JPH0221007B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention detects reactive power and sequentially turns on and off power factor correction capacitors to adjust the power factor of the grid. The present invention relates to a sequence control device for improvement capacitors (hereinafter simply referred to as a capacitor group).

<Prior Art> This type of control device has a configuration as shown in FIG. Although FIG. 1 shows a capacitor having three groups for simplicity, the present invention is not limited to this and any number of groups can be used.

To outline FIG. 1, reactive power is detected by a reactive power detection circuit 1 based on the current and voltage obtained from the line L of the system by a voltage transformer CT and a voltage transformer PT.

If the detected reactive power is delayed, the delay determination circuit 2 determines this.

The timer circuit 4 is started by the operation of the discrimination circuit 2, and is set up after T seconds (arbitrary). From this point on, pulses are emitted at regular intervals (for example, 5 seconds).

This pulse drives the step circuit 27 via the AND circuit 11, and the output of the step circuit 27 is sequentially passed through the AND circuits 12 to 14 to the closing relays C1, C2,
C3, and since these operate, contact C1
1, C21, C31 are closed, switches 142, 24
2,342, is injected into the capacitor groups C1 to C3.
is inserted into line L.

By inserting this capacitor group, the power factor of the line L is successively improved.

If the reactive power of the line L falls within a specified range after the capacitor group C3 is inserted, the subsequent stepping operation is stopped.

Note that the parallel circuit of the auxiliary contacts 142a to 342a of the switch and the parallel circuit of 142b to 342b are circuits for determining whether or not a controllable switch exists.

If the reactive power becomes more advanced than the set value with the passage of time, the advance determination circuit 3 determines this.

Then, timer circuit 5 operates in the same way as timer circuit 4.

Fixed time from timer circuit 5 (e.g. 5 seconds)
The interval pulses are passed through the AND circuit 6 to the step circuit 2.
6, the trip relays T1, T2, and T3 operate in the same manner as described above, and the switches 142,
242 and 342 are sequentially opened and capacitor group C
1, C2, and C3 are separated from the line L.

As a result, the reactive power on the line L becomes delayed again.

When the reactive power of the line L falls within a specified range, the subsequent stepping operation is stopped.

By repeating such operations, the line reactive power is maintained at a specified value.

<Problem to be solved by the invention> Now, there is no problem if the reactive power of the line can be covered by the operation of a limited number of capacitor groups (for example, 3 groups) as described above, but if the load connected to the line increases As a result, the number of capacitors must be increased accordingly.

On the other hand, since the number of control groups in the control device is fixed, it is necessary to separately manufacture a new device that includes the additional capacitor group, or prepare a separate device for only the added capacitor group. Conceivable.

However, the former case is uneconomical, and the latter case has problems in that the sequence between the existing installation and the expansion becomes complicated.

<Means for Solving the Problems> The present invention has been made in view of the above-mentioned points, and includes an adapter closing control relay CX in the stepping circuit 27 of the existing control device, and an adapter tripping control relay CX in the stepping circuit 26. Add each relay TX and make step circuit 2
9 and an adapter closing control relay CY operated by the outputs of the stepping circuit 28 and the stepping circuits 29 and 28;
Adapter 30 with adapter trip control relay TY and keep relay X2 operated by adapter closing control relay CX and reset by CY
By simply adding the keep relay X1, which is operated by the adapter trip control relay TX and reset by TY, it is possible to quickly respond to the aforementioned expansion.

<Function> Adapter closing control relays CX and CY operate with the last output of stepwise circuits 27 and 29, and adapter tripping control relays TX and TY operate with stepwise circuits 26 and 28.
The closing control relay X2 operates after all the existing capacitor groups are turned on, and the trip control relay X1 operates after all the existing capacitor groups are tripped.

The step circuit 27 is activated by the operation of the keep relay X2.
Since the switch is switched from to the step circuit 29, it is possible to control the closing of the additional capacitor group, and when all the additional capacitor groups have been closed, the keep relay X2 is restored, so that it is again possible to control the closing of the existing capacitor group.

In other words, when the delayed reactive power still does not fall to the specified value even after all the existing capacitor groups have been turned on, the additional capacitor group can be turned on.

Regarding trip control, after tripping all the existing capacitor groups, keep relay
1, the stepping circuit 26 to the stepping circuit 28
Since the switch is switched to , it is possible to control the tripping of the additional capacitor group, and when all the additional capacitor groups have been tripped, the keep relay X1 is restored, so it is possible to control the tripping of the existing capacitor group again.

In other words, even if all the existing capacitor groups have been tripped, the additional capacitor group can be tripped when the reactive power has not yet reached the specified value.

<Example> Figure 2 shows an example of the present invention, in which there are three existing capacitor groups and three additional groups. The determination is the same as in the case of FIG.

In addition, the parallel circuit of the auxiliary contacts 142a to 342a of the switch and the parallel circuit of 142b to 342b are connected to the existing capacitor group switch, and
The parallel circuit 42a and the parallel circuits 442b to 642b are circuits for determining whether or not a controllable switch exists in the expansion capacitor group switch.

The main difference from Fig. 1 is that the adapter closing control relay CX is placed next to the closing relays C1, C2, and C3 of the existing capacitor group, and the tripping relays T1, T2, and
Added an adapter trip control relay TX after T3, a step circuit 29 and closing relay C4 for controlling the closing of the additional capacitor groups C4 to C6,
C5, C6 and adapter closing control relay CY,
With the addition of an adapter for controlling the order of additional capacitor groups consisting of a step circuit 28 for trip control, trip relays T4, T5, T6, and an adapter trip control relay TY, and keep relays X1 and X2. be.

To outline the operation in Figure 1, if the reactive power on line L still does not change to an increase even if the existing capacitor groups C1, C2, and C3 are sequentially inserted into line L, the operation of adapter closing control relay CX Therefore, the contact CX1 is closed and the keep relay X2 is operated.

Then, switches 442 to 642 are connected to the contact X22.
Since the parallel circuits of the auxiliary contacts 442b, 542b, and 642b are connected in series, an output is output from the AND circuit 21 each time the timer circuit 4 receives a pulse.

As a result, the step circuit 29 sequentially outputs step outputs, and the AND circuits 22 to 25 also sequentially output step outputs.

For this reason, the closing relays C4, C5, C6 and the adapter closing control relay CY operate in order, so these contacts C41, C51, C61 and CY1
By closing the switch 442, 542, 6
42 is injected, and the capacitor groups C4, C5, C6
is inserted into line L.

And when contact CY1 closes, keep relay X2
(Returning coil R) operates to open its contact X22 and the subsequent stepping operation is stopped.

By inserting the capacitor groups C1 to C6, the reactive power of the line L is maintained within a specified range.

If the reactive power on the line L starts to increase due to a decrease in load, the capacitor groups are sequentially separated from the line L as described above.

Through such repetition, the power factor of the line L is improved.

<Effects of the Invention> As detailed above, the device of the present invention has the advantage that when adding a group of capacitors, it can be quickly handled by simply adding an expansion adapter and a keep relay to the conventional device.

[Brief explanation of drawings]

FIG. 1 is a connection diagram showing the configuration of a conventional device, and FIG. 2 is a connection diagram showing an embodiment of the present invention. CT...Instrument current transformer, PT...Instrument transformer, L...
Line, 1... Reactive power detection circuit, 2, 3... Discrimination circuit, 2, 5... Timer circuit, 6 to 25... AND circuit, 26 to 29... Step circuit, 30... Extension adapter, X1, X2... Keep relay , C1 to C6...
Power factor improvement capacitor group, 142-642...Switch, CX, CY...Adapter closing control relay, C1
~C6... Closing relay, T1 to T6... Tripping relay, TX, TY... Adapter tripping control relay.

Claims (1)

[Claims] 1. A circuit 1 that detects reactive power on a line; Circuits 3 and 2 that proceed from the reactive power and a set value and determine a delay; A timer circuit 5 that outputs pulses at fixed time intervals;
4, step circuits 27 and 26 that issue commands to turn on and trip the power factor improvement capacitor each time a pulse is received from the timer circuits 5 and 4, and are operated by the last output of the step circuits 27 and 26. The timer circuits 5, 4 are connected to the adapter closing control, adapter tripping control relays CX and TX, and the power factor correction capacitor that is added separately from the power factor correction capacitor.
Stepping circuits 29, 28 that issue commands to turn on and off every time a pulse is received from the
an expansion adapter 30 equipped with an adapter closing control and adapter tripping control relays CY and TY that are operated by the last output of the adapter 30; Keep relay X for closing control and tripping control reset by closing control and tripping control relays CY and TY installed in
1, X2, and a sequential control device for power factor improvement capacitors.