JPS6013435A - Control system of resistor for attenuating harmonic 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 [Technical Field of the Invention] The present invention relates to a harmonic current attenuation resistor (hereinafter referred to as a power This invention relates to a control method when a resistor (referred to as a resistor) is added to the system.

[Technical background of the invention and its problems] In recent years, with the expansion and development of power systems, there has been a tendency for power systems to become more flexible due to the introduction of ultra-high voltage cable systems and the increase in phase adjustment capacitors. . In the near future,
Cable system for ultra-high voltage system (500kV system) and U
The introduction of HV systems is expected, and power systems will become more and more inclusive. In this way, as it is well known that there is a large amount of phase advance capacitance in a power system, when a power system fails, harmonic 'a lightning current is Occurrence and protection of the system I!
It may have a negative effect on the electric field. In particular, assuming a cable system with a phase advance capacity of 500 kV, the order of harmonics generated by a system failure at this time is 1 of the fundamental wave.
．． In some cases, the order is extremely low, about 5 to 2 times. These low-order harmonic currents have large current values, and the proportion (content) of the harmonic currents in the fault current can reach several hundred percent.

Furthermore, since these low-order harmonics are poorly attenuated, in the event of a system failure in such a system, low-order and large harmonic currents will remain in the system for a long time, resulting in malfunction or failure of the protective relay device. The negative impact on the power system, such as overloading of system equipment and operation, is immeasurable.

Therefore, in order to quickly eliminate such harmonic currents, it has recently been considered to add a power resistor to the power system. FIG. 1 is a single line diagram showing an example of the case where this power resistor is included. In the figure, 1
is a harmonic generation source having a phase advance capacity such as a cable system, 2 is a ground capacitance which is its phase advance capacity H, and 3 is a harmonic generation source 1
3' is a power transmission line, 4 is a switch, 5 is a power resistor, and 6 is a control device for controlling the switch 4 such as a circuit breaker.

In this configuration, the switch 4 is normally open, and the power resistor 5 is not connected to the power system.

On the other hand, when a system failure such as a three-wire short circuit occurs in the power transmission line 3 and harmonic current is generated from the harmonic generation source 1, the control device 6 closes the switch 4 and the power resistor 5 joins the power system. be done. This allows the harmonic current to be rapidly attenuated.

By the way, in this case, it is necessary to turn on the power resistor 5 reliably when harmonic current is generated due to a system failure, and in order to increase its effectiveness, it must be turned on quickly after the failure occurs. There is a need to do. On the other hand, if the current resistor 5 is turned on even when no harmonic current is being generated, the load will temporarily increase, causing the power system demand to become unbalanced and causing an overload state in the power system. Not only that, but in some cases, it may also have a negative impact on the stability of the system.

[Object of the invention] The present invention was made in consideration of the above circumstances, and
The purpose is to provide a control method for power resistors that allows power resistors to be turned on only when necessary, and to quickly attenuate harmonic currents without adversely affecting the power system. .

[Summary of the Invention] In order to achieve the above object, in the present invention, when a power resistor is added to the grid, when it is not necessary to add the power resistor to the grid, it is not added, and harmonics are The system is characterized in that the power resistor is quickly connected only when it is necessary to immediately connect the power resistor to the grid, such as when a current is generated.

[Embodiments of the Invention] A first embodiment of the present invention will be described below with reference to FIG. FIG. 2 shows a configuration example of a control system for a power resistor according to the present invention, and the same parts as those in FIG. In Fig. 2, 7 is a potential transformer (PD or P
T), 6 is an undervoltage relay (hereinafter referred to as UV) 61
A control device comprising a fundamental wave filter 62 for converting this UV 61 into a fundamental wave response wave outputs a command 8 to close the switch 4 on the condition that this tJV 61 is activated.

Next, the operation of this embodiment will be explained using FIG. 2. First, the switch 4 is normally open and the power resistor 5 is not connected to the power system.

On the other hand, when a system failure such as a ground fault or short circuit occurs in the power transmission line 3', a harmonic current is generated from the harmonic generation source 1, and at the same time, the occurrence of a system failure is detected by the operation of UV 61 in the control device 6. Then, a closing command 8 is given to the switch 4. This allows the power resistor 5 to be added to the system to quickly eliminate harmonic currents. Here, the UV6'l in the control device H6 is of the fundamental wave response type and the fundamental wave filter 62 is provided because if there is a failure in the system, the voltage of the fundamental voltage will drop, but due to the generation of harmonics, the harmonic This is because there is a voltage corresponding to the amount of voltage, so there is a possibility that it will not operate unless it is of the fundamental wave response type U■. Therefore, the fundamental wave responsive type UV
By setting 61 as the closing condition for the switch 4, a system failure can be detected reliably and quickly, and the power resistor 5 can be added to the system when necessary.

In the description of this embodiment, the closing condition for the switch 4 is the operation of the fundamental wave response type UV61, but this can also be set as a condition for the operation of the fundamental wave response type change range UV relay that detects changes in voltage. Exactly the same effect can be obtained.

FIG. 3 shows a second embodiment of the present invention, and the same parts as those in FIG. 1 are given the same reference numerals and their explanation will be omitted.

In other words, in this embodiment, the harmonic-responsive overcurrent Il! is used as the closing condition for the switch 4! It uses the operating conditions of electrical appliances.

In the figure, 7' is an instrument current transformer (CT) installed at the outlet of harmonic generation order 1, 6 is an overcurrent relay 63, and this overcurrent relay (QC) 63 is of a harmonic responsive type. This is a control device consisting of a harmonic filter 64 of 0.
A command 8 for closing the switch 4 is output on condition that C63 is activated.

FIG. 4 shows a third embodiment of the present invention, and the same parts as those in FIG. 1 are given the same reference numerals and their explanation will be omitted.

In other words, this embodiment detects the harmonic current and the fundamental wave current at the outlet of the harmonic generation source 1 as a closing condition for the switch 4, and detects that the ratio of the harmonic current to the fundamental wave current has exceeded a certain value. This was used as a condition. In the figure, 6 indicates a fundamental wave current detection element (denoted as fQ) 61, a harmonic current detection element (denoted as fn) 64, and a state in which the ratio of the harmonic current fn to the fundamental energized ifo exceeds a certain value; In other words, it is a control device consisting of an element 65 that detects fn/fo≧K (K: constant), and when a harmonic current is generated from the harmonic generation source 1 due to a system failure and the above equation is established, the harmonic A command 8 for closing the switch 4 is output by detecting the generation of current.

Note that in the methods according to the second and third embodiments, the switch 9-4 is closed in the case of a system failure that does not involve the generation of harmonic current, compared to the method using Uv in the first embodiment. First, there is an advantage that the switch 4 can be closed only when a harmonic current is generated and needs to be attenuated.

FIG. 5 shows a fourth embodiment of the present invention, and the same parts as those in FIG. 1 are given the same reference numerals and their explanation will be omitted.

That is, in this embodiment, the conditions under which a system failure has been detected are transferred to the Sendenki Station, and the switch 4 is turned on based on the received conditions. In the figure, 9 is a bus bar, 10 is a power transmission line, and 11 is a power line.
is a failure detection device, and 12 is a transfer signal. When a failure occurs in the power transmission line 10, the failure detection device @11 detects it, and the transfer signal 12 is sent to the control device 6, which receives it. A closing command 8 is given to the switch 4.

Moreover, FIG. 6 shows the case where the power resistor 5 is connected in series with the system at the outlet of the harmonic generation source 1, and the switch 4 is connected in parallel with the power resistor 5. In this case,
The switch 4 is normally closed, and the system is the same as if the power resistor 5 were not connected. On the other hand, when a harmonic current is generated from the harmonic generation m110-, the switch 4 is opened, so that the power resistor 5 is connected in series to the grid. The effect that the addition of the power resistor 5 at this time contributes to the rapid disappearance of harmonic current is exactly the same as when the power resistor 5 is connected in parallel to the grid. therefore,
The conditions for connecting the power resistor 5 to the grid are also exactly the same as the conditions for connecting the power resistor 5 in parallel to the grid.

However, in this case, the switch 4 will be opened depending on the detection condition of a system failure or harmonic generation.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may include a method using the above-mentioned UV1 change width UV, harmonic responsive type OC, etc., a method using the ratio of harmonic current to fundamental wave current as a condition, and others. A combination of two or more methods, such as the method of transferring data from an electric station, can also be implemented in the same way.

FIG. 7 shows a combination of the fundamental wave response type UV66 and the harmonic response type 0C67, and an AND condition of the two conditions (output is output when both LIV and OC operate) using an AND circuit 68. This shows what is used. Of course, conditions other than UV and OC may be used, or three or more conditions may be used. In this way, by combining multiple conditions, the possibility of erroneously closing the switch 4 is reduced, and the power resistor 5 is connected only when necessary.
can be added to the system.

Further, in each of the embodiments described above, the switch 4 is not limited to a breaker, and a cyrisk switch may also be used. In the case of this thyrisk switch, instead of giving a closing command to the switch, an ON signal is given to the gate circuit, and instead of giving an opening command to the switch, an ON signal is given to the gate circuit.
All that is required is to give the F signal.

[Effects of the Invention] As explained above, according to the present invention, when a power resistor is added to the grid, it is not added when there is no need to add the power resistor to the grid, and harmonics are Only when it is necessary to immediately add a power resistor to the power grid, such as when a current is generated, do you quickly add a power resistor to quickly remove harmonic current without adversely affecting the power grid. A highly reliable control method for a power resistor that can attenuate the power resistor can be provided.

[Brief explanation of the drawing]

Fig. 1 is a single line diagram for explaining the insertion of a power resistor, Fig. 2 is a configuration diagram showing the first embodiment of the present invention, and Fig. 3 is a configuration diagram showing the first embodiment of the present invention.
5 to 5 are block diagrams showing second to fourth embodiments of the present invention, and FIGS. 6 and 7 are block diagrams showing other embodiments of the present invention. 1...Harmonic generation source, 2...Ground capacitance, 3,9
...Bus bar, 3', 10...Power transmission line, 4...Switch, 5...Power resistor, 6...Control device, 7...
Instrument transformer (PD or PT), 7=... Instrument current transformer (CT), 8... Switch closing command, 11... Failure detection device, 12... Transfer signal, 13. ...Switch open command, 61...UV162...Fundamental wave filter, 63...QC, 64...Harmonic filter, 65
...Level detection element, 66...Fundamental wave response type UV,
67...Harmonic response type 0C168...AND circuit. =13- JP-A-Sho GO-13435 (5)

Claims (5)

[Claims] (1) For harmonic current attenuation, a power resistor for harmonic attenuation is added to the power system by controlling a switch for the ground capacitance that exists between the power system and the ground. In the resistor control method, the power resistor is connected to the power system on the condition that a fundamental wave responsive undervoltage relay connected to the secondary side of the potential transformer installed in the power system is activated. A control method for a resistor for harmonic current attenuation, which is characterized by the following: (2) A control system for a harmonic current attenuation resistor according to claim (1), wherein the fundamental wave responsive undervoltage relay is a fundamental wave responsive undervoltage relay. (3) For harmonic current attenuation, a power resistor for harmonic attenuation is added to the power system by controlling a switch for the ground capacitance that exists between the power system and the ground. In the resistor control method, the power supply is controlled on the condition that a harmonic-responsive overcurrent relay connected to the secondary side of an instrument current transformer installed at the outlet of a harmonic generation source of the power system operates. A control method for a harmonic current attenuation resistor, which is characterized by incorporating the resistor into the power system. (4) For harmonic current attenuation, a power resistor for harmonic attenuation is added to the power system by controlling a switch for the ground capacitance that exists between the power system and the ground. In the resistor control method, the ratio of the harmonic current to the fundamental current detected at the instrument current transformer installed at the outlet of the harmonic generation source of the power system exceeds a certain value. 1. A control method for a harmonic current attenuating resistor, characterized in that the power resistor is connected to a power system on the condition that this is detected. (5) - Harmonic current attenuation by adding a power resistor for harmonic attenuation to the power system by controlling a switch for the ground capacitance that exists between the power system and the ground. In the control method for the power resistor, the power resistor is connected to the power system on the condition that a failure detection device transfers and receives a signal indicating that a failure in the power system has been detected at another electric station. A control method for harmonic current attenuation resistors.