JPH05300800A - Excitation controller - Google Patents

Abstract

PURPOSE:To prove a stable excitation control irrespective of a rotating speed change of a synchronous machine by providing a speed detector for detecting a variation in the speed of the machine, and providing means for so varying a control function of an automatic voltage regulator in response to an output of the detector as to stabilize an excitation control system. CONSTITUTION:A difference between a voltage detection signal D of a voltage detector 6 which inputs a terminal voltage of a synchronous machine 1 through a transformer 7 for an instrument and a voltage set signal R by a voltage setter 9 is obtained by a comparator 8, and its error signal E is input to a voltage controller 12. A rotating speed of the machine 1 is detected by a speed detector 14 based on a pulse signal SS generated from a speed detection generator 13, and input to the controller 12. The controller 12 amplifies the signal E, phase-improves to stabilize a control system to output a voltage control signal C, and continuously varies an amplifying function in response to a speed signal N. A thyristor rectifier 4 is controlled by the signal C through a phase controller 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excitation controller used for controlling the terminal voltage of a synchronous machine.

[0002]

2. Description of the Related Art Generally, a synchronous machine is provided with an excitation controller for controlling its terminal voltage to be constant. Explaining this type of excitation control device with reference to FIG. 3, first, a field current is supplied to the field winding 1A of the synchronous machine 1 from the AC exciter 3 via the rotary rectifier 2. A field current is supplied to the field winding 3A of the AC exciter 3 from the thyristor rectifier 4, and the AC power supply of the thyristor rectifier 4 is supplied from the output of the synchronous machine 1 via the excitation transformer 5.

Here, the synchronous machine 1 is a rotary excitation type, and the AC exciter 3 is a rotary armature type synchronous machine. The field winding 1A of the synchronous machine 1, the rotary rectifier 2, and the armature of the AC exciter 3 are used. Is a structure of a brushless synchronous machine (indicated by a broken line in the figure) that rotates integrally.

On the other hand, the voltage detector 6 inputs the terminal voltage of the synchronous machine 1 through the instrument transformer 7, and outputs a voltage detection signal D proportional to this input to the comparator 8. The comparison unit 8 outputs the difference between the voltage setting signal R output by the voltage setting unit 9 and the voltage detection signal D as an error signal E. The voltage control unit 10 amplifies the error signal E, performs phase compensation for stabilizing the control system, and outputs the voltage control signal C. The phase controller 11 outputs a gate pulse PL having a phase corresponding to the voltage control signal C to the thyristor rectifier 4.

In the excitation control device having the above-mentioned configuration, the terminal voltage of the synchronous machine 1 is detected as the voltage detection signal D, the error signal E as a difference from the voltage setting signal R is amplified and phase compensated, and the thyristor rectifier 4 is supplied with the error signal E. Since the phase of the gate pulse PL is controlled, the terminal voltage of the synchronous machine 1 is controlled so as to match the voltage setting signal R.

Further, in the case of a disturbance such as a change in the terminal voltage of the synchronous machine 1, for example, when the load of the synchronous machine 1 is changed or the voltage setting section 9 is operated to change the value of the voltage setting signal R. The functions of amplification and phase compensation of the voltage controller 10 are adjusted so that the terminal voltage of the synchronous machine 1 quickly and stably coincides with the voltage setting signal R.

[0007]

However, in such a conventional excitation control device, there may be a problem in the operation when the rotational speed of the synchronous machine 1 changes.

Generally, the synchronous machine 1 is operated in parallel with the electric power system and is operated at the rated synchronous speed at that time, but it may be operated at a rotational speed other than the rated synchronous speed as a special operating state. For example, when the synchronous machine 1 is in parallel with the electric power system and is performing load operation, if the load is cut off due to an accident in the electric power system, the rotational speed of the synchronous machine 1 temporarily increases.

Further, even when the synchronous machine 1 is operated in a single load system without being connected in parallel with the power system, the rotational speed may change due to factors such as load fluctuations and abnormalities in the device for controlling the rotational speed. There is.

The terminal voltage of the synchronous machine 1 is proportional to the field current flowing in the field winding 1A and the rotation speed of the synchronous machine 1, respectively. Similarly, the output voltage of the AC exciter 3 is the field winding 3
It is proportional to the field current flowing in A and the rotation speed of the AC exciter 3, that is, the rotation speed of the synchronous machine 1. Therefore,
When the rotation speed of the synchronous machine 1 changes as described above, it greatly affects the operation of the excitation control device.

For example, when the rotation speed of the synchronous machine 1 increases, the ratio of the field current flowing through the field winding 1A to the terminal voltage of the synchronous machine 1 increases in proportion to the increase in the rotation speed. Similarly, the ratio of the field current flowing in the field winding 3A of the AC exciter 3 to the output voltage of the AC exciter 3 increases in proportion to the increase in the rotation speed, and as a result, the field winding 3A. And the ratio of the terminal voltage of the synchronous machine 1 increase in proportion to the square of the increase of the rotation speed.

As a result, the amplification factor of the open loop transfer function of the excitation control system increases in proportion to the square of the increase of the rotation speed, so that the operation of the control system becomes unstable depending on the degree of increase of the rotation speed. There is.

Therefore, an object of the present invention is to provide an excitation control device capable of stably controlling the terminal voltage of a synchronous machine even if the rotation speed of the synchronous machine changes.

[0014]

SUMMARY OF THE INVENTION The present invention is based on a synchronous machine, an automatic voltage adjusting section for controlling the terminal voltage of the synchronous machine to be constant, and a synchronous signal based on a control signal output from the automatic voltage adjusting section. In the excitation control device that supplies a field current to the field winding of the machine to form an excitation control system, a subtraction unit that subtracts a terminal voltage output from the synchronous machine and a set terminal voltage, and outputs a deviation voltage, , Detecting the rotation speed of the synchronous machine, changing the control function of the automatic voltage adjusting unit according to the speed detection unit that outputs a speed signal according to the rotation speed, and the speed signal,
A means for calculating the deviation voltage according to the control function and outputting the control signal is provided.

[0015]

With the above construction, the control function of the automatic voltage adjusting unit changes so that the control system becomes stable according to the speed signal of the synchronous machine. Therefore, even if the rotational speed of the synchronous machine changes and the transfer characteristics of the synchronous machine and the exciter change, the open loop transfer function of the excitation control system does not change significantly, so that the terminal voltage of the synchronous machine can be controlled stably. it can.

[0016]

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

FIG. 1 is a block diagram of an excitation controller showing an embodiment of the present invention. In FIG. 1, the same parts as those of the conventional example shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. 1 is different from FIG. 3 in that the voltage control unit 10 is a voltage control unit 12 having a different configuration, and in addition, the speed detection generator 1
3 and the speed detection unit 14 are additionally provided.

The speed detection generator 13 is installed close to a gear (not shown) provided on the rotary shaft of the synchronous machine 1, and generates a pulse signal SS having a frequency proportional to the rotational speed of the synchronous machine 1. is there. The speed detection unit 14 uses the pulse signal SS
Is input and the speed signal N proportional to the rotation speed of the synchronous machine 1
Is output. The signal level of the speed signal N is 1.0 when the rotational speed of the synchronous machine 1 is the rated synchronous speed.
Is output.

The voltage control unit 12 amplifies the error signal E, performs phase compensation for stabilizing the control system and outputs the voltage control signal C, and also inputs the speed signal N to obtain its value. Accordingly, the amplification function is continuously changed.

Here, the voltage control section 12 has an amplifying section 12a, a square calculating section 12b and a dividing section 12 as shown in FIG.
c and the phase compensator 12d. Amplifier 12a
Is a signal X obtained by proportionally amplifying the error signal E by the following equation (1).
Is output.

[0021]

[Equation 1] X = KE ………… (1)

Where K = proportional constant

The squaring unit 12b outputs a signal Y obtained by computing the speed signal N by the following equation (2).

[0024]

[Equation 2] Y = N ² ………… (2)

The division section 12c outputs the result of dividing the signal X by the signal Y as the signal Z by the following equation (3).

[0026]

(3) Z = X / Y = KE / N ² …………… (3)

The phase compensator 12d phase-compensates the signal Z and outputs a voltage control signal C.

In the above structure, the synchronous speed of the synchronous machine 1 is converted into the pulse signal SS by the speed detection generator 13 and input to the speed detection unit 14, and the speed detection unit 14 outputs the speed signal N to the square of the voltage control unit 12. It is input to the calculation unit 12b. In this case, when the rotational speed of the synchronous machine 1 is rated, 1.0 is output to the squaring calculation unit 12b as the speed signal N, and the above equation (1) is used.
Thus, the signal Y from the squaring unit 12b is input to the dividing unit 12c as 1.0. As a result, the amplifier 12a
Signal X and the signal Y of the square calculation unit 12b are divided by the above equation (3), and the same values of the signal X and the signal Z are input to the phase compensation unit 12d. Therefore, when the synchronous machine 1 is operating at the rated synchronous speed, the same operation as the conventional example is performed.

Next, when the rotation speed of the synchronous machine 1 rises, the speed signal N of the speed detecting section 14 becomes 1.0 or more,
This value is input to the square calculation unit 12b and squared. At this time, the voltage of the synchronous machine 1 also rises and the signal Y proportional to the square of the speed signal N is input to the amplification unit 12a of the voltage control unit 12. The division unit 12c outputs the signal Z obtained by dividing the signal X of the amplification unit 12a by the signal Y of the square calculation unit 12b according to the equation (3). As a result, the value of the signal Z becomes the same value as when the rotational speed of the synchronous machine 1 is the rated synchronous speed, and the phase control unit 11 outputs the gate pulse PL to the thyristor rectifier 4.

As described above, when the rotational speed of the synchronous machine 1 increases, the ratio of the terminal voltage of the field winding 3A to the terminal voltage of the synchronous machine 1 increases in proportion to the square of the increase in the rotational speed. Since the amplification factor of 12 is inversely proportional to the square of the rotation speed of the synchronous machine 1, the amplification factor of the open loop transfer function of the excitation control system is 1
It does not change even if the rotation speed of increases. Therefore, the operation of the control system can continue stable control without being affected by the change in the rotation speed of the synchronous machine 1.

In the above embodiment, the amplification factor of the voltage control unit 12 is continuously changed in inverse proportion to the square of the rotation speed of the synchronous machine 1. However, the present invention is not limited to this and simplification of the device is achieved. Therefore, the amplification factor may be switched stepwise. Also,
In the above embodiment, only the amplification factor of the voltage control unit 12 is changed according to the change of the rotation speed of the synchronous machine 1, but the same effect can be obtained by changing not only the amplification factor but also the phase compensation function. ..

In the above-mentioned embodiment, the present invention is applied to the brushless excitation system, which is greatly affected by the change in the rotation speed of the synchronous machine 1. However, the synchronous machine is not provided with an AC exciter and the output of the thyristor rectifier is used. It can also be applied to a thyristor excitation system that supplies a field current to the first field winding 1A.
In this case, it suffices if the amplification factor of the voltage control unit 12 is made inversely proportional to the rotation speed of the synchronous machine 1, and it is possible to easily cope with it by deleting the square calculation unit 12b.

Further, in the digital type control device to which the microprocessor which is widely used in recent years is applied, the change of the control function shown in this embodiment can be realized relatively easily. In this digital control device, the stability margin of the control system tends to decrease due to the signal detection time delay and the calculation time delay due to sampling, but since the effect of maintaining the stabilization is obtained by this embodiment, It is also possible to obtain the effect of facilitating the adoption of the digital control device.

[0034]

As described above, according to the present invention, the speed detecting unit for detecting the change in the rotational speed of the synchronous machine is provided, and the control function of the automatic voltage regulator stabilizes the excitation control system according to the output thereof. By providing the means for changing the rotation speed of the synchronous machine, stable excitation control is performed even if the rotation speed of the synchronous machine changes.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an excitation control device showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a voltage control unit of FIG.

FIG. 3 is a configuration diagram of an excitation control device corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Synchronous machine 2 Rotary rectifier 3 AC exciter 4 Thyristor rectifier 6 Voltage detection unit 8 Comparison unit 9 Voltage setting unit 11 Phase control unit 12 Voltage control unit 13 Speed detection generator 14 Speed detection unit

Claims (1)

[Claims] 1. A synchronous machine, an automatic voltage adjusting section for controlling a terminal voltage of the synchronous machine to be constant, and a field winding of the synchronous machine based on a control signal output from the automatic voltage adjusting section. In an excitation control device that supplies a magnetic current to form an excitation control system, a subtraction unit that subtracts a terminal voltage output from the synchronous machine and a set terminal voltage, and outputs a deviation voltage, and a rotation speed of the synchronous machine. And a speed detection unit that outputs a speed signal according to the rotation speed, and a control function of the automatic voltage adjustment unit is changed according to the speed signal, and the deviation voltage is calculated according to the control function. An excitation control device comprising means for outputting the control signal.