JPS6112460B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system joining device, and particularly to a system joining device suitable for joining an induction generator to a system.

Recently, in order to save energy, attempts have been made to use surplus steam in factories with boilers and waste heat in places with a large amount of waste heat to generate electricity to use energy more efficiently. In this case, induction generators have the characteristics of simple structure, robustness, and no need for an excitation device.
Since the equipment cost is low, it is most suitable as a generator for recovering the above-mentioned surplus energy.

By the way, the output of an induction generator is not good before it is connected to the grid, so there is no need to match the voltage, frequency, and phase between the grid and the generator before connecting it, unlike synchronous generators. If there is a large difference between the rotational speed of the induction generator, that is, the frequency of the induction generator and the grid frequency, a very large shock may be applied to the prime mover or generator when the induction generator is connected, or a large rush current may flow from the grid. This will have a significant negative impact on the prime mover, generator, and system. Therefore, it is necessary to match the rotational speed of the induction generator to the frequency of the grid before joining the system.

Therefore, conventionally, as shown in Figure 1, the prime mover 1
A permanent magnet generator 3 is connected to the rotation shaft of the induction generator 2, which is directly connected to the
Then, compare the frequency of system 6 obtained from PT5, swing indicator 7 according to the difference, visually adjust the output of prime mover 1, confirm that it is within the allowable value, and then shut it off. Container 8 was included.

However, in general, the allowable value for frequency deviation when adding an induction generator to the grid is very small, so the conventional grid insertion equipment described above requires a highly accurate and highly sensitive frequency difference transducer.
In addition to being expensive, the permanent magnet generator itself was also expensive, so the entire device had the disadvantage of being considerably more expensive than a synchronous verification device for a synchronous generator.

Furthermore, since the permissible value of the frequency deviation is small, it takes a lot of effort and time to perform the simultaneous operation while looking at the indicator 7, which has the disadvantage of placing a large burden on the operator.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive system integration device that can automatically integrate an induction generator in a short time and with high precision without placing a burden on the operator.

In order to achieve this object, the present invention detects the frequency of the induction generator and the frequency of the grid in a pulse manner, extracts the frequency difference between the two using an addition/subtraction counter, and performs uniform speed control of the induction generator. The present invention is characterized in that merging is performed when the frequency difference falls within an allowable value for a predetermined time.

Hereinafter, the present invention will be explained with reference to the embodiments shown in the figures.

FIG. 2 is a block diagram of a system integration device showing an embodiment of the present invention, and in the figure, the same reference numerals as in FIG. 1 indicate the same or corresponding parts.

The configuration shown in FIG. 2 is different from that shown in FIG. An addition/subtraction counter 10 is provided, and the system frequency is converted into pulses by a pulse converter 11 and inputted to the addition side of the addition/subtraction counter 10, while the pulse output of the rotation speed detector 9 is inputted to the subtraction side. , extract the frequency difference between the grid frequency and the induced power generation frequency, and convert this to BCD
(Binary coded decimal system) The controller 13 receives input from the display 12 to control the governor motor 14, and when the frequency difference falls within an allowable value for a predetermined time, the squeezer or disconnector 8 is activated. It is a point.

That is, a magnetic or photoelectric frequency detector that outputs a pulse proportional to the rotation of the prime mover 1 or induction generator 2 is used as the rotation speed detector 9, and its pulse output a and the pulse output of the pulse converter 11 are When b is input to the addition/subtraction counter 10, if the grid frequency and the generator frequency are equal, the rotation speed detector 9
Since the number of pulse outputs a of the pulse converter 11 and the number of pulse outputs b of the pulse converter 11 are the same, the addition/subtraction counter 1
The output c of 0 becomes zero. However, if the frequency of the generator is higher than the grid frequency, the addition/subtraction counter 10
The output c of is negative, and positive if the frequency of the generator is lower than the grid frequency.

The output c of this addition/subtraction counter 10 is displayed on the display 12.
1 is displayed on this display 12.
If you use one that resets every second, this display will be the difference between the generator frequency and the grid frequency.

If this display device 11 is capable of BCD digital output and polarity display output, this output can be taken out as a signal having each weight of 1, 2, 4, 8, . . . .

This signal is input to the controller 13, and the governor motor 14 is controlled according to the weight to match the generator frequency with the grid frequency, and when matching is achieved for a certain period of time, the breaker 8 is turned on. , the generator 2 can be synchronously connected to the grid 6 in the shortest possible time.

FIG. 3 shows a specific configuration example of the controller 13 for this purpose. 13A is a polarity display output d of the display 12 in order to rotate the governor motor 14 in the forward or reverse direction depending on the frequency of the generator and the grid. A relay that switches the polarity of the power supplies P and N applied to the governor motor 14 according to the following. 13B is a relay that operates when output e with weight 1 appears. Hereinafter, 13c is weight 2, 13D is weight 4, and 13E is weight 8. This is a relay that operates when the above outputs f, g, and h appear. 13G to 13J are governor motors 14, respectively.
It is a resistor that adjusts the current flowing through the governor motor 14 so that the rotation speed of the governor motor 14 becomes appropriate, and its size is 13
They are set in the order of G>13H>13I>13J. 13E is an off-delay timer that detects that the frequencies of the generator and the grid are within the permissible values for a certain period of time and outputs a joining signal i.

Now, assuming that the generator frequency is lower than the grid frequency and the difference in frequency is very large, the polarity display output d of the display 12 is zero, the relay 13A is de-energized, and its contacts 13A-1 and 13A are -2
is closed, and 13A-3 and 13A-4 are opened. Further, the relay 13E is excited by the output h having a weighting factor of 8 or more, and its contact 13E-1 is closed. As a result, a large current flows through the governor motor 14, causing it to rotate forward at high speed and increasing the generator frequency.

As a result, the frequency difference gradually decreases, and eventually the output h of the weighting coefficient 8 becomes zero, and the output g of the weighting coefficient 4 is generated this time, exciting the relay 13D. This closes the contact 13D-1 and current flows to the governor motor 14 through the resistor 13I.
At this time, since the resistance 13I is larger than 13J,
The current flowing through the governor motor 14 becomes smaller, and the rotation speed of the governor motor 14 becomes slower. Similarly, as the difference between the generator frequency and the grid frequency becomes smaller, the current flowing through the governor motor 14 becomes smaller, and when the generator frequency and the grid frequency fall within the allowable values, the output of the display 12 becomes zero, and the relay 13
B to 13E are all non-excited.

As a result, all contacts 13B-1 to 13E-1 are opened, current no longer flows through the governor motor 14, and the governor motor 14 is stopped.

Next, when the generator frequency is higher than the system frequency, a polarity display output d is generated from the indicator 12, and the relay 13A is excited. This allows that contact 1
3A-3, 13A-4 are closed, 13A-1, 13
A-2 opens, the polarity of the power supplies P and N applied to the governor motor 14 is switched, and the governor motor 14 is rotated in the reverse direction. The reverse rotation control of the governor motor 14 at this time is performed by each of the outputs e to h generated from the display 12 according to the frequency difference, as in the case where the generator frequency is lower than the system frequency.

As described above, when there is a difference between the generator frequency and the grid frequency, the relays 13B to 13E are excited by the outputs e to h of the display 12, and the governor motor 14
The generator rotates at a rotational speed corresponding to the frequency difference in a direction that eliminates the difference between the generator frequency and the system frequency, and controls the generator frequency so that the frequency difference is within an allowable value.

When the difference between the generator frequency and the system frequency falls within an allowable value, the relays 13B to 13E are de-energized.
If the relays 13B to 13E are not energized for a certain period of time, it can be determined that the generator frequency and the system frequency are approximately equal and that they may be combined. In order to detect this fixed time, off-delay timer 1
3F, each contact 13B-2 to 13E- of the relays 13B to 13E is provided there as shown in the figure.
2 are connected. Each of these contacts 13B-2
~13E-2 closes when each relay 13B~13E is energized. Therefore, off-delay timer 13F
is on because any of the contacts 13B-2 to 13E-2 are closed while there is a difference between the generator frequency and the system frequency, but when the difference falls within the allowable value, each Contacts 13B-2 to 13E-2 open and turn off when this state continues for a certain period of time.
When the off-delay timer 13F turns off, its contact 13F-1 closes, outputting the input signal i and connecting the sheath breaker 8. As a result, the generator 2 is joined to the grid 6 only when the difference between the generator frequency and the grid frequency is surely within the allowable value, and a safe joining operation is performed. In addition, relays 13A to 13E
The operating state may be reversed to that of the above embodiment, and a timer relay such as an on-delay timer may be used in place of the off-delay timer 13F.

As described above, according to the present invention, the induction generator is controlled at a uniform speed so as to be connected to the power grid.
Coupling operations can be performed automatically and accurately in a short time, eliminating much of the time and difficulty required to keep the frequency difference between the grid and the generator within tolerance, and reducing the burden on operators. In addition to reducing the burden, the additional device can be constructed from a commercially available product compared to conventional devices, so it can be constructed simply and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional system integration device, FIG. 2 is a configuration diagram of a system integration device showing an embodiment of the present invention, and FIG. 3 is a specific configuration example of the controller shown in FIG. 2. FIG. 1... Prime mover, 2... Induction generator, 3... Permanent magnet generator, 4... Frequency transducer, 5
...PT, 6...System, 7...Indicator, 8...Shipping switch, 9...Rotation speed detector, 10...Addition/subtraction counter, 11...Pulse converter, 12...Display device, 13...Controller, 13A~13E...Auxiliary relay, 13F...Off delay timer, 13G~
13J...Resistor, 14...Governor motor.

Claims (1)

[Claims] 1. When the difference between the system frequency and the rotational speed of the induction generator falls within an allowable value, a system integration device that connects the induction generator to the system includes a pulse converter that converts the system frequency into pulses. , a rotation speed detector that detects the rotation speed of the induction generator and outputs a pulse, a pulse output from the pulse converter and a pulse output from the rotation speed detector are input, and the system frequency and the induction generator are inputted. An addition/subtraction counter that outputs a signal according to the difference from the rotation speed, a plurality of relays that respond to each value of this addition/subtraction counter, a plurality of resistors each selected by the plurality of relays, and a A governor motor rotates at a speed according to the resistance to control the rotation speed of the induction generator, and after a predetermined time has elapsed since the value of the addition/subtraction counter becomes a predetermined value or less and the plurality of relays are all in the same operating state. A system joining device comprising: a timer relay that changes an operating state, and joining the induction generator to the system according to a change in the state of the timer relay.