CN109946569B - Method and device for detecting exit risk of direct current filter and direct current power transmission system - Google Patents
Method and device for detecting exit risk of direct current filter and direct current power transmission system Download PDFInfo
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Abstract
The invention discloses a method and equipment for detecting exit risk of a direct current filter and a direct current power transmission system, wherein the method comprises the following steps: detecting current flowing through the rest running direct current filters after the fault direct current filters which quit running appear in the direct current power transmission system; solving an effective value of the current, and comparing the effective value of the current with a preset current threshold; and when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate. Therefore, after the fault direct current filter which quits from operation appears in the direct current power transmission system, the effective value of the current flowing through other normal direct current filters is obtained, and when the effective value of the current is overlarge, the fault direct current filter is considered to have safety risk when the direct current normally operates, so that a worker can conveniently make corresponding safety measures in time after referring to the detected system safety risk condition, and the power supply safety and reliability of the system are improved.
Description
Technical Field
The invention relates to the field of direct current power transmission, in particular to a method and equipment for detecting exit risk of a direct current filter and a direct current power transmission system.
Background
At present, in a direct current transmission system, a direct current filter is widely applied, and is mainly used for filtering characteristic harmonic waves generated by phase change of a converter station (including a rectifier station and an inverter station). Referring to fig. 1, fig. 1 is a schematic structural diagram of a dc power transmission system in the prior art. In fig. 1, a power supply end is provided with a rectifying station, a power utilization end is provided with an inverter station, and the working principle is as follows: alternating current output by the alternating current power supply is input into the rectifying station, the rectifying station rectifies the alternating current and then outputs direct current, so that electric energy is transmitted in a direct current mode in a power transmission line, and when the direct current is transmitted to the inverter station, the inverter station inverts the direct current and then outputs the alternating current to supply power for power utilization equipment.
In the running process of the direct-current power transmission system, it is a common fault that the direct-current filter is out of operation after abnormality occurs. In the prior art, the dc filter usually keeps the dc normal operation for a period of time (e.g. 2 hours) after the abnormality occurs, and then latches the dc. However, for different dc power transmission systems, the safety of the dc power transmission system that continues to operate after the dc filter exits from operating is different, and if the dc power transmission system with the safety risk continues to operate after the dc filter exits from operating, the power supply safety and reliability of the dc power transmission system may be reduced.
Therefore, how to provide a system risk detection method after the dc filter is out of operation is a problem that needs to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to provide a method and equipment for detecting exit risk of a direct current filter and a direct current transmission system, which can detect the safety risk condition of the system after any direct current filter exits from operation, so that a worker can conveniently make corresponding safety measures in time after referring to the detected safety risk condition of the system, and the power supply safety and reliability of the direct current transmission system are improved.
In order to solve the above technical problem, the present invention provides a method for detecting an exit risk of a dc filter, including:
detecting current flowing through the rest running direct current filters after the fault direct current filters which quit running appear in the direct current power transmission system;
calculating an effective value of the current, and comparing the effective value of the current with a preset current threshold;
and when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
Preferably, the exit risk detection method further comprises:
detecting whether a direct current signal sampled by a control host for controlling the current conversion operation of a converter station in the direct current transmission system is subjected to low-pass filtering or not;
and if not, determining that the fault direct current filter has safety risk when the normal operation of direct current is kept.
Preferably, the detecting is to detect whether a dc current signal sampled by a control host for controlling a converter operation of a converter station in the dc power transmission system is low-pass filtered; if not, determining that the fault direct current filter has a safety risk when the fault direct current filter keeps normal operation of direct current, wherein the process comprises the following steps:
detecting whether a sampling front end of a control host for controlling the current conversion operation of a current conversion station in the direct current transmission system is connected with a low-pass filter or not;
if the low-pass filter is not connected, detecting whether a built-in program of the control host computer comprises a sampling signal low-pass filtering program; and if not, determining that the fault direct current filter has safety risk when the normal operation of direct current is kept.
Preferably, the exit risk detection method further comprises:
detecting whether a direct current signal sampled by a protection host for controlling the emergency shutdown of the direct current power transmission system is subjected to low-pass filtering or not;
and if not, determining that the fault direct current filter has safety risk when the normal operation of direct current is kept.
Preferably, the detecting is to detect whether a dc current signal sampled by a protection host for controlling the emergency shutdown of the dc power transmission system is low-pass filtered; if not, determining that the fault direct current filter has a safety risk when the fault direct current filter keeps normal operation of direct current, wherein the process comprises the following steps:
before a fault direct current filter which exits from operation appears in the direct current power transmission system, acquiring a first direct current waveform recorded by a wave recording module from a protection host used for controlling the direct current power transmission system to be in emergency shutdown;
after a fault direct current filter which exits from operation appears in the direct current power transmission system, acquiring a second direct current waveform recorded by the fault direct current filter from the wave recording module;
comparing the first direct current waveform with the second direct current waveform through a preset graph comparison algorithm to obtain a waveform difference value of the first direct current waveform and the second direct current waveform;
and when the waveform difference value is larger than a preset difference threshold value, determining that the fault direct current filter has safety risk when the normal operation of direct current is kept.
Preferably, the exit risk detection method further comprises:
and when the fault direct current filter is determined to have safety risk when the direct current is kept running normally, controlling an alarm device to give an alarm.
Preferably, the alarm device is a sound-light alarm.
In order to solve the above technical problem, the present invention further provides an exit risk detection device for a dc filter, including:
the current detection device is used for detecting the current flowing through the other running direct current filters after the fault direct current filter which is out of operation appears in the direct current power transmission system;
the control device is used for solving the effective value of the current and comparing the effective value of the current with a preset current threshold value; and when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
Preferably, the exit risk detection apparatus further comprises:
the control host detection device is used for detecting whether a direct current signal sampled by a control host for controlling the current conversion operation of a converter station in the direct current transmission system is subjected to low-pass filtering or not; if not, determining that the fault direct current filter has safety risk when the normal operation of direct current is kept;
the protection host detection device is used for detecting whether a direct current signal sampled by a protection host for controlling the emergency shutdown of the direct current transmission system is subjected to low-pass filtering or not; and if not, determining that the fault direct current filter has safety risk when the normal operation of direct current is kept.
In order to solve the technical problem, the invention further provides a direct current power transmission system which comprises the exit risk detection equipment of any one of the direct current filters.
The invention provides a method for detecting exit risk of a direct current filter, which comprises the following steps: detecting current flowing through the rest running direct current filters after the fault direct current filters which quit running appear in the direct current power transmission system; solving an effective value of the current, and comparing the effective value of the current with a preset current threshold; and when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
Considering that after a certain fault direct current filter in the direct current transmission system quits operation, the current flowing through other running direct current filters can be influenced, the effective value of the current flowing through other running direct current filters is obtained, and when the effective value of the current is overlarge, the fault direct current filter is considered to have safety risk when the direct current normally runs, so that a worker can conveniently make corresponding safety measures in time after referring to the detected system safety risk condition, and the power supply safety and reliability of the direct current transmission system are improved.
The invention also provides exit risk detection equipment of the direct current filter and a direct current power transmission system, and the exit risk detection equipment and the direct current power transmission system have the same beneficial effects as the exit risk detection method.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed in the prior art and the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic diagram of a dc power transmission system according to the prior art;
fig. 2 is a flowchart of an exit risk detection method for a dc filter according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a dc side harmonic circulation path of a dc power transmission system according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a harmonic circulation path on the dc side after the dc filter exits according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an exit risk detection device of a dc filter according to the present invention.
Detailed Description
The core of the invention is to provide a method and equipment for detecting the exit risk of a direct current filter and a direct current transmission system, which can detect the safety risk condition of the system after any direct current filter exits from operation, thereby facilitating the staff to make corresponding safety measures in time after referring to the detected system safety risk condition and further improving the power supply safety and reliability of the direct current transmission system.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 2, fig. 2 is a flowchart illustrating an exit risk detection method for a dc filter according to an embodiment of the present invention.
The exit risk detection method of the direct current filter comprises the following steps:
step S1: after a fault direct current filter which is out of operation appears in the direct current power transmission system, the current flowing in the rest direct current filters which are in operation is detected.
Step S2: and solving the effective value of the current, and comparing the effective value of the current with a preset current threshold value.
Step S3: and when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
Specifically, a circulation path of a characteristic harmonic on a direct current side (mainly the 12 th harmonic content in the characteristic harmonic, in the embodiment of the present application, the 12 th harmonic is analyzed as an example, and other harmonics are analyzed in the same principle) when all direct current filters in a direct current transmission system normally operate is analyzed.
Referring to fig. 3, fig. 3 is a schematic diagram of a dc side harmonic circulation path of a dc power transmission system according to an embodiment of the present invention.
The specific analysis principle of the direct current side harmonic flow path is as follows: analyzing the content and direction of the 12 th harmonic in the dc side current, taking the rectification side pole 1 as an example, it is known that the 12 th harmonic content of A1IDCH, A1DCN, A1Z1T1 is substantially the same and all positive, and the 12 th harmonic content of A1IDLH, A1IDLN is low, so it can be said that the 12 th harmonic of the current in the rectification side pole 1 flows between the converter valve and the dc filter clockwise. Similarly, 12 th harmonic of the current in the rectifying side pole 2, the inverting side pole 1 and the inverting side pole 2 flows between the converter valve and the dc filter clockwise, that is, the dc side harmonic flow path is as shown in fig. 3.
When a certain pole direct current filter in the direct current power transmission system stops operating (namely, the certain pole direct current filter is no longer in electrical connection with direct current), the current flowing through the other operating direct current filters can be changed to a certain extent. If the effective value of the current flowing through the other running direct current filters exceeds a certain threshold (for example, 100A) after the direct current filter of one pole is out of operation, it indicates that the direct current filter has a large influence on the safe operation of the direct current transmission system after being out of operation; otherwise, the direct current filter does not have a great influence on the safe operation of the direct current transmission system after the direct current filter exits from operation.
And then analyzing the specific change condition of the current flowing through the other running direct current filters after the direct current filter of one pole in the direct current power transmission system is out of operation. Referring to fig. 4, fig. 4 is a schematic diagram of a harmonic circulation path on the dc side after the dc filter exits according to an embodiment of the present invention, taking an example of the exit operation of the dc filter of the rectification side pole 1.
The specific analysis principle is as follows: from the dc-side harmonic flow path of fig. 3, it can be derived that after the dc filter of the rectifying side pole 1 is out of operation, the 12 th harmonic of the dc filter that should flow through the rectifying side pole 1 will flow into the rest of the operating dc filters, as shown by the thick straight line in fig. 4, and the direction of the arrow represents the flow direction. Meanwhile, as can be seen from the dc-side harmonic flow path in fig. 3, the rest of the operating dc filters also flow 12 th harmonic waves when the dc filter of the rectification side pole 1 does not exit the operation, as shown by the thin-strip curve in fig. 4. It can be seen that when the dc filter of a certain pole on the rectifying side or the inverting side of the dc power transmission system is out of operation, the effective value and the instantaneous value variation of the current flowing through the remaining operating dc filters depend on the phasor sum of the 12 th harmonic added to the remaining operating dc filters and the original 12 th harmonic.
Based on the analysis result, the current flowing through the rest of the running direct current filters can be detected after the fault direct current filter which is out of operation appears in the direct current transmission system. The effective value of the current is then found and compared to a preset current threshold (set empirically). And when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate. At the moment, in order to ensure the safety of the direct current transmission system, a worker can directly control the direct current filter to block direct current and does not keep the direct current to normally run for a period of time.
It should be noted that the preset of the present application is set in advance, and only needs to be set once, and the reset is not needed unless the modification is needed according to the actual situation.
In addition, considering that the influence of the quitting operation of the direct current filter on other running direct current filters is different under different working conditions, the influence of the quitting operation of the direct current filter on other running direct current filters under different working conditions can be analyzed, and the worst working condition can be obtained (namely the 12-order harmonic wave of the direct current is increased most obviously after the direct current filter quits operation under the working condition).
The invention provides a method for detecting exit risk of a direct current filter, which comprises the following steps: detecting current flowing through the rest running direct current filters after the fault direct current filters which quit running appear in the direct current power transmission system; solving an effective value of the current, and comparing the effective value of the current with a preset current threshold; and when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
Considering that after a certain fault direct current filter in the direct current transmission system quits operation, the current flowing through other running direct current filters can be influenced, the effective value of the current flowing through other running direct current filters is obtained, and when the effective value of the current is overlarge, the fault direct current filter is considered to have safety risk when the direct current normally runs, so that a worker can conveniently make corresponding safety measures in time after referring to the detected system safety risk condition, and the power supply safety and reliability of the direct current transmission system are improved.
On the basis of the above-described embodiment:
as an optional embodiment, the exit risk detection method further comprises:
detecting whether a direct current signal sampled by a control host for controlling the current conversion operation of a converter station in a direct current transmission system is subjected to low-pass filtering or not;
and if not, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
Further, the known dc power transmission system includes a control host for controlling a converter operation of the converter station, and the control host needs to sample a dc current signal filtered by a dc filter in the dc power transmission system during a control process, and if the dc filter stops operating, 12 th order harmonics may be added to the dc current signal sampled by the control host. If the direct current signal sampled by the control host is subjected to low-pass filtering, the 12-order harmonic added in the direct current signal is filtered, and the subsequent control of the control host is not influenced; otherwise, the subsequent control of the control host is affected.
Based on this, according to the method and the device, after the fault direct current filter which exits from operation appears in the direct current power transmission system, whether the direct current signal sampled by the control host in the direct current power transmission system is subjected to low-pass filtering or not can be detected, if the direct current signal is not subjected to low-pass filtering, the direct current filter exits from operation and influences subsequent control of the control host, and then the fault direct current filter is determined to have safety risk when the direct current normal operation is kept.
As an optional embodiment, detecting whether a dc current signal sampled by a control host for controlling a commutation operation of a converter station in a dc power transmission system is low-pass filtered; if not, determining that the fault direct current filter has a safety risk when the fault direct current filter keeps normal operation of direct current, wherein the process comprises the following steps:
detecting whether a sampling front end of a control host for controlling the current conversion operation of a current conversion station in the direct current transmission system is connected with a low-pass filter or not;
if the low-pass filter is not connected, detecting whether a built-in program of the control host computer comprises a sampling signal low-pass filtering program; and if not, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
Specifically, considering that there are two filtering methods for the dc current signal sampled by the control host in the dc power transmission system at present: firstly, a low-pass filter is connected to the sampling front end of a control host; secondly, a low-pass filtering program of the sampling signal is written into a built-in program of the control host. Therefore, when detecting whether the direct current signal sampled by the control host is low-pass filtered or not, firstly detecting whether the sampling front end of the control host is connected with a low-pass filter or not, and if the sampling front end of the control host is connected with the low-pass filter, the direct current filter quits from running and cannot influence the subsequent control of the control host; if the low-pass filter is not connected, detecting whether a built-in program of the control host contains a sampling signal low-pass filtering program or not, and if the sampling signal low-pass filtering program exists, stopping running of the direct-current filter does not affect subsequent control of the control host; if the sampling signal low-pass filtering program is not available, the fact that the direct current filter exits from operation and influences subsequent control of the control host is indicated, and it is determined that the fault direct current filter has safety risks when the direct current filter keeps normal operation.
As an optional embodiment, the exit risk detection method further comprises:
detecting whether a direct current signal sampled by a protection host for controlling the emergency shutdown of the direct current power transmission system is subjected to low-pass filtering or not;
and if not, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
Further, the known dc power transmission system includes a protection host for controlling an emergency shutdown of the dc power transmission system, and the protection host also needs to sample a dc current signal filtered by a dc filter in the dc power transmission system during a protection control process. Similarly, if the dc filter exits operation, 12 th harmonic waves are added to the dc current signal sampled by the protection host. If the direct current signal sampled by the protection host is subjected to low-pass filtering, the 12 th harmonic added in the direct current signal is filtered, and the subsequent protection control of the protection host is not influenced; otherwise, the subsequent protection control of the protection host is affected.
Based on this, the method and the device can also detect whether the direct current signal sampled by the protection host in the direct current transmission system is subjected to low-pass filtering, and if the direct current signal is not subjected to low-pass filtering, the direct current filter exits from operation and can affect the subsequent protection control of the protection host, and the safety risk of the fault direct current filter in keeping the direct current normal operation is determined.
As an alternative embodiment, detecting whether a dc current signal sampled by a protection host for controlling an emergency shutdown of a dc power transmission system is low-pass filtered; if not, determining that the fault direct current filter has a safety risk when the fault direct current filter keeps normal operation of direct current, wherein the process comprises the following steps:
before a fault direct-current filter which exits from operation appears in a direct-current power transmission system, acquiring a first direct-current waveform recorded by a wave recording module from a protection host used for controlling the direct-current power transmission system to be stopped emergently;
after a fault direct current filter which exits from operation appears in the direct current power transmission system, a second direct current waveform recorded by the fault direct current filter is obtained from the wave recording module;
comparing the first direct current waveform with the second direct current waveform through a preset graph comparison algorithm to obtain a waveform difference value of the first direct current waveform and the second direct current waveform;
and when the waveform difference value is larger than a preset difference threshold value, determining that the fault direct current filter has safety risk when the normal operation of direct current is kept.
Specifically, it is considered that the protection host of the dc power transmission system includes a wave recording module, and the wave recording module can record the waveform of the dc current signal sampled by the protection host, so the present application can obtain the waveform of the dc current signal sampled by the protection host at this time (referred to as a first dc waveform) from the wave recording module before the dc power transmission system has the faulty dc filter that exits from operation, and then obtain the waveform of the dc current signal sampled by the protection host at this time (referred to as a second dc waveform) from the wave recording module after the dc power transmission system has the faulty dc filter that exits from operation.
It can be understood that if the difference between the first direct current waveform and the second direct current waveform is small, the direct current signal sampled by the protection host is considered to be subjected to low-pass filtering; if the difference is large, it can be considered that the direct current signal sampled by the protection host has not undergone low pass filtering. Therefore, the method and the device utilize a graph comparison algorithm to perform waveform comparison on the first direct current waveform and the second direct current waveform to obtain waveform difference values of the first direct current waveform and the second direct current waveform, then the waveform difference values are compared with a preset difference threshold value, when the waveform difference values are larger than the preset difference threshold value, it is indicated that a direct current signal sampled by a protection host does not undergo low-pass filtering, namely the direct current filter retreats from running to influence subsequent protection control of the protection host, and then it is determined that a safety risk exists when the fault direct current filter keeps normal operation of direct current.
As an optional embodiment, the exit risk detection method further comprises:
and when the fault direct current filter is determined to have safety risk when the direct current is kept to normally operate, controlling an alarm device to give an alarm.
Furthermore, the method and the device can control the alarm device to give an alarm when the fault direct current filter is determined to have safety risks in the direct current normal operation, so that a worker is reminded that the fault direct current filter continues to keep the direct current normal operation, the direct current power transmission system can have safety risks, and the worker can make corresponding safety measures in time.
As an alternative embodiment, the alarm device is embodied as an audible and visual alarm.
Specifically, the alarm device of the present application may be selected from, but not limited to, audible and visual alarms (acoustic signal + optical signal), and the present application is not limited thereto.
Referring to fig. 5, fig. 5 is a schematic structural diagram of an exit risk detection apparatus of a dc filter according to the present invention.
The exit risk detection device of the direct current filter comprises:
the current detection device 1 is used for detecting the current flowing through the rest running direct current filters after the fault direct current filters which quit running appear in the direct current power transmission system;
the control device 2 is used for solving an effective value of the current and comparing the effective value of the current with a preset current threshold; and when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
As an optional embodiment, the exit risk detection device further comprises:
the control host detection device is used for detecting whether a direct current signal sampled by a control host for controlling the current conversion operation of a converter station in the direct current transmission system is subjected to low-pass filtering or not; if not, determining that the fault direct current filter has safety risk when the direct current is kept running normally;
the protection host detection device is used for detecting whether a direct current signal sampled by a protection host for controlling the emergency shutdown of the direct current transmission system is subjected to low-pass filtering or not; and if not, determining that the fault direct current filter has safety risk when the direct current is kept to normally operate.
For introduction of the exit risk detection device provided by the present invention, reference is made to the above-mentioned embodiment of the exit risk detection method, and the present invention is not described herein again.
The invention also provides a direct current power transmission system which comprises the exit risk detection equipment of any one of the direct current filters.
For introduction of the dc power transmission system provided by the present invention, please refer to the above-mentioned embodiment of the exit risk detection device, and the present invention is not described herein again.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method for detecting exit risk of a DC filter is characterized by comprising the following steps:
detecting current flowing through the rest running direct current filters after the fault direct current filters which quit running appear in the direct current power transmission system;
calculating an effective value of the current, and comparing the effective value of the current with a preset current threshold;
and when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current transmission system keeps direct current normal operation.
2. The exit risk detection method of a dc filter according to claim 1, further comprising:
detecting whether a direct current signal sampled by a control host for controlling the current conversion operation of a converter station in the direct current transmission system is subjected to low-pass filtering or not;
and if not, determining that the fault direct current filter has safety risk when the direct current transmission system keeps direct current normal operation.
3. The exit risk detection method of a dc filter according to claim 2, characterized by detecting whether a dc current signal sampled by a control master for controlling a commutation operation of a converter station in said dc power transmission system is low-pass filtered; if not, determining that the fault direct current filter has a safety risk when the direct current transmission system keeps direct current normal operation, including:
detecting whether a sampling front end of a control host for controlling the current conversion operation of a current conversion station in the direct current transmission system is connected with a low-pass filter or not;
if the low-pass filter is not connected, detecting whether a built-in program of the control host computer comprises a sampling signal low-pass filtering program; and if not, determining that the fault direct current filter has safety risk when the direct current transmission system keeps direct current normal operation.
4. The exit risk detection method of the dc filter according to claim 2, further comprising:
detecting whether a direct current signal sampled by a protection host for controlling the emergency shutdown of the direct current power transmission system is subjected to low-pass filtering or not;
and if not, determining that the fault direct current filter has safety risk when the direct current transmission system keeps direct current normal operation.
5. The exit risk detection method of a dc filter according to claim 4, characterized in that said detecting is performed to detect whether a dc current signal sampled by a protection master for controlling an emergency shutdown of said dc power transmission system is low-pass filtered; if not, determining that the fault direct current filter has a safety risk when the direct current transmission system keeps direct current normal operation, including:
before a fault direct current filter which exits from operation appears in the direct current power transmission system, acquiring a first direct current waveform recorded by a wave recording module from a protection host used for controlling the direct current power transmission system to be in emergency shutdown;
after a fault direct current filter which exits from operation appears in the direct current power transmission system, acquiring a second direct current waveform recorded by the fault direct current filter from the wave recording module;
comparing the first direct current waveform with the second direct current waveform through a preset graph comparison algorithm to obtain a waveform difference value of the first direct current waveform and the second direct current waveform;
and when the waveform difference value is larger than a preset difference threshold value, determining that the fault direct-current filter has a safety risk when the direct-current transmission system keeps direct-current normal operation.
6. The exit risk detection method of the dc filter according to any of claims 1 to 5, characterized in that the exit risk detection method further comprises:
and when the fault direct current filter is determined to have safety risk when the direct current transmission system keeps direct current normal operation, controlling an alarm device to give an alarm.
7. The exit risk detection method of a dc filter according to claim 6, characterized in that said alarm means is in particular an audible and visual alarm.
8. An exit risk detection apparatus of a direct current filter, comprising:
the current detection device is used for detecting the current flowing through the other running direct current filters after the fault direct current filter which is out of operation appears in the direct current power transmission system;
the control device is used for solving the effective value of the current and comparing the effective value of the current with a preset current threshold value; and when the effective value of the current is larger than the preset current threshold value, determining that the fault direct current filter has safety risk when the direct current transmission system keeps direct current normal operation.
9. An exit risk detection device of a dc filter according to claim 8, characterized in that the exit risk detection device further comprises:
the control host detection device is used for detecting whether a direct current signal sampled by a control host for controlling the current conversion operation of a converter station in the direct current transmission system is subjected to low-pass filtering or not; if not, determining that the fault direct current filter has a safety risk when the direct current transmission system keeps direct current normal operation;
the protection host detection device is used for detecting whether a direct current signal sampled by a protection host for controlling the emergency shutdown of the direct current transmission system is subjected to low-pass filtering or not; and if not, determining that the fault direct current filter has safety risk when the direct current transmission system keeps direct current normal operation.
10. A direct current power transmission system, characterized by an exit risk detection device comprising a direct current filter according to any of claims 8-9.
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