CN110632394A - Circuit impedance characteristic simulation system - Google Patents
Circuit impedance characteristic simulation system Download PDFInfo
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- CN110632394A CN110632394A CN201911016835.5A CN201911016835A CN110632394A CN 110632394 A CN110632394 A CN 110632394A CN 201911016835 A CN201911016835 A CN 201911016835A CN 110632394 A CN110632394 A CN 110632394A
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- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/08—Measuring resistance by measuring both voltage and current
Abstract
The invention discloses a circuit impedance characteristic simulation system, which comprises: the system comprises a simulation traction network power supply, a relay protection device, a voltage regulator, a line impedance characteristic simulator, a load, a harmonic generator, a controller and a voltage and current acquisition device; the harmonic generator sends a harmonic voltage component corresponding to the harmonic instruction through carrier phase shift modulation according to the harmonic instruction sent by the controller, and the harmonic voltage component is converted into a harmonic current component through the line impedance characteristic simulator and the voltage regulator in sequence and is injected into the simulation traction network; and then, the voltage and current acquisition device acquires the primary side voltage current and the secondary side voltage current of the voltage regulator and outputs the primary side voltage current and the secondary side voltage current to the controller, so that the controller obtains the traction network harmonic impedance under the harmonic frequency contained in the harmonic instruction according to the primary side voltage current and the secondary side voltage current. Therefore, the invention realizes the simulation of the harmonic impedance of the traction network and provides a basis for the research of the resonance characteristics of the circuit.
Description
Technical Field
The invention relates to the technical field of electricity, in particular to a circuit impedance characteristic simulation system.
Background
In recent years, high-speed electrified railways develop rapidly in China, and with the application of a large number of alternating current and direct current locomotives (motor train units) on the high-speed railways, the problem of matching relation between the alternating current and direct current locomotives and a traction network is increasingly prominent, and the problem is mainly expressed as the problem of higher harmonic resonance between the alternating current and direct current locomotives and the traction network.
The difference of the short circuit capacity of the external power supply of the traction power supply system is large, so that the difference of the system impedance equivalent to the inlet wire of the traction power supply system is large. In addition, the traction power supply system has the characteristics that the characteristic frequency of the traction power supply system has diversification due to the change of running modes such as cross-zone power supply and the like, which causes the change of equivalent parameters of the system. Meanwhile, the electric parameters of the direct power supply system and the AT power supply system adopted by the electric railway are different. Therefore, the harmonic frequency spectrum of the AC/DC locomotive and the characteristic frequency change of the traction power supply system cause higher harmonic amplification, and resonance has randomness.
In summary, how to provide a circuit impedance characteristic simulation system to realize simulation of the harmonic impedance of the traction network, so as to provide a basis for the research of the resonance characteristic of the circuit, which is a technical problem that those skilled in the art need to solve urgently.
Disclosure of Invention
In view of this, the invention discloses a line impedance characteristic simulation system to realize simulation of harmonic impedance of a traction network, thereby providing a basis for research of line resonance characteristics.
A line impedance characteristic simulation system, comprising: the system comprises a simulation traction network power supply, a relay protection device, a voltage regulator, a line impedance characteristic simulator, a load, a harmonic generator, a controller and a voltage and current acquisition device;
the simulation traction network power supply is connected with the input end of the line impedance characteristic simulator sequentially through the relay protection device and the voltage regulator, and the output end of the line impedance characteristic simulator is connected with the load;
the line impedance characteristic simulator is used for simulating line impedance characteristics;
the relay protection device is used for performing overvoltage protection on the simulation traction network power supply;
a signal control port of the controller is respectively connected with a control end of the line impedance characteristic simulator and an input end of the harmonic generator, and an output end of the harmonic generator is connected with a common end of the line impedance characteristic simulator and the load;
the harmonic generator is used for sending a harmonic voltage component corresponding to a harmonic instruction through carrier phase shift modulation according to the harmonic instruction which is sent by the controller and contains harmonic frequency and harmonic amplitude, and the harmonic voltage component is converted into a harmonic current component through the line impedance characteristic simulator and the voltage regulator in sequence and is injected into the simulation traction network;
the input end of the voltage and current acquisition device is respectively connected with the input end of the voltage regulator and the output end of the voltage regulator, the output end of the voltage and current acquisition device is connected with the signal acquisition end of the controller, and the voltage and current acquisition device is used for acquiring primary side voltage current and secondary side voltage current of the voltage regulator and outputting the primary side voltage current and the secondary side voltage current to the controller, so that the controller can obtain traction network harmonic impedance under harmonic frequency contained by the harmonic instruction according to the primary side voltage current and the secondary side voltage current.
Optionally, the voltage regulator is a step-down transformer.
Optionally, a digital signal processor is used as a controller in the harmonic generator, an IGBT is used as a switching device, and a three-level topology is adopted.
Optionally, the line impedance characteristic simulator includes: the circuit impedance characteristic simulator comprises an adjustable resistor, an adjustable capacitor and an adjustable reactor, wherein one end of the adjustable resistor is used as an input end of the circuit impedance characteristic simulator, the other end of the adjustable resistor is connected with one end of the adjustable reactor, the other end of the adjustable reactor is used as an output end of the circuit impedance characteristic simulator, one end of the adjustable capacitor is connected with a common end of the adjustable resistor and the adjustable reactor, and the other end of the adjustable capacitor is grounded.
Optionally, the voltage and current collecting device includes: the transformer comprises a first current transformer, a second current transformer, a first voltage transformer and a second voltage transformer;
the first current transformer is arranged at the input end of the voltage regulator and used for collecting primary side current;
the second current transformer is arranged at the output end of the voltage regulator and used for collecting secondary side current;
the first voltage transformer is arranged at the input end of the voltage regulator and used for collecting primary side voltage;
and the second voltage transformer is used for being arranged at the output end of the voltage regulator and collecting the secondary side voltage.
Optionally, the method further includes: the device comprises a power quality optimizing device and a circuit breaker;
one end of the electric energy quality optimization device is connected with the controller and the voltage and current acquisition device respectively, the other end of the electric energy quality optimization device is connected between the voltage regulator and the load through the circuit breaker, and the electric energy quality optimization device is used for filtering the primary side voltage current and the secondary side voltage current output by the voltage and current acquisition device and outputting the filtered primary side voltage current and the filtered secondary side voltage current to the controller.
Optionally, the power quality optimizing device is a filter.
Optionally, the controller is further configured to obtain a harmonic current in the traction network simulated by the power quality optimization device at different access positions between the voltage regulator and the load, analyze a filtering effect of the power quality optimization device at different access points according to a harmonic component included in the harmonic current, and determine an optimal access scheme of the power quality optimization device according to the filtering effect.
Optionally, the controller is further configured to repeatedly send a harmonic instruction including different test harmonic frequencies to the harmonic generator for multiple times, calculate to obtain corresponding traction network harmonic impedance until the test harmonic frequency range includes a preset frequency range, and draw a line impedance frequency characteristic curve according to a correspondence between the different test harmonic frequencies and the traction network harmonic impedance.
Optionally, when the impedance characteristic of the line is unknown, the harmonic spectrum of the line is equivalent to a T-shaped structure by using the karson theory, the T-shaped structure is determined as the theoretical impedance characteristic of the line, and the parameter configuration of the line impedance characteristic simulator is performed according to the theoretical impedance characteristic of the line, so as to obtain the line impedance characteristic simulator.
Optionally, when the line impedance characteristic is known, the line impedance characteristic simulator is obtained by configuring parameters of the line impedance characteristic simulator according to the known line impedance characteristic.
From the above technical solution, the present invention discloses a line impedance characteristic simulation system, including: the system comprises a simulation traction network power supply, a relay protection device, a voltage regulator, a line impedance characteristic simulator, a load, a harmonic generator, a controller and a voltage and current acquisition device; the harmonic generator sends a harmonic voltage component corresponding to the harmonic instruction through carrier phase shift modulation according to the harmonic instruction which is sent by the controller and contains harmonic frequency and harmonic amplitude, and the harmonic voltage component is converted into a harmonic current component through the line impedance characteristic simulator and the voltage regulator in sequence and is injected into the simulation traction network; and then, the voltage and current acquisition device acquires the primary side voltage current and the secondary side voltage current of the voltage regulator and outputs the primary side voltage current and the secondary side voltage current to the controller, so that the controller obtains the traction network harmonic impedance under the harmonic frequency contained in the harmonic instruction according to the primary side voltage current and the secondary side voltage current. Therefore, the invention realizes the simulation of the harmonic impedance of the traction network, thereby providing a basis for the research of the resonance characteristic of the circuit.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the disclosed drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a circuit impedance characteristic simulation system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a circuit impedance characteristic simulator according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of another line impedance characteristic simulation system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
After research, the inventor of the invention finds that the resonance of the traction power supply system can be approximately regarded as the parallel resonance of the distributed capacitance of the traction network and the equivalent inductance (including the leakage inductance of the transformer and the system inductance) of the power supply. The resonance frequency of the traction network is determined by the electrical parameters of the traction network and the frequency characteristics of the transformer and the impedance of the system, and is independent of the load position. The longer the supply arm, the greater the total distributed capacitance, and the lower the traction network resonant frequency, which is approximately inversely proportional to the square root of the supply arm length.
Based on this, the embodiment of the invention discloses a line impedance characteristic simulation system, which comprises: the system comprises a simulation traction network power supply, a relay protection device, a voltage regulator, a line impedance characteristic simulator, a load, a harmonic generator, a controller and a voltage and current acquisition device; the harmonic generator sends a harmonic voltage component corresponding to the harmonic instruction through carrier phase shift modulation according to the harmonic instruction which is sent by the controller and contains harmonic frequency and harmonic amplitude, and the harmonic voltage component is converted into a harmonic current component through the line impedance characteristic simulator and the voltage regulator in sequence and is injected into the simulation traction network; and then, the voltage and current acquisition device acquires the primary side voltage current and the secondary side voltage current of the voltage regulator and outputs the primary side voltage current and the secondary side voltage current to the controller, so that the controller obtains the traction network harmonic impedance under the harmonic frequency contained in the harmonic instruction according to the primary side voltage current and the secondary side voltage current. Therefore, the invention realizes the simulation of the harmonic impedance of the traction network, thereby providing a basis for the research of the resonance characteristic of the circuit.
Referring to fig. 1, a schematic structural diagram of a circuit impedance characteristic simulation system according to an embodiment of the present invention includes: the system comprises a simulated traction network power supply 11, a relay protection device 12, a voltage regulator 13, a line impedance characteristic simulator 14, a load 15, a harmonic generator 16, a controller 17 and a voltage and current acquisition device 18.
Wherein:
the analog traction network power supply 11 can adopt a single-phase power supply, the voltage of the single-phase power supply is 380V, and the frequency is 50HZ。
The simulated traction network power supply 11 is connected with the input end of a line impedance characteristic simulator 14 sequentially through a relay protection device 12 and a voltage regulator 13, the output end of the line impedance characteristic simulator 14 is connected with a load 15, and the line impedance characteristic simulator 14 is used for simulating line impedance characteristics.
Preferably, the voltage regulator 13 is a step-down transformer for stepping down 380V to 220V.
Due to the complexity of equivalent calculation of the traction network, the line impedance characteristic simulator 14 generally considers that harmful parallel resonance occurs only when some frequencies of traction harmonics of a locomotive coincide with characteristic frequency points of line impedance frequency characteristics and the amplitude exceeds a preset value, for convenience of analysis, the line impedance characteristic simulator is constructed by considering only the characteristic frequency points and re-fitting a line impedance characteristic curve according to the characteristic frequency points, and the structure of the line impedance characteristic simulator 14 can be a T-shaped structure or a pi-shaped structure or other two-port model structures.
In this embodiment, the relay protection device 12 is used to perform overvoltage protection on the analog traction network power supply 11.
The relay protection is an important measure for detecting faults or abnormal conditions occurring in the power system so as to send out alarm signals or directly isolate and remove fault parts.
A signal control port of the controller 17 is connected with a control end of the line impedance characteristic simulator 14 and an input end of the harmonic generator 16 respectively, an output end of the harmonic generator 16 is connected with a common end of the line impedance characteristic simulator 14 and the load 15, the harmonic generator 16 is used for sending a harmonic voltage component corresponding to a harmonic instruction through carrier phase shift modulation according to the harmonic instruction which is sent by the controller 17 and contains harmonic frequency and harmonic amplitude, and the harmonic voltage component is converted into a harmonic current component through the line impedance characteristic simulator 14 and the voltage regulator 13 in sequence and is injected into a simulation traction network.
It should be noted that, in practical applications, the upper computer 10 connected to the controller 17 may be operated to set harmonic commands including harmonic frequencies and harmonic amplitudes.
The input end of the voltage and current acquisition device 18 is connected with the input end of the voltage regulator 13 and the output end of the voltage regulator 13 respectively, the output end of the voltage and current acquisition device 18 is connected with the signal acquisition end of the controller 17, the voltage and current acquisition device 18 is used for acquiring the primary side voltage current and the secondary side voltage current of the voltage regulator 13 and outputting the primary side voltage current and the secondary side voltage current to the controller 17, so that the controller 17 can obtain the traction network harmonic impedance under the harmonic frequency contained in the harmonic instruction according to the primary side voltage current and the secondary side voltage current.
In summary, the present invention discloses a system for simulating line impedance characteristics, comprising: the system comprises a simulation traction network power supply, a relay protection device, a voltage regulator, a line impedance characteristic simulator, a load, a harmonic generator, a controller and a voltage and current acquisition device; the harmonic generator sends a harmonic voltage component corresponding to the harmonic instruction through carrier phase shift modulation according to the harmonic instruction which is sent by the controller and contains harmonic frequency and harmonic amplitude, and the harmonic voltage component is converted into a harmonic current component through the line impedance characteristic simulator and the voltage regulator in sequence and is injected into the simulation traction network; and then, the voltage and current acquisition device acquires the primary side voltage current and the secondary side voltage current of the voltage regulator and outputs the primary side voltage current and the secondary side voltage current to the controller, so that the controller obtains the traction network harmonic impedance under the harmonic frequency contained in the harmonic instruction according to the primary side voltage current and the secondary side voltage current. Therefore, the invention realizes the simulation of the harmonic impedance of the traction network, thereby providing a basis for the research of the resonance characteristic of the circuit.
Preferably, the harmonic generator 16 uses a digital signal processor as a controller, an IGBT (Insulated Gate Bipolar Transistor) as a switching device, and a three-level topology, and outputs a current of 0 to 20A and a harmonic order of 2 to 53 (which may be stacked).
The harmonic generator 16 is composed of a single-phase neutral point clamped three-level back-to-back converter, and the power device is an IGBT.
Referring to fig. 2, a schematic structural diagram of a line impedance characteristic simulator according to an embodiment of the present invention is disclosed, in which the line impedance characteristic simulator 14 includes: the circuit impedance characteristic simulator comprises an adjustable resistor R, an adjustable capacitor C and an adjustable reactor L, wherein one end of the adjustable resistor R is used as the input end of the circuit impedance characteristic simulator 14, the other end of the adjustable resistor R is connected with one end of the adjustable reactor L, the other end of the adjustable reactor L is used as the output end of the circuit impedance characteristic simulator 14, one end of the adjustable capacitor C is connected with the common end of the adjustable resistor R and the adjustable reactor L, and the other end of the adjustable capacitor C is grounded.
In this embodiment, the voltage and current collecting device 18 includes: the transformer comprises a first current transformer, a second current transformer, a first voltage transformer and a second voltage transformer.
The first current transformer is used for being arranged at the input end of the voltage regulator 13 and collecting primary side current, and the second current transformer is used for being arranged at the output end of the voltage regulator 13 and collecting secondary side current.
The first voltage transformer is used for being arranged at the input end of the voltage regulator 13 and collecting primary side voltage, and the second voltage transformer is used for being arranged at the output end of the voltage regulator 13 and collecting secondary side voltage.
To further optimize the above embodiment, the controller 17 may be further configured to: and repeatedly sending harmonic instructions containing different test harmonic frequencies to the harmonic generator 16 for many times, calculating to obtain corresponding traction network harmonic impedance until the range of the test harmonic frequencies contains a preset frequency range, and drawing a line impedance frequency characteristic curve according to the corresponding relation between the different test harmonic frequencies and the traction network harmonic impedance.
The preset frequency range may be: 100Hz-2650 Hz.
It should be noted that, after the line impedance frequency characteristic curve is obtained by drawing, the access position of the power quality optimization device 19 in the line can be determined according to the line impedance frequency characteristic curve, and the performance of the power quality optimization device 19 can be analyzed.
Therefore, referring to fig. 3, a schematic structural diagram of a circuit impedance characteristic simulation system according to an embodiment of the present invention may further include, on the basis of the embodiment shown in fig. 1: a power quality optimizing device 19 and a circuit breaker 20;
one end of the power quality optimizing device 19 is connected with the controller 17 and the voltage and current collecting device 18, the other end of the power quality optimizing device 19 is connected between the voltage regulator 13 and the load 15 through the breaker 20, and the power quality optimizing device 19 is used for filtering the primary side voltage current and the secondary side voltage current output by the voltage and current collecting device 18 and outputting the filtered primary side voltage current and the filtered secondary side voltage current to the controller 17.
Optionally, the power quality optimizing device 19 is a filter.
It should be noted that, in practical applications, the other end of the power quality optimization device 19 may be connected to any position between the voltage regulator 13 and the load 15 through the circuit breaker 20, and therefore, the controller 17 may determine the optimal connection scheme of the power quality optimization device 19 by analyzing the filtering effects of the power quality optimization device 19 at different access points.
Specifically, the controller 17 sends harmonic instructions containing different frequencies and amplitudes to the harmonic generator 16, the harmonic generator 16 sends harmonic voltage components corresponding to the harmonic instructions through carrier phase shift modulation according to the harmonic instructions containing harmonic frequencies and harmonic amplitudes sent by the controller 17, the harmonic voltage components are converted into harmonic current components through the line impedance characteristic simulator 14 and the voltage regulator 13 in sequence and are injected into the simulated traction network, and the controller 17 obtains components of harmonic currents in the simulated traction network.
And changing the access position of the electric energy quality optimizing device 19, repeating the steps, analyzing the filtering effects of the electric energy quality optimizing device 19 at different access points, and determining the optimal access scheme of the electric energy quality optimizing device 19.
Therefore, the controller 17 is further configured to obtain a harmonic current in the traction network simulated by the power quality optimization device 19 at different access positions between the voltage regulator 13 and the load 15, analyze the filtering effects of the power quality optimization device 19 at different access points according to the harmonic component included in the harmonic current, and determine the optimal access scheme of the power quality optimization device 19 according to the filtering effects.
It should be noted that, the line impedance characteristic simulation system disclosed in the present invention may include two operation modes, the first mode is known line impedance characteristic, in this case, the line impedance characteristic simulator may be configured according to the characteristic frequency point; the second method is unknown line impedance characteristics, in this case, an input file (containing harmonic frequency spectrum) is designed for a known traction power supply system, a theoretical line impedance characteristic is obtained by adopting the Karson theory, and then a line impedance characteristic simulator is configured according to the calculated theoretical line impedance characteristic.
The specific process is as follows:
(1) known line impedance characteristics
The line impedance characteristic simulator 14 is obtained by configuring the parameters of the line impedance characteristic simulator according to the line impedance characteristics.
The line impedance characteristic simulator 14 is connected with the simulated traction network power supply 11 through the voltage regulator 13, the load 15 selects a pure resistive load, the harmonic generator 16 is merged into the front end of the load, the electric energy quality optimization device 19 can be merged into any position between the voltage regulator 13 and the load 15, the voltage and current acquisition device 18 acquires primary side voltage current and secondary side voltage current of the voltage regulator 13 and outputs the primary side voltage current and the secondary side voltage current to the controller 17 and the electric energy quality optimization device 19, and the controller 17 injects each subharmonic into the system through the harmonic generator 16 in sequence to obtain a line impedance frequency characteristic curve of the line impedance characteristic simulator 14.
It should be noted that the power quality optimizing device 19 may be an active filter or a passive filter, and when the power quality optimizing device 19 is the passive filter, the primary side voltage current and the secondary side voltage current of the voltage regulator 13 collected by the voltage current collecting device 18 do not need to be input to the power quality optimizing device 19.
The controller 17 injects each harmonic into the system in sequence through the harmonic generator 16 to obtain a line impedance frequency characteristic curve of the line impedance characteristic simulator 14, and the method specifically includes:
the controller 17 sends harmonic instructions containing different frequencies and amplitudes to the harmonic generator 16, the harmonic generator 16 is used for sending harmonic voltage components corresponding to the harmonic instructions through carrier phase shift modulation according to the harmonic instructions containing harmonic frequencies and harmonic amplitudes sent by the controller 17, the harmonic voltage components are converted into harmonic current components through the line impedance characteristic simulator 14 and the voltage regulator 13 in sequence and are injected into the analog traction network, the voltage and current acquisition device 18 acquires primary side voltage current and secondary side voltage current of the voltage regulator 13 and outputs the primary side voltage current and the secondary side voltage current to the controller 17, so that the controller 17 obtains the traction network harmonic impedance under the harmonic frequencies according to the primary side voltage current and the secondary side voltage current.
If there is a new characteristic frequency point within a preset number, for example, 50, then injection of harmonics of that frequency is avoided on subsequent trials.
In particular, when a voltage of the analog traction network power supply 11 rises due to parallel resonance when harmonics are injected into the system, the analog traction network power supply 11 is subjected to overvoltage protection by the relay protection device 12.
(2) Unknown line impedance characteristics
Knowing the harmonic spectrum of the line, adopting the Karson theory to be equivalent to a T-shaped structure to the harmonic spectrum, determining the T-shaped structure as the theoretical line impedance characteristic, and performing parameter configuration of the line impedance characteristic simulator according to the theoretical line impedance characteristic to obtain the line impedance characteristic simulator 14.
The line impedance characteristic simulator 14 is connected with the simulated traction network power supply 11 through the voltage regulator 13, the load 15 selects a pure resistive load, the harmonic generator 16 is merged into the front end of the load, the electric energy quality optimization device 19 can be merged into any position between the voltage regulator 13 and the load 15, the voltage and current acquisition device 18 acquires primary side voltage current and secondary side voltage current of the voltage regulator 13 and outputs the primary side voltage current and the secondary side voltage current to the controller 17 and the electric energy quality optimization device 19, and the controller 17 injects each subharmonic into the system through the harmonic generator 16 in sequence to obtain a measured line impedance frequency characteristic curve of the line impedance characteristic simulator 14.
Comparing the obtained measured line impedance frequency characteristic curve with the actually measured actual line impedance frequency characteristic curve to determine whether the two curves are consistent, and if so, determining that the line impedance characteristic simulator 14 obtained according to the theoretical line impedance characteristic is correct; if the two are not consistent, the parameters in the line impedance characteristic simulator 14 are adjusted according to the actual line impedance frequency characteristic curve, so that the actual line impedance frequency characteristic curve and the measured line impedance frequency characteristic curve tend to be consistent.
In the above embodiment, the method for analyzing the harmonic and line impedance frequency characteristics includes:
for a single phase circuit, a virtual α - β coordinate system can be constructed. Us being the supply voltage of the analogue traction network, iSIs the supply current iLIs the load current iFA current is injected for the harmonics generator. The expression for the load current is:
iL＝ip+iq+ih (1)；
in the formula ipAs the fundamental active current, iqIs a fundamental reactive current, ihIs the load harmonic current.
In the formula, E is the effective value of the power supply voltage of the analog traction network, omega is the fundamental wave angular frequency, t is the sampling time,
is the initial phase.
Since the active current is equal to the total current multiplied by the power factor
Reactive current equal to total current multiplied byThus, the following formula is obtained:
in the formula ispIs the active current (s ∈ N), isqIs the reactive current (s e N),
the phase angle of the current hysteresis voltage.
By coordinate transformation, the variable active current i in the static coordinate systemspAnd a reactive current isqTo convertFor rotating the vector, the active current i in the rotating coordinate system can be obtainedpAnd a reactive current iq. See equation (4):
when n is 1, entering formula (2), calculating to obtain fundamental wave active current i1pAnd fundamental reactive current i1qThe formula is as follows:
the fundamental wave active current is subtracted from the power supply current to obtain harmonic waves and reactive current, so that the electric quantity content of each harmonic wave can be known, and the harmonic wave content corresponding to the characteristic frequency point can be analyzed.
In summary, the present invention discloses a system for simulating line impedance characteristics, comprising: the system comprises a simulation traction network power supply, a relay protection device, a voltage regulator, a line impedance characteristic simulator, a load, a harmonic generator, a controller and a voltage and current acquisition device; the harmonic generator sends a harmonic voltage component corresponding to the harmonic instruction through carrier phase shift modulation according to the harmonic instruction which is sent by the controller and contains harmonic frequency and harmonic amplitude, and the harmonic voltage component is converted into a harmonic current component through the line impedance characteristic simulator and the voltage regulator in sequence and is injected into the simulation traction network; and then, the voltage and current acquisition device acquires the primary side voltage current and the secondary side voltage current of the voltage regulator and outputs the primary side voltage current and the secondary side voltage current to the controller, so that the controller obtains the traction network harmonic impedance under the harmonic frequency contained in the harmonic instruction according to the primary side voltage current and the secondary side voltage current. Therefore, the invention realizes the simulation of the harmonic impedance of the traction network, thereby providing a basis for the research of the resonance characteristic of the circuit.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (11)
1. A system for simulating impedance characteristics of a line, comprising: the system comprises a simulation traction network power supply, a relay protection device, a voltage regulator, a line impedance characteristic simulator, a load, a harmonic generator, a controller and a voltage and current acquisition device;
the simulation traction network power supply is connected with the input end of the line impedance characteristic simulator sequentially through the relay protection device and the voltage regulator, and the output end of the line impedance characteristic simulator is connected with the load;
the line impedance characteristic simulator is used for simulating line impedance characteristics;
the relay protection device is used for performing overvoltage protection on the simulation traction network power supply;
a signal control port of the controller is respectively connected with a control end of the line impedance characteristic simulator and an input end of the harmonic generator, and an output end of the harmonic generator is connected with a common end of the line impedance characteristic simulator and the load;
the harmonic generator is used for sending a harmonic voltage component corresponding to a harmonic instruction through carrier phase shift modulation according to the harmonic instruction which is sent by the controller and contains harmonic frequency and harmonic amplitude, and the harmonic voltage component is converted into a harmonic current component through the line impedance characteristic simulator and the voltage regulator in sequence and is injected into the simulation traction network;
the input end of the voltage and current acquisition device is respectively connected with the input end of the voltage regulator and the output end of the voltage regulator, the output end of the voltage and current acquisition device is connected with the signal acquisition end of the controller, and the voltage and current acquisition device is used for acquiring primary side voltage current and secondary side voltage current of the voltage regulator and outputting the primary side voltage current and the secondary side voltage current to the controller, so that the controller can obtain traction network harmonic impedance under harmonic frequency contained by the harmonic instruction according to the primary side voltage current and the secondary side voltage current.
2. The line impedance characterization simulation system of claim 1, wherein the voltage regulator is a step-down transformer.
3. The line impedance characterization simulation system of claim 1 wherein the harmonics generator uses a digital signal processor as a controller, an IGBT as a switching device, and a three-level topology internally.
4. The line impedance characterization simulation system of claim 1, wherein the line impedance characterization simulator comprises: the circuit impedance characteristic simulator comprises an adjustable resistor, an adjustable capacitor and an adjustable reactor, wherein one end of the adjustable resistor is used as an input end of the circuit impedance characteristic simulator, the other end of the adjustable resistor is connected with one end of the adjustable reactor, the other end of the adjustable reactor is used as an output end of the circuit impedance characteristic simulator, one end of the adjustable capacitor is connected with a common end of the adjustable resistor and the adjustable reactor, and the other end of the adjustable capacitor is grounded.
5. The line impedance characteristic simulation system of claim 1, wherein the voltage current collection device comprises: the transformer comprises a first current transformer, a second current transformer, a first voltage transformer and a second voltage transformer;
the first current transformer is arranged at the input end of the voltage regulator and used for collecting primary side current;
the second current transformer is arranged at the output end of the voltage regulator and used for collecting secondary side current;
the first voltage transformer is arranged at the input end of the voltage regulator and used for collecting primary side voltage;
and the second voltage transformer is used for being arranged at the output end of the voltage regulator and collecting the secondary side voltage.
6. The line impedance characteristic simulation system of claim 1, further comprising: the device comprises a power quality optimizing device and a circuit breaker;
one end of the electric energy quality optimization device is connected with the controller and the voltage and current acquisition device respectively, the other end of the electric energy quality optimization device is connected between the voltage regulator and the load through the circuit breaker, and the electric energy quality optimization device is used for filtering the primary side voltage current and the secondary side voltage current output by the voltage and current acquisition device and outputting the filtered primary side voltage current and the filtered secondary side voltage current to the controller.
7. The line impedance characterization simulation system of claim 6, wherein the power quality optimization device is a filter.
8. The line impedance characteristic simulation system of claim 6, wherein the controller is further configured to obtain harmonic currents in the traction network simulated by the power quality optimization device at different access positions between the voltage regulator and the load, analyze filtering effects of the power quality optimization device at different access points according to harmonic components included in the harmonic currents, and determine an optimal access scheme of the power quality optimization device according to the filtering effects.
9. The line impedance characteristic simulation system of claim 1, wherein the controller is further configured to repeatedly send a harmonic instruction including different test harmonic frequencies to the harmonic generator for a plurality of times, calculate to obtain corresponding traction network harmonic impedances until the range of the test harmonic frequencies includes a preset frequency range, and draw a line impedance frequency characteristic curve according to a corresponding relationship between the different test harmonic frequencies and the traction network harmonic impedances.
10. The line impedance characteristic simulation system according to claim 1, wherein when the line impedance characteristic of the line is unknown, a harmonic spectrum of the line is equivalent to a T-shaped structure by using a karson theory, the T-shaped structure is determined as a theoretical line impedance characteristic, and the line impedance characteristic simulator is obtained by performing parameter configuration of the line impedance characteristic simulator according to the theoretical line impedance characteristic.
11. The line impedance characteristic simulation system of claim 1, wherein when the line impedance characteristic is known, the line impedance characteristic simulator is obtained by configuring parameters of the line impedance characteristic simulator according to the known line impedance characteristic.
Priority Applications (1)
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112054512A (en) * | 2020-08-20 | 2020-12-08 | 三峡大学 | FCS-MPC control-based high-permeability active power distribution network power quality management method |
| CN112698065A (en) * | 2020-12-04 | 2021-04-23 | 国网上海能源互联网研究院有限公司 | Circuit equipment for serially connecting AC/DC analog impedance |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112054512A (en) * | 2020-08-20 | 2020-12-08 | 三峡大学 | FCS-MPC control-based high-permeability active power distribution network power quality management method |
| CN112054512B (en) * | 2020-08-20 | 2022-04-08 | 三峡大学 | FCS-MPC control-based high-permeability active power distribution network power quality management method |
| CN112698065A (en) * | 2020-12-04 | 2021-04-23 | 国网上海能源互联网研究院有限公司 | Circuit equipment for serially connecting AC/DC analog impedance |
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