JPS63220722A - Automatic synchronous closing apparatus of variable speed generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a variable speed power generation system, and particularly to a variable speed pumped storage power generation system using an AC excitation method for the secondary excitation coil of a wound induction generator motor. This invention relates to an automatic synchronization entry device.

[Conventional technology]

When the load on the power system is light and there is surplus power at other power plants, this can be used to store water by pumping it to a pond at a high altitude, which is necessary when rivers are dry or when the load is heavy. Pumped storage power generation is known as a method of generating electricity using stored water at certain times of the year.In general, a synchronous generator-motor is used as a generator.

On the other hand, conventional pumped storage power generation systems use synchronous machines, so the load cannot be adjusted during pumping, and
During power generation operation and pumping operation, there is a drawback that the efficiency of the power generation system changes due to changes in the generated power required by the system and the pumping height during pumping.

For this reason, research is underway to operate the above system at maximum efficiency regardless of the power generated or the lift height.

In order to achieve the above objective, we replaced the synchronous machine conventionally used as a pumped storage generator with an induction machine with secondary excitation (i.e.
It is operated by a wound wire induction machine). Research is underway to realize a so-called variable speed power generation system.

Here, the variable speed power generation system will be explained.

Figure 3 shows the principle of the variable speed power generation system.

In the wound induction machine shown in FIG. 11, 100 represents a stator and 101 represents a rotor. 102a to 102c are windings of each phase of a, b, and c of the stator 1.

103a to 103c indicate windings of each phase of a, b, and c of the rotor 2. If the rated frequency is j and the slip is S, then
The speed of the rotor 2 is f(1-8), and by exciting the secondary windings 103 a to 103 c of the first rotor 101 at a frequency of S, the rotating magnetic field of the rotor 2 has a slip S.
is rotated at zero (synchronous speed), and the rotation speed of the rotor 101 is the same as the speed of the rotating magnetic field of the rotor 100],
Measured from 04.

The output glass frequency inspection device 105 detects the frequency, and then the frequency/voltage converter 106 generates a voltage according to the frequency, and this voltage is applied to the secondary windings 6a to 6c to excite them. By doing as follows, the primary winding 102 is always connected even when operating at any rotation speed.
a to 102c can generate a voltage at the system frequency. That is, in the example of FIG. 1, the rotating magnetic field of the rotor 101 is:

f(1-5)+fB=f (1), and regardless of the slip S, an output at the rated frequency can be obtained.

The literature regarding the above-mentioned variable speed power generation system is the 1984 National Conference of the Institute of Electrical Engineers of Japan (March 28-30, 1982).
There is a paper titled "Variable Speed Operation Characteristics of Large-Capacity Synchronous Motor" (Japanese Publication No. 41M) Paper & 553 r, but this document does not disclose any specific control method.

[Problem that the invention seeks to solve]

Now, the problem here is the automatic synchronization device for bringing the variable speed generator into the grid. That is,
Conventionally, a synchronous machine is used.

In order to synchronize the grid, it must be done when the voltage magnitude, frequency, and phase match between the grid and the generator. An example of a conventional automatic synchronizer is " Hydroelectric power plant (Published by Denki Shoin (1932)
April 10, 1999), pages 321 and 314, however.

None of the above-mentioned known documents describes an automatic synchronization device for a variable speed power generator using a wound induction generator motor.

Therefore, one aspect of the present invention is the winding induction generator f! It is an object of the present invention to provide an automatic synchronization start-up device that can smoothly and reliably turn on a variable speed power generator using an electric motor with a simple configuration.

[Means for solving problems]

In order to solve the above objects and achieve the objects of the present invention, the present invention provides a wound induction generator-motor connected to the grid via a parallel closing circuit breaker, In the variable speed power generating apparatus, the variable speed power generating apparatus includes a phase detector that detects a phase, and an excitation control device that controls an excitation current amount of a secondary excitation circuit of the generator motor based on the detected phase signal of the suboptimal frequency. a grid voltage detector that detects the voltage of the generator motor, an output voltage detector that detects the output voltage of the generator motor, and a closing control device that outputs a closing command signal to the parallel closing circuit breaker when both detected voltages match. It is characterized by having the following.

According to a more specific aspect, the closing control device controls the starting ft! based on the detected voltage from the output voltage detector. a starting element confirmation device that outputs an equalizing pressure start closing signal when the output voltage of the motor is established; a equalizing pressure start switch that is turned on in response to the equalizing pressure start closing signal; and a voltage equalizing start switch that detects the system voltage through the equalizing pressure starting switch. and a voltage balancing device that receives detection signals from the output voltage detector and the output voltage detector and outputs a control signal according to the difference between the system voltage and the output voltage to the excitation control device.

[Effect]

In other words, when excitation control is applied to the secondary coil of a single-winding induction generator motor, the excitation control is performed on the secondary coil based on a slip frequency phase signal with respect to the system frequency, and even if the speed of the rotor containing the secondary coil changes, power generation does not occur. The frequency and phase of the output voltage on the primary side of the machine are controlled to match those of the grid. Therefore, in this case, even if the generator-motor is not connected to the system, the generator-motor is already controlled so that its primary output voltage matches the system in both frequency and phase as described above, so it is connected to the system. The condition required when turning on the generator motor is that it has a function to match the output voltage of one generator motor to the voltage of the grid (equal voltage).

From the above, according to the present invention, the magnitude of the grid voltage is detected by the grid voltage detector, and on the other hand, the output voltage of the generator motor is detected by the output voltage detector. The control device controls the parallel closing circuit breaker to close when the two detected voltages match.

As a result, there is no need to predictably output a closing command in order to synchronize with the grid frequency and phase in anticipation of the loss time required for the circuit breaker closing operation, unlike in conventional synchronizing devices for synchronous machines. Since it is sufficient to output a closing command using only the pressure state, the possibility of erroneous closing can be significantly reduced. This means that when the variable speed power generation device is considered as a means of compensating for fluctuations in the system, it can quickly perform the compensation function, thereby contributing to improving the stability of the system.

Moreover, according to a specific aspect, since the voltage balancing device is provided, it becomes possible to automatically compensate for voltage fluctuations in response to the difference between the grid voltage and the output voltage after the power supply is connected to the grid.

〔Example〕

Next, one embodiment of the present invention will be explained based on the drawings.

First, FIG. 1 shows the overall configuration of an automatic synchronizer and a variable speed generator according to the present invention.

The main transformer 2 is connected to the power system 1 and to the primary side of the induction generator motor 3 via the parallel circuit breaker 5 . The secondary side of the induction generator motor 3 is excited with alternating current, and the excitation power is supplied to the power system 1 (during power generation, the induction generator motor 3 output). The excitation power source has the same frequency as the power system frequency, but is converted into an AC excitation current having a three-phase slip frequency by the power converter 7 via the excitation transformer 11, and is used to generate the induction generator motor 3. In this embodiment, a microconverter is used as the power converter 7.

In order to generate an excitation current with the above-mentioned slip frequency, it is necessary to have a device that detects the phase of the slip frequency currently in operation. The primary side of the detector 4 is excited.

This phase detector 4 is a kind of induction generator, and since the rotor is coaxial with the rotation axis of the induction generator motor 3, if the negative side is excited at the power system frequency, the slip frequency will be output as the secondary side output. This means that the waveform can be detected. The slip frequency detected in this way is taken into the excitation control device 8 via the insulation transformer 14.

The excitation control unit W18 executes various control functions, and finally outputs a signal to the automatic pulse phase shifter 10 as a thyristor firing angle signal 102 in the form of superimposing the results on the Suberi frequency. The automatic pulse phase shifter 10 is connected to the power converter 7
In response, a thyristor firing pulse signal 103 is output.

Further, the output branch signal of the voltage transformer 12 and the primary terminal voltage of the generator are connected to the automatic synchronizer 9 via the voltage transformer 1113.
Enter. The output of the automatic synchronizer 9 is a power up signal 10
0 and a voltage reduction signal 101, which are output to the excitation control device 8.

When the generator motor 4 is initially started, it is driven by a water wheel (not shown) directly connected to the rotor of the induction generator 3.

Excitation starts when a certain number of rotations is reached, but since the phase detector 4 has already been excited before the start of excitation, a slip phase signal has been established. Due to the excitation, a voltage is generated on the primary side of the induction generator motor 3, and it is ready to be connected to the grid.

The automatic synchronization device will be explained using FIG.

Items with the same symbols as in FIG. 1 indicate the same equipment.

As mentioned above, once the excitation is started and the generator output voltage is established, the starting element confirmation bag in the automatic synchronizer 9! ! 20 turns on the pressure equalization start switch 23 of the automatic synchronizer.

This ON command starts the operation of the voltage balancing device 21, and compares the voltage on the power system 1 side with the generator output voltage.
If the generator output voltage is lower than the system 1 side, a voltage increase command 100 is output to the excitation control device 11f8.
By increasing the generator output target voltage set value, it can be brought closer to the grid side voltage value. In the opposite case, a voltage reduction command 101 is output, lowering the target voltage setting value and bringing it closer to the grid side voltage value.

After implementing such feedback control, when the grid voltage and the generator voltage almost match, the voltage balancing device 2
1 outputs a so-called closing signal that excites the circuit breaker 5 closing coil 5c via the signal output device 22.

At this time, there is no need to consider the operating time of the closing coil 5C, the operating time of the circuit breaker 5, etc., and it is sufficient to simply give the closing signal when the two voltage values match.

According to this embodiment, as described above, it is possible to synchronously connect the generator motors to the system in parallel using only the pressure equalization function. Also,
Originally, the phase of the slip frequency, which is essential for control, is detected and the AC excitation signal is generated based on this, so special phase control is not required for system parallel input.

[Effect of the invention J] According to the present invention, when introducing the induction generator motor into the power system in synchronous parallel fashion, there is no need to perform the conventional one-phase control with uniform speed function, and it is only necessary to perform equal pressure control. Well, W1
It has the effect of being monogamous.

In addition, even in systems where the power grid is weak and the frequency is unstable, a system with this configuration can detect a slip frequency commensurate with the unstable frequency and immediately perform excitation control. The automatic synchronous parallel input operation, which has been considered difficult in this type of system, can be easily performed using the same configuration as the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment according to the present invention. FIG. 2 is a block diagram showing details of the automatic synchronization device, and FIG. 3 is an explanatory diagram showing the principle of the variable speed generator. DESCRIPTION OF SYMBOLS 1... Power system, 2... Main transformer, 3... Induction generator m motor, 4... Phase detector, 5... System parallel circuit breaker, 7... Power converter, 8... Excitation control device, 9
... automatic synchronizer, 10 ... automatic pulse phase shifter, 1
2... Voltage transformer (system voltage detector), 13... Voltage transformer (output voltage detector), 20... Starting element confirmation device, 21... Voltage balance device, 22... Signal Output device, 23... Equal pressure start switch.

Claims (1)

[Claims] 1. A wound induction generator motor connected to the grid via a parallel closing circuit breaker, a phase detector that detects the phase of the slip frequency of the generator motor with respect to the grid frequency, and a detected slip A variable speed power generator comprising: an excitation control device that controls an excitation current amount of a secondary excitation circuit of the generator motor based on a frequency phase angle signal; A variable speed variable speed control device comprising: an output voltage detector that detects the output voltage of a generator motor; and a closing control device that outputs a closing command signal to the parallel closing circuit breaker when the two detected voltages match. Automatic synchronization device for power generation equipment. 2. In the device according to claim 1, the closing control device includes a starting element check that outputs an equal pressure start closing signal when the output voltage of the generator motor is established based on the detected voltage from the output voltage detector. a voltage equalizing start switch that is turned on by the equalizing pressure start input signal; and a voltage equalizing start switch that receives detection signals from the system voltage detector and the output voltage detector through the equalizing pressure start switch, and detects the system voltage and the output voltage. An automatic synchronization device for a variable speed power generator, comprising: a voltage balancing device that outputs a control signal according to a difference between the two to the excitation control device.