JPH0819168A - Method and apparatus for protective relaying of dc transmission line - Google Patents

Abstract

PURPOSE:To effectively protect a DC transmission system by a method wherein, after a current at the end of a rectifier has been increased at a change rate of a definite magnitude or higher, it is decreased at a definite magnitude or higher within a prescribed time and the fault of a DC transmission line is judged when a current change rate at the end of an inverter displays a transition which is opposite to that at the end of the rectifier. CONSTITUTION:A first signal which is output from a rectifier-side-current- change-rate detection device 22 and a second signal which holds the first signal in a hold device 24 for a definite period so as to be output are sent to a current- change-pattern discrimination device 26. On the other hand, on the side of an inverter, a second signal from a change-rate detection device 23 and a first signal which holds the second signal in a hold device 25 so as to be output are sent to a pattern discrimination device 27. Signals from the two discrimination devices 26, 27 are input to an accident discrimination device 29, and it is judged whether peak patterns of both are an isophase or an antiphase. Thereby, the commutation failure of an inverter 2 and the failure of DC transmission lines 9, 10 can be discriminated without any error.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective relay method for a direct current transmission line and a protective relay device for a direct current transmission line, which effectively protects the direct current transmission system against a failure of the direct current transmission line. is there.

[0002]

2. Description of the Related Art When a fault such as a short circuit or a ground fault occurs in the line of a DC power transmission system as is conventionally done in an AC power transmission system, those faults are promptly detected and the fault section is determined. It must be removed to protect the DC transmission system. A current change amount direction comparison method is used for a conventional DC power transmission line protection relay method or DC power transmission line protection relay device for protecting such a DC power transmission system. FIG. 9 is a system diagram showing a configuration of a DC power transmission line protection relay method or a DC power transmission line protection relay device using such a current variation direction comparison method. In the figure, 1 is a forward converter for converting AC power into DC power,
Reference numeral 2 is an inverse converter for converting DC power into AC power, and 3 and 4 are AC power supplies. Reference numerals 5 and 6 are DC reactors, 7 and 8 are DC current detectors, and 9 and 10 are DC transmission lines. Reference numeral 11 is a protective relay device that protects the DC transmission lines 9 and 10 by detecting failures when a failure such as a short circuit or a ground fault occurs and removing the failure section. Reference numerals 12 and 13 denote current change direction detection devices, which detect an increase / decrease in direct current. Reference numeral 14 is an accident discriminating device for discriminating a DC line fault when an increase in direct current on the forward converter 1 side and a decrease on direct current on the reverse converter 2 side are simultaneously detected, and 15 is detected by the current change direction detecting device 13. This is a transmission device that sends increase / decrease data of DC current to the accident determination device 14.

Next, the operation will be described. In such a DC power transmission system, the currents flowing through the DC current detectors 7 and 8 are equal in a steady state, but as shown in FIG. 7, when a DC line fault occurs, the DC current on the side of the forward converter 1 increases and the reverse converter 1 increases. The DC current on the second side decreases. The protective relay device 11 is
When an increase in the DC current on the forward converter 1 side and a decrease in the DC current on the inverse converter 2 side occur at the same time, it is determined that an accident has occurred in the DC lines 9 and 10, and the DC transmission system protection operation is performed.

[0004]

Since the conventional protective relay method for a DC transmission line or the conventional protective relay device for a DC transmission line is constructed as described above, when the commutation of the reverse converter 2 fails, as shown in FIG. Since a DC current as shown in Fig. 4 flows, the increase in the DC current on the forward converter 1 side and the DC current on the inverse converter 2 side due to the influence of the transmission delay time of information about the increase or decrease of the DC current and the inductance component of the line. However, there is a problem in that it may be erroneously determined that a DC line accident has occurred.

The inventions of claims 1 to 4 were made in order to solve the above-mentioned problems, and a DC power transmission system can be provided without misjudging a commutation failure of an inverse converter as a DC line fault. The purpose is to obtain a protection relay method for a DC transmission line that is effectively protected.

The inventions of claims 5 to 8 provide a protective relay device for a DC transmission line which effectively protects a DC transmission system without misjudging a commutation failure of an inverse converter as a DC line fault. With the goal.

[0007]

According to a first aspect of the present invention, there is provided a protective relay method for a DC power transmission line, wherein the current of the DC power transmission line at a forward converter end is increased at a current change rate of a certain magnitude or more. After the current change rate decreases by a certain magnitude or more within a later predetermined time and the current of the DC transmission line decreases by a current change rate of a certain magnitude or more at the inverse converter end, It is determined that the DC transmission line is faulty when the current change rate increases by a certain magnitude or more within the time of,
It is provided with a configuration for shifting to the protection operation of the DC power transmission system.

According to another aspect of the present invention, there is provided a protective relay method for a DC power transmission line, wherein the current of the DC power transmission line is increased within a predetermined time after the current of the DC power transmission line is increased by a change amount of a certain magnitude or more at a forward converter end. While the amount of change in the current decreases by a certain amount or more, the current of the DC transmission line at the inverse converter end decreases by a certain amount of change in the certain amount or more. A configuration is provided in which when the amount of change increases by a certain amount or more, it is determined that the DC transmission line has failed, and the operation shifts to the protection operation of the DC transmission system.

According to a third aspect of the present invention, there is provided a protective relay method for a DC power transmission line, wherein the current of the DC power transmission line at the forward converter end increases at a rate of change above a certain magnitude and at the reverse converter end. When the current of the DC transmission line decreases at a certain rate of change or more, and when the DC voltage of the DC transmission line changes at a certain voltage change rate or more, it is determined that the DC transmission line has a failure. However, it is provided with a configuration for shifting to the protection operation of the DC power transmission system.

According to a fourth aspect of the present invention, there is provided a protective relay method for a DC power transmission line, wherein the current of the DC power transmission line at the forward converter end is increased by a change amount of a certain magnitude or more and at the reverse converter end. When the current of the DC transmission line decreases by a certain amount of change or more, and when the DC voltage of the DC transmission line changes at a certain voltage change rate of more than a certain amount, it is determined that the DC transmission line has failed. However, it is provided with a configuration for shifting to the protection operation of the DC power transmission system.

According to a fifth aspect of the present invention, there is provided a protective relay device for a DC power transmission line, wherein the current change rate detecting device detects that the current of the DC power transmission line has increased at a rate of change equal to or more than a certain magnitude at the forward converter end. It is shown that, after the first signal shown is output, the current of the DC transmission line decreases at a change rate of a certain magnitude or more within a predetermined time during which the hold device holds the first signal. The second signal is output, and the first signal is output within a predetermined time when the hold device holds the second signal output from the current change rate detection device at the inverse converter end. It is configured to include a determination unit that determines the above and outputs a protection operation signal.

According to a sixth aspect of the present invention, there is provided a protective relay device for a direct current power transmission line, wherein a current change amount detection device at a forward converter end detects that the current of the direct current power transmission line has increased by a predetermined change amount or more. Indicates that the current of the DC transmission line has decreased by a change amount of a certain magnitude or more within a predetermined time during which the hold device holds the first signal after the first signal is output. The second signal is output, and at the same time, the second output signal is output from the current change amount detection device at the inverse converter end.
It is configured to include a determination unit that determines that the first signal has been output within a predetermined time period in which the hold device holds the signal of 1) and outputs the protection operation signal.

According to a seventh aspect of the present invention, there is provided a protective relay device for a DC power transmission line, wherein a current change rate detecting device detects that the current of the DC power transmission line has increased at a rate of change equal to or more than a certain magnitude at a forward converter end. And a second signal indicating that the current change rate detecting device has decreased the current of the DC transmission line at a change rate of a certain magnitude or more at the inverse converter end. Determination means for outputting a protection operation signal based on the fact that the voltage change rate detection device has detected a voltage change rate of a certain level or more of the DC voltage of the DC transmission line, and the above conditions are both satisfied. It is configured to include.

According to another aspect of the present invention, there is provided a protective relay device for a DC power transmission line, wherein the current change amount detecting device at the forward converter end detects that the current of the DC power transmission line has increased by a certain amount or more. And a second signal indicating that the current of the DC power transmission line has decreased at the end of the inverse converter from the current change amount detection device with a change amount of a certain magnitude or more. Determination means for outputting a protection operation signal based on the fact that the voltage change rate detection device has detected a voltage change rate of a certain level or more of the DC voltage of the DC transmission line, and the above conditions are both satisfied. It is configured to include.

[0015]

According to the first aspect of the present invention, there is provided a protective relay method for a DC power transmission line, wherein the current of the DC power transmission line at the end of the forward converter is increased at a current change rate of a certain magnitude or more and then within a predetermined time. When the current change rate of the current of the DC transmission line at the inverse converter end shows a transition opposite to that at the forward converter end, it is determined that the DC transmission line has failed. , The operation of protection of the DC power transmission system is transitioned, it is determined that it is different from the commutation failure of the inverse converter, and the protection of the DC transmission system is enabled without misidentifying the failure of the commutation of the inverse converter as a DC line fault. Act to do.

According to a second aspect of the present invention, there is provided a protective relay method for a DC power transmission line, wherein the current of the DC power transmission line at the end of the forward converter is increased by a current change amount of a certain magnitude or more and then within a predetermined time. When the current change amount of the current of the DC transmission line at the inverse converter end shows a transition opposite to that of the forward converter end, it is determined that the DC transmission line has failed. , The operation of protection of the DC power transmission system is transitioned, it is determined that it is different from the commutation failure of the inverse converter, and the protection of the DC transmission system is enabled without misidentifying the failure of the commutation of the inverse converter as a DC line fault. Act to do.

According to a third aspect of the present invention, there is provided a protective relay method for a DC power transmission line, wherein the voltage change rate of the DC voltage of the DC power transmission line in the case of a DC line fault is more than the voltage change rate when the commutation of the reverse converter fails. Paying attention to the fact that it is large, the current of the DC transmission line at the end of the forward converter increases at a rate of change above a certain level,
Furthermore, when the current of the DC transmission line at the end of the inverse converter decreases at a rate of change equal to or higher than a certain magnitude, and when the DC voltage of the DC transmission line changes at a rate of voltage change equal to or higher than a certain level, It is determined that the failure of the DC converter is not the commutation failure of the inverse converter, and the operation shifts to the protection operation of the DC transmission system, and the failure of the commutation of the inverse converter is protected without mistakenly determining it as a DC line accident. To act effectively.

According to a fourth aspect of the present invention, there is provided a protective relay method for a DC transmission line, wherein the rate of change in the DC voltage of the DC transmission line in the event of a DC line fault is the voltage of the DC voltage when the commutation of the inverse converter fails. Paying attention to the fact that it is larger than the rate of change, the current of the DC power transmission line at the forward converter end increases with a certain amount of change or more, and the current of the DC power transmission line at the inverse converter end has a certain magnitude. When the DC voltage of the DC transmission line changes at a certain voltage change rate or more, it is determined that the DC transmission line has a failure different from the commutation failure of the inverse converter, and the DC It shifts to the protection operation of the power transmission system, and acts to effectively protect the DC power transmission system without erroneously determining the commutation failure of the inverse converter as a DC line fault.

According to a fifth aspect of the present invention, there is provided a protective relay device for a direct current power transmission line, which shows that an increase in current in the direct current power transmission line is detected at a rate of change of a certain magnitude or more at a forward converter end. After the signal is output, a second signal indicating that the current of the DC transmission line has decreased at a rate of change equal to or higher than a certain magnitude is output within a predetermined time, and at the same time, at a constant rate at the inverse converter end. After the second signal indicating that the decrease in the current of the DC transmission line is detected at a rate of change equal to or larger than the magnitude is output, the current of the DC transmission line increases at a rate of change equal to or greater than a certain magnitude. Is output within a predetermined time, it is determined that the DC transmission line has a fault different from the commutation failure of the inverse converter, and the commutation failure of the inverse converter is mistaken as a DC line fault. Acts to effectively protect the DC transmission system without judgment

According to a sixth aspect of the present invention, there is provided a protective relay device for a direct current power transmission line, which is directed to the first embodiment, which indicates that an increase in the current of the direct current power transmission line is detected at a forward converter end by a change amount equal to or larger than a predetermined magnitude. After the signal is output, a second signal indicating that the current of the DC transmission line has decreased by a change amount equal to or larger than a certain fixed amount is output within a predetermined time, and at the same time, the second signal is fixed at the inverse converter end. After the output of the second signal indicating that the decrease in the current of the DC transmission line with the change amount of the magnitude or more is detected, the current of the DC transmission line increases with the change amount of the certain amount or more. Is output within a predetermined time, it is determined that the DC transmission line has an accident different from the commutation failure of the inverse converter, and the commutation failure of the inverse converter is mistaken as a DC line accident. Acts to effectively protect the DC transmission system without judgment

According to a seventh aspect of the present invention, there is provided a protective relay device for a direct current power transmission line, which shows that an increase in the current of the direct current power transmission line with a rate of change of a certain magnitude or more is detected at a forward converter end. As the signal is output, the transition of the rate of change of the current of the DC transmission line at the inverse converter end is opposite to the transition of the rate of change of the current at the forward converter end, and there is a DC voltage of the DC transmission line. When the voltage change rate exceeds a certain level, it is determined that the DC transmission line has a failure different from the commutation failure of the inverse converter, the DC transmission line system protection operation starts, and the commutation failure of the inverse converter occurs. Acts so as to effectively protect the DC transmission system without erroneously determining the DC line fault.

According to a eighth aspect of the present invention, there is provided a protective relay device for a direct current power transmission line, which shows that an increase in the current of the direct current power transmission line is detected at a forward converter end by a change amount of a certain magnitude or more. As the signal is output, the transition of the amount of change in the current of the DC transmission line at the inverse converter end is opposite to the transition of the amount of change in the current at the forward converter end, and the DC voltage of the DC transmission line is constant. When the voltage changes at the above rate of change, it is determined that the DC transmission line has a failure different from the commutation failure of the inverse converter, and the DC transmission system protection operation is performed. It works to protect the DC transmission system effectively without misjudging a line accident.

[0023]

【Example】

Example 1. An embodiment of the inventions of claims 1 and 5 will be described below with reference to the drawings. FIG. 1 is a system diagram showing a configuration of a protection relay device for a DC transmission line in which a method for protecting a DC transmission line according to an embodiment of the present invention is used. In FIG. 1, parts that are the same as or correspond to those in FIG. 9 are given the same reference numerals and description thereof is omitted. In the figure, 21 is a DC transmission line 9,
When a fault such as a short-circuit or a ground fault occurs in 10, the fault is detected, the fault section is removed, and the DC power transmission line protective relay device protects the DC power transmission lines 9 and 10.
22 detects the rate of change of the direct current at the end of the forward converter 1 from the magnitude of the change of the current and the time required for the change, and when the direct current increases at a rate of change above a certain level, A current change rate detecting device that outputs a signal of No. 1 and outputs a second signal when the DC current decreases at a change rate of a certain magnitude or more. Rate detectors are used. 23 is the inverse converter 2
The rate of change in the DC current at the edge is detected from the magnitude of the change in the current and the time required for that change, and the first signal is output when the DC current increases at a rate of change above a certain level. A current change rate detecting device which outputs a second signal when the direct current decreases at a change rate of a certain magnitude or more. In this embodiment, the reverse converter side current change rate detecting device is used. ing. Reference numeral 24 denotes a holding device for holding a signal relating to the current change rate output from the forward converter side current change rate detecting device 22 for a certain period of time. In this embodiment, the forward converter side hold device is used. Reference numeral 25 denotes a hold device for holding a signal related to the current change rate output from the inverse converter side current change rate detection device 23 for a certain period of time. In this embodiment, the inverse converter side hold device is used.

Reference numeral 26 is a forward converter side current change rate detection device 22.
The increase / decrease of the current is shown based on the first signal output from the second converter and the second signal output while the forward converter-side hold device 24 holds the first signal for a certain period of time. This is a determination means for determining the peak pattern, and in this embodiment, a forward converter side current change pattern determination device is used. 27 is a second signal output from the inverse converter side current change rate detection device 23, and an inverse converter side hold device 25.
In the present embodiment, the determination means determines a peak pattern indicating an increase / decrease in current based on the first signal output while holding the second signal for a certain period of time. A converter side current change pattern discriminating device is used. 29 is the inverse converter 2 sent from the inverse converter side current change pattern discrimination device 27 via the transmission device 28.
With the peak pattern determination result showing the increase or decrease of the DC current at the end,
From the peak pattern determination result output from the forward converter-side current change pattern determination device 26, which indicates the increase / decrease in the direct current at the end of the forward converter 1, it is determined whether the peak pattern determination results of both are in phase or opposite phase. By doing so, it is a determination means for determining the commutation failure of the inverse converter 2 and the failure of the DC power transmission lines 9 and 10, and outputting a protection operation signal when the DC power transmission line has a failure. An accident determination device is used.

Next, the operation will be described. As shown in FIG. 7, in the case of a DC line fault, the DC current on the forward converter 1 side increases within a fixed time and then decreases, but the DC current on the inverse converter 2 side decreases and then increases. On the other hand, when the commutation of the reverse converter 2 fails, as shown in FIG. 8, both the direct current on the forward converter 1 side and the direct current on the reverse converter 2 side increase within a certain fixed time and then decrease. That is, the peak pattern determination result indicating the increase / decrease in the DC current output from the forward converter-side current change pattern determination device 26 and the reverse converter-side current change pattern determination device 27 is in the reverse phase when the DC line fault occurs, and in the same phase when the commutation fails. Is.

Paying attention to the difference in the peak patterns of the DC currents on the forward converter 1 side and the inverse converter 2 side, the first signal output from the forward converter side current change rate detection device 22 is forward converted. The device-side holding device 24 is held for a certain period of time, and the second signal output during that time and the second signal output from the inverse converter-side current change rate detection device 23 are held by the inverse converter-side holding device 25. By determining whether the AND condition with the first signal output while being held for a certain period of time is satisfied, the accident determination device 29 causes the forward converter-side current change pattern determination device 26 and the inverse conversion device to perform reverse conversion. The peak pattern determination results including the directions of increase / decrease in the change of the DC current on the forward converter 1 side and the inverse converter 2 side, which are respectively output from the device-side current change pattern determination device 27, have the same phase or the opposite phase. It is judged whether it is the reverse conversion with the forward converter 1 side. When the peak pattern determination results show that both DC currents on the two sides have the same phase that increases within a certain time and then decreases, a commutation failure of the inverse converter 2 that is not a DC line fault. Then, the protection operation is locked.

Further, the increase / decrease in the direct current on the side of the forward converter 1 is
It has a peak pattern that increases within a certain time and then decreases, and a peak pattern in which the increase / decrease in the DC current on the inverse converter 2 side decreases and then increases within a certain time. When the peak pattern discrimination results of the both indicate that the patterns have opposite phases, it is determined that the DC line fault occurs, and the protection operation signal is output to perform the DC system protection operation.

In the embodiment described above, the rate of change of the DC current on the side of the forward converter 1 and the side of the inverse converter 2 is detected, and the rate of change when the rate of change of the DC current changes. ，
Based on the pattern and sequence of current changes, a series of operations for determining a DC line fault is performed by the forward converter-side current change rate detection device 22 provided on the forward converter 1 side and the inverse converter 2 side, respectively. The device-side current change rate detection device 23, the forward converter-side hold device 24, the inverse converter-side hold device 25, the forward converter-side current change pattern determination device 26, and the inverse converter-side current change pattern determination device 27. However, the forward converter side current change rate detection device 22 and the inverse converter side current change rate detection device 23 are combined into one current change rate detection device, and the forward converter side hold device 24 and The inverse converter side hold device 25 is configured as one holding device, and the forward converter side current change pattern determination device 26 and the inverse converter side current change pattern determination device 27 are configured as one current change pattern determination device. And it may be the these current change rate detector and hold device and the current change pattern determination device configuration the CPU controlled by multitasking. In this case, the detection data of the DC currents detected by the DC current detectors 7 and 8 are collected through the transmission device by the time division multiplexing method, or the DC current detectors 7 and 8 are individually installed. Is collected by the signal line that is set. Also,
An optical fiber may be used for the signal line in order to reduce the influence of noise on the signal line due to electromagnetic induction or the like.

FIG. 2 is a flowchart showing the protective relay operation of the protective relay device for the DC power transmission line described above.

As described above, according to this embodiment, the rate of change in DC current, the sequence of transitions, and the peak pattern of the forward converter 1 side and the inverse converter 2 side are detected, and the forward converter 1 side is detected. The magnitude of the rate of change of the direct current is not less than a certain magnitude, and further, it has a peak pattern in which the polarity changes from positive to negative, and the magnitude of the rate of change of the direct current on the inverse converter 2 side is large. If a certain magnitude is greater than a certain magnitude and the polarity has a peak pattern that changes from negative to positive, a DC line fault is determined and a protection operation signal is output. It is possible to reliably discriminate between commutation failure and DC line fault, and it is possible to effectively protect the DC transmission system.

Embodiment 2 FIG. Next, claim 2 and claim 6
An embodiment of the invention will be described with reference to the drawings. FIG. 3 is a system diagram showing a configuration of a DC power transmission line protective relay device in which a DC power transmission line protection relay method according to an embodiment of the present invention is used. 3, parts that are the same as or correspond to those in FIG. 1 are assigned the same reference numerals and explanations thereof are omitted. In the figure, reference numeral 31 indicates a DC power transmission line protection protection that protects the DC power transmission lines 9 and 10 when the DC power transmission lines 9 and 10 have failures such as a short circuit or a ground fault. It is an electric device. Reference numeral 32 detects the amount of change in the direct current at the end of the forward converter 1 above a certain level, outputs a first signal when the amount of change increases above a certain level, and decreases when the amount of change exceeds a certain level. A current change amount detection device for outputting a second signal, and in this embodiment, a forward converter side current change amount detection device is used. Reference numeral 33 detects the amount of change in the DC current at the end of the inverse converter 2 above a certain level, outputs a first signal when the amount of change increases above a certain level, and decreases when the amount of change exceeds a certain level. This is a current change amount detection device that outputs a second signal, and in this embodiment, an inverse converter side current change amount detection device is used.

Reference numeral 34 is a forward converter side current change amount detection device 32.
From the first signal relating to the amount of change in the direct current at the end of the forward converter 1 and the first converter holding device (hold device) 35 while holding the first signal for a certain period of time. This is a determination means for determining a peak pattern indicating an increase / decrease in current based on the obtained second signal. In this embodiment, a forward converter side current change pattern determination device is used. Reference numeral 36 denotes the second signal relating to the change amount of the direct current at the end of the inverse converter 2 output from the inverse converter side current change amount detection device 33, and the second signal in the inverse converter side hold device (hold device) 37. Is a determination means for determining a peak pattern showing an increase / decrease in the current based on the obtained first signal while holding the signal for a certain period of time. A pattern discriminator is used. Reference numeral 38 denotes a peak pattern determination result indicating an increase / decrease in the DC current at the end of the inverse converter 2 sent from the inverse converter side current change pattern determination device 36 via the transmission device 28, and a forward converter side current change pattern determination. From the peak pattern determination result indicating the increase / decrease in the direct current at the end of the forward converter 1 output from the device 34, it is determined whether the peak pattern determination results of both of them, which are sent at the same time, have the same phase or opposite phase. Is a determination means that determines a commutation failure of the inverse converter 2 and a failure of the DC power transmission lines 9 and 10 and outputs a protection operation signal when the DC power transmission line has a failure. In this embodiment, an accident determination device. Is used.

In the first embodiment, in order to obtain the rate of change of the current, information on the magnitude of the change in the current and the time required for the change is required, but in the present embodiment, the current is determined only by the magnitude of the change in the current. Since it is possible to know the direction of change of the current change rate detection device, the forward converter side current change amount detection device 32 and the reverse converter side current change amount detection device 33 having a simpler configuration than the current change rate detection device
Thus, it is possible to obtain the amount of change in the direct current and obtain information regarding the direction of change in the current.

In the operation of this embodiment, the first signal output from the forward converter side current change amount detection device 32 is sent to the forward converter side hold device 35 and the inverse converter side current change amount detection device 33. Whether or not the AND condition of the second signal and the first signal output during that time is held in the inverse converter side holding device 37 for a fixed time respectively. Therefore, the accident discriminating device 38 determines whether the forward converter 1 side and the inverse converter 2 side output from the forward converter side current change pattern discriminating device 34 and the inverse converter side current change pattern discriminating device 36 respectively. It is determined whether the peak pattern determination result indicating the direction of increase or decrease in the amount of change in DC current is in phase or in antiphase, and if it is in phase, it is not a DC line fault and the inverter 2 It is judged that it is a flow failure,
Lock protection action.

When the peak pattern determination result is in the opposite phase, it is determined that the DC line fault occurs and the protection operation signal is output to perform the protection operation of the DC transmission system.

As described above, according to the present embodiment, the forward converter 1 has the peak pattern in which the amount of change in the direct current changes from the increasing direction to the decreasing direction, and the inverse converter 2 When there is a peak pattern in which the amount of change in the direct current on the side changes from a decreasing direction to an increasing direction, it is determined that there is a DC line fault and a protection operation signal is output. The failure and the DC line accident can be reliably discriminated, and the DC transmission system can be effectively protected.

Example 3. Next, claim 3 and claim 7
An embodiment of the invention will be described with reference to the drawings. FIG. 4 is a system diagram showing a configuration of a DC power transmission line protective relay device using a DC power transmission line protective relay method according to an embodiment of the present invention. 4, parts that are the same as or equivalent to those in FIG. 1 are given the same reference numerals and explanations thereof are omitted. In the figure, 40 is a DC voltage detector that detects the DC voltage of the DC transmission lines 9 and 10, and 41 is a voltage change when the DC voltage detected by the DC voltage detector 40 is a change rate of a certain magnitude or more. A voltage change rate detection device that outputs a detection signal, 42 is a first signal detected by the forward converter side current change rate detection device 22, a voltage change detection signal detected by the voltage change rate detection device 42, and a reverse signal. An accident determination device (determination means) that determines a failure of the DC transmission line and outputs a protection operation signal of the DC transmission line based on the second signal detected by the converter-side current change rate detection device 23.

Reference numeral 43 is a forward converter side current change rate detection device 2.
2 and a reverse converter side current change rate detection device 23, a voltage change rate detection device 41, an accident determination device 42, and the like, and the current of the DC transmission line at the end of the forward converter 1 has a change rate of a certain magnitude or more. When the current of the DC transmission line at the end of the inverse converter 2 decreases with a change rate of a certain magnitude or more as it increases, and when the DC voltage of the DC transmission line changes with a certain rate of voltage change or more, It is a protective relay device for a DC power transmission line, which determines that the DC power transmission line is out of order and outputs a protection operation signal for the DC power transmission line.

Next, the operation of this embodiment will be described.
When a DC line fault occurs, the DC current on the forward converter 1 side increases,
The DC current on the side of the inverse converter 2 decreases, and the DC voltage sharply decreases with a large rate of change. On the other hand, when the reverse converter 2 fails in commutation, the DC voltage of the DC transmission line changes at a relatively small rate of change. Therefore, in this embodiment, the DC current on the forward converter 1 side increases and the DC voltage on the inverse converter 2 side increases. The current change is detected at a change rate of a certain magnitude or more, and the voltage change rate detecting device 4
When it is detected that the DC voltage has decreased at a rate of change equal to or greater than a certain magnitude, it is determined to be a DC line fault and the DC transmission line protection operation is performed.

FIG. 5 is a flow chart showing an accident detection protection operation of the protection relay device for the DC transmission line described above.

According to this embodiment, the rate of change of the direct current on the side of the forward converter 1 and the side of the inverse converter 2 are detected, and the rate of change of the direct current on the side of the forward converter 1 is above a certain level. The DC current changes in the direction of increase and the inverse converter 2
If the rate of change of the DC current on the side of the DC line changes toward a certain magnitude or more, the DC current decreases, and if it is detected that the DC voltage decreases at a rate of more than a certain magnitude, the DC line is detected. Since it is judged as an accident and the protection operation signal is output, it is possible to surely distinguish between the commutation failure of the inverse converter and the DC line accident, and it is possible to effectively protect the DC transmission system. .

Example 4. Next, claim 4 and claim 8
An embodiment of the invention will be described with reference to the drawings. FIG. 6 is a system diagram showing a configuration of a protection relay device for a DC transmission line in which a method for protecting a DC transmission line according to an embodiment of the present invention is used. 6, parts that are the same as or correspond to those in FIGS. 3 and 4 are given the same reference numerals and description thereof is omitted.

The protective relay device for the DC power transmission line of this embodiment is
The forward converter-side current change rate detecting device 22 and the inverse converter-side current change rate detecting device 23 shown in FIG. 4 are replaced with a forward converter-side current change amount detecting device 32 and an inverse converter-side current change amount detecting device 33.
The change amount of the direct current is calculated by the following. An increase in the direct current of the forward converter 1 side and a decrease in the direct current of the inverse converter 2 side are detected, and the voltage change rate detecting device detects a certain magnitude. If it is detected that the DC voltage has decreased at the above rate of change, it is determined that a DC line fault has occurred and the DC transmission system is protected.

In FIG. 6, reference numeral 52 denotes a first signal output from the forward converter side current change amount detection device 32, a voltage change detection signal output from the voltage change rate detection device 41, and an inverse converter side current change. An accident determination device (determination means) that determines a failure of the DC transmission line and outputs a protection operation signal of the DC transmission line based on the second signal output from the quantity detection device 33.

Reference numeral 53 is a forward converter side current change amount detection device 3
2 and the reverse converter side current change amount detection device 33, the voltage change rate detection device 41, the accident determination device 52, etc., and the change amount of the current of the DC transmission line at the end of the forward converter 1 is a certain magnitude or more. When the current of the DC transmission line at the end of the inverse converter 2 decreases with a change amount of a certain magnitude or more and further increases with an increase in the DC voltage of the DC transmission line with a certain voltage change rate of a certain amount or more, It is a protective relay device for a DC power transmission line, which determines that the DC power transmission line is out of order and outputs a protection operation signal for the DC power transmission line.

As described above, according to the present embodiment, the amount of change in the DC current on the forward converter 1 side and the inverse converter 2 side is detected, and the DC current on the forward converter 1 side has a certain magnitude. The amount of change in the direct current on the side of the inverse converter 2 changes in the direction of increase in the amount of change equal to or more than a certain amount, and the amount of change in the DC current of the inverse converter 2 decreases in the amount of a certain amount or more. When it detects that the DC voltage has decreased, it determines that there is a DC line fault and outputs a protection operation signal.Therefore, it is possible to reliably discriminate between commutation failure of the inverter and DC line fault. It is possible to effectively protect the DC transmission system.

[0047]

As described above, according to the first aspect of the present invention, the current of the DC transmission line at the end of the forward converter increases within a predetermined time after the current has increased at a rate of change of a certain magnitude or more. The current change rate decreases at a certain magnitude or more, and the current change rate within a predetermined time after the current of the DC transmission line at the inverse converter end decreases at a certain magnitude or more. Is determined to be a failure of the DC transmission line when it increases above a certain level, and it is configured to shift to the protection operation of the DC transmission line, so the commutation failure of the inverse converter is erroneously determined to be a DC line accident. There is an effect that a protection relay method for a DC transmission line that effectively protects the DC transmission system without being provided is obtained.

According to the second aspect of the present invention, the amount of change in the current is constant within a predetermined time after the current of the DC transmission line is increased by a certain amount of change at the end of the forward converter. If the current change amount is equal to or more than a certain magnitude within a predetermined time after the current of the DC transmission line decreases at a certain magnitude or more at the inverse converter end, When it is increased, it is determined that the DC transmission line has a failure, and since it is configured to shift to the protection operation of the DC transmission line, the DC transmission system is configured without misjudging the commutation failure of the inverse converter as the DC line fault. There is an effect that a protection relay method for a DC transmission line for effective protection can be obtained.

According to the third aspect of the present invention, the current of the DC transmission line at the forward converter end increases at a certain rate of change or more, and the current of the DC transmission line at the inverse converter end exists. Decrease at a rate of change of a certain magnitude or more, when the change in the DC voltage of the DC transmission line has changed at a rate of change of a certain amount or more, it is determined that the DC transmission line is a failure,
Since it is configured to shift to the protection operation of the DC transmission line,
There is an effect that a protection relay method for a DC transmission line can be obtained that effectively protects a DC transmission system without misjudging a commutation failure of an inverse converter as a DC line accident.

According to the fourth aspect of the present invention, the current of the DC transmission line at the forward converter end increases with a change amount larger than a certain magnitude, and the current of the DC transmission line at the inverse converter end exists. Decrease by a change amount of a certain magnitude or more, and further, when the change of the DC voltage of the DC transmission line changes at a certain rate or more of the voltage change rate, it is determined that the DC transmission line is in failure, and the DC transmission line Since it is configured to shift to the protection operation, there is an effect that a protection relay method for a DC transmission line can be obtained that effectively protects a DC transmission system without misidentifying a commutation failure of an inverse converter as a DC line fault. .

According to the fifth aspect of the present invention, the first signal output from the current change rate detecting device at the end of the forward converter and the second signal output within the predetermined time held in the hold device are combined with the second signal. , It is determined whether the second signal output from the current change rate detecting device at the end of the inverse converter is held in the hold device with the first signal output within a predetermined time, and the AND condition is established and protected. Since the protection circuit is configured to perform the protection operation of the DC transmission line by the protection operation signal output from the judgment means, the failure of commutation of the reverse converter is erroneously determined as the DC line fault. There is an effect that a protective relay device for a DC transmission line that effectively protects a DC transmission system without being provided is obtained.

According to the sixth aspect of the present invention, the first signal output from the current change amount detecting device at the end of the forward converter and the second signal output within the predetermined time held by the holding device are combined with the second signal. , A protection operation is performed by determining whether an AND condition is satisfied with the first signal output within a predetermined time for which the hold device holds the second signal output from the current change amount detection device at the inverse converter end. Since it is configured to perform a protection operation of the DC transmission line by a protection operation signal output from the determination means, and a determination means for outputting a signal,
It is possible to obtain a protective relay device for a DC transmission line that effectively protects a DC transmission system without misjudging a commutation failure of an inverse converter as a DC line accident.

According to the invention of claim 7, the output of the first signal from the current change rate detecting device at the forward converter end and the output of the second signal from the current change rate detecting device at the inverse converter end. And a determination unit that outputs a protection operation signal on the condition that the voltage change rate detection device detects that the voltage change rate of the DC voltage of the DC transmission line is equal to or higher than a certain level, and the determination unit outputs the protection operation signal. Since the protection operation signal of the output is used to perform the protection operation of the DC transmission line, the DC transmission line effectively protects the DC transmission system without erroneously determining the commutation failure of the inverse converter as the DC line accident. There is an effect that the protective relay device of is obtained.

According to the invention of claim 8, the output of the first signal from the current change amount detecting device at the forward converter end and the output of the second signal from the current change amount detecting device at the inverse converter end. And a voltage change rate detection device, and a determination means for outputting a protection operation signal on condition that the voltage change rate of the DC voltage of the DC power transmission line is detected to be equal to or higher than a certain value is established, and output from the determination means. Since the protection operation signal is configured to perform the protection operation of the DC transmission line, the DC transmission line that effectively protects the DC transmission system without misjudging the commutation failure of the inverse converter as the DC line accident There is an effect that a protective relay device can be obtained.

[Brief description of drawings]

FIG. 1 is a system diagram showing a configuration of a DC power transmission line protective relay device using a DC power transmission line protective relay method according to an embodiment of the present invention.

FIG. 2 is a flow chart showing an operation of a DC power transmission line protective relay method and a DC power transmission line protective relay device using the method, which is an embodiment of the inventions of claims 1 and 5;

FIG. 3 is a system diagram showing a configuration of a DC power transmission line protective relay device in which the DC power transmission line protective relay method according to an embodiment of the present invention is used.

FIG. 4 is a system diagram showing a configuration of a DC power transmission line protective relay device using the DC power transmission line protective relay method according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a protective relay operation of a protective relay device for a DC transmission line using the method for protecting a DC transmission line according to an embodiment of the present invention.

FIG. 6 is a system diagram showing a configuration of a DC power transmission line protective relay device in which the DC power transmission line protective relay method according to an embodiment of the present invention is used.

FIG. 7 is a waveform diagram showing changes in DC current and DC voltage on the forward converter side and the inverse converter side when a DC line fault occurs in a DC power transmission system.

FIG. 8 is a waveform diagram showing changes in DC current and DC voltage on the forward converter side and the inverse converter side when commutation fails in the DC power transmission system.

FIG. 9 is a system diagram showing a configuration of a conventional DC relay protection relay device.

[Explanation of symbols]

1 forward converter, 2 inverse converter, 9, 10 DC transmission line,
21, 31, 53 Protection relay device, 7, 8 DC current detector, 22 Forward converter side current change rate detection device, 23 Inverse converter side current change rate detection device (current change rate detection device),
24, 35 Forward converter side hold device, 25, 37 Reverse converter side hold device (hold device), 26, 34
Forward converter side current change pattern determination device, 27, 36 Inverse converter side current change pattern determination device, 29, 38, 4
2, 52 accident determination device (determination means), 32 forward converter side current change amount detection device, 33 reverse converter side current change amount detection device (current change amount detection device), 40 DC voltage detector, 41 voltage change rate Detection device.

Claims (8)

[Claims] 1. A failure of a DC transmission system in which AC power is converted into DC power by a forward converter, which is transmitted to a receiving end via a DC transmission line, and which is converted back into AC power by an inverse converter at the receiving end. Is detected based on the voltage or current of the DC transmission line,
In a protection relay method for a DC transmission line that protects a DC transmission system in which a failure has occurred, a predetermined value after the current of the DC transmission line at the forward converter end increases at a current change rate of a certain magnitude or more. Within a predetermined time after the current change rate decreases by a certain magnitude or more within a time, and the current of the DC transmission line at the inverse converter end decreases by a current change rate of a certain magnitude or more. In addition, when the current change rate increases by a certain magnitude or more, it is determined that the DC power transmission line has a failure, and the DC power transmission system protection operation is performed. 2. A failure of a DC power transmission system in which AC power is converted to DC power by a forward converter, which is transmitted to a power receiving end via a DC power transmission line, and which is converted back to AC power by an inverse converter at the power receiving end. Is detected based on the voltage or current of the DC transmission line,
In a protective relay method for a DC transmission line that protects a DC transmission system in which a failure has occurred, a predetermined time after the current of the DC transmission line at the forward converter end has increased by a change amount of a certain magnitude or more. Within a predetermined time after the amount of change in the current decreases by a certain amount or more, and the current of the DC transmission line at the inverse converter end decreases by a certain amount of change or more A protection relay method for a DC power transmission line, comprising determining that the DC power transmission line has a failure when the amount of change in the current increases by a certain magnitude or more, and shifting to a protection operation of the DC power transmission system. 3. A failure of a DC power transmission system in which AC power is converted to DC power by a forward converter, which is transmitted to a receiving end via a DC transmission line, and which is converted back to AC power by an inverse converter at the receiving end. Is detected based on the voltage or current of the DC transmission line,
In a protective relay method for a DC power transmission line that protects a DC power transmission system in which a failure has occurred, the current of the DC power transmission line at the end of the forward converter increases at a certain rate of change or more, and the reverse conversion is performed. Failure of the DC transmission line when the current of the DC transmission line at the end of the equipment decreases at a rate of change above a certain magnitude and the DC voltage of the DC transmission line changes at a rate of voltage change above a certain level. The protection relay method of the DC power transmission line, characterized in that the protection operation of the DC power transmission system is performed. 4. A failure of a DC power transmission system in which AC power is converted into DC power by a forward converter, which is transmitted to a receiving end via a DC transmission line, and which is converted back into AC power by an inverse converter at the receiving end. In the protection relay method of the DC transmission line, which detects the voltage and current of the DC transmission line based on the voltage or current of the DC transmission line to protect the DC transmission system in which a failure has occurred, the current of the DC transmission line at the forward converter end is constant. Of the DC power transmission line at the end of the inverse converter, the current of the DC transmission line at the end of the inverse converter decreases by a change of more than a certain level, and the DC voltage of the DC power transmission system is more than a certain level. The method of protection relay of a DC power transmission line, characterized in that the DC power transmission line is determined to be faulty when the voltage change rate changes, and the DC power transmission system protection operation is performed. 5. A failure of a DC power transmission system in which AC power is converted to DC power by a forward converter, which is transmitted to a power receiving end via a DC power transmission line, and which is converted back to AC power by an inverse converter at the power receiving end. In the protective relay device of the DC power transmission line for protecting the DC power transmission system in which a failure has occurred, the forward relay end and the inverse converter end of the DC power transmission line are respectively provided,
The rate of change of the current of the DC transmission line is detected, and when the current increases at a rate of change equal to or higher than a certain level, a first signal is output. A current change rate detection device that outputs a second signal when it decreases, a hold device that holds the first signal or the second signal for a certain period of time, and the current change rate detection device at the forward converter end. From the first signal is output from the holding device, the holding device holds the first signal within a predetermined time, the second signal output;
After the second signal is output from the current change rate detection device at the inverse converter end, the first signal output within a predetermined time during which the hold device holds the second signal. And a determination means for determining whether the AND condition is satisfied and outputting a protection operation signal, and the determination means outputs a protection operation signal for performing a protection operation of the DC power transmission system. Protective relay device. 6. A failure of a DC transmission system in which AC power is converted to DC power by a forward converter, which is transmitted to a power receiving end via a DC power transmission line, and which is converted back to AC power by an inverse converter at the power receiving end. In the protective relay device of the DC power transmission line for protecting the DC power transmission system in which a failure has occurred, the forward relay end and the inverse converter end of the DC power transmission line are respectively provided,
The amount of change in the current of the DC transmission line is detected, a first signal is output when the amount of change in the current increases by a certain amount or more, and the amount of change in the amount of change in the certain amount or more changes the current. A current change amount detection device that outputs a second signal when it decreases, a hold device that holds the first signal or the second signal for a certain period of time, and the current change amount detection device at the forward converter end. From the first signal is output from the holding device, the holding device holds the first signal within a predetermined time, the second signal output;
After the second signal is output from the current change amount detection device at the inverse converter end, the first signal output within a predetermined time during which the hold device holds the second signal. And a determination means for determining whether the AND condition is satisfied and outputting a protection operation signal, and the determination means outputs a protection operation signal for performing a protection operation of the DC power transmission system. Protective relay device. 7. A failure of a DC power transmission system in which AC power is converted to DC power by a forward converter, which is transmitted to a power receiving end via a DC power transmission line, and which is converted back to AC power by an inverse converter at the power receiving end. In the protective relay device of the DC power transmission line for protecting the DC power transmission system in which a failure has occurred, the forward relay end and the inverse converter end of the DC power transmission line are respectively provided,
The rate of change of the current of the DC transmission line is detected, and when the current increases at a rate of change equal to or higher than a certain level, a first signal is output. When it decreases, a current change rate detection device that outputs a second signal, a voltage change rate detection device that detects a change rate of the DC voltage of the DC transmission system, and a current change rate detection device at the forward converter end An output of the first signal of
The output of the second signal from the current change rate detection device and the voltage change rate detection device detected a voltage change rate of a certain level or more of the DC voltage of the DC transmission system at the inverse converter end. A protection circuit for outputting a protection operation signal on condition that both are established, and a protection operation signal for performing a protection operation of the DC transmission system is output from the judgment means. Relay device. 8. A failure in a DC power transmission system in which AC power is converted to DC power by a forward converter, which is transmitted to a receiving end via a DC transmission line, and which is converted back to AC power by an inverse converter at the receiving end. In the protective relay device of the DC power transmission line for protecting the DC power transmission system in which a failure has occurred, the forward relay end and the inverse converter end of the DC power transmission line are respectively provided,
The amount of change in the current of the DC transmission line is detected, a first signal is output when the amount of change in the current increases by a certain amount or more, and the amount of change in the amount of change in the certain amount or more changes the current. From the current change amount detection device that outputs a second signal when it decreases, the voltage change rate detection device that detects the change rate of the DC voltage of the DC transmission system, and the current change amount detection device at the forward converter end. An output of the first signal of
The output of the second signal from the current change amount detection device at the inverse converter end and the voltage change rate detection device detect a voltage change rate of a certain level or more of the DC voltage of the DC transmission system. A protection circuit for outputting a protection operation signal on condition that both are established, and a protection operation signal for performing a protection operation of the DC transmission system is output from the judgment means. Relay device.