθ-R′cosθ)UE (14)

[0119] Q′R′ 2 +Q′X′ 2 =U 2 X′-(X′sinθ+R′cosθ)UE (15)

[0120] Combining equations (14) and (15) we can get:

[0121]

[0122]

[0123] Substitute sinθ and cosθ into equations (14) and (15) respectively and simplify to obtain:

[0124] U 4 -(E 2 +2P′R′+2Q′X′)U 2 +(P′2 +X′ 2 )(P′ 2 +Q′ 2 )=0 (16)

[0125] Formula (16) can be regarded as the equation about U 2 The solution of the quadratic equation can be obtained as:

[0126]

[0127] Analyzing the relationship between U and P' in equation (17), we can see that as P' increases, the grid voltage U gradually decreases. When the voltage collapse point is reached, P' reaches a maximum value, and at this time, the rate of change of U relative to P' also reaches the maximum. Therefore, we can take the partial derivative of P' on both sides of equation (17) and set Denotes the partial derivative of U with respect to P′, then let Substituting it into formula (17), we can find the maximum value of P′ Max ,Right now:

[0128]

[0129] Assume that the current active power output of renewable energy is P Now , then define the margin index of voltage active sensitivity From the above analysis, we can see that the physical meaning of K is the distance from the current active output to the voltage collapse point. When K > 0, the system static voltage is stable; otherwise, the system static voltage is unstable.

[0130] Therefore, based on the static voltage stability index and the margin index of voltage active power sensitivity, the static stability criterion of the power grid is obtained as follows: S ≥ 0 and K < 0; among them, S ≥ 0 indicates that there is a power flow solution in the power flow equation calculation, and K < 0 indicates that the current active power output of the power grid is not at the voltage collapse point.

[0131] Based on the scenario of increasing the load at a single node in the power grid, the power flow equation of the power grid equipped with DSSC is used for power flow calculation and voltage and active power analysis to determine the voltage at the node in the power grid when the load increases to exceed the allowable value, including:

[0132] 1) Under preset initial conditions, the power flow equation of the power grid after the DSSC is installed is calculated to obtain the power flow solution;

[0133] 2) Taking the power flow solution as the initial point, calculate the partial derivative of the voltage with respect to the active power at the initial point, and determine the direction of active voltage change based on the partial derivative;

[0134] 3) Select any node in the power grid as the target node, and increase the load of the target node by a preset step size along the direction of active voltage change to obtain a new load;

[0135] 4) Determine whether the new load exceeds the allowable value. If not, perform power flow calculation on the power flow equation of the power grid after loading the DSSC based on the voltage of the node corresponding to the new load, obtain a new power flow solution, and go to 2). If it exceeds, obtain the voltage of the node corresponding to the new load.

[0136] When the load increases to exceed the allowable value, the voltage U of the node in the power grid w , calculate the power flow equation of the power grid after DSSC is installed. If there is a power flow solution, replace U w As the voltage collapse point, the power flow solution is the maximum active output of the new energy, and according to the static stability criterion of the power grid, the static stability of the power grid is judged.

[0137] The continuous power flow method of the present invention, combined with the indicators S and K, can not only analyze the static stability of a single-node load increase scenario in a renewable energy grid-connected system, but can also be used to analyze the static stability under various conditions such as multi-node or even random node load increase. It can accurately evaluate the static voltage stability state under various conditions during the renewable energy grid-connected process, and therefore can guide the location and capacity of DSSC installation, thereby promoting the grid connection and consumption of large-scale renewable energy.

[0138] The present invention has the advantages of easy implementation, accurate analysis, and wide adaptability. It can use Flexible AC Transmission Systems (FACTS) technology from the grid side to solve the static voltage stability problem in the grid connection of new energy sources, ensuring the safe and stable operation of the new energy grid.

[0139] Based on the same technical solution, the present invention also discloses a software device for the above method, a device for determining the static stability of a power grid, comprising:

[0140] The power grid flow equation module obtains the power flow equation of the power grid after the DSSC is installed according to the structure of the DSSC and the working principle of the DSSC for line flow control; wherein the power grid is a power grid containing new energy.

[0141] The grid static stability criterion module performs power flow calculation and voltage and active power analysis on the power flow equation of the grid equipped with DSSC without any grid scenario to obtain the static stability criterion of the grid.

[0142] The node voltage module, based on the scenario of increasing the load on a single node in the power grid, performs power flow calculation and voltage active power analysis on the power flow equation of the power grid equipped with DSSC, and determines the voltage of the node in the power grid when the load increases to exceed the allowable value.

[0143] The stability judgment module performs power flow calculation on the power flow equation of the power grid after the DSSC is loaded according to the voltage of the node in the power grid when the load increases to exceed the allowable value, and judges the static stability of the power grid based on the calculation results and the static stability criterion of the power grid.

[0144] The data processing flow of each of the above modules is consistent with the corresponding steps of the method and will not be repeated here.

[0145] Based on the same technical solution, the present invention also discloses a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to execute a method for determining the static stability of a power grid.

[0146] Based on the same technical solution, the present invention also discloses a computing device, including one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing a method for determining the static stability of a power grid.

[0147] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0148] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes 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 processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0149] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0150] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0151] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A method for determining the static stability of a power grid, characterized in that: include: According to the structure of the DSSC and the working principle of the DSSC for line power flow control, the equivalent injected power of the nodes in the power grid after the DSSC is installed is obtained. According to the equivalent injected power of the nodes in the power grid after the DSSC is installed and the power grid power flow calculation equation, the power grid power flow equation after the DSSC is installed is obtained; wherein the power grid is a power grid containing new energy; In the absence of any power grid scenario, the power flow equation of the power grid equipped with DSSC is used to calculate the power flow and analyze the voltage and active power to obtain the static stability criterion of the power grid; Based on the scenario of increasing the load at a single node in the power grid, the power flow equation of the power grid equipped with DSSC is used for power flow calculation and voltage and active power analysis to determine the voltage at the node in the power grid when the load increases to exceed the allowable value; According to the voltage of the nodes in the power grid when the load increases to exceed the allowable value, the power flow equation of the power grid after the DSSC is installed is calculated, and the static stability of the power grid is judged based on the calculation results and the static stability criterion of the power grid; The ith node of line ij in the power grid is loaded with a DSSC. The equivalent injected power of the node in the power grid after loading the DSSC is: P jD =U DSSC U j [gcos(δ D -d j )-bsin(δ D -d j )] Q jD =-U DSSC U j [gsin(δ D -d j )+bcos(δ D -d j )] Among them, line ij is the line between the i-th node and the j-th node in the power grid, P iD , Q iD are the equivalent injected active power and the equivalent injected reactive power of the i-th node after DSSC is installed, P jD , Q jD are the equivalent injected active power and reactive power of the jth node after DSSC is installed, U DSSC is the DSSC injection voltage, δ D For U DSSC Phase, U i , δ i are the voltage and phase angle of the i-th node, U j , δ j are the voltage and phase angle of the j-th node respectively; parameter parameter R is the resistance part of the line ij impedance, X is the reactance part of the line ij impedance, b c is the parameter in the earth admittance.

2. A method for determining the static stability of a power grid according to claim 1, characterized in that: In the power grid, the ith node of line ij is loaded with a DSSC. The power flow equation of the power grid after loading the DSSC is: Where ΔP i , ΔQ i are respectively the active and reactive power injected into the i-th node, ΔP j , ΔQ j are the active and reactive power injected into the jth node, G ij 、B ij are the real and imaginary parts of the admittance of line ij, n is the number of nodes in the power grid, P i , Q i are respectively the active and reactive power of the i-th node, P j , Q j are the active and reactive power of the j-th node respectively.

3. The method for determining the static stability of a power grid according to claim 1, wherein: Without any power grid scenario, the power flow equation of the power grid equipped with DSSC is used for power flow calculation and voltage and active power analysis to obtain the static stability criteria of the power grid, including: In the absence of any power grid scenario, the power flow equation of the power grid equipped with DSSC is calculated to obtain the static voltage stability index of the power grid. The static voltage stability index is an indicator of the existence of a solution to the power flow equation. In the absence of any power grid, the power flow equation of the power grid equipped with DSSC is analyzed for voltage and active power to obtain the margin index of the power grid's voltage and active power sensitivity. The margin index of the voltage and active power sensitivity is the distance from the current active power output of the power grid to the voltage collapse point in the power grid. According to the static voltage stability index and the margin index of voltage active sensitivity, the static stability criterion of the power grid is obtained.

4. A method for determining the static stability of a power grid according to claim 3, characterized in that: The static voltage stability index is: S=E 4 -4E 2 (P′X′+Q′R′)-4(P′X′-Q′R′) 2 The margin index of voltage active sensitivity is: Among them, S is the static voltage stability index, P' and Q' are respectively the active power and reactive power output to the grid after the new energy is connected to the grid, R' is the resistance part of the impedance between the new energy grid connection point and the balance node, X' is the reactance part of the impedance between the new energy grid connection point and the balance node, E is the voltage amplitude of the balance point, K is the margin index of the voltage active sensitivity, P Now is the current active power output of new energy, P Max Make the greatest contribution to new energy.

5. A method for determining the static stability of a power grid according to claim 4, characterized in that: The static stability criterion of the power grid is: S ≥ 0 and K < 0; among them, S ≥ 0 means that the calculation result of the power flow equation has a power flow solution, and K < 0 means that the current active power output of the power grid is not at the voltage collapse point.

6. A method for determining the static stability of a power grid according to claim 1, characterized in that: Based on the scenario of increasing the load at a single node in the power grid, the power flow equation of the power grid equipped with DSSC is used for power flow calculation and voltage and active power analysis to determine the voltage at the node in the power grid when the load increases to exceed the allowable value, including: 1) Under preset initial conditions, the power flow equation of the power grid after the DSSC is installed is calculated to obtain the power flow solution; 2) Taking the power flow solution as the initial point, calculate the partial derivative of the voltage with respect to the active power at the initial point, and determine the direction of active voltage change based on the partial derivative; 3) Select any node in the power grid as the target node, and increase the load of the target node by a preset step size along the direction of active voltage change to obtain a new load; 4) Determine whether the new load exceeds the allowable value. If not, perform power flow calculation on the power flow equation of the power grid after loading the DSSC based on the voltage of the node corresponding to the new load, obtain a new power flow solution, and go to 2). If it exceeds, obtain the voltage of the node corresponding to the new load.

7. A method for determining the static stability of a power grid according to claim 1, characterized in that: According to the voltage of the nodes in the power grid when the load increases to exceed the allowable value, the power flow equation of the power grid after the DSSC is installed is calculated. Based on the calculation results and the static stability criterion of the power grid, the static stability of the power grid is judged, including: When the load increases to exceed the allowable value, the voltage U of the node in the power grid w , perform power flow calculation on the power flow equation of the power grid after loading DSSC; If a power flow solution exists, set U w As the voltage collapse point, the power flow solution is taken as the maximum active output of the new energy, and the static stability of the power grid is judged according to the static stability criterion of the power grid.

8. A device for determining the static stability of a power grid, characterized in that: include: The power grid flow equation module obtains the equivalent injected power of the nodes in the power grid after the DSSC is installed based on the structure of the DSSC and the working principle of the DSSC for line flow control. Based on the equivalent injected power of the nodes in the power grid after the DSSC is installed and the power grid flow calculation equation, the power grid after the DSSC is installed is obtained; wherein the power grid is a power grid containing new energy; The grid static stability criterion module performs power flow calculation and voltage and active power analysis on the power flow equation of the grid equipped with DSSC without any grid scenario to obtain the static stability criterion of the grid; The node voltage module, based on the scenario of increasing the load on a single node in the power grid, performs power flow calculation and voltage and active power analysis on the power flow equation of the power grid equipped with DSSC, and determines the voltage of the node in the power grid when the load increases to exceed the allowable value; The stability judgment module calculates the power flow equation of the power grid after the DSSC is installed based on the voltage of the nodes in the power grid when the load increases to exceed the allowable value, and judges the static stability of the power grid based on the calculation results and the static stability criterion of the power grid; The ith node of line ij in the power grid is loaded with a DSSC. The equivalent injected power of the node in the power grid after loading the DSSC is: P jD =U DSSC U j [gcos(δ D -d j )-bsin(δ D -d j )] Q jD =-U DSSC U j [gsin(δ D -d j )+bcos(δ D -d j )] Among them, line ij is the line between the i-th node and the j-th node in the power grid, P iD , Q iD are the equivalent injected active power and the equivalent injected reactive power of the i-th node after DSSC is installed, P jD , Q jD are the equivalent injected active power and reactive power of the jth node after DSSC is installed, U DSSC is the DSSC injection voltage, δ D For U DSSC Phase, U i , δ i are the voltage and phase angle of the i-th node, U j , δ j are the voltage and phase angle of the j-th node respectively; parameter parameter R is the resistance part of the line ij impedance, X is the reactance part of the line ij impedance, b c is the parameter in the earth admittance.

9. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions that, when executed by a computing device, cause the computing device to perform any one of the methods according to claims 1 to 7.

10. A computing device, characterized in that include: One or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs comprising instructions for performing any of the methods according to claims 1 to 7.

Images