Method for solving current instantaneous value of series-parallel hybrid transformer based on thyristor control

Abstract

This application proposes a method for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control. The method includes: simulating a distribution network equipped with a Transformer-Controlled Transformer (TCHT) using a simulation application to obtain the conduction state of the thyristors during TCHT operation; determining the instantaneous voltage waveform based on the thyristor conduction state; modifying multiple parameters in each phase circuit of the TCHT based on the thyristor conduction state; modeling the instantaneous current flowing through the TCHT to obtain the instantaneous current equation; substituting the instantaneous voltage waveform and the modified parameters into the equation to solve for the initial instantaneous current value; and correcting the initial instantaneous current value based on the TCHT's state-switching protection requirements to obtain the instantaneous current waveform flowing through the TCHT. This method, by establishing TCHT instantaneous value models under different thyristor conduction states, can accurately solve for the instantaneous current flowing through the TCHT, improving the accuracy, convenience, and applicability of TCHT current instantaneous value calculation.

Description

Technical Field

[0001] This application relates to the field of power electronic equipment technology, and in particular to a method for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control. Background Technology

[0002] Currently, in order to accelerate the construction of a clean, low-carbon, safe, and efficient energy system, distributed power sources such as solar and wind power have been widely used in distribution networks. At the same time, with the rapid popularization of electric vehicles and their large-scale grid connection, the traditional open-loop operation mode can no longer meet the urgent needs of electricity users for reliable power supply and flexible operation of the distribution network.

[0003] The traditional operating model's inadequacy to current needs manifests in several ways, including bidirectional power flow, partial line overload, node voltage exceeding limits, frequent and severe load fluctuations, and blurred source-load boundaries. The root cause of these problems lies in the low reliability of the distribution network under the traditional open-loop operation mode. Therefore, interconnecting the distribution network is an effective solution. Flexible interconnection technology not only enables interconnection and power transfer within the distribution network but also provides power flow regulation. Consequently, key equipment and technologies for flexible interconnection in distribution networks are gaining increasing attention, and flexible interconnected distribution networks have become an important direction for distribution network development.

[0004] In related technologies, to meet practical application needs, thyristor-controlled series-parallel hybrid transformers (TCHTs) are gradually being promoted and applied in distribution networks. However, due to the control and switching state changes of thyristors involved in the operation of TCHTs, the nonlinearity of the distribution network's operating characteristics is enhanced. Furthermore, research on flexible interconnection devices in related technologies mainly focuses on the topology and steady-state models of flexible interconnection equipment, making it difficult to directly calculate the important instantaneous electrical quantities after TCHTs are connected to the distribution network, thus hindering the analysis of their dynamic characteristics in the distribution network.

[0005] Therefore, accurately determining the instantaneous current value of the TCHT during its operation after being connected to the distribution network has become an urgent problem to be solved. Summary of the Invention

[0006] This application aims to at least partially address one of the technical problems in the related art.

[0007] Therefore, the first objective of this application is to propose a method for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control. This method can accurately solve the instantaneous current value flowing through the TCHT by establishing a TCHT instantaneous value model under different thyristor conduction states, thereby improving the accuracy, convenience and applicability of TCHT instantaneous current value calculation and solving the problem of TCHT instantaneous current value modeling.

[0008] The second objective of this application is to propose a system for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control;

[0009] The third objective of this application is to provide a non-transitory computer-readable storage medium.

[0010] To achieve the above objectives, the first aspect of this application is to propose a method for solving the instantaneous value of current in a series-parallel hybrid transformer based on thyristor control, the method comprising the following steps:

[0011] Electromagnetic transient simulation was performed on a distribution network equipped with a thyristor-controlled series-parallel hybrid transformer (TCHT) using simulation applications. The conduction state of the thyristor was obtained when the TCHT regulated the power flow between different distribution areas, and the instantaneous voltage waveform was determined based on the conduction state of the thyristor.

[0012] For each phase circuit in the TCHT, multiple parameters in the circuit are modified by the conduction state of the thyristor, wherein the multiple parameters include the equivalent leakage inductance and voltage value of each winding subarray connected to the secondary circuit.

[0013] The instantaneous value model of the current flowing through the TCHT is performed to obtain the instantaneous current value equation, and the instantaneous voltage waveform and the modified multiple parameters are substituted into the instantaneous current value equation to calculate the initial instantaneous current value;

[0014] The initial instantaneous current value is corrected based on the state switching protection requirements of the TCHT to obtain the waveform of the instantaneous current flowing through the TCHT.

[0015] Optionally, in one embodiment of this application, determining the instantaneous voltage waveform based on the conduction state of the thyristor includes: performing steady-state modeling on a power distribution network simulation model; calculating the steady-state voltage across the TCHT in each conduction state based on the obtained steady-state model and the conduction state of the thyristor; converting the steady-state voltage value into an instantaneous voltage value and determining an instantaneous voltage value expression; and generating the instantaneous voltage waveform based on the instantaneous voltage value expression.

[0016] Optionally, in one embodiment of this application, the equivalent leakage inductance is calculated using the following formula:

[0017] L eq = aa*L1+bb*L1+cc*L1;

[0018] The voltage value is calculated using the following formula:

[0019]

[0020] Among them, u Aa u Ba and u Ca These represent the voltage outputs of the three-phase winding subarray, where (a, b, c) are the voltage coordinates corresponding to the three-phase winding subarray. The conduction state of the thyristor is represented by the coordinates (a, b, c), n T This represents the turns ratio of the parallel transformer, L1 is the equivalent leakage inductance of the first secondary winding of the parallel transformer, (aa, bb, cc) are the coefficients obtained by decoding the voltage coordinates (a, b, c), and u 1A u 1B and u 1C The voltages on the primary side of the three-phase parallel transformers.

[0021] Optionally, in one embodiment of this application, the instantaneous current value equation is represented by the following formula:

[0022]

[0023] Where, n a It is the turns ratio of a series transformer, L T It is the equivalent leakage inductance of the series transformer, i is the current flowing through the TCHT, and u is the equivalent leakage inductance of the series transformer. 1A and u 2A It is the voltage across the TCHT, R eq It is the equivalent resistance of each winding subarray;

[0024] The calculation of the initial instantaneous current value includes solving the instantaneous current value equation after substituting the parameters using the fourth-order Runge-Kutta method.

[0025] Optionally, in one embodiment of this application, the correction of the initial instantaneous current value based on the state switching protection requirement of the TCHT includes: determining the current zero-crossing time by fitting each of the initial instantaneous current values ​​with a sine wave; switching the thyristor conduction state at the current zero-crossing time to determine the waveform of the instantaneous current flowing through the TCHT after the state switching adjustment.

[0026] Optionally, in one embodiment of this application, the TCHT includes: a parallel excitation section, a thyristor-controlled valve-controlled voltage combination section, and a series voltage compensation section; wherein, the parallel excitation section includes three single-phase multi-winding transformers, the primary side of each transformer is connected in parallel to the distribution network system to obtain the system voltage, and the secondary side of each transformer corresponds to three winding subarrays.

[0027] To achieve the above objectives, a second aspect of this application also proposes a system for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control, comprising the following modules:

[0028] The simulation module is used to perform electromagnetic transient simulation on a distribution network equipped with a thyristor-controlled series-parallel hybrid transformer (TCHT) through a simulation application, obtain the conduction state of the thyristor when the TCHT performs power flow regulation between different distribution areas, and determine the instantaneous voltage waveform based on the conduction state of the thyristor.

[0029] The modification module is used to modify multiple parameters in each phase circuit of the TCHT by means of the conduction state of the thyristor, wherein the multiple parameters include the equivalent leakage inductance and voltage value of each winding subarray connected to the secondary circuit.

[0030] The calculation module is used to model the instantaneous value of the current flowing through the TCHT to obtain the instantaneous current value equation, and to substitute the instantaneous voltage waveform and the modified multiple parameters into the instantaneous current value equation to calculate the initial instantaneous current value;

[0031] The correction module is used to correct the initial instantaneous current value based on the state switching protection requirements of the TCHT to obtain the waveform of the instantaneous current flowing through the TCHT.

[0032] To implement the above embodiments, a third aspect of this application also proposes a non-transitory computer-readable storage medium storing a computer program thereon. When the computer program is executed by a processor, it implements the method for solving the instantaneous value of the series-parallel hybrid transformer current based on thyristor control in the first aspect embodiment.

[0033] The technical solution provided by the embodiments of this application brings at least the following beneficial effects: This application solves the instantaneous value of TCHT current based on the thyristor conduction state, fully analyzes the topology and control principle of TCHT, establishes the instantaneous value model of TCHT under different thyristor conduction states, and uses the voltage value across TCHT obtained from power flow calculation to solve the instantaneous value of the current flowing through TCHT. Therefore, the instantaneous value model of TCHT constructed in this application has high solution accuracy, can meet the analysis needs of distribution networks, and has a fast solution speed and wide applicability. It can effectively improve the dynamic analysis capability of distribution networks, effectively support the optimization of protection mechanisms based on current protection in distribution networks, and by accurately solving the instantaneous value of TCHT current, it is beneficial to identify fault points in distribution networks, improve the timeliness and effectiveness of fault handling, reduce the harm caused by faults, and improve the stability and reliability of distribution networks.

[0034] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0035] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0036] Figure 1 A flowchart illustrating a method for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control, as proposed in an embodiment of this application;

[0037] Figure 2 This is a schematic diagram of the topology of a series-parallel hybrid transformer based on thyristor control proposed in an embodiment of this application;

[0038] Figure 3 This is a schematic diagram of a medium-voltage distribution network simulation model equipped with TCHT, as proposed in an embodiment of this application.

[0039] Figure 4 This is a schematic diagram comparing a simulated current waveform with a waveform obtained by solving for the instantaneous value, as proposed in an embodiment of this application.

[0040] Figure 5 This is a schematic diagram illustrating the principle of a specific TCHT current instantaneous value calculation process proposed in an embodiment of this application;

[0041] Figure 6 This is a schematic diagram of a system for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control, as proposed in an embodiment of this application. Detailed Implementation

[0042] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0043] It should be noted that the key equipment for flexible interconnection in the relevant embodiments, designed for distribution networks, can no longer meet the application requirements of distribution networks. For example, the phase-shifting transformer (PST) is a typical electromagnetic flexible interconnection device. However, such equipment uses mechanical switches with slow response speed and short lifespan to adjust the compensation voltage, resulting in drawbacks such as long response time and complex operation and maintenance. With the development of power electronics technology, all-power electronic flexible interconnection equipment, represented by the Unified Power Flow Controller (UPFC), has been widely used. However, its high cost, large size, and difficult operation and maintenance limit its widespread application in distribution networks.

[0044] To meet practical needs, this application proposes a novel series-parallel flexible interconnection equipment based on semi-controlled power electronic devices and a "Sen" transformer, namely, a thyristor-controlled series-parallel hybrid transformer (TCHT). TCHT has a wider compensation range, can quickly achieve cross-level voltage regulation, and is beneficial for the interconnection and transfer of power in distribution networks.

[0045] However, because the TCHT involves thyristor control and switching state changes during operation, its corresponding circuit is a typical time-varying circuit, leading to enhanced nonlinearity in the distribution network's operating characteristics. Especially when the system is subjected to disturbances, the electrical quantities of the TCHT and the distribution network are difficult to express analytically, and important instantaneous electrical quantities cannot be directly calculated. Existing research mainly focuses on the topology and steady-state models of flexible interconnection equipment, with relatively little analysis of its transient models after integration into the distribution network.

[0046] Therefore, this application proposes a method for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control. This method can accurately solve the instantaneous current value during the operation of the TCHT, which helps to better analyze its dynamic characteristics in the distribution network and improve the transient stability of the distribution network.

[0047] The following description, with reference to the accompanying drawings, describes a method and system for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control, as proposed in an embodiment of the present invention.

[0048] Figure 1This is a flowchart illustrating a method for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control, as proposed in an embodiment of this application. Figure 1 As shown, the method includes the following steps:

[0049] Step S101: Perform electromagnetic transient simulation on the distribution network equipped with a thyristor-controlled series-parallel hybrid transformer (TCHT) through simulation application, obtain the conduction state of the thyristor when the TCHT performs power flow regulation between different distribution areas, and determine the instantaneous voltage waveform based on the conduction state of the thyristor.

[0050] Specifically, this step first uses simulation software to model the distribution network containing the TCHT in order to calculate the instantaneous voltage data. To more clearly explain the principle of solving the instantaneous TCHT current value in this application, the topology of the novel series-parallel flexible interconnection equipment TCHT targeted by this application will be described below.

[0051] In one embodiment of this application, the TCHT includes: a parallel excitation section, a thyristor-controlled valve-controlled voltage combination section, and a series voltage compensation section. The parallel excitation section includes three single-phase multi-winding transformers, with the primary winding of each transformer connected in parallel to the power distribution network system to obtain the system voltage, and the secondary winding of each transformer corresponding to three winding subarrays.

[0052] Specifically, in this embodiment, as Figure 2 As shown, the TCHT circuit has a series-parallel structure. Figure 2 The diagram uses dashed boxes to delineate three main parts: a parallel excitation section, a thyristor-controlled valve-controlled voltage combination section, and a series voltage compensation section. Different phases of the TCHT are distinguished by different colors. The parallel excitation section uses three single-phase multi-winding transformers. The primary windings are connected in parallel to the distribution network system to obtain the system voltage. Each secondary winding corresponds to three sub-winding arrays (which can be simply referred to as winding sub-arrays in this application). In this embodiment, the parallel transformer has two secondary windings, and the rated voltage ratio is 1:3, as an example for modeling.

[0053] Specifically, this application uses simulation software to perform electromagnetic transient simulation on a distribution network containing TCHT, and obtains the instantaneous current value data of TCHT when it performs power flow regulation between different distribution areas and the corresponding thyristor conduction state, that is, it obtains the current flowing through TCHT and the thyristor conduction state when TCHT performs power flow regulation.

[0054] As an example, the simulation model of a medium-voltage distribution network containing TCHT constructed in this application is as follows: Figure 3 As shown in Table 1 below, the specific parameters of the simulation model are as follows.

[0055] Table 1. Specific parameters of the simulation model

[0056]

[0057] Furthermore, based on the obtained simulation model and the acquired thyristor conduction state, the instantaneous voltage waveform of TCHT is calculated.

[0058] In one embodiment of this application, determining the instantaneous voltage waveform based on the conduction state of the thyristor includes: performing steady-state modeling on a power distribution network simulation model; calculating the steady-state voltage across the TCHT in each conduction state based on the obtained steady-state model and the conduction state of the thyristor; converting the steady-state voltage value into an instantaneous voltage value and determining the instantaneous voltage value expression; and generating the instantaneous voltage waveform based on the instantaneous voltage value expression.

[0059] Specifically, in this embodiment, steady-state modeling of the distribution network containing TCHT is performed. This can be achieved by further developing a steady-state model based on existing simulation models. Then, based on the thyristor conduction states and steady-state model corresponding to the simulation, the steady-state voltage value across the TCHT is calculated under each conduction state during power flow regulation. The waveform of the corresponding instantaneous voltage value is then plotted using the obtained steady-state voltage value. For example, each steady-state voltage value is converted into an instantaneous value, and an expression for the instantaneous voltage value is derived. Finally, the voltage waveform is plotted based on this instantaneous voltage value expression.

[0060] Step S102: For each phase circuit in TCHT, multiple parameters in the circuit are modified by the conduction state of the thyristor. These multiple parameters include the equivalent leakage inductance and voltage value of each winding subarray connected to the secondary circuit.

[0061] It should be noted that since the TCHT has a three-phase symmetrical structure, the three phases can be reduced to solving for one phase, and the solution method for each term is the same. Therefore, this application uses one phase, such as phase A, as an example to solve for the instantaneous current value. The solution process for the other phases is the same, and this application will not elaborate on it further.

[0062] Specifically, since the different conduction states of the thyristors will change the operating state of the circuit, the parameters in the circuit need to be modified according to the conduction state of the thyristors corresponding to the simulation.

[0063] In one embodiment of this application, the equivalent leakage inductance is calculated using the following formula:

[0064] L eq = aa*L1+bb*L1+cc*L1;

[0065] The voltage value is calculated using the following formula:

[0066]

[0067] Among them, u Aa u Ba and u Ca These represent the voltage outputs of the three-phase winding subarray, where (a, b, c) are the voltage coordinates corresponding to the three-phase winding subarray. The conduction state of the thyristor is represented by the coordinates (a, b, c), n T This represents the turns ratio of the parallel transformer, L1 is the equivalent leakage inductance of the first secondary winding of the parallel transformer, (aa, bb, cc) are the coefficients obtained by decoding the voltage coordinates (a, b, c), and u 1A u 1B and u 1C These are the voltages on the primary side of a three-phase parallel transformer.

[0068] In this embodiment, the conduction state of the thyristor in phase A winding can be represented by coordinates (a, b, c). Different thyristor conduction states will change the operating state of the circuit, and the corresponding coordinates will also change. Based on the conduction state of the thyristor corresponding to the simulation, the relevant parameter values ​​are substituted into the above two formulas to calculate the parameters in the modified circuit.

[0069] In the above formula, the parameters aa, bb, and cc correspond to the coordinates (a, b, c), and the relevant values ​​can be determined by referring to Table 2 below.

[0070] Table 2 Parameter Correspondence Table

[0071]

[0072] Step S103: The instantaneous value model of the current flowing through TCHT is performed to obtain the instantaneous current value equation, and the instantaneous voltage value waveform and the modified multiple parameters are substituted into the instantaneous current value equation to calculate the initial instantaneous current value.

[0073] Specifically, the instantaneous value of the current flowing through the TCHT is modeled to obtain the instantaneous current equation. Then, the instantaneous voltage waveform obtained in step S101 and the various parameters calculated in step S102 are substituted into the instantaneous current equation, and the current flowing through the TCHT is solved using relevant calculation methods.

[0074] In one embodiment of this application, the instantaneous current equation is expressed by the following formula:

[0075]

[0076] Where, n a It is the turns ratio of a series transformer, L T It is the equivalent leakage inductance of the series transformer, i is the current flowing through the TCHT, and u is the equivalent leakage inductance of the series transformer. 1A and u 2AThis refers to the voltage across the TCHT terminals. Since this embodiment uses phase A as an example for the solution, the voltage u on the primary side of phase A is used here. 1A and the voltage u on the secondary side 2A Perform the calculation, R eq It is the equivalent resistance of each winding subarray.

[0077] In this embodiment, the equivalent leakage inductance L calculated in step S102 is... eq and voltage value u eq Substitute the values ​​into the above equation, and use the voltage u across the TCHT calculated in step S101. 1A and u 2A Substitute the parameters into the above equation. Then use the fourth-order Runge-Kutta method to solve the equation after substituting the parameters, and preliminarily calculate the current flowing through the TCHT, that is, solve for the preliminary instantaneous value of the current.

[0078] Step S104: Based on the TCHT state switching protection requirements, the initial instantaneous current value is corrected to obtain the waveform of the instantaneous current flowing through the TCHT.

[0079] Specifically, in the TCHT, to avoid short circuits in the windings during thyristor state switching, the trigger signal for the next thyristor state can only be sent after all thyristors in the previous state have been reliably turned off. The thyristor turn-off time should be when the current crosses zero and the reverse voltage persists for a certain period. Therefore, the instantaneous current value obtained in step S103 needs to be corrected to obtain the final instantaneous current waveform of the TCHT.

[0080] In one embodiment of this application, the correction of the instantaneous value of the initial current based on the state switching protection requirement of the TCHT includes: determining the time when the current crosses zero by fitting each initial instantaneous current value with a sine wave; switching the conduction state of the thyristor at the time when the current crosses zero, and determining the waveform of the instantaneous current flowing through the TCHT after the state switching adjustment.

[0081] Specifically, in this embodiment, since reliable turn-off of the thyristor requires the current to cross zero and a certain reverse voltage to be maintained, the instantaneous current value obtained in step S103 is fitted with a sine wave to accurately determine the time point of current zero crossing. Then, at the moment of current zero crossing, the conduction state of the thyristor is switched, and finally, the corrected instantaneous current waveform is obtained. The correction process may involve adjusting the waveform according to the actual conduction state switching, re-determining the thyristor conduction state according to the state switching requirements, and adjusting the TCHT instantaneous value model established in the above embodiment for different thyristor conduction states.

[0082] To more fully illustrate the instantaneous current value calculation results of this application, as an example, for phase A of TCHT, the current waveform calculated according to the instantaneous current value calculation method of this application was compared with the thyristor simulation current obtained by simulation in step S101. The comparison results are as follows: Figure 4 As shown, Figure 4 Different colors are used to distinguish the current waveform calculated in this application from the current waveform obtained from simulation. This demonstrates that this application possesses high solution accuracy, and for the analysis needs of power distribution networks, the minor errors between the actual waveform and the calculated waveform are negligible.

[0083] In summary, the instantaneous current calculation method for a series-parallel hybrid transformer based on thyristor control in this application solves the instantaneous current value of the TCHT based on the thyristor conduction state. It fully analyzes the TCHT topology and control principle, establishes an instantaneous current value model for the TCHT under different thyristor conduction states, and uses the voltage values ​​across the TCHT obtained from power flow calculations to solve for the instantaneous current flowing through the TCHT. Therefore, the instantaneous current value model of the TCHT constructed by this method has high solution accuracy, meets the analysis needs of distribution networks, and has a fast solution speed and wide applicability. It can effectively improve the dynamic analysis capability of distribution networks, effectively support the optimization of current-based protection mechanisms in distribution networks, and by accurately solving the instantaneous current value of the TCHT, it is beneficial to identify fault points in the distribution network, improve the timeliness and effectiveness of fault handling, reduce the harm caused by faults, and improve the stability and reliability of the distribution network.

[0084] To more clearly illustrate the practical application of the TCHT current instantaneous value calculation method of this application, the following specific embodiment in a real-time application is used to describe the solution process. For example... Figure 5 As shown, in this embodiment, electromagnetic transient simulation is first performed on a medium-voltage distribution network containing a novel series-parallel flexible interconnection device (TCHT) to obtain instantaneous current data and thyristor conduction states during power flow regulation between different distribution areas. Then, steady-state voltage values ​​are calculated based on steady-state modeling, generating corresponding instantaneous voltage waveforms. During the solution process, taking phase A in a three-phase symmetrical structure as an example, circuit parameters are adjusted according to different thyristor conduction states. Combined with the calculated voltage across the TCHT, the parameters are substituted into the instantaneous current value calculation formula, and the Runge-Kutta method is used to initially calculate the instantaneous current value. Then, to ensure the safety of the TCHT during state switching, the current waveform is corrected. The zero-crossing point of the current is accurately obtained using a sine wave fitting method, and the thyristor state is accurately switched at the zero-crossing point, thus obtaining the accurate current waveform flowing through the TCHT. This method is applicable to the instantaneous value calculation of series-parallel flexible interconnection devices (TCHT) and has the advantages of high accuracy, fast solution, and wide applicability.

[0085] To achieve the above embodiments, this application also proposes a system for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control. Figure 6 This is a schematic diagram of a system for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control, as proposed in an embodiment of this application. Figure 6 As shown, the system includes: simulation module 100, modification module 200, calculation module 300 and correction module 400.

[0086] The simulation module 100 is used to perform electromagnetic transient simulation on a distribution network equipped with a thyristor-controlled series-parallel hybrid transformer (TCHT) through a simulation application, obtain the conduction state of the thyristor when the TCHT performs power flow regulation between different distribution areas, and determine the instantaneous voltage waveform based on the conduction state of the thyristor.

[0087] Modification module 200 is used to modify multiple parameters in each phase circuit of the TCHT by means of the conduction state of the thyristors. These multiple parameters include the equivalent leakage inductance and voltage value of each winding subarray connected to the secondary circuit.

[0088] The calculation module 300 is used to model the instantaneous value of the current flowing through the TCHT to obtain the instantaneous current value equation, and to substitute the instantaneous voltage value waveform and the modified multiple parameters into the instantaneous current value equation to calculate the initial instantaneous current value.

[0089] The correction module 400 is used to correct the initial instantaneous current value based on the TCHT state switching protection requirements to obtain the waveform of the instantaneous current flowing through the TCHT.

[0090] Optionally, in one embodiment of this application, the simulation module 100 is specifically used for: performing steady-state modeling on the power distribution network simulation model; calculating the steady-state voltage value across the TCHT in each conduction state based on the obtained steady-state model and the conduction state of the thyristor; converting the steady-state voltage value into an instantaneous voltage value and determining the instantaneous voltage value expression; and generating an instantaneous voltage value waveform based on the instantaneous voltage value expression.

[0091] Optionally, in one embodiment of this application, the correction module 400 is specifically used to: determine the current zero-crossing moment by fitting each initial instantaneous current value with a sine wave; and switch the thyristor conduction state at the current zero-crossing moment to determine the waveform of the instantaneous current flowing through the TCHT after the state switching adjustment.

[0092] It should be noted that the explanation of the aforementioned embodiment of the method for solving the instantaneous value of the current of a series-parallel hybrid transformer based on thyristor control is also applicable to the system of this embodiment, and the implementation principle is the same, so it will not be repeated here.

[0093] In summary, the thyristor-controlled series-parallel hybrid transformer current instantaneous value solution system of this application solves the TCHT current instantaneous value based on the thyristor conduction state. It fully analyzes the TCHT topology and control principle, establishes TCHT instantaneous value models under different thyristor conduction states, and uses the voltage values ​​across the TCHT obtained from power flow calculations to solve for the instantaneous current flowing through the TCHT. Therefore, the TCHT instantaneous value model constructed by this system has high solution accuracy, can meet the analysis needs of distribution networks, and has a fast solution speed and wide applicability, effectively improving the dynamic analysis capabilities of distribution networks.

[0094] To implement the above embodiments, this application also proposes a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the method for solving the instantaneous value of the current of a series-parallel hybrid transformer based on thyristor control as described in any one of the first aspect embodiments above.

[0095] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0096] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0097] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0098] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0099] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0100] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0101] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0102] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for solving the instantaneous value of current in a series-parallel hybrid transformer based on thyristor control, characterized in that, Includes the following steps: Electromagnetic transient simulation was performed on a distribution network equipped with a thyristor-controlled series-parallel hybrid transformer (TCHT) using simulation applications. The conduction state of the thyristor was obtained when the TCHT regulated the power flow between different distribution areas, and the instantaneous voltage waveform was determined based on the conduction state of the thyristor. For each phase circuit in the TCHT, multiple parameters in the circuit are modified by the conduction state of the thyristor, wherein the multiple parameters include the equivalent leakage inductance and voltage value of each winding subarray connected to the secondary circuit. The instantaneous value model of the current flowing through the TCHT is performed to obtain the instantaneous current value equation, and the instantaneous voltage waveform and the modified multiple parameters are substituted into the instantaneous current value equation to calculate the initial instantaneous current value; The initial instantaneous current value is corrected based on the state switching protection requirements of the TCHT to obtain the waveform of the instantaneous current flowing through the TCHT.

2. The method according to claim 1, characterized in that, The determination of the instantaneous voltage waveform based on the conduction state of the thyristor includes: Steady-state modeling is performed on the power distribution network simulation model. Based on the obtained steady-state model and the conduction state of the thyristor, the steady-state voltage value across the TCHT is calculated in each conduction state. The steady-state voltage value is converted into an instantaneous voltage value, and the instantaneous voltage value expression is determined. The instantaneous voltage value waveform is then generated based on the instantaneous voltage value expression.

3. The method according to claim 1, characterized in that, The equivalent leakage inductance is calculated using the following formula: L eq =aa*L1+bb*L1+cc*L1; The voltage value is calculated using the following formula: Among them, u Aa u Ba and u Ca These represent the voltage outputs of the three-phase winding subarray, where (a, b, c) are the voltage coordinates corresponding to the three-phase winding subarray. The conduction state of the thyristor is represented by the coordinates (a, b, c), n T This represents the turns ratio of the parallel transformer, L1 is the equivalent leakage inductance of the first secondary winding of the parallel transformer, (aa, bb, cc) are the coefficients obtained by decoding the voltage coordinates (a, b, c), and u 1A u 1B and u 1C These are the voltages on the primary side of a three-phase parallel transformer.

4. The method according to claim 3, characterized in that, The instantaneous current equation is expressed by the following formula: Where, n a It is the turns ratio of a series transformer, L T It is the equivalent leakage inductance of the series transformer, i is the current flowing through the TCHT, and u is the equivalent leakage inductance of the series transformer. 1A and u 2A It is the voltage across the TCHT, R eq It is the equivalent resistance of each winding subarray; The calculation of the initial instantaneous current value includes: The instantaneous current equation after substituting the parameters was solved using the fourth-order Runge-Kutta method.

5. The method according to claim 1, characterized in that, The initial instantaneous current value is corrected based on the state switching protection requirements of the TCHT, including: The moment when the current crosses zero is determined by fitting each of the instantaneous values ​​of the initial current with a sine wave. The thyristor conduction state is switched at the moment the current crosses zero, and the instantaneous waveform of the current flowing through the TCHT after the state switch adjustment is determined.

6. The method according to any one of claims 1 to 5, characterized in that, The TCHT includes: a parallel excitation section, a thyristor-controlled valve-controlled voltage combination section, and a series voltage compensation section; wherein, The parallel excitation section includes three single-phase multi-winding transformers. The primary side of each transformer is connected in parallel to the distribution network system to obtain the system voltage, and the secondary side of each transformer corresponds to three winding subarrays.

7. A system for solving the instantaneous current value of a series-parallel hybrid transformer based on thyristor control, characterized in that, include: The simulation module is used to perform electromagnetic transient simulation on a distribution network equipped with a thyristor-controlled series-parallel hybrid transformer (TCHT) through a simulation application, obtain the conduction state of the thyristor when the TCHT performs power flow regulation between different distribution areas, and determine the instantaneous voltage waveform based on the conduction state of the thyristor. The modification module is used to modify multiple parameters in each phase circuit of the TCHT by means of the conduction state of the thyristor, wherein the multiple parameters include the equivalent leakage inductance and voltage value of each winding subarray connected to the secondary circuit. The calculation module is used to model the instantaneous value of the current flowing through the TCHT to obtain the instantaneous current value equation, and to substitute the instantaneous voltage waveform and the modified multiple parameters into the instantaneous current value equation to calculate the initial instantaneous current value; The correction module is used to correct the initial instantaneous current value based on the state switching protection requirements of the TCHT to obtain the waveform of the instantaneous current flowing through the TCHT.

8. The system according to claim 7, characterized in that, The simulation module is specifically used for: Steady-state modeling is performed on the power distribution network simulation model. Based on the obtained steady-state model and the conduction state of the thyristor, the steady-state voltage value across the TCHT is calculated in each conduction state. The steady-state voltage value is converted into an instantaneous voltage value, and the instantaneous voltage value expression is determined. The instantaneous voltage value waveform is then generated based on the instantaneous voltage value expression.

9. The system according to claim 7, characterized in that, The correction module is specifically used for: The moment when the current crosses zero is determined by fitting each of the instantaneous values ​​of the initial current with a sine wave. The thyristor conduction state is switched at the moment the current crosses zero, and the instantaneous waveform of the current flowing through the TCHT after the state switch adjustment is determined.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the method for solving the instantaneous value of the current of a series-parallel hybrid transformer based on thyristor control as described in any one of claims 1-6.

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