Series-parallel hybrid transformer current instantaneous value solving method based on thyristor control

Abstract

The invention provides a series-parallel hybrid transformer current instantaneous value solving method based on thyristor control, and the method comprises the steps: carrying out the simulation of a power distribution network equipped with a TCHT through a simulation application, obtaining the conduction state of a thyristor during the operation of the TCHT, and determining a voltage instantaneous value waveform based on the conduction state of the thyristor; for each phase of circuit in the TCHT, modifying a plurality of parameters in the circuit through the conduction state of a thyristor; instantaneous value modeling is carried out on the current flowing through the TCHT to obtain a current instantaneous value equation, the voltage instantaneous value waveform and the modified parameters are substituted into the equation, and an initial current instantaneous value is solved; and correcting the initial current instantaneous value based on the state switching protection requirement of the TCHT to obtain the waveform of the current instantaneous value flowing through the TCHT. According to the method, the instantaneous value of the current flowing through the TCHT can be accurately solved by establishing the TCHT instantaneous value model under different thyristor conduction states, and the accuracy, convenience and applicability of calculation of the instantaneous value of the current of the TCHT are improved.

Description

Technical Field

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

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

[0003] Among them, the specific manifestations of the above traditional modes not adapting to current needs include: bidirectional flow of power flow, overload of some line capacity, node voltage exceeding the limit, frequent and drastic load fluctuations, and blurred source-load boundaries. The root cause of the above problems lies in the low reliable power supply capacity of the distribution network under the traditional open-loop operation mode. Therefore, realizing the interconnected operation of the distribution network is an effective means to solve these problems. Flexible interconnection technology can not only realize the interconnection and transfer of distribution networks, but also has the function of power flow regulation. Therefore, the key equipment and technologies for flexible interconnection of distribution networks have gradually received attention, and flexible interconnected distribution networks have also become an important direction for the development of distribution networks.

[0004] In the related art, in order to meet the actual application needs, the thyristor controlled series-parallel hybrid transformer (TCHT) based on thyristor control is gradually promoted and applied in the distribution network. However, since the TCHT involves the control of thyristors and the change of the switching state during operation, the nonlinearity of the distribution network operation characteristics is enhanced. The research on flexible interconnection equipment in the related art mainly focuses on the topology and steady-state model of flexible interconnection equipment. The important instantaneous electrical quantities after the TCHT is connected to the distribution network cannot be directly calculated, which is not conducive to analyzing its dynamic characteristics in the distribution network.

[0005] Therefore, how to accurately solve the instantaneous value of current during the operation of TCHT after it is connected to the distribution network has become an urgent problem to be solved. Summary of the invention

[0006] The present application aims to solve one of the technical problems in the related art at least to some extent.

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

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

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

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

[0011] Perform electromagnetic transient simulation on the distribution network equipped with the series-parallel hybrid transformer TCHT based on thyristor control through simulation applications, obtain the conduction states of the thyristors when the TCHT performs power flow regulation between different distribution regions, and determine the voltage instantaneous value waveform based on the conduction states of the thyristors;

[0012] For each phase circuit in the TCHT, modify multiple parameters in the circuit through the conduction states of the thyristors, where the multiple parameters include the equivalent leakage inductance and voltage values of each winding subarray connected to the secondary side circuit;

[0013] Perform instantaneous value modeling on the current flowing through the TCHT to obtain an instantaneous value equation of the current, and substitute the voltage instantaneous value waveform and the modified multiple parameters into the instantaneous value equation of the current to calculate the initial instantaneous value of the current;

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

[0015] Optionally, in an embodiment of this application, determining the voltage instantaneous value waveform based on the conduction states of the thyristors includes: performing steady-state modeling on the distribution network simulation model, calculating the voltage steady-state value at both ends of the TCHT in each conduction state according to the obtained steady-state model and the conduction states of the thyristors; converting the voltage steady-state value into a voltage instantaneous value and determining the voltage instantaneous value expression, and generating the voltage instantaneous value waveform according to the voltage instantaneous value expression.

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

[0017] L eq = aa * L 1 + bb * L 1 + cc * L 1 ;

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

[0019]

[0020] where u Aa , u Ba and u Ca are the voltages output by the three-phase winding sub-array respectively, (a, b, c) are the voltage coordinates corresponding to the three-phase winding sub-array, the conduction state of the thyristor is represented by the coordinates (a, b, c), n T is the turns ratio of the parallel transformer, L 1 is the equivalent leakage inductance of the first secondary winding of the parallel transformer, (aa, bb, cc) are the coefficients decoded from the voltage coordinates (a, b, c), u 1A , u 1B and u 1C are the voltages of the primary side of the three-phase parallel transformer respectively.

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

[0022]

[0023] where n a is the turns ratio of the series transformer, L T is the equivalent leakage inductance of the series transformer, i is the current flowing through the TCHT, u 1A and u 2A are the voltages across the TCHT, R eq is the equivalent resistance of each winding sub-array;

[0024] Calculating the initial instantaneous current value includes: solving the instantaneous current value equation after substituting parameters by the fourth-order Runge-Kutta method.

[0025] Optionally, in an embodiment of the present application, modifying the initial instantaneous current value based on the state switching protection requirement of the TCHT includes: performing sine wave fitting on each of the initial instantaneous current values to determine the current zero-crossing moment; switching the conduction state of the thyristor at the current zero-crossing moment to determine the waveform of the instantaneous current value flowing through the TCHT after state switching adjustment.

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

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

[0028] A simulation module, configured to perform an electromagnetic transient simulation on a distribution network equipped with a series-parallel hybrid transformer TCHT based on thyristor control through a simulation application, obtain the conduction state of the thyristor when the TCHT performs power flow regulation between different distribution regions, and determine the voltage instantaneous value waveform based on the conduction state of the thyristor;

[0029] A modification module, configured to modify multiple parameters in the circuit for each phase circuit of the TCHT through the conduction state of the thyristor, wherein the multiple parameters include the equivalent leakage inductance and voltage value of each winding sub-array connected to the secondary side circuit;

[0030] A calculation module, configured to perform an instantaneous value modeling on the current flowing through the TCHT to obtain an instantaneous value equation of the current, and substitute the voltage instantaneous value waveform and the modified multiple parameters into the instantaneous value equation of the current to calculate the initial current instantaneous value;

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

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

[0033] The technical solutions provided by the embodiments of the present application at least bring the following beneficial effects: Based on the conduction state of thyristors, the present application solves the instantaneous value of the TCHT current, fully analyzes the topology and control principle of TCHT, establishes an instantaneous value model of TCHT under different thyristor conduction states, and uses the voltage value at both ends of TCHT obtained by power flow calculation to solve the instantaneous value of the current flowing through TCHT. Therefore, the instantaneous value model of TCHT constructed in the present application has high solution accuracy, can meet the analysis requirements of the distribution network, and has a fast solution speed and wide applicability. It can effectively improve the dynamic analysis ability of the distribution network, effectively support the optimization of the protection mechanism mainly based on current protection in the distribution network. By accurately solving the instantaneous value of the TCHT current, it is beneficial to identify the fault points in the distribution network, improve the timeliness and effectiveness of fault handling, reduce the harm caused by faults, and is beneficial to improving the stability and reliability of the distribution network.

[0034] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0036] Figure 1 is a flowchart of a method for solving the instantaneous value of the current of a series-parallel hybrid transformer based on thyristor control proposed by an embodiment of the present application;

[0037] Figure 2 is a schematic topological diagram of a series-parallel hybrid transformer based on thyristor control proposed by an embodiment of the present application;

[0038] Figure 3 is a schematic diagram of a medium-voltage distribution network simulation model equipped with TCHT proposed by an embodiment of the present application;

[0039] Figure 4 is a schematic diagram of the comparison between the simulated current waveform and the waveform obtained by solving the instantaneous value proposed by an embodiment of the present application;

[0040] Figure 5 is a schematic diagram of the principle of a specific process for solving the instantaneous value of the TCHT current proposed by an embodiment of the present application;

[0041] Figure 6 is a schematic structural diagram of a system for solving the instantaneous value of the current of a series-parallel hybrid transformer based on thyristor control proposed by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where 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 are intended to explain the present invention and should not be construed as limiting the present invention.

[0043] It should be noted that the current key equipment for flexible interconnection for distribution networks in related embodiments can no longer meet the application requirements of distribution networks. For example, a phase shifting transformer (PST) is a typical electromagnetic flexible interconnection equipment. However, such equipment uses mechanical switches with slow response speed and short lifespan to adjust the magnitude of the compensated voltage, and has disadvantages such as long response time and complex operation and maintenance. With the development of power electronics technology, fully power electronic flexible interconnection equipment represented by the unified power flow controller (UPFC) has been widely applied, but problems such as its high cost, large volume, and difficult operation and maintenance have restricted its popularization and application in distribution networks.

[0044] To meet the actual needs, based on semi-controlled power electronic devices and the "Sen" transformer, this application proposes a new type of series-parallel flexible interconnection equipment, namely a thyristor controlled hybrid transformer (TCHT). TCHT has a larger compensation range and can quickly achieve cross-level voltage regulation, which is beneficial to the interconnection and transfer power supply of the distribution network.

[0045] However, since the control of thyristors and the change of switch states are involved in the operation of TCHT, its corresponding circuit is a typical time-varying circuit, resulting in an enhanced non-linearity of the operating characteristics of the distribution network. Especially when the system is disturbed, it is difficult to analytically express the electrical quantities of TCHT and the distribution network, and important instantaneous electrical quantities cannot be directly calculated. Existing research mainly focuses on the topology and steady-state model of flexible interconnection equipment, and relatively few studies have been conducted on the transient model analysis after its access to the distribution network.

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

[0047] A method and system for solving the instantaneous value of the current of a thyristor controlled hybrid transformer proposed in the embodiments of the present invention will be described below with reference to the accompanying drawings.

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

[0049] Step S101: Conduct electromagnetic transient simulation on the distribution network equipped with the series - parallel hybrid transformer TCHT based on thyristor control through simulation application, obtain the conduction state of the thyristors when TCHT performs power flow regulation between different distribution regions, and determine the instantaneous voltage value waveform based on the conduction state of the thyristors.

[0050] Specifically, in this step, first use simulation software to perform simulation modeling on the distribution network containing TCHT to calculate instantaneous voltage data. To more clearly illustrate the principle of solving the instantaneous value of the TCHT current in the present application, the topological structure of the novel series - parallel flexible interconnection equipment TCHT targeted by the present application will be described first.

[0051] In an embodiment of the present application, TCHT includes: a shunt excitation part, a thyristor - controlled valve - controlled voltage combination part, and a series voltage compensation part. Among them, the shunt excitation part includes three single - phase multi - winding transformers. The primary side of each transformer is shunt - connected to the distribution network system to obtain the system voltage, and the secondary side of each transformer corresponds to three winding sub - arrays.

[0052] Specifically, in this embodiment, as Figure 2 shown, the TCHT circuit is a series - parallel structure. Figure 2 In it, the main three parts are divided by a dotted line box: the shunt excitation part, the thyristor - controlled valve - controlled voltage combination part, and the series voltage compensation part, and different phases of TCHT are distinguished by different colors. Among them, the shunt excitation part uses three single - phase multi - winding transformers. The primary side is shunt - connected to the distribution network system to obtain the system voltage. Each secondary side corresponds to three sub - winding arrays (which can be simply referred to as winding sub - arrays in the present application). In this embodiment, a model is established with the number of turns of the secondary winding of the shunt transformer being 2 and the rated voltage ratio being 1:3 as an example.

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

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

[0055] Table 1 Specific parameter table of the simulation model

[0056]

[0057] Further, according to the obtained simulation model and the obtained thyristor conduction state, the instantaneous voltage waveform of TCHT is obtained.

[0058] In an embodiment of the present application, determining the instantaneous voltage waveform based on the thyristor conduction state includes: performing steady-state modeling on the distribution network simulation model, and calculating the steady-state voltage value at both ends of TCHT in each conduction state according to the obtained steady-state model and the thyristor conduction state; converting the steady-state voltage value into an instantaneous voltage value and determining the instantaneous voltage value expression, and generating the instantaneous voltage value waveform according to the instantaneous voltage value expression.

[0059] Specifically, in this embodiment, for the steady-state modeling of the distribution network containing TCHT, steady-state modeling can be further performed on the basis of the existing simulation model, and then according to the thyristor conduction state corresponding to the simulation and the steady-state model, the steady-state voltage value at both ends of TCHT during power flow regulation in each conduction state is calculated. Then, the waveform of the corresponding instantaneous voltage value is drawn through the obtained steady-state voltage value. For example, each steady-state voltage value is converted into an instantaneous value, the instantaneous voltage value expression is summarized, and then the voltage waveform is drawn according to the instantaneous voltage value expression.

[0060] Step S102, for each phase circuit in TCHT, modify multiple parameters in the circuit through the thyristor conduction state, where the multiple parameters include the equivalent leakage inductance and voltage value of each winding sub-array connected to the secondary side loop.

[0061] It should be noted that since TCHT has a three-phase symmetrical structure, the three phases can be reduced to one phase for solution, and the solution method for each phase is the same. Therefore, in this application, one phase, such as phase A, is taken as an example to solve the instantaneous current value, and the solution processes of other phases are the same, which will not be elaborated in this application.

[0062] Specifically, since different thyristor conduction states will change the operating state of the circuit, it is necessary to modify the parameters in the circuit according to the thyristor conduction state corresponding to the simulation.

[0063] In an embodiment of the present application, the equivalent leakage inductance is calculated by the following formula:

[0064] L eq =aa*L 1 +bb*L 1 +cc*L 1 ;

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

[0066]

[0067] Among them, u Aa 、u Ba and u Ca are the voltages output by the three-phase winding sub-array respectively, (a, b, c) are the voltage coordinates corresponding to the three-phase winding sub-array, and the conduction states of the thyristors are represented by the coordinates (a, b, c), n T is the turns ratio of the parallel transformer, L 1 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), u 1A 、u 1B and u 1C are the voltages of the primary side of the three-phase parallel transformer respectively.

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

[0069] Among them, the parameters aa, bb, and cc in the above formulas have a corresponding relationship with the coordinates (a, b, c), and the relevant values can be determined with reference to Table 2 below.

[0070] Table 2 Parameter correspondence table

[0071]

[0072] Step S103, perform instantaneous value modeling on the current flowing through the TCHT to obtain the current instantaneous value equation, and substitute the voltage instantaneous value waveform and the modified multiple parameters into the current instantaneous value equation to calculate the initial current instantaneous value.

[0073] Specifically, perform instantaneous value modeling on the current flowing through the TCHT to obtain the current instantaneous value equation, and then substitute the voltage instantaneous value waveform obtained in step S101 and the respective parameters calculated in step S102 into the current instantaneous value equation, and use the relevant calculation method to solve the current flowing through the TCHT.

[0074] In an embodiment of the present application, the current instantaneous value equation is represented by the following formula:

[0075]

[0076] Among them, n a is the turns ratio of the series transformer, L T is the equivalent leakage inductance of the series transformer, i is the current flowing through the TCHT, u1A and u 2A is the voltage across TCHT. Since the embodiments of this application solve the problem taking Phase A as an example, the voltage u of the primary side of Phase A is used here 1A and the voltage u of the secondary side 2A for calculation, and R eq is the equivalent resistance of each winding subarray.

[0077] In this embodiment, the equivalent leakage inductance L eq calculated in step S102 and the voltage value u eq are substituted into the above equation, and the voltage u 1A across TCHT calculated in step S101 and u 2A are substituted into the above equation. Then, the fourth-order Runge-Kutta method is used to solve the equation after substituting the parameters, and the current flowing through TCHT is initially calculated, that is, the initial current instantaneous value is solved.

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

[0079] Specifically, when the thyristor in TCHT switches states, to avoid the phenomenon of short circuit in the winding, it is necessary to ensure that all thyristors in the previous state are reliably turned off before the trigger signal of the thyristor in the next state can be sent out. And the moment when the thyristor is turned off should be when the current passes through zero and the reverse voltage lasts for a period of time. Therefore, it is necessary to correct the current instantaneous value obtained in step S103 to obtain the final waveform of the current instantaneous value of TCHT.

[0080] In an embodiment of this application, correcting the initial current instantaneous value based on the state switching protection requirements of TCHT includes: determining the current zero-crossing moment by fitting each initial current instantaneous value with a sine wave; switching the conduction state of the thyristor at the current zero-crossing moment to determine the waveform of the current instantaneous value flowing through TCHT after the state switching adjustment.

[0081] Specifically, in this embodiment, since the thyristor needs to wait until the current passes through zero and maintains a certain reverse voltage to be reliably turned off, each state current instantaneous value obtained in step S103 is fitted with a sine wave, and the time point when the current passes through zero is accurately obtained by the sine wave fitting method. Then, the conduction state of the thyristor is switched at the current zero-crossing moment, and finally the corrected current instantaneous value waveform is obtained. Among them, the correction process can be to adjust the waveform according to the actual conduction state switching, re-determine the conduction state of the thyristor according to the state switching requirements, and adjust the TCHT instantaneous value model established in the above embodiments under different thyristor conduction states, etc.

[0082] To more fully illustrate the solution result of the instantaneous current value of the present application, as an example, for phase A of TCHT, the current waveform calculated according to the method for solving the instantaneous current value of the present application is compared with the thyristor simulation current obtained through simulation in step S101. The comparison result is as Figure 4 shown, Figure 4 wherein different colors are used to distinguish the current waveform calculated by the present application from the current waveform obtained through simulation. It can be seen that the present application has a high solution accuracy, and for the analysis requirements of the distribution network, the small error from the actual situation can be ignored.

[0083] In summary, the method for solving the instantaneous current value of the series-parallel hybrid transformer based on thyristor control in the embodiment of the present application solves the instantaneous current value of TCHT 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 at both ends of TCHT obtained by power flow calculation to solve the instantaneous current value flowing through TCHT. Thus, the instantaneous value model of TCHT constructed by this method has a high solution accuracy, can meet the analysis requirements of the distribution network, has a fast solution speed and wide applicability, can effectively improve the dynamic analysis ability of the distribution network, effectively support the optimization of the protection mechanism mainly based on current protection in the distribution network, and is beneficial to identifying the fault point in the distribution network, improving the timeliness and effectiveness of fault handling, reducing the harm caused by the fault, and is beneficial to improving the stability and reliability of the distribution network.

[0084] To more clearly illustrate the actual application process of the method for solving the instantaneous current value of TCHT of the present application, the following uses a specific embodiment in real-time application to illustrate the solution process. As Figure 5 shown, in this embodiment, first, an electromagnetic transient simulation is performed on the medium-voltage distribution network containing the new series-parallel flexible interconnection equipment TCHT to obtain the instantaneous current value data of TCHT during power flow regulation between different distribution regions and the conduction state of the thyristor. Then, the steady-state voltage value is calculated based on steady-state modeling to generate the corresponding instantaneous voltage waveform. During the solution process, taking phase A in the three-phase symmetrical structure as an example, the circuit parameters are adjusted according to different thyristor conduction states, and combined with the calculated voltage at both ends of TCHT, the parameters are substituted into the formula for solving the instantaneous current value, and the instantaneous current value is initially calculated by the Runge-Kutta method. Then, to ensure the safety of TCHT during state switching, the current waveform is corrected, the zero-crossing point of the current is accurately obtained by the method of sine wave fitting, and the thyristor state is accurately switched at the zero-crossing point of the current, so as to obtain the accurate current waveform flowing through TCHT. This method is applicable to the solution of the instantaneous value of the series-parallel flexible interconnection equipment TCHT, and has the advantages of high precision, fast solution and wide applicability.

[0085] To implement the above embodiments, the present application also proposes an instantaneous current value solving system for a series-parallel hybrid transformer controlled by thyristors. Figure 6 As shown in Figure 6 , which is a schematic structural diagram of an instantaneous current value solving system for a series-parallel hybrid transformer controlled by thyristors proposed in an embodiment of the present application. Figure 6 The system includes: a simulation module 100, a modification module 200, a calculation module 300, and a correction module 400.

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

[0087] The modification module 200 is used to modify multiple parameters in each phase circuit of the TCHT according to the conduction state of the thyristors. Among them, the multiple parameters include the equivalent leakage inductance and voltage value of each winding subarray connected to the secondary side circuit.

[0088] The calculation module 300 is used to perform instantaneous value modeling on the current flowing through the TCHT to obtain an instantaneous current value equation, and substitute the voltage instantaneous 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 state switching protection requirements of the TCHT to obtain the instantaneous current value waveform of the current flowing through the TCHT.

[0090] Optionally, in an embodiment of the present application, the simulation module 100 is specifically used for: performing steady-state modeling on the distribution network simulation model, calculating the voltage steady-state value at both ends of the TCHT in each conduction state according to the obtained steady-state model and the conduction state of the thyristors; converting the voltage steady-state value into a voltage instantaneous value and determining the voltage instantaneous value expression, and generating a voltage instantaneous value waveform according to the voltage instantaneous value expression.

[0091] Optionally, in an embodiment of the present application, the correction module 400 is specifically used for: determining the current zero-crossing moment by performing sine wave fitting on each initial instantaneous current value; switching the conduction state of the thyristors at the current zero-crossing moment to determine the instantaneous current value waveform of the current flowing through the TCHT after state switching adjustment.

[0092] It should be noted that the foregoing explanation of the embodiments of the instantaneous current value solving method for the series-parallel hybrid transformer controlled by thyristors also applies to the system of this embodiment, and the implementation principles are the same, so they will not be elaborated here.

[0093] In summary, the instantaneous current value solving system of the series-parallel hybrid transformer based on thyristor control according to the embodiments of the present application solves the instantaneous current value of the TCHT based on the thyristor conduction state, fully analyzes the topology and control principle of the TCHT, establishes an instantaneous value model of the TCHT under different thyristor conduction states, and uses the voltage value at both ends of the TCHT obtained by power flow calculation to solve the instantaneous current value of the current flowing through the TCHT. Therefore, the instantaneous value model of the TCHT constructed by this system has high solving accuracy, can meet the analysis requirements of the distribution network, and has a fast solving speed and wide applicability, and can effectively improve the dynamic analysis ability of the distribution network.

[0094] To implement the above embodiments, the present application also proposes a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the method for solving the instantaneous current value of the series-parallel hybrid transformer based on thyristor control according to any one of the above first aspect embodiments.

[0095] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without conflict, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0096] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of these features. In the description of the present application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0097] Any process or method description shown in a flowchart or described in other ways herein can be understood as representing a module, segment, or part of code including one or more executable instructions for implementing a customized logic function or process. The scope of the preferred embodiments of the present application includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in a reverse order according to the involved functions, rather than in the order shown or discussed, which should be understood by those skilled in the art in the technical field to which the embodiments of the present application belong.

[0098] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a definable sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or used in combination with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: electrical connection parts with one or more wirings (electronic devices), portable computer disk cartridges (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or other suitable processing as necessary, and then stored in a computer memory.

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

[0100] Those of ordinary skill in the art of this technology can understand that all or part of the steps carried by the method of implementing the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0101] In addition, each functional unit in various embodiments of the present application may be integrated into one processing module, may exist physically alone for each unit, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

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

Claims

1. A method for solving the instantaneous value of current of a series-parallel hybrid transformer based on thyristor control, characterized in that: The following steps are involved: Through the simulation application, an electromagnetic transient simulation is performed on the distribution network equipped with a series-parallel hybrid transformer TCHT based on thyristor control, the conduction state of the thyristor is obtained when the TCHT performs power flow regulation between different distribution areas, and the voltage instantaneous value waveform is 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 equivalent leakage inductance and voltage value of each winding subarray connected to the secondary loop; Performing instantaneous value modeling on the current flowing through the TCHT to obtain an instantaneous value equation of the current, and substituting the instantaneous value waveform of the voltage and the modified multiple parameters into the instantaneous value equation of the current to calculate an initial instantaneous value of the current; The initial current instantaneous value is corrected based on the state switching protection requirement of the TCHT to obtain an instantaneous value waveform of the current flowing through the TCHT.

2. The method according to claim 1, characterized in that The step of determining a voltage instantaneous value waveform based on the conduction state of the thyristor comprises: Performing steady-state modeling on the distribution network simulation model, and calculating the steady-state value of the voltage across the TCHT in each conduction state according to the obtained steady-state model and the conduction state of the thyristor; The voltage steady-state value is converted into a voltage instantaneous value and an expression of the voltage instantaneous value is determined, and the voltage instantaneous value waveform is generated according to the voltage instantaneous value expression.

3. The method according to claim 1, characterized in that The equivalent leakage inductance is calculated by the following formula: L eq =aa*L1+bb*L1+cc*L1; The voltage value is calculated by the following formula: Among them, u Aa 、u Ba and u Ca are the voltages output by the three-phase winding sub-arrays, (a, b, c) are the voltage coordinates corresponding to the three-phase winding sub-arrays, the conduction state of the thyristor is represented by the coordinates (a, b, c), n T is the transformation ratio of the shunt transformer, L1 is the equivalent leakage inductance of the first secondary winding of the shunt transformer, (aa, bb, cc) are the coefficients obtained by decoding the voltage coordinates (a, b, c), and u 1A 、u 1B and u 1C They are the primary voltages of the three-phase parallel transformers.

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

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

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

7. A system for solving the instantaneous value of current of a series-parallel hybrid transformer based on thyristor control, characterized in that: include: A simulation module, used to perform electromagnetic transient simulation on a distribution network equipped with a series-parallel hybrid transformer TCHT based on thyristor control 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 voltage instantaneous value waveform based on the conduction state of the thyristor; A modification module, configured to modify, for each phase circuit in the TCHT, a plurality of parameters in the circuit by the conduction state of the thyristor, wherein the plurality of parameters include an equivalent leakage inductance and a voltage value of each winding subarray connected to the secondary loop; A calculation module, configured to perform instantaneous value modeling on the current flowing through the TCHT to obtain an instantaneous value equation of the current, and substitute the instantaneous value waveform of the voltage and the modified multiple parameters into the instantaneous value equation of the current to calculate an initial instantaneous value of the current; The correction module is used to correct the initial current instantaneous value based on the state switching protection requirement of the TCHT to obtain the instantaneous value waveform of the current flowing through the TCHT.

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

9. The system according to claim 7, characterized in that The correction module is specifically used for: Determine the current zero-crossing moment by performing sine wave fitting on each of the instantaneous values ​​of the initial current; The conduction state of the thyristor is switched at the current zero-crossing moment, and the instantaneous value waveform of the current flowing through the TCHT after the state switching 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 a processor, the method for solving the instantaneous value of current of a series-parallel hybrid transformer based on thyristor control as described in any one of claims 1 to 6 is implemented.

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