A simulation method and related devices for a power system

Abstract

This invention discloses a simulation method and related apparatus for a power system. The method includes: dividing the main power grid of the power system into sub-networks, dividing the sub-networks into converter subsystems, and dividing the converter subsystems into switching sub-circuits; simulating the sub-networks and converter subsystems using a large-step simulation method, simulating the switching sub-circuits within the critical window of switching action using a small-step simulation method, and simulating the switching sub-circuits in other time periods using a large-step simulation method; wherein the large step size is an integer multiple of the small step size; the critical window of switching action is determined based on the simulation results of the switching sub-circuits of the current simulation time step and the historical simulation time steps, and the small step size is determined based on the step-coupling stability judgment of the switching sub-circuits within the critical window of switching action. This invention separates the transient process of switching from the slow dynamic process of the main power grid through three-level topology decoupling. It uses small-step fine-grained solution for local switching subcircuits only within a very short window before and after the switching action, while using large-step solution for the entire system in the remaining time domain. This eliminates the computational redundancy caused by small-step solution for the entire system, effectively compressing computational overhead and reducing simulation resource consumption. Furthermore, this invention uses a hybrid simulation strategy to balance the numerical stability of slow dynamic processes with the solution efficiency of fast dynamic processes. It can ensure the simulation efficiency of electromagnetic transients with a high proportion of power electronics connected to the power system while maintaining the accuracy of switching transient simulation and long-term time domain numerical stability.

Description

Technical Field

[0001] This invention relates to a simulation method and related apparatus for power systems, belonging to the field of electromagnetic transient simulation technology for power systems. Background Technology

[0002] New power systems with a high proportion of power electronic devices (new energy generation, flexible DC devices, power electronic loads, etc.) exhibit multi-timescale characteristics with a high degree of coupling between slow dynamics at power frequency and fast dynamics at the microsecond level of power electronics, posing stringent requirements on both the accuracy and efficiency of electromagnetic transient simulation. Due to the complex structure, high model order, and large number of power electronic devices in these new power systems, traditional electromagnetic transient simulation methods are severely limited in both speed and accuracy. Summary of the Invention

[0003] This invention provides a power system simulation method and related apparatus, which solves the problems disclosed in the background art.

[0004] According to one aspect of this application, a simulation method for a power system is provided, comprising:

[0005] The main power grid of the power system is divided into sub-networks, the sub-networks are divided into converter subsystems, and the converter subsystems are divided into switching sub-circuits.

[0006] A large-step simulation method is used to simulate the sub-network and converter subsystem. A small-step simulation method is used to simulate the switching sub-circuit within the critical window of switching action. A large-step simulation method is used to simulate the switching sub-circuit in other time periods. The large step size is an integer multiple of the small step size. The critical window of switching action is determined based on the simulation results of the switching sub-circuit in the current simulation time step and the historical simulation time steps. The small step size is determined based on the step-coupling stability judgment of the switching sub-circuit within the critical window of switching action.

[0007] Furthermore, the main power grid of the power system is divided into sub-networks, each sub-network is further divided into converter subsystems, and each converter subsystem is further divided into switching sub-circuits, including:

[0008] Using the Beryllon transmission line model, the wave propagation delay is no less than 2t. b The transmission lines are discretized and decoupled, with each segment serving as a boundary condition for a different sub-network, thus dividing the main power grid into multiple independent sub-networks; where t b For large stride length;

[0009] Within each sub-network, each power electronic conversion device is divided into an independent converter subsystem;

[0010] Within each converter subsystem, switching devices without direct electrical coupling, along with their associated buffer circuits and filter branches, are divided into independent switching sub-circuits, while electrically coupled multi-bridge arm switches are merged into a single switching sub-circuit.

[0011] Furthermore, prior to simulation, the process includes using the Thevenin equivalent model to equivalence the converter subsystem, using the Norton equivalent model to equivalence the switching sub-circuit, and performing simulation based on the equivalent models.

[0012] Furthermore, the critical window for switching action is determined based on the simulation results of the switching sub-circuit at historical simulation time steps, including:

[0013] Based on the simulation results of the switching sub-circuit at the current simulation time step and the historical simulation time step, calculate the cumulative value of the simulation error of the switching sub-circuit and the critical moment of switching action;

[0014] If the critical moment for the switch action is located in the future 2t b The cumulative simulation error of the internal or switching sub-circuit exceeds the theoretical value, which will affect the future 2t b As the critical window for switching action; where t b For large stride length.

[0015] Furthermore, the formula for calculating the critical moment of the switching action is as follows:

[0016] ;

[0017] In the formula, t sw Let t be the critical moment for the switch action, and t be the current time. u(tt) b u(t) and u(t) are the terminal voltages of the switching devices in the simulation results of the switching sub-circuit in the previous simulation time step and the current simulation time step, respectively.

[0018] Furthermore, the small step size is determined based on the step-coupling stability of the switching sub-circuit within the critical window of the switching action, including:

[0019] 1) Construct an augmented state-space model that includes the switching sub-circuit and the connected converter subsystem;

[0020] 2) Discretize the augmented state space model according to the initial small step size to obtain the single-step state transition matrix. Based on the single-step state transition matrix and the multiple relationship between the large step size and the initial small step size, calculate the periodic equivalent state transition matrix.

[0021] 3) If the maximum value of the modulus of the eigenvalues ​​of the periodic equivalent state transition matrix is ​​less than or equal to the first threshold, then the initial small step size is used as the small step size for simulation.

[0022] If the maximum value of the modulus of the eigenvalues ​​of the periodic equivalent state transition matrix is ​​greater than the first threshold and less than or equal to the second threshold, then the initial small step size is reduced to half of the original size, and the reduced small step size is used as the new initial small step size, and then proceeds to step 2).

[0023] Furthermore, during the small-step simulation, the first voltage and second voltage of the common node, as well as the first current and second current of the common node at the same moment, are compared. If both the voltage error and the current error exceed the third threshold, the small-step simulation results are used to recalculate and correct the circuits surrounding the common node connected to the switching sub-circuit in the converter subsystem until both the voltage error and the current error do not exceed the third threshold. Here, the common node is the connection point between the converter subsystem and the switching sub-circuit. The first voltage and first current of the common node are obtained from the large-step simulation, and the second voltage and second current of the common node are obtained from the small-step simulation.

[0024] According to another aspect of this application, a power system simulation device is provided, characterized in that it comprises:

[0025] The module is divided into sub-networks for the main power grid of the power system, converter subsystems for the sub-networks, and switching sub-circuits for the converter subsystems.

[0026] The simulation module employs a large-step simulation method to simulate the sub-network and converter subsystem, a small-step simulation method to simulate the switching sub-circuits within the critical window of switching action, and a large-step simulation method to simulate the switching sub-circuits in other time periods. The large step size is an integer multiple of the small step size. The critical window of switching action is determined based on the simulation results of the switching sub-circuits at the current simulation time step and historical simulation time steps, while the small step size is determined based on the step-coupling stability judgment of the switching sub-circuits within the critical window of switching action.

[0027] According to another aspect of this application, a computer-readable storage medium is provided that stores one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a simulation method for a power system.

[0028] According to another aspect of this application, a computer device is provided, including one or more processors and one or more memories, wherein one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing a simulation method for a power system.

[0029] The beneficial effects achieved by this invention are as follows: This invention separates the transient process of switching from the slow dynamic process of the main power grid through three-level topology decoupling. It only uses small-step fine-grained solution for local switching sub-circuits within a very short window before and after the switching action, while using large-step solution for the rest of the time domain system. This eliminates the computational redundancy caused by small-step solution for the whole system, effectively compressing computational overhead and reducing simulation resource consumption. Furthermore, this invention, through a hybrid simulation strategy, balances the numerical stability of slow dynamic processes with the solution efficiency of fast dynamic processes. It can ensure the simulation efficiency of electromagnetic transients with a high proportion of power electronics connected to the power system while ensuring the accuracy of switching transient simulation and long-term time domain numerical stability. Attached Figure Description

[0030] Figure 1 A flowchart of a power system simulation method;

[0031] Figure 2 This is a block diagram of a power system simulation device. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0033] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0034] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0035] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0036] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0037] It should be noted that similar symbols and letters in the accompanying drawings represent similar items; therefore, once an item is defined in one accompanying drawing, it does not need to be discussed further in subsequent accompanying drawings.

[0038] Furthermore, in the description of the embodiments of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features.

[0039] This application provides a power system simulation method. The simulation can be executed by a simulation device, which can be a terminal device or a server. The terminal device can include, but is not limited to, mobile phones, computers, etc. The server can be a standalone physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, big data, and artificial intelligence platforms. Optionally, the simulation method can also be executed collaboratively by multiple electronic devices with computing power. For ease of explanation, subsequent embodiments will be described as being executed by a simulation device.

[0040] See Figure 1 , Figure 1 This is a flowchart of a power system simulation method provided in an embodiment of this application. The simulation method can be executed by a simulation device and may include at least the following steps:

[0041] Step 1: Divide the main power grid of the power system into sub-networks, divide the sub-networks into converter subsystems, and divide the converter subsystems into switching sub-circuits.

[0042] It should be noted that, similar to traditional simulation, in order to reduce the amount of simulation computation, the power system to be simulated needs to be divided and decoupled. That is, the power system to be simulated is divided into a three-level architecture of sub-network, converter subsystem and switching sub-circuit according to electrical coupling degree and dynamic time scale, and then boundary decoupling is performed.

[0043] In some embodiments, the Berylon transmission line model can be used, with a wave propagation delay of not less than 2t. b The transmission lines are discretized and decoupled, with each segment serving as a boundary condition for a different sub-network, thus dividing the main power grid into multiple independent sub-networks; where t b For large stride length.

[0044] It should be noted that the inherent time delay decoupling characteristics of the Berylon transmission line model are used for transmission line discretization and decoupling.

[0045] Changes in electrical quantities at one end of a transmission line require a wave propagation delay τ to reach the other end. Therefore, within a single simulation step, the electrical quantities at both ends are not directly coupled. The power grid at both ends of the transmission line can be split into two independent sub-networks to achieve parallel solution.

[0046] For single-phase lossy transmission lines, the Beryllon equivalent equation is obtained by discretization using the implicit trapezoidal integral method. The specific formula is as follows:

[0047] ;

[0048] In the formula, u k (t1) and u m (t1) represents the voltage at the two nodes (defined as k-terminal and m-terminal) of the transmission line at time t1, i k (t1) and i m (t1) represents the branch current flowing from end k to end m of the transmission line at time t1, and the branch current flowing from end m to end k of the transmission line, respectively. For transmission line impedance, Let L be the wave propagation delay, and C be the inductance and capacitance per unit length, respectively. Let l be the transmission line length, and i be the propagation delay. k (t1-τ) and i m (t1-τ) represents the historical current source terms, specifically the branch current flowing from end k to end m of the transmission line at time t1-τ and the branch current flowing from end m to end k of the transmission line.

[0049] Screening τ≥2t b The transmission line serves as the decoupling boundary line, splitting the main power grid into multiple sub-networks for load balancing calculations. Each sub-network solves independently, achieving natural decoupling.

[0050] Within each sub-network, each power electronic conversion device is divided into an independent converter subsystem. The converter subsystem is connected to the main grid only through a common node (PCC), and there are no internal branches across subsystems, ensuring the electrical independence of the subsystem.

[0051] Within each converter subsystem, switching devices without direct electrical coupling, along with their associated buffer circuits and filter branches, are divided into independent switching sub-circuits. Electrically coupled multi-bridge arm switches are merged into a single switching sub-circuit to ensure that the switching transient process is completely enclosed within the sub-circuit. The switching sub-circuit is connected to the converter subsystem only through 1 to 2 common nodes.

[0052] It should be noted that port decoupling between the switching sub-circuit and the converter subsystem can be achieved based on the Thevenin equivalent model and the Norton equivalent model, thus constructing an equivalent circuit model. Specifically, the Norton equivalent model can be used to perform equivalence on the switching sub-circuit, as follows:

[0053] Dividing the nodes of the switching sub-circuit into internal nodes and common nodes, establishing the block node voltage equations, and obtaining the Norton equivalent model of the switching sub-circuit through Gaussian elimination, it can be expressed as:

[0054] ;

[0055] In the formula, U pcc and I pcc The equivalent admittance is given by the voltage and injected current at the common node (i.e., the common node connecting the switching sub-circuit and the converter subsystem). Y ii Y pp Y ip and Y pi For block admittance matrix, energy efficiency current source I i Inject current sources into internal nodes.

[0056] The Thevenin equivalent model can be used to perform equivalent transformation on the converter subsystem. The specific Thevenin equivalent model can be expressed as follows:

[0057] ;

[0058] In the formula, the equivalent voltage source equivalent impedance Y pp Y pm Y mm and Y mp This is the block admittance matrix.

[0059] In the above division process, the main power grid is decoupled based on the Berylon transmission line, and the switching sub-circuit is decoupled based on the Norton-Thevenin port. Each level of subsystem can be solved independently, which is naturally adapted to distributed parallel computing and heterogeneous acceleration, greatly improving simulation efficiency. Furthermore, the switching transient process can be completely enclosed in the independent switching sub-circuit, realizing fine-grained solution of only the local small step size of the switching sub-circuit, avoiding the computational redundancy caused by the step size switching of the whole system.

[0060] Step 2: Employ a large-step simulation method to simulate the sub-network and converter subsystem; employ a small-step simulation method to simulate the switching sub-circuits within the critical window of switching action; and use a large-step simulation method to simulate the switching sub-circuits in other time periods. The large step size is an integer multiple of the small step size to satisfy time synchronization constraints. The critical window of switching action is determined based on the simulation results of the switching sub-circuits at the current simulation time step and historical simulation time steps. The small step size is determined based on the step-coupling stability of the switching sub-circuits within the critical window of switching action.

[0061] It should be noted that the range of the large step size can be 50μs to 200μs, adapting to the dynamic characteristics of the power frequency grid. The large step size simulation method can adopt the implicit trapezoidal integration method, specifically: for resistor R... R Inductor L L Capacitor C CThe component is discretized into an adjoint model of equivalent conductance plus historical current source using the implicit trapezoidal integral method; whereby the equivalent conductance of the inductor can be expressed as G. L =t b / 2L L The corresponding historical current source can be represented as I. L =i L (tt b )+G L *u L (tt b ), i L (tt b ) and u L (tt b These represent the inductor node current and voltage of the previous large step size, respectively; the equivalent conductance of the capacitor element can be expressed as G. C =2C C / t b The corresponding historical current source can be represented as I. C =-i C (tt b )-G C *u C (tt b ), i C (tt b ) and u C (tt b ) are the current and voltage of the capacitor node in the previous large step, respectively; the resistor element has no historical term after discretization, and the equivalent conductance is the reciprocal of the resistance.

[0062] The subnetworks and converter subsystems can be simulated in parallel with large steps. Specifically, each subnetwork can be assigned to an independent computing core, i.e., each computing core corresponds to one subnetwork. Based on the adjoint model, the node admittance matrix Y of the subnetwork is assembled, and the dimension of the node admittance matrix Y is the number of internal nodes of the subnetwork × the number of internal nodes. The injected current sources of all nodes in the subnetwork are summarized to construct the node injected current column vector. The node voltage equations of the subnetwork are established to obtain the voltages of all internal nodes of the subnetwork. The common node voltages of the converter subsystem and the switching subcircuit are extracted from the solution results and sent to the corresponding switching subcircuit as boundary conditions to complete the large-step basic solution.

[0063] For switching sub-circuits without switch action prediction and marked as steady state, simulations can be performed with large step sizes synchronized with the main circuit (i.e., sub-network and converter subsystem). This updates the device state variables and equivalent Norton parameters, synchronizing them to the converter subsystem, minimizing invalid calculations, and improving simulation efficiency.

[0064] In some embodiments, the cumulative value of the switching sub-circuit simulation error and the critical moment of switching action can be calculated based on the simulation results of the switching sub-circuit at the current simulation time step and the historical simulation time steps; if the critical moment of switching action is located in the future 2t... b The cumulative simulation error of the internal or switching sub-circuit exceeds the theoretical value, which will affect the future 2t b As a critical window for switching actions.

[0065] It should be noted that the switching function s of the switching device can be defined, where s=1 when on and s=0 when off, based on tt. b The critical moment for switching action can be calculated by linear interpolation using the terminal voltage of the switching device at time t, and the formula can be expressed as:

[0066] ;

[0067] In the formula, t sw Let t be the critical moment for the switch action, and t be the current time. u(tt) b ) and u(t) are the terminal voltages of the switching devices in the simulation results of the switching sub-circuit in the previous simulation time step and the current simulation time step, respectively, i.e., tt b And the voltage at the terminal of the switching device at time t. If t sw If the circuit falls within the time window [t, t+2tb], then the switch sub-circuit is marked as a state to be refined and the time window [t, t+2tb] is locked.

[0068] For the marked switching sub-circuit, a small-step simulation method is used to simulate the switching sub-circuit when the locking time window is reached. It should be noted that, while performing the small-step simulation, a large-step simulation is also performed simultaneously on the sub-network and converter subsystem.

[0069] Different switching sub-circuits have large differences in time constants and switching frequencies, and a fixed small step size cannot adapt to all scenarios, easily leading to numerical oscillations. Therefore, in some embodiments, the small step size can be determined based on the step size coupling stability of the switching sub-circuit within the critical window of switching action. The specific process may include:

[0070] 1) Construct an augmented state-space model that includes the switching sub-circuit and the connected converter subsystem.

[0071] Augmented state-space model It can be represented as:

[0072] ;

[0073] ;

[0074] ;

[0075] In the formula, xf x is the fast dynamic state vector of the switching sub-circuit. s Let X be the slow dynamic state vector of the converter subsystem, X be the augmented state vector, and A be the state coefficient matrix, which fully characterizes the coupling dynamics of the switching subcircuit and the converter subsystem. f and A s These are the state coefficient matrices for the switching sub-circuit and the converter subsystem, respectively. f and B s C represents the input coefficient matrices of the switching subcircuit and the converter subsystem, respectively, characterizing the input effects of the common node voltage on the switching subcircuit and the input effects of the common node current on the converter subsystem. f and C s These are the output coefficient matrices for the switching sub-circuit and the converter subsystem, respectively, representing the mapping relationship of the switching sub-circuit to the common node current and the mapping relationship of the converter subsystem to the common node voltage.

[0076] 2) Discretize the augmented state space model according to the initial small step size to obtain the single-step state transition matrix. Based on the single-step state transition matrix and the multiple relationship between the large step size and the initial small step size, calculate the periodic equivalent state transition matrix.

[0077] It should be noted that the initial small step size t small It can be set to less than 1 / (20f), where f is the switching frequency of the switching device, ensuring the Nyquist sampling theorem requirements. According to t small Discretization yields the single-step state transition matrix. Calculate the periodic equivalent state transition matrix G N =σ N N=t b / t small .

[0078] 3) If the maximum value of the modulus of the eigenvalues ​​of the periodic equivalent state transition matrix is ​​less than or equal to the first threshold, then the initial small step size is used as the small step size of the simulation; if the maximum value of the modulus of the eigenvalues ​​of the periodic equivalent state transition matrix is ​​greater than the first threshold and less than or equal to the second threshold, then the initial small step size is reduced to 1 / 2 of the original size, and the reduced small step size is used as the new initial small step size, and then proceed to 2); where the first threshold is generally set to 0.99, and the second threshold is generally set to 1.

[0079] It should be noted that the modulus of the eigenvalues ​​of the periodic equivalent state transition matrix can be expressed as |λ i (G N If max|λ i (G N If |≤0.99, then the step size coupling is considered stable, and the simulation is performed according to the initial small step size; if 0.99 <max|λ i (GN If | ≤ 1, then reduce the initial small step size to half of the original size and recalculate G. N Continue until the step-size coupling stabilizes to avoid numerical oscillations and divergences in the simulation; if max|λ i (G N If |>1, then the step size coupling is determined to be unstable, and step size switching is prohibited, that is, switching to small step size simulation is prohibited, and large step size simulation is triggered, that is, large step size simulation is also used within the critical window of switching action.

[0080] The above achieves dynamic adjustment of small step size, which can ensure that the multi-step coupled system is always in the stable region. Furthermore, it can use the largest possible small step size while meeting the requirements of stability and accuracy, thereby reducing the number of small step size iterations and further compressing computational overhead.

[0081] It should be noted that the small-step simulation method can employ a fourth-order explicit integration method, as specifically implemented below:

[0082] First-order differential state equations for switching sub-circuits , Let x be the state vector f The first derivative, Let x be the state vector f The nonlinear function at time t fully characterizes the dynamic characteristics of the switching sub-circuit (derived from the volt-ampere characteristics of inductors, capacitors, and switching devices). The state vector is updated using a fourth-order explicit integral formula for each small step within the critical window of switching action.

[0083] ;

[0084] In the formula, x f,n and x f,n+1 These are the state vectors corresponding to the nth and (n+1)th small steps, respectively, f n ~f n-3 Based on the differential function values ​​of the first four time points and the updated state vector, the node voltage and branch current inside the switching sub-circuit are calculated, the on / off state of the switching device is updated in real time, the actual time of switching action and the end time of the critical window of switching action are accurately captured, the Norton equivalent parameters of the switching sub-circuit and the device state variables are calculated, and the results are output to the main circuit.

[0085] Since small-step simulations and large-step simulations are not executed during the critical window of switching action, in order to eliminate the cumulative error caused by multi-step coupling and ensure global data consistency, in some embodiments, during the small-step simulation, the first voltage and second voltage of the common node, as well as the first current and second current of the common node at the same moment, are compared. If both the voltage error and the current error exceed a third threshold, the small-step simulation results are used to recalculate and correct the circuits surrounding the common node connected to the switching sub-circuit in the converter subsystem until both the voltage error and the current error do not exceed the third threshold. Here, the common node is the connection point between the converter subsystem and the switching sub-circuit; the first voltage and first current of the common node are obtained from the large-step simulation, and the second voltage and second current of the common node are obtained from the small-step simulation. The third threshold is generally set to 10. -6 .

[0086] Voltage error and current error can be expressed as:

[0087] ;

[0088] ;

[0089] In the formula, η U and η I These are voltage error and store error, respectively, U pcc,small and U pcc,b The common node voltage was obtained through small-step simulation and large-step simulation, respectively. pcc,small and I pcc,b The common node current is obtained through small-step and large-step simulations, respectively. If η U and η I All exceeded 10 -6 The converter subsystem is locally recalculated using port equivalent parameters obtained by small step size calculations until the error does not exceed 10. -6 This eliminates the cumulative error of multi-step operations.

[0090] After calibration, the state variables of the switching sub-circuit are synchronized to the global model (i.e., the complete power system simulation model that includes all main grid sub-networks, converter subsystems, and switching sub-circuits) to ensure that the states of all subsystems (subsystems refer to all main grid-level sub-networks, converter subsystems, and switching sub-circuits involved in this simulation) are completely consistent at the end time, eliminating accumulated errors. After the critical window of switching action is solved, the switching sub-circuit is switched back to large step simulation, the state flags to be refined are cleared, and the switching action prediction and stability verification parameters are reset.

[0091] The above method can construct a causal dependency graph of all subsystems, determine the simulation progress order based on topological sorting, and perform high-order Lagrange interpolation on subsystem data with different time steps during simulation to achieve full system time synchronization. After the current simulation time step is completed, the simulation time step is entered again until the preset total simulation time is reached, and then the simulation results are exported.

[0092] The above method can ensure the efficiency of electromagnetic transient simulation with a high proportion of power electronics connected to the power system, while maintaining the accuracy of switching transient simulation and long-term time-domain numerical stability. It effectively reduces computational overhead, decreases simulation resource consumption, and significantly improves the practicality of real-time power system simulation.

[0093] The above method separates the transient process of switching from the slow dynamic process of the main power grid through three-level topology decoupling. It only uses small-step fine-grained solution for local switching sub-circuits within a very short window before and after the switching action, while using large-step solution for the entire system in the remaining time domain. This eliminates the computational redundancy caused by small-step solution for the entire system, effectively compressing computational overhead and reducing simulation resource consumption. Furthermore, the above method uses a hybrid simulation strategy to balance the numerical stability of slow dynamic processes with the solution efficiency of fast dynamic processes. It can ensure the simulation efficiency of electromagnetic transients with a high proportion of power electronics connected to the power system while guaranteeing the accuracy of switching transient simulation and long-term time domain numerical stability.

[0094] The above method also fundamentally avoids the numerical oscillation and divergence problems of multi-step simulation by real-time verification of step-length coupling stability and step-length closed-loop adjustment. Through interface closed-loop correction and global time synchronization mechanism, it ensures the accuracy and data consistency of multi-scale simulation.

[0095] See Figure 2 , Figure 2 This is a block diagram of a power system simulation device provided in an embodiment of this application. The device is a virtual device that can be loaded and executed by a computer device, which may include the aforementioned simulation device. Figure 2 The apparatus may include a partitioning module and a simulation module, which, when used to execute the above simulation method, can:

[0096] The module is divided into sub-networks for the main power grid of the power system, and then into converter subsystems for each sub-network, and finally into switching sub-circuits for each converter subsystem.

[0097] The simulation module employs a large-step simulation method to simulate the sub-network and converter subsystem, a small-step simulation method to simulate the switching sub-circuits within the critical window of switching action, and a large-step simulation method to simulate the switching sub-circuits in other time periods. The large step size is an integer multiple of the small step size. The critical window of switching action is determined based on the simulation results of the switching sub-circuits at the current simulation time step and historical simulation time steps, while the small step size is determined based on the step-coupling stability judgment of the switching sub-circuits within the critical window of switching action.

[0098] It should be noted that, in some embodiments, the simulation device may be configured with a CPU solving unit and an FPGA solving unit. The simulation module may include a large-step simulation module and a small-step simulation module, wherein the large-step simulation module is loaded in the CPU solving unit, and the small-step simulation module is loaded in the FPGA solving unit. While the CPU solving unit performs large-step simulation, the FPGA solving unit performs small-step simulation in parallel. The computation time of the CPU solving unit can be used to mask the communication time between the two, maximizing the heterogeneous speedup ratio.

[0099] The aforementioned device separates the transient switching process from the slow dynamic process of the main power grid through three-level topology decoupling. It only uses small-step fine-grained solution for local switching sub-circuits within a very short window before and after the switching action, while using large-step solution for the entire system in the remaining time domain. This eliminates the computational redundancy caused by small-step solution for the entire system, effectively compressing computational overhead and reducing simulation resource consumption. Furthermore, the device uses a hybrid simulation strategy to balance the numerical stability of the slow dynamic process with the solution efficiency of the fast dynamic process. It can ensure the electromagnetic transient simulation efficiency of a high proportion of power electronics connected to the power system while guaranteeing the accuracy of the switching transient simulation and the long-term numerical stability.

[0100] This application also relates to a computer-readable storage medium that stores one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a simulation method for a power system.

[0101] This application also relates to a computer device including one or more processors and one or more memories, wherein one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing a simulation method for a power system.

[0102] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0103] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0104] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0105] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0106] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A simulation method for a power system, characterized in that, include: The main power grid of the power system is divided into sub-networks, the sub-networks are divided into converter subsystems, and the converter subsystems are divided into switching sub-circuits. A large-step simulation method is used to simulate the sub-network and converter subsystem; a small-step simulation method is used to simulate the switching sub-circuit within the critical window of switching action; and a large-step simulation method is used to simulate the switching sub-circuit in other time periods. The large step size is an integer multiple of the small step size. The critical window for switching action is determined based on the simulation results of the switching sub-circuit at the current simulation time step and the historical simulation time steps, while the small step size is determined based on the step size coupling stability of the switching sub-circuit within the critical window for switching action.

2. The method according to claim 1, characterized in that, The main power grid of the power system is divided into sub-networks, each sub-network is further divided into converter subsystems, and each converter subsystem is further divided into switching sub-circuits, including: Using the Beryllon transmission line model, the wave propagation delay is no less than 2t. b The transmission lines are discretized and decoupled, with each segment serving as a boundary condition for a different sub-network, thus dividing the main power grid into multiple independent sub-networks; where t b For large stride length; Within each sub-network, each power electronic conversion device is divided into an independent converter subsystem; Within each converter subsystem, switching devices without direct electrical coupling, along with their associated buffer circuits and filter branches, are divided into independent switching sub-circuits, while electrically coupled multi-bridge arm switches are merged into a single switching sub-circuit.

3. The method according to claim 1, characterized in that, Before simulation, the process includes using the Thevenin equivalent model to equivalence the converter subsystem, using the Norton equivalent model to equivalence the switching sub-circuit, and performing simulation based on the equivalent models.

4. The method according to claim 1, characterized in that, The critical window for switching action is determined based on the simulation results of the switching sub-circuit at historical simulation time steps, including: Based on the simulation results of the switching sub-circuit at the current simulation time step and the historical simulation time step, calculate the cumulative value of the simulation error of the switching sub-circuit and the critical moment of switching action; If the critical moment for the switch action is located in the future 2t b The cumulative simulation error of the internal or switching sub-circuit exceeds the theoretical value, which will affect the future 2t b As the critical window for switching action; where t b For large stride length.

5. The method according to claim 4, characterized in that, The formula for calculating the critical moment of switch action is: ； In the formula, t sw Let t be the critical moment for the switch action, and t be the current time. u(tt) b u(t) and u(t) are the terminal voltages of the switching devices in the simulation results of the switching sub-circuit in the previous simulation time step and the current simulation time step, respectively.

6. The method according to claim 1, characterized in that, The small step size is determined based on the step size coupling stability of the switching sub-circuit within the critical window of the switching action, including: 1) Construct an augmented state-space model that includes the switching sub-circuit and the connected converter subsystem; 2) Discretize the augmented state space model according to the initial small step size to obtain the single-step state transition matrix. Based on the single-step state transition matrix and the multiple relationship between the large step size and the initial small step size, calculate the periodic equivalent state transition matrix. 3) If the maximum value of the modulus of the eigenvalues ​​of the periodic equivalent state transition matrix is ​​less than or equal to the first threshold, then the initial small step size is used as the small step size for simulation. If the maximum value of the modulus of the eigenvalues ​​of the periodic equivalent state transition matrix is ​​greater than the first threshold and less than or equal to the second threshold, then the initial small step size is reduced to half of the original size, and the reduced small step size is used as the new initial small step size, and then proceeds to step 2).

7. The method according to claim 1, characterized in that, During the small-step simulation, the first voltage and second voltage of the common node, as well as the first current and second current of the common node at the same moment, are compared. If both the voltage error and the current error exceed the third threshold, the small-step simulation results are used to recalculate and correct the circuits surrounding the common node connected to the switching sub-circuit in the converter subsystem until both the voltage error and the current error do not exceed the third threshold. Here, the common node is the connection point between the converter subsystem and the switching sub-circuit. The first voltage and first current of the common node are obtained from the large-step simulation, and the second voltage and second current of the common node are obtained from the small-step simulation.

8. A power system simulation device, characterized in that, include: The module is divided into sub-networks for the main power grid of the power system, converter subsystems for the sub-networks, and switching sub-circuits for the converter subsystems. The simulation module employs a large-step simulation method to simulate the sub-network and converter subsystem, a small-step simulation method to simulate the switching sub-circuit within the critical window of switching action, and a large-step simulation method to simulate the switching sub-circuit in other time periods; wherein the large step size is an integer multiple of the small step size. The critical window for switching action is determined based on the simulation results of the switching sub-circuit at the current simulation time step and the historical simulation time steps, while the small step size is determined based on the step size coupling stability of the switching sub-circuit within the critical window for switching action.

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

10. A computer device, characterized in that, include: One or more processors and one or more memories, one or more programs stored in one or more memories and configured to be executed by one or more processors, the one or more programs including instructions for performing the method of any one of claims 1 to 7.

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