Numerical oscillation suppression method suitable for electromechanical transient simulation of SVG (Static Var Generator)

Abstract

The invention discloses a numerical oscillation suppression method suitable for electromechanical transient simulation of an SVG (Static Var Generator). The numerical oscillation suppression method is used for solving the problem of numerical oscillation caused by introduction of the SVG in the electromechanical transient simulation process. The method comprises the following steps: firstly, simultaneously considering a system state variable, a system algebraic variable and a node injection current of a power system in a transient simulation process, and constructing an electromechanical transient simulation model of the power system; carrying out difference processing on the electromechanical transient simulation model to obtain an (n + 1) moment iterative equation; and finally, carrying out alternating iteration solution combined with linear interpolation on the iteration equation at the n + 1 moment to obtain a transient simulation solution result of the power system. Therefore, in an original differential-algebraic equation set alternative solution process, alternative solution combined with linear interpolation is further introduced, so that the structure of the implicit trapezoidal integral in the SVG fast dynamic process is not damaged in the solution process, and the electromechanical transient simulation numerical oscillation problem caused by SVG introduction of a power system can be effectively inhibited.

Description

Technical Field

[0001] The present invention relates to the technical field of power simulation, 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 Art

[0002] With the large-scale access of new energy and power electronic devices to 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 that is widely used in modern power systems to improve power quality and enhance the stability of transmission systems. SVG can provide or absorb a large amount of reactive current within milliseconds by quickly responding to and accurately controlling the output of reactive power, thereby effectively regulating the grid voltage, suppressing harmonics, and compensating for unbalanced loads.

[0003] The commonly used solution algorithm in existing electromechanical transient simulation tools is the alternating solution algorithm based on implicit trapezoidal integration. However, in the electromechanical transient simulation process, the power electronic devices represented by SVG have a large difference in the time constant of the fast dynamic link of the control process compared with the slow dynamic link time constant of the traditional synchronous machine (the fast dynamic process time constant of SVG is much smaller than the slow dynamic process time constant of the synchronous generator system), which enhances the rigidity of the electromechanical transient simulation process, resulting in the electromechanical transient simulation in the scenario of a high proportion of power electronic devices. Numerical oscillation problems are very likely to occur. Therefore, it is urgent to improve the existing electromechanical SVG transient simulation algorithm to suppress the numerical oscillation problem introduced by SVG during the simulation process. Summary of the invention

[0004] The present invention provides 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, which are used to solve or partially solve the numerical oscillation problem caused by the introduction of SVG in the electromechanical transient simulation process.

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

[0006] Simultaneously, the system state variables, system algebraic variables and node injection current of the power system during the transient simulation process are considered to construct an electromechanical transient simulation model of the power system;

[0007] Performing a difference process on the electromechanical transient simulation model to obtain an iterative equation at time n+1;

[0008] The n+1 time iterative equation is solved by alternating iteration combined with linear interpolation to obtain a transient simulation solution result of the power system.

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

[0010] At the same time, considering the system state variables, system algebraic variables and node injection current of the power system during the transient simulation process, a first transient simulation equation group of the SVG is constructed in the form of a differential-algebraic equation group, and a second transient simulation equation group of the power equipment other than the SVG in the power system is constructed;

[0011] Acquire a node admittance matrix of the power system, and construct a node voltage equation of the power system based on the node admittance matrix;

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

[0013] Optionally, performing a difference process on the electromechanical transient simulation model to obtain an iterative equation at time n+1 includes:

[0014] Obtaining a preset first simulation step size, and based on the first simulation step size, using an implicit trapezoidal integration method to perform difference processing on the first transient simulation equation group and the second transient simulation equation group, respectively, to obtain a first difference equation group corresponding to the first transient simulation equation group, and a second difference equation group corresponding to the second transient simulation equation group;

[0015] Constructing a node voltage equation at time n+1 of the node voltage equation;

[0016] The first differential equation group, the second differential equation group 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 combined with linear interpolation includes:

[0018] Step S01: when k=0, initializing the iterative initial value of the system algebraic variable vector in the node voltage equation at the time n+1;

[0019] Step S02: when k≠0, combining linear interpolation and considering the simulation step size difference, solving the first system state variable vector and the first node injection current vector at time n+1 by the first differential equation group, and solving the second system state variable vector and the second node injection current vector at time n+1 by the second differential equation group;

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

[0021] Step S04: determining whether the first system algebraic variable vector and the second system algebraic variable vector meet a preset error condition, and executing a subsequent iterative solution process based on the error determination result.

[0022] Optionally, the combining linear interpolation and considering the simulation step size difference at the same time, solving the first system state variable vector and the first node injection current vector at the time n+1 by the first differential equation group, and solving the second system state variable vector and the second node injection current vector at the time n+1 by the second differential equation group, comprises:

[0023] Determining a second simulation step length according to the first simulation step length, wherein the second simulation step length is smaller than the first simulation step length, and the first simulation step length and the second simulation step length are in a positive integer proportional relationship;

[0024] For the SVG, solving the first system state variable vector and the first node injection current vector at time n+1 by using the first differential equation group, and in the solving process, combining linear interpolation and using the second simulation step size for calculation;

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

[0026] Optionally, in the solving process, combining linear interpolation and using the second simulation step size for calculation includes:

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

[0028] By adopting a linear interpolation method, based on the system algebraic variable vector at time n, the system algebraic variable vector at time n+1, and the positive integer proportional relationship between the second simulation step and the first simulation step, the intermediate values ​​of the system algebraic variable vector of each second simulation step of the SVG in the k-th iteration at time n+1 are calculated one by one.

[0029] Optionally, the determining whether the first system algebraic variable vector and the second system algebraic variable vector meet a preset error condition, and executing a subsequent iterative solution process based on an error determination result, includes:

[0030] Determining whether the first system algebraic variable vector and the second system algebraic variable vector both meet a preset error requirement;

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

[0032] If not, continue to execute the k+1th alternating iterative solution process at time n+1 according to steps S02 to S04.

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

[0034] A model building unit, used to simultaneously consider the system state variables, system algebraic variables and node injection current of the power system during the transient simulation process to build an electromechanical transient simulation model of the power system;

[0035] A differential processing unit, used for performing differential processing on the electromechanical transient simulation model to obtain an iterative equation at time n+1;

[0036] The alternating iterative solution unit is used to perform alternating iterative solution combined with linear interpolation on the n+1 time iterative equation to obtain a 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 used to execute the numerical oscillation suppression method for electromechanical transient simulation applicable to SVG as described in any one of the above items according to the instructions in the program code.

[0040] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program codes, wherein the program codes are used to execute the numerical oscillation suppression method for electromechanical transient simulation applicable to SVG as described in any one of the above items.

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

[0042] A numerical oscillation suppression method for electromechanical transient simulation suitable for SVG is provided. Firstly, the system state variables, system algebraic variables and node injection current of the power system in the transient simulation process are considered simultaneously to construct an electromechanical transient simulation model of the power system; then, the electromechanical transient simulation model is differentiated to obtain the n+1 time iterative equation; finally, the n+1 time iterative equation is solved by alternating iteration combined with linear interpolation to obtain the transient simulation solution of the power system. Therefore, in the alternating solution process of the original differential-algebraic equation group, the alternating solution combined with linear interpolation is further introduced, so that the structure of the implicit trapezoidal integral in the SVG fast dynamic process will not be destroyed in the solution process, which can effectively suppress the numerical oscillation problem of electromechanical transient simulation of the power system caused by the introduction of SVG. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0045] Figure 2 It is a block diagram of the transfer function of a constant voltage controlled SVG;

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

[0047] Figure 4 The structure block diagram of a numerical oscillation suppression device suitable for electromechanical transient simulation of SVG. DETAILED DESCRIPTION

[0048] Embodiments of the present invention provide 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, 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] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] As an example, the commonly used solution algorithm of existing electromechanical transient simulation tools is the alternating solution algorithm based on implicit trapezoidal integration. However, in the electromechanical transient simulation process, the power electronic devices represented by SVG have a large difference in the time constant of the fast dynamic link of the control process compared with the time constant of the slow dynamic link of the traditional synchronous machine (the fast dynamic process time constant of SVG is much smaller than the slow dynamic process time constant of the synchronous generator system), which enhances the rigidity of the electromechanical transient simulation process, resulting in the electromechanical transient simulation in the scenario of a high proportion of power electronic devices. It is very easy to produce numerical oscillation problems. Therefore, it is urgent to improve the existing electromechanical SVG transient simulation algorithm to suppress the numerical oscillation problem introduced by SVG during the simulation process.

[0051] Therefore, one of the core invention points of the embodiment of the present invention is: in view of the shortcomings of the current technology, a method for alternating the solution of the fast-slow dynamic process that considers the iteration of the SVG fast dynamic process in the iterative process of the slow dynamic process is proposed. First, the system state variables, system algebraic variables and node injection current of the power system in the transient simulation process are considered at the same time to construct an electromechanical transient simulation model of the power system; then, the electromechanical transient simulation model is differentiated based on the implicit trapezoidal integration method to obtain the n+1 moment iterative equation; finally, the n+1 moment iterative equation is solved by alternating iteration combined with linear interpolation to obtain the transient simulation solution result of the power system. Therefore, in the alternating solution process of the original differential-algebraic equation group, the alternating solution of the fast-slow dynamic process is further introduced, and at the same time, combined with linear interpolation, an alternating iterative solution process is formed that considers the system-algebraic level and the SVG (fast)-system other power equipment (slow) level. The structure of the implicit trapezoidal integral in the SVG fast dynamic process will not be destroyed during the solution process, and the numerical oscillation problem of electromechanical transient simulation caused by the introduction of SVG in the power system can be effectively suppressed.

[0052] In the embodiment of the present invention, the power system that needs to perform transient simulation is connected to an SVG with fast dynamic process characteristics. Figure 1 , shows a flowchart of a numerical oscillation suppression method for electromechanical transient simulation of SVG provided by an embodiment of the present invention, which may specifically include the following steps:

[0053] Step 101, constructing an electromechanical transient simulation model of the power system by simultaneously considering the system state variables, system algebraic variables and node injection current of the power system during the transient simulation process;

[0054] This step mainly realizes the construction of an electromechanical transient simulation model of the power system containing SVG.

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

[0056] Step 1011: Considering the system state variables, system algebraic variables and node injection current of the power system in the transient simulation process, a first transient simulation equation group of the SVG is constructed in the form of a differential-algebraic equation group, and a second transient simulation equation group of the power equipment other than the SVG in the power system is constructed at the same time;

[0057] The mathematical model of the 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] In order to distinguish SVG from other power equipment in the power system, the differential-algebraic equation group represented by formula (1) is used as the first transient simulation equation group of SVG, and the differential-algebraic equation group represented by formula (2) is used as the second transient simulation equation group of power equipment other than SVG in the power system.

[0061] In formula (1) and formula (2), is the system state variable vector; is the system algebraic variable vector; Inject current vector into the node; is the time constant vector of the dynamic process; is the differential equations of the system dynamic process; is a system of algebraic equations; subscript Indicates that state variables and algebraic variables belong to SVG; subscript It indicates that the state variables and algebraic variables belong to the power equipment part of the power system except SVG. The “·” above means About Time Find the derivative.

[0062] Taking the SVG with constant voltage control in 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.

[0063] Among them, the input of constant voltage control is the SVG constant voltage control node voltage , constant voltage control reference voltage , Auxiliary input signal , grid connection point voltage ; Output is the reactive current injected by SVG into the system ; is the time constant of the measurement link; , is the time constant of the first-stage lead-lag link; , is the time constant of the second-stage lead-lag link; is the time constant of the proportional link; is the time constant of the SVG response delay link; , are the magnifications of the proportional link and the integral link respectively; is the slope of the VI characteristic of SVG; , , , , , To limit the voltage and current of each link; is the equivalent reactance between SVG and the grid connection point.

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

[0065] In formula (1) and (2), , At the same time, the network equation (node ​​voltage equation) shown in formula (3) is satisfied:

[0066] (3)

[0067] in, is the node admittance matrix of the system.

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

[0069] Step 102, performing a difference process on the electromechanical transient simulation model to obtain an iterative equation at time n+1;

[0070] This step mainly differentiates the equation constructed above and constructs the n+1 time iterative equation.

[0071] In some embodiments, the electromechanical transient simulation model is differentiated to obtain the process of iterative equation at time n+1, including the following sub-steps 1021 to 1023:

[0072] Step 1021: obtaining a preset first simulation step size, and based on the first simulation step size, using an implicit trapezoidal integration method to perform difference processing on the first transient simulation equation group and the second transient simulation equation group, respectively, to obtain a first difference equation group corresponding to the first transient simulation equation group, and a second difference equation group corresponding to the second transient simulation equation group;

[0073] In order to distinguish it from the small step size used in the following steps, the preset system simulation step size is defined as the first simulation step size. Assume that the first simulation step size is , using implicit trapezoidal integration method to perform difference processing on equations (1) and (2), we can obtain the first difference equation group corresponding to SVG as shown in equation (4), and the second difference equation group for the rest of the system as shown in equation (5):

[0074] (4)

[0075] (5)

[0076] Step 1022: constructing a node voltage equation at time n+1;

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

[0078] (6)

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

[0080] Step 103, performing alternating iterative solutions in combination with linear interpolation on the iterative equation at time n+1 to obtain transient simulation solution results of the power system.

[0081] This step mainly realizes the alternating iterative solution of the iterative equation at time n+1 to obtain the final transient simulation result. Among them, for the entire solution process, the alternating iterative solution at time n+1 can include two levels. The first level of alternating iterative solution is the alternating solution of the system differential equation and the algebraic equation. The second level of alternating iterative solution is the dynamic alternating solution of the rest of the system and the SVG part.

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

[0083] 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;

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

[0085] Step S02: when k≠0, combining linear interpolation and considering the simulation step size difference, solving the first system state variable vector and the first node injection current vector at time n+1 by the first differential equation group, and solving the second system state variable vector and the second node injection current vector at time n+1 by the second differential equation group;

[0086] Step S02 mainly solves the first system state variable vector at time n+1 by using equations (4) and (5): , the first node injection current vector and the second system state variable vector , the second node injection current vector .

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

[0088] Step S021: determining a second simulation step length according to the first simulation step length, wherein the second simulation step length is smaller than the first simulation step length, and the first simulation step length and the second simulation step length are in a positive integer proportional relationship;

[0089] Since the time constant of the SVG fast dynamic process in equation (4) Much smaller than the time constant of the dynamic link of other power equipment in the system Therefore, when solving the problem, a small step size should be used for the fast dynamic process of SVG. (second simulation step) for calculation, and large step size is used for the slow dynamic process of other components of the system (first simulation step) to perform the calculation. At the same time, let the large step size and small step length Maintain positive integer ratio That's it.

[0090] Step S022: for the SVG, solving the first system state variable vector and the first node injection current vector at time n+1 by using the first differential equation group, and in the solving process, combining linear interpolation and using the second simulation step size for calculation;

[0091] For fast dynamic processes in SVG, a small step size is used When performing simulation, the corresponding formula (4) needs to be rewritten as the following formula (7):

[0092] (7)

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

[0094] It can be seen that in the embodiment of the present invention, the setting of large and small step sizes is equivalent to setting a large time step The average is Small step length In the subsequent time step In the process of iterative value taking, no matter What value to take? All meet For example, assuming a large step size Second, seconds. When calculating the dynamic process of 0 to 1 second, for the slow dynamic process corresponding to other power equipment in the system (i.e., the subscript The corresponding correlation equation is For the fast dynamic process of SVG (i.e., the subscript The corresponding correlation equation), due to seconds, it is necessary to gradually calculate 0.1, 0.2, 0.3...0.9 until 1.0. Therefore, the fast dynamic process contains a total of 10 calculations of formula (7), corresponding to Take 1, 2, 3,...10.

[0095] According to formula (7), the fast dynamic process of SVG is continuously calculated After time steps, the value obtained is the value of the SVG-related variable at the kth iteration at time n+1. , , at this time, equation (6) can be used to calculate the node voltage equation of the whole system at time n+1.

[0096] In actual situations, we use formula (7) to continuously calculate When the fast dynamic process of SVG is a time-step process, the algebraic variables in the formula , According to the previous step S01, the SVG fast dynamic process can be calculated The value of (equivalent to the k-time fast dynamic process of SVG at time n+1, which has not yet been measured in time steps The initial value when the iterative calculation starts) can be used by linear interpolation method, combined with as well as The values ​​of the intermediate time steps of all fast dynamic processes are obtained by calculation ,Right now:

[0097] (8)

[0098] For the calculation of each time step of the fast dynamic process, the interpolation calculation of each time step in the SVG fast dynamic process can be obtained by equation (8): of , so that the implicit trapezoidal integral structure of equation (7) is not destroyed. While the slow dynamic process adopts a large time step, the large time step is evenly divided into multiple small steps, and it is set as the iterative time step of the fast dynamic process, and further combined with linear interpolation for alternating iterative solution. This is one of the key points of the present invention to ensure the numerical stability of the algorithm and suppress numerical oscillation when performing iterative solution.

[0099] In the specific implementation, in the solution process, linear interpolation is combined and the second simulation step is used for calculation, which can be:

[0100] First, get the n-time system algebraic variable vector of SVG And the algebraic variable vector of the system at time n+1 ;

[0101] Then, linear interpolation is used based on the algebraic variable vector of the system at time n 、The algebraic variable vector of the system at time n+1 , the second simulation step With the first simulation step The positive integer ratio relationship between , calculate each second simulation step length (i.e. each time step) of SVG in the kth iteration at time n+1 one by one ) of the system algebraic variable vector intermediate value .

[0102] Step S023: For the power equipment other than the SVG in the power system, the first simulation step is adopted, and the second system state variable vector and the second node injection current vector at time n+1 are solved by the second differential equation group.

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

[0104] (9)

[0105] Step S03: Substitute 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, substitute 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;

[0106] The result calculated in step S02 and Substituting into equation (6), we can calculate the first system algebraic variable vector corresponding to SVG at time n+1: 、Corresponding to other power equipment parts of the system .

[0107] Step S04: determining whether the first system algebraic variable vector and the second system algebraic variable vector meet a preset error condition, and executing a subsequent iterative solution process based on the error determination result.

[0108] Combined with the previous content, a small step size simulation is used to solve the fast dynamic process of SVG, and after several small step size simulations, it is connected with the conventional slow dynamic process. For the iterative solution process at each moment, assuming that the solution of the fast dynamic process does not participate in the convergence judgment of the solution of the slow dynamic process, it is also very easy to cause oscillation problems.

[0109] Therefore, when k iterations are completed at time n+1, it is necessary to determine the first system algebraic variable vector calculated With the second system of algebraic variables vector Whether it meets the preset error conditions, and based on the error judgment result, execute the subsequent iterative solution process. This step can be specifically: determine whether the first system algebraic variable vector With the second system of algebraic variables vector Whether they all meet the preset error requirements; if so, converge at time n+1, set k=0, and continue to execute the alternating iterative solution process at time n+2 according to steps S01 to S04; if not, set k=k+1, and continue to execute the k+1th alternating iterative solution process at time n+1 according to steps S02 to S04.

[0110] In an embodiment of the present invention, a fast-slow dynamic process alternating solution method is proposed that considers the iteration of the SVG fast dynamic process in the slow dynamic process iteration process. First, the system state variables, system algebraic variables and node injection current of the power system in the transient simulation process are considered simultaneously to construct an electromechanical transient simulation model of the power system; then, the electromechanical transient simulation model is differentiated based on the implicit trapezoidal integration method to obtain the n+1 moment iteration equation; finally, the n+1 moment iteration equation is solved by alternating iteration combined with linear interpolation to obtain the transient simulation solution result of the power system. Thus, in the alternating solution process of the original differential-algebraic equation group, the alternating solution of the fast-slow dynamic process is further introduced, and at the same time, linear interpolation is combined to form an alternating iterative solution process that considers both the system-algebraic level and the SVG (fast)-system other power equipment (slow) level, so that the implicit trapezoidal integral structure of the SVG fast dynamic process will not be destroyed during the solution process, and the numerical oscillation problem of electromechanical transient simulation caused by the introduction of SVG in the power system can be effectively suppressed.

[0111] For better explanation, refer to Figure 3 , showing a schematic diagram of the overall process of a numerical oscillation suppression method for electromechanical transient simulation of SVG provided by an embodiment of the present invention. It should be pointed out that this embodiment only briefly describes the general process of numerical oscillation suppression of electromechanical transient simulation containing SVG, and the specific implementation process of each step can be understood by referring to the relevant content in the aforementioned embodiment, which will not be described here. It can be understood that the present invention is not limited to this.

[0112] Step 301: Considering the system state variables, system algebraic variables and node injection current of the power system in the transient simulation process, a first transient simulation equation group of the SVG and a second transient simulation equation group of the power equipment other than the SVG in the power system are constructed; a node admittance matrix of the power system is obtained, and a node voltage equation of the power system is constructed based on the node admittance matrix;

[0113] Step 302: using an implicit trapezoidal integration method, performing difference processing on the first transient simulation equation group and the second transient simulation equation group, respectively, to obtain a first difference equation group corresponding to the first transient simulation equation group, and a second difference equation group corresponding to the second transient simulation equation group; constructing a node voltage equation at time n+1 of the node voltage equation;

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

[0115] Step 304: when k≠0, combining linear interpolation and considering the simulation step size difference, solving the first system state variable vector and the first node injection current vector at time n+1 by the first differential equation group, and solving the second system state variable vector and the second node injection current vector at time n+1 by the second differential equation group;

[0116] Step 305: Substitute 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, substitute 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;

[0117] Step 306: determining whether the first system algebraic variable vector and the second system algebraic variable vector meet a preset error condition, and executing a subsequent iterative solution process based on the error determination result;

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

[0119] Reference Figure 4 , shows a structural block diagram of a numerical oscillation suppression device for electromechanical transient simulation of SVG provided by an embodiment of the present invention, which may specifically include:

[0120] A model building unit 401 is used to simultaneously consider the system state variables, system algebraic variables and node injection current of the power system during the transient simulation process to build an electromechanical transient simulation model of the power system;

[0121] A difference processing unit 402 is used to perform difference processing on the electromechanical transient simulation model to obtain an iterative equation at time n+1;

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

[0123] In an optional embodiment, the model building unit 401 includes:

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

[0125] A node voltage equation construction unit, used for acquiring a node admittance matrix of the power system, and constructing a node voltage equation 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 group, the second transient simulation equation group and the node voltage equation into an electromechanical transient simulation model of the power system.

[0127] In an optional embodiment, the differential processing unit 402 includes:

[0128] A difference processing subunit is used to obtain a preset first simulation step size, and based on the first simulation step size, use an implicit trapezoidal integration method to perform difference processing on the first transient simulation equation group and the second transient simulation equation group, respectively, to obtain a first difference equation group corresponding to the first transient simulation equation group, and a second difference equation group corresponding to the second transient simulation equation group;

[0129] A node voltage equation construction unit at time n+1, used to construct the node voltage equation at time n+1 of the node voltage equation;

[0130] The n+1 time iterative equation integration unit is used to integrate the first differential equation group, the second differential equation group and the n+1 time node voltage equation into the n+1 time iterative equation.

[0131] In an optional embodiment, the alternating iterative solution unit 403 includes:

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

[0133] A differential equation solving unit, used to execute step S02: when k≠0, combining linear interpolation and considering the simulation step size difference, solving the first system state variable vector and the first node injection current vector at the time n+1 by the first differential equation group, and solving the second system state variable vector and the second node injection current vector at the time n+1 by the second differential equation group;

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

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

[0136] In an optional embodiment, the differential equation solving unit includes:

[0137] a second simulation step length determining unit, configured to determine a second simulation step length according to the first simulation step length, wherein the second simulation step length is smaller than the first simulation step length, and the first simulation step length and the second simulation step length are in a positive integer proportional relationship;

[0138] A first differential 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 differential equation, and in the solving process, combine linear interpolation and use the second simulation step size for calculation;

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

[0140] In an optional embodiment, the first difference equation solving subunit includes:

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

[0142] A linear interpolation calculation unit is used to calculate, by linear interpolation, the intermediate values ​​of the system algebraic variable vector of each second simulation step of the SVG in the k-th iteration at time n+1, based on the system algebraic variable vector at time n, the system algebraic variable vector at time n+1, and the positive integer proportional relationship between the second simulation step and the first simulation step.

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

[0144] Determining whether the first system algebraic variable vector and the second system algebraic variable vector both meet a preset error requirement;

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

[0146] If not, continue to execute the k+1th alternating iterative solution process at time n+1 according to steps S02 to S04.

[0147] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the aforementioned method embodiment.

[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, some technical features are distinguished by the first and the second in the embodiments of the present invention. The first and the second are only used for data distinction and have no other special meanings. It can be understood that the present invention is not limited to this.

[0149] An embodiment of the present invention further provides an electronic device, the device comprising a processor and a memory:

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

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

[0152] An embodiment of the present invention further provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the numerical oscillation suppression method for electromechanical transient simulation of SVG according to any embodiment of the present invention.

[0153] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0154] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0155] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0156] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0157] If the integrated unit is implemented in the form of 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. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0158] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A numerical oscillation suppression method for electromechanical transient simulation of SVG, characterized in that: include: Simultaneously, the system state variables, system algebraic variables and node injection current of the power system during the transient simulation process are considered to construct an electromechanical transient simulation model of the power system; Performing a difference process on the electromechanical transient simulation model to obtain an iterative equation at time n+1; The n+1 time iterative equation is solved by alternating iteration combined with linear interpolation to obtain a transient simulation solution result of the power system.

2. The numerical oscillation suppression method according to claim 1, characterized in that: The method of simultaneously considering the system state variables, system algebraic variables and node injection current of the power system during the transient simulation process to construct an electromechanical transient simulation model of the power system includes: At the same time, considering the system state variables, system algebraic variables and node injection current of the power system during the transient simulation process, a first transient simulation equation group of the SVG is constructed in the form of a differential-algebraic equation group, and a second transient simulation equation group of the power equipment other than the SVG in the power system is constructed; Acquire a node admittance matrix of the power system, and construct a node voltage equation of the power system based on the node admittance matrix; The first transient simulation equation group, the second transient simulation equation group and the node voltage equation are integrated into an electromechanical transient simulation model of the power system.

3. The numerical oscillation suppression method according to claim 2, characterized in that: The electromechanical transient simulation model is subjected to a differential process to obtain an iterative equation at time n+1, including: Obtaining a preset first simulation step size, and based on the first simulation step size, using an implicit trapezoidal integration method to perform difference processing on the first transient simulation equation group and the second transient simulation equation group, respectively, to obtain a first difference equation group corresponding to the first transient simulation equation group, and a second difference equation group corresponding to the second transient simulation equation group; Constructing a node voltage equation at time n+1 of the node voltage equation; The first differential equation group, the second differential equation group 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 combined with linear interpolation includes: Step S01: when k=0, initializing the iterative initial value of the system algebraic variable vector in the node voltage equation at the time n+1; Step S02: when k≠0, combining linear interpolation and considering the simulation step size difference, solving the first system state variable vector and the first node injection current vector at time n+1 by the first differential equation group, and solving the second system state variable vector and the second node injection current vector at time n+1 by the second differential equation group; Step S03: Substitute the first system state variable vector and the first node injection current vector into the node voltage equation at the time n+1 to solve the first system algebraic variable vector at the time n+1, substitute the second system state variable vector and the second node injection current vector into the node voltage equation at the time n+1 to solve the second system algebraic variable vector at the time n+1; Step S04: determining whether the first system algebraic variable vector and the second system algebraic variable vector meet a preset error condition, and executing a subsequent iterative solution process based on the error determination result.

5. The numerical oscillation suppression method according to claim 4, characterized in that: The method combines linear interpolation and considers the simulation step size difference, solves the first system state variable vector and the first node injection current vector at time n+1 by using the first differential equation group, and solves the second system state variable vector and the second node injection current vector at time n+1 by using the second differential equation group, including: Determining a second simulation step length according to the first simulation step length, wherein the second simulation step length is smaller than the first simulation step length, and the first simulation step length and the second simulation step length are in a positive integer proportional relationship; For the SVG, solving the first system state variable vector and the first node injection current vector at time n+1 by using the first differential equation group, and in the solving process, combining linear interpolation and using the second simulation step size for calculation; For the power equipment other than the SVG in the power system, the first simulation step is adopted, and the second system state variable vector and the second node injection current vector at time n+1 are solved by the second differential equation group.

6. The numerical oscillation suppression method according to claim 5, characterized in that: In the solving process, combining linear interpolation and using the second simulation step size for calculation, the method includes: Obtaining a system algebraic variable vector of the SVG at time n and a system algebraic variable vector at time n+1; By adopting a linear interpolation method, based on the system algebraic variable vector at time n, the system algebraic variable vector at time n+1, and the positive integer proportional relationship between the second simulation step and the first simulation step, the intermediate values ​​of the system algebraic variable vector of each second simulation step of the SVG in the k-th iteration at time n+1 are calculated one by one.

7. The method for suppressing numerical oscillation according to any one of claims 4 to 6, characterized in that: The determining whether the first system algebraic variable vector and the second system algebraic variable vector meet a preset error condition, and executing a subsequent iterative solution process based on the error determination result, includes: Determining whether the first system algebraic variable vector and the second system algebraic variable vector both meet a preset error requirement; If yes, set k=0 and continue to perform the alternating iterative solution process at time n+2 according to steps S01 to S04; If not, continue to execute the k+1th alternating iterative solution process at time n+1 according to steps S02 to S04.

8. A numerical oscillation suppression device suitable for electromechanical transient simulation of SVG, characterized in that: include: A model building unit, used to simultaneously consider the system state variables, system algebraic variables and node injection current of the power system during the transient simulation process to build an electromechanical transient simulation model of the power system; A differential processing unit, used for performing differential processing on the electromechanical transient simulation model to obtain an iterative equation at time n+1; The alternating iterative solution unit is used to perform alternating iterative solution combined with linear interpolation on the n+1 time iterative equation to obtain a transient simulation solution result of the power system.

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

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and the program codes are used to execute the numerical oscillation suppression method for electromechanical transient simulation applicable to SVG according to any one of claims 1 to 7.

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