Numerical Oscillation Suppression Method for Electromechanical Transient Simulation of SVG

Abstract

This invention discloses a numerical oscillation suppression method applicable to SVG (Static Var Generator) electromechanical transient simulation, which addresses the numerical oscillation problem caused by the introduction of SVG during electromechanical transient simulation. First, considering the system state variables, system algebraic variables, and node injection currents of the power system during transient simulation, an electromechanical transient simulation model of the power system is constructed. Next, the electromechanical transient simulation model is differentially processed to obtain the iterative equations at time n+1. Finally, the iterative equations at time n+1 are solved iteratively using alternating methods combined with linear interpolation to obtain the transient simulation solution of the power system. Thus, in the original alternating solution of the differential-algebraic equation system, alternating solutions combined with linear interpolation are further introduced, ensuring that the implicit trapezoidal integral structure in the fast dynamic process of SVG is not destroyed during the solution process, effectively suppressing the numerical oscillation problem in electromechanical transient simulation of the power system caused by the introduction of SVG.

Description

Technical Field

[0001] This invention relates to the field of power simulation technology, and in particular to a numerical oscillation suppression method for electromechanical transient simulation of SVG, a numerical oscillation suppression device for electromechanical transient simulation of SVG, an electronic device, and a storage medium. Background Technology

[0002] With the large-scale integration of new energy sources and power electronic devices into the power grid, the complexity of electromechanical transient simulation of power systems has increased dramatically. SVG (Static Var Generator) is an advanced power electronic device widely used in modern power systems to improve power quality and enhance transmission system stability. Through rapid response and precise control of reactive power output, SVG can provide or absorb large amounts of reactive current within milliseconds, effectively regulating grid voltage, suppressing harmonics, and compensating for unbalanced loads.

[0003] Existing electromechanical transient simulation tools commonly use alternating solution algorithms based on implicit trapezoidal integrals. However, in electromechanical transient simulations, power electronic devices, represented by SVG, exhibit significantly different time constants in their fast dynamic control processes compared to the slow dynamic control processes of traditional synchronous machines (the fast dynamic time constant of SVG is much smaller than that of synchronous generator systems). This increased rigidity in the electromechanical transient simulation process makes it highly susceptible to numerical oscillations in scenarios with a high proportion of power electronic devices. Therefore, it is urgent to improve existing electromechanical SVG transient simulation algorithms to suppress the numerical oscillations introduced by SVG during simulation. Summary of the Invention

[0004] This invention provides a numerical oscillation suppression method, a numerical oscillation suppression device, an electronic device, and a storage medium for electromechanical transient simulation of SVG, which are used to solve or partially solve the numerical oscillation problem caused by the introduction of SVG during electromechanical transient simulation.

[0005] This invention provides a numerical oscillation suppression method suitable for electromechanical transient simulation of SVG, comprising:

[0006] Simultaneously considering the system state variables, system algebra variables, and node injection currents of the power system during the transient simulation process, an electromechanical transient simulation model of the power system is constructed.

[0007] The electromechanical transient simulation model is differentially processed to obtain the iterative equation at time n+1;

[0008] The transient simulation results of the power system are obtained by iteratively solving the iterative equation at time n+1 using alternating linear interpolation.

[0009] Optionally, the step of simultaneously considering the system state variables, system algebraic variables, and node injection currents of the power system during the transient simulation process to construct the electromechanical transient simulation model of the power system includes:

[0010] Simultaneously considering the system state variables, system algebraic variables, and node injection currents of the power system during the transient simulation process, the first transient simulation equation set of the SVG is constructed in the form of differential-algebraic equations, and the second transient simulation equation set of the power equipment other than the SVG in the power system is also constructed.

[0011] Obtain the node admittance matrix of the power system, and construct the node voltage equations of the power system based on the node admittance matrix;

[0012] The first transient simulation equation set, the second transient simulation equation set, and the node voltage equations are integrated into the electromechanical transient simulation model of the power system.

[0013] Optionally, the step of performing differential processing on the electromechanical transient simulation model to obtain the iterative equation at time n+1 includes:

[0014] A pre-set first simulation step size is obtained. Based on the first simulation step size, the implicit trapezoidal integral method is used to perform difference processing on the first transient simulation equation set and the second transient simulation equation set respectively, to obtain the first difference equation set corresponding to the first transient simulation equation set and the second difference equation set corresponding to the second transient simulation equation set.

[0015] Construct the node voltage equation at time n+1;

[0016] The first set of difference equations, the second set of difference equations, and the node voltage equation at time n+1 are integrated into an iterative equation at time n+1.

[0017] Optionally, for the k-th iteration at time n+1, the alternating iterative solution process combining linear interpolation includes:

[0018] Step S01: When k=0, initialize the initial values ​​of the system algebraic variable vector in the node voltage equation at time n+1;

[0019] Step S02: When k≠0, combine linear interpolation and consider the simulation step size difference, solve the first system state variable vector and the first node injection current vector at time n+1 through the first difference equation system, and solve the second system state variable vector and the second node injection current vector at time n+1 through the second difference equation system.

[0020] Step S03: Substitute the first system state variable vector and the first node injected current vector into the node voltage equation at time n+1 to solve for the first system algebraic variable vector at time n+1; substitute the second system state variable vector and the second node injected current vector into the node voltage equation at time n+1 to solve for the second system algebraic variable vector at time n+1.

[0021] Step S04: Determine whether the algebraic variable vector of the first system and the algebraic variable vector of the second system meet the preset error conditions, and execute the subsequent iterative solution process based on the error judgment result.

[0022] Optionally, the step of combining linear interpolation, while considering simulation step size differences, to solve for the first system state variable vector and the first node injected current vector at time n+1 using the first difference equation system, and to solve for the second system state variable vector and the second node injected current vector at time n+1 using the second difference equation system, includes:

[0023] The second simulation step size is determined based on the first simulation step size. The second simulation step size is smaller than the first simulation step size, and the first simulation step size and the second simulation step size are in a positive integer proportional relationship.

[0024] For the SVG, the first system state variable vector and the first node injection current vector at time n+1 are solved by the first difference equation system, and in the solution process, linear interpolation is combined with the second simulation step size for calculation.

[0025] For the power equipment in the power system other than the SVG, the first simulation step size is used, and the second system state variable vector and the second node injection current vector at time n+1 are solved by the second difference equation system.

[0026] Optionally, the step of using the second simulation step size in conjunction with linear interpolation during the solution process includes:

[0027] Obtain the system algebraic variable vector at time n and the system algebraic variable vector at time n+1 of the SVG;

[0028] Using linear interpolation, based on the system algebraic variable vector at time n, the system algebraic variable vector at time n+1, and the positive integer ratio between the second simulation step size and the first simulation step size, the intermediate value of the system algebraic variable vector of the SVG at each of the second simulation step sizes in the k-th iteration at time n+1 is calculated one by one.

[0029] Optionally, the step of determining whether the first system algebraic variable vector and the second system algebraic variable vector meet the preset error conditions, and executing subsequent iterative solution processes based on the error determination results, includes:

[0030] Determine whether the algebraic variable vectors of the first system and the algebraic variable vectors of the second system both meet the preset error requirements;

[0031] If so, let k=0, and continue the alternating iterative solution process at time n+2 according to steps S01 to S04;

[0032] If not, then continue with steps S02 to S04 to execute the (k+1)th alternating iteration solution process at time n+1.

[0033] The present invention also provides a numerical oscillation suppression device suitable for electromechanical transient simulation of SVG, comprising:

[0034] The model building unit is used to simultaneously consider the system state variables, system algebraic variables, and node injection currents of the power system during the transient simulation process, and to build the electromechanical transient simulation model of the power system.

[0035] The differential processing unit is used to perform differential processing on the electromechanical transient simulation model to obtain the iterative equation at time n+1.

[0036] The alternating iterative solution unit is used to perform alternating iterative solution of the iterative equation at time n+1, combined with linear interpolation, to obtain the transient simulation solution result of the power system.

[0037] The present invention also provides an electronic device, the device comprising a processor and a memory:

[0038] The memory is used to store program code and transmit the program code to the processor;

[0039] The processor is configured to execute, according to instructions in the program code, a numerical oscillation suppression method for electromechanical transient simulation of SVG as described in any of the preceding embodiments.

[0040] The present invention also provides a computer-readable storage medium for storing program code for performing a numerical oscillation suppression method for electromechanical transient simulation of SVG as described in any of the preceding claims.

[0041] As can be seen from the above technical solutions, the present invention has the following advantages:

[0042] A numerical oscillation suppression method suitable for SVG-based electromechanical transient simulation is presented. First, the system state variables, system algebraic variables, and node injection currents of the power system are simultaneously considered during the transient simulation process to construct an electromechanical transient simulation model of the power system. Next, the electromechanical transient simulation model is differentially processed to obtain the iterative equations at time n+1. Finally, the iterative equations at time n+1 are solved iteratively using alternating methods combined with linear interpolation to obtain the transient simulation solution of the power system. Thus, in the original alternating solution process of the differential-algebraic equation system, alternating solutions combined with linear interpolation are further introduced, ensuring that the implicit trapezoidal integral structure in the fast dynamic process of SVG is not destroyed during the solution process, effectively suppressing the numerical oscillation problem in the electromechanical transient simulation of the power system caused by the introduction of SVG. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A flowchart illustrating the steps of a numerical oscillation suppression method suitable for electromechanical transient simulation of SVG;

[0045] Figure 2 This is a block diagram of the transfer function of an SVG with constant voltage control.

[0046] Figure 3 This is a schematic diagram of the overall process for a numerical oscillation suppression method suitable for electromechanical transient simulation of SVG;

[0047] Figure 4 This is a structural block diagram of a numerical oscillation suppression device suitable for electromechanical transient simulation of SVG. Detailed Implementation

[0048] The present invention provides a numerical oscillation suppression method, a numerical oscillation suppression device, an electronic device, and a storage medium for electromechanical transient simulation of SVG, which are used to solve or partially solve the numerical oscillation problem caused by the introduction of SVG in the electromechanical transient simulation process.

[0049] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0050] As an example, the commonly used solution algorithm in existing electromechanical transient simulation tools is an alternating solution algorithm based on implicit trapezoidal integrals. However, in the electromechanical transient simulation process, power electronic devices, represented by SVG, have significantly different time constants for their fast dynamic processes compared to the slow dynamic processes of traditional synchronous machines (the time constant of the fast dynamic process of SVG is much smaller than that of the slow dynamic process of synchronous generator systems). This increased rigidity of the electromechanical transient simulation process makes it prone to numerical oscillations in scenarios with a high proportion of power electronic devices. Therefore, it is urgent to improve the existing electromechanical SVG transient simulation algorithm to suppress the numerical oscillations introduced by SVG during the simulation process.

[0051] Therefore, one of the core inventive points of this invention is: addressing the shortcomings of current technology, it proposes an alternating fast-slow dynamic process solution method that considers the fast dynamic process iteration of SVG during the slow dynamic process iteration. First, it simultaneously considers the system state variables, system algebraic variables, and node injection currents during the transient simulation of the power system to construct an electromechanical transient simulation model of the power system. Then, it performs differential processing on the electromechanical transient simulation model based on the implicit trapezoidal integral method to obtain the iterative equation at time n+1. Finally, it performs alternating iterative solutions combining linear interpolation on the iterative equation at time n+1 to obtain the transient simulation solution result of the power system. Thus, in the original alternating solution process of the differential-algebraic equation system, the alternating solution of the fast-slow dynamic process is further introduced, combined with linear interpolation, forming an alternating iterative solution process that simultaneously considers both the system-algebraic level and the SVG (fast)-other power equipment (slow) level. This ensures that the structure of the implicit trapezoidal integral in the SVG fast dynamic process is not destroyed during the solution process, effectively suppressing the numerical oscillation problem in the electromechanical transient simulation of the power system caused by the introduction of SVG.

[0052] In this embodiment of the invention, the power system requiring transient simulation is connected to an SVG with fast dynamic process characteristics. (Refer to...) Figure 1 The diagram illustrates a flowchart of a numerical oscillation suppression method for electromechanical transient simulation of SVG provided by an embodiment of the present invention, which specifically includes the following steps:

[0053] Step 101: Simultaneously consider the system state variables, system algebraic variables, and node injection currents of the power system during the transient simulation process, and construct the electromechanical transient simulation model of the power system.

[0054] This step mainly involves constructing an electromechanical transient simulation model of a power system containing SVG.

[0055] In some embodiments, the process of constructing an electromechanical transient simulation model of a power system, considering the system state variables, system algebraic variables, and nodal injection currents during the transient simulation process, includes the following sub-steps 1011 to 1013:

[0056] Step 1011: Simultaneously consider the system state variables, system algebraic variables, and node injection currents of the power system during the transient simulation process. Construct the first transient simulation equation set of SVG in the form of differential-algebraic equations, and simultaneously construct the second transient simulation equation set of power equipment other than SVG in the power system.

[0057] The mathematical model of a power system can be described as a set of differential-algebraic equations. In a power system containing SVG, the electromechanical transient simulation model of the system can be described as the following two sets of differential-algebraic equations:

[0058] (1)

[0059] (2)

[0060] To distinguish the SVG from other power equipment in the power system, the differential-algebraic equation set represented by equation (1) is taken as the first transient simulation equation set of the SVG, and the differential-algebraic equation set represented by equation (2) is taken as the second transient simulation equation set of power equipment other than the SVG in the power system.

[0061] In equations (1) and (2), This is a vector of system state variables; The system is a vector of algebraic variables; Inject current vectors into nodes; The time constant vector of the dynamic process; A system of differential equations representing the dynamic process of the system; The system consists of a set of algebraic equations; subscript Indicates that state variables and algebraic variables belong to SVG; subscript This indicates that state variables and algebraic variables belong to the power equipment part of the power system other than SVG. The "·" above indicates Regarding time Find the derivative.

[0062] Taking a constant voltage controlled SVG in a DSP as an example, the differential-algebraic equations of the model can be expressed as follows: Figure 2 The transfer function block diagram is shown below.

[0063] The input for constant voltage control is the SVG constant voltage control node voltage. Constant voltage control reference voltage Auxiliary input signal Grid connection point voltage The output is the reactive current injected into the system by the SVG. ; To measure the time constant of the process; , The time constant of the first-level lead-lag element; , This is the time constant for the second-level lead-lag element; The time constant of the proportional element; This is the time constant of the SVG response delay stage; , These are the magnification factors for the proportional and integral components, respectively. The slope of the VI property of the SVG; , , , , , Limit the voltage and current at each stage; This is the equivalent reactance between the SVG and the grid connection point.

[0064] Step 1012: Obtain the node admittance matrix of the power system, and construct the node voltage equations of the power system based on the node admittance matrix;

[0065] In equations (1) and (2) , Simultaneously satisfying the network equations (node ​​voltage equations) shown in equation (3):

[0066] (3)

[0067] in, Let be the nodal admittance matrix of the system.

[0068] Step 1013: Integrate the first transient simulation equation set, the second transient simulation equation set, and the node voltage equations into an electromechanical transient simulation model of the power system.

[0069] Step 102: Perform differential processing on the electromechanical transient simulation model to obtain the iterative equation at time n+1;

[0070] This step mainly involves differentiating the equations constructed above to construct the iterative equation at time n+1.

[0071] In some embodiments, the process of performing differential processing on the electromechanical transient simulation model to obtain the iterative equation at time n+1 includes the following sub-steps 1021 to 1023:

[0072] Step 1021: Obtain the preset first simulation step size. Based on the first simulation step size, use the implicit trapezoidal integral method to perform difference processing on the first transient simulation equation set and the second transient simulation equation set respectively, to obtain the first difference equation set corresponding to the first transient simulation equation set and the second difference equation set corresponding to the second transient simulation equation set.

[0073] To distinguish it from the smaller step sizes used in subsequent steps, the pre-defined system simulation step size is defined as the first simulation step size. Assume the first simulation step size is... By applying the implicit trapezoidal integral method to the difference equations of equations (1) and (2), we can obtain the first difference equation set corresponding to the SVG as shown in equation (4), and the second difference equation set for the remaining part of the system as shown in equation (5):

[0074] (4)

[0075] (5)

[0076] Step 1022: Construct the node voltage equations at time n+1;

[0077] Based on the node voltage equation of equation (5), the network equation of the system at time n+1 (i.e., the node voltage equation at time n+1) is shown in equation (6) below:

[0078] (6)

[0079] Step 1023: Integrate the first set of difference equations, the second set of difference equations, and the node voltage equation at time n+1 into an iterative equation at time n+1.

[0080] Step 103: Solve the iterative equation at time n+1 by combining linear interpolation with alternating iterative methods to obtain the transient simulation solution of the power system.

[0081] This step primarily involves alternately iteratively solving the iterative equations at time n+1 to obtain the final transient simulation results. Specifically, the alternate iterative solution at time n+1 can be divided into two levels. The first level involves alternately solving the system's difference equations and algebraic equations. The second level involves dynamically alternating the solution of the remaining system components and the SVG (Static Variational Characteristic) component.

[0082] In some embodiments, for the k-th iteration at time n+1, the alternating iterative solution process combining linear interpolation can be achieved by executing the following sub-steps S01 to S04:

[0083] Step S01: When k=0, initialize the initial values ​​of the system algebraic variable vector in the node voltage equation at time n+1;

[0084] When k=0, given time n+1 The initial value of the iteration, The superscript 0 represents the iteration number. When k ≠ 0, proceed directly to step S02.

[0085] Step S02: When k≠0, combine linear interpolation and consider the simulation step size difference, solve the first system state variable vector and the first node injection current vector at time n+1 through the first difference equation system, and solve the second system state variable vector and the second node injection current vector at time n+1 through the second difference equation system.

[0086] Step S02 mainly solves for the first system state variable vector at time n+1 using equations (4) and (5). First node injected current vector and the second system state variable vector The second node injected current vector .

[0087] Furthermore, step S02 can be decomposed into the following sub-steps S021 to S023:

[0088] Step S021: Determine the second simulation step size based on the first simulation step size. The second simulation step size is smaller than the first simulation step size, and the first simulation step size and the second simulation step size are in a positive integer proportional relationship.

[0089] Due to the time constant of the fast dynamic process of SVG in equation (4) Much smaller than the time constant of dynamic components of other power equipment in the system. Therefore, in the specific solution, a small step size should be used for the fast dynamic process of SVG. The calculation is performed using the second simulation step size, while a larger step size is used for the slow dynamic processes of other components in the system. Calculate using (first simulation step size). Simultaneously, set the larger step size... and small step length Maintain positive integer ratio That's all.

[0090] Step S022: For SVG, solve the first system state variable vector and the first node injection current vector at time n+1 through the first difference equation system, and in the solution process, combine linear interpolation and use the second simulation step size for calculation;

[0091] For the fast dynamic process of SVG, when using a small step size When performing the simulation, the corresponding equation (4) needs to be rewritten as equation (7):

[0092] (7)

[0093] In equation (7), the subscript satisfy .

[0094] Therefore, in the embodiments of the present invention, the setting of large and small step sizes is equivalent to setting a large time step. Average score a small step In subsequent steps During the iteration process of the value, regardless of What value to take? All meet For example, assume a large step size. Second, In calculating the dynamic process from 0 to 1 second, the slow dynamic process corresponding to other electrical equipment in the system (i.e., the subscript) is considered. (corresponding related equations), using The calculation is performed in seconds, requiring only one integration step to obtain the variable value at 1 second. However, for the fast dynamic process of SVG (i.e., subscript...),... (corresponding related equations), because The seconds need to be calculated step by step: 0.1, 0.2, 0.3...0.9 until 1.0. Therefore, the fast dynamic process involves a total of 10 calculations of equation (7), corresponding to... Take 1, 2, 3, ... 10.

[0095] According to equation (7), the fast dynamic process of SVG is continuously calculated. After each time step, the obtained value is the value of the SVG-related variables at time n+1 during the k-th iteration. , Then, equation (6) can be used to calculate the node voltage equation of the whole system at time n+1.

[0096] In practice, equation (7) is used for continuous calculation. During the fast dynamic process of an SVG at each time step, the algebraic variables in the formula... , It is unknown. Following step S01 above, the fast dynamic process of the SVG can be calculated. The value (equivalent to the fast dynamic process of SVG at time n+1, k times, not yet in time step) The initial value at the start of iterative calculation can be obtained using a linear interpolation method, combined with... as well as The values ​​of intermediate time steps in all fast dynamic processes were obtained through calculation. ,Right now:

[0097] (8)

[0098] The time step of each fast dynamic process can be calculated by interpolation using equation (8). of This ensures that the implicit trapezoidal integral structure of equation (7) is not destroyed. While using a large time step in the slow dynamic process, the large time step is divided into multiple small time steps on average and set as the iterative time step of the fast dynamic process. Furthermore, linear interpolation is combined to perform alternating iterative solutions. This is one of the key points of this invention to ensure the numerical stability of the algorithm and suppress numerical oscillations when performing iterative solutions.

[0099] In the specific implementation, during the solution process, combining linear interpolation and using the second simulation step size for calculation, it can be:

[0100] First, obtain the system algebraic variable vector of SVG at time n. and the system algebraic variable vector at time n+1 ;

[0101] Next, a linear interpolation method is used, based on the system algebraic variable vector at time n. The system algebraic variable vector at time n+1 Second simulation step size With the first simulation step size Positive integer ratio between Calculate the second simulation step size (i.e., each time step) of the SVG in the k-th iteration at time n+1. Intermediate values ​​of system algebraic variable vectors .

[0102] Step S023: For power equipment in the power system other than SVG, adopt the first simulation step size and solve the second system state variable vector and the second node injection current vector at time n+1 through the second difference equation system.

[0103] For iterative solutions of other power equipment in the system, equation (5) can be rewritten as equation (9) for iterative solution:

[0104] (9)

[0105] Step S03: Substitute the first system state variable vector and the first node injected current vector into the node voltage equation at time n+1, and solve for the first system algebraic variable vector at time n+1. Substitute the second system state variable vector and the second node injected current vector into the node voltage equation at time n+1, and solve for the second system algebraic variable vector at time n+1.

[0106] The result obtained through step S02 and Substitute into equation (6) to calculate the first system algebraic variable vector corresponding to the SVG at time n+1. Other electrical equipment in the system .

[0107] Step S04: Determine whether the algebraic variable vectors of the first system and the algebraic variable vectors of the second system meet the preset error conditions, and execute the subsequent iterative solution process based on the error judgment results.

[0108] Based on the preceding content, a small-step simulation was used to solve the fast dynamic process of SVG. After several small-step simulations, it was integrated with the conventional slow dynamic process. For the iterative solution process at each time step, assuming that the solution of the fast dynamic process does not participate in the convergence judgment of the slow dynamic process solution, it is also very easy to cause oscillation problems.

[0109] Therefore, when the k iterations at time n+1 are completed, it is necessary to determine the calculated first system algebraic variable vector. With the second system algebraic variable vector Whether the preset error conditions are met, and based on the error judgment result, execute the subsequent iterative solution process. Specifically, this step can be: determining whether the first system's algebraic variable vectors are met. With the second system algebraic variable vector If all conditions are met, convergence occurs at time n+1. Set k=0 and continue the alternating iterative solution process at time n+2 according to steps S01 to S04. If not, set k=k+1 and continue the alternating iterative solution process at time n+1 according to steps S02 to S04.

[0110] In this embodiment of the invention, a fast-slow dynamic process alternating solution method is proposed, which considers the fast dynamic process iteration of SVG during the slow dynamic process iteration. First, the system state variables, system algebraic variables, and node injection currents of the power system during transient simulation are simultaneously considered to construct an electromechanical transient simulation model of the power system. Then, the electromechanical transient simulation model is differentially processed based on the implicit trapezoidal integral method to obtain the iterative equation at time n+1. Finally, the iterative equation at time n+1 is solved alternately iteratively with linear interpolation to obtain the transient simulation solution result of the power system. Thus, in the original alternating solution process of the differential-algebraic equation system, the alternating solution of the fast-slow dynamic process is further introduced, combined with linear interpolation, forming an alternating iterative solution process that simultaneously considers both the system-algebraic level and the SVG (fast)-other power equipment (slow) level. This ensures that the structure of the implicit trapezoidal integral in the SVG fast dynamic process is not destroyed during the solution process, effectively suppressing the numerical oscillation problem in the electromechanical transient simulation of the power system caused by the introduction of SVG.

[0111] For better explanation, refer to Figure 3 This diagram illustrates the overall flow of a numerical oscillation suppression method for electromechanical transient simulation using SVG, provided by an embodiment of the present invention. It should be noted that this embodiment only provides a brief overview of the general flow of numerical oscillation suppression for electromechanical transient simulation using SVG. The specific implementation process of each step can be understood by referring to the relevant content in the foregoing embodiments, and will not be elaborated upon here. It is understood that the present invention does not impose any limitations on this.

[0112] Step 301: Simultaneously consider the system state variables, system algebraic variables, and node injection currents of the power system during the transient simulation process, construct the first transient simulation equation set of the SVG, and the second transient simulation equation set of the power equipment other than the SVG in the power system; obtain the node admittance matrix of the power system, and construct the node voltage equation of the power system based on the node admittance matrix.

[0113] Step 302: Using the implicit trapezoidal integration method, perform difference processing on the first transient simulation equation set and the second transient simulation equation set respectively to obtain the first difference equation set corresponding to the first transient simulation equation set and the second difference equation set corresponding to the second transient simulation equation set; construct the node voltage equation at time n+1.

[0114] Step 303: Start the alternating iterative solution at time n+1. When k=0, initialize the initial values ​​of the system algebraic variable vector in the node voltage equation at time n+1.

[0115] Step 304: When k≠0, combine linear interpolation and consider the simulation step size difference, solve the first system state variable vector and the first node injection current vector at time n+1 through the first difference equation system, and solve the second system state variable vector and the second node injection current vector at time n+1 through the second difference equation system.

[0116] Step 305: Substitute the first system state variable vector and the first node injected current vector into the node voltage equation at time n+1, and solve for the first system algebraic variable vector at time n+1. Substitute the second system state variable vector and the second node injected current vector into the node voltage equation at time n+1, and solve for the second system algebraic variable vector at time n+1.

[0117] Step 306: Determine whether the algebraic variable vectors of the first system and the algebraic variable vectors of the second system meet the preset error conditions, and execute the subsequent iterative solution process based on the error judgment results;

[0118] Step 307: Complete all alternating iterative solutions to obtain the transient simulation results of the power system.

[0119] Reference Figure 4 The diagram illustrates a structural block diagram of a numerical oscillation suppression device for electromechanical transient simulation of SVG, provided by an embodiment of the present invention. Specifically, it may include:

[0120] The model building unit 401 is used to simultaneously consider the system state variables, system algebra variables and node injection currents of the power system in the transient simulation process, and to build the electromechanical transient simulation model of the power system.

[0121] Differentiation processing unit 402 is used to perform differential processing on the electromechanical transient simulation model to obtain the iterative equation at time n+1.

[0122] The alternating iterative solution unit 403 is used to perform alternating iterative solution of the iterative equation at time n+1 combined with linear interpolation to obtain the transient simulation solution result of the power system.

[0123] In one alternative embodiment, the model building unit 401 includes:

[0124] The transient simulation equation system construction unit is used to simultaneously consider the system state variables, system algebraic variables, and node injection currents of the power system during the transient simulation process, and construct the first transient simulation equation system of the SVG in the form of differential-algebraic equation system, and simultaneously construct the second transient simulation equation system of the power equipment other than the SVG in the power system.

[0125] A node voltage equation construction unit is used to obtain the node admittance matrix of the power system and construct the node voltage equations of the power system based on the node admittance matrix.

[0126] The electromechanical transient simulation model integration unit is used to integrate the first transient simulation equation set, the second transient simulation equation set, and the node voltage equation into the electromechanical transient simulation model of the power system.

[0127] In one alternative embodiment, the differential processing unit 402 includes:

[0128] The difference processing subunit is used to obtain a pre-set first simulation step size. Based on the first simulation step size, the implicit trapezoidal integral method is used to perform difference processing on the first transient simulation equation set and the second transient simulation equation set respectively to obtain the first difference equation set corresponding to the first transient simulation equation set and the second difference equation set corresponding to the second transient simulation equation set.

[0129] The node voltage equation construction unit at time n+1 is used to construct the node voltage equation at time n+1.

[0130] The n+1 time iteration equation integration unit is used to integrate the first difference equation set, the second difference equation set, and the n+1 time node voltage equation into an n+1 time iteration equation.

[0131] In one alternative embodiment, the alternating iterative solution unit 403 includes:

[0132] An iterative initialization unit is used to execute step S01: when k=0, initialize the iterative initial value of the system algebraic variable vector in the node voltage equation at time n+1;

[0133] The difference equation solving unit is used to execute step S02: when k≠0, combined with linear interpolation and considering the simulation step size difference, the first system state variable vector and the first node injection current vector at time n+1 are solved by the first difference equation system, and the second system state variable vector and the second node injection current vector at time n+1 are solved by the second difference equation system.

[0134] The system algebraic variable vector solving unit is used to execute step S03: substituting the first system state variable vector and the first node injection current vector into the node voltage equation at time n+1 to solve the first system algebraic variable vector at time n+1; substituting the second system state variable vector and the second node injection current vector into the node voltage equation at time n+1 to solve the second system algebraic variable vector at time n+1.

[0135] The error judgment unit is used to execute step S04: determine whether the first system algebraic variable vector and the second system algebraic variable vector meet the preset error conditions, and execute the subsequent iterative solution process based on the error judgment result.

[0136] In one optional embodiment, the difference equation solving unit includes:

[0137] The second simulation step size determination unit is used to determine the second simulation step size based on the first simulation step size, wherein the second simulation step size is smaller than the first simulation step size, and the first simulation step size and the second simulation step size are in a positive integer proportional relationship.

[0138] The first difference equation solving subunit is used to solve the first system state variable vector and the first node injection current vector at time n+1 for the SVG through the first difference equation system, and in the solution process, linear interpolation is combined with the second simulation step size for calculation.

[0139] The second difference equation solving subunit is used to solve the second system state variable vector and the second node injection current vector at time n+1 for power equipment in the power system other than the SVG, using the first simulation step size and the second difference equation system.

[0140] In one optional embodiment, the first solution subunit for the difference equations includes:

[0141] The vector data acquisition unit is used to acquire the system algebraic variable vector at time n and the system algebraic variable vector at time n+1 of the SVG;

[0142] The linear interpolation calculation unit is used to calculate the intermediate value of the system algebraic variable vector of the SVG at each of the second simulation step sizes in the k-th iteration at time n+1, based on the system algebraic variable vector at time n+1, the system algebraic variable vector at time n+1, and the positive integer ratio between the second simulation step size and the first simulation step size, using a linear interpolation method.

[0143] In one optional embodiment, the calculation error judgment unit is specifically used for:

[0144] Determine whether the algebraic variable vectors of the first system and the algebraic variable vectors of the second system both meet the preset error requirements;

[0145] If so, let k=0, and continue the alternating iterative solution process at time n+2 according to steps S01 to S04;

[0146] If not, then continue with steps S02 to S04 to execute the (k+1)th alternating iteration solution process at time n+1.

[0147] As the device embodiment is basically similar to the method embodiment, it is described in a relatively simple way. For relevant details, please refer to the description of the method embodiment above.

[0148] It should be noted that, in order to enable those skilled in the art to better distinguish data of the same type but with different actual meanings, the embodiments of the present invention use "first" and "second" to distinguish and describe some technical features. "First" and "second" are only used to distinguish data and have no other special meaning. It is understood that the present invention does not impose any limitations on them.

[0149] This invention also provides an electronic device, which includes a processor and a memory:

[0150] The memory is used to store program code and transfer the program code to the processor;

[0151] The processor is used to execute, according to instructions in the program code, a numerical oscillation suppression method for electromechanical transient simulation of SVG according to any embodiment of the present invention.

[0152] This invention also provides a computer-readable storage medium for storing program code for executing a numerical oscillation suppression method for electromechanical transient simulation of SVG according to any embodiment of the invention.

[0153] 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.

[0154] In the embodiments provided by this invention, 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 devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0155] 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.

[0156] Furthermore, the functional units in the various embodiments of the present invention 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.

[0157] 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 the present invention, 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 the present invention. 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.

[0158] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention 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 the present invention.

Claims

1. A numerical oscillation suppression method suitable for electromechanical transient simulation of SVG, characterized in that, include: Simultaneously considering the system state variables, system algebraic variables, and node injection currents of the power system during transient simulation, an electromechanical transient simulation model of the power system is constructed. The electromechanical transient simulation model is differentially processed to obtain the iterative equation at time n+1; The transient simulation results of the power system are obtained by performing alternating iterative solutions to the iterative equation at time n+1 using linear interpolation. The alternating iterative solution at time n+1 includes two levels. The first level of alternating iterative solution is the alternating solution of the system difference equation and the algebraic equation. The second level of alternating iterative solution is the dynamic alternating solution between the SVG and other power equipment in the power system. During the solution process, the slow dynamic process of the other power equipment is calculated using a first simulation step size, and the fast dynamic process of the SVG is calculated using a second simulation step size. While using the first simulation step size in the slow dynamic process, the first simulation step size is divided into multiple second simulation step sizes on average, and the second simulation step size is set as the iteration step of the fast dynamic process. Furthermore, linear interpolation is combined to perform alternating iterative solutions.

2. The numerical oscillation suppression method according to claim 1, characterized in that, The electromechanical transient simulation model of the power system is constructed by simultaneously considering the system state variables, system algebraic variables, and node injection currents during the transient simulation process, including: Simultaneously considering the system state variables, system algebraic variables, and node injection currents of the power system during the transient simulation process, the first transient simulation equation set of the SVG is constructed in the form of differential-algebraic equations, and the second transient simulation equation set of the power equipment other than the SVG in the power system is also constructed. Obtain the node admittance matrix of the power system, and construct the node voltage equations of the power system based on the node admittance matrix; The first transient simulation equation set, the second transient simulation equation set, and the node voltage equations are integrated into the electromechanical transient simulation model of the power system.

3. The numerical oscillation suppression method according to claim 2, characterized in that, The differential processing of the electromechanical transient simulation model to obtain the iterative equation at time n+1 includes: A pre-set first simulation step size is obtained. Based on the first simulation step size, the implicit trapezoidal integral method is used to perform difference processing on the first transient simulation equation set and the second transient simulation equation set respectively, to obtain the first difference equation set corresponding to the first transient simulation equation set and the second difference equation set corresponding to the second transient simulation equation set. Construct the node voltage equation at time n+1; The first set of difference equations, the second set of difference equations, and the node voltage equation at time n+1 are integrated into an iterative equation at time n+1.

4. The numerical oscillation suppression method according to claim 3, characterized in that, For the k-th iteration at time n+1, the alternating iterative solution process combining linear interpolation includes: Step S01: When k=0, initialize the initial values ​​of the system algebraic variable vector in the node voltage equation at time n+1; Step S02: When k≠0, combine linear interpolation and consider the simulation step size difference, solve the first system state variable vector and the first node injection current vector at time n+1 through the first difference equation system, and solve the second system state variable vector and the second node injection current vector at time n+1 through the second difference equation system. Step S03: Substitute the first system state variable vector and the first node injected current vector into the node voltage equation at time n+1 to solve for the first system algebraic variable vector at time n+1; substitute the second system state variable vector and the second node injected current vector into the node voltage equation at time n+1 to solve for the second system algebraic variable vector at time n+1. Step S04: Determine whether the algebraic variable vector of the first system and the algebraic variable vector of the second system meet the preset error conditions, and execute the subsequent iterative solution process based on the error judgment result.

5. The numerical oscillation suppression method according to claim 4, characterized in that, The method of combining linear interpolation, while considering simulation step size differences, to solve for the first system state variable vector and the first node injected current vector at time n+1 using the first difference equation system, and to solve for the second system state variable vector and the second node injected current vector at time n+1 using the second difference equation system, includes: The second simulation step size is determined based on the first simulation step size. The second simulation step size is smaller than the first simulation step size, and the first simulation step size and the second simulation step size are in a positive integer proportional relationship. For the SVG, the first system state variable vector and the first node injection current vector at time n+1 are solved by the first difference equation system, and in the solution process, linear interpolation is combined with the second simulation step size for calculation. For the power equipment in the power system other than the SVG, the first simulation step size is used, and the second system state variable vector and the second node injection current vector at time n+1 are solved by the second difference equation system.

6. The numerical oscillation suppression method according to claim 5, characterized in that, The process of solving the problem, which combines linear interpolation and uses the second simulation step size for calculation, includes: Obtain the system algebraic variable vector at time n and the system algebraic variable vector at time n+1 of the SVG; Using linear interpolation, based on the system algebraic variable vector at time n, the system algebraic variable vector at time n+1, and the positive integer ratio between the second simulation step size and the first simulation step size, the intermediate value of the system algebraic variable vector of the SVG at each of the second simulation step sizes in the k-th iteration at time n+1 is calculated one by one.

7. The numerical oscillation suppression method according to any one of claims 4 to 6, characterized in that, The step of determining whether the algebraic variable vectors of the first system and the second system satisfy a preset error condition, and executing subsequent iterative solution processes based on the error determination results, includes: Determine whether the algebraic variable vectors of the first system and the algebraic variable vectors of the second system both meet the preset error requirements; If so, let k=0, and continue the alternating iterative solution process at time n+2 according to steps S01 to S04; If not, then continue with steps S02 to S04 to execute the (k+1)th alternating iteration solution process at time n+1.

8. A numerical oscillation suppression device suitable for electromechanical transient simulation of SVG, characterized in that, include: The model building unit is used to simultaneously consider the system state variables, system algebraic variables, and node injection currents of the power system during the transient simulation process, and to build the electromechanical transient simulation model of the power system. The differential processing unit is used to perform differential processing on the electromechanical transient simulation model to obtain the iterative equation at time n+1. The alternating iterative solution unit is used to perform alternating iterative solution of the iterative equation at time n+1, combined with linear interpolation, to obtain the transient simulation solution result of the power system. The alternating iterative solution at time n+1 includes two levels. The first level of alternating iterative solution is the alternating solution of the system difference equation and the algebraic equation. The second level of alternating iterative solution is the dynamic alternating solution between the SVG and other power equipment in the power system. During the solution process, the slow dynamic process of the other power equipment is calculated using a first simulation step size, and the fast dynamic process of the SVG is calculated using a second simulation step size. While using the first simulation step size in the slow dynamic process, the first simulation step size is divided into multiple second simulation step sizes on average, and the second simulation step size is set as the iteration step of the fast dynamic process. Furthermore, linear interpolation is combined to perform alternating iterative solutions.

9. An electronic device, characterized in that, The device includes a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute, according to instructions in the program code, the numerical oscillation suppression method for electromechanical transient simulation of SVG as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store program code for executing the numerical oscillation suppression method for electromechanical transient simulation of SVG as described in any one of claims 1-7.

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