CN112260256A - Oscillation suppression method and system based on selective virtual harmonic resistance - Google Patents
Oscillation suppression method and system based on selective virtual harmonic resistance Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/05—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation specially adapted for damping motor oscillations, e.g. for reducing hunting
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
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Abstract
The invention discloses an oscillation suppression method and system based on selective virtual harmonic resistance, and the method comprises the following steps: constructing a instability suppression system based on the selective virtual harmonic resistance according to the selective virtual harmonic resistance suppression strategy and a direct-current side equivalent circuit of the subway traction transmission system; according to a constructed characteristic equation based on the selective virtual harmonic resistance instability suppression system and a system gradual stability criterion, calculating to obtain a voltage compensation parameter under a synchronous rotation coordinate system meeting the stability criterion condition; and inputting the calculated voltage compensation parameters under the synchronous rotation coordinate system into a compensation link of the subway traction transmission system, thereby inhibiting the unstable oscillation of the direct current side. The invention adopts a vibration suppression strategy based on selective virtual harmonic resistance, and the compensation parameters are introduced to ensure that the system just meets the stability criterion condition of the characteristic equation, so the invention can effectively suppress the instability oscillation and improve the stability of the system.
Description
Technical Field
The invention belongs to the technical field of unstable oscillation suppression of a direct current side of an urban rail direct-alternating current traction transmission system, and particularly relates to an oscillation suppression method and system based on a selective virtual harmonic resistor.
Background
As each main city in China is continuously invested in urban rail traffic construction and operation, the stability of a subway traction transmission system is continuously closely concerned, and the oscillation suppression strategy becomes a research hotspot. The core power of the subway train comes from a subway traction transmission system, and the stability of the system is related to the quality of subway operation. Most subway traction transmission systems are powered by a pantograph from a direct-current contact network, and power is supplied to a converter through a filter reactor and a support capacitor. However, due to the influences of vehicle-mounted capacity space, weight and other factors, the selection values of the filter inductance and the support capacitance on the direct current side are limited, so that the allowance of system stability cannot meet all working conditions, in addition, the damping of the system is greatly weakened by the negative impedance characteristics caused by the constant power characteristics of the motor, the stable range of the system is reduced, and the direct current side of the subway traction system can generate voltage continuous oscillation, so that the traction motor generates a pulsating torque component, a vehicle body device is damaged, and passenger experience is influenced. When the direct current side of the traction system is seriously oscillated, overvoltage and overcurrent protection can be even triggered, so that the traction system blocks pulses and completely loses the traction capability. Therefore, how to effectively solve the problem of direct current side oscillation of the traction system and ensure the stability of direct current voltage becomes a research hotspot of subway traffic.
In order to avoid the damage of train network oscillation and improve the stability of a subway traction transmission system, a plurality of domestic and foreign experts provide corresponding inhibition methods which can be divided into passive damping inhibition and active damping inhibition. Passive damping is a method to improve the stability of the system by designing filter parameters and adding additional damping structures. However, the addition of an additional damping structure complicates the main circuit structure, and meanwhile, the occurrence of instability is related to the main circuit parameters and the system working condition, and it is difficult to design the matching damping circuit parameters. Active damping is an inhibition method through control link compensation, and system admittance is reshaped, so that the impedance of the vehicle side is matched with that of the network side, and the active damping is widely concerned due to convenience and high efficiency. At present, a instability suppression strategy is to obtain an oscillation component of a direct current side voltage to adjust a torque loop current reference value correspondingly to meet the requirement of stability of a traction network, however, an overcompensation condition often occurs in the 'multiplication' scheme, and the dynamic and steady-state performance of a system is affected. The other instability suppression strategy acquires information of each state variable of the system, a state space equation is constructed to overcome system instability caused by negative impedance, the damping method ensures global system stability control, and vehicle parameters are difficult to acquire, so that the nonlinear control scheme is difficult to design and apply.
Disclosure of Invention
In order to overcome the technical problems of overcompensation or limited design and application of the existing instability suppression technology, the invention provides an oscillation suppression method based on a selective virtual harmonic resistor, so that voltage and current on the side of a traction network are stabilized, the input impedance characteristic of a traction converter-motor is improved, and the stability of a network-vehicle system is improved.
The invention is realized by the following technical scheme:
a method and a system for oscillation suppression based on selective virtual harmonic resistance are disclosed, the method comprises the following steps:
step S1, acquiring direct current side oscillation voltage of the subway traction transmission system, and carrying out Fourier analysis on the direct current side oscillation voltage to obtain oscillation frequency; constructing a instability suppression system based on the selective virtual harmonic resistance according to the selective virtual harmonic resistance suppression strategy and a direct-current side equivalent circuit of the subway traction transmission system;
step S2, according to the characteristic equation based on the selective virtual harmonic resistance instability suppression system constructed in the step S1 and according to a system progressive stability criterion, calculating to obtain voltage compensation parameters under a synchronous rotation coordinate system meeting the stability criterion condition;
and step S3, inputting the calculated voltage compensation parameters under the synchronous rotation coordinate system into a compensation link of the subway traction transmission system, thereby inhibiting the unstable oscillation of the direct current side.
The invention adopts a vibration suppression strategy based on selective virtual harmonic resistance, and the compensation parameters are introduced to ensure that the system just meets the stability criterion condition of the characteristic equation, so the invention can effectively suppress the instability oscillation and improve the stability of the system.
Preferably, the construction process of the selective virtual harmonic resistance based instability suppression system in step S1 of the present invention includes:
step S11, according to the vibration frequency of the direct current side oscillation voltage, adopting a notch filter structure with corresponding frequency;
step S12, performing selective virtual harmonic resistance compensation on the feedforward voltage component to obtain:
in the formula, alphasdAnd alphasqDq-axis voltage compensation coefficients, respectively; esdAnd EsqDq-axis feedforward voltage components, respectively;
and
respectively adding the dq axis feedforward voltage components supplemented by the selective virtual filter resistor;
Gtrap(s) a notch filter for the corresponding frequency;
is a DC side voltage oscillation component, VdcMeasuring voltage for direct current;
step S13, establishing a resistance control system based on selective virtual harmonic, the system state equation is:
in the formula (I), the compound is shown in the specification,
and
the dq-axis modulation voltage, i, respectively, being compensated for by adding a feedforward voltagesd、isqDq-axis current components, L equivalent inductance, R equivalent resistance, C direct-current side capacitance, igIs a net side current, EgIs the supply voltage, Vdc0The average value of the direct current voltage is obtained;
step S14, consider near the steady state operating point of the system
Then the system characteristic equation is obtained as:
in the formula, p0To compensate for the parameters.
Preferably, in step S1 of the present invention, the process of constructing the selective virtual harmonic based resistance instability suppression system further includes:
step S15, according to different oscillation frequencies, a virtual harmonic resistance is selectively constructed through a wave trap, active damping compensation is carried out aiming at the frequency with insufficient stability margin, and p is made0Is composed of
The obtained compensated system characteristic equation is as follows:
wherein beta is a normal number, and beta is more than or equal to 1.
Preferably, step S2 of the present invention specifically includes:
step S21, according to the system gradual stability criterion, the p is obtained by combining the compensated system characteristic equation0The following boundary conditions should be met:
in the formula, PLRepresenting the output power of the asynchronous motor;
step S22, according to the compensation parameter p0Is determined, the compensation parameter p is selected according to the requirements of the stability of the actual system0And a dq-axis voltage compensation coefficient alpha is calculated by the following formulasdAnd alphasq：
In the formula, vsd、vsqDq-axis voltage components, respectively; i.e. isd、isqRespectively, dq-axis current components.
On the other hand, the invention also provides an oscillation suppression system based on the selective virtual harmonic resistor, which comprises a instability suppression system construction module, a voltage compensation parameter calculation module and an output module;
the instability suppression system building module is used for obtaining the direct current side oscillation voltage of the subway traction transmission system and obtaining the oscillation frequency by carrying out Fourier analysis on the direct current side voltage; constructing a instability suppression system based on the selective virtual harmonic resistance according to the selective virtual harmonic resistance suppression strategy and a direct-current side equivalent circuit of the subway traction transmission system;
the voltage compensation parameter calculation module is used for calculating and obtaining voltage compensation parameters under a synchronous rotation coordinate system meeting the stability criterion condition according to a characteristic equation based on the selective virtual harmonic resistance instability suppression system and constructed by the instability suppression system construction module and a system gradual stability criterion;
and the output module is used for outputting the calculated voltage compensation parameters under the synchronous rotating coordinate system to a compensation link of a subway traction transmission system, so that the unstable oscillation of the direct current side is inhibited.
Preferably, the instability suppression system building module comprises a selection unit, a feedforward voltage compensation unit, a system state unit and a system characteristic unit;
the selection unit selects a notch filter structure with corresponding frequency according to the vibration frequency of the direct-current side oscillation voltage;
the feedforward voltage compensation unit carries out selective virtual harmonic resistance compensation on the feedforward voltage component to obtain:
in the formula, alphasdAnd alphasqDq-axis voltage compensation coefficients, respectively; esdAnd EsqDq-axis feedforward voltage components, respectively;
and
respectively adding the dq axis feedforward voltage components supplemented by the selective virtual filter resistor;
Gtrap(s) a notch filter for the corresponding frequency selected by the selection unit;
is a DC side voltage oscillation component, VdcMeasuring voltage for direct current;
the system state unit is used for establishing a resistance control system based on selective virtual harmonics, and a system state equation is as follows:
in the formula (I), the compound is shown in the specification,
and
the dq-axis modulation voltage, i, respectively, being compensated for by adding a feedforward voltagesd、isqDq-axis current components, L equivalent inductance, R equivalent resistance, C direct-current side capacitance, igIs a net side current, EgIs the supply voltage, Vdc0The average value of the direct current voltage is obtained;
the system characteristic unit is used for considering near the steady-state working point of the system
The obtained system characteristic equation is as follows:
in the formula, p0To compensate for the parameters.
Preferably, the instability suppression system building module further comprises an active damping compensation unit;
the active damping compensation unit selectively constructs a virtual harmonic resistance through a wave trap according to different oscillation frequencies, and carries out active damping compensation aiming at the frequency with insufficient stability margin so as to enable p0Is composed of
The obtained compensated system characteristic equation is as follows:
wherein beta is a normal number, and beta is more than or equal to 1.
Preferably, the voltage compensation parameter calculation module of the present invention includes a boundary condition acquisition unit and a calculation unit;
the boundary condition acquisition unit obtains p by combining a compensated system characteristic equation according to a system progressive stability criterion0The following boundary conditions should be met:
in the formula, PLRepresenting the output power of the asynchronous motor;
the calculation unit depends on the compensation parameter p0Is determined, the compensation parameter p is selected according to the requirements of the stability of the actual system0And a dq-axis voltage compensation coefficient alpha is calculated by the following formulasdAnd alphasq：
In the formula, vsd、vsqDq-axis voltage components, respectively; i.e. isd、isqRespectively, dq-axis current components.
The invention has the following advantages and beneficial effects:
according to the oscillation suppression strategy based on the selective virtual harmonic resistor, the compensation parameters are introduced, and the system just meets the characteristic equation stability criterion condition, so that the voltage and current on the traction network side are stable, the input impedance characteristic of a traction converter-motor is improved, and the stability of a network-vehicle system is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a schematic flow chart of the method of the present invention.
Fig. 2 is a schematic block diagram of the system of the present invention.
Fig. 3 is a diagram of a subway traction drive system.
Fig. 4 simplifies the equivalent circuit for the dc-ac traction drive system.
FIG. 5 is a selective virtual harmonic resistance equivalent diagram.
FIG. 6 a selective virtual harmonic resistance control strategy.
FIG. 7 is a block diagram of system stability control based on selective virtual harmonic resistance.
FIG. 8 is a DC side voltage simulation verification diagram of the present invention.
FIG. 9 is a net side current simulation verification diagram of the present invention.
Fig. 10 is a simulation verification diagram of the motor rotation speed of the present invention.
Fig. 11 is a motor torque simulation verification diagram of the present invention.
FIG. 12 is a diagram of a drive train oscillation waveform drawn by hardware on a ring platform.
The hardware of fig. 13 stabilizes the operating waveform after ring platform virtual impedance suppression.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Example 1
The present embodiment proposes an oscillation suppression method based on selective virtual harmonic resistance, as shown in fig. 1, the method of the present embodiment includes the following steps:
step S1, acquiring direct current side oscillation voltage of the subway traction transmission system, and carrying out Fourier analysis on the direct current side oscillation voltage to obtain oscillation frequency; and constructing a selective virtual harmonic resistance-based instability suppression system according to a selective virtual harmonic resistance suppression strategy and a direct-current side equivalent circuit of the subway traction transmission system. The specific construction process is as follows:
according to dq axis current component i after Park transformationsd、isqFrequency of motor omegasFeedforward voltage component EsdAnd EsqIs calculated as
Wherein R issFor stator resistance, σ ═ 1-Lm 2/LsLr，LsIs a stator inductance, LrIs the rotor inductance, LmFor exciting the inductance, EsdAnd EsqFor feedforward voltage components, ωsFor synchronous angular frequency of the motor, isd、isqIs the dq axis current component.
According to the oscillating component of the DC side voltage
Using a notch filter structure for the corresponding frequency
Wherein ω isnIs the notch angular frequency; q is a quality factor. By selective virtual harmonic resistance compensation by means of feed-forward voltage
Wherein
αsdAnd alphasqRespectively, dq-axis voltage compensation coefficient, Esd *And Esq *Is a reference value for the feedforward voltage component.
Under the synchronous rotating dq coordinate system, the output power of the asynchronous motor can be expressed by dq axis voltage current under the rotating coordinate system
PL＝vsdisd+vsqisq (3)
Wherein v issdAnd vsqAre respectively asdq-axis voltage, Esd *And Esq *Reference value, P, for the feedforward voltage componentLAnd outputting power for the motor.
The combination formula (3) is used for establishing a system state equation based on selective virtual harmonic resistance control by combining the dynamic process of direct-current side voltage and current according to a system main circuit equation
Wherein v issdA and vsqThe dq axis modulation voltage compensated by the feedforward voltage is added, L is equivalent inductance, R is equivalent resistance, C is direct current side capacitance, igIs a net side current, EgIs the supply voltage, Vdc0Is the average value of the direct current voltage,
is a direct current side voltage oscillation component;
taking into account near the steady state operating point of the system
The system characteristic equation is
In the formula p0To compensate for the parameter, Rp0/Vdc0The term is smaller and usually negligible, wherein
Wherein: alpha is alphasdAnd alphasqThe dq-axis voltage compensation coefficients, respectively.
When the subway is in traction operation, the voltage compensation coefficient alphasdAnd alphasqWhen increasing, p0Also increases, the stability margin of the system is larger,different compensation effects can be obtained by selecting different compensation parameter values.
According to different oscillation frequencies, a virtual harmonic resistance is selectively constructed through a wave trap, and active damping is performed on the frequency with insufficient stability margin. Can make p0The formula (7) is shown, wherein the parameter value is beta is more than or equal to 1, and the compensated system characteristic equation is (8).
Wherein beta is a normal number, and beta is more than or equal to 1.
And step S2, calculating voltage compensation parameters meeting the stability criterion condition under the synchronous rotation coordinate system according to the characteristic equation based on the selective virtual harmonic resistance instability suppression system constructed in the step S1 and the system progressive stability criterion. The specific calculation process is as follows:
according to the criterion of system progressive stability, combining the compensated system characteristic equation (8), p0Should satisfy
According to the compensation parameter p0With reference to the boundary condition value of the actual system stability, a compensation parameter p is selected0And substituting the value into equation (6) to obtain a dq-axis voltage compensation coefficient alphasdAnd alphasq。
And step S3, inputting the calculated voltage compensation parameters under the synchronous rotation coordinate system into a compensation link of the subway traction transmission system, thereby inhibiting the unstable oscillation of the direct current side.
Example 2
Based on the foregoing embodiments, the present embodiment provides an oscillation suppression system based on a selective virtual harmonic resistor, and as shown in fig. 2, the system of the present embodiment includes a instability suppression system construction module, a voltage compensation parameter calculation module, and an output module.
The instability suppression system construction module is used for acquiring direct-current side oscillation voltage of the subway traction transmission system and obtaining oscillation frequency by carrying out Fourier analysis on the direct-current side voltage; and constructing a selective virtual harmonic resistance-based instability suppression system according to a selective virtual harmonic resistance suppression strategy and a direct-current side equivalent circuit of the subway traction transmission system.
As shown in fig. 2, the instability suppression system building block of the present embodiment includes a selection unit, a feedforward voltage compensation unit, a system state unit, a system characteristic unit, and an active damping compensation unit.
The selection unit of the present embodiment selects a notch filter structure using a corresponding frequency according to the oscillation frequency of the dc side oscillation voltage, the notch filter structure being as described in embodiment 1 above.
The feedforward voltage compensation unit of the present embodiment performs selective virtual harmonic resistance compensation on the feedforward voltage component, which is expressed as the compensated feedforward voltage equation shown in formula (2) in embodiment 1 above.
The system state unit of the present embodiment is used to establish a selective virtual harmonic resistance-based control system, and the system state equation is as shown in the formula (4) in the above embodiment 1.
The system characteristic unit of the embodiment is used for considering near the steady-state operating point of the system
The system characteristic equation shown in the above formula (5) in example 1 was obtained.
The dynamic damping compensation unit of the embodiment selectively constructs a virtual harmonic resistor through the wave trap according to different oscillation frequencies, and performs active damping compensation aiming at the frequency with insufficient stability margin to enable p0Is composed of
To obtain the compensation shown as formula (8) in the above example 1The latter system characteristic equation.
The voltage compensation parameter calculation module of the embodiment is used for calculating and obtaining the voltage compensation parameters under the synchronous rotation coordinate system meeting the stability criterion condition according to the characteristic equation based on the selective virtual harmonic resistance instability suppression system constructed by the instability suppression system construction module and the system gradual stability criterion.
As shown in fig. 2, the voltage compensation parameter calculation module of the present embodiment includes a boundary condition acquisition unit and a calculation unit.
The boundary condition obtaining unit of this embodiment obtains p by combining the compensated system characteristic equation according to the system progressive stability criterion0The following boundary conditions should be met:
in the formula, PLRepresenting output power, p, of asynchronous machine0To compensate for the parameter, Vdc0The average value of the direct current voltage is obtained.
The calculating unit of this embodiment obtains the compensation parameter p according to the boundary condition0Is determined, the compensation parameter p is selected according to the requirements of the stability of the actual system0And a dq-axis voltage compensation coefficient alpha is calculated by the following formulasdAnd alphasq：
In the formula, vsd、vsqDq-axis voltage components, respectively; i.e. isd、isqRespectively, are dq-axis current components, alphasdAnd alphasqThe dq-axis voltage compensation coefficients, respectively.
The output module of the embodiment is used for outputting the calculated voltage compensation parameters under the synchronous rotating coordinate system to a compensation link of a subway traction transmission system, so that the unstable oscillation of the direct current side is restrained.
Example 3
The selective virtual harmonic resistance-based oscillation suppression method and system provided by the embodiment are subjected to simulation testing, and based on a hardware structure RT-LAB hardware-in-loop test platform of a DSP controller with the model number of TMS320F 28335.
Fig. 3 is a structural diagram of a subway traction transmission system, which can be simplified into a direct-alternating traction transmission system as shown in fig. 4 to simplify an equivalent circuit. The method comprises the steps of obtaining the oscillation voltage on the direct current side of the subway traction transmission system, obtaining the oscillation frequency through Fourier analysis, and constructing a selective virtual harmonic resistance instability suppression system according to a selective virtual harmonic resistance equivalent diagram shown in fig. 5, a selective virtual harmonic resistance control strategy shown in fig. 6 and a direct current side equivalent circuit of the subway traction transmission system to obtain a system stability control block diagram based on the selective virtual harmonic resistance shown in fig. 7.
The simulation wave form diagram when the motor rotating speed is stabilized at 2100r/min is shown in fig. 8-11 when the load torque is given to 600 N.m. Waveforms of the dc side voltage, the grid side current, the motor speed and the motor torque are shown from top to bottom. The left side of the central vertical dotted line in the figure is the control effect after compensation is added, and the figure shows that after the instability suppression is removed, the system gradually unstably oscillates, and the direct current voltage and the current both have obvious oscillation. From the previous analysis, when p is0＝-PL/λVdc0In the process, the introduction of the compensation parameters enables the system to just meet the stability criterion condition of the characteristic equation, and the instability oscillation suppression effect is shown in figures 8-11.
Fig. 12 is a waveform diagram of an accelerated traction test in a traction drive system without a destabilization suppression control strategy, the output power of a traction inverter is gradually increased along with the increase of the rotation speed of a motor, and when the rotation speed of the motor reaches 1300r/min, a grid-vehicle system is in divergent oscillation, wherein the maximum amplitudes of voltage and current on a direct current side are 750V and 800A respectively, and the frequency is about 30 Hz. Once the continuous oscillation occurs in an actual traction transmission system, overvoltage and overcurrent protection of a traction converter is easily caused, and then pulses are blocked to enable a train to lose power. As can be seen from the waveform diagrams 13 before and after the instability suppression control is applied, the oscillation of the direct current side of the system in the full-speed domain range is well suppressed, and therefore the correctness and the effectiveness of the instability suppression control scheme are verified.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (8)
1. An oscillation suppression method based on selective virtual harmonic resistance is characterized by comprising the following steps:
step S1, acquiring oscillation voltage on the direct current side of the subway traction transmission system, and obtaining oscillation frequency through Fourier analysis; constructing a instability suppression system based on the selective virtual harmonic resistance according to the selective virtual harmonic resistance suppression strategy and a direct-current side equivalent circuit of the subway traction transmission system;
step S2, according to the characteristic equation based on the selective virtual harmonic resistance instability suppression system constructed in the step S1 and according to a system progressive stability criterion, calculating to obtain voltage compensation parameters under a synchronous rotation coordinate system meeting the stability criterion condition;
and step S3, inputting the calculated voltage compensation parameters under the synchronous rotation coordinate system into a compensation link of the subway traction transmission system, thereby inhibiting the unstable oscillation of the direct current side.
2. The method for suppressing oscillation based on selective virtual harmonic resistance according to claim 1, wherein the step S1 of constructing the selective virtual harmonic resistance based instability suppression system includes:
step S11, according to the vibration frequency of the direct current side oscillation voltage, adopting a notch filter structure with corresponding frequency;
step S12, performing selective virtual harmonic resistance compensation on the feedforward voltage component to obtain:
in the formula, alphasdAnd alphasqDq-axis voltage compensation coefficients, respectively; esdAnd EsqDq-axis feedforward voltage components, respectively;
and
respectively adding the dq axis feedforward voltage components supplemented by the selective virtual filter resistor;
Gtrap(s) a notch filter for the corresponding frequency;
is a DC side voltage oscillation component, VdcIs a direct current side voltage;
step S13, establishing a resistance control system based on selective virtual harmonic, the system state equation is:
in the formula (I), the compound is shown in the specification,
and
the dq-axis modulation voltage, i, respectively, being compensated for by adding a feedforward voltagesd、isqDq-axis current components, L equivalent inductance, R equivalent resistance, C direct-current side capacitance, igIs a net side current, EgIs a voltage of the power supply and is,Vdc0the average value of the direct current voltage is obtained;
step S14, consider near the steady state operating point of the system
Then the system characteristic equation is obtained as:
in the formula, p0To compensate for the parameters.
3. The method for suppressing oscillation based on selective virtual harmonic resistance according to claim 2, wherein the step S1 of constructing the system for suppressing instability based on selective virtual harmonic resistance further includes:
step S15, according to different oscillation frequencies, a virtual harmonic resistance is selectively constructed through a wave trap, active damping compensation is carried out aiming at the frequency with insufficient stability margin, and p is made0Is composed of
The obtained compensated system characteristic equation is as follows:
wherein beta is a normal number, and beta is more than or equal to 1.
4. The method for suppressing oscillation based on selective virtual harmonic resistance according to claim 3, wherein the step S2 specifically comprises:
step S21, according to the system gradual stability criterion, the p is obtained by combining the compensated system characteristic equation0The following boundary conditions should be met:
in the formula, PLRepresenting the output power of the asynchronous motor;
step S22, according to the compensation parameter p0Is determined, the compensation parameter p is selected according to the requirements of the stability of the actual system0And a dq-axis voltage compensation coefficient alpha is calculated by the following formulasdAnd alphasq：
In the formula, vsd、vsqDq-axis voltage components, respectively; i.e. isd、isqRespectively, dq-axis current components.
5. An oscillation suppression system based on selective virtual harmonic resistance is characterized by comprising a instability suppression system construction module, a voltage compensation parameter calculation module and an output module;
the instability suppression system construction module is used for acquiring the oscillating voltage of the direct current side of the subway traction transmission system and obtaining the oscillating frequency through Fourier analysis; constructing a instability suppression system based on the selective virtual harmonic resistance according to the selective virtual harmonic resistance suppression strategy and a direct-current side equivalent circuit of the subway traction transmission system;
the voltage compensation parameter calculation module is used for calculating and obtaining voltage compensation parameters under a synchronous rotation coordinate system meeting the stability criterion condition according to a characteristic equation based on the selective virtual harmonic resistance instability suppression system and constructed by the instability suppression system construction module and a system gradual stability criterion;
and the output module is used for outputting the calculated voltage compensation parameters under the synchronous rotating coordinate system to a compensation link of a subway traction transmission system, so that the unstable oscillation of the direct current side is inhibited.
6. The selective virtual harmonic resistance based oscillation suppression system according to claim 5, wherein the instability suppression system construction module comprises a selection unit, a feedforward voltage compensation unit, a system state unit and a system characteristic unit;
the selection unit selects a notch filter structure with corresponding frequency according to the vibration frequency of the direct-current side oscillation voltage;
the feedforward voltage compensation unit carries out selective virtual harmonic resistance compensation on the feedforward voltage component to obtain:
in the formula, alphasdAnd alphasqDq-axis voltage compensation coefficients, respectively; esdAnd EsqDq-axis feedforward voltage components, respectively;
and
respectively adding the dq axis feedforward voltage components supplemented by the selective virtual filter resistor;
Gtrap(s) a notch filter for the corresponding frequency selected by the selection unit;
is a DC side voltage oscillation component, VdcMeasuring voltage for direct current;
the system state unit is used for establishing a resistance control system based on selective virtual harmonics, and a system state equation is as follows:
in the formula (I), the compound is shown in the specification,
and
the dq-axis modulation voltage, i, respectively, being compensated for by adding a feedforward voltagesd、isqDq-axis current components, L equivalent inductance, R equivalent resistance, C direct-current side capacitance, igIs a net side current, EgIs the supply voltage, Vdc0The average value of the direct current voltage is obtained;
the system characteristic unit is used for considering near the steady-state working point of the system
The obtained system characteristic equation is as follows:
in the formula, p0To compensate for the parameters.
7. The selective virtual harmonic resistance based oscillation suppression system according to claim 6, wherein the instability suppression system construction module further comprises an active damping compensation unit;
the active damping compensation unit selectively constructs a virtual harmonic resistance through a wave trap according to different oscillation frequencies, and carries out active damping compensation aiming at the frequency with insufficient stability margin so as to enable p0Is composed of
The obtained compensated system characteristic equation is as follows:
wherein beta is a normal number, and beta is more than or equal to 1.
8. The system according to claim 7, wherein the voltage compensation parameter calculation module comprises a boundary condition acquisition unit and a calculation unit;
the boundary condition acquisition unit obtains p by combining a compensated system characteristic equation according to a system progressive stability criterion0The following boundary conditions should be met:
in the formula, PLRepresenting the output power of the asynchronous motor;
the calculation unit depends on the compensation parameter p0Is determined, the compensation parameter p is selected according to the requirements of the stability of the actual system0And a dq-axis voltage compensation coefficient alpha is calculated by the following formulasdAnd alphasq：
In the formula, vsd、vsqDq-axis voltage components, respectively; i.e. isd、isqRespectively, dq-axis current components.
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