JPH0258880B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an excitation adjustment device for an alternator.

The output voltage of a generator fluctuates due to load changes such as load on/off. In particular, generators with high impedance, such as emergency generators, have large output voltage fluctuations due to load fluctuations, which adversely affects other loads supplied by the generator. Therefore, it is desired that a control device that controls the output voltage of the generator be able to control the generator output with good responsiveness even to rapid load changes. Furthermore, in a generator having a load such as a rectifier, the output voltage waveform is often distorted, and even in this case, it is desirable that the control device be able to stably control the generator output voltage. Furthermore, in the case of a marine generator, the generator is required to have the ability to continue flowing a specified current for a specified period of time even if the generator output is short-circuited, that is, to have compound winding characteristics.

FIG. 1 shows a conventional excitation adjustment device having the above-mentioned compound winding characteristic function. According to this, a winding transformer 3 having a current winding 31 , a voltage winding 32 and an output winding 33 is provided to supply power to the field winding 2 of the alternating current generator 1 . current winding 3
1 is inserted in series with the generator output line, and the voltage winding 3
2 is connected to a generator terminal via an AC reactor 4. A capacitor 5 is connected to a connection point between the voltage winding 32 and the AC reactor 4. A rectifier 6 is connected to the output winding 33, and a field winding 2 is connected between the DC output terminals of the rectifier 6. Furthermore, a thyristor 7 and a resistor 8 are connected between one phase terminal on the AC side and one terminal on the DC side of the rectifier 6.
A series circuit is connected to the overvoltage suppression circuit 9, and an overvoltage suppression circuit 9 is connected in parallel to this series circuit. The firing phase of the thyristor 7 is controlled by the control device 10 so that the generator terminal voltage matches the voltage setting value set by the voltage setting device 11.

The winding 32 of the voltage component circuit that provides the excitation necessary to generate the rated voltage at no-load and the winding 31 of the current component circuit that supplies the excitation that compensates for the voltage drop due to the load current during the load are magnetically coupled. I'm doing it,
A combined output of both appears at the output winding 33. A generator current or a current proportional to it flows through the winding 31 . The output voltage of the generator 1 is applied to the winding 32 via the reactor 4. The output of the winding 33 is rectified by the diode rectifier 6 and applied to the field winding 2 to cause a field current to flow. Voltage component is 4→3 from generator output
2 → 33 → 6 → 2, and the current component is 31 → 3
Add 3 → 6 → 2.

The voltage regulating shunt thyristor 7 is connected between one phase of the input circuit of the rectifier 6 and the negative electrode of the output of the rectifier 6 via a resistor 8. The excess current of the three-winding transformer required to obtain the desired output voltage of the generator is diverted to the alternating current side by firing this thyristor, so that it does not flow to the field circuit. Generally, the output current of a three-winding transformer is designed to be slightly larger than the required field current, so it is necessary to fire the thyristor every cycle to shunt the current. The divided flow to the thyristor, that is, the firing phase of the thyristor is determined by the generator voltage control device 10 and the generator voltage setting circuit 11.
The generator voltage is controlled to be at the set value.
The capacitor 5 is connected to make the reactor 4 resonate, thereby reducing the influence of the generator field resistance and making it easier to establish the voltage at the time of starting.

As mentioned above, the basics of the conventional method are three
Since the method uses a wire-wound transformer to magnetically couple the voltage element and the current element, it has the following drawbacks.

(1) A three-winding transformer is larger than a transformer of the same capacity.

(2) Output changes depending on the degree of coupling, so adjust the output (for example, adjust the gap of the AC reactor, the size of the thyristor series resistance, or the size of the capacitor)
It is necessary to do this.

Furthermore, since the conventional method uses a thyristor to shunt the current every cycle, when the thyristor is turned off, all the output current of the three-winding transformer must flow to the field circuit. The output of the three-winding transformer can be regarded as a constant current source, and the inductance of the field circuit is much larger than that of the generator circuit, so when the thyristor is turned off, a high voltage is generated in the field circuit. For this reason, the overvoltage suppression circuit 9 is connected, but since the loss generated by this circuit is large (the overvoltage suppression circuit 9 absorbs the current until the field circuit absorbs the current) There is also the drawback that the size of the market is increasing.

Further, the control device 10 controls the conduction rate of the diversion cycle so that the voltage of the generator matches the value of the generator voltage setting device 11, but in the conventional system, this control device uses a PI regulator to eliminate offset. It is configured. For this reason, even if the generator voltage suddenly changes due to a sudden change in load, etc., a control delay occurs because the control device is a PI regulator, making it difficult to obtain a sufficiently fast control response.

Furthermore, the shunt thyristor 7 must be fired in synchronization with the generator voltage. However, when a load such as a rectifier is connected to a generator, the output voltage of the generator becomes a distorted waveform due to the commutation of the rectifier.
Since the synchronization signal for firing the thyristor is derived from the generator output voltage, the synchronization signal fluctuates due to this distortion. For this reason, the conventional system has the disadvantage that control becomes unstable or even becomes impossible depending on the load condition.

The objects of the present invention are (1) to have a simple circuit structure and obtain compound winding characteristics, (2) to avoid the need for complicated adjustments, and (3) to operate a generator stably even if the voltage waveform of the generator is distorted. (4) Even if the generator voltage suddenly changes due to a sudden load change, the generator voltage can be returned to its original value faster than before, resulting in a stable generator voltage with less voltage fluctuation. An object of the present invention is to provide a generator excitation adjustment device.

The basics of the present invention are to rectify the output obtained by electrically combining voltage elements and current elements (vector combination) on the AC side with a rectifier, adding the output to a magnet circuit, and connecting a semiconductor switch between the DC terminals of the rectifier. In the main circuit configuration in which a part of the output current of the rectifier is diverted to this semiconductor switch, the control device is an average value control type generator voltage regulator and an instant value control type field current controller. The main feature is that the voltage adjustment function is quick-responsive.

Hereinafter, the present invention will be explained with reference to FIG. 2 and subsequent drawings.

FIG. 2 shows one embodiment of the present invention. According to this, the AC side terminal of the rectifier 101 for feeding power to the field winding 2 of the AC generator 1 is connected on the one hand to the secondary side of the power transformer 102 inserted into the output bus of the generator. , on the other hand, is connected to a generator terminal via an AC thyristor 103. AC reactor 1
03 serves as a voltage component circuit for extracting a component dependent on the generator voltage, and a power current transformer 10
2 serves as a current component circuit for extracting components dependent on the generator current. Both components are rectified by 10
Vector synthesis is performed on the AC input side of 1. The DC output current of the rectifier corresponds to the rectified composite current of both components. A controllable semiconductor switch 100 is connected between the DC output terminals of the rectifier 101, which makes it possible to shunt a portion of the DC output current of the rectifier. Rectifier 10
1 can be configured as a three-phase diode bridge, and the semiconductor switch 100 can be a transistor, a gate turn-off thyristor, or a thyristor chopper. A current absorption circuit 104 is connected in reverse series to the field winding 2 to which current is supplied from the rectifier 1 . A capacitor can be used as the current absorption circuit 104. This current absorption circuit 104 serves to absorb the difference current between the DC output current of the rectifier 101 and the field current when the semiconductor switch 100 is off. The conduction rate of the semiconductor switch is controlled by a control device to be described later, thereby adjusting the field current. Due to the voltage-dependent component and current-dependent component included in the DC output current of the rectifier 101, when the load fluctuates, it is possible to compensate for the load fluctuation with good responsiveness by changing the DC output current.

An embodiment in which a capacitor is used as the current absorption circuit 104 is shown in FIG. 3 only for the main circuit portion. According to FIG. 3, in addition to the capacitor 105 serving as a current absorption circuit, a backflow prevention diode 106 is inserted between this capacitor and the semiconductor switch 100. The other configurations are the same as in FIG. 2. The diode 106 connects the capacitor 10 when the semiconductor switch 100 is turned on.
5 is prevented from flowing through this semiconductor switch 100. This eliminates the risk of destruction of elements such as transistors used as the semiconductor switch 100. Further, a transformer 107 can be inserted between the AC reactor 103 and the generator as necessary.

Returning to FIG. 2 again, the control circuit portion will be explained. The actual value of the generator terminal voltage is detected by the voltage detector 20.
0, and the detected voltage actual value is led together with the voltage target value from the voltage setting device 202 to the average value control type voltage regulator 203, and the voltage regulator 203 adjusts the current according to the voltage control deviation. Form a target value. This current target value is compared in magnitude with the actual field current value detected by the current detector 201 in a current comparator 204 . Current comparator 20
Reference numeral 4 is constructed as a hysteresis comparator which generates an output signal of binary operation according to the magnitude relationship between the target value and the actual value of the field current. A control device 205 controls the semiconductor switch 100 to turn on and off in accordance with the binary operation output signal of the current comparator 204.

Next, the operation of the embodiment shown in FIG. 2 (or FIG. 3) will be explained with reference to the voltage and current waveforms of the main parts shown in FIGS. 4a and 4b.

The limited number of circuits is selected so that the output current i101 of the rectifier 101 is in any case larger than the required value of the field current _i2 . semiconductor switch 100
When is on, the rectifier output current i101 is bypassed by this semiconductor switch 100 and the field current _i2 decreases. As soon as the current i ₂ reaches the lower limit target value, the output signal of the current comparator 204 is inverted,
This reversal causes the controller 205 to turn off the semiconductor switch 100. By turning off semiconductor switch 100, rectifier output current i101 flows into the field winding circuit. Because the field current i ₂ can only increase gradually due to the field inductance, the difference current i
101-i ₂ flows into the current absorption circuit 104 (or capacitor 105). As soon as field current i ₂ reaches the upper target value, the output signal of current comparator 204 is inverted, which causes controller 205 to turn on semiconductor switch 100 . semiconductor switch 10
0 turns on, the rectifier current i101 is bypassed through this semiconductor switch, and the field current _i2 decreases. In this way, the field current i ₂ is
Instantaneous value control is performed to maintain the target value given by 03.

The conduction rate α of the switch 100 at a certain moment is determined by T _ON being the on time and T being the period.

It can be expressed as α=T _ON /T, and the average value I _F of the field current i ₂ is
If the average value of the rectifier output i101 is _I0 , then there is a relationship of I _F =(1-α) _I0 . In other words, if we look at it as an average value,
Of the output current I ₀ of the rectifier, the field is (1-α) I ₀
This means that the remaining αI ₀ is diverted to the flow switch 100.

Next, the operation when the generator voltage suddenly changes due to a sudden change in load will be explained with reference to FIG. When there is no load fluctuation (before t ₀ in the figure), the output voltage of the voltage regulator 203 and the output voltage of the field current detector 201 are compared, and the current comparator 204 outputs the output V204 as shown in the figure and switches the switch 100. is turned on and off to match the voltage of the generator 1 with the set voltage. When load fluctuation occurs, the following happens. The operation when the load suddenly changes will be explained in the case of sudden load increase (load injection).
When the load increases rapidly at time t ₀ , the output voltage of the generator drops. The output V200 of voltage detector 200 also drops. The voltage regulator 203 increases the output V203 in order to return the voltage of the generator 1 to its original state. A current comparator 204 converts the field current value into a voltage regulator 20.
It operates to match the outputs of 3. That is, the magnetizing current value is caused to respond almost instantaneously to the output of the voltage regulator 203. Furthermore, the increase in load current is increased by the rectifier 10.
Since it is added to the output i101 of 1, the behavior of the field current is very fast. The above description is based on the case of an increase in load, but since the same operation occurs in the case of a sudden decrease in load, the explanation will be omitted. As described above, according to the present invention, the current comparator can cause the field current to respond instantaneously to the output of the voltage regulator without any control delay, which greatly improves the fluctuation width and settling time of the generator voltage due to sudden changes in load compared to the conventional method. I can do it.

Furthermore, by adding a differentiator circuit 206 with a dead zone as in the embodiment shown in FIG. 6, detecting the generator terminal voltage and superimposing the signal obtained through this circuit 206 on the input of the voltage regulator, the control response can be further improved. can be increased. The characteristics of the differential circuit 206 with a dead zone are shown in FIG.
As can be seen from the dead band characteristics shown in , the generator voltage V ₁
Only when the dead band width ΔVg ₀ suddenly changes by an amount exceeding the dead band width ΔVg 0, an output signal V206 having an incompletely differentiated waveform corresponding to the amount of change is generated. This output signal is input to the voltage regulator 203 with a polarity that corrects the voltage of the generator.

As explained above, the configuration according to the present invention has the following effects.

(1) Since the current element and voltage element are vector-combined on the rectifier input side, the generator has compound winding characteristics, and the generator voltage control performance can be greatly improved.

(2) The main circuit components are power CT, reactor,
Since it consists of a rectifier, semiconductor switch, and capacitor, the circuit configuration is extremely simple, making it smaller, lighter, and cheaper than conventional types.

(3) Since no adjustment of the main circuit components is required, the cost can be further reduced.

(4) Stable voltage control is possible because it is not affected by generator voltage waveform distortion. In other words, it can be applied to any load.

(5) Since an instantaneous response current comparator is connected to the output of the voltage regulator as a control device for the semiconductor switch, the response speed of the control device is fast and the amount of voltage fluctuation can be made much smaller than in the past.

[Brief explanation of drawings]

Figure 1 is a block diagram showing a conventional embodiment, Figure 2 is a block diagram showing a conventional embodiment.
The figure is a block diagram showing an embodiment of the present invention, FIG. 3 is a connection diagram showing an example of the configuration of the main circuit section in the embodiment of the present invention, and FIGS. 4 and 5 are waveform diagrams for explaining the operation of the present invention. FIG. 6 is a block diagram showing another embodiment of the present invention, and FIG. 7 is an operating waveform/input/output characteristic diagram for explaining the embodiment of FIG. 6. DESCRIPTION OF SYMBOLS 1... Generator, 2... Field winding, 100... Semiconductor switch, 101... Rectifier, 102... Power current transformer, 103... AC reactor, 104
...Current absorption circuit, 200 ...Voltage detector, 20
2... Voltage setting device, 203... Voltage regulator, 20
4...Current comparator, 205...Control device, 206
... Differential circuit with dead band.

Claims (1)

[Scope of Claims] 1. An AC reactor 103 for extracting a component dependent on the terminal voltage of the AC generator 1; A power current transformer 102 for extracting a component dependent on the output current of the AC generator 1; Both components. a rectifier 101 that rectifies a vector-combined current and supplies it to the field winding 2; a semiconductor switch 100 that is connected between the DC output side terminals of the rectifier 101 and that can be turned on and off; and an AC generator. a current absorbing capacitor 105 connected in parallel to the field winding 2 of the generator 1; a reverse current prevention diode 106 inserted between the semiconductor switch 100 and the current absorbing capacitor 105; and a terminal of the alternator 1. A voltage detection circuit 202 that detects the actual value of voltage; and a voltage adjustment device that receives the output signal of the voltage detection circuit 202 as a feedback signal and forms a field current target value in order to adjust the terminal voltage of the alternator 2 to a desired value. a current comparator 204 that compares the field current target value from the voltage regulator 203 and the actual field current value detected by the voltage detection circuit 202 to generate a binary operating output signal. An excitation adjustment device for an alternator, comprising: a control circuit 205 that performs on/off control of the semiconductor switch 100 according to a binary operation output signal of the current comparator 204.