JP2002223570A - Margin angle control device for separately-excited converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure appropriate margin angle, and to surely prevent severe malfunctions for a converter, such as commutation failure, etc., system faults, etc. SOLUTION: This is an open-loop control system margin angle control device which executes calculation, on the basis of DC current in a DC circuit, AC voltage in an AC circuit, a commutating reactance, and a margin angle, and outputs its computation result as a control angle (control delay angle or control lead angle) for thyristor valves, in a controller for a separately excited converter 1, which is composed of an anode reactor 4 and a thyristor bridge 3 formed by bridge-connecting thyristor valves, has an AC circuit formed by connecting its AC side to an AC system 11 through a transformer 2 for a converter, and a DC circuit formed by connecting its DC side to the other terminal 5. The margin angle controller is provided with means 300, 301 for calculating the impedance value of an anode reactor 4 on the basis of the DC current of the DC circuit, and adding the impedance value to the impedance value of the transformer 2, and the added value of the transformer 2, and the added value is used as a commutation reactance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separately-excited conversion device used for a DC power transmission and frequency conversion device, for example.
Regarding the margin angle control device controlled by the open loop control system, an appropriate margin angle is particularly secured so that severe abnormalities and system accidents can be reliably prevented as a conversion device such as commutation failure. The present invention relates to a margin angle control device of a separately excited conversion device.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing an example of the general configuration of a conventional separately-excited converter of this type and its control device.

In FIG. 4, a separately-excited converter 1 comprises a thyristor bridge 3 in which three-phase thyristor valves are connected in a bridge manner and three anode reactors 4.
The AC side is connected to an AC system 11 via a converter transformer 2 to form an AC circuit, and the DC side is connected to another terminal 5 via a smoothing reactor 12 to form a DC circuit.

On the other hand, a control device 9 comprises a valve winding voltage detector 6 for detecting a line voltage of the thyristor valve winding, which is an AC voltage of the AC circuit, and a DC current detector for detecting a DC current of the DC circuit. 7, a predetermined calculation is performed by using the valve winding voltage Ei, the DC current Id, and the DC voltage Ed, which are the outputs from the DC voltage detector 8 for detecting the DC voltage of the DC circuit, as input. The control angle (control delay angle or control advance angle) α of the valve is output.

The gate pulse generator 10 generates a gate pulse based on the control angle α from the controller 9 and outputs the gate pulse to the thyristor bridge 3 of the separately-excited converter 1.

The thyristor valve winding voltage, which is the AC voltage of the AC circuit, detects the voltage on the AC side of the converter transformer 2 and converts the detected voltage into a thyristor valve winding voltage to control the control device 9. However, since the values used as a result are the same, FIG. 4 shows a configuration in which the line voltage of the thyristor valve winding is directly detected.

FIG. 5 is a block diagram showing an example of the configuration of the control device 9, and the same elements as those in FIG. 4 are denoted by the same reference numerals.

Although the configuration of the control device 9 slightly differs depending on the system, FIG. 5 shows an example basically used.

In FIG. 5, a control device 9 controls a direct current I
DC current control circuit 100 that receives d, performs feedback control, and outputs DC current control output ACRα
And a DC voltage control circuit 101 which receives a DC voltage Ed as input and performs a feedback control to output a DC voltage control output AVRα, and a DC current Id and a valve winding voltage Ei as inputs and performs a calculation to perform a margin angle control. A margin angle control circuit 102 for outputting an output AGRα, and a DC current output ACR
α, DC voltage output WRα and margin angle control output AGRα
And a control angle selecting circuit 103 for outputting a control angle (a control delay angle or a control advance angle) α.

The margin angle control circuit 102 shown in FIG. 5 is a margin angle control of an open loop control system for calculating a margin angle control output AGRα from the DC current Id and the valve winding voltage Ei.

FIG. 6 is a block diagram showing a configuration example of the margin angle control circuit 102. The same elements as those in FIG. 5 are denoted by the same reference numerals.

In FIG. 6, the margin angle control circuit 102 includes:
The DC current Id, the valve winding voltage Ei, the commutation reactance set value 201 and the allowance angle reference 202 are input to the open-loop allowance angle control circuit 200 as set values, and are generally known as follows. Is calculated with the margin angle γ and the control angle α based on the following relational expression (1), and the margin angle control output AGRα
Is output.

Note that, between the control angle α and the margin angle γ,
It is well known that there is a relationship as shown in (1).

√2Ei (1−COS (α)) = √2Ei (1 + COS (γ)) − Xc · Id (1) Ei: Line voltage of thyristor valve winding, Xc: Commutation reactance, Id: DC current control angle α = margin angle control output AGRα, the above relational expression
When the margin angle control output AGRα is obtained from (1), the following equation is obtained.

AGRα = COS ⁻¹ ((Xc · Id / (√2 · Ei)) − COS (γ)) (2) The open-loop margin angle control circuit 200 executes the above equation (2). Outputs the margin angle control output AGRα.

[0016]

However, in the control device of the conventional separately-excited converter as described above,
The margin angle control circuit 102 described with reference to FIG. 6 has the following problem to be solved.

That is, normally, the commutation reactance Xc input to the open loop margin angle control circuit 200 sets the impedance of the converter transformer 2 of FIG. 4 as a fixed value to the commutation reactance setting value 201 of FIG. Used.

On the other hand, the actual commutation reactance is determined by the impedance of the converter transformer 2 and the impedance of the anode reactor 4 in FIG.

Since a supersaturated reactor is generally used for the anode reactor 4, the impedance is large when the current is small, and the impedance is small when the current is large.

Thus, when the commutation reactance setting value 201 shown in FIG. 6 is a fixed value, the margin angle control output AGRα tends to be too small when the current is small, and the margin angle control output AGRα becomes too large when the current is large. Become a trend.

As a result, when the margin angle control output AGRα is not properly output, if a commutation failure occurs, the separately-excited converter 1 is stressed and may be damaged in some cases.

Further, the reactive power output from the separately-excited converter 1 increases due to the commutation failure, and a serious accident may occur in the equipment connected to the same AC system 11 as the separately-excited converter 1. There is.

An object of the present invention is to secure an appropriate margin angle,
It is an object of the present invention to provide a high-performance marginal-angle control device of a separately-excited conversion device capable of reliably preventing a severe abnormality and a system accident from occurring as a conversion device such as a commutation failure.

[0024]

In order to achieve the above-mentioned object, the present invention comprises an anode reactor and a thyristor bridge in which a thyristor valve is connected in a bridge, and the AC side is connected to an AC system via a transformer for a converter. A control device of a separately-excited converter that forms a circuit and connects the DC side to another terminal to form a DC circuit, based on the DC current of the DC circuit, the AC voltage of the AC circuit, the commutation reactance, and the margin angle. In a margin angle control device of an open loop control system for performing a calculation and outputting the calculation result as a control angle (a control delay angle or a control advance angle) of the thyristor valve, the DC current of the DC circuit Calculates the impedance value of the anode reactor based on the above, and adds the impedance value to the impedance value of the transformer for the converter Comprising means that, the added value, and used as the commutation reactance.

Therefore, in the margin angle control device of the separately-excited converter according to the first aspect of the present invention, the impedance value of the anode reactor calculated based on the DC current of the DC circuit is converted to the impedance value of the transformer for the converter. The added value is used as the commutation reactance in the open-loop margin angle control, so that the value of the commutation reactance is determined by the current flowing to the separately-excited converter. The output value of the open-loop margin angle control can be made appropriate without excessive or insufficient flow reactance, and an accident of the separately-excited conversion device such as commutation failure can be prevented. Further, as means for calculating the impedance value of the anode reactor based on the DC current of the DC circuit, the existing DC current detection means originally required for controlling the separately-excited converter is used, so that the DC current of the DC circuit is detected. However, there is no need to separately receive a dedicated detecting means.

In the invention corresponding to claim 2, there is provided means for calculating an impedance value of the anode reactor based on an alternating current of the alternating current circuit, and adding the impedance value to an impedance value of the transformer for the converter,
The added value is used as a commutation reactance.

Therefore, in the margin angle control device of the separately excited converter according to the second aspect of the present invention, the impedance value of the anode reactor calculated based on the AC current of the AC circuit is converted into the impedance value of the transformer for the converter. The added value is used as the commutation reactance in the open-loop margin angle control, so that the value of the commutation reactance is determined by the current flowing to the separately-excited converter. The output value of the open-loop margin angle control can be made appropriate without excessive or insufficient flow reactance, and an accident of the separately-excited conversion device such as commutation failure can be prevented.

Further, the invention according to claim 3 further comprises means for calculating a commutation reactance based on the DC voltage of the DC circuit, the DC current of the DC circuit, the control angle of the thyristor valve, and the AC voltage of the AC circuit. The calculated commutation reactance is used as a commutation reactance.

Therefore, in the margin angle control device of the separately-excited converter according to the third aspect of the present invention, the DC voltage of the DC circuit, the DC current of the DC circuit, the control angle of the thyristor valve, and the AC voltage of the AC circuit are controlled. The commutation reactance calculated based on the commutation reactance is used in the open-loop margin angle control as the commutation reactance, so that the value of the commutation reactance is determined by the current flowing to the separately-excited converter, so that an appropriate margin angle is secured and control is performed. Therefore, the output value of the open-loop margin angle control can be made appropriate, and an accident of the separately-excited conversion device such as a commutation failure can be prevented. Also, by using the commutation reactance calculated based on the DC voltage of the DC circuit, the DC current of the DC circuit, the control angle of the thyristor valve, and the AC voltage of the AC circuit as the commutation reactance in the open-loop margin angle control, Since the commutation reactance is obtained in consideration of the entire DC circuit and AC circuit of the separately-excited converter, the control accuracy can be improved as compared with the first and second aspects of the present invention.

Here, in particular, as the AC voltage of the AC circuit, a line voltage of the thyristor valve winding or a voltage on the AC side of the converter transformer is detected, and the detected voltage is converted to a thyristor valve winding voltage. It is preferable to use the converted voltage.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing an example of the configuration of a margin angle control device of a separately-excited converter according to the present embodiment. The description thereof is omitted, and only different portions will be described here.

That is, in the margin angle control device of the separately-excited converter according to the present embodiment, as shown in FIG. 1, a commutation reactance correction signal output circuit 300 and an adder circuit 301 are added to FIG. It has a configuration.

Commutation reactance correction signal output circuit 300
Receives the DC current Id of the DC circuit, which is the output from the DC current detector 7, as an input, and determines the impedance value XcAL of the anode reactor 4 based on the DC current Id.
Is calculated.

The addition circuit 301 adds the impedance value XcAL calculated by the commutation reactance correction signal output circuit 300 to the impedance value of the converter transformer 2 which is the commutation reactance setting value 201, and outputs the result.

The value added by the adding circuit 301 is input to the open loop margin angle control circuit 200 as a commutation reactance Xc.

Next, the operation of the margin angle control device of the separately-excited converter according to the present embodiment configured as described above will be described.

In FIG. 1, a commutation reactance correction signal output circuit 300 outputs an impedance XcAL of the anode reactor 4 by an approximate function or the like by inputting a DC current Id.

In the commutation reactance set value 201, the impedance of the transformer for converter 2 is set.

The addition circuit 301 includes an anode reactor 4
Impedance XcAL and commutation reactance set value 2
01 and outputs the added value as a commutation reactance Xc.

The open loop margin angle control circuit 200 receives the DC current Id, the valve winding voltage Ei, the commutation reactance Xc output from the addition circuit 301, and the margin angle γ as the margin angle reference 202, and receives the margin angle. The control output AGRα is output.

Next, such a point will be described more specifically.

That is, the impedance characteristic of the anode reactor 4 is determined by the current flowing through the anode reactor 4 and the time during which the current flows.

The maximum value of the current flowing through anode reactor 4 is the same as DC current Id.

The flowing time is a time during which the separately-excited converter 1 is commutating, that is, a current flows for a period of 120 ° in electrical angle.

Normally, the period during which the current is flowing is substantially constant, so that the impedance of the anode reactor 4 is determined by the DC current Id.

From this, it is possible to calculate the impedance value of the anode reactor 4 from the DC current Id.

In this respect, in the present embodiment, a value obtained by adding the calculated impedance value XcAL of the anode reactor 4 to the impedance value of the transformer for converter 2 is used as a commutation reactance Xc of the open-loop margin angle control circuit 200. By using the input, the value of the commutation reactance Xc is determined by the current flowing through the separately-excited converter 1,
No excessive or insufficient commutation reactance used for control occurs.
The output value of the open loop margin angle control can be made appropriate,
An accident of the separately-excited converter 1 such as a commutation failure can be prevented.

As described above, in the margin angle control device of the separately-excited converter according to the present embodiment, the impedance of the anode reactor 4 that changes according to the current varies with the commutation reactance Xc used in the open-loop margin angle control circuit 200. In order to output an appropriate margin angle control output AGRα in each operation state of the separately-excited converter 1 in the corrected state, a proper margin angle is secured, and severe abnormalities and system accidents occur as a converter such as commutation failure. Can be reliably prevented.

The DC current Id input to the commutation reactance correction signal output circuit 300 for calculating the impedance value XcAL of the anode reactor 4 based on the DC current Id of the DC circuit is originally used for controlling the separately-excited converter 1. Since the necessary output from the existing DC current detector 7 is used, there is no need to separately receive a dedicated detector for detecting the DC current Id of the DC circuit.

(Second Embodiment) FIG. 2 is a block diagram showing a configuration example of a margin angle control device of a separately-excited converter according to the present embodiment, and the same parts as those in FIG. The description thereof is omitted, and only different portions will be described here.

That is, the margin angle control device of the separately-excited conversion device according to the present embodiment, as shown in FIG.
, The commutation reactance set value 201 is omitted, and a commutation reactance calculation circuit 302 is newly provided instead.

The commutation reactance calculation circuit 302 controls the DC voltage Ed of the DC circuit output from the DC voltage detector 8, the DC current Id of the DC circuit output from the DC current detector 7, and the control of the thyristor valve. The angle α and the valve winding voltage E which is the output from the valve winding voltage detector 6
Based on i, a commutation reactance Xc is calculated.

The commutation reactance calculation circuit 3
02 to the open-loop margin angle control circuit 200.
As you type.

Next, the operation of the present embodiment configured as described above will be described.

In FIG. 2, a commutation reactance calculation circuit 302 receives a DC current Id, a valve winding voltage Ei, a control angle α, and a DC voltage Ed, and obtains the following equations (3) and (3).
By executing (4), the commutation reactance Xc is output.

The open loop margin angle control circuit 200 receives the DC current Id, the valve winding voltage Ei, the commutation reactance Xc output from the commutation reactance calculation circuit 302, and the margin angle γ as the margin angle reference 202. And outputs the margin angle control output AGRα.

Next, such a point will be described more specifically.

That is, first, the DC voltage Ed is obtained by executing the following equation (3).

Ed = 3√2 / π) · EI · COS (α) − (3 / π) Xc · Id (3) Ed: DC voltage, Ei: Valve winding voltage, α: Control angle, Xc : Commutation reactance, Id: DC current Next, the relational expression (3) of the DC voltage is expressed by the commutation reactance Xc
(4).

The following equation (4) summarizes the above equation (3) for the commutation reactance Xc.

Xc = ((3√2 / π) · Ei · COS (α) −Vd) / ((3 / π) · Id) (4) Ed: DC voltage, Ei: Valve winding voltage, α: control angle, Xc: commutation reactance, Id: DC current According to the above equation (4), the DC current Id = 0 while the separately-excited converter 1 is stopped, and the calculation result is undefined.

In this case, the problem can be solved by limiting the lower limit of the DC current Id used in the calculation of the equation (4) with the minimum current level during the operation of the separately-excited converter 1.

From this, it is possible to calculate the actual commutation reactance Xc by calculating the commutation reactance by equation (4).

In this regard, in the present embodiment, the calculated commutation reactance Xc is used as the input of the open-loop margin angle control circuit 200 as the commutation reactance Xc, so that the value of the commutation reactance Xc is separately excited. Since the current is determined by the current flowing through the device 1, the commutation reactance used for control does not become excessive or insufficient, and the output value of the open-loop margin angle control can be made appropriate. The first accident can be prevented.

As described above, in the margin angle control device of the separately-excited converter according to the present embodiment, the commutation reactance Xc is corrected by the detection signal of the operating state of the separately-excited converter 1, and In order to output the appropriate margin angle control output AGRα in each operation state, it is necessary to secure an appropriate margin angle and to surely prevent the occurrence of severe abnormalities and system accidents as a conversion device such as commutation failure. It becomes possible.

The commutation reactance Xc calculated based on the DC voltage Ed of the DC circuit, the DC current Id of the DC circuit, the control angle α of the thyristor valve, and the valve winding voltage Ei (AC voltage of the AC circuit) is calculated as follows: By using the commutation reactance in the open-loop margin angle control to obtain the commutation reactance in consideration of the entire DC circuit and AC circuit of the separately-excited converter 1, the control is performed in comparison with the case of the first embodiment. Accuracy can be improved.

(Third Embodiment) FIG. 3 is a block diagram showing an example of a configuration of a margin angle control device of a separately-excited converter according to the present embodiment. The description thereof is omitted, and only different portions will be described here.

That is, the margin angle control device of the separately-excited converter according to the present embodiment has a commutation reactance correction signal output circuit 400 and an adder circuit 401 added to FIG. 6 as shown in FIG. It has a configuration.

Commutation reactance correction signal output circuit 400
Is an AC current Iac of the AC circuit, which is an output from an AC current detector (not shown) for detecting the AC current of the AC circuit.
And the impedance value XcAL of the anode reactor 4 is calculated based on the AC current Iac.

The addition circuit 401 adds the impedance value XcAL calculated by the commutation reactance correction signal output circuit 400 to the impedance value of the converter transformer 2 which is the commutation reactance setting value 201, and outputs the result.

The value added by the adding circuit 401 is input to the open-loop margin angle control circuit 200 as a commutation reactance Xc.

Next, the operation of the marginal angle control device of the separately-excited converter according to the present embodiment configured as described above will be described.

In FIG. 3, the commutation reactance correction signal output circuit 400 outputs the impedance XcAL of the anode reactor 4 by an approximate function or the like by inputting the AC current Iac.

The impedance of the transformer for converter 2 is set in the commutation reactance set value 201.

The addition circuit 401 includes an anode reactor 4
Impedance XcAL and commutation reactance set value 2
01 and outputs the added value as a commutation reactance Xc.

The open loop margin angle control circuit 200 receives the DC current Id, the valve winding voltage Ei, the commutation reactance Xc output from the addition circuit 401, and the margin angle γ as the margin angle reference 202, and receives the margin angle. The control output AGRα is output.

In the present embodiment, the value obtained by adding the calculated impedance value XcAL of the anode reactor 4 to the impedance value of the transformer for converter 2 is input to the open-loop margin angle control circuit 200 as the commutation reactance Xc. Thus, the value of the commutation reactance Xc is determined by the current flowing through the separately-excited converter 1, so that the commutation reactance used for control does not become excessive or insufficient, and the output value of the open-loop margin angle control is made appropriate. Therefore, it is possible to prevent an accident of the separately-excited conversion device 1 such as a commutation failure.

As described above, in the margin angle control device of the separately-excited converter according to the present embodiment, the impedance of the anode reactor 4 that changes according to the current is changed to the commutation reactance Xc used in the open-loop margin angle control circuit 200. In order to output an appropriate margin angle control output AGRα in each operation state of the separately-excited converter 1 in the corrected state, a proper margin angle is secured, and severe abnormalities and system accidents occur as a converter such as commutation failure. Can be reliably prevented.

[0080]

As described above, according to the margin angle control device of the separately-excited converter of the present invention, the impedance of the anode reactor is appropriately compensated for the commutation reactance used in the open-loop margin angle control. The angle of margin of a high-performance separately-excited converter that can secure an appropriate margin angle and reliably prevent the occurrence of severe abnormalities and system accidents as a converter such as commutation failure A control device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a margin angle control device of a separately excited conversion device according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of a margin angle control device for a separately-excited converter according to the present invention.

FIG. 3 is a block diagram showing a third embodiment of a margin angle control device for a separately-excited converter according to the present invention.

FIG. 4 is a block diagram showing an overall configuration example of a conventional separately-excited conversion device and a control device thereof.

FIG. 5 is a block diagram showing a configuration example of a control device in FIG. 4;

FIG. 6 is a block diagram showing a configuration example of a margin angle control circuit in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Separately-excited converter 2 ... Transformer transformer 3 ... Thyristor bridge 4 ... Anode reactor 5 ... Other terminals 6 ... Valve winding voltage detector 7 ... DC current detector 8 ... DC voltage detector 9 ... Control device 10 ... Gate pulse generator 11 ... AC system 12 ... Smoothing reactor 100 ... DC current control circuit 101 ... DC voltage control circuit 102 ... Margin angle control circuit 103 ... Control angle selection circuit 200 ... Open loop margin angle control circuit 201 ... Commutation reactance Set value 202: Margin angle reference 300: Commutation reactance correction signal output circuit 301: Addition circuit 302: Commutation reactance calculation circuit 400: Commutation reactance correction signal output circuit 401: Addition circuit Id: DC current Ed: DC voltage Ei Valve winding voltage Xc Commutation reactance γ ... margin angle reference ACRα ... DC current control output A VRα: DC voltage control output AGRα: Margin angle control output α: Control angle XcAL: Anode reactor impedance.

Claims (5)

[Claims] A thyristor bridge having a thyristor valve connected in a bridge and an anode reactor. The AC side is connected to an AC system via a transformer for a converter to form an AC circuit, and the DC side is connected to another terminal. A control device for a separately-excited converter configured as a DC circuit, performing calculations based on a DC current of the DC circuit, an AC voltage of the AC circuit, a commutation reactance, and a margin angle, and comparing the calculation result with the thyristor valve. A control angle (control delay angle or control advance angle) of the open-loop control type margin angle control device, wherein the impedance value of the anode reactor is calculated based on the DC current of the DC circuit, and the impedance value is calculated. Means for adding to the impedance value of the transformer for the converter, A margin angle control device for a separately-excited conversion device, which is used as an actance. 2. An rectifier comprising a thyristor bridge in which a thyristor valve is bridge-connected and an anode reactor. The AC side is connected to an AC system via a transformer for a converter to form an AC circuit, and the DC side is connected to another terminal. A control device for a separately-excited converter configured as a DC circuit, performing calculations based on a DC current of the DC circuit, an AC voltage of the AC circuit, a commutation reactance, and a margin angle, and comparing the calculation result with the thyristor valve. A control angle (control delay angle or control advance angle) of the open-loop control type margin angle control device, wherein the impedance value of the anode reactor is calculated based on the AC current of the AC circuit, and the impedance value is calculated. Means for adding to the impedance value of the transformer for the converter, A margin angle control device for a separately-excited conversion device, which is used as an actance. 3. An AC circuit comprising a thyristor bridge in which a thyristor valve is bridge-connected and an anode reactor, wherein the AC side is connected to an AC system via a transformer for a converter, and the DC side is connected to another terminal. A control device for a separately-excited converter configured as a DC circuit, performing calculations based on a DC current of the DC circuit, an AC voltage of the AC circuit, a commutation reactance, and a margin angle, and comparing the calculation result with the thyristor valve. A control angle (control delay angle or control advance angle) of the open-loop control method, wherein the DC voltage of the DC circuit, the DC current of the DC circuit, the control angle of the thyristor valve, and the AC Means for calculating a commutation reactance based on an AC voltage of a circuit, wherein the calculated commutation reactance is calculated by the commutation. A margin angle control device for a separately-excited conversion device, which is used as a reactance. 4. The method according to claim 1, wherein
The margin angle control device for a separately-excited converter according to the above item, wherein the AC voltage of the AC circuit is a line voltage of the thyristor valve winding, and the margin angle of the separately-excited converter is characterized in that: Control device. 5. The method according to claim 1, wherein
In the margin angle control device of the separately-excited converter according to the paragraph, as the AC voltage of the AC circuit, a voltage on the AC side of the converter transformer is detected, and the detected voltage is converted into the thyristor valve winding voltage. A margin angle control device for a separately-excited conversion device, wherein a marginal voltage control device is used.