JP2005304156A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter which can alleviate the imbalance of a current and stabilize a wiring voltage. <P>SOLUTION: This power converter has a converter which is connected via a main transformer to wiring, an inverter which is connected via a filter capacitor to the DC side of the converter, and a power computing means which computes the power of the converter or the power of the inverter. The converter makes a reactive current flow to the AC side of the converter according to the power of the converter or the inverter computed by the power computing means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a power conversion device.

In a power converter equipped with a converter and an inverter for receiving a single-phase alternating current from an overhead line and driving a main motor as in a high-speed railway vehicle such as a bullet train, if the overhead line voltage rises too much, the output voltage of the converter Saturation, overhead current distortion increases, protective action works,
Operation may be stopped. Conversely, if the overhead line voltage drops too much, it is necessary to increase the effective current in order to supply the same power to the main motor, but if this exceeds the current capacity of the converter, the power is limited, Limit the torque of the main motor. For this reason, the acceleration / deceleration of the vehicle may be lower than a predetermined value, which may disturb the operation schedule.

In order to cope with this problem, in the conventional power converter, in accordance with the overhead line voltage, a power factor or reactive power is set by the power converter so that the overhead line voltage does not rise or fall too much. The adjustment is disclosed in Patent Document 1.
Japanese Patent No. 3085406

However, since the conventional power conversion device controls the power factor according to the overhead line voltage, in the case of a railway vehicle having a normal configuration including a plurality of power conversion devices in one formation, a common pant point Since each power conversion device unit controls the overhead line voltage independently, there is a concern that the overhead line voltage may become unstable. In particular, when power converters made by multiple manufacturers with different characteristics are mounted on the same train, or when there are other trains equipped with power converters of completely different types in the same feeding section Is assumed. Even if it is not unstable, due to individual differences such as the offset of the overhead voltage detector, only a specific power conversion device always degrades the power factor (usually 1), and the reactive current increases. There is a possibility that it may occur constantly and cause the life of the power converter to be shortened.

Then, an object of this invention is to provide the power converter device which can reduce an electric current imbalance and can stabilize an overhead wire voltage.

The above-described problems include a converter connected to an overhead line via a main transformer, an inverter connected to the DC side of the converter via a filter capacitor, and power calculation means for calculating the power of the converter or the power of the inverter. The converter can be achieved by flowing a reactive current to the AC side of the converter according to the power of the converter or the inverter calculated by the power calculation means.

The above-mentioned problems include a converter connected to an overhead wire via a main transformer, an inverter connected to the DC side of the converter via a filter capacitor, means for detecting a current on the AC side of the converter, and the converter Current control means for adjusting the output voltage of the converter so that the current of the converter detected by the means for detecting the current on the alternating current side matches a predetermined current command, and power of the converter or power of the inverter And a reactive current command calculating means for calculating a reactive current command value according to the power of the converter or the inverter calculated by the power calculating means, and the current control means includes:
This can be achieved by correcting the predetermined current command value by the reactive current command calculated by the reactive current command calculating means.

The above-described problems include a converter connected to an overhead line via a main transformer, an inverter connected to the DC side of the converter via a filter capacitor, and power calculation means for calculating the power of the converter or the power of the inverter. The converter can be achieved by adjusting the power factor on the AC side of the converter according to the power of the converter or the inverter calculated by the power calculation means.

According to the present invention, it is possible to provide a power conversion device that can reduce current imbalance and stabilize the overhead line voltage.

(First embodiment)
A power converter according to a first embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a power converter according to a first embodiment of the present invention.

In the power conversion device according to the first embodiment of the present invention, single-phase AC power fed from a substation is collected by a pantograph 2 and via a main transformer 5 having three windings. Connected to the converter 11. On the DC side of the converter 11, a filter capacitor 12
And a VVVF inverter 14 for driving and controlling the main motor 15 is connected. The converter control means 16 uses the AC side current detected by the current detector 9 and the third winding 8 of the main transformer so that the filter capacitor voltage Vdc detected by the voltage detector 13 becomes a predetermined value.
The AC output voltage Vc of the converter 11 is controlled on the basis of the output of the voltage detector provided in the above. The converter control means 16 is supplied with an output current Ic that is the AC side current of the converter, a filter capacitor voltage Vdc, and a tertiary voltage Vs3 that is the voltage of the third winding of the main transformer 5. The tertiary voltage Vs3 is used as an alternative to the overhead wire voltage (punter voltage) Vp, and may be a voltage detected from the primary voltage that is the voltage of the first winding of the main transformer 5.

In the converter control means configured as described above, the zero cross detection means 27 detects the zero cross based on the tertiary voltage Vs3 corresponding to the overhead line voltage. The phase synchronization control means 28 calculates the phase θs of the power supply voltage from the zero cross point of the tertiary voltage. Here, the zero point of the phase θs is defined as the zero cross point of the tertiary voltage (punter point voltage). Voltage control means 1
9 is inputted with a deviation between the filter capacitor voltage Vdc output from the subtractor 18 and the DC voltage command Vdc * which is a target value thereof, and based on the power supply voltage phase θs so that the deviation becomes zero, The effective current command value IP * of the converter is calculated as shown in equation (1). Here, IPA * is an effective current amplitude command, and is obtained, for example, as shown in equation (2).

IP * = IPA * x sin (θs) (1)
IPA * = (KpAVR + KiAVR / s) x (Vdc *-Vdc) (2)
However, KpAVR and KiAVR are proportional gain and integral gain of DC voltage control. S is a Laplace operator.

Usually, a transformer or converter is operated with a power factor of 1 at the punter point, aiming at high efficiency, miniaturization, and weight reduction. That is, the current command is calculated by the equation (1) itself, and the reactive current command =
0.

Here, the power conversion device according to the present embodiment is characterized in that there is a process of adding and correcting the reactive current command to the current command in accordance with the DC power of the converter 11.

The power calculation means 17 calculates the power Pc of the converter 11 from the AC side current Ic of the converter 11 and a converter output voltage command Vc * described later. It is better to calculate this power so that it becomes a direct current amount, such as calculating an average power for one period rather than an instantaneous power. Here, the sign of the electric energy is defined as Pc> 0 for power running (electric power from the overhead line to the vehicle) and Pc <0 for regeneration (electric power from the vehicle to the overhead line).

The reactive current amplitude command calculation means 18 calculates and outputs a reactive current amplitude command IQA * according to the power Pc of the converter 11 that is the output of the power calculation means 17. For example, as in equation (3)
It is proportional to the converter power Pc,
IQA * = K1 × Pc (3)
(4) It can have a dead zone like a formula. Where α is the dead band set value (α> 0).

IQA * = K2 × (Pc-α) if (α <Pc) (4)
IQA * = 0 if (-α <= Pc <= α)
IQA * = K2 × (Pc + α) if (Pc <-α)
In the settings of the formulas (3) and (4), when the converter 11 is regenerative (electric power is from the vehicle to the overhead line), the increase of the overhead line voltage is suppressed, and the converter 11 is powered. In such a case, an operation for suppressing the decrease of the overhead wire voltage is performed.

The reactive current amplitude command IQA * calculated by the reactive current command calculating means 18 is input to the reactive current command calculating means 25. The reactive current command computing means 25 computes and outputs the reactive current command IQ * as shown in equation (5) based on the power supply phase θs output from the phase synchronization control means 28.

IQ * = IQA * x cos (θs) (5)
The adder 20 calculates the output current command Ic * of the converter by adding the reactive current command IQ * to the active current command IP * which is a conventional current command. The current control means 22 calculates an output voltage correction amount Vccmp as shown in equation (6) so that the detected output current Ic matches the converter output current command value Ic *.

Vccmp = KpACR (Ic * -Ic) (6)
Further, the power supply voltage FF calculation means 26 sets the feedforward term VsFF of the overhead line voltage to (7)
Calculate as in the equation. Here, Vs * is a conversion value (secondary winding rated voltage of the main transformer) of the overhead wire rated voltage (primary winding rated voltage of the main transformer) to the converter AC side.

VsFF = Vs * sin (θs) (7)
In the adder 23, the output voltage command value Vc * of the converter can be calculated by adding the overhead wire voltage feedforward term VsFF and the output voltage correction amount Vccmp. The PWM control 24 generates a gate to the converter 11 by triangular wave comparison PWM control or the like so that an output voltage that matches the output voltage command value Vc * of the converter is obtained.

The reactive current command calculating unit 25 sets a reactive current command corresponding to the preset output power according to the output power of the converter 11 calculated by the power calculating unit 17. Current controller 2
2 adjusts the output voltage of the converter so that a reactive current corresponding to the reactive current command flows (to the AC side of the converter).

Although the action of the reactive current on the overhead line voltage (punter voltage) is well known, it will be briefly described here. FIG. 2 is a system diagram from the substation to the power converter.

The overhead line system described in FIG. 2 is fed from the substation 29 via the overhead line impedance 30 and collects power via the pantograph 2 and the wheels 4 on the power converter side. The overhead line impedance 30 mainly includes a reactance L and a resistance R. Here, the current Is flowing through the overhead wire is positive in the direction flowing from the substation 29 to the vehicle.

The operation of the power conversion apparatus according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a vector diagram in the case of power running (electric power is from a substation to a vehicle). FIG.
These are vector diagrams in the case of regeneration (electric power is from a vehicle to a substation).

When the power converter according to the first embodiment of the present invention is powered, the reactive current of FIG.
For the state of 0 (power factor = 1), as shown in FIG.
Increase the overhead line voltage (punter voltage). On the other hand, during regeneration, the reactive current in FIG.
With respect to the state of (power factor = 1), by passing a delayed reactive current IsQ as shown in FIG. 4B, the overhead line voltage (punter point voltage) is decreased.

The power conversion device configured as described above is configured to reduce the overhead line voltage when the converter is regenerative (power is from the vehicle to the overhead line), and to the overhead line when power is running (from the overhead line to the vehicle). It is possible to flow a reactive current in the direction of increasing the voltage and suppress the fluctuation of the overhead line voltage.

In the power conversion device according to the present embodiment, the reactive current is set according to the power (converter power) in its own power conversion device, instead of causing the reactive current to flow according to the overhead line voltage as in the prior art. . For this reason, it is hard to produce the problem which interferes with another power converter device via an overhead wire voltage which is a concern in a prior art. Thus, it is possible to stably suppress fluctuations in the overhead line voltage without causing instability.

Power converters configured in this way can reduce overhead voltage fluctuations without causing instability due to interference with other power converters or overcurrent / life reduction due to load (reactive current) imbalance. Can be suppressed.

(Second Embodiment)
The power conversion device according to the second embodiment of the present invention is characterized in that the dead band of the reactive current amplitude command calculation means 18 is set as shown in equation (8).

IQA * = 0 if (-α <= Pc) (8)
IQA * = K3 × (Pc + α) if (Pc <-α)
In the setting described in the equation (8), the reactive current is superimposed so as to suppress the increase in the overhead line voltage during regeneration, but the increase in the overhead line voltage is not suppressed during power running. In general, the inverter 14 of the power converter is controlled so as to obtain a predetermined output of the electric motor 15 regardless of the overhead line voltage. Therefore, when the overhead wire voltage decreases in the power running state, the output current of the converter 11 originally increases. Therefore, in the setting described in the equation (8), it is assumed that the output current of the converter 11 is increased in the power running state, and in the power running state, the current value is further increased by not flowing the reactive current. I try not to cause it.

In the power conversion device configured as described above, the reactive current flows so as to suppress an increase in the overhead line voltage during regeneration, but it can be operated so as not to suppress the increase in the overhead line voltage during power running. In general, an inverter which is a load of a converter is controlled so as to obtain a predetermined motor output regardless of the overhead line voltage. Therefore, when the overhead line voltage decreases due to power running, the output current of the converter originally increases. Therefore, a delay reactive current is allowed to flow so as to suppress an increase in the overhead line voltage only for regeneration that has a high overhead line voltage and a margin in the converter output current. On the other hand, the overhead line voltage is low and the converter output current has no margin. In powering (which tends to cause overcurrent, or that would limit the inverter output, that is, the motor output due to power limitation), avoid overcurrent by not passing reactive current that may increase the current value. It is possible not to cause protection by the inverter or to limit the power on the inverter side.

In the power converters according to the first and second embodiments, the reactive current setting is determined according to the converter power, but not the converter power but the inverter power or the electric motor. It goes without saying that the same effect can be obtained even with the power of.

Moreover, in the power converters of the first embodiment and the second embodiment, the fluctuation of the overhead line voltage is suppressed by adjusting the reactive current, but even if the power factor is controlled. Similar effects can be obtained.

(Third embodiment)
A power converter according to a third embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 5 is a block diagram of a power conversion device according to a third embodiment of the present invention. In addition, FIG.
Throughout, the same structural elements as those shown in FIG.

The power conversion device according to the third embodiment based on the present invention is different from the power conversion device according to the second embodiment in input to the reactive current amplitude command calculation means 18. In the power conversion device of the second embodiment, the reactive current amplitude command calculation means 18 receives the calculated converter power, whereas the power conversion device of the present embodiment receives the tertiary voltage Vs3. The

The reactive current amplitude command calculation means 18 calculates and outputs a reactive current amplitude command IQA * as shown in equation (9). Here, Vs3Set is a voltage level at which a reactive current starts to flow.

IQA * = 0 if (Vs3 <= Vs3Set) ... 9
IQA * = K3 × (Vs3 -Vs3set) if (Vs3> Vs3Set)
Subsequent to the output of the reactive current amplitude command calculation means 18 is the same as that of the power converter of the first embodiment and the power converter of the second embodiment.

As in the second embodiment, the power conversion device configured as described above sets the reactive current according to the overhead line voltage, not according to its own power. Similarly to the power conversion device of the second embodiment, an invalid current is supplied so as to suppress an increase in the overhead line voltage during regeneration, and an increase in the overhead line voltage is not suppressed during power running. Therefore, a delay reactive current is allowed to flow so as to suppress an increase in the overhead line voltage only for regeneration that has a high overhead line voltage and a margin in the converter output current. On the other hand, the overhead line voltage is low and the converter output current has no margin. In powering (which tends to cause overcurrent, or that would limit the inverter output, that is, the motor output due to power limitation), avoid overcurrent by not passing reactive current that may increase the current value. It is possible not to cause protection by the inverter or to limit the power on the inverter side.

The power converter configured in this way is inferior to the power converters of the first and second embodiments in terms of reducing current imbalance and stabilizing the overhead line voltage. Compared with the power converter, the current imbalance can be reduced, and the overhead wire voltage is stabilized.

In the description of the present invention, it is described that the reactive current flows for the purpose of reducing the current imbalance and stabilizing the overhead line voltage. However, the power is reduced so that the same reactive current as that of the power converter according to the present invention flows. Needless to say, the power factor can be adjusted because the same effect can be obtained by adjusting the rate.

It is a block diagram of the power converter device of a 1st embodiment based on the present invention. It is a system diagram from a substation to a power converter. It is a vector diagram at the time of power running. It is a vector diagram at the time of regeneration. It is a block diagram of the power converter device of 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Overhead wire 2 ... Pantograph 3 ... Rail 4 ... Wheel 5 ... Main transformer 6 ... Primary winding 7 ... Secondary winding 8 ... Tertiary winding 9 ... Current detector 10 ... Voltage detector 11 ... Single phase converter DESCRIPTION OF SYMBOLS 12 ... Filter capacitor 13 ... Voltage detector 14 ... VVVF inverter 15 ... Main motor 16 ... Converter control means 17 ... Power calculating means 18 ... Reactive current amplitude command calculating means 19 ... DC voltage control means 20 ... Adder 21 ... Subtractor 22 ... Current control means 23 ... Adder 24 ... PWM control means 25 ... Reactive current command calculation means 26 ... Power supply voltage FF calculation means 27 ... Zero cross detection means 28 ... Phase synchronization control means 29 ... Substation 30 ... Overhead impedance

Claims (6)

A converter connected to the overhead line via the main transformer;
An inverter connected to the DC side of the converter via a filter capacitor;
Power calculating means for calculating the power of the converter or the power of the inverter,
The converter converts an invalid current to the AC side of the converter according to the power of the converter or the inverter calculated by the power calculation means. A converter connected to the overhead line via the main transformer;
An inverter connected to the DC side of the converter via a filter capacitor;
Means for detecting the current on the AC side of the converter;
Current control means for adjusting the output voltage of the converter so that the current of the converter detected by the means for detecting current on the AC side of the converter matches a predetermined current command;
Power calculating means for calculating the power of the converter or the power of the inverter;
Reactive current command calculation means for calculating a reactive current command value according to the power of the converter or the inverter calculated by the power calculation means,
The power control device, wherein the current control unit corrects the predetermined current command value by a reactive current command calculated by the reactive current command calculation unit. In the power converter according to claim 1 and claim 2,
The power converter is characterized in that a reactive current flows in a direction in which the overhead line voltage increases during power running, and a reactive current flows in a direction in which the overhead line voltage decreases during regeneration. In the power converter according to claim 1 and claim 2,
The power conversion device is characterized in that a reactive current flows in a direction in which the overhead line voltage decreases during regeneration, and a reactive current that causes a power factor of 1 to flow during power running. In the power converter according to claim 1 and claim 2,
The power converter has a means for detecting an overhead wire voltage,
When the overhead wire voltage detected by the means for detecting the overhead wire voltage is high, a reactive current is caused to flow in a direction in which the overhead wire voltage decreases, and when the overhead wire voltage is low, a reactive current is caused to flow so that the power factor becomes 1. The power converter characterized by this. A converter connected to the overhead line via the main transformer;
An inverter connected to the DC side of the converter via a filter capacitor;
Power calculating means for calculating the power of the converter or the power of the inverter,
The converter adjusts the power factor on the AC side of the converter according to the power of the converter or the inverter calculated by the power calculation means.

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