JPS6077631A - 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 relates to an operation control device that fully controls the connection and disconnection of transformers connected to a power system.

[Prior art]

Recently, the power system has been showing signs of growth, but on the other hand, the demands for efficient operation have also become severe, making it difficult to operate devices with low loads or intermittent loads. I tend to avoid driving.

For this reason, a relatively heavy load may be connected to a power transmission system with low %H4 high innovation dance, but in this case, if a large magnetizing inrush current occurs when the transformer is turned on, the voltage will be turned on below the specified voltage, resulting in a low A problem occurs in which equipment equipped with a precision power supply with a voltage trip comes off.

Figure 1 shows the conventional power system and major equipment throughout the building.

In this system, when the transformer bank (1) in a no-load state is fully turned on, if the power supply impedance (10) is large, the excitation current (transient inrush current) when the transformer bank (1) is turned on is large.
A voltage drop greater than K will produce noise, and the voltage generated at the load end will normally drop. As a result, devices with built-in precision electronic circuits (CVOF for computers) that have a narrow tolerance range for power supply voltage
etc.) detects low voltage and trips, making it unusable? arise.

In the conventional configuration, the H2 voltage regulator bank [11 high and low voltage side breakers +21, +31 and the attached disconnector switch 1]
), 嬶.

G sword, 2) to switch the main circuit and the transformer tag.The tap changer (4) switches the voltage? I'm making adjustments.

A device for measurement (control) and maintenance (61?!-) was installed, and a voltage full voltage transformer @ on the high voltage side was installed, and current was introduced through a current transformer (c), and the low voltage side was also transformed. The tap changer (4) is installed in a separate control panel (Ql)k. In addition to the above-mentioned device (5), there is a panel (6) that controls the operation of the entire electrical plant, and commands for activation and deactivation of the main circuit are often issued from this panel (6).

In addition to measuring power, reactive power, etc. from the voltage and current on the high and low voltage sides of the transformer i11, the device (6) also performs electrical detection and protection for accidents inside the transformer flj by comparing all currents. Furthermore, means for detecting and protecting abnormalities such as overcurrent and overvoltage are provided. This is realized by a combination of all instruments and parts that are sufficiently marked, and it is possible to sufficiently deal with the occurrence of an accident during a steady operation state or during the same state.

Now, when the transformer (1) is completely shut down and put into operation, the low voltage side breaker (3), the disconnector cln, @? When the circuit breaker (2) on the high voltage side and the switchgear I2υ (A) are operated, an excitation inrush current flows to establish the magnetic flux of the transformer (1), causing a voltage drop due to the impedance 1101 on the power supply side. As mentioned above, the voltage on the receiving end bus (E) decreases, but normally the device +51 does not have a function to prevent such a situation.

[Summary of the invention]

The present invention aims to overcome the above-mentioned drawbacks of conventional devices, and provides an operation control device that reduces the excitation inrush current of a transformer.

[Embodiments of the invention]

A diagram explaining the principle of this proposal is shown in Figure 2. FIG. 2 (al is a transformer internal magnetic flux characteristic diagram, (1)) is an equivalent circuit diagram. When the secondary of the transformer is fully opened, the terminal (b) is released and the current 12 disappears, and when the next VC heavy pressure EL is removed, 0111 disappears, resulting in no load and no voltage electrically. however,
Magnetic flux remains in the iron core inside the transformer, and this magnetic flux sometimes reaches the same order of magnitude as the magnetic flux level when the transformer is in constant operation. This state is shown by II RI+ in FIG. 2(a).

If the magnetic flux remains in this 'R' state, the next time a voltage is applied in the positive direction (increasing direction), the iron core will be magnetized largely in the positive direction, causing a large magnetic flux change of a certain width. A magnetizing current is required.As a result, a large magnetizing inrush current is collected from all power sources.

Magnetic flux condition inside the transformer to avoid such alignment?
A circuit is installed to estimate the changes in the magnetic flux inside the transformer.

In other words, the voltage induced inside the transformer Kd dφ e −−N2− (1) t Since there is the following relationship, e1+'l of this is observable when the load side is opened, but R1, Lxrj measurement Φ can be estimated based on the value.

As is clear from equation (3), is the integrand on the right side of the above equation equal to K, which makes Φkemin? The goal is to minimize it.

That is, by observing el, 11 and calculating Φ by W, it is possible to estimate the point in time when φ becomes min.

If the transformer is opened when Φ reaches min, VC, the transformer can be stopped in a state where the residual magnetic flux is minimized.

Strictly speaking, it is impossible to fully open the single-missing side switchgear W at an appropriate time so that the residual magnetic flux becomes O, but by observing, memorizing, and reproducing the opening command time and the current cutoff situation, the switchgear-specific Time delays can be learned.

Conversely, when turning on a transformer, this relationship is also used. At what point is the minimum? I know what I have to choose.

Here, since the right side of the above equation (4) is a function in which both θl and 11 are time variables, dφ/dt (internally induced voltage) can also be estimated as a function of time.

In this case as well, the relationship between the time when the command to close the switchgear @ is fully transmitted and the time when the breaker is actually closed is as follows:
Voltage between 1 and secondary side (ex-e2)? fi
You can learn while doing it.

As described above, by determining the transformer energization and deenergization times while estimating the transformer internal magnetic flux linkage and induced voltage, the transformer power-on inrush can be minimized.

At this time, the tap changer attached to the transformer? Take advantage of N1
1N2'! It is even more effective to turn off the power by changing it so as to minimize the total change in φ. That is, it is possible to completely suppress the magnetic flux while repeating tap adjustment to maximize the tap N1 on the primary side, and a considerable effect can be expected by using the current LRT 'i.

The above is just an introduction to the magnitude of the magnetic flux, but if we consider the magnetomotive force and excitation current at the same time as the magnetic flux, 'eX = f, (
φ) Tokoro de i. It can be considered that the excitation impedance current of the Xl-1 transformer leaks, so the primary and secondary currents are
As i2, there is a relationship of 4D=i-1+i2, and it is well known that this can be obtained by differentially connecting CT secondary circuits. 1 Since this value is ff1z-0 when the load is released, it becomes 1D haze 1□, and the relationship between both the induced voltage due to the magnetomotive force inside the transformer, that is, dφ e −−N2 − t and ID − ω l must be fully observed. With KJ, it is possible to detect the pattern of instantaneous magnetic flux changes inside the transformer.

Next, we will provide a general overview of the principles of the relationship between magnetic flux change measurement and switchgear operation. An explanatory diagram is shown in FIG.

If the transformer's internal magnetic flux φ follows the entire hysteresis curve shown in Figure 3, then the most desirable hysteresis curve for the transformer will sufficiently approach the minor loop, and the magnetic flux will be turned on near O. It is about opening up.

That is, in the case of the bus on the left side of the hysteresis curve in Figure 3, φ decreases from 10 and enters the loop of I, where φl → φ2 → φ
After changing to 3, t=t becomes φ-0, and the injection is made near 3.
It is about opening up.

On the other hand, since this point cannot be controlled, it is desirable to operate the switchgear within the time when the magnetic flux further decreases from φ3 so that φ=φC approaches OVc as much as possible at the time of t-tCB, and at the time of φ-φ5. After that, the time from when a command is given to the switchgear to when the switchgear actually operates (t=tcn) is measured in advance, and the time when this operation command is given is fully adjusted, and φ-〇 is reached at exactly t-tCB. All you have to do is make it happen.

The same is true for the case where the loop ``crossed'' and φ increases ■ goes through the entire loop, so it will be omitted.

Next, the configuration of an embodiment of the present invention will be described below.

In Figure 4, (Ii + (21+ (31, υ
, (a), E, on.

6, (to), [611: are the same as those in FIG.

In the present invention, a device (5') is provided at f'i (a) of the device (6) in FIG. Note that in FIG. 4, the part corresponding to the device (5) in FIG. 1 is omitted.

In FIG. 4, (51-a)
-(51-e), (52-a) -(52-4),
(53), (54) bar55).

(56-a) and (56-b).

(51-a) to (51-e) are level converters that convert the level of the input signal to an appropriate size, and (52-
a) -(52-d) ij f formation 1c! I got the input for n, sn, current transformer □□□, 62, is this it? Converts the level of AC instantaneous value as it is. The switch (51-e) receives the position signal of the tap changer (4) and converts it into an appropriate digital circuit signal 8. Is (52-a) - (52-d) the AC instantaneous value signal of (51-a) - (51-d) above?
This is a positive/negative bipolar Zangle value hold amplifier that temporarily stores the value, and holds and resets it in response to a timing signal from the main processor unit MPU, which will be described later. (5
3) It is an i multi-blephsa, and (52-a) to (52
-e) signal to the next h/r, converter (54)
VC is added.

(54) The A/D converter converts the alternating current (instantaneous value) signal switched by the multi-brancher (53) from analog to digital, and converts it to the next main processor unit MPU.
Tell K. (55) is a device (a processor unit that controls five main functions, and is usually a commercially available 8- to 16-pit microprocessor (hereinafter referred to as MPU). Select all appropriate ones according to accuracy and speed. This MPU VCl- has an input and output register (process/D port), and can appropriately store the output of the A/D converter (54) into itself (56-a). ), (
56-b) is a level converter for output, and MPU
The output signal after being processed in (55) (breaker,
It provides the opening/closing signal of the disconnector and also performs the transfer of the number to the general monitoring operation panel of each electrical station. This includes not only the measurement and judgment results of the device (5') but also the status (normal, halted, abnormal, etc.) of the device (5').

Measure the voltage applied to the transformer i1 K and the current passing through the transformer]1) in the above configuration, take into account all the tap changer conditions, make a judgment, and calculate the change in magnetic flux inside the transformer. When the hysteresis loop is estimated to be small enough, all circuit breakers and other switchgear are activated, and the transformer is turned on and off.

Next, the operation of this embodiment will be explained.

First, the case of a transformer stop operation will be explained with reference to the flowchart in Figure 5 (al). Before starting the transformer stop operation, first fully open the low voltage side breaker (3). This will cause some voltage fluctuations. , transient changes in magnetic flux also occur, but the following operations eliminate this effect.

Next, lower the tap changer (4) and turn down the transformer (1).
) is the maximum, that is, the main magnetic flux is the minimum for the same voltage. At the same time, the circuits (51) to (56) of the device (5') estimate (measure) the change in the main magnetic flux inside the transformer (φ-1 curve),
Measure whether the hysteresis looseness of this change is equal to the minimum loop of the main magnetic flux during steady operation. Note that the details will be described later.

If this magnetic flux is within the minimum hysteresis looseness, this device (5') will issue a command to open the switchgear (2) from the entire main switchboard (electrical station integrated operation monitoring and control panel, commonly known as soil board) to the switchgear (2). An output signal is generated to provide for (2). At this time, if there is no abnormality in the switchgear +21K, the switchgear (2) performs an opening operation. Subsequently, the high voltage side is opened and the entire transformer bank Ill is completely stopped.

In addition, at this time, the outfit! (The timing for issuing a command to open the breaker [21' from 5) The internal main magnetic flux changes and the timing is set so that the breaker (2) opens just when the magnetic flux φ crosses 0.The details will be described later. do.

The above series of operations? After doing so, check that there is no main magnetic flux using the operation control device, and check that the opening operation time of the breaker is as per the preset time. 1-[Approve and make corrections if necessary.

In other words, check whether the series of main circuit device operations after fully opening the breaker (3) was performed according to the planned algorithm, check whether changes to parameter 1 settings, etc. are necessary, and make corrections as necessary. It has a so-called learning function.

Next, a supplementary explanation will be given regarding the part of PBR 7 "Measurement of φ-1 inside the transformer" in the above diagram M5 (al).

Figure 6 (a+, BL shows the 70-th point of φ-1 measurement inside the transformer. 1. Start the measurement at t=to. 101), Transformer primary and secondary pressure, current Read all and know ex, il, 82.12f (102). Next, read the tag position 14? (103), and calculate the magnetic flux φoi from this value using the formula (104). Next, count the specified counter. 105) and measure el, jl, e2,12k after a certain period of time has elapsed (106). vinegar,
In conjunction with the operation of the tap changer (4), turn it downward (
107), and calculate φ (108).

As the tag goes down, the average φ gradually decreases from φ during each cycle.

The maximum value of the residual magnetic flux determined from the excitation characteristics of the φ of each vehicle is below a certain value (for example, 0.7
) is considered to change sufficiently on the minor loop of the iron core to the main magnetic flux φr, so here
From the φ-1ox subroutine 11D, all calculations are performed when the magnetic flux becomes O (Ill). After estimating that point, confirm that the main magnetic flux is 1 inch (however, K>t) VC, which is even smaller than φr, that is, it is even more minor loose (112), and then All the devices (5') output that the conditions for opening are satisfied, and the integrated panel (6) issues a trip output of 1 word "+" to open the circuit breaker (2) (03).

Next, a CB output subroutine that determines the relationship between the change in φ and the timing of opening the circuit breaker will be explained in the flow of the φ-1 measurement described in VcL.

As shown in Figure 2, the internal magnetic flux φ is in the minor loop 1
．． If one can choose to open the main circuit of the circuit breaker at a point very close to the point in time when the horizontal axis of φ-0 crosses by tracing either of the two, the excitation inrush current can be set at a minimum of 9. Figure 7 Gekonoshiya VjT'14 Output Casa Routine Flowchart? show.

This @7 shows the breaker output subroutine 'dege, t
= tos starting point (201) i, a<t
Select after φ1, and then t. 6→−△t, to
s + 2△t.

φ(1), φ(2), φ( at tos + 3△tK
3) Estimate (estimate) (202) to (205).

Next, from these three data, identify equation (3) representing φ −j
(206) to (20B). This predicts the change in φ. Since the change in φ can be considered to be approximately sinusoidal, the equation f31 at t3 when φ=0? Please solve for rt<(tOS
[However, if it can be identified as φ−φcos (ωt+θ)+φ0]].

Next, the current time t is the breaker operation time delay t. Is it the highest point in anticipation of B, or should I choose the point 2 at which t + tCB = t9 for ε which is small enough for practical use? t≦ts-tcn-1ε1 If everything is satisfied, then I would like to order the circuit breaker to close? It is better to return to the main routine [block 13 in FIG. 6(b)] to exit the program.

Next, we will discuss the case where all the charging operations are performed. FIG. 8 shows the flowchart.

In this case, contrary to the opening operation, after turning on the circuit breaker (2), disconnector Qυ, (a), and 6th line (2) from the power supply side, lower the tap in the same way to connect the transformer to the 1 change to confirm that it is in the minimum loop, and set the timing to fully close the circuit breaker (3) at φ-0. The method is the same as described above. At this timing, the circuit breaker +31' is turned on. After the circuit breaker (3) is fully turned on and the system voltage is reduced, return the tap changer (4) to its normal position. Reviewing all the measurement results of the operating equipment is the same as in the case of disconnecting a transformer.

〔Effect of the invention〕

As described above, according to the present invention, changes in the internal magnetic flux of the transformer are instantaneously observed so as to be as loose as possible, and the magnetizing inrush current is connected to the transformer system near the 0 level. This is less likely to occur, and the voltage fluctuations in the system can be minimized. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional device, FIG. 2 is a detailed explanatory diagram of the present invention, (al is a characteristic 1, (b) is an equivalent circuit diagram, and FIG. 3 is a detailed diagram of the present invention. FIG. 4 is a block diagram of a device according to an embodiment of the present invention, and FIGS. 5 to 8 are flowcharts explaining the present invention in detail. il+...Transformer, +21, +31...breaker, I2υ, (2), 0υ. (2)...disconnector, threat, 03...transformer, (c),
(b)...Current transformer, (5) (51)...Measurement (control) maintenance equipment, (6)...Control panel. In the figure, the same numbers (8) and 8 (g) respectively indicate the same parts or the parts corresponding to the bottom. . Agent Masuo Oiwa Figure 2 Figure 3 Figure 5 Figure S Figure 6 Figure 6 (b) To the cup Figure 8 Figure 8 (0) Good

Claims (1)

[Scope of Claims] (g. In a device for connecting and disconnecting all transformers connected to the power system, when disconnecting the transformers, first release the switchgear on the load side of the transformers. a means for measuring the voltage and current of the transformer after the switchgear is released; and a means for monitoring the magnetic flux level estimated from the measured values;
A transformer comprising means for minimizing magnetic flux change by operating the high-voltage side tap of the transformer, and means for fully opening the switchgear on the power supply side when the magnetic flux level reaches 0. Operation control device. (2) In a device that connects or disconnects all transformers connected to the power system, a means for closing the switchgear on the power supply side and the disconnector on the load side of the transformer when all the transformers are turned on. , the voltage and current of the above transformer after this switchgear and disconnector are closed? a means for measuring, a means for monitoring all the magnetic flux levels estimated from the measured values, and operating all the taps on the high voltage side of the transformer to minimize the f6 flux change; A breaker on the load side? A transformer operation control device comprising: means 7 for inputting.