JPS60128829A - Transformer operation controller - 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] Technical Field of the Invention The present invention controls the number of transformers in spot network power receiving equipment in accordance with the load capacity, thereby enabling highly efficient operation with the optimum capacity of the transformers. This invention relates to a transformer operation control device.

[Technical background of the invention and its problems] Spot network power receiving equipment is an equipment that has become popular in recent years, mainly as power receiving equipment for buildings with low-voltage concentrated loads. As shown in Fig. 1, this equipment usually receives power from a substation sending breaker 1 through at least three distribution lines, connecting each power receiving point to network transformers (hereinafter referred to as transformers) 3-1 to 3-. Only the power receiving disconnector 2 is installed between 3,
On the secondary side of the transformers 3-1 to 3-3, a network protector FlQ consisting of a protector fuse 4, a protector breaker 5, and a network relay (not shown) for controlling this is installed for each transformer, and its load is The sides are connected in parallel with one network, which is the main line, through the work bus 6, and the tick-off breaker 7 is connected from the work bus 6 to this network 1. Power is supplied to each load through a tick-off fuse 8.

Now, the feature of this equipment is that by controlling the protector circuit breaker 5, the function of a network relay (not shown) automatically disconnects the failed power supply line and transformer and reconnects it when the failure is recovered. . In other words, the network relay has the following functions: (a) Reverse power cutoff;
(+1> It has three operating functions: no-voltage input, and (C) differential voltage input.In this case, even if one transformer is removed due to line failure, the load can be covered by the remaining transformers. By selecting an allowable overload capacity φ of the transformer 11, which is generally 130% of the rated output, highly reliable and stable power can be supplied.

As mentioned above, when the load capacity of spot network power receiving equipment increases, all the transformers operate using the differential voltage input function of the work relay to network 1, stably supplying high-quality power, and improving reliability. In order to achieve this, all transformers continue to operate in parallel, regardless of whether the load capacity increases or decreases. Therefore, in the conventional spot network power receiving equipment, highly efficient operation is not achieved with the optimum capacity of the transformer commensurate with the load capacity.

LObject of the invention] The present invention was made in consideration of the above circumstances, and
The purpose is to provide a transformer operation control device that can perform highly efficient operation with the optimal capacity of the transformer commensurate with the load capacity in spot network power receiving equipment.

[Summary of the invention] In order to achieve the above object, the present invention samples the load current of the operating transformer at regular intervals in the spot network power receiving equipment described above, and for each sampling □ load prediction means for predicting and calculating the load N flow at the next sampling time based on the rate of change;
A storage means for sequentially updating and storing the predicted value at the time of the previous sampling predicted by the load predicting means, and a load determining means for determining the magnitude relationship of whether the value predicted by the load predicting means is greater than or equal to a set value. As a result of the judgment by this load judgment means, if the predicted value is greater than or equal to the set value and the predicted value at the time of the previous sampling stored in the storage means is also greater than or equal to the set value, then the transformation scheduled to be operated next is determined. A standby transformer operation command means for giving an operation command to the transformer, and a means for determining the load factor of the transformer from the load current when multiple transformers are in operation, and confirming that this load factor is less than a predetermined value. Operating transformer stop command means that issues a stop command to a transformer that matches the load reduction to the conditions, and the transformer is operated according to the operation command or stop command from the iIm transformer operation command means or the operating transformer stop command means. Alternatively, by providing a transformer operation control means for supplying a control signal to the protector breaker to stop the transformer, the load condition of the transformer can be predicted in advance and the transformer operation can be performed in accordance with the load capacity. It is characterized by what it did.

[Embodiments of the Invention] First, the concept of the present invention will be described. Now, if you want to operate one transformer at maximum efficiency, the rated capacity of the transformer -
Let Po be the no-load loss, Pl be the no-load loss, and pc be the load loss.The maximum efficiency is achieved when the no-load J#iPi and the load loss Pc are equal. If it becomes possible to supply the power with two transformers, for example, a stop command is issued to the transformer 3-1 described above, and the transformers 3-2 and 3-3 are allowed to continue operating. If the load factor further decreases, for example, a stop command is also issued to transformer 3-2, causing only transformer 3-3 to continue operating.

Also, when two transformers with the same characteristics are operating in parallel,
In order to reduce losses and perform highly efficient operation, if the following conditions are met,
If one transformer supplies the load, the transformer can be operated more efficiently. Similarly, when three transformers are operating in parallel,
Load capacity P3 and 3-sub...(6) If it is below, the transformer can be operated more efficiently if the load is supplied by two transformers. However, in this case, the load power factor is assumed to be constant. As described above, high efficiency operation is possible by controlling the optimal number of transformers in accordance with the load capacity.

An embodiment of the present invention based on the above concept will be described below. FIG. 2 shows a functional block diagram of a configuration example of a transformer operation control device according to the present invention, and the same parts as in FIG. 1 are denoted by the same reference numerals.

As shown in Figure 2, this device samples the load current of the operating transformer detected by the current transformer 9 at regular intervals, and for each sampling, the rate of change from the previous sampling value is used to determine the next sampling value. A load prediction means 1O that predicts and calculates the load current, and a load judgment means 11 that determines whether the value predicted by the load prediction means 1O is greater than or equal to the load factor setting value (formula (2)) described above. , the transformer is scheduled to be operated next based on a predetermined operation schedule, provided that the predicted value as a result of the judgment by the load judgment means 11 is equal to or greater than the set value, and the predicted value at the previous sampling was also equal to or greater than the set value. The standby transformer operation command means 12 gives an operation command to the transformer, and when operating a plurality of transformers, the load factor of the transformer is determined from the load current of the transformer ((41, [6)
(Formula), if this load factor is less than a predetermined value, an operating transformer stop command means 13 gives a stop command to the transformer commensurate with the load reduction, and means for issuing the standby transformer operation command and the operating transformer stop command. Transformer operation control means 1 for providing a control signal to the protector breaker 5 for operating or stopping the transformer in response to operation or stop commands from 12 and 13;
4, and a register 15 as a storage means for sequentially updating and storing predicted values at the time of previous sampling described below.

Next, the operation of such a transformer operation control device will be described. First, the load prediction means 1O performs predictive load calculation based on the load current of the transformer 3-1 in operation. An example is shown in FIG. The current I in the figure is the transformer load current and is a function of time 1 (t ).

■8 is the transformer rated current 1SET is the set value.

[ is the current time, ti is the sampling time 61 seconds before the current time, and t2 is the sampling time 61 seconds after the current time. That is, the predicted current 12 at time [2] in the figure is calculated by the following equation using the current current I and the current change ΔI at a sampling time ΔT that goes back a certain time.

Then, the load determining means 11 determines whether the predicted current value calculated by the load predicting means 10 is greater than or equal to a preset value. FIG. 3 shows the possibility that the predicted load current value of transformer 3-1 will increase beyond the set value.

On the other hand, the criterion for outputting an operation command to the transformer scheduled to be operated next is that the predicted value at the previous sampling is greater than or equal to the set value determined by equation (2), and the standby transformer operation command is A determination is made in means 12. Here, the sampling time ΔT is determined by the system including the transformer. As a result of the above judgment, when the judgment standard is determined by the f2) range in advance, the transformer operation control means 1
4 to the transformer 3-2 that is scheduled to be operated next, an operation command is given in combination with the differential voltage application function of the network relay described above, and the transformers 3-1 and 3-2 are operated in parallel 10-. Note that in the case of only a network relay, a closing command is issued to the transformers 3-2, 3-3 at the same time by the differential voltage closing function, but in this system, the closing commands for the transformers are sequentially issued.

Next, during the parallel operation, the load factor of the transformer is shut down in the operating transformer stop command means 13 according to equation (4), and the load factor is increased until one of the transformers 3-1 or 3-2 can supply the load. When the voltage drops, the transformer 3-2 continues to operate to supply the base load, and the transformer 3-1, which has been operating until now, trips the protector breaker 5, so the supply to the load is stopped. Since the transformer primary side disconnector 2 is closed, the no-load loss is consumed. On the other hand, the load increases (4)
When a preset judgment criterion determined by a formula is met, the transformer operation control means 14 gives an operation command to the transformer 3-3 in combination with the differential voltage application function of the network relay, and the three transformers are switched on. Parallel operation is performed using the equipment 3-1, 3-2, and 3-3.

FIG. 4 is a flowchart showing the flow of the above operation, and this calculation is executed by each means shown in FIG. The operating status limit check is performed using the load current, and the overcurrent limit check is performed using the current load current as a reference.
This is done by predicting the load current in seconds. That is, it is determined whether the load current after 61 seconds is on an increasing trend. As a result, if there is a possibility that the load current I exceeds the set value,
Next, an operation command is given to the transformer 3-2 scheduled to be operated in combination with a network relay.

Next, calculate the load factor of transformers 3-1 and 3-2 that are operating in parallel, and when the load factor decreases to the point where one transformer can supply the load, continue operating transformer 3-2. is supplied to the load, and the transformer 3-1 is stopped.

On the other hand, if there is a possibility that the load will increase and exceed the set value, an operation command is given to the transformer 3-3 that is scheduled to be operated next in combination with the network relay function, and the three transformers 3-3
-1.3-2.3-3 Perform parallel operation. In addition, the load factor is monitored during parallel operation, and if the two transformers can supply power, the first operating transformer is stopped. The subsequent operation is the same as in the case of the two transformers described above. Here, the reason why the preceding transformer is stopped as the load factor decreases is to improve the reliability of transformer operation by making the operating time of each transformer uniform.

As described above, according to the transformer operation control I device of the present invention,
In spot network power receiving equipment, for multiple (3) transformers that can share the load with each other and are operating in parallel, the system predicts the load status of the operating transformers and calculates the load factor to match the load capacity. Since the number of transformers is controlled, highly efficient operation can be performed with the optimum capacity of the transformers commensurate with the load capacity.

In addition, in the above, the start of operation of the transformer scheduled to be operated next is as follows:
Based on the premise of performing cooperative operation with the preceding transformer, this transformer operation control device can be set even when the preceding transformer exceeds a certain load factor.

In addition, from the perspective of stable power supply specific to spot network power receiving equipment, the number of transformers (n) + 1 that corresponds to the load capacity is
It is also possible to control the units, that is, n+1 units, by switching the operation mode.

13- [Effects of the Invention] As explained above, according to the present invention, spot network]
In work power receiving equipment, it is possible to provide an extremely reliable transformer operation control device that can perform highly efficient operation with the optimal capacity of the transformer commensurate with the load capacity.

[Brief explanation of drawings]

FIG. 1 is a single-line diagram showing subo-1 network power receiving equipment, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a diagram for explaining an example of predicted load calculation according to the present invention. FIG. 4 is a flow chart diagram showing the operation according to the present invention. 1... substation sending breaker, 1A... power transmission line,
2... Power receiving disconnector, 3-1 to 3-3... Transformer, 4
...Protector fuse, 5...Protector breaker, 6...Network busbar, 7...Tick-off breaker, 8...Tick-off fuse, 9...Current transformer, 10...Load Prediction means, 11... load determination means,
12... Standby transformer operation command means, 13... Operating transformer stop command means, 14... Transformer operation control means, 1
5...Memory means. 14-

Claims (1)

[Claims] Power is received from the power supply substation through at least three distribution lines, a new power receiving switch is installed between each power receiving point and the network transformer, and a protector fuse, a protector breaker, and the like are installed on the secondary side of the transformer. In spot network power receiving equipment that supplies power to the load by installing a work protector on network 1 consisting of the network relay to be controlled and connecting the load side in parallel with the network bus bar, the load current of the operating transformer is controlled at regular intervals. A load prediction means for predicting the load current at the next sampling time based on the rate of change from the previous sampling value for each sampling, and sequentially updating the pre-1lli1 at the previous sampling time predicted by the load prediction means. storage means for storing the predicted value; load determining means for determining the magnitude relationship of whether the value predicted by the load predicting means is greater than or equal to a set value; and as a result of the determination by the load determining means, the predicted value is the set value. With the above, and on the condition that the predicted value at the time of the previous sampling stored in the storage means is also equal to or higher than the set value, standby transformer operation command means gives an operation command to the transformer scheduled to be operated next; When the transformer is in operation, the load factor of the transformer is calculated from the load current, and on the condition that this negative side factor is less than the expected value, a stop command is given to the transformer corresponding to the load reduction. a command means, and a transformer operation control means for supplying a control signal to the protector breaker to operate or stop the transformer in response to an operation command or a stop command from the standby transformer operation command means or the operating transformer stop command means; A transformer operation control device characterized by comprising: