JPH0481901A - Automatic controller - Google Patents

Abstract

PURPOSE:To improve the reliability by selecting and outputting an output whose absolute value is larger of outputs of plural sets of detecting parts for detecting a device to be controlled of a control object apparatus, and outputting a manipulated variable to the control object apparatus, based on its output signal. CONSTITUTION:An absolute value height selecting part 12 selects a signal whose absolute value is larger of a signal Va and a signal Vb and outputs a signal V, and in the same way, a signal I, a signal P, and a signal Q are outputted from a signal Ia and a signal Ib, a signal Pa and a signal Pb, and a signal Qa and a signal Qb, respectively by selecting the signal whose absolute value is larger, respectively. An adjusting part 10 executes the excitation control of a synchronizing machine 1, based on an output signal of the absolute value height selecting part 12, executes the control so that a terminal voltage coincides with a target value, and also, adjusts automatically a phase of an ignition pulse PL outputted to a thyristor rectifying device 4 in order to execute a restriction of an output excess current and an insufficient excitation restriction, a drift compensation, and a secondary side control. In such a way, the automatic controller having high reliability can be obtained.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention relates to an automatic control device that automatically controls various process quantities to target values, and in particular takes reliability into consideration. .

(Prior Art) Generally, an automatic control device includes a detection unit for detecting a controlled variable of a controlled device, and an adjustment unit that outputs a manipulated variable to the controlled device so that its output signal matches a target value. However, the importance, public nature, and
When high reliability is required from the viewpoint of safety, reliability is improved by configuring part or all of the automatic control device to be multiplexed.

As a conventional example of such an automatic control device, a conventional example of an excitation control device for a synchronous generator will be described below.

The excitation control device basically automatically controls the terminal voltage of the synchronous generator so that it matches the target value, but it also has the following functions:
It also has functions such as limiting output overcurrent and underexcitation limiting which limits reactive power on the phase advancing side. In addition, in order to perform stable parallel operation of synchronous generators, galvanic compensation that provides terminal voltage droop characteristics with respect to reactive power, and secondary control functions that control reactive power or power factor at a constant level may be provided. be.

FIG. 3 shows a configuration diagram of a conventional dual excitation control device.

A field current is supplied from a thyristor rectifier 4 to a field winding 2 of a synchronous generator l via a field breaker 3.

The AC power source for the thyristor rectifier M4 is supplied by stepping down the terminal voltage of the synchronous generator 1 using the excitation transformer 5.

The detection unit 6a is a potential transformer (hereinafter abbreviated as PT) 7a
secondary voltage and meter alternator (hereinafter abbreviated as CT) 8a
The secondary current of is input, and from these values, a signal Va proportional to the terminal voltage of the synchronous generator l, a signal Ia proportional to the output current, a signal Pa proportional to the active power, and a signal Qa proportional to the reactive power are generated. Output.

The detection section 6b is the same as the detection section 6a, and the PT7b
The secondary voltage of CT8b and the secondary current of CT8b are input, and the signal vb
, a signal Ib, a signal pb, and a signal Qb.

The voltage balancing relay 9 inputs the secondary voltage of PT7a and PT7b, and when the secondary voltage of PT7 is relatively low, an alarm S is issued.
a, and conversely, when the secondary voltage of PT7b is low, an alarm sb is output.

The adjustment unit 10a controls the excitation of the synchronous generator l based on the output signal of the detection unit 6a, and controls the terminal voltage mentioned above so that it matches the target value, and also limits the output overcurrent. The phase of the firing pulse PLa output to the thyristor rectifier 4 is automatically adjusted to perform under-excitation limitation, galvanometric compensation, and secondary control.

The adjustment section 10b is the same as the adjustment section 10a, and automatically adjusts the phase of the firing pulse PLb based on the output signal of the detection section 6b.

The switch 11 guides either the ignition pulse PLa or PLb to the thyristor rectifier 4.

Normally, the ignition pulse PLa is guided to the thyristor rectifier 4, and when the alarm Sa of the voltage balancing relay 9 is output or by a device (not shown), the detection unit 6a! 1IiII Part 1
When an abnormality of 0a is detected, it acts to guide the ignition pulse PLb to the thyristor rectifier 4.

In other words, in this excitation control device, PT7a, CT8a, detection section 6a, and adjustment section 10a are used as regular systems, and PT7b and CT
8b, the detection unit 6b, and the adjustment unit 10b as a standby system.Normally, excitation control is performed in the regular system, and if the regular system fails, the standby system is automatically activated. The structure is such that operation can be continued by switching to

(Problems to be Solved by the Invention) Next, the operation when a failure occurs in the regular system PT 7a of the above excitation control device will be described.

If the secondary voltage drops abnormally due to a failure of the PT7a itself or a disconnection or poor contact at the connection between the primary and secondary sides of the PT7a, the voltage balance relay 9 will output an alarm Sa and the switching device 11 will be activated. The switch is switched to standby operation, but generally it takes several tens of milliseconds to several hundred milliseconds from the time the secondary voltage of the PT 7a drops until the switching of the switch 11 is completed. During this time, as the secondary voltage of PT7a decreases, the signal Va also decreases, so the phase of the ignition pulse PLa rapidly advances due to the action of the adjustment section 10a.

That is, the adjustment unit 10a determines that the terminal voltage of the synchronous generator 1 has decreased due to the decrease in the signal Va, and adjusts the phase of the firing pulse to increase the output voltage of the thyristor rectifier 4 in order to restore this to the target value. will proceed.

As a result, the output voltage of the thyristor rectifier 4 increases rapidly,
The terminal voltage of the synchronous generator 1 increases regardless of the target value.

When the switching of the switching device 11 is completed, the operation is switched to the standby system, the terminal voltage of the synchronous generator I is pulled back to the target value, and normal operation can be continued from then on.

As explained above, when a failure occurs in which the secondary voltage of the PT7a decreases, the state is uncontrolled for several tens to hundreds of milliseconds from the time the failure occurs until the switch 11 completes switching. This will adversely affect the operating state of the synchronous Ill.

Next, the operation when a failure occurs in the CT 8a will be explained. When the secondary current drops abnormally due to a failure of the C-choice 8a itself or a disconnection or poor contact at the secondary side of the C-choice 8a, the signal Ia, signal Pa, and signal output from the detection section 6a Since Qa decreases, the adjustment section 10a
Among the functions performed by the controller, output overcurrent limitations, underexcitation limitations, galvanometric compensation, etc. will no longer function properly.

As explained above, in the conventional excitation control device described above, despite having a duplex configuration to improve reliability,
If a failure occurs in the PT or CT used to detect the controlled variable, it may have an adverse effect on the synchronous generator, which is the device to be controlled, and some of the functions of the control device may be lost. There were drawbacks.

The present invention eliminates the above-mentioned conventional drawbacks and provides a sensor (in the above-mentioned conventional example, PT, C
It is an object of the present invention to provide a highly reliable automatic control device that can eliminate an adverse effect on equipment to be controlled and maintain the functions of the control device even if a failure occurs.

[Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, the present invention provides a system in which the absolute value of the outputs of a plurality of sets of detection units that detect controlled quantities of a controlled device is An absolute value high selection section that selects and outputs the larger one is provided, and the adjustment section outputs the manipulated variable to the device to be controlled based on the output signal.

(Function) Normally, the signals output from the two sets of detection sections show the same value, and the controlled variable is controlled to match the target value by the function of the adjustment section.

Even if a wire break or contact failure occurs on one input side of the two sets of detection sections and the detection signal thereof indicates zero, the absolute value high selection section selects and outputs a high value signal indicating a normal value.

That is, the normal signal is selected because the absolute value of the normal signal always shows a higher value than the absolute value of the abnormal signal, regardless of whether the controlled quantity is a positive or negative value.

As a result, the controlled variable can continue to be controlled so as to match the target value by the function of the adjusting section.

(Embodiment) FIG. 1 shows an embodiment in which the present invention is applied to an excitation control device. In this figure, the same parts as those of the conventional excitation control device explained in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted.

The absolute value high selection unit 12 selects the one with the larger absolute value between the signal Va and the signal vb, outputs the signal V, and similarly outputs the signal Ia.
and signal Ib, signal P from signal Pa and signal pb, and signal Q from signal Qa and signal Qb, the one with the larger absolute value is selected and output.

The adjustment section 10 performs excitation control of the synchronous machine 1 based on the output signal of the absolute value high selection section 12, and controls the terminal voltage mentioned above so that it matches the target value, and also controls the output overcurrent. limitations or under-excitation limitations.

The phase of the firing pulse PL output to the thyristor rectifier 4 is automatically adjusted to perform cross current compensation and secondary side control.

FIG. 2 is a block diagram for explaining the operation of the absolute value high selection section 12, and shows a portion that selects the one with a larger absolute value between the signal Qa and the signal Qb and outputs the signal Q.

The absolute value calculation unit 14a inputs the signal Qa, calculates its absolute value, outputs the signal IQal, and the absolute value calculation unit 14b
takes the signal Qb as input, calculates its absolute value, and calculates the signal IQ
Output bl.

The comparator 15 compares the signal 1Qal and the signal IQbl, and
When Qa>1Qbl, the selection signal SE is enabled and 1Q
When al≦Qbl, the selection signal SE is invalidated.

The selection unit 16 selects the signal Qa and outputs it as the signal Q when the selection signal SE is valid, and when the selection signal SE is invalid,
Since signal Qb is selected and output as signal Q, signal Q
As a result, the signal Qa and the signal Qb having a larger absolute value are selected and output.

With the above configuration, the operation when a failure occurs in the PT 7a of the excitation control device will be described.

If a failure occurs in the PT 7a itself or a disconnection or poor contact occurs in the connection between the primary and secondary sides of the PT 7a, and the secondary voltage drops abnormally, the signal Va also drops in proportion to the breakdown.

However, in the absolute value high selection section 12, the signal vb indicating the normal value
Since the signal V is continuously selected and output as the signal V, the signal V is not affected by the abnormality and normal operation can be continued.

Next, the operation when a failure occurs in the CT 8a will be explained.

If a failure occurs in the CT 8a itself or a disconnection or poor contact occurs in the connection portion on the secondary side of the CT 8a, and the secondary current decreases abnormally, the signals Ia, Pa, and Qa will decrease. Among these, the signal Qa is the polarity of the reactive power output from the synchronous machine 1,
That is, since it has a property of showing positive and negative polarity depending on whether the phase is leading or slowing, the absolute value will decrease when CT8a is abnormal.

At this time, the absolute value high selection unit 12 selects and outputs the higher absolute value, so the signal Ib and the signal pb indicating the normal value are output.
, signal Qb is selected and output to the signal engineer, signal P, and signal Q, so normal operation can be continued without being affected by the abnormality of CT8a.

As a result, PT7a, PT7b, CT8a, CT8b
Even if a failure occurs and the output signal of the detection unit 6a or 6b shows an abnormal value, the absolute value high selection unit 12 selects a normal signal, so that the synchronous machine I is not affected by the failure. normal operation can continue.

Note that although the above description describes typical embodiments of the present invention, the present invention is not limited thereto.

For example, the detection section 6a and the detection section 6b of the embodiment shown in FIG.
A plurality of sets of the absolute value high selection section 12 and the adjustment section 1o may be provided, and the output of the adjustment section 10 may be outputted by selecting a high value.

Further, in the embodiment, the terminal voltage, output voltage, active power, and reactive power of the synchronous generator are used as the controlled quantities, but in addition to these, field voltage and field current may be used.

In addition, although the embodiment has been described as an example in which the present invention is applied to an excitation control device for a synchronous generator, it is also possible to apply the present invention to automatic control devices in general such as process control devices. Differences in control methods such as fixed value control and follow-up control do not change the gist of the present invention.

[Effects of the Invention] As explained above, according to the present invention, there are a plurality of sets of detection units that detect a controlled device of a device to be controlled, and an absolute detection unit that selects and outputs the one with a larger absolute value among the outputs. Since the value/high selector is provided and the manipulated variable is output to the controlled device based on the output signal of the absolute value/high selector, the absolute value of the detected value of the controlled variable having positive and negative polarities decreases. Even if a failure occurs, a highly reliable automatic control device that can continue to control the equipment to be controlled without being affected by the failure can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an excitation control device showing an embodiment of the present invention, Fig. 2 is a block diagram for explaining the operation of the absolute value high selection section, and Fig. 3 is a block diagram of a conventional excitation control device. It is. 6a, 6b...detection section, 10...adjustment section, 12...
- Absolute value high selection section. Figure 1 Agent Patent Attorney Crest 1) Makoto

Claims (1)

[Claims] a plurality of sets of detection units that detect one or more controlled quantities of the controlled device; an absolute value high selection unit that selects and outputs the one with a larger absolute value among the outputs of each of these detection units;
An automatic control device comprising: an adjustment section that outputs a manipulated variable to the device to be controlled based on the output of the absolute value height selection section.