Electromechanical transient simulation model library, simulation method and device for conventional direct current

Abstract

The invention provides an electromechanical transient simulation model library, a simulation method and a device for conventional direct current, the model library comprises a primary model library and a secondary model library which are established based on a universal modeling thought, specifically, the primary model library is composed of element models generated by modeling high-voltage circuit elements, and the secondary model library is composed of element models generated by modeling high-voltage circuit elements. And the secondary model library is composed of module models generated by modeling the operation control module. According to the method, an electromechanical transient simulation model library is constructed based on the thought of universal modeling, model parameters of a direct-current control system are determined by adopting a modeling method based on classified equivalent centralized compensation, simulation is performed by adopting a multi-rate alternate iteration method, a direct-current circuit is solved based on a historical current source method, and the simulation accuracy is improved. And an integral switching method is adopted to consider calculation precision and stability, so that a user can construct a new direct current model through simple operation, and full coordination of precision, speed and stability of electromechanical transient simulation is realized through simulation calculation.

Description

Technical Field

[0001] The present invention relates to the field of electric power simulation, and more specifically, to an electromechanical transient simulation model library, a simulation method and a device for conventional direct current. Background Art

[0002] DC transmission has the advantages of large transmission capacity, high economic benefits, and asynchronous interconnection, making it the main form of cross-regional long-distance power transmission. These DCs have different topological structures, including simple two-terminal networks, layered transmission and receiving ends, short-line connections between high and low ends, and parallel connection of converter valves at the transmission and receiving ends; they have two different control technology routes: limiting type and selective type; and their characteristics are complex and changeable. In addition, the power grid presents the prominent characteristics of "strong DC and weak AC", and the electrical coupling and interaction between AC and DC, and between the transmission and receiving ends are constantly intensifying. Local faults are transmitted through the DC system and transformed into shocks to the entire network, seriously threatening the safe and stable operation of the power grid.

[0003] The main technical means for power grid safety and stability analysis are electromechanical transient simulation and electromagnetic transient simulation. DC electromagnetic transient simulation has high accuracy but slow calculation speed and limited simulation scale; DC electromechanical transient simulation can better balance the contradiction between calculation speed and simulation accuracy. Compared with electromagnetic transient, the calculation efficiency is dozens of times higher, which is suitable for large-scale power grid simulation. It is an important simulation technology for power grid planning, design, construction, operation, scientific research and teaching. At present, more than 90% of power grid safety and stability analysis uses electromechanical transient simulation.

[0004] The existing conventional DC electromechanical transient model originated in the 1990s. With the continuous development of DC construction, although it can meet the simulation needs of simple topology DC, it has poor versatility and is not convenient for in-depth research on DC characteristics; it is not suitable for complex topology DC simulation; and it fails to coordinate calculation stability, accuracy and efficiency. Specifically, ① The current DC model is developed separately according to the limiting and selective control technology routes and topological characteristics such as whether it is layered. The ability to be compatible with new control methods and topological structures is poor, and it cannot support researchers and planners to construct new DC with existing software. For new DC, it is often necessary to build a special model or patch the old model, making the simulation tool always lag behind the actual engineering needs. ② In the existing DC project, there is an additional DC line between the high and low ends of the sending end, and the DC after the transformation adopts a parallel structure of converter valves, which the existing models cannot adapt to. ③ There are many DC control links, each link has a certain number of function boxes and parameters, and the overall details are very many. How to establish a DC control model with high precision while ensuring a faster calculation speed is a major problem. At present, the commonly used method is to fit each link, that is, to design a special test for each control link, adjust the parameters of the link under the test, and complete the fitting of all parameters link by link. ④ The current model does not consider measures to suppress numerical oscillations after large disturbances. Summary of the invention

[0005] In order to solve the technical problems in the prior art of insufficient versatility of the electromechanical transient simulation model construction process, unsuitability for complex topological structures, and insufficient coordination between accuracy, speed and stability, the present invention provides an electromechanical transient simulation model library, simulation method and device for conventional direct current.

[0006] According to one aspect of the present invention, the present invention provides a model library for electromechanical transient simulation of conventional direct current, the model library comprising a primary model library and a secondary model library established based on a generalized modeling idea, wherein:

[0007] The primary model library is composed of component models generated by modeling high-voltage circuit components, wherein the high-voltage circuit components are generated by decomposing the primary part of an existing conventional DC project;

[0008] The secondary model library is composed of module models generated by modeling the operation control module, wherein the operation control module is generated by decomposing the secondary part of an existing conventional direct current project.

[0009] Optionally, the primary model library includes an AC sub-model library for AC side equivalent circuit simulation and a DC sub-model library for DC side equivalent circuit simulation, wherein:

[0010] The AC sub-model library includes models established for converter transformers and parallel compensation devices;

[0011] The DC sub-model library includes models established for a DC converter, a DC line, a smoothing reactor, a DC connecting line, a fault grounding branch, a DC filter and an equivalent diode.

[0012] Optionally, the model of the converter transformer established in the AC side sub-model library only includes the ideal transformation ratio, and the transformer body loss impedance is realized by establishing an impedance model in the DC sub-model library.

[0013] Optionally, the DC converter uses a quasi-steady-state formula to describe its model, wherein the formula of the inverter-side converter is as follows:

[0014] DC no-load open circuit voltage V d0 The expression is:

[0015]

[0016] Commutation voltage drop ΔV dc The expression is:

[0017]

[0018] DC line voltage V dc The expression is:

[0019] V dc =V d0 cosβ+ΔV dc

[0020] The expression of the commutation angle μ is:

[0021]

[0022] The expression of the cut-off angle γ is:

[0023] γ=β-μ

[0024] Power Factor The expression is:

[0025]

[0026] Active power P dc The expression is:

[0027] P dc =V dc I dc

[0028] Reactive power Q dc The expression is:

[0029]

[0030] Where V ac is the AC bus voltage of the converter valve, I dc is the DC current, X c is the equivalent commutation resistance, which is proportional to the commutation impedance, and β is the leading trigger angle on the inverter side;

[0031] The formula of the rectifier-side converter corresponds to that of the inverter-side converter, but the rectifier-side delayed trigger angle α is used instead of the inverter-side shutdown angle γ.

[0032] Optionally, the smoothing reactor adopts an inductor dynamic model; the DC connection line adopts an inductor-resistor series dynamic model; the fault grounding branch adopts a resistor-inductor series or a resistor-capacitor series dynamic model; the DC filter adopts an inductor, resistor, and capacitor series-parallel dynamic model; the equivalent diode is a variable resistor, and its resistance R D Press the formula to change:

[0033]

[0034] Where V pn It is the voltage drop between the positive and negative terminals.

[0035] Optionally, the secondary model library includes a control sub-model library, a protection sub-model library and an operation sub-model library for simulating the functions of monitoring, controlling and protecting the primary part, wherein:

[0036] The control sub-model library includes a basic control unit and an auxiliary control unit, wherein the basic control unit includes a main control module, an overload limiting module, a current margin compensation module, a constant current control module, a constant voltage control module, a rectifier side minimum trigger angle control module, a GAMMA0 control module, a low voltage current limiting module, an AMAX control module and a commutation failure prediction module, and the auxiliary control unit includes an inverter side large angle control module, a low voltage current limiting switching strategy module, a current optimization control module and a dynamic voltage adjustment module;

[0037] The protection sub-model library includes a converter protection unit and a DC line protection unit, wherein the converter protection unit includes a low voltage protection module and a continuous commutation failure protection module; the DC line protection unit includes a differential protection module, a low voltage overcurrent protection module, an overvoltage protection module, a low voltage protection module and an overcurrent protection module;

[0038] The operation sub-model library includes a state adjustment module, a manual commutation failure setting module, a DC system restart module, and a converter locking module.

[0039] According to another aspect of the present invention, the present invention provides a method for electromechanical transient simulation of conventional direct current, the method comprising:

[0040] Calling a model from an electromechanical transient simulation model library according to a topological structure of a conventional DC to be simulated and a DC control system, and determining parameters of the called model to generate an electromechanical transient simulation model for simulating a conventional DC;

[0041] Setting simulation parameters of the electromechanical transient simulation model, the simulation parameters including simulation step lengths of conventional DC AC side and DC side to be simulated, total simulation calculation time, and simulation disturbances, the simulation disturbances including simulated faults and simulated operations;

[0042] Based on the simulation parameters, an electromechanical transient multi-rate simulation alternating iteration is performed on the electromechanical transient simulation model intended to simulate conventional direct current.

[0043] Optionally, calling a model from an electromechanical transient simulation model library according to the topological structure of a conventional DC to be simulated and a DC control system, and determining parameters of the called model to generate an electromechanical transient simulation model to be simulated, comprises:

[0044] According to the topological structure of conventional DC to be simulated and the DC control system, the corresponding models in the primary model library and the secondary model library are called from the electromechanical transient simulation model library;

[0045] Determine the corresponding model parameters according to the factory parameters of each device in the topological structure of conventional DC to be simulated;

[0046] The DC control system that simulates conventional DC is modeled using the principle of classified equivalent centralized compensation, and the model parameters of the DC control system are determined.

[0047] Optionally, the method of adopting the classification equivalent centralized compensation principle to model a DC control system that is intended to simulate a conventional DC and determining the model parameters of the DC control system includes:

[0048] The various links of the DC control system are divided into core control links and non-core control links according to the degree of impact on the safety of the AC power grid, the nature of input and output, and the degree of matching with the electromechanical transient network. Among them, the core control links are the constant DC current control link and the constant DC voltage control link.

[0049] The non-core control links are each equivalent according to their own principles and characteristics as their model parameters;

[0050] The core control link compensates for the simulation deviation of the entire DC control system, completes the parameter fitting, and determines the model parameters of the core control link. Specifically, the parameters of each link are adjusted under different AC and DC faults to make the simulation curve closest to the equipment characteristics. When different faults have different parameter requirements, priority is given to meeting the needs of high-power harsh working conditions.

[0051] Optionally, setting the simulation step size of the AC side and the DC side of the conventional DC to be simulated includes:

[0052] The first simulation step is used for the AC side, and the second simulation step is used for the DC side. The dividing point between the AC side and the DC side is the high-voltage busbar of the converter.

[0053] The second simulation step is determined according to the electrical distance between the fault and the DC, as well as the research objectives;

[0054] The first simulation step size is larger than the second simulation step size.

[0055] Optionally, performing electromechanical transient multi-rate simulation alternating iteration on the electromechanical transient simulation model intended to simulate conventional direct current based on the simulation parameters includes:

[0056] Step 1: At each simulation step on the AC side, set the voltage at the end of the time step to be equal to the voltage at the beginning of the time step;

[0057] Step 2: perform linear interpolation between the converter station AC bus voltages at the beginning and end of each AC side simulation step to obtain the converter station AC voltage for each DC side simulation step;

[0058] Step 3: Use the historical current source method and the integral switching method to solve the DC side system, and obtain the active current and reactive current injected into the AC grid by the DC side system;

[0059] Step 4: Solve the models of other devices connected in parallel to the AC power grid to obtain the active current and reactive current injected into the AC power grid by each device;

[0060] Step 5, solve the AC power grid admittance matrix to obtain the AC voltage of the entire network at the end of the simulation step length of the AC side;

[0061] Step 6: Compare the calculated deviation between the AC voltage at the end of this time step and the voltage at the end of this time step used for this round of iteration. If the deviation is less than the convergence threshold, the calculation of this time step ends and the calculation of the next time step begins. The initial voltage of the next time step is the calculated AC voltage at the end of this time step. If the deviation is greater than the convergence threshold, go to step 2 to enter the next round of iteration.

[0062] Optionally, the adopting of the historical current source method and the integral switching method to solve the DC side system to obtain the active current and reactive current injected into the AC grid by the DC side system includes:

[0063] The historical current source method is used to convert the historical value of the component model into a current source hung on both sides of the component at this time step, and the expression related to the voltage at this time step in the component model is converted into resistance. The dynamic network solution at each time step is converted into a resistive network solution.

[0064] When there is no operation inside the DC side network, the implicit trapezoidal integration method is used to solve the DC side system. When there is a DC side network fault or line switching, the backward Euler integration method is used to solve the DC side system.

[0065] According to another aspect of the present invention, the present invention provides an electromechanical transient simulation device for conventional direct current, the device comprising:

[0066] A model building unit is used to call a corresponding model from an electromechanical transient simulation model library according to a topological structure of a conventional DC to be simulated and a DC control system to generate an electromechanical transient simulation model for simulating a conventional DC;

[0067] A calculation setting unit is used to set the simulation step size, total calculation time, output information, fault operation and other disturbances of the AC side and the DC side of the conventional DC to be simulated;

[0068] The dynamic simulation unit is used to simulate the electromechanical transient simulation model intended to simulate conventional direct current based on the simulation step size.

[0069] According to another aspect of the present invention, the present invention provides a computer-readable storage medium, wherein the storage medium stores a computer program, and the computer program is used to execute the method described in any one of the above aspects of the present invention.

[0070] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; the processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of the above aspects of the present invention.

[0071] The electromechanical transient simulation model library, simulation method and device for conventional direct current described in the present invention, wherein the model library includes a primary model library and a secondary model library established based on a generalized modeling idea, specifically, the primary model library is composed of component models generated by modeling high-voltage circuit elements, wherein the high-voltage circuit elements are generated by decomposing the primary part of an existing conventional direct current project; the secondary model library is composed of module models generated by modeling an operation control module, wherein the operation control module is generated by decomposing the secondary part of an existing conventional direct current project. Based on the idea of ​​generalized modeling, the present invention decomposes the primary part and the secondary part of an existing conventional direct current project, generates various generalized models to constitute an electromechanical transient simulation model library, thereby being able to describe as many projects as possible with as little code as possible, reducing the amount of development of new direct current models, and enabling users to construct a new direct current model through simple operations. Furthermore, when establishing an electromechanical transient simulation model of conventional direct current, a modeling method based on classified equivalent centralized compensation is used to determine the model parameters of the direct current control system, thereby improving the accuracy of constructing an electromechanical transient model. After successfully constructing an electromechanical transient simulation model that simulates conventional DC, the present invention adopts a multi-rate alternating iteration method for simulation, solves the DC circuit based on the historical current source method, and adopts an integral switching method to take into account both calculation accuracy and stability, thereby achieving full coordination of accuracy, speed and stability of electromechanical transient simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0073] Figure 1 A schematic diagram of the structure of an electromechanical transient simulation model library for conventional direct current according to a preferred embodiment of the present invention;

[0074] Figure 2 A flowchart of an electromechanical transient simulation method for conventional direct current according to a preferred embodiment of the present invention;

[0075] Figure 3 A schematic diagram of the structure of an electromechanical transient simulation device for conventional direct current according to a preferred embodiment of the present invention;

[0076] Figure 4 Schematic diagram of the structure of an electronic device according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0077] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0078] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0079] Example Model Library

[0080] Figure 1 FIG. 1 is a schematic diagram of the structure of an electromechanical transient simulation model library for conventional DC according to a preferred embodiment of the present invention. Figure 1 As shown, the electromechanical transient simulation model library 100 described in this preferred embodiment includes a primary model library 101 and a secondary model library 102 established based on a universal modeling idea, wherein:

[0081] The primary model library 101 is composed of component models generated by modeling high-voltage circuit components, wherein the high-voltage circuit components are generated by decomposing the primary part of an existing conventional DC project;

[0082] The secondary model library 102 is composed of module models generated by modeling the operation control module, wherein the operation control module is generated by decomposing the secondary part of an existing conventional DC project.

[0083] Preferably, the primary model library 101 includes an AC sub-model library for AC side equivalent circuit simulation and a DC sub-model library for DC side equivalent circuit simulation, wherein:

[0084] The AC sub-model library includes models established for converter transformers and parallel compensation devices;

[0085] The DC sub-model library includes models established for a DC converter, a DC line, a smoothing reactor, a DC connecting line, a fault grounding branch, a DC filter and an equivalent diode.

[0086] Preferably, the model of the converter transformer established in the AC side sub-model library only includes the ideal transformation ratio, and the transformer body loss impedance is realized by establishing an impedance model in the DC sub-model library.

[0087] Preferably, the DC converter uses a quasi-steady-state formula to describe its model, wherein the formula of the inverter-side converter is as follows:

[0088] DC no-load open circuit voltage V d0 The expression is:

[0089]

[0090] Commutation voltage drop ΔV dc The expression is:

[0091]

[0092] DC line voltage V dc The expression is:

[0093] V dc =V d0 cosβ+ΔV dc

[0094] The expression of the commutation angle μ is:

[0095]

[0096] The expression of the cut-off angle γ is:

[0097] γ=β-μ

[0098] Power Factor The expression is:

[0099]

[0100] Active power P dc The expression is:

[0101] P dc =V dc I dc

[0102] Reactive power Q dc The expression is:

[0103]

[0104] Where V ac is the AC bus voltage of the converter valve, I dc is the DC current, X c is the equivalent commutation resistance, which is proportional to the commutation impedance, and β is the leading trigger angle on the inverter side;

[0105] The formula of the rectifier-side converter corresponds to that of the inverter-side converter, but the rectifier-side delayed trigger angle α is used instead of the inverter-side shutdown angle γ.

[0106] Preferably, the smoothing reactor adopts an inductor dynamic model; the DC connection line adopts an inductor-resistor series dynamic model; the fault grounding branch adopts a resistor-inductor series or a resistor-capacitor series dynamic model; the DC filter adopts an inductor, resistor, and capacitor series-parallel dynamic model; the equivalent diode is a variable resistor, and its resistance R D Press the formula to change:

[0107]

[0108] Where V pn It is the voltage drop between the positive and negative terminals.

[0109] Preferably, the secondary model library 102 includes a control sub-model library, a protection sub-model library and an operation sub-model library for simulating the functions of monitoring, controlling and protecting the primary part, wherein:

[0110] The control sub-model library includes a basic control unit and an auxiliary control unit, wherein the basic control unit includes a main control module, an overload limiting module, a current margin compensation module, a constant current control module, a constant voltage control module, a rectifier side minimum trigger angle control module, a GAMMA0 control module, a low voltage current limiting module, an AMAX control module and a commutation failure prediction module, and the auxiliary control unit includes an inverter side large angle control module, a low voltage current limiting switching strategy module, a current optimization control module and a dynamic voltage adjustment module;

[0111] The protection sub-model library includes a converter protection unit and a DC line protection unit, wherein the converter protection unit includes a low voltage protection module and a continuous commutation failure protection module; the DC line protection unit includes a differential protection module, a low voltage overcurrent protection module, an overvoltage protection module, a low voltage protection module and an overcurrent protection module;

[0112] The operation sub-model library includes a state adjustment module, a manual commutation failure setting module, a DC system restart module, and a converter locking module.

[0113] The electromechanical transient simulation model library for conventional DC described in this preferred embodiment is constructed based on a universal modeling idea, which can be understood as a union of different engineering models, decomposing the primary part of each engineering into high-voltage circuit elements, and the secondary part into operation control modules, allowing flexible combinations between circuit elements, between functional modules, and between primary and secondary, and providing convenient combination means, so that users can construct new DC models only through simple operations. In this way, as many engineering projects as possible can be described with as little code as possible, reducing the development of new DC models, and facilitating comparative studies of new engineering models.

[0114] Exemplary Methods

[0115] Figure 2 FIG. 1 is a flow chart of an electromechanical transient simulation method for conventional direct current according to a preferred embodiment of the present invention. Figure 2 As shown, the electromechanical transient simulation method for conventional direct current described in this preferred embodiment starts from step 201 .

[0116] In step 201, a model is called from an electromechanical transient simulation model library according to the topological structure of the conventional DC to be simulated and the DC control system, and parameters of the called model are determined to generate an electromechanical transient simulation model to be simulated for the conventional DC.

[0117] Preferably, calling a model from an electromechanical transient simulation model library according to the topological structure of the conventional DC to be simulated and the DC control system, and determining the parameters of the called model to generate an electromechanical transient simulation model to simulate the conventional DC, comprises:

[0118] According to the topological structure of conventional DC to be simulated and the DC control system, the corresponding models in the primary model library and the secondary model library are called from the electromechanical transient simulation model library;

[0119] Determine the corresponding model parameters according to the factory parameters of each device in the topological structure of conventional DC to be simulated;

[0120] The DC control system that simulates conventional DC is modeled using the principle of classified equivalent centralized compensation, and the model parameters of the DC control system are determined.

[0121] Preferably, the method of adopting the classification equivalent centralized compensation principle to model a DC control system that simulates conventional DC and determining the model parameters of the DC control system includes:

[0122] The various links of the DC control system are divided into core control links and non-core control links according to the degree of impact on the safety of the AC power grid, the nature of input and output, and the degree of matching with the electromechanical transient network. Among them, the core control links are the constant DC current control link and the constant DC voltage control link.

[0123] The non-core control links are each equalized according to their own principles and characteristics as their model parameters. For example, for links with switch action characteristics, the main characteristics and parameters are completely retained; links lacking variable support are ignored or simplified; links with complex filtering can simplify the filter;

[0124] The core control link compensates for the simulation deviation of the entire DC control system, completes the parameter fitting, and determines the model parameters of the core control link. Specifically, the parameters of each link are adjusted under different AC and DC faults to make the simulation curve closest to the equipment characteristics. When different faults have different parameter requirements, priority is given to meeting the needs of high-power harsh working conditions.

[0125] In this preferred embodiment, since the DC control system has a large number of links, logic blocks, and parameters, modeling them one by one in the electromechanical transient state according to the actual equipment will make the calculation speed very slow. Therefore, the present invention determines the model parameters of the DC control system based on the modeling method of classified equivalent centralized compensation, which greatly improves the accuracy of the simulation results.

[0126] In step 202, simulation parameters of the electromechanical transient simulation model are set, wherein the simulation parameters include a simulation step size for simulating conventional DC AC side and DC side, a total simulation calculation time, and a simulation disturbance, wherein the simulation disturbance includes a simulated fault and a simulated operation.

[0127] Preferably, the step of setting the simulation step of the AC side and the DC side of the conventional DC to be simulated includes:

[0128] The first simulation step is used for the AC side, and the second simulation step is used for the DC side. The dividing point between the AC side and the DC side is the high-voltage busbar of the converter.

[0129] The second simulation step is determined according to the electrical distance between the fault and the DC, as well as the research objectives;

[0130] The first simulation step size is larger than the second simulation step size.

[0131] In this preferred embodiment, since the DC components have fast action speed and small time constant, a smaller simulation step is required to clearly describe the dynamic behavior of the DC system; while the AC power grid has many ferromagnetic components characterized by generators and motors, and the fundamental wave dynamic process is slow, which allows the use of a larger simulation step to adapt to the situation of a large number of components in the large power grid. Therefore, multi-rate simulation using a large step for the AC side power grid that is intended to simulate conventional DC and a small step for the DC side becomes an effective method to solve the problem of different simulation step sizes for the AC and DC sides.

[0132] In step 203, based on the simulation parameters, an electromechanical transient multi-rate simulation alternating iteration is performed on the electromechanical transient simulation model intended to simulate conventional direct current.

[0133] Preferably, the electromechanical transient multi-rate simulation alternating iteration is performed on the electromechanical transient simulation model intended to simulate conventional direct current based on the simulation parameters, comprising:

[0134] Step 1: At each simulation step on the AC side, set the voltage at the end of the time step to be equal to the voltage at the beginning of the time step;

[0135] Step 2: perform linear interpolation between the converter station AC bus voltages at the beginning and end of each AC side simulation step to obtain the converter station AC voltage for each DC side simulation step;

[0136] Step 3: Use the historical current source method and the integral switching method to solve the DC side system, and obtain the active current and reactive current injected into the AC grid by the DC side system;

[0137] Step 4: Solve the models of other devices connected in parallel to the AC power grid to obtain the active current and reactive current injected into the AC power grid by each device;

[0138] Step 5, solve the AC power grid admittance matrix to obtain the AC voltage of the entire network at the end of the simulation step length of the AC side;

[0139] Step 6: Compare the calculated deviation between the AC voltage at the end of this time step and the voltage at the end of this time step used for this round of iteration. If the deviation is less than the convergence threshold, the calculation of this time step ends and the calculation of the next time step begins. The initial voltage of the next time step is the calculated AC voltage at the end of this time step. If the deviation is greater than the convergence threshold, go to step 2 to enter the next round of iteration.

[0140] Preferably, the method of solving the DC side system by using the historical current source method and the integral switching method to obtain the active current and reactive current injected into the AC grid by the DC side system includes:

[0141] The historical current source method is used to convert the historical value of the component model into a current source hung on both sides of the component at this time step, and the expression related to the voltage at this time step in the component model is converted into resistance. The dynamic network solution at each time step is converted into a resistive network solution.

[0142] When there is no operation inside the DC side network, the implicit trapezoidal integration method is used to solve the DC side system. When there is a DC side network fault or line switching, the backward Euler integration method is used to solve the DC side system.

[0143] The historical current source method for solving the DC circuit in this preferred embodiment is the same as the historical current source method for solving the dynamic network in the electromagnetic transient program EMTP. This method converts the historical value of the component model into a current source hanging on both sides of the component at this time step, converts the expression related to the voltage at this time step in the component model into resistance, and converts the dynamic network solution at each time step into solving the resistive network. The network admittance does not change when the topological structure does not change, and only the current at both ends of the component needs to be updated at each time step. The solution is simple, fast, and has strong adaptability to different integration methods.

[0144] The electromechanical transient simulation method for conventional DC described in this preferred embodiment uses the models corresponding to the AC side and the DC side of the conventional DC to be simulated to be called from the electromechanical transient simulation model library generated based on the universal modeling idea, and the DC control system is modeled based on the classified equivalent centralized compensation to determine the model parameters to generate an electromechanical transient simulation model for simulating conventional DC, and the historical current source method and the integral switching method are used to solve the DC system, and the multi-rate simulation is used for alternating iterations to perform simulation calculations, thereby reducing the development of new DC models and achieving full coordination of accuracy, speed and stability of electromechanical transient simulation of conventional DC.

[0145] Exemplary Devices

[0146] Figure 3 FIG. 1 is a schematic diagram of a conventional direct current electromechanical transient simulation device according to a preferred embodiment of the present invention. Figure 3 As shown, the electromechanical transient simulation device 300 for conventional direct current described in this preferred embodiment includes:

[0147] The model building unit 301 is used to call the corresponding model from the electromechanical transient simulation model library according to the topological structure of the conventional DC to be simulated and the DC control system to generate an electromechanical transient simulation model for simulating the conventional DC;

[0148] The calculation setting unit 302 is used to set the simulation step size, total calculation time, output information, fault operation and other disturbances of the AC side and the DC side of the conventional DC to be simulated;

[0149] The dynamic simulation unit 303 is used to simulate the electromechanical transient simulation model intended to simulate conventional direct current based on the simulation step size.

[0150] Preferably, the model building unit 301 calls a model from an electromechanical transient simulation model library according to the topological structure of the conventional DC to be simulated and the DC control system, and determines the parameters of the called model to generate an electromechanical transient simulation model to simulate the conventional DC, including:

[0151] According to the topological structure of conventional DC to be simulated and the DC control system, the corresponding models in the primary model library and the secondary model library are called from the electromechanical transient simulation model library;

[0152] Determine the corresponding model parameters according to the factory parameters of each device in the topological structure of conventional DC to be simulated;

[0153] The DC control system that simulates conventional DC is modeled using the principle of classified equivalent centralized compensation, and the model parameters of the DC control system are determined.

[0154] Preferably, the model building unit 301 adopts the classification equivalent centralized compensation principle to model the DC control system that simulates the conventional DC and determines the model parameters of the DC control system, including:

[0155] The various links of the DC control system are divided into core control links and non-core control links according to the degree of impact on the safety of the AC power grid, the nature of input and output, and the degree of matching with the electromechanical transient network. Among them, the core control links are the constant DC current control link and the constant DC voltage control link.

[0156] The non-core control links are each equivalent according to their own principles and characteristics as their model parameters;

[0157] The core control link compensates for the simulation deviation of the entire DC control system, completes the parameter fitting, and determines the model parameters of the core control link. Specifically, the parameters of each link are adjusted under different AC and DC faults to make the simulation curve closest to the equipment characteristics. When different faults have different parameter requirements, priority is given to meeting the needs of high-power harsh working conditions.

[0158] Preferably, the calculation setting unit 302 sets the simulation step size of the AC side and the DC side of the conventional DC simulation, including:

[0159] The first simulation step is used for the AC side, and the second simulation step is used for the DC side. The dividing point between the AC side and the DC side is the high-voltage busbar of the converter.

[0160] The second simulation step is determined according to the electrical distance between the fault and the DC, as well as the research objectives;

[0161] The first simulation step size is larger than the second simulation step size.

[0162] Preferably, the dynamic simulation unit 303 performs electromechanical transient multi-rate simulation alternating iteration on the electromechanical transient simulation model intended to simulate conventional direct current based on the simulation parameters, including:

[0163] Step 1: At each simulation step on the AC side, set the voltage at the end of the time step to be equal to the voltage at the beginning of the time step;

[0164] Step 2: perform linear interpolation between the converter station AC bus voltages at the beginning and end of each AC side simulation step to obtain the converter station AC voltage for each DC side simulation step;

[0165] Step 3: Use the historical current source method and the integral switching method to solve the DC side system, and obtain the active current and reactive current injected into the AC grid by the DC side system;

[0166] Step 4: Solve the models of other devices connected in parallel to the AC power grid to obtain the active current and reactive current injected into the AC power grid by each device;

[0167] Step 5, solve the AC power grid admittance matrix to obtain the AC voltage of the entire network at the end of the simulation step length of the AC side;

[0168] Step 6: Compare the calculated deviation between the AC voltage at the end of this time step and the voltage at the end of this time step used for this round of iteration. If the deviation is less than the convergence threshold, the calculation of this time step ends and the calculation of the next time step begins. The initial voltage of the next time step is the calculated AC voltage at the end of this time step. If the deviation is greater than the convergence threshold, go to step 2 to enter the next round of iteration.

[0169] Preferably, the dynamic simulation unit 303 uses a historical current source method and an integral switching method to solve the DC side system, and obtains the active current and reactive current injected into the AC grid by the DC side system, including:

[0170] The historical current source method is used to convert the historical value of the component model into a current source hung on both sides of the component at this time step, and the expression related to the voltage at this time step in the component model is converted into resistance. The dynamic network solution at each time step is converted into a resistive network solution.

[0171] When there is no operation inside the DC side network, the implicit trapezoidal integration method is used to solve the DC side system. When there is a DC side network fault or line switching, the backward Euler integration method is used to solve the DC side system.

[0172] The steps of modeling and electromechanical transient simulation of the conventional DC to be simulated by the electromechanical transient simulation device for conventional DC described in this preferred embodiment are the same as the steps of the electromechanical transient simulation method for conventional DC described in the present invention, and the technical effects achieved are also the same, which will not be repeated here.

[0173] Exemplary Electronic Devices

[0174] Figure 4 The electronic device may be any one or both of the first device and the second device, or a stand-alone device independent of them, and the stand-alone device may communicate with the first device and the second device to receive the collected input signals from them. Figure 4 FIG. 1 is a block diagram of an electronic device according to an embodiment of the present disclosure. Figure 4 As shown, the electronic device includes one or more processors 401 and a memory 402 .

[0175] The processor 401 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0176] The memory 402 may include one or more computer program products, and the computer program product may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 401 may run the program instructions to implement the energy consumption anomaly diagnosis method based on the enterprise energy consumption space of each disclosed embodiment described above and / or other desired functions. In one example, the electronic device may also include: an input device 403 and an output device 404, which are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0177] In addition, the input device 403 may also include, for example, a keyboard, a mouse, and the like.

[0178] The output device 404 can output various information to the outside, and can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0179] Of course, to simplify, Figure 4 Only some of the components related to the present disclosure in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, according to specific application situations, the electronic device may further include any other appropriate components.

[0180] Exemplary computer program products and computer-readable storage media

[0181] In addition to the above-mentioned methods and devices, an embodiment of the present disclosure may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to execute the steps of the electromechanical transient simulation method for conventional direct current according to various embodiments of the present disclosure described in the above-mentioned "Exemplary Method" section of this specification.

[0182] The computer program product may be written in any combination of one or more programming languages ​​to write program code for performing the operations of the disclosed embodiments, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0183] In addition, an embodiment of the present disclosure may also be a computer-readable storage medium having computer program instructions stored thereon, and when the computer program instructions are executed by a processor, the processor executes the steps of the electromechanical transient simulation method for conventional direct current according to various embodiments of the present disclosure described in the above “Exemplary Method” section of this specification.

[0184] The computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0185] The basic principles of the present disclosure are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limitations. The above details do not limit the present disclosure to the necessity of adopting the above specific details to be implemented.

[0186] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system embodiment, since it basically corresponds to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0187] The block diagrams of the devices, apparatuses, equipment, and systems involved in this disclosure are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including," "comprising," "having," and the like are open words, referring to "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or," and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0188] The method and apparatus of the present disclosure may be implemented in many ways. For example, the method and apparatus of the present disclosure may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above order of steps for the method is for illustration only, and the steps of the method of the present disclosure are not limited to the order specifically described above, unless otherwise specifically stated. In addition, in some embodiments, the present disclosure may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present disclosure. Therefore, the present disclosure also covers a recording medium storing a program for executing the method according to the present disclosure.

[0189] It should also be noted that in the apparatus, equipment and method of the present disclosure, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present disclosure. The above description of the disclosed aspects is provided to enable any technician in the field to make or use the present disclosure. Various modifications to these aspects are very obvious to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown here, but to the widest scope consistent with the principles and novel features disclosed herein.

[0190] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A electromechanical transient simulation model library for conventional direct current, characterized in that: The model library includes a primary model library and a secondary model library established based on a generalized modeling idea, wherein: The primary model library is composed of component models generated by modeling high-voltage circuit components, wherein the high-voltage circuit components are generated by decomposing the primary part of an existing conventional DC project; The secondary model library is composed of module models generated by modeling the operation control module, wherein the operation control module is generated by decomposing the secondary part of an existing conventional direct current project.

2. The model library according to claim 1, characterized in that: The primary model library includes an AC sub-model library for AC side equivalent circuit simulation and a DC sub-model library for DC side equivalent circuit simulation, wherein: The AC sub-model library includes models established for converter transformers and parallel compensation devices; The DC sub-model library includes models established for a DC converter, a DC line, a smoothing reactor, a DC connecting line, a fault grounding branch, a DC filter and an equivalent diode.

3. The model library according to claim 2, characterized in that: The model of the converter transformer established in the AC side sub-model library only includes the ideal transformation ratio, and the transformer body loss impedance is realized by establishing an impedance model in the DC sub-model library.

4. The model library according to claim 2, characterized in that: The DC converter uses a quasi-steady-state formula to describe its model, wherein the formula of the inverter-side converter is as follows: The expression of DC no-load open circuit voltage Vd0 is: The expression of commutation voltage drop ΔVdc is: The expression of DC line terminal voltage Vdc is: Vdc=Vd0 cosβ+ΔVdc The expression of the commutation angle μ is: The expression of the cut-off angle γ is: γ=β-μ Power Factor The expression is: Active power P dc The expression is: P dc =V dc I dc Reactive power Q dc The expression is: Where V ac is the AC bus voltage of the converter valve, I dc is the DC current, X c is the equivalent commutation resistance, which is proportional to the commutation impedance, and β is the leading trigger angle on the inverter side; The formula of the rectifier-side converter corresponds to that of the inverter-side converter, but the rectifier-side delayed trigger angle α is used instead of the inverter-side shutdown angle γ.

5. The model library according to claim 2, characterized in that: The smoothing reactor adopts the inductor dynamic model; the DC connecting line adopts the inductor resistor series dynamic model; the fault grounding branch adopts the resistor inductor series or resistor capacitor series dynamic model; the DC filter adopts the inductor, resistor, capacitor series parallel dynamic model; the equivalent diode is a variable resistor, and its resistance R D Press the formula to change: Where V pn It is the voltage drop between the positive and negative terminals.

6. The model library according to claim 1, characterized in that: The secondary model library includes a control sub-model library, a protection sub-model library and an operation sub-model library for simulating the functions of monitoring, controlling and protecting the primary part, wherein: The control sub-model library includes a basic control unit and an auxiliary control unit, wherein the basic control unit includes a main control module, an overload limiting module, a current margin compensation module, a constant current control module, a constant voltage control module, a rectifier side minimum trigger angle control module, a GAMMA0 control module, a low voltage current limiting module, an AMAX control module and a commutation failure prediction module, and the auxiliary control unit includes an inverter side large angle control module, a low voltage current limiting switching strategy module, a current optimization control module and a dynamic voltage adjustment module; The protection sub-model library includes a converter protection unit and a DC line protection unit, wherein the converter protection unit includes a low voltage protection module and a continuous commutation failure protection module; the DC line protection unit includes a differential protection module, a low voltage overcurrent protection module, an overvoltage protection module, a low voltage protection module and an overcurrent protection module; The operation sub-model library includes a state adjustment module, a manual commutation failure setting module, a DC system restart module, and a converter locking module.

7. A method for electromechanical transient simulation of conventional direct current, characterized in that: The method comprises: Calling a model from an electromechanical transient simulation model library according to a topological structure of a conventional DC to be simulated and a DC control system, and determining parameters of the called model to generate an electromechanical transient simulation model for simulating a conventional DC; Setting simulation parameters of the electromechanical transient simulation model, wherein the simulation parameters include simulation step lengths of conventional DC AC side and DC side to be simulated, total simulation calculation time, and simulation disturbance data, wherein the simulation disturbance includes simulated faults and simulated operations; Based on the simulation parameters, an electromechanical transient multi-rate simulation alternating iteration is performed on the electromechanical transient simulation model intended to simulate conventional direct current.

8. The method according to claim 7, characterized in that The method of calling a model from an electromechanical transient simulation model library according to the topological structure of the conventional DC to be simulated and the DC control system, and determining the parameters of the called model to generate an electromechanical transient simulation model to simulate the conventional DC, comprises: According to the topological structure of conventional DC to be simulated and the DC control system, the corresponding models in the primary model library and the secondary model library are called from the electromechanical transient simulation model library; Determine the corresponding model parameters according to the factory parameters of each device in the topological structure of conventional DC to be simulated; The DC control system that simulates conventional DC is modeled using the principle of classified equivalent centralized compensation, and the model parameters of the DC control system are determined.

9. The method according to claim 8, characterized in that The method of adopting the classification equivalent centralized compensation principle to model the DC control system that is intended to simulate conventional DC and determine the model parameters of the DC control system includes: The various links of the DC control system are divided into core control links and non-core control links according to the degree of impact on the safety of the AC power grid, the nature of input and output, and the degree of matching with the electromechanical transient network. Among them, the core control links are the constant DC current control link and the constant DC voltage control link. The non-core control links are each equivalent according to their own principles and characteristics as their model parameters; The core control link compensates for the simulation deviation of the entire DC control system, completes the parameter fitting, and determines the model parameters of the core control link. Specifically, the parameters of each link are adjusted under different AC and DC faults to make the simulation curve closest to the equipment characteristics. When different faults have different parameter requirements, priority is given to meeting the needs of high-power harsh working conditions.

10. The method according to claim 7, characterized in that The step of setting the simulation step of the AC side and the DC side of the conventional DC to be simulated includes: The first simulation step is used for the AC side, and the second simulation step is used for the DC side. The dividing point between the AC side and the DC side is the high-voltage busbar of the converter. The second simulation step is determined according to the electrical distance between the fault and the DC, as well as the research objectives; The first simulation step size is larger than the second simulation step size.

11. The method according to claim 9, characterized in that The electromechanical transient multi-rate simulation is alternately iterated on the electromechanical transient simulation model intended to simulate conventional direct current based on the simulation parameters, including: Step 1: At each simulation step on the AC side, set the voltage at the end of the time step to be equal to the voltage at the beginning of the time step; Step 2: perform linear interpolation between the converter station AC bus voltages at the beginning and end of each AC side simulation step to obtain the converter station AC voltage for each DC side simulation step; Step 3: Use the historical current source method and the integral switching method to solve the DC side system, and obtain the active current and reactive current injected into the AC grid by the DC side system; Step 4: Solve the models of other devices connected in parallel to the AC power grid to obtain the active current and reactive current injected into the AC power grid by each device; Step 5, solve the AC power grid admittance matrix to obtain the AC voltage of the entire network at the end of the simulation step length of the AC side; Step 6: Compare the calculated deviation between the AC voltage at the end of this time step and the voltage at the end of this time step used for this round of iteration. If the deviation is less than the convergence threshold, the calculation of this time step ends and the calculation of the next time step begins. The initial voltage of the next time step is the calculated AC voltage at the end of this time step. If the deviation is greater than the convergence threshold, go to step 2 to enter the next round of iteration.

12. The method according to claim 11, characterized in that The method of using the historical current source method and the integral switching method to solve the DC side system and obtain the active current and reactive current injected into the AC grid by the DC side system includes: The historical current source method is used to convert the historical value of the component model into a current source hung on both sides of the component at this time step, and the expression related to the voltage at this time step in the component model is converted into resistance. The dynamic network solution at each time step is converted into a resistive network solution. When there is no operation inside the DC side network, the implicit trapezoidal integration method is used to solve the DC side system. When there is a DC side network fault or line switching, the backward Euler integration method is used to solve the DC side system.

13. An electromechanical transient simulation device for conventional direct current, characterized in that: The device comprises: A model building unit is used to call a corresponding model from an electromechanical transient simulation model library according to a topological structure of a conventional DC to be simulated and a DC control system to generate an electromechanical transient simulation model for simulating a conventional DC; A calculation setting unit is used to set the simulation step size, total calculation time, output information, fault operation and other disturbances of the AC side and the DC side of the conventional DC to be simulated; The dynamic simulation unit is used to simulate the electromechanical transient simulation model intended to simulate conventional direct current based on the simulation step size.

14. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 7 to 12.

15. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is used to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 7 to 12.

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