JP2713955B2 - Arc extinguishing reactor control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an isolated reactor control device arranged in a power distribution system, and more particularly to an isolated reactor control device that controls the impedance of a reactor with high accuracy.

[Conventional technology]

For the purpose and principle of the layout of the isolation reactor installed in the distribution system, refer to 3.Electrical Computation, Vol. 43, 1975, Maruta, Accidents at Distribution Substations and Concepts of Protection Relay Systems. Phenomenon (1) As described in the section on ground faults, this is to suppress this for security in a distribution line with a large ground fault current, but a method of positively changing the residual zero-sequence voltage Was not taken into account. FIG. 7 shows the generation of the residual zero-sequence voltage as an equivalent circuit as a micro-ground fault between one line and the ground. (Reference: Electrical calculation VO
L.43,1975 Tohei Author commentary 4. ground fault "work of the ground fault direction relay as viewed from the input and output") R _g is the impedance of the clear distinction finely ground絡点, 3C is system ground capacitance, L is The extinction reactor, r is the resistance of the extinction reactor, and R is the parallel resistance. In such an equivalent circuit, the residual zero-sequence voltage V ₀ can be expressed by the following equation.

And

In the above equation, r is usually several percent as compared with jωL and can be ignored, and V ₀ is , That is, when the earth capacitance of the system and the impedance of the isolated reactor become equal, the maximum value is obtained. For this reason, in the conventional isolated reactor control device, the tap of the isolated reactor is switched to change the impedance,
The magnitude of the zero-sequence voltage V ₀ was measured, and the tap of the isolated reactor having the maximum magnitude of the zero-sequence voltage was selected. However, the residual zero-sequence voltage changes depending on the system state of the distribution line, and no consideration has been given to controlling the magnitude of the residual zero-phase voltage from a control device.

[Problems to be solved by the invention]

The above prior art is a method of measuring the absolute value of the residual zero-sequence voltage, and does not consider the phase of the zero-sequence voltage.

An object of the present invention is to control the impedance of the isolated reactor by generating another zero-sequence voltage regardless of the residual zero-sequence voltage.

[Means for solving the problem]

In order to achieve the above object, the present invention is installed in a power system of an isolated reactor grounding system, and connects a predetermined impedance between at least one of three phases of the power system and a ground via a switch element, A zero-phase voltage generation circuit that changes a zero-phase voltage by opening and closing the element, a zero-phase voltage input circuit that derives a zero-phase voltage of the power system, and a power system voltage input circuit that derives a positive-phase voltage of the power system. A zero-sequence voltage generated by a zero-sequence voltage generation circuit, and a decoupling reactor control device that controls the impedance of the decoupling reactor by monitoring the phase of a positive-phase voltage derived from a power system voltage input circuit. When a zero-phase voltage is generated by the zero-phase voltage generation circuit, the first phase, which is an advanced phase with respect to the zero-phase voltage, from the positive-phase voltage detected by the power system voltage input circuit.
And a second reference voltage that is a lag phase is detected, and a product operation of the zero-phase voltage derived from the zero-phase voltage input circuit and the first and second reference voltages is performed. Deriving the first and second common-mode components that are the common-mode components of the zero-sequence voltage with respect to the second reference voltage, and controlling the impedance of the isolated reactor so that the magnitudes of the first and second common-mode components are the same. It is something to do.

[Action]

An equivalent circuit when the impedance Z is applied between a line and the ground can be expressed as shown in FIG. Now switch SW is OF
Expressed by the following equation when the zero-phase voltage when the F and V _01.

Also, when the switch SW is a zero-phase voltage when the ON and V ₀₂ can be expressed by the following equation.

When considering the magnitude of the zero-sequence voltage in the above formulas (2) and (3), from the viewpoint of protection of the power distribution system, a complete ground fault, that is, R _g
It must be about several percent of the value when = 0. This is because the setting value of the protection relay is 20 ~ with the tertiary output of the earthing transformer for the instrument.
This is because the voltage is 30 V, which is about 10 to 16%, so that it must be 10% or less in order to cooperate with the protection relay. Therefore, the values of R _g and Z are about 100 times as large as Z ₀ . From this, it is practically possible to rewrite equations (2) and (3) under the conditions of R _g ≫Z ₀ and Z≫Z ₀ , Becomes

The equation (5), the introduction of the impedance Z, the zero-phase voltage generated is a positive phase voltage to an impedance ratio between Z ₀
It can be seen that a multiplied by E _a. Since Z ₀ is a parallel circuit of L, C, and R, depending on each value, (1) R only, (2) R and L, (3) R and C Conceivable.

Impedance Z is because it is known value, relative to the E _a / Z, wherein the Z ₀ to the reference voltage (1),
The phase of the zero-sequence voltage generated when the impedance Z is applied when the values of (2) and (3) are taken is as follows.

(1) In the case of only R component: in-phase with the reference voltage (2) In the case of R and L components: leading phase with respect to the reference voltage (3) In the case of R component and C component: lagging phase with reference voltage From the state of Z ₀ , that is, whether the value of the impedance of the isolated reactor and the impedance of the ground capacitance of the system match, whether the impedance of the isolated reactor is larger than the impedance of the ground capacitance,
The determination as to whether it is small can be made by determining the phase of the zero-phase voltage generated when the impedance Z is applied.
Accordingly, the tap of the isolated reactor is switched, the impedance Z is input, the generation phase of the zero-phase voltage is determined, and when the isolated reactor and the impedance are larger than the impedance of the ground capacitance, the isolated reactor tap is used. Is switched so that the impedance becomes smaller.
The tap of the decoupling reactor is switched so that the impedance increases, the impedance Z is turned on again, the generation phase of the zero-sequence voltage is determined, and the decoupling reactor is set so that the impedance of the decoupling reactor and the impedance of the ground capacitance become equal. By controlling the tap, the object of the present invention is achieved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

An isolation reactor control device 4 is installed on the substation bus 1 in the distribution substation, and the isolated reactor load corresponding to the ground capacitance 3 of the high-voltage distribution line 2 drawn from the substation bus 1 is subjected to a zero-phase voltage. It is working to insert into. Next, the configuration and operation of the isolated reactor control device 4 will be described.
The high-voltage coupler 5 is connected to the substation bus 1, and has a zero-phase voltage 7 (v ₀ = V ₀ sin (ωt) proportional to the zero-phase voltage of the distribution system.
± α)) and the reference phase voltage 6 (v _a
= And outputs the V _a sinωt). Reference phase voltage 6 phase shift circuit A8 is (v _a = V _a sinωt) to 135 ° advances the first reference voltage And the phase shift circuit B9 outputs the reference phase voltage 6 (v _a = V _a sin ω).
The second reference voltage advanced t) by 45 degrees Is output. Zero-phase voltage generator 21, transformer T _r and is composed of a capacitor C and a switch SW, 1 transformer T _r
The secondary winding is connected between one line of the substation bus 1 and the ground, and a switch SW and a capacitor C are connected in series between the terminals of the secondary winding. A zero-phase voltage is generated in the system by turning on and off the switch SW.

According to this method, the input impedance of the zero-phase voltage generated in the system is the capacitor C. Therefore, if the impedance of the isolated reactor and the impedance of the ground capacitance become equal, and if only the resistance component is present, the positive impedance is obtained. It becomes a zero-phase voltage having a phase leading by 90 degrees with respect to the phase voltage v _a . In addition, when the impedance of the isolated reactor is larger than the impedance of the ground capacitance, the zero-phase voltage v ₀ has a lead of 90 degrees or less with respect to the positive-phase voltage v _a , and conversely, the lead has a lead of 90 degrees or more. . Thus, the zero-phase voltage 7 has a leading phase of (90 + θ) or (90−θ) degrees with respect to the positive-phase voltage, depending on the ratio of the impedance of the isolated reactor to the impedance of the ground capacitance. The zero-phase voltage 7 having such a phase relationship is a multiplier.
Connected to 10 and 11. In the multiplier 10, a phase shift circuit is further provided.
The output of A8, that is, the first reference voltage v _a1 is input, and a product operation is performed. The output of the multiplier 11, similarly the phase shift circuit B9, i.e. enter a second reference voltage v _a2, and a product operation line summer. This product operation is represented by the following equation.

Looking at each of the multiplied outputs from the above equation, each of them is the sum of the first term and the AC component of the second harmonic of the second term of the DC component. Further, the magnitude of the DC component is maximum when each reference voltage and the zero-phase voltage are in phase. From this, if the harmonic component is removed from the product calculation output and only the DC component is extracted, the magnitude of the DC voltage is compared to determine whether the phase of the zero-phase voltage 7 is the first reference voltage v _a1 side. , The second reference voltage v _a2 can be determined. That is, FIG. 3 shows the phase characteristics of the DC component output of the multiplier 10 and the DC component output of the multiplier 11.

The DC component output of the multiplier 10 advances with respect to the reference phase voltage v _a 13
The circular characteristic 14C becomes the maximum at 5 degrees, and the DC component output of the multiplier 11 becomes the circular characteristic 15C which becomes the maximum at 45 degrees. When the zero-phase voltage v ₀ advances and is 90 degrees, the DC component voltages of the multiplier 10 and the multiplier 11 are equal.
The DC divided voltage of 10 is larger, and when it is 90 degrees or less, the DC divided voltage of multiplier 11 is larger. From this, the output of the multiplier 10 is connected to the low-pass filter 12,
The first DC voltage 14 is derived and output to the comparator 16. Similarly, the output of the multiplier 11 is connected to the low-pass filter 13 to derive the second DC voltage 15 and output it to the comparator 16. In the comparator 16, the first DC voltage 14 and the second DC voltage 15 are input. When (first DC voltage 14)> (second DC voltage 15), a comparison output 17 is output. When (first DC voltage 14) <(second DC voltage 15), the comparison output 18 is output.

The control circuit 19 outputs a switch-on command 20 to the zero-phase voltage generation circuit 21 to generate a zero-phase voltage, and receives comparison outputs 17 and 18 from the comparator 16. When the comparison output 17 is output, it is determined that the impedance of the isolated reactor is smaller than the impedance of the ground capacitance, and the control output 22 is output to the switch 23 such that the impedance of the isolated reactor 24 is increased. When the comparison output 18 is output, it is determined that the impedance of the isolated reactor is larger than the impedance of the ground capacitance, and the isolated reactor is switched to the switch 23.
The control output 22 is output such that the impedance of 24 is reduced.

The grounding transformer 26 (GTR) is connected to the substation bus 1, and a parallel resistor 25 and an isolation reactor 24 are connected in parallel to the low-voltage side open delta output. Therefore, the parallel resistance 25 and the isolation reactor 24 are connected in parallel with the ground capacitance 3 as in the equivalent circuit shown in FIG.

The operation of the above configuration in which the impedance of the isolated reactor 24 is controlled by the switch 23 and is selected so as to be equal to the impedance of the ground capacitance 3 will be described with reference to FIG. In the figure, at times T1 to T2
During the period T3, the impedance of the isolated reactor is smaller than the impedance of the ground capacitance. On the other hand, the period between the times T3, T4, and T5 is large.

Figure 2 (a) is the reference phase voltage 6 (v _a), the control circuit
19, a switch-on command 20 at time T ₁ as shown in FIG. 2 (b) and "ON", to generate a zero-phase voltage 7, as indicated in the figure (c). FIG. 2D shows the output waveforms of the multiplication circuits 10 and 11, which include the second harmonic and the DC component.

FIG. 2E shows the output of the low-pass filter 12, and FIG. 2F shows the output of the low-pass filter 13. Since the generated phase of the zero-phase voltage 7 is _a lead phase larger than 90 degrees with respect to the reference phase voltage 6 (v _a ), v ₁ shown in FIG. 3 becomes the first DC output 14, and v ₂ shown in FIG. The DC output of 2 is 15. Time T1
After the zero-phase voltage 7 is generated, the low-pass filters 12 and 13
After a time t seconds until the output becomes stable, the control circuit 19 inputs the presence or absence of the comparison outputs 17 and 18, and the comparison output 17 is “present”,
The fact that the comparison output 18 is “absent” is stored. At time T2, the control circuit 19 sets the switch-on designation 20 to “OFF” to stop the generation of the zero-phase voltage, and then outputs the control output 22. Since the comparison output 17 is “present”, the control circuit 19 Increase the value. Next, after the control of the switch 23 is completed, at time T3, the control circuit 19 sets the switch-on command 20 to "ON" again to generate the zero-phase voltage 7 as shown in FIG. 2 (c). Generation phase of the zero-phase voltage 7 reference phase voltage 6 (v _a)
3 is the first DC output 14, and v4 in FIG. ₃ is the second DC output 15. Accordingly, the control circuit 19 inputs the presence or absence of the comparison outputs 17 and 18 after the time t seconds from the time T3 as described above, and
Is “absent” and the comparison output 18 is “present”. At time T4, the control circuit 19 sets the switch-on command 20 to “OFF” to stop the generation of the zero-phase voltage, outputs the control output 22, and the comparator output 18 is “present”.
Decrease the impedance of 24.

As described above, the isolated reactor control device 4 includes:
A zero-sequence voltage is generated in the system, and the isolated reactor 24
It is determined whether the impedance of the grounding capacitance is larger or smaller than the impedance of the ground capacitance, and the tap of the isolation reactor 24 is controlled so as to be equal to the impedance of the ground capacitance 3 of the system. According to the present embodiment, depending on the presence or absence of the comparison output, whether the impedance of the decoupling reactor is larger than the impedance of the ground capacitance,
Since it is possible to determine whether the tapping is small, there is an effect that tap control of the isolated reactor can be efficiently performed.

Next, another embodiment of the present invention will be described with reference to FIGS.

The difference between the decoupling reactor control device 34 and the decoupling reactor control device 4 in the above embodiment is that a low-pass filter is used.
Sample and hold circuits 27, 28 between 12, 13 and comparison circuit 16
And the subtraction circuits 30 and 31 are inserted, and the other components are the same as those of the isolated reactor control device 4. The sample and hold circuits 27 and 28 are controlled by a sample and hold command 29 from the control circuit 19, and when the sample command is issued, the input voltage is output as it is, and when the hold command is issued, the input voltage at the time when the hold command is output is output. Is output, and the operation of keeping the output as it is is performed.

The subtraction circuit 30 receives the output of the sample and hold circuit 27 and the first DC voltage 14 and subtracts (the output of the sample and hold circuit 27) from (the first DC voltage 14) as a first subtraction output 32. Output.

The subtraction circuit 31 receives the output of the sample and hold circuit 28 and the second DC voltage 15, and subtracts the (output of the sample and hold circuit 28) from (the second DC voltage 15) to obtain a second subtraction output 33. Is output as

The operation when such an isolated reactor control device 34 is used in a distribution line having a large residual zero-sequence voltage will be described. Although the generation phase of the residual zero-sequence voltage occurs in any phase between 0 degrees and 360 degrees, it is now 45 degrees from the reference phase voltage 6 (v _a ).
FIG. 6 shows a case where the first direct current voltage 1 is generated in the first phase, that is, the case where the first direct current voltage 1 is in phase with the second reference voltage (v _a2 ).
The phase characteristics of 4 and the second DC voltage 15 are shown as 14c and 15c. Since the residual zero-sequence voltage has the same phase as the second reference voltage (v _a2 ), the DC voltage v _{OFF corresponding} to the residual zero-sequence voltage is generated without generating the zero-sequence voltage in the zero-sequence voltage generation circuit 21. ing. Since the residual zero-sequence voltage has a phase difference of 90 degrees from the first reference voltage (v _a1 ), the DC component becomes zero when subtracted by the multiplication circuit 10.

In such a system, the operation when the switch input command 20 is output as shown in FIG. 5A will be described. If the impedance of the isolated reactor is smaller than the impedance of the ground capacitance during the time T1 to T2 to T3, the time T3 to T3
On the other hand, the period between T4 and T5 is large. When generating a zero-phase voltage at time T ₁ the first DC output 14 as in the fifth diagram (b), the DC voltage of the zero-phase voltage generator component v ₅ from 0V. v ₅
Is shown in the phase characteristic of FIG.

The second DC output 15 as in the fifth diagram (c), a DC voltage of v ₆ plus the zero-phase voltage generated content from v _OFF residual zero-phase voltage. v size of ₆ is shown in the phase characteristic of FIG. 6.
As with deion reactor control apparatus 4 in the previous example, if you enter this first DC voltage 14 and the second DC voltage 15 to the comparator circuit 16, v _6> v for a _5, the comparison output
18 becomes “Yes”, and the control circuit 19 determines that the impedance of the isolated reactor 24 is larger than the impedance of the ground capacitance. In fact, an erroneous determination is made that the impedance of the isolation reactor 24 is large although it is small. In order to solve such a problem, in the present embodiment, sample-and-hold circuits 27 and 28 and subtraction circuits 30 and 31 are provided.
At the same time, the sample / hold command 29 is switched from the sample command to the hold command, and the sample / hold circuit 28 holds the DC voltage v _{OFF corresponding} to the residual zero-phase voltage. In this way, the second subtraction output 33 of the subtraction circuit 31 between the times T1 and T2 becomes the zero-phase voltage generation circuit 21 as shown in FIG.
Becomes the DC voltage v ₆ ′ corresponding to the zero-sequence voltage changed. T1 ~
As shown in FIG. 5 (e), the first subtraction output 32 of the subtraction circuit 30 during T2 is the same as that shown in FIG.

By inputting the first subtraction output 32 and the second subtraction output 33 obtained as described above to the comparison circuit 16, the magnitude of the DC voltage with respect to the zero-phase voltage changed by the zero-phase voltage generation circuit 21 is obtained. Will be compared, ie, the first subtraction output 32
The next v ₅ in FIG. 6, the second subtraction output 33 of FIG. 6 (v ₆
−v _OFF = v ₆ ′, and since v ₅ > v ₆ ′, the comparison output 17
Is output and a correct judgment can be made.

At time T2, the switch input command 20 is turned "OFF", and at the same time, the sample hold command 29 is switched from the hold command to the sample command.

Time performs deion reactor 24 and tap control in between T2 to T3, the first DC voltage 14 in the case where the ON the switch-on command 20 at time T3 is v _7, the second DC voltage
15 v. _8, the second subtraction circuit 33 _{(v 8 -v OFF) = v} 8 '
Becomes

As apparent from FIG. 6, since v ₇ <v ₈ ′, the comparison output 18 is output, and it can be correctly determined that the impedance of the isolated reactor 24 is smaller than the impedance of the ground capacitance. According to the present embodiment, there is an effect that even in a distribution line having a large residual zero-sequence voltage, the impedance of the isolated reactor that matches the impedance of the ground capacitance can be selected.

Further, the fact that the impedance of the decoupling reactor can be correctly selected even when the residual zero-sequence voltage is large means that the magnitude of the zero-sequence voltage generated by the zero-sequence voltage generation circuit 21 may be reduced. Since the input impedance can be reduced, there is another effect that the device can be downsized.

〔The invention's effect〕

According to the present invention, it is possible to determine whether the impedance of the isolated reactor is larger or smaller than the impedance of the ground capacitance by one determination operation, so that the tap of the isolated reactor is changed when the distribution line system is changed. Since the control is always switched in a direction to become equal to the impedance of the ground capacitance, tap control can be efficiently performed, and there is an effect that a change in the distribution system can be quickly dealt with.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention, FIG. 2 is a waveform diagram for explaining operation, FIG. 3 is a phase characteristic diagram for explaining characteristics, and FIG. 4 is a diagram of another embodiment of the present invention. FIG. 5 is a waveform diagram illustrating operation, FIG. 6 is a phase characteristic diagram illustrating characteristics,
7 and 8 are equivalent circuit diagrams of distribution lines. 1 ... Substation bus, 2 ... High voltage distribution line, 3 ... Capacitance to ground, 4,34 ... Isolated reactor controller, 5 ... High voltage coupler, 8 ... Phase shift circuit A, 9 ... … Phase shift circuit B, 10,11…
… Multipliers, 12,13 …… Low-pass filters, 16 …… Comparison circuits, 19 …… Control circuits, 21 …… Zero-phase voltage generation circuits, 24 ……
Silent reactor, 25 ... parallel resistance, 26 ... grounding transformer,
27,28 ... Sample holder, 30,31 ... Subtraction circuit.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Eisaburo Sakami 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside the Kokubu Plant, Hitachi, Ltd. (72) Kazuo Nishijima 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1 In the Kokubu Plant of Hitachi, Ltd. (72) Inventor Yoshiki Soda 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture Inside Shikoku Electric Power Company (72) Inventor Kazuyoshi Kitaura 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture Shikoku Electric Power Company (56) References JP-A-53-25852 (JP, A)

Claims (2)

(57) [Claims] 1. A power supply system for an isolated reactor grounding system, wherein a predetermined impedance is connected between at least one of the three phases of the power system and a ground via a switch element, and the open / close state of the switch element causes zero. A zero-phase voltage generation circuit for changing a phase voltage; a zero-phase voltage input circuit for deriving a zero-phase voltage of the power system; a power system voltage input circuit for deriving a positive-phase voltage of the power system; A zero-phase voltage generated by a phase voltage generation circuit, and a decoupling reactor control device that controls the impedance of the decoupling reactor by monitoring the phase of a positive-phase voltage derived from the power system voltage input circuit. When a zero-phase voltage is generated by a zero-phase voltage generation circuit, a first reference voltage that is a phase advanced from the positive-phase voltage detected by the power system voltage input circuit with respect to the zero-phase voltage Detects the second reference voltage is a delay phase, performed product operation of said zero-phase voltage derived from the zero-phase voltage input circuit first, second reference voltage, said first
1. First and second common-mode components, which are common-mode components of the zero-sequence voltage with respect to a second reference voltage, are derived, and the disappearance is set so that the magnitudes of the first and second common-mode components are the same. An isolated reactor control device characterized by controlling the impedance of a reactor. 2. The isolated reactor control device according to claim 1, wherein when the zero-sequence voltage is changed by the zero-sequence voltage generation circuit, the first, second, and / or the second-sequence voltage changes with respect to the change in the zero-sequence voltage. A change amount of the common-mode component of the power supply, and controlling the impedance of the isolated reactor so that the change amount of the first and second common-mode components becomes the same when the zero-sequence voltage is changed. Solitary reactor control device.