JPH10224994A - Frequency controller for dc transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a system for linking AC systems through DC transmission well both for normal fluctuation and significant disturbance of load. SOLUTION: An emergency/normal switch 14 receives frequency deviations F1 and F2 of systems A and B and makes a decision that an emergency state has occurred when the frequency fluctuation of any one of the AC systems A, B deviates from the range of normal fluctuation of load. Consequently, an emergency switch signal E is turned on to start operation of an integrator 8' in a proportional integration control system 1'. The emergency/normal switch 14 also receives an output from the integrator 8' and turns the emergency switch signal E off when respective frequency fluctuations are within the range of normal fluctuation of load and the output from the integrator 8' is close to 0 thus stopping operation of the integrator 8'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a frequency control device in a DC power transmission system, an asynchronous interconnection system, and a frequency conversion system.

[0002]

2. Description of the Related Art A frequency control device for a DC transmission system uses a AC / DC converter to interconnect two different AC systems by DC transmission, and inputs a frequency deviation detected from a bus voltage of both AC systems. This is a device that suppresses frequency fluctuation of both AC systems by giving a DC power command value interchangeable between both AC systems to converter control.

In order to expect a sufficient frequency fluctuation suppressing effect, it is necessary to provide power corresponding to the capacity of the AC system, and it is necessary to increase the gain of the power for frequency fluctuation. However, in the case of proportional control, the control may become oscillating as the gain is increased, and this is not a problem with normal load fluctuation, but if there is a large disturbance such as a power loss accident, a large frequency There were problems such as the remaining offset. For this reason, in recent years, as the interconnection capacity due to direct current has increased, attempts have been made to adopt a control system configuration having an integral element such as a proportional integral or integral type optimal regulator.

FIG. 7 is a diagram showing a configuration of a frequency control device 2 when a proportional-integral control system 1 is used. This frequency control device 2 includes AC / DC converters 4A, 4A,
B. Frequency detectors 5A and 5B for detecting a system A frequency and a system B frequency from the first AC system A and the second AC system B interconnected via B, respectively, and the system A frequency and the first AC The deviation F2 between the system B frequency and the reference frequency of the second AC system B (hereinafter referred to as system B frequency deviation) F2 is subtracted from the deviation F1 from the reference frequency of system A (hereinafter referred to as system A frequency deviation). Subtractor 6 that outputs the difference between the frequency deviations, a proportional calculator 7 that multiplies the difference between the frequency deviations by a proportional gain, an integrator 8 that integrates the difference between the frequency deviations, and each of the proportional calculator 7 and the integrator 8 An adder 9 for calculating the difference between the power command values by adding outputs; and a power setter 1 for outputting a power set value S which is constantly transmitted regardless of frequency fluctuation.
It comprises an adder 12 that adds 0 to the output of the adder 9 and the power set value S to output a power command value P to the converter control device 11.

The frequency control device 2 calculates the difference between the power command values P by proportionally integrating the difference between the frequency deviations. The difference between the power command value P and the power set value S that is constantly transmitted irrespective of the frequency fluctuation is added to the power command value P, which becomes the control target value of the converter control device 11.

Therefore, when the system A frequency deviation F1 changes in the positive direction and the system B frequency deviation F2 changes in the negative direction, the DC power from the first AC system A to the second AC system B is increased. When the frequency fluctuation direction is opposite, the power command value P is adjusted so as to increase the DC power from the second AC system B to the first AC system A, and the overall AC system Are respectively suppressed.

[0007]

The control system having the above-described integral element has the advantages of being more stable than the proportional control and of eliminating frequency offset at the time of a large disturbance. If the frequency deviation between the AC systems continues for a long time, integration is performed until the frequencies of both AC systems are balanced, so that the interchange power deviates from the power set value preset for system operation. There is.

The present invention has been made in view of such a point, and has a control characteristic that is not restricted by a power set value for a large disturbance and has no frequency offset remaining, and a control characteristic for a normal load change. An object of the present invention is to provide a frequency control device having a control characteristic in which interchange power is maintained near a power set value.

[0009]

In order to achieve the above object, an object of the present invention is to adjust power to be interchanged between two AC systems interconnected by a DC line via an AC / DC converter. In a frequency control device for a DC transmission system that suppresses frequency fluctuations of an AC system, a subtractor that inputs a frequency deviation between a measurement frequency of two AC systems and each of the reference frequencies, and calculates a difference between these frequency deviations, A proportional calculator for performing a proportional calculation of the difference of the frequency deviation from the subtractor,
An integrator that integrates the difference of the frequency deviation from the subtractor when the emergency switching signal is on, and turns on the emergency switching signal when at least one of the frequency deviations becomes larger than a predetermined value; An emergency / normal switching device that turns off the emergency switching signal when the deviations are all equal to or less than a fixed value and the output of the integrator is approximately zero, and power that outputs an arbitrarily set power set value It is characterized by comprising a setter, and an adder for calculating the power to be exchanged between the two AC systems based on the output of the proportional calculator, the output of the integrator, and the output of the power setter.

According to the first aspect of the present invention, the normal state is selected for the frequency change with respect to the normal load change, and the proportional control based on the power set value is performed. When the frequency variation deviates from the normal range, an emergency is selected to activate the integrator, and control is performed by proportional integration, which has characteristics of good stability and eliminating offset.

According to a second aspect of the present invention, there is provided a frequency controller which receives a frequency deviation between a measurement frequency of two AC systems and a reference frequency thereof, and calculates a difference between these frequency deviations, and a subtracter for calculating the difference between these frequency deviations. A proportional calculator for proportionally calculating the difference of the frequency deviation from the integrator, an integrator for integrating the difference of the frequency deviation from the subtractor and outputting an integrated calculation value limited by the upper and lower limiters, and at least one of the frequency deviations An emergency / normal switching device that turns on the emergency switching signal when one of them becomes larger than a predetermined value, and turns off the emergency switching signal when any of the frequency deviations becomes smaller than a certain value; The upper and lower limiters of the integrator are opened to predetermined upper and lower limits when the emergency switching signal from the emergency / normal switching device is on, and the upper and lower limits are set when the emergency switching signal changes from on to off. A limiter controller that closes at a predetermined rate of change, and an adder that calculates power to be exchanged between the two AC systems based on the output of the proportional calculator and the output of the integrator. I do.

According to the second aspect, the normal state is selected for the frequency fluctuation with respect to the normal load fluctuation, and the proportional control based on the power set value is performed. When the frequency variation deviates from the normal range, the limiter of the integrator is opened by selecting an emergency, and the control is performed with the characteristic that the offset is eliminated with good stability by proportional integration. When the frequency fluctuation returns to the normal range, the normal state is selected, and the limiter of the integrator is slowly closed to return to the normal proportional control.

According to a third aspect of the present invention, there is provided a frequency control apparatus which inputs a frequency deviation between a measured frequency of two AC systems and respective reference frequencies, and calculates a control amount by a state feedback gain; At least one of a servo computing unit for proportionally calculating and adding the deviation between the deviation and the corresponding target value, an integrator for integrating the output of the servo computing unit when the emergency switching signal is on, and a frequency deviation Is greater than or equal to a predetermined value, the emergency switching signal is turned on, and when the wave number deviation is less than a certain value and the output of the integrator is almost near zero, the emergency switching signal is turned off. A normal-time switch, a power setter that outputs an arbitrarily set power set value, an output of a state feedback controller, an output of an integrator, and a power setter. Characterized by comprising an adder for calculating the power to be interchange between the two AC systems based on force.

According to a third aspect of the present invention, the normal state is selected for the frequency fluctuation with respect to the normal load fluctuation, and the optimal regulator control is performed only by the state feedback based on the power set value. When the frequency variation deviates from the normal range, the integrator is activated by selecting an emergency, and the control having the characteristic that the offset is eliminated with good stability is performed by the integral type optimal regulator control. .

According to a fourth aspect of the present invention, there is provided a frequency control apparatus for inputting a frequency deviation between a measured frequency of two AC systems and respective reference frequencies and calculating a control amount by a state feedback gain; A servo calculator for proportionally calculating and adding the difference between the deviation and the corresponding target value, and an integrator for integrating the output of the servo calculator and outputting an integrated calculation value limited by the upper and lower limiters, The emergency switching signal is turned on when at least one of the frequency deviations becomes larger than a predetermined value, and the emergency switching signal is turned off when all the frequency deviations become smaller than a predetermined value. When the emergency switch signal from the emergency / normal switch is ON, the upper / lower limiter of the integrator is opened to a predetermined upper / lower limit, and the emergency switch is performed. Limiter controller that closes the upper and lower limiters at a predetermined rate when the signal changes from on to off, and the power to be exchanged between the two AC systems based on the output of the state feedback controller and the output of the integrator And an adder for calculating

According to the present invention, the normal state is selected for the frequency fluctuation with respect to the normal load fluctuation, and the optimal regulator control is performed only by the state feedback based on the power set value. When the frequency fluctuation is out of the normal range, the limiter of the integrator is opened by selecting the emergency, and the control with the characteristic that the stability is good and the offset is eliminated by the integral type optimal regulator control. Done. When the frequency change returns to the normal range, the normal state is selected. By slowly closing the limiter of the integrator, the control returns to the optimal regulator control using only the state feedback in the normal state.

According to a fifth aspect of the present invention, there is provided a frequency controller which receives a frequency deviation between a measured frequency of two AC systems and a reference frequency, and calculates a difference between these frequency deviations, and a subtracter for calculating the difference between these frequency deviations. A proportional calculator that calculates the difference of the frequency deviation from the input value, a state feedback controller that inputs the frequency deviation and calculates the control amount by the state feedback gain, and a proportional calculation that calculates the difference between the frequency deviation and the corresponding target value. And an adder for calculating the output of the integration type optimal regulator based on the output of the state feedback controller and the output of the integrator; and a frequency deviation. When at least one of them becomes larger than a predetermined value, the emergency switching signal is turned on, and any frequency deviation is below a certain value. An emergency / normal switching device that turns off the emergency switching signal when the integral type optimal regulator output becomes almost zero, a power setting device that outputs an arbitrarily set power set value, and an emergency / When the emergency switching signal from the normal switching unit is on, select the integral type optimal regulator output. When the emergency switching signal is off, select the output of the proportional arithmetic unit. A switching calculator for calculating the power to be exchanged between the two AC systems based on the set value.

According to the present invention, the normal state is selected for the frequency fluctuation with respect to the normal load fluctuation, and the proportional control based on the power set value is performed. If the frequency variation deviates from the normal range, an emergency is selected, so that the control is switched from the proportional control to the integral type optimal regulator control, and the control is performed with the characteristics that the stability is good and the offset is eliminated. .

According to a sixth aspect of the present invention, there is provided a frequency controller for inputting a frequency deviation between a measured frequency of two AC systems and respective reference frequencies, and calculating a difference between the frequency deviations, and a subtracter. A proportional calculator for proportionally calculating the difference of the frequency deviation from, a state feedback controller for inputting the frequency deviation and calculating the control amount by the state feedback gain, and performing a proportional calculation for the deviation between the frequency deviation and the corresponding target value, respectively. A servo calculator for addition, and an integrator for integrating the output of the servo calculator and outputting an integration calculation value limited by the upper and lower limiters, and controlling based on the output of the state feedback controller and the output of the integrator Emergency shutoff when at least one of the integral type optimal regulator that outputs the amount and the frequency deviation exceeds a predetermined value. An emergency / normal switching device that turns on the signal and turns off the emergency switching signal when any of the frequency deviations is below a certain value, and an emergency switching signal from the emergency / normal switching device is on. A limiter controller that opens the upper and lower limiters of the integral type optimal regulator to predetermined upper and lower limits when the emergency switching signal changes from on to off, and closes the upper and lower limiters at a predetermined rate of change. When the emergency switching signal from the normal switching device is on, the output from the integral type optimal regulator is selected. When the emergency switching signal changes from on to off, the output of the proportional arithmetic unit is selected after a predetermined time has elapsed. A delay switching calculator for calculating the power to be exchanged between the two AC systems.

According to the present invention, the normal state is selected for the frequency fluctuation with respect to the normal load fluctuation, and the proportional control based on the power set value is performed. When the frequency variation deviates from the normal range, an emergency is selected, so that the control is switched from the proportional control to the integral type optimal regulator control, and the control is performed with the characteristics that the stability is good and the offset is eliminated. When the fluctuation of the frequency returns to the normal range, the normal state is selected. After the limiter of the integral type optimal regulator is slowly closed, the control returns to the normal proportional control.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same reference numerals are given to portions common to the conventional example, and redundant description will be omitted.

FIG. 1 is a diagram showing a first embodiment of the frequency control device of the present invention. In this embodiment, FIG.
An emergency / normal switch 14 for generating an emergency switch signal E for operating and stopping the integrator 8 'is added to the conventional configuration shown in FIG.

The emergency / normal switching unit 14 receives the system A frequency deviation F1 and the system B frequency deviation F2, and deviates from the range due to normal load fluctuations regardless of the frequency fluctuation range of the AC systems A and B. If an emergency decision is made,
The emergency switching signal E output to the integrator 8 'is turned on. The emergency / normal switching unit 14 also receives the output of the integrator 8 ', and the respective frequency fluctuation ranges are within the range due to normal load fluctuation, and the output of the integrator 8' is near zero. Sometimes, the emergency switching signal E is reset to off.

In the proportional integral control system 1 ', the subtracter 6 subtracts the system B frequency deviation F2 from the system A frequency deviation F1. The proportional calculator 7 multiplies the output of the subtractor 6 by a proportional gain. The integrator 8 'integrates and outputs the output of the subtractor 6 only when the emergency switching signal E is output on. The adder 9 adds the output of the proportional calculator 7 and the output of the integrator 8 ',
Outputs a proportional-integral control signal.

A power set value S is set in the power setter 10 by an operator, and an adder 12 adds the output of the proportional-integral control system 1 to the power set value S from the power setter 10 and sets a power command value P Is output.

In the frequency control device configured as described above, when the fluctuation range of the frequency of the AC systems A and B is within the range due to the normal load fluctuation, the output of the integrator 8 'becomes 0 and the proportional operation is performed. The control is performed only by the output of the heater 7, and the control is performed without deviation from the power set value S.

If the frequency fluctuation range of either of the AC systems A and B deviates from the range due to normal load fluctuation due to a system fault, the emergency / normal switch 14 outputs the emergency switching signal E on. As a result, the integrator 8 'operates,
Control is performed by the proportional integral control so as to be stable and eliminate the frequency offset.

After the frequency fluctuation due to the system failure is suppressed, the operator slowly changes the power set value S of the power setting device 10 so as to match the power command value P. As a result, the output of the integrator 8 'becomes close to 0, the emergency / normal switching unit 14 resets the emergency switching signal E, and returns to the normal proportional control by the proportional calculator 7 alone.

As is apparent from the above description, according to the present embodiment, when the frequency fluctuation range is within the range due to the normal load fluctuation, the power interchange based on the power set value is performed by the proportional control. Done. On the other hand, in the event of a system failure, the power transfer is not restricted by the power set value by the proportional integral control, and the large frequency fluctuation caused by the accident is suppressed stably and the system is shifted to a new steady state where the frequency offset has been eliminated. Can be.

FIG. 2 is a diagram showing a second embodiment of the frequency control device of the present invention. In this embodiment, FIG.
The integrator 8 'is replaced with an integrator 8 "having upper and lower limiters as compared with the first embodiment shown in FIG.
A limiter controller 16 for controlling the upper and lower limiters is added. Further, the emergency / normal switching unit 14 'makes an emergency / normal determination using only the system A frequency deviation F1 and the system B frequency deviation F2, and outputs an emergency switching signal E.
Is supplied to the limiter controller 16 instead of the integrator 8 ″.

That is, the emergency / normal switch 14 '
Inputs the system A frequency deviation F1 and the system B frequency deviation F2, and when any of the fluctuations of the frequency is out of the range due to the normal load fluctuation, makes an emergency judgment. The emergency switching signal E is turned on.
When both the frequency fluctuation ranges are within the range due to the normal load fluctuation, the emergency switching signal E is reset to off.

The limiter controller 16 includes a change rate limiter 18H for the upper limit and a change rate limiter 18L for the lower limit, and a switch 20H arranged on the input side of the change rate limiter 18H for selecting whether the maximum power is 0 or not. And a switch 20L arranged on the input side of the rate-of-change limiter 18L to select the minimum power or 0, and to select between the maximum power or the output of the rate-of-change limiter 18H arranged on the output side of the rate-of-change limiter 18H. And a switch 22L disposed on the output side of the rate-of-change limiter 18L to select between the minimum power and the output of the rate-of-change limiter 18L.

The switch 20H selects 0 when the emergency switching signal E is off, and selects the maximum power when the emergency switching signal E is on. The change rate limiter 18H is a switch 2
When an output of 0H is input and the input value changes from the maximum power to 0, the change rate is limited and a value that decreases from the maximum power to 0 at a predetermined change rate is output. Switch 22H
Is the rate-of-change limiter 18 when the emergency switching signal E is off.
The output of H is selected, and when the emergency switching signal E is on, the maximum power is selected and set as the upper limit of the limiter of the integrator 8 ″.

The switch 20L selects 0 when the emergency switching signal E is off, and selects the minimum power when the emergency switching signal E is on. The change rate limiter 18L is
When an output of 0 L is input and the input value changes from the minimum power to 0, the change rate is limited and a value that increases from the minimum power to 0 at a predetermined change rate is output. Switch 22L
Is the rate-of-change limiter 18 when the emergency switching signal E is off.
The output of L is selected, and when the emergency switching signal E is on, the minimum power is selected and set as the lower limit of the limiter of the integrator 8 ″.

In the proportional integral control system 1 ", the subtractor 6 subtracts the system B frequency deviation F2 from the system A frequency deviation F1.
The proportional calculator 7 multiplies the output of the subtractor 6 by a proportional gain.
The integrator 8 "integrates the output of the subtractor 6 within the range of the upper and lower limits set by the limiter controller 16. The output of the integrator 8" is added to the output of the proportional calculator 7 by the adder 9. The output is the output of the proportional-integral control system 1 ″.
Adds the output of the proportional-integral control system 1 ″ to the power set value S set in the power setter 10, and outputs a power command value P.

In the frequency control device configured as described above, when the frequency fluctuation range of the AC systems A and B is within the range due to the normal load fluctuation, the output of the integrator 8 ″ becomes 0 and the proportional operation is performed. The control is performed only by the output of the heater 7, and the control is performed without deviation from the power set value S.

If the frequency fluctuation range of either of the AC systems A and B deviates from the range due to the normal load fluctuation due to a system accident, the emergency / normal switch 14 'outputs the emergency switching signal E on. The upper and lower limiters of the integrator 8 ″ are opened to the maximum value and the minimum value by the limiter controller 16. Therefore, control is performed by the proportional integral control so as to be stable and eliminate the frequency offset without suppressing the integral control amount. Is performed.

When the frequency fluctuation due to the system fault is controlled, the emergency switching signal E is reset by the emergency / normal switching unit 14 ', and the change rate limiter 18 of the limiter controller 16 is reset.
The input of H is switched from the maximum power to 0 by the switch 20H, and the input of the rate-of-change limiter 18L is switched from the minimum power to 0 by the switch 20L. At the same time, the switch 22H switches from the maximum power to select the output of the rate-of-change limiter 18H, and the switch 22L switches from the minimum power to select the output of the rate-of-change limiter 18L. This causes the upper and lower limiters of the integrator 8 ″ to close slowly.

Therefore, according to the present embodiment, when the frequency fluctuation width of the AC systems A and B is within the range due to the normal load fluctuation, the power interchange based on the power set value is performed by the proportional control. In the event of a system failure, power integration is performed without being restricted by the power set value by proportional integral control, and it is possible to stably suppress large frequency fluctuations caused by the accident and shift the system to a new steady state in which the frequency offset has been eliminated. it can.

FIG. 3 is a diagram showing a third embodiment of the frequency control device of the present invention. In this embodiment, FIG.
Is compared with the first embodiment shown in FIG.
Instead, an integral type optimal regulator 24 is used. The integration type optimal regulator 24 includes a state feedback controller 26 that inputs the system A frequency deviation F1 and the system B frequency deviation F2 as state variables, and a system A frequency deviation F1.
1 and system B frequency deviation F2 from the respective target values, subtracters 28A and 28B, and subtracters 28A and 28
A servo computing unit 30 to which the output of B is inputted, an integrator 32 to which the output of the servo computing unit 30 is inputted and which operates / disables by the emergency switching signal E, and outputs of the state feedback controller 26 and the integrator 32 And a subtractor 34 for inputting. The emergency / normal switching unit 14 receives the system A frequency deviation F1 and the system B frequency deviation F2, and inputs the output of the integrator 32 of the integrating type optimal regulator 24 as a determination signal. Emergency / normal switching device 1
4 determines the emergency when the fluctuation range of the frequency of any of the AC systems is out of the range due to the normal load fluctuation, and turns on the emergency switching signal E to the integrator 32.
Then, the emergency switching signal E is reset when the respective frequency fluctuation ranges are both ranges due to normal load fluctuation and the output of the integrator 32 is near zero.

In the integral type optimal regulator 24, the state feedback controller 26 applies a gain to each of the system A frequency deviation F1 and the system B frequency deviation F2 (and the output of the state estimator if a state estimator is provided). to add. The subtracters 28A and 28B are provided with a system A frequency deviation F1, a system B
The frequency deviation F2 is subtracted from each target value (usually 0). The servo calculator 30 multiplies the output of each of the subtracters 28A and 28B by a gain and adds them. Integrator 32
Is an emergency switching signal E from the emergency / normal switching unit 14
Only when is ON, the output of the servo calculator 30 is integrated and output. The subtractor 34 is connected to the state feedback controller 26.
Is added to the output of the integrator 32 to obtain an integral type optimal regulator output.

The adder 12 adds the integral type optimal regulator output from the subtractor 34 to the power set value S set in the power setter 10, and outputs a power command value P.

In the frequency control device configured as described above, when the fluctuation range of the frequency of the AC systems A and B is within the range due to normal load fluctuation, the emergency / normal switching device 1 is used.
Since the emergency switching signal E from 4 is off, the output of the integrator 32 becomes 0, the control is performed only by the state feedback controller 26, and the control is performed without deviation from the power set value S.

If the frequency fluctuation range of either of the AC systems A and B deviates from the range due to the normal load fluctuation due to a system accident, the emergency switching signal E from the emergency / normal switch 14 is turned on. As a result, the integrator 32 operates,
Control is performed so as to be stable and eliminate the frequency offset by the integral type optimal regulator control.

After the frequency fluctuation due to the system accident is suppressed, the operator slowly changes the power set value S of the power setting device 10 so as to match the power command value P. As a result, the output of the integrator 32 becomes near 0, the emergency switching signal E is reset by the emergency / normal switching device 14, and the control returns to the normal control by the state feedback controller 26 alone.

As is clear from the above description, according to the present embodiment, when the frequency fluctuation range is within the range due to the normal load fluctuation, the control of the state feedback alone is performed to control the power set value as the base. Power exchange is performed.
On the other hand, in the event of a system failure, power interchange that is not restricted by the power set value is performed by the integral-type optimal regulator control, stabilizing large frequency fluctuations caused by the accident, and shifting the system to a new steady state in which the frequency offset has been eliminated. Can be done.

FIG. 4 is a diagram showing a fourth embodiment of the frequency control device according to the present invention. In this embodiment, FIG.
As compared with the third embodiment shown in FIG. 7, an integrator 32 'with upper and lower limiters is used instead of the integrator 32, and a limiter controller 16 for controlling the upper and lower limiters of the integrator 32' is added. Have been. The structure of the limiter controller 16 and the operation of the emergency / normal switch 14 'are the same as those described in the second embodiment shown in FIG. Emergency / normal judgment is performed only by the frequency deviation F1 and the system B frequency deviation F2.
An emergency switching signal E is output to the limiter controller 16.

That is, the emergency / normal switch 14 '
Inputs the system A frequency deviation F1 and the system B frequency deviation F2, and when any of the fluctuations of the frequency is out of the range due to the normal load fluctuation, makes an emergency judgment. The emergency switching signal E is turned on.
When both the frequency fluctuation ranges are within the range due to the normal load fluctuation, the emergency switching signal E is reset to off.

The limiter controller 16 outputs an emergency switching signal E
Is on, the maximum power and the minimum power are selected by the switches 22H and 22L, respectively. Therefore, the maximum power and the minimum power are set as the upper limit value and the lower limit value of the limiter of the integrator 32 ', respectively. When the emergency switch signal E changes from ON to OFF, the limiter controller 16 switches the switch 22H.
, 22L select the output of the rate-of-change limiters 18H, 18L. The inputs of the rate-of-change limiters 18H, 18L are switched from the maximum power and the minimum power to 0 by the switches 20H, 20L, respectively. , 18L output values gradually changing from the maximum power to 0 and from the minimum power to 0 as the upper and lower limit set values of the limiter of the integrator 32 '.

In the integration type optimal regulator 24 ', when the state feedback controller 26 has the system A frequency deviation F1, the system B frequency deviation F2, and the state estimator, the output of the state estimator is multiplied by a gain and added. Then, the servo calculator 30 multiplies the respective outputs of the subtractors 28A and 28B by a gain and adds them, and the integrator 32 'sets the output of the servo calculator 30 within the range of the upper and lower limiter widths set by the limiter controller 16. Integrate the output. The output of the state feedback controller 26 and the output of the integrator 32 'are subtracted by a subtractor 34.
And the output of the integral type optimal regulator 24 'is obtained.

The output of the integral type optimal regulator 24 'is
Power set value S set in power setter 10 and adder 12
And output as the power command value Ρ.

In the frequency control device configured as described above, when the frequency fluctuation range of the AC systems A and B is within the range due to normal load fluctuation, the output of the integrator 32 'becomes 0.
The control is performed only by the state feedback controller 26, and the control is performed without deviating from the power set value S.

When the frequency fluctuation range of either of the AC systems A and B deviates from the range due to the normal load fluctuation due to a system fault, the emergency / normal switching device 14 'outputs the emergency switching signal E. When the upper and lower limiters of the integrator 32 'are opened to the maximum value and the minimum value, control is performed by normal integral type optimal regulator control so as to be stable and eliminate the frequency offset.

When the frequency fluctuation due to the system fault is suppressed, the emergency / normal switching unit 14 'resets the emergency switching signal E, and the limiter controller 16 sets the upper limit set by the integrator 32' to the upper and lower limiters. By gradually changing the value and the lower limit to 0, respectively, the upper and lower limiters of the integrator 32 'close slowly.

Therefore, according to the present embodiment, when the frequency fluctuation width of AC systems A and B is within the range due to normal load fluctuation, the power based on the power set value is controlled only by state feedback. Flexibility is provided. On the other hand, in the event of a system failure, power interchange that is not restricted by the power set value is performed by the integral-type optimal regulator control, stabilizing large frequency fluctuations caused by the accident, and shifting the system to a new steady state in which the frequency offset has been eliminated. Can be done.

FIG. 5 is a diagram showing a fifth embodiment of the frequency control device of the present invention. In this embodiment, FIG.
As compared with the third embodiment shown in FIG.
Integrator 3 normally operating instead of integrating optimal regulator 24 having integrator 32 operating / non-operating by
Integral type optimal regulator 24 "provided with 2" is disposed. Proportional control system 36 and the output of proportional control system 36 in response to an emergency switching signal E from emergency / normal switching unit 14 determine whether the output of proportional control system 36 is integral type optimal regulator 24. A switch 38 for selecting one of the 24 ″ outputs is added.

The emergency / normal switching unit 14 receives the system A frequency deviation F1 and the system B frequency deviation F2, and inputs the output of the integral type optimal regulator 24 ″ as a judgment signal. The time switch 14 determines an emergency when the fluctuation width of the frequency of any of the AC systems is out of the range due to the normal load change, turns on the emergency switch signal E, and causes the switch 38 to Then, the emergency switching signal E is reset to OFF when the respective frequency fluctuation ranges are in the range due to the normal load fluctuation and the output of the integral type optimum regulator 24 ″ is near 0.

In the integral type optimum regulator 24 ″, the state feedback controller 26 controls the system A frequency deviation F 1.
, And the system B frequency deviation F2 (and the output of the state estimator if a state estimator is provided), multiplied by a gain, and added to calculate a state feedback control signal. In addition, the servo calculator 30 adds gains to the respective deviations of the system A frequency deviation F1 and the system B frequency deviation F2 from target values, and adds the gain. The integrator 32 ″ integrates the output of the servo operation unit 30. The output of the integrator 32 "and the output of the state feedback controller 26 are input to the subtractor 34, and the output of the integral type optimal regulator 24" is calculated.

The proportional control system 36 has a system A frequency deviation F1.
And a subtractor 6 for calculating the difference between the system B frequency deviation F2 and
The difference is multiplied by a proportional gain to calculate a proportional control signal.

The switch 38 selects the output of the proportional control system 36 when the emergency switching signal E is off, and selects the output of the integral type optimal regulator 24 ″ when the emergency switching signal E is on. , Power set value S set in power setter 10
And outputs the result to the adder 12 in order to obtain the power command value P.

In the frequency control device configured as described above, when the fluctuation range of the frequency of the AC systems A and B is within the range due to the normal load fluctuation, the switch 38 selects the proportional control signal. The control is performed without deviation from the power set value S.

When the frequency fluctuation range of either of the AC systems A and B deviates from the range due to the normal load fluctuation due to a system fault, the output of the integral type optimum regulator 24 ″ is selected, and the output is stable and the frequency offset is eliminated. The control is performed as follows.

After the frequency fluctuation due to the system fault is suppressed, the operator slowly changes the power set value S of the power setting device 10 so as to match the power command value P. As a result, the output of the integral type optimum regulator 24 ″ becomes close to 0, the emergency / normal switching device 14 resets the emergency switching signal E to OFF, and the switching device 38 selects the output of the proportional control system 36 again. Return to normal proportional control.

As is clear from the above description, according to the present embodiment, when the frequency fluctuation range is within the range due to the normal load fluctuation, the power interchange based on the power set value is performed by the proportional control. Is performed. On the other hand, in the event of a system failure, power interchange that is not restricted by the power set value is performed by the integral-type optimal regulator control, stabilizing large frequency fluctuations caused by the accident, and shifting the system to a new steady state in which the frequency offset has been eliminated. Can be done.

FIG. 6 is a diagram showing a sixth embodiment of the frequency control device of the present invention. In this embodiment, FIG.
As compared with the fifth embodiment, the emergency / normal switch 14 is switched to the emergency / normal switch 14 'used in the second and fourth embodiments. , The integral type optimal regulator 24 ″ is replaced by the integral type optimal regulator 24 ′ with an upper / lower limiter used in the fourth embodiment. Further, a limiter controller 16 for controlling the upper / lower limiter and an emergency Time / normal switching device 1
An off-delay timer 40 for transmitting a signal to the switch 38 with a certain delay when the emergency switching signal E from 4 'changes from on to off is added. Limiter controller 16
Has a configuration similar to that shown in the second and fourth embodiments.

The emergency / normal switching unit 14 'makes an emergency / normal determination only with the system A frequency deviation F1 and the system B frequency deviation F2, and the fluctuation width of either frequency is caused by normal load fluctuation. If it is out of the range, the emergency switching signal E transmitted to the limiter controller 16 and the off-delay timer 40 is turned on. When both the frequency fluctuation ranges are within the range due to the normal load fluctuation, the emergency switching signal E is reset to off.

The limiter controller 16 and the integral type optimum regulator 24 'operate as described in the fourth embodiment shown in FIG. The proportional control system 36 operates similarly to the fifth embodiment.

The switch 38 selects the output of the integral type optimal regulator 24 'when the emergency switching signal E is on,
When the emergency switching signal E is off, the off-delay timer 4
By the operation of 0, the output of the proportional control system 36 is selected after a certain time has elapsed.

Adder 12 adds the output of switch 38 to power set value S set in power setter 10, and outputs power command value P.

In the frequency control device configured as described above, the output of the proportional control system 36 is switched by the switch 38 when the fluctuation range of the frequency of the AC systems A and B is within the range due to the normal load fluctuation. The proportional control is performed without deviation from the selected power set value S.

If the frequency fluctuation range of either of the AC systems A and B deviates from the range due to normal load fluctuation due to a system fault, the output of the integral type optimal regulator 24 'is selected, and the upper and lower limiters are set at this time. By opening the maximum value and the minimum value by the limiter controller 16, control is performed so as to be stable and eliminate the frequency offset.

When the frequency fluctuation due to the system fault is suppressed, the emergency switching signal E is reset to off by the emergency / normal switching unit 14 ', the output of the limiter controller 16 is reduced from the maximum power to 0, and the minimum power is reduced. , The upper and lower limiters of the integral type optimal regulator 24 'are slowly closed. After that, the switch 38 is switched by the off-delay timer 40 so that the integral type optimal regulator 2
The output of 4 'is switched to the output of the proportional control system 36 for selection.

Therefore, according to the present embodiment, when the frequency fluctuation width of AC systems A and B is within the range due to normal load fluctuation, power interchange based on the power set value is performed by proportional control. Will be On the other hand, in the event of a system failure, power interchange that is not restricted by the power set value is performed by the integral-type optimal regulator control, stabilizing large frequency fluctuations caused by the accident, and shifting the system to a new steady state in which the frequency offset has been eliminated. Can be done.

[0074]

As described above, according to the present invention, a control characteristic that is stable against large disturbance and has no frequency offset remains;
With respect to normal load fluctuation, it is possible to realize frequency control that also has control characteristics in which the interchange power is maintained near the power set value.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a first embodiment of a frequency control device according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of the frequency control device of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the frequency control device of the present invention.

FIG. 4 is a block diagram illustrating a frequency control device according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram illustrating a frequency control device according to a fifth embodiment of the present invention.

FIG. 6 is a block diagram illustrating a frequency control device according to a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a conventional configuration of a frequency control device.

[Explanation of symbols]

 1, 1 ', 1 "... proportional integral control system 6, 28A, 28B, 34 ... subtractor 7 ... proportional arithmetic unit 8, 8', 8", 32, 32 ', 32 "... ... Integrators 9, 12 ... Adders 10 ... Power setting units 14, 14 '... Emergency / normal switching units 16 ... Limiter controllers 18H, 18L ... Rate-of-change limiters 20H , 20L, 22H, 22L, 38 Switchover 24, 24 ', 24 "... Integral type optimal regulator 26 ... State feedback controller 30 ... Servo calculator 36 ... Proportional control system 40 ……… Off-delay timer

Claims (6)

[Claims] 1. A frequency control device for a DC power transmission system, which controls power to be interchanged between two AC systems interconnected by a DC line via an AC / DC converter to suppress frequency fluctuations of the AC system. A subtractor for inputting the frequency deviation between the measurement frequencies of the two AC systems and the respective reference frequencies, and calculating the difference between these frequency deviations, and a proportional calculator for performing a proportional calculation on the difference between the frequency deviations from the subtractor And an integrator that integrates the difference between the frequency deviation from the subtractor when the emergency switching signal is on, and the emergency switching signal when at least one of the frequency deviations becomes larger than a predetermined value. Is turned on, and the emergency switching signal is turned off when all of the wave number deviations become equal to or less than a predetermined value and the output of the integrator becomes almost zero. And a power setter that outputs a power set value that is arbitrarily set; and an interchange between the two AC systems based on the output of the proportional calculator, the output of the integrator, and the output of the power setter. A frequency control device for a DC transmission system, comprising: an adder for calculating power. 2. A frequency control apparatus for a DC power transmission system, which controls power to be interchanged between two AC systems interconnected by a DC line via an AC / DC converter to suppress a frequency fluctuation of the AC system. A subtractor for inputting the frequency deviation between the measurement frequencies of the two AC systems and the respective reference frequencies, and calculating the difference between these frequency deviations, and a proportional calculator for performing a proportional calculation on the difference between the frequency deviations from the subtractor And an integrator that integrates a difference between the frequency deviations from the subtractor and outputs an integration operation value limited by upper and lower limiters; and at least one of the frequency deviations is larger than a predetermined value. An emergency / normal switching device that turns on the emergency switching signal and turns off the emergency switching signal when all of the frequency deviations become equal to or less than a certain value; The upper and lower limiters of the integrator are opened to predetermined upper and lower limit values when the emergency switching signal from the normal time switch is on, and the upper and lower limiters are set to predetermined values when the emergency switching signal changes from on to off. A limiter controller that performs a closing operation at a change rate, and an adder that calculates power to be exchanged between the two AC systems based on an output of the proportional calculator and an output of the integrator. DC transmission system frequency control device. 3. A frequency control device for a DC power transmission system, which controls power to be interchanged between two AC systems interconnected by a DC line via an AC / DC converter to suppress a frequency fluctuation of the AC system. A state feedback controller for inputting a frequency deviation between the measurement frequencies of the two AC systems and the respective reference frequencies and calculating a control amount by a state feedback gain; and a deviation between the frequency deviation and a corresponding target value, respectively. A servo calculator for calculating and adding, an integrator for integrating the output of the servo calculator when the emergency switching signal is on, and the integrator when at least one of the frequency deviations is larger than a predetermined value. The emergency switching signal is turned on, and when the wave number deviations are all equal to or less than a fixed value and the output of the integrator is substantially near zero, the emergency An emergency / normal switching device for turning off a switching signal; a power setting device for outputting an arbitrarily set power setting value; an output of the state feedback controller, an output of the integrator, and a power setting device. An adder for calculating electric power to be exchanged between the two AC systems based on an output. 4. A frequency control device for a DC power transmission system, which controls power to be interchanged between two AC systems interconnected by a DC line via an AC / DC converter and suppresses frequency fluctuation of the AC system. A state feedback controller for inputting a frequency deviation between the measurement frequencies of the two AC systems and the respective reference frequencies and calculating a control amount by a state feedback gain; and a deviation between the frequency deviation and a corresponding target value, respectively. A servo calculator for calculating and adding; an integrator for integrating the output of the servo calculator to output an integrated calculation value limited by upper and lower limiters; and at least one of the frequency deviation is a predetermined value. When it becomes larger than the above, the emergency switching signal is turned on, and when the frequency deviation becomes less than a certain value, the emergency switching signal is turned on. An emergency / normal switching device to be turned off, and when the emergency switching signal from the emergency / normal switching device is on, the upper / lower limiter of the integrator is opened to a predetermined upper / lower limit, and the emergency switching is performed. A limiter controller that closes the upper and lower limiters at a predetermined rate of change when the signal changes from on to off, and between the two AC systems based on the output of the state feedback controller and the output of the integrator. A frequency control device for a DC power transmission system, comprising: an adder for calculating power to be interchanged. 5. A frequency control apparatus for a DC power transmission system, which controls power to be interchanged between two AC systems interconnected by a DC line via an AC / DC converter to suppress a frequency fluctuation of the AC system. A subtractor for inputting the frequency deviation between the measurement frequencies of the two AC systems and the respective reference frequencies, and calculating the difference between these frequency deviations, and a proportional calculator for performing a proportional calculation on the difference between the frequency deviations from the subtractor A state feedback controller that inputs the frequency deviation and calculates a control amount by a state feedback gain; a servo calculator that calculates and adds a deviation between the frequency deviation and a corresponding target value in proportion to each other; An integrator for integrating the output of the arithmetic unit, and an output of an integrating type optimal regulator based on the output of the state feedback controller and the output of the integrator. An adder for calculating a force, when at least one of the frequency deviations is greater than or equal to a predetermined value, turns on an emergency switching signal, all of the frequency deviations are less than or equal to a predetermined value, and the integral type optimal regulator An emergency / normal switching device for turning off the emergency switching signal when the output becomes almost zero; a power setting device for outputting an arbitrarily set power set value; When the emergency switching signal from the switch is on, the integral type optimal regulator output is selected. When the emergency switching signal is off, the output of the proportional operation unit is selected, and the power from the power setting device is selected. A switching calculator for calculating electric power to be exchanged between the two AC systems based on a set value, the frequency control device for a DC transmission system. 6. A frequency control device for a DC power transmission system, which controls power to be interchanged between two AC systems interconnected by a DC line via an AC / DC converter to suppress a frequency fluctuation of the AC system. A subtractor for inputting the frequency deviation between the measured frequencies of the two AC systems and the respective reference frequencies, and calculating the difference between these frequency deviations, and a proportional calculator for calculating the difference between the frequency deviations from the subtractor in proportion A state feedback controller for inputting the frequency deviation and calculating a control amount by a state feedback gain, a servo calculator for proportionally calculating and adding a deviation between the frequency deviation and a corresponding target value, and the servo calculator An integrator that performs an integral operation on the output of the above and outputs an integral operation value limited by the upper and lower limiters, and an output of the state feedback controller. An integration-type optimal regulator that outputs a control amount based on the output of the integrator, and when at least one of the frequency deviations becomes larger than a predetermined value, turns on the emergency switching signal, and the frequency deviation is An emergency / normal switching device for turning off the emergency switching signal when the emergency switching signal also becomes equal to or less than a predetermined value; and an emergency switching signal from the emergency / normal switching device when the emergency switching signal is on. A limiter controller that opens an upper / lower limiter to a predetermined upper / lower limit value and closes the upper / lower limiter at a predetermined rate when the emergency switching signal changes from on to off; When the emergency switching signal from the switch is on, the output from the integrating type optimal regulator is selected, and when the emergency switching signal changes from on to off, a predetermined time has elapsed. Selects the output of the proportional calculator, the frequency control device of a DC power transmission system, characterized by comprising a delay switch calculator for calculating the power to be interchange between the two AC systems.