JPH01198218A - Detection system of exciting rush current - 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 [Industrial Field of Application] The present invention relates to an excitation inrush current detection method for a relay device in a power system.

[Conventional Technology J] As a conventional method for detecting transformer excitation inrush current, there is a document published by the Institute of Electrical Engineers of Japan on July 20, 1981 [IEEJ University Course Protective Relay Engineering J (P62... Transformer excitation inrush current Characteristics of current, P2S5...detection method)
There was a method as shown in the figure.

What is shown in Fig. 7 is the detection method of excitation current in transformer protection, (12) is the protection transformer, (
13) is a current transformer (referred to as CT) at both ends of the protected transformer;
(14) is a differential calculation means for performing differential calculation of the two OCTs (13) (generally includes an auxiliary current transformer for matching the CTs (13), an input function for differential calculation, etc., but not shown). ), (5) is the fundamental wave filter that derives the fundamental component in the differential current, (6) is the second harmonic filter that also derives the second harmonic component, and (7) is the fundamental wave filter. Compare the output of the filter (5) and the output of the second harmonic filter (6), and when the ratio of the output of the second harmonic filter (6) to the output of the fundamental wave filter (5) is above a certain level, the output is determined. (15) is the excitation inrush current detection output, T
r is a transformer and L is a load.

Moreover, FIG. 9 is a diagram showing the excitation inrush current waveform of the transformer, where the vq system voltage, I is the excitation inrush current waveform, and IL is the load current (described later).

Next, I will explain the movement in detail, but also in the above-mentioned literature @
Engineering in Figure 9! Although it is obvious that the second harmonic content is high in the differential calculation means (Fig. 9), the negative # current IL (Fig. 9) is 14)
Since only the magnetizing inrush current is derived, it is possible to carry out simple calculations. It is not only the case of the above-mentioned pressure vessel failure that is affected, but also problems that occur in deep layers of power transmission lines as shown in Fig. 10. In Figure 10 (21
) is Den! (22), (24), and (25) are unprotected power transmission lines; a load is connected to the transmission line (24); a transformer (11) is connected to the transmission current (25);
3) is a bus within the protected area to which transmission lines (22), (24), and (25) are connected, and (26) is a transmission line medical catch relay. Also, Fig. 11 is a diagram showing the impedance seen by the power transmission line protection relay, and the circle indicated by (27) is the protection range, (
28) shows the impedance zone where the load zone (29) is visible due to the excitation inrush current, and (30) shows how the impedance changes due to the superposition of the load and the excitation inrush current.C
There is.

In the power transmission line protection relay (26) as shown in Fig.
) is applied to the relay, so as shown in Fig. 11, when the magnitude of the magnetizing inrush current alone becomes large, the area (27) as shown in zone (29) As the load current increases, the line (3o) will pass over the load zone (28).
In addition, since the second harmonic is not included in the load voltage waveform L + II in Figure 9, the overall second harmonic is The content rate decreases.

Therefore, the conventional magnetizing inrush current detection method cannot detect the magnetizing inrush current, so it is necessary to wait for the magnetizing inrush current to subside and provide a delay element in the protective relay (26) to prevent the magnetizing inrush current from entering the protection range. Countermeasures such as 1 for settling are required, and there are problems such as not being able to achieve high speed, reducing protection reliability due to restrictions on setting, and complicating the circuit.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a magnetizing inrush current detection method that is not affected by load current. Further, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a magnetizing inrush current detection method that is not affected by load current and is not affected by harmonics in the event of a system failure. .

[Means for solving the problem] The magnetizing inrush current detection method according to the present invention derives a negative phase component from the three-phase current of the system, and determines the magnetizing inrush current based on the second harmonic content in the negative phase component. This is to detect. Further, the magnetizing inrush current detection method according to the present invention derives a negative phase component from the three-phase current and voltage of the system, and detects the magnetizing inrush current based on the second harmonic content in the negative phase component.・Also, the excitation inrush current detection method according to the present invention derives the negative phase fair phase components from the three-phase currents and voltages of the system, and calculates them based on the second harmonic content in the negative phase components and the positive phase components. It detects excitation inrush current.

[Operation J] In the excitation inrush current in the present invention, the influence of the load current is removed by calculating the negative phase component. Furthermore, in the magnetizing inrush current detection of the present invention, the influence of the load current is removed by calculating the negative phase component, and dynamic inrush current detection is not performed when harmonics are generated at the time of a system failure. Furthermore, in the magnetizing inrush current detection of the present invention, the influence of the load current is removed by calculating the negative phase component, and when harmonics occur during a system failure, the magnetizing inrush current is not detected by detecting the second harmonic content rate of the positive phase component. do not have.

[Example j, An embodiment of the present invention will be described below with reference to the drawings.

In Figure 1, (1) is the 3-phase transmission line of the system, and (2) is the 3-phase transmission line of the system.
C T provided in each phase, (3) is an anti-phase calculation means (generally, an input transformer etc. is provided at the 111 stage of this calculation means, but not shown), (4) is a second harmonic containing The rate detection means is composed of a fundamental wave filter (5), a second high n-wave filter (6), and a comparator (7). (
8) is the excitation inrush current detection output.

Next, the operation will be explained.

Negative phase illumination using the symmetrical coordinate method is expressed as 2=(10aIC from A+a)/3, and when a symmetrical current such as a load current flows, the negative phase current becomes 0.When excitation inrush current is superimposed Also, due to the principle of stacking,
The influence of the load current is removed, and only the negative phase component of the magnetizing inrush current can be found.

Traditionally, analog relays have been used as a negative phase calculation means for deriving negative phase components.
etc. In the digital relay, t-z + t-at-4 (here, t-2 and t-4 are equivalent to 120 degrees,
240' equivalent time) have been proposed, but the details of the calculation means are not important in the present invention, so the details will be omitted.

Here, the behavior of the second harmonic component in the excitation inrush current based on the negative phase component calculation will be described.

Figure 2 shows the magnetizing inrush current that generally occurs in transformers,
This is a case where transformer saturation occurs in phase and C phase. (Because the current wraps around to other phases, the result is as shown in Figure 2.) Figure 3 shows the relationship between the excitation inrush currents of the human phase and C phase, and the fundamental waves are at about 120°. Although there is a difference,
This is a diagram explaining that the second harmonics have a phase difference of 60''. Figure 4 shows the fundamental wave and the second harmonic troughs before and after inverse phase calculation, based on Figures 2 and 3. The vectors (a) and (b) are the fundamental wave, second harmonic, and (
c) (d) shows the deviation of the fundamental wave and second harmonic wave) /l/ after negative phase calculation.

In Figure 3, the phase difference between the human phase and C phase of the fundamental wave is 120° ahead of the C phase, but in the second harmonic, the second harmonic at the fundamental wave o' point is delayed by 90° in the human phase. , the C phase leads by 90c', and as shown in the figure (since engineering A is in the positive direction and IC is in the negative direction), the phase difference between the second harmonics is 60°, where the C phase leads. .

In Figure 4, IAI, play! is the original current of the magnetizing inrush current (
The current flowing to the other phases out of this original current is defined as rm (2) and fcI, respectively. Therefore, the phase power A measured by CT is
NijiI''I'C11IC is fAl+ than l+fC1s
Becomes ICX. This also applies to the second harmonic. Next is the inverse phase calculation, but on the A phase basis, Equation 2 = Equation A + a2
rB+aI (from IAIN Engineering CI 11'A 1 s
An example of phase shift processing after decomposition into fc I is shown in Figure 4(e)N
Shown in (d). In the second harmonic, the phase rotation speed is twice that of the fundamental wave, so a: advances by 240°, and a''
: 480' advance = 120' advance.

FIG. 4 shows that the second harmonic component is amplified with respect to the fundamental wave by anti-phase calculation processing. In an actual system, it is rare for excitation inrush current to occur only in a single phase, but in this case, it is obvious that the second harmonic content does not change even if the reverse phase calculation is performed. It is expected that the inrush current detection capability will increase.

In the above-mentioned embodiments, the behavior of a power transmission line medical capture relay has been described, but the same effect can be obtained even if it is implemented in a conventional transformer protection relay, and the target of capture is not limited.

In addition, as the second harmonic content rate detection means, is a structure composed of a fundamental wave filter and a second harmonic filter shown in the diagram?In general, the fundamental wave filter is often excluded, and the second harmonic wave filter is shown. Depending on its selectivity, other same wavenumber heads may be removed in some cases, but this does not limit the configuration of this filter.

FIG. 5 is a diagram showing another embodiment of the present invention. In FIG. 5, (1) is the three-phase transmission line of the system, (2) is the C T provided in each of the three phases, and (3) is the ff41 negative phase calculation means (
(4) is a first second harmonic combination ratio detection means, which includes a fundamental wave filter (5), a second harmonic filter (6), a comparator (consisting of 71), and (8)
is a potential transformer (referred to as PT) installed in each of the three phases,
(91) is the second negative phase calculation means (the first negative phase calculation means (
3) Similarly, the input quadrature and the like are not shown), (10) is a second second harmonic content rate detection means, which has the same configuration as the first second harmonic combination rate detection means (4). , (11) is the first
The second harmonic content detection means (4) outputs the second harmonic content detection means (4), and the second harmonic content detection means (lO) outputs the output when the second harmonic content detection means (10) is not outputting.

Next, the operation will be explained.

The negative sequence current according to the symmetric coordinate method is
aIC)/3, and when a symmetrical current such as a load current flows, the negative sequence current becomes 0. Even when excitation inrush currents are superimposed, the effect of the load current is removed due to the principle of superposition, and only the negative phase component of the excitation inrush currents can be determined.

Conventionally, as a negative phase calculation means for deriving the negative phase component, in real analog relays, I2=actual ab+, c<60°, etc. In the case of µ relays, X2=actu at+Ibt-2+ICt-4
(Here, t"-z, t-< is the time equivalent to 120', 24
0'' equivalent time) have been proposed, but since the details of the calculation means are not important in the present invention, the details will be omitted.

Here, the behavior of the second harmonic component in the excitation inrush current based on the negative phase component calculation will be described.

Figure 2 shows a cape where transformer saturation occurred in the human phase and C phase due to the excitation inrush current that generally occurs in a transformer. (Because the current wraps around the phase, the result is as shown in Figure 2.) Figure 3 shows the relationship between the excitation inrush currents of the A and C phases, and the fundamental waves have a 120° phase difference. In Although,
This is a diagram explaining that the second harmonics have a 60° phase difference. Figure 4 shows the fundamental wave and the second harmonic before and after the inverse 4H calculation, based on Figures 2 and 3. (a) and (b) are the fundamental wave, second harmonic, and
(c) (d) shows the vector of the fundamental wave and the second high N wave after the inverse phase calculation.

In the third wave, the phase difference between the A phase and C[ of the fundamental wave is 1200 ahead of the C phase, but in the second harmonic, the second high pitch wave at the fundamental wave θ''' point is 900 in the human phase. °
The C phase leads by 90°, and as shown in the figure, the phase difference between the second harmonics is 60° as the C phase leads. Become.

In FIG. 4, IAI and ICr are the original currents of the excitation inrush current (currents that do not take into account the leakage to other phases), and the currents flowing to the other phases out of these original currents are designated as AI and T, respectively. Therefore, the phase current IA measured by CT is I
AI+I'CI, or 1 stone+I'CI%IC becomes 1+I'CI.This is the same for the second harmonic.Next is the inverse phase calculation, but based on physiognomy, I2= Engineering A+
a2 engineering 9 + fi engineering C s IAI% engineering CI% I'A
Figure 4 (c
) and (d). In the second harmonic, the phase rotation speed is twice that of the fundamental wave, so a: 240' advances, and a2:
4800 advance = 1200 advance.

FIG. 4 shows that the second harmonic component is amplified with respect to the fundamental wave by anti-phase calculation processing. In an actual system, it is rare for a magnetizing inrush current to occur only in a single phase, and in this case, it is obvious that the @2 harmonic content does not change even if the negative phase operation is performed. , it can be expected that the excitation inrush current detection capability will increase.

Next is the negative phase voltage, which is also calculated by the second negative phase calculation means (91) using the same calculation method as the negative sequence current, or when the excitation inrush current flows, the negative phase power supply is actually Since the reverse phase voltage does not exist and the reverse phase voltage is generated only by the reverse phase current flowing as the excitation inrush current, a correlation with the reverse phase current is established. The relationship holds true even in the case of a system failure, but when harmonics are generated during a system failure, a high-frequency 4-wave power source is generated as an anti-phase power source, and the correlation with the above-mentioned anti-sequence current breaks down, resulting in large distortion. It becomes a wave. Therefore, in a system where harmonics are generated at the time of failure, when the second harmonic content rate in the negative phase voltage is greater than a predetermined value, the second second harmonic wave combination ratio detection means (lO) outputs an output. In this case, the excitation inrush current detection is locked by the AND means (11) K.

In the above examples, the behavior of a power transmission line protection relay has been described, but the same effect can be obtained even if it is implemented in a conventional transformer floor relay, and the object to be protected is not limited.

In addition, although the illustration shows a configuration using a fundamental wave filter and a second harmonic filter as the second harmonic content rate production means, generally speaking, the fundamental wave filter is often excluded, and the second harmonic Depending on the selectivity of the filter, the filter frequency WjR may be reduced by 1, but this is not a limitation on the present filter configuration.

Next, a further embodiment of the present invention will be described with reference to FIG. 6. In Figure 6, (1) is the three-phase transmission line of the system, (2
) is the C T provided in each of the three phases, (3) is the negative phase calculation means (generally, an input transformer or the like is provided in front of this calculation means, but it is not shown), and (4) is the first, second, and The harmonic content* detection means consists of a fundamental wave filter (58, 2nd harmonic filter (6), and a comparator (7). Also, (8) is provided in each of the three phases. The instrument transformer (referred to as FT), (92) is a positive phase calculation means (negative phase calculation means (3)
Similarly, (10) is the 20th
The second harmonic content rate detection means has the same configuration as the first second harmonic content rate detection means (4), and (11) is the output of the first second harmonic content rate detection means (4). This is an AND means that outputs when the second second harmonic content rate detection means (10) is not outputting.

Next, the operation will be explained.

The negative sequence current according to the symmetric coordinate method is
aIC)/3, and the symmetrical current such as load current flows n
When this happens, the negative sequence current becomes O. Even when excitation inrush currents are superimposed, the effect of the load current is removed due to the principle of superposition, and only the negative phase component of the excitation inrush currents can be determined.

Conventionally, as a negative phase calculation means for deriving the negative phase component, in analog relays, e < 60° from work 2 = work ab +, etc. For phase p relays, work 2; from work at +, j - 2 + work at -
4 (here, t-2 and t-4 are times equivalent to 120°, 240
Although various proposals have been made, such as (indicating the equivalent time), the present invention does not care about the details of the calculation means, so the details will be omitted.

Here, the behavior of the second harmonic component in the excitation inrush current based on the negative phase component calculation will be described.

FIG. 2 shows the excitation inrush current that generally occurs in transformers, and shows a case where transformer saturation occurs in the human phase and C phase. (The current loops around to the other A41, so the result is as shown in Figure 2.) Figure 3 shows the relationship between the excitation inrush currents of the human phase and C phase, and the fundamental waves are about 1000. Although it is a phase difference, it is a figure explaining that it becomes a 60' phase difference in a second high crystal wave comrade. Based on Figures 2 and 3, Figure 4 shows the fundamental wave and second harmonic (40 peks each) A/ before and after the negative phase calculation, and (a) and (b) are before the negative phase calculation. The fundamental wave, @2nd harmonic, (c) (d) Id shows the vector of the fundamental wave and 2nd harmonic after inverse phase calculation.

In Figure 3, the phase difference between the human phase and C phase of the fundamental wave is 120° ahead of the C phase, but in the second harmonic, the second high word wave at the 00 point of the fundamental wave is delayed by 90° in the A phase. , in the C phase, the lead is 90° (because in Fig. 2, the engineering A is in the positive direction and Ic is in the negative direction)
The phase difference between the harmonics becomes 60' as the C phase advances.

In FIG. 4, AI%IC1 is the original current of the excitation inrush current (a current that does not take into account the leakage to other phases), and the current flowing to the other phases of this original current is respectively fArs■'cX. Therefore, the pope measured by CT is a construction ＾ ■ Ten construction εi, and more than I δ δ δ! , IC is engineering ^I
+ Engineering CI. This also applies to the second harmonic. Next is the inverse phase calculation, based on human physiognomy, I2 = engineering A 10a
From 2 + a engineering C, engineering AE, engineering Crs engineering AixICi
Figure 4 (c) (d) shows an example of phase shift processing after decomposition into K
It shows. In the second harmonic, the phase rotation speed is twice that of the fundamental wave, so a: 240' advance, a'': 480'
Lead = 120' lead (0) Figure 4 shows that the second harmonic component is amplified with respect to the fundamental wave by the anti-phase arithmetic processing. In an actual system, it is rare for an excitation inrush current to occur only in a single phase, but in this case, it is obvious that the second harmonic content does not change even if the reverse phase calculation is performed. It is expected that the inrush current detection capability will increase.

Next is the positive phase voltage, which is also calculated by the positive phase calculation means (9) using a known calculation method similar to the negative sequence current, but as shown in Figure 5, the inrush current flows in the transformer. Also, with respect to the power supply voltage E, only a voltage drop and voltage distortion occur at the back impedance ZxB, and the distortion ratio is very small. In addition, when a system failure occurs and voltage distortion occurs, voltage distortion occurs due to the forward impedance ZIF and the distorted wave fault current, and the distortion is large compared to the current distortion rate. From the output of the means (92), the second height al
When the wave content rate is detected by the second harmonic content rate detection means (10) to be equal to or higher than a predetermined value, the AND means (11) makes a determination so as not to determine that it is an excitation inrush current.

In the above-mentioned embodiment, the behavior of a power transmission line protection relay has been described, but the same effect can be obtained even if it is implemented with a conventional transformer protection relay, and the object to be protected is not limited.

In addition, although a configuration using a fundamental number filter and a second harmonic filter is illustrated as the second harmonic content detection means, the fundamental wave filter is generally excluded in many cases, and the second harmonic filter is In some cases, other frequency ranges may be removed depending on the selectivity of the filter, but this does not limit the configuration of this filter. Since the negative-phase calculation means is applied to current detection, the influence of the load current can be removed, the detection capability is increased, the device can be used as a cheap image, and high accuracy can be obtained. In addition, according to the present invention, the result of the negative phase calculation means is applied to the detection of the excitation inrush current, and the detection is locked by the second harmonic content in the negative phase voltage, thereby eliminating the influence of the load current. In addition to this, it also has the effect of being resistant to system distortion, increasing detection ability, making the device safer, and achieving higher accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the magnetizing inrush current detection method of the present invention, FIG. 2 is a waveform diagram showing a general magnetizing inrush current waveform, and FIG. 3 is a waveform diagram showing the second harmonic of the magnetizing inrush current waveform. A waveform diagram explaining the phase difference, Figure 4 is the second wave of the excitation inrush current wave.
Figure 5 is a block diagram showing another embodiment of the present invention. Fig. 6 is a block diagram showing another embodiment of this invention, Fig. 7 is an explanatory diagram of the symmetric coordinate method, Fig. 8 is a block diagram showing a conventional excitation inrush current detection method, and Fig. 9 is a voltage , a waveform diagram showing the excitation inrush current and the load current, FIG. IO is a connection diagram showing the power transmission line floor section, and FIG. In the figure, (1) is the power transmission line, (2) is the CT, (3
) is the first negative phase calculation means, (4) is the (first) second high chest wave containing* detection means, (91) is the second negative phase calculation means, (
92) is a positive phase calculation means, (lO) is a (second) second harmonic content detection means, and (11) is a logical product means. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) Negative phase calculation means for calculating the negative phase component of the symmetric coordinate method from the three-phase current of the system, and calculating the second harmonic content from the output of this negative phase calculation means and determining whether it is equal to or higher than a predetermined value. An excitation inrush current detection method equipped with a second harmonic content detection means. (2) A first negative phase calculation means that calculates the negative phase component of the target coordinate method from the three-phase current of the system, and a second negative phase calculation device that calculates the negative phase component of the target coordinate method from the three-phase voltage of the system. , first and second second harmonic content detection means for calculating a second harmonic content from the outputs of the first and second negative phase calculation means and determining whether the second harmonic content is equal to or higher than a predetermined value; An excitation inrush current detection method comprising an AND means that outputs an output when the first second harmonic content detection means outputs an output and the second second harmonic content detection means does not output. (3) Negative phase calculation means for calculating the negative phase component of the target coordinate method from the three-phase current of the system; positive phase calculation means for calculating the positive phase component of the target coordinate method from the three-phase voltage of the system; first and second second harmonic content detection means for calculating a second harmonic content from the output of the phase calculation means and determining whether the second harmonic content is equal to or higher than a predetermined value; and the first second harmonic content An excitation inrush current detection method comprising an AND means that outputs an output when the detection means outputs an output and the second harmonic content rate detection means does not output an output.