CN115964980A - Equivalent calculation method for transformer wave process - Google Patents
Equivalent calculation method for transformer wave process Download PDFInfo
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- CN115964980A CN115964980A CN202310014313.1A CN202310014313A CN115964980A CN 115964980 A CN115964980 A CN 115964980A CN 202310014313 A CN202310014313 A CN 202310014313A CN 115964980 A CN115964980 A CN 115964980A
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Abstract
The application provides a transformer wave process equivalent calculation method. The method comprises the following steps: respectively building a transformer distribution parameter equivalent circuit and a reactor distribution parameter equivalent circuit according to a wave process wiring schematic diagram of a high-impedance transformer with series impedance and winding structures of the transformer and the reactor; based on a two-port network principle, the equivalent circuit of the distribution parameters of the reactor is equivalent to an equivalent circuit of the reactor; constructing a high-impedance transformer wave process simulation model based on the transformer distribution parameter equivalent circuit and the reactor equivalent circuit, and calculating to obtain a voltage distribution parameter of the transformer based on the high-impedance transformer wave process simulation model; and calculating the voltage distribution parameters of the reactor based on the equivalent circuit of the reactor distribution parameters. The method and the device can accurately calculate the single equipment wave process distribution under the condition of multi-equipment series connection, and ensure the insulation reliability of the high-impedance transformer with the series impedance.
Description
Technical Field
The application relates to the technical field of transformers, in particular to a transformer wave process equivalent calculation method.
Background
With the rapid expansion of the grid size, the short circuit capacity increases dramatically, leading to the occurrence of short circuit current levels exceeding the breaker break capacity. Compared with the conventional transformer, the high-impedance transformer has a larger short-circuit impedance, so that the effect of limiting the short-circuit current is more obvious, and the high-impedance transformer is widely applied to a power grid.
One of the common structures of the high-impedance transformer is that the transformer and the reactor are placed in an oil tank, the bodies of the transformer and the reactor are independent, and a low-voltage winding and a series reactor are connected in the oil tank through a lead. The existing wave process calculation method cannot calculate the distribution of the wave process of multiple devices, wherein the wave process of the multiple devices comprises two or even multiple devices, only electrical connection and no magnetic circuit connection. Compared with the conventional transformer wave process, the distribution of the transformer wave process with the series reactor needs to be additionally considered by two problems: firstly, one end of the low-voltage coil cannot be grounded due to the connection of the reactor in the lightning impulse test, the transfer overvoltage induced by the terminal through the capacitor and the inductor can be higher than the insulation level of the terminal, and the main insulation and the longitudinal insulation of the low-voltage coil are greatly influenced by the transfer overvoltage. And secondly, the lightning impulse at the end of the reactor is transmitted by low voltage, the oscillation frequency may be higher than the frequency band of the lightning impulse, the amplitude may also be higher than the insulation level of the reactor, and the main and longitudinal insulation structures of the reactor are directly influenced. Therefore, how to realize the wave process equivalent calculation of a plurality of body structures by using the high-impedance transformer with the series impedance is a problem to be solved at present.
Disclosure of Invention
The application provides a transformer wave process equivalent calculation method, which aims to solve the problem that the wave process calculation of a plurality of transformer body structures cannot be realized in the prior art.
In a first aspect, the present application provides a transformer wave process equivalent calculation method, including:
respectively building a transformer distribution parameter equivalent circuit and a reactor distribution parameter equivalent circuit according to a wave process wiring schematic diagram of a high-impedance transformer with a series impedance and winding structures of the transformer and the reactor;
based on a two-port network principle, the reactor distribution parameter equivalent circuit is equivalent to a reactor equivalent circuit;
constructing a high-impedance transformer wave process simulation model based on the transformer distribution parameter equivalent circuit and the reactor equivalent circuit, and calculating to obtain voltage distribution parameters of the transformer based on the high-impedance transformer wave process simulation model, wherein the voltage distribution parameters of the transformer comprise transmission overvoltage of a low-voltage line end of the transformer;
and calculating to obtain the voltage distribution parameters of the reactor based on the reactor distribution parameter equivalent circuit.
In a possible implementation manner, the respectively constructing a transformer distributed parameter equivalent circuit and a reactor distributed parameter equivalent circuit according to a wave process wiring schematic diagram of a high-impedance transformer with a series impedance and winding structures of the transformer and the reactor includes:
establishing a wave process wiring schematic diagram of the high-impedance transformer with the series impedance according to the operation mode of the high-impedance transformer;
calculating the series capacitance, the parallel capacitance, the self inductance and the mutual inductance of the transformer according to the wave process wiring schematic diagram of the high-impedance transformer with the series impedance and the winding structure of the transformer, and constructing a transformer distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self inductance and the mutual inductance of the transformer;
calculating the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the reactor according to the wave process wiring schematic diagram of the high-impedance transformer with the series impedance and the winding structure of the reactor, and constructing a distributed parameter equivalent circuit of the reactor according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the reactor.
In a possible implementation manner, the constructing a high impedance transformer wave process simulation model based on the transformer distribution parameter equivalent circuit and the reactor equivalent circuit includes:
and connecting the equivalent circuit of the reactor in series at the tail end of the low-voltage coil of the equivalent circuit of the distribution parameters of the transformer to construct a simulation model of the wave process of the high-impedance transformer.
In a possible implementation manner, the calculating a series capacitance, a parallel capacitance, a self-inductance, and a mutual inductance of a transformer according to a wave process wiring schematic diagram of the series impedance-based high impedance transformer and a winding structure of the transformer, and constructing the transformer distributed parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self-inductance, and the mutual inductance of the transformer includes:
dividing the winding of the transformer into a plurality of units according to the wave process wiring schematic diagram of the high-impedance transformer with the series impedance and the winding structure of the transformer, calculating the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the transformer, and constructing a transformer distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the transformer.
In a possible implementation, the voltage distribution parameters of the transformer further include a voltage to ground of each cell of the transformer and a voltage between cells under the lightning surge overvoltage.
In one possible implementation, after the calculating the voltage distribution parameter of the transformer based on the high impedance transformer wave process simulation model, the method further includes:
calculating the electric field distribution from the low-voltage wire end of the transformer to the iron core according to the transmission overvoltage of the low-voltage wire end of the transformer, and taking the electric field distribution as first electric field distribution;
and evaluating the reliability of the insulation structure from the low-voltage line end of the transformer to the iron core according to the first electric field distribution.
In a possible implementation manner, the calculating the voltage distribution parameter of the reactor based on the reactor distribution parameter equivalent circuit includes:
and calculating to obtain the voltage distribution parameters of the reactor according to the equivalent circuit of the distribution parameters of the reactor and by taking the transmission overvoltage of the low-voltage line end of the transformer as excitation.
In a possible implementation manner, the calculating a series capacitance, a parallel capacitance, a self-inductance, and a mutual inductance of a reactor according to a wave process wiring schematic diagram of the series impedance high-impedance transformer and a winding structure of the reactor, and constructing the reactor distributed parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self-inductance, and the mutual inductance of the reactor includes:
dividing the winding of the reactor into a plurality of units according to the wave process wiring schematic diagram of the high-impedance transformer with the series impedance and the winding structure of the reactor, calculating the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the reactor, and constructing a reactor distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the reactor.
In one possible implementation manner, the voltage distribution parameter of the reactor includes a voltage to ground of each cell of the reactor and a voltage between the cells.
In a possible implementation manner, after the calculating the voltage distribution parameter of the reactor based on the reactor distribution parameter equivalent circuit, the method further includes:
calculating the electric field distribution from the coil of the reactor to the iron core and the oil tank according to the transmission overvoltage of the low-voltage terminal of the transformer, and taking the electric field distribution as second electric field distribution;
and evaluating the reliability of the insulation structure from the coil of the reactor to the iron core and the oil tank according to the second electric field distribution.
The method comprises the steps of respectively building a transformer distribution parameter equivalent circuit and a reactor distribution parameter equivalent circuit according to a wave process wiring schematic diagram of a high-impedance transformer with series impedance and winding structures of the transformer and a reactor; based on a two-port network principle, the equivalent circuit of the distribution parameters of the reactor is equivalent to an equivalent circuit of the reactor; constructing a high-impedance transformer wave process simulation model based on a transformer distribution parameter equivalent circuit and a reactor equivalent circuit, calculating to obtain a voltage distribution parameter of the transformer based on the high-impedance transformer wave process simulation model, and evaluating the reliability of the insulation structure of the transformer according to the voltage distribution parameter; the method and the device have the advantages that the voltage distribution parameters of the reactor are obtained through calculation based on the reactor distribution parameter equivalent circuit, the reliability of the insulation structure of the reactor can be evaluated according to the voltage distribution parameters, the single equipment wave process distribution under the condition of series connection of multiple equipment can be accurately calculated according to the winding structure of the high-impedance transformer with the series impedance, and the insulation reliability of the high-impedance transformer with the series impedance is guaranteed based on the reactor distribution parameter equivalent circuit.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a flowchart illustrating an implementation of a transformer wave process equivalent calculation method according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a high impedance transformer with a series impedance according to an embodiment of the present application;
fig. 3 is a lead-out line reference diagram of a high impedance transformer with series impedance provided by an embodiment of the present application;
fig. 4 is a schematic diagram of a wave process connection of a high-impedance transformer with series impedance according to an embodiment of the present application;
FIG. 5 is an equivalent circuit diagram of distribution parameters of a transformer according to an embodiment of the present application;
FIG. 6 is an equivalent circuit diagram of distributed parameters of a reactor provided in an embodiment of the present application;
FIG. 7 is a circuit diagram of an equivalent circuit of a reactor provided in an embodiment of the present application;
FIG. 8 is a diagram of a simulation model of a high impedance transformer wave process provided in an embodiment of the present application;
fig. 9 is a simulation model diagram of a reactor wave process provided in the embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
To make the objects, technical solutions and advantages of the present application more clear, the following description is made by way of specific embodiments with reference to the accompanying drawings.
Fig. 1 is a flowchart of an implementation of a transformer wave process equivalent calculation method provided in an embodiment of the present application, which is detailed as follows:
in S101, a transformer distribution parameter equivalent circuit and a reactor distribution parameter equivalent circuit are respectively built according to a wave process wiring schematic diagram of a high-impedance transformer with series impedance and winding structures of the transformer and the reactor.
The high-impedance transformer refers to a transformer with the short-circuit voltage percentage exceeding the percentage value specified by the national standard of the same voltage class and the same capacity. There are two schemes for implementing a high impedance transformer: firstly, the medium-voltage side winding is split into two parts to increase the leakage reactance of the winding; and secondly, the leakage reactance of the winding is increased by connecting the lead in series with the reactor at the tail end of the low-voltage winding of the transformer.
The second high-impedance transformer with the series impedance has the structure that: the transformer and the reactor are arranged in an oil tank, the transformer and the reactor are only in electrical connection without magnetic circuit connection, and the arrangement of the transformer body is shown in a reference figure 2.
The leading-out wires of the high-impedance transformer with the series impedance are shown in fig. 3, the high-voltage head end A, the tail end X and the low-voltage head end a of the transformer and the tail end X of the reactor are led out to the outside of the oil tank to be connected with a power grid system, and the low-voltage X1 end of the transformer and the X1 end of the reactor are connected into a point in the oil tank and are not led out to the outside of the oil tank.
The wave process refers to a propagation process of a voltage wave (or a current wave) on equipment in stores such as a transmission line, a cable, a transformer and a motor.
In one possible implementation, S101 may include:
establishing a wave process wiring schematic diagram of the high-impedance transformer with the series impedance according to the operation mode of the high-impedance transformer;
calculating the series capacitance, the parallel capacitance, the self inductance and the mutual inductance of the transformer according to a wave process wiring schematic diagram of a high-impedance transformer with series impedance and a winding structure of the transformer, and constructing a transformer distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self inductance and the mutual inductance of the transformer;
calculating the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the reactor according to a wave process wiring schematic diagram of the high-impedance transformer with the series impedance and a winding structure of the reactor, and constructing a reactor distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the reactor.
Referring to fig. 3 and the operation mode of the high-impedance transformer with the series impedance, a wave process wiring schematic diagram of the high-impedance transformer with the series impedance is established, referring to fig. 4, a high-voltage head end a of the transformer is used as an overvoltage inlet, and a high-voltage tail end X and a low-voltage head end a of the transformer and an X end of the reactor are grounded.
In a possible implementation manner, calculating a series capacitance, a parallel capacitance, a self-inductance, and a mutual inductance of the transformer according to a wave process wiring schematic diagram of the high-impedance transformer with the series impedance and a winding structure of the transformer, and constructing a transformer distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self-inductance, and the mutual inductance of the transformer may include:
according to a wave process wiring schematic diagram of a high-impedance transformer with series impedance and a winding structure of the transformer, a winding of the transformer is divided into a plurality of units, series capacitance, parallel capacitance, self inductance and mutual inductance of each unit of the winding of the transformer are calculated, and a transformer distribution parameter equivalent circuit is constructed according to the series capacitance, the parallel capacitance, the self inductance and the mutual inductance of each unit of the winding of the transformer.
In this embodiment, according to a winding structure of a transformer, a winding of the transformer may be divided into a plurality of units, where each unit includes a capacitor element and an inductor element, and then a series capacitance, a parallel capacitance, a self-inductance, and a mutual inductance of each unit of the winding of the transformer are calculated according to a wave process wiring schematic diagram of a high-impedance transformer with a series impedance, and a transformer distribution parameter equivalent circuit is constructed according to the calculated series capacitance, parallel capacitance, self-inductance, and mutual inductance of each unit of the winding of the transformer, and is referred to fig. 5.
In a possible implementation manner, calculating a series capacitance, a parallel capacitance, a self-inductance, and a mutual inductance of the reactor according to a wave process wiring schematic diagram of the high-impedance transformer with the series impedance and a winding structure of the reactor, and constructing a reactor distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self-inductance, and the mutual inductance of the reactor may include:
according to a wave process wiring schematic diagram of a high-impedance transformer with series impedance and a winding structure of the reactor, a winding of the reactor is divided into a plurality of units, the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the reactor are calculated, and a reactor distribution parameter equivalent circuit is constructed according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the reactor.
In the embodiment of the application, the construction process of the reactor distribution parameter equivalent circuit is consistent with that of the transformer distribution parameter equivalent circuit: first, according to a winding structure of a reactor, a winding of the reactor may be divided into a plurality of units, each unit including a capacitive element and an inductive element; then, calculating the series capacitance, the parallel capacitance, the self inductance and the mutual inductance of each unit of the winding of the reactor according to a wave process wiring schematic diagram of the high-impedance transformer with the series impedance; and finally, constructing a reactor distribution parameter equivalent circuit according to the calculated series capacitance, parallel capacitance, self inductance and mutual inductance of each unit of the winding of the reactor, wherein the reactor distribution parameter equivalent circuit refers to fig. 6.
In the embodiment of the application, the constructed transformer distribution parameter equivalent circuit and the reactor distribution parameter equivalent circuit are respectively used for calculating the overvoltage distribution condition of the transformer and the reactor.
In S102, the reactor distribution parameter equivalent circuit is equivalent to a reactor equivalent circuit based on the two-port network principle.
A two-port network (two-port network) has only two external ports, which is also called a dual-port network. Two-port networks are often connected to each other in electronic circuits, and the connections between them are in 5 modes, i.e., series, parallel, series-parallel, parallel-series, and cascade, and the networks thus connected are still two-port networks. In the embodiment of the application, the equivalent circuit of the reactor can be in a parallel connection mode, and different connection modes can be selected according to actual requirements.
Based on the two-port network principle, a plurality of capacitors and a plurality of inductors in the reactor distribution parameter equivalent circuit of fig. 6 are equivalent to a reactor equivalent circuit with a capacitor and an inductor connected in parallel, as shown in fig. 7, the reactor equivalent circuit is formed by connecting a capacitor C and an inductor L in parallel.
In S103, a high-impedance transformer wave process simulation model is constructed based on the transformer distribution parameter equivalent circuit and the reactor equivalent circuit, and a voltage distribution parameter of the transformer is calculated based on the high-impedance transformer wave process simulation model, where the voltage distribution parameter of the transformer includes a transmission overvoltage at a low-voltage terminal of the transformer.
The transmission of the overvoltage refers to that when an asymmetric ground fault occurs in a system or a circuit breaker does not operate simultaneously, a power frequency voltage transmission phenomenon can be generated between adjacent transmission lines or between transformer windings through electrostatic and electromagnetic coupling of a zero-sequence power frequency voltage component which possibly occurs, so that the insulation safety of low-voltage side electrical equipment is endangered. If a resonant circuit is formed with a ferromagnetic element such as an arc suppression coil or a voltage transformer connected to a neutral point of a power supply, linear resonance or ferromagnetic resonance may occur to transmit an overvoltage.
In a possible implementation manner, constructing the high impedance transformer wave process simulation model based on the transformer distribution parameter equivalent circuit and the reactor equivalent circuit may include:
and connecting the equivalent circuit of the reactor in series at the tail end of the low-voltage coil of the equivalent circuit of the distribution parameters of the transformer to construct a simulation model of the wave process of the high-impedance transformer.
Referring to fig. 8, the reactor equivalent circuit in S102 is connected in series to the tail end of the low-voltage coil of the transformer distributed parameter equivalent circuit in S101, so as to construct a high-impedance transformer wave process simulation model.
In a possible implementation, the voltage distribution parameters of the transformer may further include a voltage to ground of each cell of the transformer and a voltage between cells in case of lightning surge overvoltage.
Here, a voltage to earth (voltage to earth), which is a potential difference between a zero potential point and a case, a ground line, a ground body, and the like of the ground device when the ground fault occurs in the electrical device, is referred to as a voltage to earth when the electrical device is grounded. In an electric power system, a ground voltage refers to a potential difference between a housing, a ground line, a ground body, and the like of a ground device and a zero potential point when an electrical device has a ground fault. The ground is usually set to a zero potential point.
In the embodiment of the application, on the basis of a simulation model of a high-impedance transformer wave process, a lightning surge overvoltage U is applied to a high-voltage head end A of a transformer, and the voltages to earth, among units and the transmission overvoltage U of a low-voltage end of each unit of the transformer are calculated x1 According to the earth voltage of each unit of the transformer, the voltage between the units and the transfer overvoltage U at the low-voltage terminal x1 The reliability of the insulation structure of the transformer was evaluated.
In one possible implementation, after the voltage distribution parameter of the transformer is calculated based on the high impedance transformer wave process simulation model, the method may further include:
calculating the electric field distribution from the low-voltage wire end of the transformer to the iron core according to the transmission overvoltage of the low-voltage wire end of the transformer, and using the electric field distribution as first electric field distribution;
and evaluating the reliability of the insulation structure from the low-voltage wire end of the transformer to the iron core according to the first electric field distribution.
Wherein, insulation system refers to a combination of one or several insulation materials. The electrical equipment is designed to be integrated with the conductor member according to the characteristics and size requirements of the electrical equipment, so as to isolate the conductive part with potential difference. It should be noted that several different insulation configurations are allowed in an electrical apparatus.
In the embodiment of the application, the overvoltage U is transmitted according to the low-voltage end terminal of the transformer x1 And calculating the electric field distribution from the low-voltage coil of the transformer to the iron core to obtain the electric field distribution from the low-voltage line end of the transformer to the iron core, and evaluating the reliability of the insulation structure from the low-voltage line end of the transformer to the iron core according to the electric field distribution from the low-voltage line end of the transformer to the iron core.
In S104, a voltage distribution parameter of the reactor is calculated based on the reactor distribution parameter equivalent circuit.
In one possible implementation, S104 may include:
and calculating the voltage distribution parameters of the reactor according to the reactor distribution parameter equivalent circuit and by taking the transmission overvoltage of the low-voltage line end of the transformer as excitation.
Referring to fig. 6, the overvoltage U is transmitted at the low voltage terminal of the transformer x1 With particular reference to fig. 9, fig. 9 shows the passing of an overvoltage U as excitation, i.e. as the line-end voltage of a distributed-parameter equivalent circuit of a reactor x1 And calculating the voltage distribution parameters of the reactor according to the reactor wave process simulation model as a reactor wave process simulation model for exciting the equivalent circuit based on the reactor distribution parameters.
In one possible implementation, the voltage distribution parameter of the reactor may include a voltage to ground of each cell of the reactor and a voltage between the cells.
According to the reactor wave process simulation model, the overvoltage U is transmitted by the low-voltage end of the transformer x1 As excitation, the voltage to ground and the voltage between cells of the reactor are calculated.
In one possible implementation manner, after S104, the method may further include:
calculating the electric field distribution from the coil of the reactor to the iron core and the oil tank according to the transmission overvoltage of the low-voltage terminal of the transformer, and taking the electric field distribution as second electric field distribution;
and evaluating the reliability of the insulation structure from the coil of the reactor to the iron core and the oil tank according to the second electric field distribution.
In the embodiment of the application, the overvoltage U is transmitted according to the low-voltage end terminal of the transformer x1 And calculating the electric field distribution from the coil of the reactor to the iron core and the oil tank, and evaluating the reliability of the insulation structure from the coil of the reactor to the iron core and the oil tank according to the electric field distribution from the coil of the reactor to the iron core and the oil tank.
In the embodiment of the application, the reliability of the insulation structure of the reactor is jointly evaluated according to the voltage to ground of each unit of the reactor, the voltage between the units and the electric field distribution of the coil to the iron core and the oil tank.
For example, for a high impedance transformer to be put into use:
firstly, according to the wave process wiring schematic diagram of the high-impedance transformer with series impedance and the operation mode of the high-impedance transformer, the high-impedance transformer is wired according to the wave process wiring schematic diagram of the high-impedance transformer with series impedance, referring to fig. 4, the high-voltage head end a of the transformer is connected with an overvoltage inlet, and the high-voltage tail end X and the low-voltage head end a of the transformer and the X end of the reactor are grounded.
Secondly, according to the winding structures of the transformer and the reactor, the windings of the transformer and the reactor in the high-impedance transformer are divided into a plurality of units, the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the windings of the transformer are calculated, the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the windings of the reactor are calculated, a transformer distribution parameter equivalent circuit is constructed according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the windings of the transformer, and the transformer distribution parameter equivalent circuit refers to fig. 5; a reactor distribution parameter equivalent circuit is constructed from the series capacitance, the parallel capacitance, the self inductance, and the mutual inductance of each unit of the winding of the reactor, and is referred to fig. 6.
Thirdly, based on the two-port network principle, the equivalent circuit of the distributed parameters of the reactor is equivalent to an equivalent circuit of the reactor, the equivalent circuit of the reactor refers to fig. 7, and the equivalent circuit is formed by connecting a capacitor C and an inductor L in parallel.
Fourthly, serially connecting the equivalent circuit of the reactor at the tail end of the low-voltage coil of the equivalent circuit of the distribution parameters of the transformer to construct a high-impedance transformer wave process simulation model, and calculating the voltage to earth of each unit of the transformer, the voltage among the units and the transmission overvoltage U at the low-voltage end of the transformer under the lightning surge overvoltage U according to the high-impedance transformer wave process simulation model x1 Wherein the overvoltage U is transmitted according to the voltage to ground of each unit of the transformer under the lightning surge overvoltage U, the voltage between the units and the low voltage terminal of the transformer x1 Evaluating the reliability of the insulation structure of the transformer; according to the transmission overvoltage U of the low-voltage terminal of the transformer x1 Calculating the electric field distribution from the low-voltage line end of the transformer to the iron core, and calculating the electric field distribution from the low-voltage line end of the transformer to the iron core according to the electric field distributionThe electric field distribution of the core evaluates the reliability of the insulation structure from the low-voltage wire end of the transformer to the iron core.
Fifthly, the overvoltage U is transmitted by the low-voltage end of the transformer x1 As excitation, the voltage to ground and the voltage between the units of the reactor are calculated according to the equivalent circuit of the reactor distribution parameter, and the transmission overvoltage U is transmitted based on the low-voltage end of the transformer x1 Calculating the electric field distribution from the coil of the reactor to the iron core and the oil tank, wherein the reliability of the insulation structure of the reactor is evaluated according to the voltage to earth of each unit of the reactor, the voltage between the units and the electric field distribution from the coil of the reactor to the iron core and the oil tank; and evaluating the reliability of the insulation structure from the coil of the reactor to the iron core and the oil tank according to the electric field distribution from the coil of the reactor to the iron core and the oil tank.
The method comprises the steps of respectively building a transformer distribution parameter equivalent circuit and a reactor distribution parameter equivalent circuit according to a wave process wiring schematic diagram of a high-impedance transformer with series impedance and winding structures of the transformer and a reactor; based on a two-port network principle, the equivalent circuit of the reactor distribution parameter is equivalent to an equivalent circuit of the reactor; constructing a high-impedance transformer wave process simulation model based on a transformer distribution parameter equivalent circuit and a reactor equivalent circuit, calculating to obtain a voltage distribution parameter of the transformer based on the high-impedance transformer wave process simulation model, and evaluating the reliability of the insulation structure of the transformer according to the voltage distribution parameter; the method and the device have the advantages that the voltage distribution parameters of the reactor are obtained through calculation based on the reactor distribution parameter equivalent circuit, the reliability of the insulation structure of the reactor can be evaluated according to the voltage distribution parameters, the single equipment wave process distribution under the condition of series connection of multiple equipment can be accurately calculated according to the winding structure of the high-impedance transformer with the series impedance, and the insulation reliability of the high-impedance transformer with the series impedance is guaranteed based on the reactor distribution parameter equivalent circuit.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
The above-mentioned embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the embodiments of the present application, and they should be construed as being included in the present application.
Claims (10)
1. A transformer wave process equivalent calculation method is characterized by comprising the following steps:
respectively building a transformer distribution parameter equivalent circuit and a reactor distribution parameter equivalent circuit according to a wave process wiring schematic diagram of a high-impedance transformer with a series impedance and winding structures of the transformer and the reactor;
based on a two-port network principle, the reactor distribution parameter equivalent circuit is equivalent to a reactor equivalent circuit;
constructing a high-impedance transformer wave process simulation model based on the transformer distribution parameter equivalent circuit and the reactor equivalent circuit, and calculating to obtain voltage distribution parameters of the transformer based on the high-impedance transformer wave process simulation model, wherein the voltage distribution parameters of the transformer comprise transmission overvoltage of a low-voltage line end of the transformer;
and calculating the voltage distribution parameters of the reactor based on the equivalent circuit of the distribution parameters of the reactor.
2. The transformer wave process equivalent calculation method according to claim 1, wherein the step of respectively building a transformer distribution parameter equivalent circuit and a reactor distribution parameter equivalent circuit according to the wave process wiring schematic diagram of the high-impedance transformer with the series impedance and the winding structures of the transformer and the reactor comprises the following steps of:
establishing a wave process wiring schematic diagram of the high-impedance transformer with the series impedance according to the operation mode of the high-impedance transformer;
calculating the series capacitance, the parallel capacitance, the self inductance and the mutual inductance of the transformer according to the wave process wiring schematic diagram of the high-impedance transformer with the series impedance and the winding structure of the transformer, and constructing a transformer distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self inductance and the mutual inductance of the transformer;
calculating the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the reactor according to the wave process wiring schematic diagram of the high-impedance transformer with the series impedance and the winding structure of the reactor, and constructing a distributed parameter equivalent circuit of the reactor according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the reactor.
3. The transformer wave process equivalence calculation method according to claim 1, wherein the constructing a high-impedance transformer wave process simulation model based on the transformer distribution parameter equivalent circuit and the reactor equivalent circuit comprises:
and connecting the equivalent circuit of the reactor in series at the tail end of the low-voltage coil of the equivalent circuit of the distribution parameters of the transformer to construct a simulation model of the wave process of the high-impedance transformer.
4. The transformer wave process equivalence calculation method according to claim 2, wherein the calculating of the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the transformer according to the wave process wiring schematic diagram of the series impedance high-impedance transformer and the winding structure of the transformer, and the constructing of the transformer distributed parameter equivalence circuit according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the transformer comprise:
dividing the winding of the transformer into a plurality of units according to the wave process wiring schematic diagram of the high-impedance transformer with the series impedance and the winding structure of the transformer, calculating the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the transformer, and constructing a transformer distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the transformer.
5. The transformer wave process equivalence calculation method according to claim 4, wherein the voltage distribution parameters of the transformer further comprise voltages to ground and voltages between cells of the transformer under lightning surge overvoltage.
6. The transformer wave process equivalence calculation method according to claim 1, wherein after the calculating of the voltage distribution parameters of the transformer based on the high impedance transformer wave process simulation model, the method further comprises:
calculating the electric field distribution from the low-voltage wire end of the transformer to the iron core according to the transmission overvoltage of the low-voltage wire end of the transformer, and taking the electric field distribution as first electric field distribution;
and evaluating the reliability of the insulation structure from the low-voltage line end of the transformer to the iron core according to the first electric field distribution.
7. The transformer wave process equivalence calculation method according to claim 1, wherein the calculating of the voltage distribution parameters of the reactor based on the reactor distribution parameter equivalence circuit includes:
and calculating to obtain the voltage distribution parameters of the reactor according to the equivalent circuit of the distribution parameters of the reactor and by taking the transmission overvoltage of the low-voltage line end of the transformer as excitation.
8. The transformer wave process equivalence calculation method according to claim 2, wherein the calculating of the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the reactor according to the wave process wiring schematic diagram of the series impedance high-impedance transformer and the winding structure of the reactor, and the constructing of the reactor distribution parameter equivalence circuit according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of the reactor comprise:
dividing the winding of the reactor into a plurality of units according to the wave process wiring schematic diagram of the high-impedance transformer with the series impedance and the winding structure of the reactor, calculating the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the reactor, and constructing a reactor distribution parameter equivalent circuit according to the series capacitance, the parallel capacitance, the self-inductance and the mutual inductance of each unit of the winding of the reactor.
9. The transformer wave process equivalence calculation method according to claim 8, wherein the voltage distribution parameters of the reactor include a voltage to ground of each cell of the reactor and a voltage between cells.
10. The transformer wave process equivalence calculation method according to claim 1, wherein after the calculating of the voltage distribution parameter of the reactor based on the reactor distribution parameter equivalence circuit, the method further comprises:
calculating the electric field distribution from the coil of the reactor to the iron core and the oil tank according to the transmission overvoltage of the low-voltage terminal of the transformer, and taking the electric field distribution as second electric field distribution;
and evaluating the reliability of the insulation structure from the coil of the reactor to the iron core and the oil tank according to the second electric field distribution.
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