JPH02136044A - Station bus switching control system - Google Patents

Abstract

PURPOSE:To improve the power reliability of station auxiliary machines by monitoring the actual operating load capacity always and by computing and monitoring the margin of a transformer. CONSTITUTION:The total QT of the actual load operating capacity QTH1 of No.1 station transformer 5 and the actual load operating capacity QTS of a starting transformer 10 is an operating load capacity to be power-supplied by said starting transformer 10 at the time of No.1 unit trip. When the rated capacity QS of the starting transformer 10 is compared with said QT and QS>=QT, the ON permit signal of a bus-connecting breaker 12 is made; and when QS<QT, the short-time overload capacity characteristic curve QSalphat of the starting transformer 10 is then compared therewith. Such computation and comparison are conducted moment by moment; the result before one cycle is stored always; and when No.1 unit trip signal is given, a house bar is switched on the basis of the stored result so that said switching can be performed with no delay of time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a busbar switching system equipped with three or more power supplies,
In particular, the present invention relates to an in-plant busbar switching control system suitable for strengthening the securing of in-house auxiliary equipment power supply in a plant.

[Conventional technology]

Conventional in-station busbar switching employs a method in which if the power supply that is constantly in use experiences a power outage for some reason, the power supply is switched to another power supply according to predetermined interlocks for opening and closing circuit breakers. For example, JP-A-55-1390
As described in Publication No. 36, a bus connection breaker that detects a power outage in a constantly used power source and connects to other buses under the condition that the power receiving circuit breaker of the constantly used power source is open. was turned on to secure power for the station's auxiliary equipment.

As described in Japanese Unexamined Patent Publication No. 55-139036, methods for improving the reliability of conventional bus switching have been discussed, but the bus switching pattern is selected based on the actual operating conditions of the transformer. However, there is no discussion of in-station bus bar switching control that strengthens the securing of in-station auxiliary equipment power supply.

Regarding the case of on-site power supply of thermal power plants, the conventional technology is
This will be explained using figures. Generally, one common power source is installed for two power generation units. The auxiliary equipment 1 and 2 of the own unit necessary for power generation are connected to the station buses 7 and 8 to which the outputs of the generators 3 and 4 of the own unit are connected via the station transformers 5 and 6.
The auxiliary equipment 9 connected to and common to the two units is the starting transformer 1.
It is connected to a common bus line 11 whose power source is 0. usually,
When starting the power generation unit, consider the case of starting the No. 1 generator 3. First, power is supplied from the common bus 11 to the unit auxiliary equipment 1 via the bus bar connection breaker 12, and the generator 3 is in a state where it can generate electricity. Then, the main circuit breaker 13 is closed and the main transformer 1
4 to the grid 15 to take up the load. Next, the power for the unit auxiliary equipment 1 is supplied from the output of the generator 3 via the station transformer 5 by turning on the station power receiving circuit breaker 16 and simultaneously opening the busbar communication circuit breaker 12. In the case of a power generation unit stoppage, conversely, the common bus fil
It is supplied from the starting transformer 10 via l. In addition, if the power generation unit trips for some reason, in order to safely stop the unit, the in-station power receiving circuit breaker 16 is opened with a unit trip signal, and the busbar contact circuit breaker 1 is opened under that condition.
2 is turned on to secure power from the starting transformer 10 to the reunit auxiliary equipment 1 via the common bus 11.

Generally, the rated capacity of the station transformers 5 and 6 is the station bus 7 and 8.
The capacity is sufficient to cover the maximum operating load capacity of the unit auxiliary equipment 1 and 2 connected to the common bus 11, or the capacity is sufficient to back up the power source of the common auxiliary equipment 9 connected to the common bus 11 in the event of a failure of the starting transformer 10. In addition, the rated capacity of the starting transformer 10 is the capacity that can cover the maximum operating load capacity of the common auxiliary equipment 9 connected to the common bus 11 and the operating capacity of the unit auxiliary equipment 1 and 2 at the time of starting for one unit, or It is determined by the larger of the maximum operating load capacity of the auxiliary machine 9 and the sum of the capacity that can back up the operating capacity of the unit auxiliary machines 1 and 2 during 100% output operation for -units at the time of unit trip.

Therefore, there is no bus switching interlock that connects the No. 2 station bus #17 to the No. 2 station bus 8 via the common bus 11, and vice versa. Furthermore, the power source for starting the units does not have a bus bar switching interlock that allows two units to be started at the same time. Furthermore, when two units trip simultaneously, the station bus s7 is transferred from the common bus 11.
There is no bus switching interlock that allows backup to the station bus 8 and the station bus 8 at the same time.

As a result, depending on the operating state of the unit, there may be cases where the load capacity is small, that is, even if the rated capacity of the transformer has a margin, bus bar switching cannot be performed and power supply cannot be secured.

[Problem to be solved by the invention]

In the above conventional technology, the rated capacity of the station transformer and starting transformer is determined as the capacity that can cover the maximum load capacity. Regardless, it is uniquely determined by the interlock.

Therefore, even if the rated capacity of the transformer has enough margin to back up other buses compared to the actual load operating capacity,
There was a problem with not being able to back up.

The purpose of the present invention is to constantly monitor the actual operating load capacity and constantly compare it with the possible operating capacity of the transformer to determine whether backup to another bus is possible. An object of the present invention is to provide an in-station bus switching control system that can improve the reliability of an in-station auxiliary power supply that performs in-station bus switching by selecting a load selection/cutting pattern to enable the in-station bus switching.

[Means to solve the problem]

The above purpose is to constantly monitor the operating load capacity of each bus, further monitor the current bus operation status, and determine the load capacity of each transformer after backup in the expected bus switching.
Compare this with the possible operating capacity of the transformer, determine whether switching is possible, issue a command to implement bus switching if possible, and if not, how many loads should be selectively cut off to make it possible. This is achieved by monitoring the operating state of the load to determine whether it is possible to do so.

[Effect]

The present invention calculates the operating load capacity of each bus by constantly monitoring and calculating the voltage and current of each bus, and the current bus linkage state is the open/close state of each power receiving circuit breaker and bus connection circuit breaker. Based on this, the expected bus linkage pattern is determined, and the total load capacity that will be applied to each transformer when the bus links are connected is calculated. The comparison is made to determine whether switching is possible, and if it is possible, a bus switching signal is issued. If not, the operating status of the load is determined from the open/close status of each load's shutoff diagram, and the load is prioritized in advance and the group For the configured loads, and from the operating capacity of each auxiliary machine input in advance, it calculates and determines which group of loads should be selectively cut off, and if possible, selects the load. Issues a cutoff command and busbar switching command.

〔Example〕

An embodiment of the present invention will be explained with reference to FIGS. 1 to 3.

FIG. 1 is a diagram obtained by adding what is necessary for explaining the present invention to FIG. 4 used for explaining the prior art. Components other than those explained in FIG. 4 will be explained below. 23, 27
．． 25 shows a detector for measuring the bus voltage of each bus 7, 8.11, and 24° 28.26, each transformer 5, 6.10
This is a detector that measures the load current. QHII QH2
, Q s indicates the rated capacity of each transformer 5, 6.10, and 1
6, 21° 20 indicates a power receiving circuit breaker for each bus bar 7, 8, 11.

In addition, 12.22 shows the busbar communication circuit breaker between the first station bus 7 and the common bus 11 and the second station bus 8 and the common bus 11.
LHII~L+zn are the load breakers of the unit auxiliary equipment 1 connected to the No. 1 internal bus 7, LHzs~LH2n are the load breakers of the unit auxiliary equipment 2 connected to the No. 2 internal bus 8, and LSl~ Lsn indicates a load breaker of the common auxiliary machine 9 connected to the common bus 11. M H11~M Hl
n is the pre-stored operating load capacity of each auxiliary machine of No. 1 unit auxiliary machine 1, MH21=MH2n is the pre-stored operating load capacity of each auxiliary machine of No. 2 unit auxiliary machine 2, and MSI ~MSn indicates the operating load capacity of each auxiliary machine of the common auxiliary machine 9, which is stored in advance. I, II,
III indicates an auxiliary machine group that is divided into three groups in this example in order of priority for selective cutoff of the load of the first unit auxiliary machine 1.

QHLll r QHLx2+ QHII3 are load breakers LHII to L corresponding to each auxiliary equipment group I, II, and III.
Operating load capacity of auxiliary equipment when Ht n is closed M Ht
The group load capacity is the sum of t~M H1n. QHL
I indicates the total capacity of Q) ILII, Q) IL121QHL13. The configuration of the auxiliary equipment group is omitted for No. 2 unit auxiliary equipment 2, but QHL2.11 QHLzz
+ QHL23 and QHL4 are the first unit QHLI
II Q+-+t, tz, QHII3 and Q) ILI
It corresponds to Similarly, Qst represents the load capacity that is the sum of the operating load capacities M S 1 to M3n of the auxiliary machines whose load breakers LSI to LSn of the common auxiliary machine 9 are in the closed state.

FIG. 2 is a diagram conceptually showing the process leading to bus bar switching according to the present invention. In Fig. 2, the detection unit always uses detector 2.
3, 27.25 and the bus voltage V1°V2. Vs and the transformer load current A1. A'2, A
s, and further check the current bus operation using the power receiving circuit breaker 16.
, 21.20 and the busbar connection circuit breakers 12.22, and further monitor the operating conditions of each auxiliary equipment 1, 2, 9, load breakers L)+11 to Lotn, LH2 are used.
The open/close states of 1 to L Hen and Lsz to Lsn are monitored and sent to the comparison calculation section. In the comparison calculation section, the rated capacity Qot+QHzrQ of each transformer 5゜6.10 is calculated in advance.
s, each transformer 5, 6, which is allowed for short-term operation.
10 overload capacity characteristic curve Q old α(t) r Q)+
2α(t).

Qscc(t) and operating load capacity M Hl 1 to MHsn of each auxiliary machine 1, 2.9, Mozt=M
H2n + M S1 to M s n are input, and are calculated together with the data sent from the detection unit to determine whether bus switching is possible in each of the possible bus switching cases based on the actual operating load capacity. and the transformer's possible operating capacity, and further determines whether selective load shedding is necessary, and sends the result to the storage unit. The storage unit stores only the latest information of comparison operation results that are sent cyclically,
When a busbar switching factor occurs, the currently stored result is sent to the interlock section of the busbar contact circuit breaker 12.22, and the busbar switching is performed. By doing so, there is no time delay in the detection and comparison calculation section, and bus bar switching can be performed immediately.

FIG. 3 is a flowchart showing details of bus bar switching control in a specific embodiment of the present invention. In this embodiment, it is assumed that the No. 1 unit is operating at 50% load and the No. 2 unit is starting up. In this case, the status of each circuit breaker is the power receiving circuit breaker 16.
is closed, 21 is open, and 20 is closed, and the busbar connection breaker 12 is open and 22 is closed. In other words, the - station transformer 5 supplies power to the operating auxiliaries of the unit auxiliary equipment 1 connected to the station bus 7. In this case, it is 50% unit load operation and the actual operating load capacity QT calculated as 'JT;
s Relatively small compared to s. In addition, the starting transformer 1o is connected to the common auxiliary equipment 9 connected to the common bus 11 and the No. 2 station bus 8.
Power is supplied to the operating auxiliary equipment of the unit auxiliary equipment 2 connected to the unit auxiliary equipment 2 when the unit is started. In this case as well, the unit is started up, and the actual operating load capacity QT5 calculated by f〒XVsXAs is smaller than the transformer capacity Qs. The busbar switching assumed in this state is a busbar switching in which the power receiving circuit breaker 16 is opened and the busbar contact circuit breaker 12 is closed in order to secure the power supply of the No. 1 unit auxiliary equipment 1 when the - unit trips, or a starting transformer Open the power receiving circuit breaker 20 at the time of failure of the device 10,
Bus bar switching that closes the bus bar contact circuit breaker 12 can be considered.

In this figure, the case when the - number unit trips is taken as an example. In the conventional technology - in the unit starting state,
There is no interlock in which power is supplied to other units when tripping while supplying power to the starting auxiliary equipment, and bus bar switching is not performed, but in the present invention, the following is done.

The sum QT of the actual load operating capacity QTHI of the No. 1 in-station transformer 5 and the actual load operating capacity QTS of the starting transformer 10 becomes the operating load capacity to which the starting transformer 1o should supply power when the No. 1 unit trips. This QT and the rated capacity Qs of the starting transformer 10
If QS>QT, bus bar connection breaker 12
If Qs<(h, then primary, compare it with the short-time overload capability characteristic curve Qsα(1) of the starting transformer 1o. If Q,α>QT, the busbar connection is cut off. At the same time as issuing a closing permission signal for the transformer 12, the operation overload rate and allowable operation time of the starting transformer 10 are displayed.
If it is 1, load breaker of auxiliary equipment 1 in No. 1 plant is old 1~L H
Operating load capacity of auxiliary equipment in closed state, MHI
Based on the total operating capacity QHLtt of the auxiliary equipment that corresponds to the selected shutoff auxiliary equipment group ■ among I~Mo2□, compare Qs, QT QHt, and engineering x. , >QT QHLII, a closing permission signal for the busbar communication circuit breaker 12 is issued, and a shutdown command for the auxiliary equipment group I is issued. If Q S < Q T - QHLxl, Qot calculated in the same way as QoLzt, Qs and Qt from 1z Q)lLll Q)lL12
Qs > QT-QHLll QHLI
If it is I, a closing permission signal is issued to the busbar communication circuit breaker 12, and the auxiliary equipment group 1. Issue a shutdown command to n. Qs< QT
-QHLII-QIIL12, local bus switching is not performed.

These calculations and comparisons are performed moment by moment, and the results from the previous - cycle are always memorized. When the - unit trip signal is issued, the station bus is switched based on the memorized results, which saves time. It is possible to implement it without delay.

〔Effect of the invention〕

According to the present invention, this is made possible by constantly monitoring the actual operating load capacity, calculating and monitoring the margin of the transformer, and improving the reliability of the power supply for the in-house auxiliary equipment.

[Brief explanation of the drawing]

Fig. 1 is a single line diagram of an embodiment of the present invention, Fig. 2 is a block diagram showing the process leading to bus bar switching of the present invention, Fig. 3 is a flow chart showing the contents of bus bar switching control of the present invention, and Fig. 4 is a single line diagram of the prior art. 23.27.25...Bus voltage detector, 24,28°26...Load current detector. Figure Figure Figure T-1, 1-2 Figure 4! One hoooooo

Claims (1)

[Scope of Claims] In a power supply system that has one, three or more power supplies and each power supply bus is connected to each other by a circuit breaker, etc., the operating load capacity is constantly monitored and all possible buses are connected. Compare with the possible operating capacity of the transformer in the switching case,
An in-house bus switching control system that determines whether bus switching is possible. 2. In claim 1, if the switching of the power supply bus is rejected, the station calculates how far the load should be selectively cut off to make it possible and issues a command. Busbar switching control method. 3. In claim 1, there is provided a station bus which detects and calculates on a regular basis and stores only the latest results so that there is no time delay when a situation in which a station bus is to be switched occurs. Switching control method.