JPH08116697A - Overload limiter of synchronous machine - Google Patents

Abstract

PURPOSE: To stabilize power system by sufficiently supplying reactive power to a system load. CONSTITUTION: An overload limiter of synchronous machine comprises a detecting means 5 for detecting actual armature current of a synchronous machine 1 and a limit initiation timing automatic control means 19 for automatically changing limit initiating timing for excitation of a synchronous machine 1 depending on amplitude of the actual armature current detected by such detecting means 5. An armature current can be applied up to the value near the limit capacity of the armature coil exceeding the rated armature current. Thereby, the synchronous machine is capable of supplying more current and reactive power to a system load and sufficiently ensuring the stability of the power system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor which prevents an armature current flowing in an armature winding of a synchronous machine from becoming an overcurrent due to an increase in reactive power or the like, thereby lowering the insulation of the armature winding. The present invention relates to an overload limiting device for a machine.

[0002]

2. Description of the Related Art A conventional synchronous machine overload limiting device is shown in FIG.
0 to 14 will be described. FIG. 10 is a connection diagram showing an overload limiting device in a synchronous machine such as a conventional synchronous generator and a synchronous phase shifter, and FIG. 11 is a supply active power, a reactive reactive power, a field control, a rated armature current, and an actual synchronous machine. 12 and 13 are diagrams showing the respective relationships of the armature current,
A diagram showing the relationship between the rated armature current, the actual armature current, and the field weakening control start when the overload limit start time (field weakening control start time) is different. FIG. 14 shows the rated armature current and the actual In the diagram showing the relationship between armature current and field weakening control start and the withstand capacity of the armature winding, the time point when the actual armature current exceeds the rated armature current is 0 point on the time axis. It is shown as.

In FIG. 10, 1 is a synchronous machine, 2 is a field winding of the synchronous machine 1, 3 is an instrument transformer for detecting the output terminal voltage of the synchronous machine 1, 4 is an automatic voltage regulator (hereinafter ,
The current of the field winding 2, that is, the field current is automatically controlled. Reference numeral 5 is a current transformer for an instrument that detects the armature current of the synchronous machine 1, 6 is an AC / DC converter that converts the output AC of the instrument current transformer 5 into a DC current,
7 is an armature current limit start value setter, 8 is a deviation detector,
The output of the AC / DC converter 6 is compared with the set output of the armature current limit start value setting device 7. Reference numeral 9 is an amplifier circuit for amplifying the output of the deviation detector 8, 10 is a power factor detector, which inputs the output AC voltage of the instrument transformer 3 and the output current of the instrument current transformer 5, The phase of the output AC voltage and the output current is detected. Reference numeral 11 is a polarity switching device for inputting the output of the power factor detector 10. 12 is a power system to which active power and reactive power are supplied from the synchronous machine 1, I _AR is an armature current of the synchronous machine 1,
E is the output terminal voltage of the synchronous machine 1, _IF is the synchronous machine 1
Is the field current of the field winding 2.

In FIG. 11, P on the horizontal axis is active power, Q on the vertical axis is reactive power, P ₁ is active power being supplied to the power system 12 by the synchronous machine 1, and Q ₁₁ is power system by the synchronous machine 1. 12
The case where the request for the reactive power from the power grid 12 is small for the reactive power supplied to Q ₁₂ is the reactive power supplied to the power system 12 by the synchronous machine 1, and shows the case where the request for the reactive power from the power system 12 is larger than the Q ₁₁ .
I _AR11 is an actual armature current of the synchronous machine 1 when the synchronous machine 1 is supplying the active power P ₁ and the reactive power Q ₁₁ to the power system 12, and I _AR12 is the active power of the synchronous machine 1 to the power system 12 by I _AR12. P ₁ ,
The actual armature current of the synchronous machine 1, when supplying the reactive power Q ₁₂ , I _AT is the rated armature current curve of the synchronous machine 1.

In FIGS. 12 to 14, t on the horizontal axis represents time, I _{A on} the vertical axis represents armature current of the synchronous machine 1, I _AR11 , I.
_AR12 and I _AT are the I _AR11 , I _AR12 and I _AT shown in FIG.
Is the same as the armature current, and t ₁ is the armature current from I _AR11 to I
_{When the} armature current I _AR12 exceeds the rated armature current I _AT , t ₂ is a time point at which the armature current I _AR12 starts changing to _{AR 12} , and t ₃ is a time point after a predetermined time T from the time point t ₂ . In FIG. 14, A _TL is a resistance curve of the armature winding, and shows a limit value at which the armature winding starts to cause an abnormality such as insulation deterioration as a relationship between the armature current and time.

Next, an overload limiting operation for preventing insulation deterioration of the armature winding of the synchronous machine 1 by field control when the reactive power of the power system 12 changes will be described. Power system 1
The load 2 includes an inductive load such as an electric motor and an electric furnace. This inductive load causes a phase delay in the power system 12 and requests the synchronous machine 1 to supply reactive power. The synchronous machine 1 supplies the reactive power to the power system 12 in response to the request for the reactive power supply, and the armature current I _AR of the synchronous machine 1 increases with the supply of the reactive power. If the armature current I _AR increases and exceeds the rated current I _AT of the armature winding, the armature winding is overloaded and the armature current I _AR
As the temperature of the armature winding rises, the insulation of the armature winding lowers. Accordingly, the armature current I _AR of the synchronous machine 1 if exceeds the rated current I _AT of the armature winding, and field weakening control the field current I _F of the field winding 2 of the synchronous machine 1, the armature current I _{The AR} is controlled so as to be within the rated current I _AT .

The control of such a conventional device is shown in FIGS.
4 will be described in detail. First, in FIG.
The AVR 4 controls the field current I _F of the field winding 2 according to the terminal voltage E of the synchronous machine 1 detected via the transformer 3 for instruments, and the synchronization is achieved even if the load of the system 12 changes. The terminal voltage E of the machine 1 is controlled to be constant. The output current of the synchronous machine 1, that is, the actual armature current I _AR is detected as a direct current by the AC / DC converter 6 via the instrument current transformer 5, and this direct current is detected by the deviation detector 8 According to the set value of the armature current limit start value setter 7, that is, the rated armature current I
_AT , and the direct current, that is, the actual armature current I
_{If AR} is larger than the rated armature current I _AT , the deviation signal of both is output from the deviation detector 8. The deviation signal output from the deviation detector 8 is amplified to a signal of an appropriate level via the amplifier circuit 9 and then supplied to the mixer (not shown) of the AVR 4 via the polarity switcher 11. . On the other hand, the power factor at the output end of the synchronous machine 1 is detected by a power factor detector 10 to which the output of the instrument transformer 3 and the output of the instrument current transformer 5 are supplied. ,
If the detected power factor is in the lag phase, a switching command is given to the polarity switcher 11 so that the polarity switcher 11 outputs the field weakening control polarity. Conversely, if the detected power factor is in the lag phase,
A switching command is given to the polarity switching device 11 so that the polarity switching device 11 outputs with a polarity for performing the strong field control. Therefore, the polarity switcher 11 outputs the deviation signal between the actual armature current I _AR and the rated armature current I _AT supplied from the amplifier circuit 9 to the field weakening control when the power factor is in the lag phase. Is supplied to a mixer (not shown) of the AVR4 with a polarity (for example, −polarity) to be performed, and conversely, when the power factor is in a leading phase, a polarity (for example, + polarity) for performing the strong field control
Then, it is supplied to the mixer of the AVR4. The AVR 4, when the deviation signal between the actual armature current I _AR and the rated armature current I _AT is supplied from the polarity switcher 11 with a polarity (for example, −polarity) for performing the field weakening control, The field current I _F to the field winding 2 of the synchronous machine 1 is reduced, demagnetization is controlled, and conversely, the actual armature current I _{AR is} controlled with a polarity (for example, + polarity) for performing the strong field control. When a deviation signal between the rated armature current I _AT and the rated armature current I _AT is supplied, the field current I _F to the field winding 2 of the synchronous machine 1 is increased to control the magnetization.

Next, these control operations will be described with reference to FIGS.
2 will be described. In FIG. 11 and FIG. 12, when the demand of the grid 12 is active power P ₁ and reactive power Q ₁₁ ,
Since the actual armature current I _AR is I _AR11 and is within the rated armature current I _AT , the output of the deviation detector 8 and the amplifier circuit 9 is 0, which corresponds to the actual armature current I _AR . field current I _F control is not performed. Next, when the reactive power Q starts to increase from the time point t ₁ due to the demand of the grid 12, the actual armature current I _AR11 also starts to increase from the time point t ₁ and the reactive power Q becomes Q ₁₂ at the time point t ₂ . When increased, the actual armature current I _AR becomes I _AR12 , and the rated armature current I _AT
Therefore, the deviation detector 8 outputs a deviation signal between the actual armature current I _AR12 and the rated armature current I _AT .
On the other hand, in the case of the reactive power Q ₁₂ , the power factor is in the lag phase, so the power factor detector 10 supplies the polarity switching device 11 with a command signal for switching to the field weakening polarity. Therefore, the AVR 4 controls the field current I _F in the direction of decreasing based on the polarity signal for weakening the field from the polarity switcher 11 and the output of the amplifier 9. By this control, if the field current I _F decreases, the reactive power Q ₁₂ begins to decrease in the direction of the reactive power Q ₁₁ as shown by the arrow, and the actual armature current I _AR12 also decreases, and the rated armature is reduced. Enter the current I _AT .

FIG. 13 shows an example in which, in the conventional device, the field current I _F is controlled to decrease when a predetermined time T elapses from the time t ₂ when the actual armature current I _AR12 exceeds the rated armature current I _AT. In this figure, I _ART is an actual armature current when a predetermined time T has elapsed from the time point t ₂ ,
Similar to the case where the field current I _F is controlled to decrease at the time point t ₂ , the rated armature current I _AT is entered by the decrease control of the field current I _F. Note that the circuit configuration of this case is not shown in FIG. 10 because the timer is provided between the deviation detector 8 and the amplifier 9 in FIG. 10 and other portions are the same as those in FIG. 10.

By the way, the insulation of the armature winding of the synchronous machine 1 can be continued for a long time as long as the actual armature current I _AR flowing through the armature winding is within the rated armature current I _AT. Of course, it does not decrease, but even if the actual armature current I _AR exceeds the rated armature current I _AT , it does not decrease depending on the flowing time.
Limit insulation of the armature winding does not decrease, depending on the actual armature current I _AR measurement and said actual armature current I _AR flows time when, as an armature winding tolerance curve A _TL 14 It is shown. In FIG. 14, t ₂ is the value shown in FIG.
Is the same as the time t ₂ at, and the actual armature current I
_This is the field weakening control start time (overload limit start time) in the case where the field weakening control is immediately started when _AR12 exceeds the rated armature current I _AT . t ₃ is the time point t ₃ in FIG. 13 described above.
_Is the same as the above, and is the field weakening control start time of the case where the field current I _F is controlled to decrease when a predetermined time T elapses from the time t ₂ when the actual armature current I _AR12 exceeds the rated armature current I _AT , t _3T is the time when the actual armature current I _ART enters the rated armature current I _AT by starting the field weakening control after the lapse of a predetermined time T.

Here, the actual armature current I at the time points of starting the field weakening control (starting points of overload limitation) t ₂ and t ₃ .
_{When AR12} and I _ART are compared with the armature winding withstand curve A _TL , the actual armature currents I _AR12 and I _ART are both within the armature winding withstand capacity (shaded area below the withstand curve A _TL). )It is in. That is, cases where the actual armature current I _{AR 12} described above starts field weakening immediately exceeds the rated armature current I _AT, and the actual armature current I _{AR 12} is rated armature current I _AT
In any of the cases in which the field weakening control is started when the predetermined time T elapses from the time t ₂ that exceeds the time t2, the actual armature currents I _AR12 and I _ART at the time when the field weakening control is started are continuously armature for a long time. Even if it flows through the winding, there is no fear that the insulation of the armature winding will deteriorate.

From a different point of view, as can be seen from FIG. 14, a field weakening control is immediately started when the rated armature current I _AT is exceeded, and a field weakening control is started when a predetermined time T elapses. In any of the above cases, the region surrounded by the armature current straight line L _ART that continuously flows the actual armature current I _ART at time t _3j and the armature winding withstand curve A _TL (the armature winding margin). It can be said that region B) is not utilized for reactive power supply to the grid load, and conversely,
It can be said that the system can be further stabilized by taking measures to positively utilize the armature winding margin area B and further continuously supplying the reactive power to the system load. In addition, as a means for preventing the field winding from burning due to an overcurrent caused by the current flowing through the generator field winding, a field current detecting means,
When the field current detected by the field current detection means is larger than a predetermined limit value, the circuit of the field winding provided in the AC exciter is opened to stop the excitation of the field winding of the generator. An overexcitation limiting device (not an overload limiting device for preventing overload on the armature winding) provided with a relay is disclosed in Japanese Patent Laid-Open No. 4-54822.

[0013]

As described above, in the conventional overload limiting device for a synchronous machine, the armature current setting circuit 7 for starting the field weakening control for limiting the reactive power supply to the grid is performed. The set value is fixed, and also at the time of starting the field weakening control (start of overload limitation), it is fixed immediately or after a fixed time when the actual armature current I _AR exceeds the rated armature current I _AT . Since the armature winding margin area B determined by the armature winding tolerance curve A _TL is not actively used for reactive power supply to the grid, the synchronous machine still has a reactive power supply capacity. Nevertheless, there is a problem in that it cannot fully meet the demand for reactive power from the grid. The present invention has been made to solve the problems in the conventional device as described above, and positively utilizes the armature winding margin area B defined by the armature winding withstanding curve for power supply to the grid. Therefore, it is an object of the present invention to provide an overload limiting device for a synchronous machine that can sufficiently exhibit the power supply capability of the synchronous machine and can sufficiently meet the power demand from the grid.

[0014]

According to a first aspect of the present invention, there is provided an overload limiting device for a synchronous machine, a detecting means for detecting the actual armature current, and an actual armature current detected by the detecting means. The limit start timing automatic control means for automatically changing the limit start timing of the excitation according to the magnitude of the above is provided. According to another aspect of the present invention, there is provided an overload limiting device for a synchronous machine, wherein the detecting means for detecting the actual armature current, and the armature winding according to the magnitude of the actual armature current detected by the detecting means. A limit start timing automatic control means for automatically changing the overload allowable time of the line is provided.

In the overload limiting device for a synchronous machine according to a third aspect of the present invention, the limitation start timing of the excitation is set according to the actual magnitude of the armature current when the synchronous machine is not connected to a load. Automatic control means for automatically changing the limit start time for no load, and for automatically setting the limit start time for the excitation according to the actual magnitude of the armature current when the synchronous machine is connected to the load. A limit start timing automatic control means for changing the load is provided. In the overload limiting device for a synchronous machine according to the invention of claim 4, the overload allowable time of the armature winding is set in accordance with the actual magnitude of the armature current when the synchronous machine is not connected to a load. Automatic control means for automatic start of no-load limit start timing, and overload of the armature winding according to the actual magnitude of the armature current when the synchronous machine is connected to the load. A limit start timing automatic control means for load is provided for automatically changing the allowable time. An overload limiting device for a synchronous machine according to a fifth aspect of the present invention is the overload limiting device for a synchronous machine according to the third aspect of the invention, wherein automatic limit start timing control means for no load and limit start for load are provided. The switching means is provided to selectively switch the automatic timing control means. An overload limiting device for a synchronous machine according to a sixth aspect of the present invention is the overload limiting device for a synchronous machine according to the fourth aspect of the invention, wherein the automatic limit start timing control means for no load and the limit start for load are provided. The switching means is provided to selectively switch the automatic timing control means.

In the overload limiting device for a synchronous machine according to the seventh aspect of the present invention, the excitation limitation starts later when the actual armature current is smaller than when the actual armature current is large. . In the overload limiting device for a synchronous machine according to the invention of claim 8, the overload allowable time of the armature winding is longer when the actual armature current is smaller than when the actual armature current is large. Of.

In the overload limiting device for a synchronous machine according to the ninth aspect of the present invention, (I ² -1) [where I is an actual armature] when the automatic limiting start timing control means starts the excitation limitation. P. current to rated armature current. U. Value] of the integrated predicted value (I ² −1) t [however, according to the magnitude of the armature current]
[t is time] is set in advance, and the restriction start timing of the excitation is calculated based on the integrated predicted value (I ² −1) t corresponding to the magnitude of the actual armature current detected by the detection means. It changes automatically. In the overload limiting device for a synchronous machine according to the invention of claim 10, in the case (I ² -1) in the case where the automatic limiting start timing control means starts the overload limiting,
Integrated predicted value (I ² −1) t according to the magnitude of armature current
Is set in advance, and the integrated predicted value (I ² corresponding to the magnitude of the actual armature current detected by the detection means is calculated.
-1) The allowable overload time of the armature winding is automatically changed based on t. In the overload limiter for a synchronous machine according to the invention of claim 11, the limit start timing automatic control means comprises:
The integrated predicted value (I ² -1) t of (I ² -1) when the excitation limitation is started is predictively calculated, and the integrated predicted value ((I ² -1)) corresponding to the magnitude of the actual armature current detected by the detection means ( Based on I ² -1) t, the excitation start timing of the excitation is automatically changed. Overload limiting device of a synchronous machine according to the invention of claim 12, the limit start timing automatic control means, the integrated predicted value in the case of starting the overload limit (I ² -1) to (I ² -1) t The allowable overload time of the armature winding is automatically changed on the basis of the integrated predicted value (I ² −1) t corresponding to the magnitude of the actual armature current detected by the detection means. It is a thing.

According to the thirteenth aspect of the present invention, in the overload limiting device for a synchronous machine, the automatic limit start timing control means starts the excitation limit.

[0019]

[Equation 1]

Prediction calculation is performed, and the excitation limitation start time is automatically changed based on the calculated value. In the overload limiting device for a synchronous machine according to the fourteenth aspect of the present invention, the limit start timing automatic control means is provided when the overload limiting is started.

[0021]

[Equation 1]

By predicting and calculating, the allowable overload time of the armature winding is automatically changed based on the calculated value.

In the overload limiter for a synchronous machine according to the fifteenth aspect of the present invention, the automatic limit start timing control means predictively calculates K (I + 3) (I-1) when the excitation limit is started, and this calculation is performed. Based on the value, the start time of the excitation limitation is automatically changed. In the overload limiting device for a synchronous machine according to the sixteenth aspect of the present invention, the automatic limit start timing control means predictively calculates K (I + 3) (I-1) when the overload limit is started, and the calculated value is set to this calculated value. Based on this, the allowable overload time of the armature winding is automatically changed.

[0024]

In the overload limiting device for a synchronous machine according to the first aspect of the present invention, the limiting start timing automatic control means automatically changes the limiting start timing of the excitation according to the magnitude of the actual armature current. , The armature current can exceed the rated armature current and flow near the withstand limit of the armature winding, and the synchronous machine can supply more electric power. Claim 2
In the overload limiting device for a synchronous machine according to the invention, the limit start timing automatic control means automatically changes the overload allowable time of the armature winding according to the magnitude of the actual armature current. The current can flow beyond the rated armature current to near the withstand limit of the armature winding, and the synchronous machine can supply more electric power.

In the overload limiting device for a synchronous machine according to the third and fifth aspects of the present invention, when the synchronous machine is in a no-load operation, the automatic starting means for controlling the start time of the no-load operation causes the actual electric machine in a no-load state. The excitation limit start timing automatically changes according to the magnitude of the armature current, and during load operation, the limit start timing automatic control means for no load changes the actual armature current magnitude at no load. In response to each operation, the armature current exceeds the rated armature current, and the armature current further exceeds the rated armature current regardless of the no-load operation or the load operation. It is possible to flow near the withstand limit of the winding, and the synchronous machine can supply more electric power.
In the overload limiting device for a synchronous machine according to the invention of claims 4 and 6, when the synchronous machine is under no-load operation, the limit start timing automatic control means for no-load controls the actual armature current during no-load. The allowable overload time of the armature winding automatically changes according to the size, and during load operation, the automatic start control means for the no-load limit start time adjusts the actual armature current at no load. Therefore, the allowable overload time of the armature winding changes automatically, and it is suitable for each operation, no load operation and load operation, and the armature current exceeds the rated armature current. Further, the armature winding can be made to flow near the withstand limit, and the synchronous machine can supply more electric power.

In the overload limiting device for a synchronous machine according to the seventh aspect of the present invention, the limit start timing automatic control means
Excitation limit starts later when the actual armature current is smaller than when the actual armature current is large, and the armature current exceeds the rated armature current and is near the withstand limit of the armature winding. The synchronous machine can supply more electric power. In the overload limiting device for a synchronous machine according to the invention of claim 8, the armature is smaller when the actual armature current is smaller than when the actual armature current is large by the automatic limitation start timing control means. The winding overload permissible time becomes longer, the armature current can flow beyond the rated armature current to near the withstand limit of the armature winding, and the synchronous machine can supply more electric power.

In the overload limiting device for a synchronous machine according to the invention of claim 9, (I ² −
1) the integrated predicted value (I ² according to the magnitude of the armature current)
-1) Based on the integrated predicted value (I ² -1) t, the limiting start timing automatic control means in which a plurality of t are set in advance determines the limiting start timing of the excitation to the actual magnitude of the armature current. Correspondingly, it changes automatically and the armature current can exceed the rated armature current and flow closer to the endurance limit of the armature winding, and the synchronous machine can supply more power.
In the overload limiting device for a synchronous machine according to the invention of claim 10, the integrated predicted value (I ² -1) corresponding to the magnitude of the armature current when (I ² -1) when overload limiting is started. ) Based on the integrated predicted value (I ² -1) t, the limit start timing automatic control means in which a plurality of t are set in advance determines the overload allowable time of the armature winding based on the actual armature current. Correspondingly, it changes automatically, and the armature current can flow beyond the rated armature current to the vicinity of the withstand limit of the armature winding, and the synchronous machine can supply more electric power.

In the overload limiter for a synchronous machine according to the invention of claim 11, the limit start timing automatic control means is provided.
The integrated predicted value (I ² -1) t of (I ² -1) when the excitation limitation is started is predicted and calculated, and the integrated predicted value (I ^2-
1) Based on t, the excitation start timing is automatically changed according to the magnitude of the actual armature current, and the armature current exceeds the rated armature current and the withstand capacity of the armature winding is further exceeded. It can flow near the limit and the synchronous machine can supply more power. In overload limiting device of a synchronous machine according to the invention of claim 12, the restriction start timing automatic control means, the integrated predicted value of (I ² -1) in the case of starting the overload limit (I ² -1) t Is calculated, and the allowable overload time of the armature winding automatically changes according to the magnitude of the actual armature current based on the integrated predicted value (I ² −1) t. Can flow beyond the rated armature current to near the withstand limit of the armature winding, and the synchronous machine can supply more electric power.

In the overload limiter for a synchronous machine according to the thirteenth aspect of the present invention, the limit start timing automatic control means is used.
When starting the excitation limitation

[0030]

[Equation 1]

Is predicted and calculated, and based on this calculated value,
The excitation start time limit automatically changes according to the magnitude of the actual armature current, and the armature current can flow beyond the rated armature current and near the withstand limit of the armature winding. , Synchronous machines can supply more power. In the overload limiting device for a synchronous machine according to the invention of claim 14, when the overload limiting is started by the automatic start control means for limiting time.

[0032]

[Equation 1]

Is predicted and calculated, and based on the calculated value,
The allowable overload time of the armature winding automatically changes according to the magnitude of the actual armature current. Can flow and the synchronous machine can supply more power.

In the overload limiter for a synchronous machine according to the fifteenth aspect of the present invention, the limit start timing automatic control means allows
K (I + 3) (I-1) when the excitation limitation is started is predicted and calculated, and based on this calculated value, the excitation limitation start time is automatically determined according to the magnitude of the actual armature current. On the contrary, the armature current can flow beyond the rated armature current to the vicinity of the withstand limit of the armature winding, and the synchronous machine can supply more electric power. In the overload limiter for a synchronous machine according to the sixteenth aspect of the present invention, the K when the overload limit is started by the limit start timing automatic control means.
(I + 3) (I-1) is predictively calculated, and the allowable overload time of the armature winding is automatically changed according to the magnitude of the actual armature current based on the calculated value. Is
It is possible to flow beyond the rated armature current to the vicinity of the endurance limit of the armature winding, and the synchronous machine can supply more electric power.

[0035]

【Example】

Example 1. 1 to 7 are views for explaining a first embodiment of the present invention, FIG. 1 is a connection diagram showing the configuration of the entire apparatus, and FIG.
Is a connection diagram showing the detailed configuration of the (I ² -1) integrating device, FIG. 3 is a connection diagram showing the detailed configuration of the (I ² -1) t predicting device, and FIG. Diagrams showing respective relationships among reactive power, field control, rated armature current, and actual armature current, FIGS. 5 and 6 are respectively a rated armature current, actual armature current, and field weakening control start, Each relationship of the above, the overload limit start time (field weakening control start time)
Is a diagram showing a case of different values, FIG. 7 is a diagram showing the relationship between the rated armature current, the actual armature current, and the start of field weakening control, and the withstand capacity of the armature windings. The time when the armature current exceeds the rated armature current is shown as the 0 point on the time axis.

First, the structure of the first embodiment will be described in detail below. In FIG. 1, reference numeral 5 is a detection means for detecting the actual armature current I _AR of the synchronous machine 1, which is, for example, a CT (current transformer for instrument). Reference numeral 13 is a relay, which is a polarity switcher 11 and AVR.
The connection with the (automatic voltage regulator) 4 is turned on / off, that is, the overload limiting signal supplied from the polarity switcher 11 to the AVR 4 is turned on / off. Reference numeral 14 denotes an integrating device which receives the output of the AC / DC converter 6, and outputs the integrated value (I ² -1) t of (I ² -1) as its output 14s. Incidentally, I is the actual armature current I input from the AC / DC converter 6.
_AR of _P.V. for rated armature current I _AT . U. (Per unit) value, the armature current I _AR when the synchronous machine 1 is operated in the rated state is 1 P.s. U, when the actual armature current I _AR input from the AC / DC converter 6 is twice the rated armature current I _AT , the actual armature current I _AR is 2
P. U. t is time. Reference numeral 15 is a predicting device which receives the output of the AC / DC converter 6, and outputs (s) (I ² −1) t after the armature current limit of the synchronous machine 1 is started, that is, after the overload limit is started, as its output 15 s. The predicted value of is output.

Reference numeral 16 is an adder, and its output 16s is
The output 14s of the integration device 14 and the output 15s of the prediction device 15 are added and output. 17 is (I
² -1) at t operation setter, the armature of the synchronous machine 1 current I
_The (I ² -1) t value that starts the restriction of _AR is set, and the set value can be set arbitrarily, but after the setting, the output 17s is constant and does not change. In the embodiment, the set value is 40. Reference numeral 18 denotes a comparator, which outputs the output of the adder 16 and the (I ² -1) t operation setting unit 1
The output of the adder 16 is compared with the output of (I
The larger the output of the ² -1) t operation setter 17, biasing the relay 13, is intended to pre-fill operation to the relay 13. Reference numeral 19 is a limit start timing automatic control means,
The actual armature current I detected by the detection means 5
_This is for automatically changing the excitation start limit time of the synchronous machine 1, that is, the overload limit start time of the synchronous machine 1, depending on the size of _AR.
4, a prediction device 15, an adder 16, an (I ² −1) t operation setting device 17, and a comparator 18. Reference numeral 20 is a circuit breaker for inserting the synchronous machine 1 into the electric power system 12 at the predetermined time point after the synchronous machine 1 is activated, for example, and connects the synchronous machine 1 to the electric power system 12. In addition,
Reference numerals 1, 2, 3, 4, 6, 7, 7, 8, 9, 10, 11, 1
2 has the same or equivalent function as in the case of FIG. 10 described above, and therefore description thereof will be omitted.

FIG. 2 is a diagram showing the detailed internal structure of the (I ² -1) accumulator 14, in which FIG. 2 shows a divider 14 _{1 which} is the actual armature current from the AC / DC converter 6. I
_AR and the rated armature current I _AT set in the rated armature current setting device 14 ₂ are input to obtain the actual armature current I _AR.
P. It outputs a U value, that is, I. 14 ₃ is a multiplier, which inputs the output I of the divider 14 ₁ and outputs I ₂ . 14 ₄ 1 setter, the (I ² -1)
1 is set. 14 ₅ is an integrator, which receives the output I ₂ of the multiplier 14 _{3 and} the output 1 of the 1-setting device 14 ₄ and obtains (I ² -1) from these two inputs at its input stage. (I ² −1) is integrated to obtain (I ² −
1) t is output, and the output (I ² −1) t is the same as the above (I ² −
1) The output 14 s of the accumulator 14 becomes the adder 16
Is one of the inputs. r is a resistance.

FIG. 3 is a diagram showing the detailed internal structure of the (I ² -1) t predicting device 15. In FIG. 3, 15 _1a is the first comparator and the first armature current setting. Bowl 15
1 _aa , a first amplifier 15 _1ab , a first semiconductor switching element 15 _1ac, and a resistor r, and the first amplifier 15 _1ab includes the first armature. Current setter 15 _1aa set value output and the above
The deviation from the output of the direct converter 6, ie the actual armature current I _AR , is supplied. 15 _1j is the j-th comparator, which is the j-th armature current setting device 15 _1ja and the j-th amplifier 1.
5 _1jb and the j-th semiconductor switching element 15
_1jc and a resistor r, and the j-th amplifier 15 _1jb includes the j-th armature current setting device 1
The _deviation between the set value output of 5 _{1ja and} the output of the _AC / _DC converter 6, that is, the actual armature current I _AR is supplied. The j-th armature current setter 15 _1ja has a larger set value than the first armature current setter 15 _1aa .

[0040] 15 _2a in the first relay is energized by the conduction of the first-th semiconductor switching element 15 _1ac in the 1st comparator 15 _1a, it is intended to close the a-contact 15 _2aa . 15 _2j in the j-th relay is energized by the conduction of the j-th said in the comparator 15 _1j of the first semiconductor switching element 15 _1Jc, those close that a contact 15 _2Ja.

15 _3a is the first (I ² -1) t prediction setter, 15 _3j is the jth (I ² -1) t prediction setter,
15 ₄ is an adder, each output of the first (I ² −1) t prediction setting unit 15 _3a to the j-th (I ² −1) t prediction setting unit 15 _3j is the first output. th relay 15 _2a ~ the j-th relay 15 is supplied through the respective a-contact 15 _2aa to 15 _2Ja of _2j, and outputs these supplied each output as an addition to the output 15s. Also, this adder 15 ₄
Is composed of an operational amplifier _154a that adds and amplifies the respective supplied outputs, and a resistor r.

In FIG. 4, P on the horizontal axis is active power, Q on the vertical axis is reactive power, P ₁ is active power supplied to the power system 12 by the synchronous machine 1, and Q ₁₁ , Q ₂ and Q ₃ are Reactive power that the synchronous machine 1 is supplying to the power system 12 and Q ₁₁ is the power system 12
The invalid if power requirements are small from the case Q ₂ is the Q ₁₁ is greater than demand for reactive power from the power system 12, Q ₃ is the demand for reactive power from the utility grid 12 Q ₂
The larger cases are shown. I _AR11 is the actual armature current of the synchronous machine 1 when the synchronous machine 1 is supplying the active power P ₁ and the reactive power Q ₁₁ to the power system 12, and I _AR2 is the active power of the synchronous machine 1 to the power system 12 P ₁ is the actual armature current of the synchronous machine 1 when supplying the reactive power Q ₂ , I _AR3 is when the synchronous machine 1 supplies the active power P ₁ and the reactive power Q ₃ to the power system 12. The actual armature current of the synchronous machine 1, I _AT, is the rated armature current curve of the synchronous machine 1. I _AL is a limit allowable current of the actual armature current of the synchronous machine 1, and is a limit at which the actual armature current can flow without lowering the insulation of the armature winding.

In FIGS. 5 to 7, t on the horizontal axis represents time, I _{A on} the vertical axis represents armature current of the synchronous machine 1, I _AR11 , I _AR2 , I.
_AR3 and I _AT are the I _AR11 , I _AR2 , and I _AR2 shown in FIG.
The same armature current as I _AR3 and I _AT , t ₁ is the time when the actual armature current starts to change from I _AR11 to I _AR2 , and t ₂ is the actual armature current I _{AR2 which} is the rated armature current I _AT . It is the time when the accumulator 14 starts to output an output when it exceeds. t ₄₂
Is a time point at which the prediction device 15 starts to output an output, t ₅₂ is a time point at which the excitation limit of the synchronous machine 1 is started (start of overload limit), 14 s is the output of the (I ² −1) integrating device 14, and 15 s is (I ² −1). )
t predictor 15 output, 16s is adder 16 output, 1
7s is the output of the (I ² -1) t operation setting unit 17. In FIG. 7, A _TL is an endurance curve of the armature winding, and shows a limit value at which the armature winding starts to cause an abnormality such as insulation deterioration in a relation between the armature current I _A and time t. .

Next, the operation of the first embodiment will be described. First, the operation of the entire apparatus will be described with reference to FIG. 1 showing the configuration of the entire apparatus with reference to FIGS. In FIG. 1, an AC / DC converter 6, an armature current limit start value setter 7,
The relative series of operations of the adder 8, the amplifier 9, the power factor detector 10, and the polarity switcher 11 are basically the same as the above-mentioned operations shown in FIG.
The description is omitted, and other parts will be mainly described.

First, when the synchronous machine 1 is operated in the rated state, the relay 13 is not energized and its contact 1
3a is open, and the output of the polarity switch 11 is not supplied to AVR4. Therefore, until the relay 13 is energized and its contact 13a is closed, the output of the AC / DC converter 6, that is, the actual armature current I _AR , is less than the set value of the armature current limit start value setter 7. Even if it becomes large, the excitation limitation of the synchronous machine 1 by the AVR 4, that is, the overload limitation is not performed.

Here, the actual armature current I _AR output from the AC / DC converter 6 is shown by I _AR2 and I _AR3 in FIGS. 5 and 6 in _response to the request for the reactive power from the power system 12. the larger than the rated armature current I _aT to, P. of the armature current I _AR2, I _AR3 when said actual U value and time t
Course of, depending on the integrated value (I ² -1) t of (I ² -1) multiplication unit 14 whose output 14s, i.e. (I ² -1),
Output to the adder 16. This output 14s is shown in FIG. 5 and FIG.
It changes as shown in. On the other hand, the (I ² −1) t predicting device 15 is subjected to excitation limitation (overload limitation) at that time according to the magnitude of the actual armature current I _AR output from the AC / DC converter 6. In the case of (I
² −1) The predicted value of t is output as 15 s, and the adder 1
Supply to 6. This output 15s has a relatively small actual armature current I _AR that exceeds the rated armature current I _AT.
In the case of _AR2 , it occurs at time t ₄₂ as shown in FIG. 5, and in the case of I _{AR3 in which} the _actual armature current I _AR is relatively large,
As shown in FIG. 6, it occurs at time t ₄₃ and increases with the passage of time. The adder 16 supplies an output 16s obtained by adding the output 14s of the accumulator 14 and the output 15s of the predictor 15 to the comparator 18. This output 16s changes as shown in FIGS. In the comparator 18, the output 16s of the adder 16, that is, the sum of the output 14s of the accumulator 14 and the output 15s of the predictor 15 is the set value 4 of the (I ² −1) t setter 17.
0, that is, output 17 s, the relay 13 is not energized if smaller, and the relay 13 is energized when the set value 40 is reached.

When the relay 13 is energized, its contact 13
Since a is closed, the deviation detector 8 at the time of closing
Of the AC / DC converter 6, that is, the difference between the output of the AC / DC converter 6 (actual armature current I _AR ) and the set value of the armature current limit start value setter 7, the excitation limit (overload The (limit) signal is supplied from the polarity switcher 11 to the AVR 4. In this case, since it is in the state of the delay phase in which the reactive power is requested from the electric power system 12, the polarity switching device 11 supplies the output of the polarity for performing the field weakening control to the AVR 4. AVR4 is
Starting the field weakening control according to the magnitude of the deviation signal from the polarity switcher 11, the actual armature current I of the synchronous machine 1 is started.
_In the case of relatively small I _AR2 , as shown in FIG. 5, the _AR starts to decrease from the time point t _{52 of the} field weakening control start, and in the case of relatively large I _AR3 , the field weakening control starts as shown in FIG. _Starts to decrease from time t ₅₃ , and in either case,
Limited to fall within the rated armature current I _AT . When the actual armature current I _AR3 is limited to fall within the rated armature current I _AT by the field weakening control (overload limitation) as described above, the reactive power supplied to the power system is indicated by an arrow in FIG. As shown in, it decreases as Q ₃ → Q ₂ → Q ₁₁ .

[0048] Incidentally, since the multiplication unit 14 outputs an integrated value (I ² -1) t of as described above (I ² -1), the P. actual armature current I _AR If the U value I is small,
Although the value of (I ² -1) is small, if t becomes large, that is, if a long time elapses, the comparator for inputting the added value of the output 14s of the accumulator 14 and the output 15s of the predictor 15 is input. 18 outputs. On the contrary, the actual armature current I _AR of P. If the U value I is large,
Since the value of (I ² −1) becomes large, even if t is small,
That is, the comparator 18 outputs an output in a short time. That is, even if the actual armature current I _AR exceeds the rated armature current I _AT and the magnitude thereof is relatively small (for example, I _AR2 in FIGS. 4, 5, and 7), the relay contact 13a is closed relatively slowly, thus, excitation limit of the synchronous machine 1 (overload limit) is 5, beginning slowly as shown by the restriction start time t ₅₂ in FIG. 7, on the contrary, its size is relatively When it is larger (for example, I _AR3 in FIGS. 4, 6 and 7), the relay contact 13 is used.
a closes relatively early, and therefore excitation limit (overload limit)
Starts earlier as shown by the restriction start time t ₅₃ in FIGS. 6 and 7. By this operation, as shown by I _AR2 and I _AR3 in FIG. 7, the actual armature current I _AR does not exceed the rated armature current I _AT and further does not exceed the withstand curve A _TL of the armature winding. It can flow up to the vicinity of the withstand curve A _TL of the armature winding. That is, while reliably protecting the armature winding from its insulation deterioration, and by positively and fully utilizing the armature winding margin area B (the hatched portion), reactive power is supplied to the power system 12. Supply more (eg Q ₃ in Figure 4),
The power system can be made more stable.

By the way, the withstand capacity of the armature winding of the synchronous machine 1 is slightly different due to the difference in the structure of the synchronous machine 1 and the difference in capacity, but it can be expressed by the formula (1). t = 40 / (I ² −1) ………………………………………… (1) However, I is the actual value when the synchronous machine 1 is operating in the rated state. Armature current 1P. U. The actual armature current P. U. It is a value. Therefore, in order to protect the insulation resistance of the armature winding of the synchronous machine 1 from decreasing, (I
Before the accumulated value of ^{2 -1) (I 2 -1)} t is 40, and the field-weakening control the synchronous machine 1 is excited limit (overload limit), the actual armature current I _AR (FIGS. 4-7 I _AR2 and I _{AR3 in}
Should be limited to the rated armature current I _AT (1 P.U.) or less. However, the integrated value of (I ² −1) (I ² −
1) If the limiting operation is started immediately before t reaches 40, the actual armature current I _AR instantly changes to the rated armature current I _AR.
Speaking of being limited to _AT (1 P.U.) or less, that is not the case. In reality, due to the field time constant of the synchronous machine 1, the actual armature current I _AR is instantaneously changed to the rated armature current I _{AR. Does} not decay below _AT . The degree of this attenuation is different in the case and if the actual armature current I _AR is large or small, who when the actual armature current I _AR is large, than small time to decay Takes.

Therefore, it is necessary to start the limit in anticipation of (I ² -1) to be integrated even after the start of the excitation limit (overload limit) by the field time constant. The armature depends on the field time constant and (I ² −1) t between the time when the child current I _AR exceeds the rated armature current I _AT and the time when the limit (overload limit) is started. In order that the sum of (I ² −1) t in the period from the start of the current limit until the current I _AR reaches the rated armature current I _AT does not exceed 40, the limit start time is set to the actual value. It may be changed according to the magnitude of the armature current I _AR . In order to make such a change, as shown in FIG.
² -1) multiplication unit 14, and, taking into account the decay time that depends on the field磁時constant the limiting after the start (I ² -
1) By providing the t prediction device 15, it is predicted that the actual armature current I _AR exceeding the rated armature current I _AT is relatively small and the integrated value of (I ² −1) t after the start of the restriction is small. In this case, the overload condition is allowed for a long time to contribute to the improvement of the power system stability, and the actual armature current I _AR exceeding the rated armature current I _AT is large (I ² after the start of the limitation). −
1) When it is predicted that the integrated value of t is large, it is sufficient to quickly perform the above-mentioned restriction to protect the armature winding of the synchronous machine 1 from insulation deterioration.

Next, with reference to FIGS. 2 and 3, FIG. 5 and FIG. 6 will be referred to for concrete operations of the (I ² −1) accumulator 14 and the (I ² −1) t predictor 15 described above. While explaining. First, FIG. 2, with reference to FIGS. 5 and 6, according to (I ² -1) multiplication unit 14 (I ² -1) t
The operation of obtaining When the actual armature current I _AR from the AC / DC converter 6 and the rated armature current I _AT set in the rated armature current setter 14 ₂ are input to the divider 14 ₁ , the divider 14 in 14 _1, by dividing the actual armature current I _AR at the rated armature current I _aT, the (I ² -1) t
Of the actual armature current I _AR at P. The U value, that is, I is output. The output I of this divider 14 ₁ is the multiplier 1 of the next stage.
When input to 4 ₃ , the multiplier 14 ₃ outputs the I to 2
And multiply, wherein the (I ² -1) derives the I ² at t output. On the other hand, since the 1-setting device 14 ₄ outputs 1 in (I ² -1) t, the output 1 of the 1-setting device 14 ₄ and the output I ² of the multiplier I 14 ₃ are the integrators of the next stage. 14 ₅ which is fed to these integrators 14 ₅ from these two inputs I ² and 1 at its input stage (I ² −1) and this (I ² −1)
Is integrated to output (I ² -1) t. This integrator 14 ₅
Output (I ² −1) t of the above becomes the output 14 s of the (I ² −1) accumulator 14 and becomes one input of the adder 16. As shown in FIGS. 5 and 6, the integrator 14
₅ , that is, the integrator 14 has a greater value (eg, I _{AR3 in} FIG. 6) when the actual armature current I _AR from the AC / DC converter 6 is smaller (eg, I _{AR2 in} FIG. 5), That is, the actual armature current I _AR P.I. A large output 14s is generated earlier when the U value I is larger than when it is small.

Next, referring to FIG. 5 and FIG. 6, the operation of obtaining (I ² −1) t after the start of restriction by the (I ² −1) t predicting device 15 will be described with reference to FIG. First, the reactive power required from the power system is not so large, and the actual armature current I _AR output from the AC / DC converter 6 is not.
Is larger than the set value of the first armature current setter 15 _1aa but exceeds the rated armature current I _AT , but is larger than the set values of the other armature current _setters 15 _1ja . The case of I _AR2 in FIGS. 4 and 5 will be described as an example of the case of being smaller. If the actual armature current I _AR is larger than the set value of the first armature current setter 15 _1aa and smaller than the set values of the other armature current _setters ... 15 _1ja , the first semiconductor Only the switching element 15 _1ac conducts, only the first relay 15 _2a is energized, and only its a contact 15 _2aa closes. Since only the a-contact 15 _2aa is closed, the first predicted setting value (I ² -1) t (I ² -1) t of the (I ² -1) t prediction setter 15 _3a [however, the decay time depending on the field time constant is Only a fixed value arbitrarily set in consideration of the above] is output from the adder 15 ₄ to the output 15 of the (I ² −1) t prediction device 15 after the limitation is started.
As s, it is output as indicated by 15s in FIG. 5, and becomes the other input of the adder 16.

Next, the reactive power required from the power system is large, and the actual armature current I _AR output from the AC / DC converter 6 greatly exceeds the rated armature current I _AT and the armature. A case in which the value is larger than the set value of the current setter 15 _1ja will be described. Actual armature current I _AR is larger than the set value of the armature current setter 15 _1ja all of the first semiconductor switching element 15 _1ac ~ j th semiconductor switching element 15 _1Jc conducts, the all of the first relay 15 _2a ~ j-th relay 15 _2j is energized, all of them a contact 15 _2aa to 15 _2Ja closes. Because all of a contact _{15 2aa} ~15 2ja is closed, the first
Th (I ² -1) t prediction setter 15 _3a ~ j th (I ² -1) t prediction setter 15 each prediction set value of _3j (I ²
-1) t (however, any set value is a fixed value preset in consideration of the decay time depending on the field time constant) is added by the adder 15 ₄ , and this added value is added Bowl 1
5 _4, the limit after starting of the (I ² -1) t predictor 15
6 is output as the output 15s of FIG. 6 (however, FIG. 6 shows the case where the respective set values of the three armature current setting devices are added), and the adder 16
The other input of. Thus, the reactive power required from the power system is not so large and the AC / DC converter 6
As compared with a case where the actual armature current I _AR output from the I _AR exceeds the rated armature current I _AT but is relatively small, the reactive power required from the power system is large.
When the actual armature current I _AR output from the direct converter 6 greatly exceeds the rated armature current I _AT , the output of the (I ² −1) t predicting device 15 after the start of the limitation. 15
s is large and comes out quickly.

Therefore, the sum of the output 14s of the (I ² -1) integrating device 14 and the predicted value output 15s after the start of the limitation by the (I ² -1) t predicting device 15, that is, the comparator 18 The output 16s of the adder 16 supplied as one of the inputs is also not so large in reactive power required by the power system, and the actual armature current I _AR output from the AC / DC converter 6 is relatively small. Compared with the case, when the reactive power required from the power system is large and the actual armature current I _AR output from the AC / DC converter 6 is large,
It is big and comes out quickly. The other input of the comparator 18 is the set value 40 (fixed value) of the (I ² −1) t operation setter 17
When the output 16s of the adder 16, which is the one input of the comparator 18, reaches the set value 40 (fixed value), the comparator 18 outputs an output.
As described in the explanation of the operation of 1., the relay 1 for starting the restriction
3 is energized, the a-contact 13a (FIG. 1) is closed, and the excitation of the synchronous machine 1, that is, the overload is limited.

In FIG. 3, the numbers of the (I ² -1) t prediction _setters 15 _3a to 15 _3j and the relays 15 _2a to 15 _2j may be determined according to the required accuracy, but it goes without saying that The more you increase the accuracy, the better.

Example 2. In the first embodiment shown in FIGS. 1 to 3, as described above, the first to the Jth (I ² −1) t.
Although the example of sequentially adding (logical product) the outputs of the prediction _setters 15 _3a to 15 _3j has been shown, they are sequentially switched (the logical sum is taken).
Even if it does so, the same effect can be obtained. Of course, in order to make an appropriate prediction setting, in the case of sequential switching (logical sum), compared to the case of sequential addition (logical product), the _subsequent stage of the (I ² −1) t prediction _setters 15 _3a to 15 _3j The set value may be increased. Further, in the first embodiment shown in FIGS. 1 to 3, the relays 13 and 15 _2a to 15 _2j are shown to have contact points as an example, but they can also be realized by using a semiconductor such as a transistor.

Example 3. Example 1 shown in FIGS. 1 to 3 is
Predictive setter 1 preset according to the actual armature current value
Although 5 _3a is an example for switching to 15 _3j, 8 directly from the actual armature current, automatically, limit after the start of the (I ² -
1) An example of an (I ² -1) t automatic prediction device 15 that calculates a predicted value of t. The parts other than those shown in FIG. 8 have the same configuration and operation as those of FIG. The automatic prediction device 1 shown in FIG.
5 is the prediction calculation formula (2) of (I ² -1) t after the start of restriction.
FIG. 6 shows an example of realizing the expression (3) in which the above is simplified.

[0058]

[Equation 2]

However, t1 indicates the time required from the start of the limit to the return to the allowable current value. I is the actual armature current when the synchronous machine 1 is operating in the rated state, which is 1P.
U. The actual armature current P. U. It is a value. Simple predicted value = K (I + 3) (I-1) (3) where K is a coefficient determined by the time constant at which the armature current value changes.

In FIG. 8, reference numeral 15 ₅ denotes a rated armature current setting means for setting the rated armature current I _TL .
15 ₆ is a dividing means, which is the actual armature current I _AR , I _AR2 , I
_AR3 is divided by the output I _TL of the rated armature current setting means 15 ₅ to obtain the actual armature current P.P. U value I is calculated, and I
Is output. Numeral 15 ₇ is a first numerical value setting means for setting “3” of (I + 3) in the equation (3). Reference numeral 15 ₈ denotes a first adding means, which adds the output I of the dividing means 15 ₆ and the output “3” of the first numerical value setting means 15 ₇ to obtain (I + 3) in the equation (3), This (I + 3) is amplified by its own amplification means _158a and output. 15 ₉ is the second numerical value setting means,
"1" of (I-1) in the equation (3) is set. 15 ₁₀ is a second adding means, which is the dividing means 1
5 wherein the ₆ output I of the second output "1" of the numerical value setting means 15 ₉ and the adds the seek (3) (I-1) in the formula, its amplification means the (I-1) It is amplified by 15 _10a and output. 15 ₁₁ In the first multiplying means, at the output of the first addition means 15 ₈ (I + 3) and the output of the second addition means 15 ₁₀ (I-1) and multiplying by the formula (3) (I + 3) (I-1) is obtained, and the (I
+3) (I-1) is output. 15 ₁₂ by the coefficient setting means is for setting the coefficient K in the equation (3). 15 ₁₃ the second multiplication means, the first output of the multiplying means 15 ₁₁ (I + 3) (I-1) and the coefficient setting means 15 the by multiplying the output K of ₁₂ (3) K ( I +
3) (I-1), that is, a simple predicted value is obtained.
15 ₁₄ in the amplifying means, the K (I at the amplifying unit 15 _14a
+3) (I-1) is amplified and output 1 of the automatic prediction device 15
It is output as 5s. Each addition means 1
R in 5 ₈ , 15 ₁₀ and amplifying means 15 ₁₄ is a resistance.

In the automatic predicting device 15, the K (I + 3) (I-1) automatically calculated from the actual armature currents I _AR , I _AR2 and I _AR3 is one of the adders 16 Of the (I ² −1) accumulator 14 ((I ² − in FIG. 2) to the other input of the adder 16.
1) The output (I ² -1) t of the same configuration and the same function as the accumulator 14 is supplied. The comparator 18 outputs the output K (I + 3) (I−1) of the automatic predicting device 15 and the (I
² −1) The sum of the output (I ² −1) t of the output accumulator 14 is supplied from the adder 16, and thereafter, the same operation as that of the above-described first embodiment is performed, and the same effect as that of the first embodiment is obtained. Play. In addition, according to the automatic predicting device 15 of the third embodiment, as in the first embodiment described above, a plurality of predictive value setting devices 15 _3a to 1 _3a- 1.
5 _3j , the comparators 15 _1a to 15 _1j , and the relays 15 _2a to 15 _2j are unnecessary, and the configuration of the device is simpler and smaller than that of the first embodiment.

Example 4. In the above-described third embodiment, the example using the simplified formula (3) is shown, but the formula (2) may be circuitized or used as it is, or an approximate formula of these formulas may be circuitized or used. Even if it does, the same effect as the above-mentioned Example 1 is produced.

Example 5. In the first embodiment, an example in which the predictive _setters 15 _3a to 15 _3j are simply switched according to the magnitude of the armature current has been described. However, when the synchronous machine 1 is connected to the grid and when there is no load. The armature current changes differently depending on the time, and (I
² -1) the accumulated value of t also different. Therefore, the embodiment shown in FIG. 9, the synchronous machine 1 when connected to the grid (I ² -1) under load adapted to t and (I ² -1) t prediction device 15A, the no-load and (I ² -1) no load adapted to t (I ² -1) t prediction apparatus 15B of the case, operates when the synchronous machine is connected to the system, for example, connect the synchronous machine 1 on line 12 And a relay 21 that operates when the a-contact 20a of the circuit breaker 20 is closed. The relay 21 is closed by closing the a-contact 20a when the circuit breaker 20 is closed.
The a-contact 21a of is closed and the b-contact 21b is opened,
The load (I ² -1) t predicting device 15A automatically
It is connected between the AC / DC converter 6 and the adder 16, and the unloaded (I ² -1) t predicting device 15B is automatically disconnected. When the circuit breaker 20 opens and the synchronous machine 1 becomes unloaded, the a contact 20a of the circuit breaker 20 opens so that the relay 2
1 a contact 21a opens and b contact 21b closes,
The unloaded (I ² -1) t predictor 15B is automatically connected between the AC / DC converter 6 and the adder 16, and the unloaded (I ² -1) t predictor is also provided. 15A is automatically separated. Therefore, by using the fifth embodiment shown in FIG. 9, it is possible to cope with both no load and connection to the system.

Example 6. In the above-described fifth embodiment, as shown in FIG. 9, an example in which the entire (I ² −1) t prediction device 15 is provided with one load-use 15A and one no-load-use 15B is provided. Although not shown, ^two (I ² −1) t predicting devices 15 are not placed, and, for example, in FIG. 3 of the first embodiment, the predictive _setters 15 _3a to 15 _3j are _replaced by one set for load, no load. 1 set for use, a total of 2 sets, and automatic switching means (a contact 20a of the circuit breaker 20 in FIG. 9 and a relay are provided in front of the adder 15 ₄ so as to automatically switch between loaded and unloaded. 21,
By providing the relay contact 21 _a and the relay contact 21 _b ), the same effect as in the case of the fifth embodiment shown in FIG. 9 can be obtained. The parts other than those shown in FIG.
Since the configuration and the operation are the same, the illustration and description are omitted.

The change in the field current I _F of the synchronous machine 1 is
Generally, it changes with an open circuit time constant Tdo 'when there is no load, and with a time constant Tg represented by the equation (4) when connected to the system. Tg = (Xd ′ + Xe) · Tdo ′ / (Xd + Xe) (4) where Xd is the reactance of the synchronous machine under no load, Xd ′
Is the reactance of the synchronous machine under no load, and Xe is the reactance of the power system. By limiting the actual armature currents I _AR2 and I _AR3 that exceed the rated armature current I _AT in the synchronous machine,
When returning to the rated armature current I _AT , it is performed by reducing the field current I _F of the synchronous machine as described above. Therefore, the time constant Tdo ′ during no load and the time constant Tg during load are set. difference from limits the rated armature current I actually armature current I _AR2 exceeding the _AT, I _AR3, affects the time to pull back the rated armature current I within the _AT. That is, the (I ² −1) t predicting device 15 that operates after the start of the above-described restriction.
It is necessary to change the predictive set value for the load value and the non-load value.

Regarding the switching according to the operating state of the synchronous machine, two kinds of operation are described, that is, no load and system connection. Further, the number of (I ² -1) t prediction devices 15 is
15A, 15B, 15C, ... By increasing the number of prediction _setters 15 _3a to 15 _3j ,
The number of (I ² −1) t prediction devices 15A, 15B, 15 depending on the system state can be increased by increasing the number of equations.
C, ... Or it can be applied to the case where it is necessary to switch many kinds of prediction setting devices.

Example 7. As described above, the analog circuits have been described in each of the embodiments. However, the same effects as those in the above-described first to sixth embodiments can be realized by software in a control device using a digital circuit or a microprocessor. Play.

Example 8. Further, similarly, in the above-mentioned embodiment, the description is made by applying to the excitation control device having no exciter, but the above-mentioned embodiment is also applied to the excitation control device having a rotary exciter such as a brushless exciter or a DC exciter. It has the same effect as the example. In the above-described embodiment, the predicting device 15 has been shown to operate according to the magnitude of the actual armature current exceeding the rated armature current. Since the magnitude of the armature current can be grasped by the rate of change of the armature current, the prediction device 15
Means that even if it responds to the rate of change of the actual armature current exceeding the rated armature current, it still operates according to the magnitude of the actual armature current exceeding the rated armature current. Is. Further, in each of the above-described embodiments, an overload condition, for example, an overcurrent condition of the armature current that occurs when the power factor of the power system is controlled to be constant, and an armature that occurs when the reactive power of the power system is controlled to be constant. There is also an overcurrent state of the current, and in any case, by applying the present invention, the same effect as each of the above-described embodiments can be obtained. Moreover, in each of the above-described FIGS. 1 to 14, the same reference numerals indicate the same or corresponding portions.

[0069]

According to the invention of claim 1, the limit start timing of the excitation is automatically changed by the limit start timing automatic control means according to the magnitude of the actual armature current. The armature current can be exceeded, and the armature winding can be flown near the withstand limit, and the synchronous machine can supply more electric power. According to the invention of claim 2, the limit start timing automatic control means automatically changes the overload allowable time of the armature winding according to the magnitude of the actual armature current. Therefore, the armature current is the rated armature. Since the current can be passed to the vicinity of the withstand limit of the armature winding, the synchronous machine can supply more electric power.

According to the third and fifth aspects of the present invention, when the synchronous machine is under no-load operation, the excitation start time automatic control means for no-load controls the excitation according to the magnitude of the actual armature current under no-load. Since the limit start time of automatically changes during the load operation, the limit start time for excitation depends on the magnitude of the actual armature current at no load by the automatic limit start time control means for no load. It changes automatically, and whether it is under no-load operation or under load operation is suitable for each operation, and the armature current must exceed the rated armature current and flow to near the withstand limit of the armature winding. And the synchronous machine can supply more power. According to the invention of claims 4 and 6, during no-load operation of the synchronous machine, the limit start timing automatic control means for no-load controls the armature winding according to the magnitude of the actual armature current at no-load. Since the allowable overload time automatically changes, during load operation, the automatic start control function for the no-load limit start timing allows the overload of the armature winding depending on the actual armature current at no load. The permissible time automatically changes, and in both cases of no-load operation and load operation, it is suitable for each operation, the armature current exceeds the rated armature current, and the withstand limit of the armature winding is further exceeded. It can be flown to the vicinity,
Synchronous machines can supply more power.

According to the invention of claim 7, as compared with the case where the actual armature current is large, the automatic start control means for limiting the start time
When the actual armature current is small, the excitation limit starts later, so the armature current can flow beyond the rated armature current to near the withstand limit of the armature winding, and the synchronous machine Can supply more power. According to the invention of claim 8, the limit start timing automatic control means makes the overload allowable time of the armature winding longer when the actual armature current is smaller than when the actual armature current is large. Therefore, the armature current can flow beyond the rated armature current to the vicinity of the withstand limit of the armature winding, and the synchronous machine can supply more electric power.

In the ninth aspect of the invention, a plurality of integrated predicted values (I ² -1) t corresponding to the magnitude of the armature current when (I ² -1) when the excitation limitation is started are set in advance. by the restriction start timing automatic control means, the cumulative estimated value (I ² -1)
On the basis of t, the start time of the limitation of the excitation automatically changes according to the magnitude of the actual armature current, so that the armature current exceeds the rated armature current and the withstand limit of the armature winding is further exceeded. It can flow up to the vicinity, and the synchronous machine can supply more electric power. The invention according to claim 10 is a limit in which a plurality of integrated predicted values (I ² -1) t according to the magnitude of armature current when (I ² -1) when overload limit is started are set in advance. The integrated predicted value (I ²
-1) Based on t, the allowable overload time of the armature winding automatically changes according to the magnitude of the actual armature current.
The armature current can flow beyond the rated armature current to the vicinity of the withstand limit of the armature winding, and the synchronous machine can supply more electric power.

According to the invention of claim 11, (I ² -1) when the excitation restriction is started by the automatic restriction start timing control means.
Of the integrated predicted value (I ² -1) t is calculated, and based on this integrated predicted value (I ² -1) t, the excitation start time is limited according to the magnitude of the actual armature current. Since it changes automatically, the armature current can exceed the rated armature current and flow closer to the endurance limit of the armature winding, and the synchronous machine can supply more electric power. The invention of claim 12, the restriction start timing automatic control means, the integrated predicted value of (I ² -1) in the case of starting the overload limit (I ² -1) t is the prediction calculation, the accumulated prediction value ( Based on I ² −1) t, the allowable overload time of the armature winding automatically changes according to the magnitude of the actual armature current, so the armature current is
It is possible to flow beyond the rated armature current to near the withstand limit of the armature winding, and the synchronous machine can supply more electric power.

According to the thirteenth aspect of the present invention, when the excitation limitation is started by the automatic limitation start timing control means.

[0075]

[Equation 1]

Is predicted and calculated, and based on this calculated value,
Since the excitation start timing of the excitation automatically changes according to the magnitude of the actual armature current, the armature current can exceed the rated armature current and flow near the withstand limit of the armature winding. Yes, the synchronous machine can supply more power.
According to a fourteenth aspect of the present invention, in the case where the overload limitation is started by the limitation start timing automatic control means.

[0077]

[Equation 1]

Is predicted and calculated, and based on this calculated value,
Since the allowable overload time of the armature winding automatically changes according to the magnitude of the actual armature current, the armature current exceeds the rated armature current, and further exceeds the withstand limit of the armature winding. The synchronous machine can supply more electric power.

According to a fifteenth aspect of the present invention, K (I + 3) when the excitation limitation is started by the automatic limitation start timing control means.
(I-1) is predicted and calculated, and based on the calculated value, the excitation start timing is automatically changed according to the magnitude of the actual armature current. Therefore, the armature current is the rated armature. Since the current can be passed to the vicinity of the withstand limit of the armature winding, more power can be supplied to the synchronous machine, and the structure of the device is simple and downsized. According to the sixteenth aspect of the present invention, K (I + 3) (I-1) at the time of starting the overload limitation is predicted and calculated by the automatic limit start timing control means, and based on this calculated value, the armature winding excess Since the allowable load time automatically changes according to the actual armature current, the armature current can exceed the rated armature current and flow closer to the withstand limit of the armature winding. The machine can supply more electric power, and the structure of the device is simple and downsized.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention and is a connection diagram showing an overall configuration of the apparatus.

FIG. 2 is a connection diagram showing a detailed circuit configuration of an (I ² -1) integrating device in Embodiment 1 of the present invention.

FIG. 3 is (I ² −1) t in Example 1 of the present invention.
Connection diagram showing the detailed circuit configuration of the prediction device.

FIG. 4 is a schematic diagram illustrating a synchronous machine according to a first embodiment of the present invention, in which active power, reactive power, field control, rated armature current, and
FIG. 6 is a diagram showing each relationship between and the actual armature current.

FIG. 5 is a diagram showing the relationships among the rated armature current, the actual armature current, and the field weakening control start in the first embodiment of the present invention.

FIG. 6 shows the relationship between the rated armature current, the actual armature current, and the field weakening control start, respectively, in the first embodiment of the present invention, as shown in FIG. 5 and the overload limit start time (field weakening control start time). The line diagram shown about a different case.

FIG. 7 is a diagram showing, in comparison with each other, the relationship between the rated armature current, the actual armature current, and the field weakening control start and the withstand capacity of the armature winding in the first embodiment of the present invention. The time point when the armature current of exceeds the rated armature current is set as the 0 point on the time axis.

FIG. 8 is a diagram showing a third embodiment of the present invention, which is a connection showing an (I ² -1) t predicting device for directly and automatically predicting (I ² -1) t from an actual armature current. Fig.

FIG. 9 is a connection diagram showing a fifth embodiment of the present invention.

FIG. 10 is a connection diagram showing an overload limiting device in a conventional synchronous machine.

FIG. 11: Active power supply, reactive power supply of the conventional device,
The diagram which shows each relationship of field control, a rated armature current, and an actual armature current.

FIG. 12 is a diagram showing the relationship among the rated armature current, the actual armature current, and the field weakening control start in the conventional device.

FIG. 13 shows the relationship between the rated armature current, the actual armature current, and the field weakening control start in the conventional device.
FIG. 13 is a diagram showing a case where an overload limitation start time point (field weakening control start time point) is different from that in FIG. 12.

FIG. 14 is a diagram showing the relationship between the rated armature current, the actual armature current, and the field weakening control start, and the withstand capacity of the armature winding, in the conventional device. Is the time 0 when the point exceeds the rated armature current.

[Explanation of symbols]

1 synchronous generator, 2 excitation winding of generator, 4 automatic voltage regulator (AVR), 5 detecting means, 12 power system, 13 relay, 14 (I ² -1) t are obtained (I ²
-1) Accumulator, divider to obtain 14 ₁ I, 14 ₃ I
² to obtain a multiplier, 1 setter to obtain a 14 ₄ 1 14 ₅
Integrator for obtaining (I ² −1) t, 15 (I ² −1) t predictor, 15 _S (I ² −1) t predictor 15 output, 1
5 _1a to 15 _1j comparator, 15 _2a to 15 _2j relay, 1
5 _3a to 15 _3j (I ² −1) t prediction setter, 15 ₄ adder, 15 ₅ rated armature current setter, divider to obtain 15 ₆ I, numerical value setter to obtain 15 ₇ 3 15 ₈ ( I
+3) first adder, 15 ₉ 1 numerical value setter, 15 ₁₀ (I-1) second adder, 15 ₁₁
First multiplication means for obtaining (I + 3) (I-1), 15 ₁₂
Coefficient setting means for obtaining K, 15 ₁₃ K (I + 3)
Second multiplication means for obtaining (I-1) and, at 15A load (I ² -1) t predictor, 15B no load (I ² -
1) t prediction device, 16 adder, 16 _S output of adder 16, 17 (I ² −1) t operation setting device, 17 _S
(I ² −1) t output of operation setting device 17, 18 comparator, 19 control start timing automatic control means, 20 circuit breaker, 20 _a circuit breaker 20 a contact, 21 relay, 21 a relay 21 a contact, 21 b Relay 2
B contact of 1, I _A armature current, I _AR actual armature current, I _AR11 , I _AR12 , I _AR2 , I _AR3 , I _ART actual armature current, I _AT rated armature current, A _TL armature Winding tolerance curve, B armature winding margin area, t time,

Claims (16)

[Claims] 1. An overload limiting device for a synchronous machine for limiting excitation of the synchronous machine when the armature current of the synchronous machine exceeds a predetermined value, and detecting means for detecting the actual armature current, and this detecting means. 2. An overload limiting device for a synchronous machine, comprising: automatic limiting start timing control means for automatically changing the limiting start timing of the excitation in accordance with the magnitude of the actual armature current detected by. 2. An overload limiting device for a synchronous machine, which limits an overload of an armature winding of the synchronous machine when the armature current of the synchronous machine exceeds a predetermined value, and detects the actual armature current. Means and a limit start timing automatic control means for automatically changing the overload allowable time of the armature winding according to the magnitude of the actual armature current detected by the detecting means. Overload limiting device for synchronous machines. 3. An overload limiting device for a synchronous machine for limiting the excitation of the synchronous machine when the armature current of the synchronous machine exceeds a predetermined value. No-load limit start timing automatic control means for automatically changing the excitation start limit timing according to the magnitude of armature current, and the actual electric machine under the condition that the synchronous machine is connected to a load An overload limiter for a synchronous machine, comprising: a load start time limit automatic control means for automatically changing the excitation start time limit in accordance with the magnitude of the child current. 4. In an overload limiting device for a synchronous machine, which limits an overload of an armature winding of the synchronous machine when an armature current of the synchronous machine exceeds a predetermined value, the synchronous machine is not connected to a load. Limit start timing automatic control means for no load, which automatically changes the overload allowable time of the armature winding according to the actual magnitude of the armature current under the condition, and the synchronous machine is connected to the load A limit start timing automatic control means for load that automatically changes the overload allowable time of the armature winding in accordance with the actual magnitude of the armature current under Synchronous machine overload limiting device. 5. The no-load limit start timing automatic control means controls the excitation limit start timing when there is no load, and the load limit start timing automatic control means controls the excitation limit start timing when there is a load. 4. The synchronous machine according to claim 3, further comprising switching means for selectively switching between the no-load time limit start timing automatic control means and the no-load time limit start timing automatic control means. Overload limiting device. 6. When no load is applied, the limit start timing automatic control means for no load controls the excitation limit start timing, and when there is a load, the limit start timing automatic control means for load controls the excitation limit start timing. 5. The synchronous machine according to claim 4, further comprising switching means for selectively switching between the automatic limit start timing control means for no load and the automatic limit start timing control means for load. Overload limiting device. 7. The excitation limitation starts later when the actual armature current is smaller than when the actual armature current is large. An overload limiting device for a synchronous machine according to. 8. The overload allowable time of the armature winding is longer when the actual armature current is smaller than when the actual armature current is large.
4. The overload limiting device for a synchronous machine according to any one of 4 and 6. 9. The limit start timing automatic control means (I ² -1) when the excitation limit is started [where I is the P. of the actual armature current with respect to the rated armature current. U. [Value]], a plurality of integrated predicted values (I ² -1) t [where t is time] corresponding to the magnitude of the armature current are set in advance and correspond to the magnitude of the actual armature current detected by the detection means. 6. The limitation start time of the excitation is automatically changed based on the integrated predicted value (I ² -1) t that has been set.
5. The overload limiting device for a synchronous machine according to any one of 5 and 7. 10. The limit start timing automatic control means (I ² -1) when the overload limit is started [where I is the P.I. U. Value], the integrated predicted value (I ² −1) t according to the magnitude of the armature current
A plurality of [where t is time] is set in advance, and based on the integrated predicted value (I ² −1) t corresponding to the magnitude of the actual armature current detected by the detection means, 9. The overload limiting device for a synchronous machine according to claim 2, wherein the allowable load time is automatically changed. 11. The automatic limit start timing control means sets (I ² -1) [where I is the P.I. of the actual armature current to the rated armature current] when the excitation limit is started. U. Value] integrated prediction value (I ² −1) t is predicted and calculated, and the integrated prediction value (I ² −1) t [where t is corresponding to the magnitude of the actual armature current detected by the detection means The overload limiting device for a synchronous machine according to any one of claims 1, 3, 5 and 7, wherein the start time of limiting the excitation is automatically changed based on the time]. 12. The limit start timing automatic control means sets (I ² -1) when I start overload limitation [where I is P.I. U. Cumulative predicted value of the value] (I ² -1) t [where, t is the prediction calculation time, the magnitude corresponding to said accumulated prediction value of the actual armature current detected by the detecting means (I ² -1 9. The overload limiting device for a synchronous machine according to claim 2, wherein the allowable overload time of the armature winding is automatically changed based on t). 13. The limit start timing automatic control means is defined as follows when the excitation limit is started. [However, I is the P. of the actual armature current with respect to the rated armature current. U. Value], and the restriction start time of the excitation is automatically changed based on the calculated value. Restriction device. 14. The limit start timing automatic control means sets the following equation when the overload limit is started: [However, I is the P.V. for the rated armature current of the actual armature current. U. 9. The synchronous machine according to claim 2, wherein the overload allowable time of the armature winding is automatically changed based on the calculated value. Overload limiter. 15. The limit start timing automatic control means is K (I + 3) (I-1) [where I
Is the P. of the actual armature current relative to the rated armature current.
U. The value, K is a coefficient determined by a time constant at which the armature current changes when the excitation limit is started], and the excitation limit start time is automatically changed based on the calculated value. The overload limiting device for a synchronous machine according to any one of 1, 3, 5, and 7. 16. The limit start timing automatic control means is K (I + 3) (I-1) [where,
I is the P.I. for the rated armature current of the actual armature current.
U. Value, K is a coefficient that is determined by the time constant at which the armature current changes due to the start of excitation limitation], and the allowable overload time of the armature winding is automatically changed based on this calculated value. The overload limiting device for a synchronous machine according to any one of claims 2, 4, 6, and 8.