JPH0224101B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a method for detecting the distribution that exists between a healthy phase or a healthy line and a faulty phase even if the breakers at both ends are opened in the event of a ground fault in a high-voltage power transmission line. The present invention relates to a secondary arc extinguishing device for a power system that extinguishes an arc current flowing through a capacitance (hereinafter referred to as a secondary arc) in a short time to shorten the reclosing no-voltage time.

[Technical background of the invention and its problems]

Generally, high-voltage, large-capacity power transmission lines employ multiconductor power transmission lines that have a large distributed capacitance between phases or lines. If a flash fault occurs in the transmission line insulator or the like due to lightning damage on such a transmission line, the distribution that exists between the healthy phase or the healthy line and the faulty phase will occur even if the shields and disconnectors at both ends of the transmission line are opened. Since induced current and induced voltage are supplied through the capacitance, arc current continues to flow through the insulator for a while, and the fault condition is not removed.

Fig. 1 is a power transmission system diagram showing such a state, where 1 is a power transmission line, 2A and 2B are power station busbars connected to both ends of the power line 1 via a disconnector CB, and C
is the distributed capacitance that exists between the faulty phase and the healthy phase of the transmission line 1, and I _F is the secondary that flows through this distributed capacitance from the healthy phase to the fault point F by receiving an induced current (arrow in the diagram). It is an arc.

Therefore, when such a secondary arc occurs in a power transmission line insulator, etc., this arc will not be extinguished for a while as described above, so when performing single-phase or multi-phase reclosing, there is no reclosing. Sufficient voltage time cannot be obtained, which poses problems in terms of system stability. This tendency becomes more pronounced in high-voltage, large-capacity transmission lines where the distributed capacitance between lines is large. For this reason, in the future
In order to realize a UHV (ultra high voltage) transmission line system, active measures to extinguish secondary arcs are required.

Recently, the second method of extinguishing the secondary arc has been developed.
There is a plan to deal with this problem by using a fixed reactor device with zero-phase compensation as shown in the figure. In FIG. 2, 3 is a line impedance consisting of a distributed capacitance 4 existing between each phase line of the power transmission line 1 and the ground, a distributed capacitance 5 existing between each phase line, and line inductance 6, and Reference numeral 7 denotes an arc-extinguishing reactor device connected to the line inlet of the electric station, and this arc-extinguishing reactor device 7 connects one end of the reactors L ₁ , L ₂ , L ₃ to each phase line of the power transmission line 1, and connects the other end to each phase line of the power transmission line 1. are connected in common, and a neutral point reactor L _g is connected between the common connection and the ground.

Here, the arc extinguishing function of the arc extinguishing reactor device will be explained as follows. That is, power transmission line 1
The admittance matrix determined by the distributed capacitance of is expressed by equation (1).

Y _C = Y _C11 −Y _C21 −Y _C31 −Y _C12 Y _C22 −Y _C32 −Y _C13 −Y _C23 Y _C33 …(1) Also, the admittance matrix of the arc-extinguishing reactor device is as shown in equation (2). is expressed in

Y _L = Y _L11 −Y _L21 −Y _L31 −Y _L12 Y _L22 −Y _L32 −Y _L13 −Y _L23 Y _L33 …(2) Therefore, the total admittance of transmission line 1 is as follows (3)
The formula becomes

Y=Y _C +Y _L …(3) Since the admittance matrices Y _C and Y _L shown in equations (1) and (2) above have different characteristics, Y _L
By appropriately selecting the value of , it is possible to make the mutual admittance zero, that is, the distributed capacitance between the lines zero. This makes it possible to extinguish the secondary arc.

On the other hand, with the arc-extinguishing reactor device having the above configuration, it is not possible to reduce electrostatic induction from a healthy line to zero in the case of parallel power transmission lines. Therefore, in such a case, an arc-extinguishing reactor device having a configuration as shown in FIG. 3 is being considered. That is, in FIG. 3, one end of reactors L ₁ , L ₂ , L ₃ is connected to each phase line of power transmission line 1 of one line, and one end of reactors L ₄ , L ₅ , L ₆ is connected to the transmission line of another line. Connect each phase line of the electric wire 1, connect the other ends of these reactors L ₁ to _{L 6} in common, and connect a neutral point reactor L _g between the common connection part and the ground to create an arc extinguishing reactor. It constitutes a device 8.

Here, the arc extinguishing function of the arc extinguishing reactor device having the above configuration can be explained in the same manner as described above. That is, the admittance matrix determined by the distributed capacitance of the two-circuit power transmission lines 1, 1 is expressed by equation (4).

Further, the admittance matrix of the arc-extinguishing reactor device 8 is expressed by equation (5).

Therefore, the total admittance of the two-circuit power transmission lines 1, 1 is expressed in the same manner as the above equation (3), and by appropriately selecting the value of Y _L , it is possible to extinguish the secondary arc.

By the way, when selecting the value of admittance Y _L in the arc-extinguishing reactor device as described above, it is necessary to set the value of Y _{L to a constant value determined by the admittance due to the distributed capacitance of the power transmission line, or to set the value of Y L} to a constant value determined by the admittance due to the distributed capacitance of the power transmission line, or to set the value of Y L to a constant value determined by the admittance due to the distributed capacitance of the power transmission line. A method is being considered in which the value is set to a certain calculated value upon determination.

However, the admittance due to the distributed capacitance of the power transmission line changes depending on the faulty phase, and it is inevitable that the calculation of the line constant, which is the standard for setting the optimal admittance Y _L by calculation, includes a considerable error. Furthermore, the value of Y _L is not necessarily the optimal value depending on weather conditions. For this reason, it is difficult to extinguish the secondary arc within a short time, and Y _L
The value of is sometimes changed to a value above or below the optimum value, but since this only scans within the determined upper and lower ranges, under the worst conditions, the arc extinguishing time may become considerably long. Furthermore, it may become difficult to extinguish the secondary arc.

[Purpose of the invention]

An object of the present invention is to provide a secondary arc extinguishing device for a power system capable of extinguishing a secondary arc within a short time by compensating for the error in the optimum admittance Y _L resulting from the above calculation. .

[Summary of the invention]

In order to achieve the above object, the present invention changes the reactance of the phase reactor around the optimum reactance value calculated for each faulty phase using the secondary arc voltage and the neutral point reactor current as feedback elements. be.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 shows an example of the basic configuration of the present invention. In Figure 4, LINE is the power transmission line connected via the power station bus line BUS and the disconnector CB.
Here, each phase line of one circuit of the two-circuit power transmission line is shown as a single connection. L ₁ to _{L 6} are thyristors installed on each phase line of the two-circuit transmission line at the line entrance of the electric station.
Each phase reactor is connected in a star shape through THY in series, and a neutral point reactor L _g is connected between the neutral point and the ground. Each phase reactor L ₁ ~ L ₆
The reactance (admittance) of the thyristor THY is continuously varied by controlling the firing angle of the thyristor THY. On the other hand, PRO is a power transmission line
This is a protection relay that receives current from current transformer CT ₁ installed on LINE and voltage from instrument transformer PD ₁ connected to bus bar BUS. This protection relay PRO operates when a transmission line fault is detected. death,
It sends a trip signal TP to the shield breaker CB. CONT is started when it receives the operating output of the protective relay PRO, and voltage is applied from the instrument transformer PD ₂ connected to the power transmission line _LINE . This firing angle control device CONT receives current from each current transformer CT ₂ .
When started by the operation output of the protective relay PRO, converts the voltage and current signals input from the potential transformer PD ₂ and the current transformer CT ₂ into a DC level, judges this level value, and controls the thyristor THY. The firing angle is controlled by applying a gate control signal GC to the gate.

Figure 5 shows the internal configuration of the firing angle control device CONT, in which the PHC receives the operational output of the protective relay PRO as a starting command, as well as the output of the instrument transformer PD ₂ and the output of the current transformer CT ₂ . is analog/
This is an ignition phase comparison controller input through the digital converter A/D, and this phase comparison controller
The PHC consists of a discrimination device that has a built-in storage device such as a CPU. PC is ignition phase comparison controller
A phase control circuit to which the output obtained through the digital/analog converter D/A in the output stage of the PHC is added, and PG is a pulse to which the output αS of this phase control circuit PC is added and provides a gate signal GS to the thyristor THY. It is an oscillator. Incidentally, the ignition phase comparison controller PHC is configured to feed back its output as a level feedback signal LF.

Next, the operation of the secondary arc extinguishing device for the power system constructed as described above will be described. Now, when a failure occurs in the power transmission line LINE in Figure 4, the transmission line protection relay PRO detects the failure occurrence, failure phase, and failure type, and this is detected by the firing angle control device shown in Figure 5.
Provided as a digital signal to CONT's ignition phase comparison controller PHC. This ignition phase comparison controller
The PHC uses a phase control circuit PC so that the reactance of each phase is calculated in advance according to the faulty phase.
Add analog output to each. phase control circuit
In the PC, the level of the analog quantity is determined by the firing angle α ₁ of each phase,
α ₂ ...convert to a voltage level commensurate with α ₆ and give this to the pulse oscillator PG. In the pulse oscillator PG, the gate control signal necessary for firing the thyristor is sent to the thyristor of each phase at the firing angle α ₁ , α ₂ ... α ₆ of each phase.
The reactance value of each phase reactor L ₁ to _{L 6} is first controlled to the optimum calculated value for extinguishing the secondary arc. At this time, as mentioned above, the secondary arc may not be extinguished due to errors in determining the transmission line constants and weather conditions, so the arc voltage is determined by the potential transformer PD ₂ connected to the transmission line LINE. is detected and converted into analog/digital converter A/
D and as a high-speed analog signal, e.g.
Firing angle phase comparator with judgment device such as CPU
Send to PHC. On the other hand, the neutral point reactor current detected by the current transformer CT ₂ installed on the neutral point reactor L _g side is passed through the analog/digital converter A/D as a high-speed analog signal for firing angle phase comparison control. Send to PHC.

Here, when both the arc voltage detection signal and the neutral point reactor current detection signal are input to the firing angle phase comparator PHC, the firing angle phase controller PHC
control is performed to send out an output at a level lower (or higher) than the previously output analog level.
Then, the analog quantity output from the digital/analog converter D/A is converted into firing angles α ₁ ±Δα ₁ , α ₂ ±Δα ₂ , ... α ₆ ±Δα ₆ of each phase by the phase control circuit PC, and the pulse By controlling the gate of the thyristor PHY of each phase with the oscillator PG,
The reactance values of L ₁ to _{L 6} each change by a value ΔL commensurate with the change in the transmission line constant. This causes the secondary arc voltage to change by ΔV.

In this case, the input arc voltage level and reactor current are stored in the storage device of the firing angle phase comparison controller PHC, which has a determining device such as a CPU.

When the reactance values of reactors _L1 to _L6 of each phase change by ΔL, the new arc voltage level input to the analog/digital converter A/D is compared with the previous voltage level, and the voltage level is determined to be lower. If it is, the firing angle phase comparison controller
The PHC outputs an analog level signal lower (or higher) than the digital/analog converter D/A.

Conversely, if the new arc voltage level is higher than the previous arc voltage level, the firing angle phase comparison controller PHC will output an analog level signal that is ΔV higher (or lower) than the previous analog level. Ru. Then, the reactance value of each phase reactor L ₁ to L ₆ is changed by ΔL.

While repeating this process to minimize the secondary arc voltage and comparing it with the arc voltage before changing the firing angle, calculate the reactance (admittance) value of the reactors L ₁ to _{L 6} of each phase. Let's change it. When the secondary arc voltage eventually reaches zero or the minimum value, this arc voltage changes greatly and the current level of the neutral point reactor L _g becomes zero. As a result, the secondary arc is extinguished, and the power transmission line can be reinserted.

The above-mentioned action can be expressed as a flowchart as shown in FIG.

In addition, in the above explanation, the secondary arc extinguishing device is installed separately, but in recent years, in high-voltage power transmission lines, in order to stabilize power transmission, the above-mentioned If the ignition angle phase control function is provided, the reactor of the reactive power compensator can be used as it is as a secondary arc extinguishing device.

[Effects of the Invention] As described above, according to the present invention, in a high-voltage, large-capacity two-circuit transmission line, the admittance due to the distributed capacitance of the transmission line changes depending on the fault phase, and the optimum admittance can be set by calculation. It is possible to provide a secondary arc extinguisher for a power system that can extinguish secondary arcs within a short time even if an error is included in the calculation of a reference line constant.

[Brief explanation of drawings]

Figure 1 is a system configuration diagram to explain the state in which secondary arcs occur, and Figures 2 and 3 are diagrams showing the system configuration when a fixed reactor with zero-phase compensation is installed on a single-circuit transmission line and a double-circuit transmission line. System configuration diagram, 4th
The figure is a system diagram showing an example of the basic configuration of the present invention.
FIG. 5 is a block diagram showing the internal structure of the firing angle phase comparison controller in the same embodiment, and FIG. 6 is a flowchart showing the operation of the same embodiment. L ₁ to _{L 6} ...Reactor, L _g ... Neutral point reactor, THY ... Thyristor, CT ₂ ... Current transformer,
PD ₂ ... Potential transformer, PRO ... Protection relay,
CONT... Firing angle control device, PHC... Firing phase comparison controller, PC... Phase control circuit, PG... Pulse oscillator.

Claims (1)

[Claims] 1. Each phase reactor star-connected to each phase line of a two-line power transmission line via a thyristor in series, and a neutral point connected between the neutral point of each phase reactor and the ground. a protection relay that receives detection signals of the current flowing through the power transmission line and the power station bus voltage, and outputs a trip signal to protect the power transmission line when a power transmission line fault is detected;
an arc voltage detector that detects the arc voltage of the power transmission line; a neutral point current detector that detects the neutral point current flowing through the neutral point reactor; and a neutral point current detector that starts when receiving the operating output of the protective relay. and a firing angle control device that controls the firing angle of the thyristor, and when the firing angle control device is started by the operation of the protection relay, the firing angle control device calculates the optimum reactance value determined for each fault phase stored in advance in the storage means. a first gate that gate-controls the thyristor of each phase so that the reactance value of each phase reactor becomes its optimum reactance value by taking in a reactance value corresponding to the faulty phase detected by the protection relay from among the reactance values; When the thyristors of each phase are gate-controlled by the ignition control means and the first gate ignition control means, the arc voltage and neutral point current detected by the arc voltage detector and the neutral point current detector are controlled. as a feedback element, and gate-controls the thyristors of each phase while changing the optimum reactance value according to the magnitude of the arc voltage and neutral point current until the arc voltage reaches zero or a minimum value. A secondary arc extinguishing device for an electric power system, characterized in that it is comprised of a gate ignition control means.