JPS6259560B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an excitation device for a synchronous machine,
In particular, it effectively corrects the field time constant.

In general, various models using small synchronous generators and coils simulating power transmission lines are made as model devices for analyzing various phenomena in power systems. It is desirable that the constants obtained are equal to those of large synchronous generators actually used by electric power companies.

However, when a synchronous machine is made smaller, its field resistance becomes relatively large, and the field time constant becomes 1/10 to 1/20.
There was a problem with the extent. Additionally, if the field winding is made thicker to reduce the field resistance, the inertia constant and other constants will no longer match those of a large machine, making it difficult to analyze the power system by improving the synchronous machine itself. was.

From this point of view, a method of adjusting the field time constant is known as a means of downsizing a synchronous machine and giving it the same functionality as a large machine. FIG. 1 is a block diagram for explaining the principle of this field time constant adjustment method. In the figure, 2 is a synchronous machine, 1A is the field winding of this synchronous machine 1, 1B is the field winding, 1A a detection winding provided in the same slot as and having the same number of turns to detect the number of magnetic flux linkages of the field winding 1A;
2 and 3 are amplifiers, and 4 is an adder.

In the above configuration, the detection winding 1B is provided in the same slot as the field winding 1A and is wound with the same number of turns, so its magnetic flux linkage number _SC
is equal to the magnetic flux linkage _f of the field winding 1A, and the output voltage V _SC of the detection winding 1B can be expressed by V _SC =d _f /dt (1) Equation (1). If the resistance of the field winding 1A is r _f and the field winding current is if, then the terminal voltage V _{f of} the field winding 1A is V _f = r _f i _f + d _f /dt...(2 ) is expressed by equation (2). Further, this terminal voltage V _f is calculated as follows, where the gain of amplifier 2 is set to A times the gain of amplifier 2 and the gain of amplifier 3 is set to (A-1)/A times with respect to the voltage _command V. A-1)/AV _SC }・A...(3) Since it is expressed by equation (3), by rearranging equations (1), (2), and (3), V=r _f / _Aif + d _f /dt...(4) Obtain equation (4). Comparing this equation (4) and equation (2), we get
It can be seen that the configuration shown in FIG. 1 responds to the voltage command V in the same way as a synchronous machine whose field resistance is r _f /A, and the smaller the field resistance, the longer the time constant. As described above, using the detection winding 1B wound with the same number of turns in the same slot as the field winding 1A, the output voltage V _SC and the voltage command V are input to the adder 4, and the field winding It is known in principle that the field time constant can be lengthened by controlling the voltage applied to 1A, _VC .

FIG. 2 shows a conventional embodiment based on the above-mentioned principle, and the same reference numerals as in FIG. 1 indicate corresponding parts.
Reference numeral 5 denotes a DC generator consisting of an excitation winding 5b and an armature 5c that receive the applied voltage from the amplifier 5a, and an induction motor 5d is generally used as driving means for the DC generator 5. .

The conventional example shown in FIG. 2 has the same configuration as that shown in FIG _. There is a problem that the response of _the output voltage V _f of the DC generator 5 to need to be raised. However, if the gain A is set large, the DC generator 5, the field winding 1A, and the detection winding 1
The gain A cannot be set large because the phase delay caused by the loop consisting of amplifier B, amplifier 3, and amplifier 5a will cause an oscillation phenomenon. Therefore, the second
Even if the excitation device shown in the figure is used, the field time constant is 1 to 2 times lower than that of a general synchronous machine that does not include a detection winding.
The length was only about twice as long, and it was impossible to improve the length to a level suitable for practical use. Moreover, since the DC generator 5 is used as the excitation device, maintenance is required and a large site is required.

3 shows another conventional example based on the principle of FIG. 1. In the figure, 6 is a field winding, 1A
The controlled rectifier means 6 is composed of a thyristor that provides a voltage signal V _f to the synchronous signal SYNC.
It is ignited by an ignition signal from the ignition signal generating means 7 which is synchronized with the command signal V _C and issued in accordance with the command signal V C . Further, 8 is a synchronous generator, and 9 is a drive means for the synchronous generator 8.

In the above configuration, when the input voltage V _C of the firing signal generation means 7 is changed, the firing phase of the thyristor of the control rectification means 6 is changed, and the output voltage V _f is changed. Therefore, the amplifying means for applying the voltage signal V _f to the field winding 1A operates in the same manner as the principle shown in FIG. However, if the frequency of the output voltage V _AC of the synchronous generator 8 is the commercial frequency (50 Hz, 60 Hz), the dead time of ignition control results in a slow response as a means of amplifying the width. As usual, we were unable to make sufficient improvements. Therefore, it is difficult to use a commercial power source instead of the synchronous generator 8, and it is necessary to use a high-frequency generator as the synchronous generator 8. In this way, even when using a controlled rectifier as shown in FIG. 3, a rotating machine called a high-frequency generator is required, so there are problems with maintenance, site, etc., as in the case of FIG. 2. or,
Since the ignition signal generating means 7 must generate a signal in synchronization with the synchronizing signal SYNC, it requires a very complicated circuit.

The present invention was made in order to eliminate the above-mentioned drawbacks of the conventional method.It does not use a rotating machine, has a simple configuration, does not require maintenance, site, etc., and has a field time constant that is higher than that of the conventional method. The purpose is to provide an excitation device for a synchronous machine that can last about 20 times as long.

Hereinafter, embodiments of the present invention will be explained based on the drawings. In FIG. 4, 10 is a transistor 10.
a, 10b, diodes 10c, 10d 2
In the phase transistor chopper circuit, a base control circuit 1 is provided at the base of the transistors 10a and 10b.
1 is connected. 12 is an amplification/low frequency circuit which inputs the output voltage V _SC of the detection winding 1B and amplifies it to a low frequency range, and converts the output voltage V _LPF into an adder 4.
supply to. Further, 13 is a DC power supply for the two-phase transistor chopper circuit 10, and other parts are the same as those of the conventional circuit.

In the configuration shown in FIG. 4, transistors 10a and 10b each have a conducting phase of 180
The operation is shifted by ゜ (half the time of the repetition cycle). Then, depending on the length of the conduction period, there will be a state in which both transistors 10a and 10b are conductive (referred to as a mode), a state in which only one of them is conductive (referred to as a mode), and a state in which both transistors are blocked. There are three types of states (referred to as modes). The output voltage V _f of the two-phase transistor chopper circuit 10 becomes the voltage E of the power supply 13 in the mode state, 0 in the mode state, and -E in the mode state.

Now, if the switching frequency of the transistor is f, and the conduction period of each transistor is set to 180 degrees or more, the two-phase transistor chopper circuit 10 can be operated by alternating modes.
As shown in Fig. 5a, the output voltage V _f is at a frequency 2f, which is twice the switching frequency f of the transistor.
, the part where the DC voltage is E (mode state)
The waveform has a periodic repeating of the zero period and the zero portion (mode state), and by changing the ratio of both periods, the average voltage applied to the field winding 1A is changed and the field current is controlled. can do.
This ratio changes under the control of the base control circuit 11 which provides a control signal to the transistor chopper circuit 10. In addition, in this case, by shortening the repetition period and increasing the repetition frequency, the response from when the output voltage V _C of the adder 4 is generated until the voltage V _f is supplied to the field winding 1A is as follows. Since the dead time can be reduced and accelerated, the delay in response does not become a problem as in the case of using the DC generator 5 shown in FIG. 2.

Furthermore, since the detection winding 1B is wound with the same number of turns in the same slot as the field winding 1A, when the rectangular wave voltage shown in FIG. 5a is applied to the field winding 1A, this detection winding Similarly to the voltage V _SC shown in FIG. 5B, the rectangular wave voltage shown in the line 1B is generated in addition to the rate of change of the magnetic flux linkage of the field winding 1A which is originally necessary for control. However, since this is due to transformer action, the DC component is excluded as shown in V _SC in Figure 5b. In this way, the output voltage V of the detection winding 1B
_SC becomes a rectangular wave voltage, and then its harmonic components, that is, rectangular wave components, are sufficiently removed by the low frequency circuit 12, resulting in a waveform like V _LPF in FIG. 5c, so that the rectangular wave component Therefore, the two-phase transistor chopper circuit 10 will not malfunction. In addition, the cutoff frequency of the low frequency circuit 12 is set to 1/40 to 1/10 of the rectangular wave output frequency of the two-phase transistor chopper circuit 10.
If it is set to 0, the gain A can be increased by 10 to 20 times, and the field time constant can be increased by 10 to 20 times. In addition, in the illustrated configuration, all the equipment is stationary and no rotating machine is used, so maintenance and space are unnecessary. Therefore, the entire device is extremely compact and suitable as a model device for a power system including a large number of synchronous machines.

In the configuration shown in FIG. 4, the detection winding 1B and the field winding 1A are arranged in the same slot and with the same number of turns, but as explained below,
The same effect can be obtained even if the ratio of the detection winding 1B and the field winding 1A of each slot is made equal. Figure 6 shows a cross section of the rotor field of a synchronous machine, where the turn ratio of the field winding 1A and the detection winding 1B provided in the slot of the field core 1C is 2:1. It is. In this case, the output of the detection winding 1B is equal to the rate of change d _f /dt of the magnetic flux linkage of the field winding 1A.
The value will be 1/2. Therefore, if the gain of the amplification/low-frequency circuit 12 is set to twice the gain when the turn ratios of the field winding 1A and the detection winding 1B are made equal, the configuration is similar to that shown in FIG. obtain the desired effect. Furthermore, by reducing the ratio of the detection winding 1B to the field winding 1A, the field winding 1A provided in the same slot as the detection winding 1B can be made thicker, and the field time constant becomes longer. , the gain A of the control circuit can be reduced. In addition, even if the detection winding 1B is omitted in slots where the influence is small, or if the detection winding 1B is provided in non-slot areas, the rate of change in the magnetic flux linkage of the field winding 1A, or the It goes without saying that a similar effect can be obtained if a proportional signal can be detected.

Furthermore, FIGS. 7 and 8 respectively show other embodiments of the present invention, and FIG. 7 shows a low-frequency active wave circuit 14 as a means for amplifying and lowering the detection signal by the detection winding 1B. This is an example of a configuration using . 7th
In the figure, the low-frequency active wave circuit 14 consists of an operational amplifier 14a, resistors 14b, 14c, 14d, and capacitors 14e, 14f, and further reduces the ripple component of the voltage V _LPF shown in FIG. It is possible to realize amplification/low frequency means that efficiently removes components and sufficiently passes necessary signals. On the other hand, FIG. 8 uses a single-phase transistor chopper circuit 15 as a semiconductor chopper circuit, and this single-phase transistor chopper circuit 15 has a transistor 15a.
and a diode 15b, and the field winding 1 is controlled by the switching control of the transistor 15a.
A rectangular wave voltage will be applied to A. In this case, unlike the two-phase transistor chopper circuit 10, the switching frequency of the transistor 15a and the switching frequency of the output voltage are equal, so in order to output the same frequency as in the two-phase case, the transistor 15a must be switched. It is necessary to switch at twice the frequency of the transistor in the two-phase case. However, since the number of components is halved, the device becomes smaller.

In the above embodiments, it goes without saying that the switching means of the chopper circuit may be a thyristor instead of a transistor, and the number of phases of the chopper circuit may be single-phase or multi-phase.

As described above, according to the present invention, it is possible to provide an excitation device for a synchronous machine that does not require maintenance or a site and can effectively correct the field time constant.

[Brief explanation of the drawing]

Fig. 1 is a block diagram for explaining the principle of the field time constant adjustment method used in the present invention, Figs. 2 and 3 are block diagrams showing the excitation device of a conventional synchronous machine, and Figs. 4 to 8 The figures show an embodiment of the present invention, and Fig. 4, Fig. 7, and Fig. 8 each show a configuration diagram, Fig. 5 is a voltage waveform diagram of each part of Fig. 4, and Fig. 6 is a synchronous machine. FIG. 1A: Field winding, 1B: Detection winding, 10,1
5: Semiconductor chopper circuit, 13: DC power supply, 1
2: Amplification/low frequency circuit, 14: Low frequency active wave circuit. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A semiconductor chopper circuit that switches a DC power source according to a switching command signal to supply a predetermined voltage to a field winding of a synchronous machine, and a semiconductor chopper circuit that switches a DC power supply according to a switching command signal and supplies a predetermined voltage to a field winding of a synchronous machine, and a rate of change in the magnetic flux linkage of the field winding. It is equipped with a detection winding for detection, and an amplification/low-frequency circuit that inputs the output voltage of the detection winding and amplifies/low-frequency the input. An excitation device for a synchronous machine, characterized in that the response time of the field circuit to the field voltage command signal is adjusted by providing a signal obtained by subtracting the output signal of the frequency range circuit as the switching command signal. 2. The first claim characterized in that the field winding and the detection winding are provided in the same slot, and the number of turns of the field winding and the detection winding in each slot is equal. Excitation device for the synchronous machine described in Section 1. 3. The excitation device for a synchronous machine according to claim 1 or 2, wherein the amplifying/low-frequency circuit is a low-frequency active wave circuit.