JP3457454B2 - Harmonic suppression cooperative controller for AC / DC converter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a harmonic suppression cooperative control apparatus for an AC / DC converter, which is applied to a DC power transmission system, a frequency converter, or a grid interconnection device in a power system.

[0002]

2. Description of the Related Art FIG. 7 shows the structure and control device of a general separately excited AC / DC converter. In FIG. 7, an AC busbar 1 is connected to a converter 3 composed of a thyristor bridge via a converter transformer 2. The circuit on the DC side of the converter 3 is connected to the other converter 5 via the DC reactor 4, and the AC side of the converter 5 is connected to the AC bus 7 via the converter transformer 6.

The converter 3 operates as a forward converter on the power transmission side or an inverse converter on the power receiving side, and at this time, the converter 5 operates as an inverse converter or a forward converter, respectively. Since the converter 3 and the converter 5 have the same control device, the configuration and operation of the control device 10 will be described for the converter 3. The DC voltage Ed is detected by the DC voltage detector 8, and the voltage control device 12 determines a control angle such that the DC voltage becomes a value as set.

On the other hand, the direct current I is detected by the direct current detector 9.
d is detected, and the current control device 13 determines a control angle such that the direct current becomes a value as set. Further, the AC voltage detector 11 detects the voltage of the AC bus, and the margin angle control device 14 determines a control angle for maintaining the set minimum margin angle.

The minimum control angle among the control angles output by the control devices 12 to 14 is selected by the minimum value selection device 16 and output as the final control angle α. Usually a current controller on the forward converter side
The output of 13 is selected, and the output of the voltage control device 12 or the margin control device 14 is selected on the inverse converter side by a bias circuit (not shown).

On the other hand, the AC voltage detector 11 causes the AC bus 1
Of the AC voltage is detected by the phase detector 15, and the phase angle θ is output. In the pulse generator 17, the control angle α
The pulse signal is generated by deciding the generation timing of the gate pulse given to each thyristor from the phase angle θ and the phase angle θ. As a result, the converter 3 carries out conversion between AC and DC and operates so that the above-mentioned DC current or DC voltage becomes a specified value.

By the way, in addition to the converter transformer 2 described above, the AC bus 1 consumes an AC filter 18 for absorbing harmonics generated by the converter 3 as shown in FIG. 8 and a converter 3. Phase compensation capacitor 19 for compensating reactive power
Is normally connected, and the AC bus 1 is connected to the AC system 21 via the power transmission line 20 to exchange electric power.

At this time, when the impedance of the AC circuit is observed from the AC bus 1, a parallel resonance point is found between the advanced phase components such as the AC filter 18 and the phasing capacitor 19 and the delayed phase components of the power transmission line 20 and the AC system 21. Therefore, when the impedance becomes large at this parallel resonance point and becomes extremely large, a phenomenon called harmonic instability occurs due to the interaction with the converter 3, and the converter 3 becomes It is known that it may not be possible to continue driving.

As a countermeasure against this, as shown in FIG. 9, the output signal of the DC current detector 9 is used to extract a harmonic component from the DC current, and a control circuit for setting the gain and correcting the phase. Harmonic suppression control circuit consisting of 23 and 24
It has been proposed to add the output to the controller 10 of the AC / DC converter by the adder 25.

The operation of this circuit is to extract the harmonic component of a specific order generated in the DC current when the harmonic instability occurs by the DC current detector 9 and the filter 22, and based on this signal. By manipulating the control angle α of the converter 3 with an appropriate phase and gain, the above-described harmonic component and the opposite-phase harmonic component are generated from the converter 3, and the harmonics are suppressed by canceling each other. To do.

[0011]

At the addition point of the output of the harmonic suppression control circuit 24, the limiter 26 is provided in the control device 10 of the AC / DC converter so that the converter 3 does not normally operate abnormally. Is provided at the point A in FIG. 9, and if the control angle α sticks to the upper limit or the lower limit of the limiter, even if an attempt is made to increase or decrease the control angle α, The operation in the direction sticking to will not be effective, and as a result, the effect of suppressing harmonics will be weakened.

On the other hand, if the adder 25 is provided at the point B in FIG. 9, the converter may operate at a point outside the value set by the limiter 26, so that the converter does not operate abnormally. It may not be possible to achieve the purpose of the set limiter.

The present invention has been made to solve the above-mentioned problems, and when the harmonic suppression control operates, it can cooperate with the control device of the AC / DC converter to maximize the effect. It intends to provide a harmonic suppression cooperative control device.

[0014]

A harmonic suppression cooperative control apparatus for an AC / DC converter according to claim 1 of the present invention is a control angle output from a voltage control apparatus, a control angle output from a current control apparatus, and a margin angle control. The minimum control angle output from the device is used as the final control angle output and is input to the adder together with the output from the harmonic suppression control circuit to generate a control pulse, and this pulse output controls the converter. A control device of an AC / DC converter for operating an angle, the first level detector detecting that a harmonic suppression control circuit has operated, and the control angle of the controller of the AC / DC converter is an upper limit or a lower limit of a limiter. Output of the second level detector or the output of the third level detector, the output of the first level detector and the second or third level detector for determining whether or not The other one The first and second AND circuits which respectively form AND conditions, the first and second bias setting circuits which are respectively connected to the respective AND circuits in advance and each have a closing switch, and each of the bias setting circuits. The configuration is such that input is made to the adder via a second delay circuit.

In the harmonic suppression cooperative control apparatus for an AC / DC converter according to claim 1 of the present invention, the control angle α of the controller for the AC / DC converter is controlled by the first and second level detectors to the upper limit of the limit value or Detects if the lower limit is reached. First, the level detector connected to the harmonic suppression control circuit determines the presence or absence of the output signal of the harmonic suppression control circuit, that is, the presence or absence of the harmonic instability phenomenon.

Then, when the control angle α has reached the upper limit or the lower limit of the limit value and there is an output signal of the harmonic suppression control circuit, either bias setting switch is closed to close any bias setting circuit. Is enabled and is injected into the adder via the first-order delay circuit, so that the control angle α is gradually biased so as to be out of the limiter.

A harmonic suppression cooperative control apparatus for an AC / DC converter according to claim 2 of the present invention is the same harmonic suppression cooperative control apparatus for an AC / DC converter as in claim 1, wherein the output of the harmonic suppression control circuit is Among these, the first and second rectifier circuits that output only the negative or positive input signal by inverting them to the positive or negative polarity, respectively, and the control angle of the AC / DC converter reaches the upper limit or the lower limit of the limit value. Connected to the first and second rectifier circuits via first and second level detectors that determine whether or not the control angle is reached, and corresponding switches that operate when the control angle reaches the upper limit or the lower limit of the limit value. A primary delay circuit,
The first-order lag circuit generates a bias according to the output of the harmonic suppression control circuit and inputs it to the adder.

In the harmonic suppression cooperative control apparatus for an AC / DC converter according to claim 2 of the present invention, the control angle α of the controller for the AC / DC converter is set to the upper limit or the upper limit value by the first and second level detectors. Detects if the lower limit is reached. If it is determined that the upper and lower limits are reached, close either switch. On the other hand, the output of the harmonic suppression control circuit outputs a signal in which only the one-way shake component is detected by the rectifier circuit, and the output fluctuation is slowly operated via the first-order lag circuit and injected into the adder, A bias is gradually applied so that the control angle α deviates from the limiter.

According to a third aspect of the present invention, in the harmonic suppression cooperative control apparatus for an AC / DC converter according to the second aspect, a peak hold circuit is provided instead of the rectifying circuit.

According to a third aspect of the present invention, in the harmonic suppression cooperative control apparatus for an AC / DC converter according to the second aspect, the first and second rectifier circuits are replaced by peak hold circuits, respectively. The effect is the same although the effect is different in that a bias of polarity is generated.

A harmonic suppression cooperative control apparatus for an AC / DC converter according to a fourth aspect of the present invention generates a control pulse from a pulse generator in accordance with a control angle output output through a limiter, and the converter produces a control pulse. A control device for an AC / DC converter that operates the control angle of the control angle output when the control angle output reaches an upper limit value or a lower limit value of the limiter and there is an output signal from a harmonic suppression circuit. Is provided with a means for adding a bias output to the control angle output so as to deviate from the upper limit value or the lower limit value of the limiter.

[0022]

1 is a block diagram showing an embodiment of a harmonic suppression cooperative control apparatus for an AC / DC converter according to the present invention. In FIG. 1, the same parts as those in FIG. In the present embodiment, the level detector 31 is provided at the output of the harmonic suppression control circuit 24, while the control angle α of the control device 10 of the AC / DC converter is input to the level detectors 32 and 33.

The outputs of the level detectors 32 and 33 are input to the logical product circuits 34 and 35 together with the output of the level detector 31, and the bias input switches 36 and 37 are closed by this output to output the bias setting circuits B1 and B2. The outputs are connected so that they are valid. Further, these outputs are configured to be injected from the adder 25 to the controller 10 of the AC / DC converter via the first-order delay circuit 38.

Next, the operation will be described. In FIG. 1, the level detector 31 monitors the output of the harmonic suppression control circuit 24, and when the output exceeds a certain value, the output is set to the logic level "1" as shown in (2) of FIG. To do.

On the other hand, the level detectors 32 and 33 determine whether the control angle α of the control device 10 of the AC / DC converter is stuck to the upper limit or the lower limit of the limit value. , The output of the level detector 32 is set to the logic level "1".

When the control angle α sticks to the upper limit of the limit value and there is an output signal of the harmonic suppression control circuit 24,
The output logic level of the AND circuit 34 also becomes "1". As a result, the bias rush switch 36 is closed, the output of the bias setting circuit B1 becomes effective, and the output is injected into the adder 25 via the first-order delay circuit 38. By doing so, a bias is gradually applied so that the control angle α deviates from the limiter upper limit.

The above is the case where the upper limit is stuck, but when the lower limit is stuck, the level detector 33 and the AND circuit 3
5. The bias rush switch 37 operates to enable the output of the bias setting circuit B2, but the operation is the same as above.

According to the present embodiment, the harmonic instability phenomenon occurs, and the control angle α of the control device 10 of the AC / DC converter is controlled.
The bias is gradually applied to the control angle α only when is attached to the upper limit or the lower limit of the limit value, so the effect of the harmonic suppression control circuit can be maximized, and the AC / DC converter is not used unless necessary. This has an effect of obtaining a coordinated operation that does not affect the operation of the control device 10.

FIG. 3 is a block diagram showing another embodiment. The characteristic part of this embodiment is the harmonic suppression control circuit.
The rectifier circuits 39 and 40 are provided at the output of 24, while the control angle α of the controller 10 of the AC / DC converter is input to the level detectors 32 and 33. The outputs of the level detectors 32 and 33 are connected so that the outputs of the rectifier circuits 39 and 40 are enabled by closing the switches 36 and 37. Further, these outputs are injected from the adder 25 to the controller 10 of the AC / DC converter via the first-order delay circuit 38.

Next, the operation will be described. In FIG. 3, rectifier circuits 39 and 40 rectify the output of the harmonic suppression control circuit 24, and for example, in the rectifier circuit 40, as shown in FIG.

On the other hand, the level detectors 32 and 33 determine whether the control angle α of the control device 10 of the AC / DC converter is stuck to the upper limit or the lower limit of the limit value. , The output of the level detector 32 is set to the logic level "1".

As a result, the switch 37 is closed and the output of the rectifier circuit 40 is input to the primary delay circuit 38. By appropriately selecting the delay time constant and the gain in the first-order delay circuit 38, it is possible to generate an appropriate bias according to the magnitude of the output of the harmonic suppression control circuit 24.

By injecting this into the adder 25, a bias is gradually given so that the control angle α deviates from the limiter upper limit. The above is the case where the upper limit is stuck, but when the lower limit is stuck, the level detector 33, the rectifier circuit 39, and the switch 36 operate, and the same operation as above is performed.

According to this embodiment, the harmonic instability phenomenon occurs and the control angle α of the control device 10 of the AC / DC converter is controlled.
Is applied to the upper limit or the lower limit of the limit value, a bias of an appropriate size is gradually added to the control angle α, so the effect of the harmonic suppression control circuit can be maximized, and when necessary. Has an effect of obtaining a coordinated operation that does not affect the operation of the control device 10 of the AC / DC converter.

FIG. 5 is a block diagram showing still another embodiment. The feature of this embodiment is that the output of the harmonic suppression control circuit 24 is provided with peak hold circuits 41 and 42, while the control angle α of the controller 10 of the AC / DC converter is input to the level detectors 32 and 33. That is the point. Level detector 32, 33
It is connected so that the outputs of the peak hold circuits 41 and 42 become effective by closing the switches 36 and 37 with the output of.
Further, these outputs are added to the first-order delay circuit 38 through the adder.
It is configured to inject from 25 to the control device 10 of the AC / DC converter.

Next, the operation will be described. In FIG. 5, the peak hold circuits 41 and 42 are harmonic suppression control circuits.
The peak value of the output of 24 is held. For example, the peak hold circuit 42 holds the peak value of the positive polarity input signal as shown in FIG.

On the other hand, the level detectors 32 and 33 determine whether the control angle α of the control device 10 of the AC / DC converter sticks to the upper limit or the lower limit of the limit value. , The output of the level detector 32 is set to the logic level "1". As a result, the switch
37 is closed and the output of the peak hold circuit 42 is input to the primary delay circuit 38.

By properly selecting the delay time constant in the first-order delay circuit 38, an appropriate bias can be generated according to the magnitude of the output of the harmonic suppression control circuit 24, and this bias is injected into the adder 25. By doing so, a bias is gradually applied so that the control angle α deviates from the upper limit limit. The above is the case of sticking to the upper limit, but when sticking to the lower limit, level detector 33, peak hold circuit 41, switch
36 operates, and the same operation as above is performed.

According to this embodiment, the harmonic instability phenomenon occurs and the control angle α of the control device 10 of the AC / DC converter is controlled.
Is applied to the upper limit or the lower limit of the limit value, a bias of an appropriate size is gradually added to the control angle α, so the effect of the harmonic suppression control circuit can be maximized, and when necessary. Has an effect of obtaining a coordinated operation that does not affect the operation of the control device 10 of the AC / DC converter.

In each of the above-mentioned embodiments, when the limiter is stuck to the upper limit and the lower limit, two level detectors and two switches are provided.
Although a set is provided, if the power transmission direction of the AC / DC converter is constant, it is decided whether to stick to the upper limit or the lower limit during normal operation depending on the forward converter or the inverse converter. You may provide only a group.

In addition, the position of the adder 25 is provided between the minimum value selection circuit 16 and the limiter 26 in each of the embodiments. For example, in the forward converter, it is the input point of the current control device 13. In the inverse converter, the same effect can be obtained even if it is provided in the minimum margin angle setting portion of the margin angle control device 14.

[0042]

As described above, according to the present invention, when the harmonic instability phenomenon occurs and the control angle of the control device of the AC / DC converter sticks to the upper limit or the lower limit of the limit value. Only because it is configured to apply an appropriate amount of bias to the control angle, the effect of the harmonic suppression control circuit can be maximized, and it does not affect the operation of the control device of the AC / DC converter except when necessary. This has the effect of obtaining a coordinated operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a harmonic suppression cooperative control apparatus for an AC / DC converter according to the present invention.

FIG. 2 is an operation explanatory diagram of FIG.

FIG. 3 is a block diagram showing another embodiment of a harmonic suppression cooperative control apparatus for an AC / DC converter according to the present invention.

FIG. 4 is an operation explanatory diagram of FIG. 3;

FIG. 5 is a block diagram showing still another embodiment of a harmonic suppression cooperative control apparatus for an AC / DC converter according to the present invention.

6 is an explanatory diagram of the operation of FIG.

FIG. 7 is a block diagram of a configuration of a conventional AC / DC converter and a controller.

FIG. 8 is a configuration diagram of a device installed together with the AC / DC converter.

FIG. 9 is a block diagram of a control device of a conventional AC-DC converter and a harmonic suppression control circuit.

[Explanation of symbols]

1,7 AC bus 2,6 Transformer transformer 3,5 converter 4 DC reactor 8 DC voltage detector 9 DC current detector 10 Control device 11 AC voltage detector 12 Voltage control device 13 Current controller 14 Margin control device 15 Phase detector 16 Minimum value selector 17 pulse generator 18 AC filter 19 Phasing capacitor 20 power lines 21 AC system 22 Filter 23 Control circuit 24 Harmonic suppression control circuit 25 adder 26 Limiter 30 Harmonic suppression cooperative control device 31, 32, 33 Level detector 34, 35 AND circuit 36, 37 switch 38 First-order delay circuit 39, 40 rectifier circuit 41, 42 Peak hold circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02J 3 / 24,3 / 36 H02J 1 / 00,1 / 02 H02M 1 / 08,1 / 12

Claims (4)

(57) [Claims] 1. The final control angle output is the smallest of the control angle output from the voltage control device, the control angle output from the current control device and the control angle output from the margin angle control device.
A control device for an AC / DC converter that inputs a control pulse to the adder together with the output from the harmonic suppression control circuit, and operates the control angle of the converter by this pulse output. A first level detector for detecting that the second control unit and a second level detector for determining whether or not the control angle of the control device of the AC / DC converter has reached the upper limit or the lower limit of the limiter.
Alternatively, the output of the third level detector and the output of the first level detector are used as a common input, and the output of the second level detector or the output of the third level detector is used as the other input, and AND conditions are respectively applied. And the first and second bias setting circuits which are respectively connected to the respective AND circuits in advance and each have a closing switch, and each of the bias setting circuits as a primary delay circuit. A harmonic suppression cooperative control apparatus for an AC / DC converter, characterized in that it is configured to be input to the adder via the above. 2. A control angle from a voltage control device and a current control.
Control angle output from the control device and control from the margin angle control device
The smallest of the angle outputs is the final control angle output,
Input to the adder together with the output from the harmonic suppression control circuit
A control pulse is generated and the output of this pulse causes the converter to
A control device for an AC / DC converter that operates a control angle,
Negative or positive input from the output of the harmonic suppression control circuit
Outputs only the signal after inverting it to positive or negative polarity respectively.
The control angles of the first and second rectifier circuits and the AC / DC converter are
Judge whether the upper or lower limit of the mitt value has been reached
The first and second level detectors, and the control angle is limited
A corresponding switch that operates when the upper or lower limit of the value is reached.
Primary delay connected to the first and second rectifier circuits via
Circuit and the first-order lag circuit
Generate a bias according to the output and input this to the adder.
The harmonics of an AC / DC converter characterized in that
Wave suppression cooperative control device. 3. The harmonic suppression cooperative control apparatus for an AC / DC converter according to claim 2, wherein a peak hold circuit is provided instead of the rectifier circuit. 4. A controller for an AC / DC converter, wherein a control pulse is generated from a pulse generator in response to a control angle output outputted via a limiter, and the control angle of the converter is controlled by the control pulse. When the angle output reaches the upper limit value or the lower limit value of the limiter and there is an output signal from the harmonic suppression circuit, the bias output is controlled so that the control angle output deviates from the upper limit value or the lower limit value of the limiter. A harmonic suppression cooperative control device for an AC / DC converter, comprising means for adding to the angular output.