CN114374193B - Active detection type power distribution network protection method based on action delay - Google Patents
Active detection type power distribution network protection method based on action delay Download PDFInfo
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- CN114374193B CN114374193B CN202111489437.2A CN202111489437A CN114374193B CN 114374193 B CN114374193 B CN 114374193B CN 202111489437 A CN202111489437 A CN 202111489437A CN 114374193 B CN114374193 B CN 114374193B
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Abstract
The invention provides an active detection type power distribution network protection method based on action delay, which comprises the following steps: acquiring alternating voltage passing through controllable power electronic equipment, and judging that the power distribution network fails when the alternating voltage is smaller than a preset limit value; acquiring a positive sequence fault component of the power distribution network, and judging whether a protection starting condition is met or not according to the positive sequence fault component; if the protection starting condition is met, an active detection signal is sent to protection equipment in the power distribution network through controllable power electronic equipment; and determining the action delay of the protection equipment according to the electrical distance between the protection equipment and the controllable power electronic equipment, and controlling the protection equipment to perform protection action based on the action delay. According to the invention, no additional equipment is required, and the problem of insufficient current protection sensitivity caused by the weak feedback characteristic of the power electronic equipment can be solved on the premise that the normal operation of other irrelevant equipment of the power distribution network is not influenced.
Description
Technical Field
The invention belongs to the technical field of power systems, and particularly relates to an active detection type power distribution network protection method based on action delay.
Background
With the application of high-proportion renewable energy sources in an electric power system, the influence on the structure of a power distribution network is greatly changed. The current power distribution network is usually in a structure of mixed direct current and alternating current, one side is an alternating current system, the other side is a direct current system, and the alternating current and direct current conversion is realized through controllable power electronic equipment such as an inverter and the like. However, the weak feedback characteristic of the controllable power electronic device can cause the problems of small outlet current, insufficient current protection sensitivity and the like.
At present, protection schemes of a power distribution network aiming at the problems are divided into two types, one is to apply the protection scheme of a power transmission network to the power distribution network, and the other is to adopt new algorithms such as self-adaption, directional element addition and the like based on the current protection configuration. The first type of method relies on communication and is relatively costly. The second method mainly introduces voltage quantity, has new problems of complex wiring, voltage dead zone and the like, and reduces the sensitivity of power distribution network protection.
Disclosure of Invention
In order to solve the defects and shortcomings in the prior art, the invention provides an active detection type power distribution network protection method based on action delay, which comprises the following steps:
Acquiring alternating voltage passing through controllable power electronic equipment, and judging that the power distribution network fails when the alternating voltage is smaller than a preset limit value;
acquiring a positive sequence fault component of the power distribution network, and judging whether a protection starting condition is met or not according to the positive sequence fault component;
if the protection starting condition is met, an active detection signal is sent to protection equipment in the power distribution network through controllable power electronic equipment;
When the protection equipment receives the active detection signal, the action delay of the protection equipment is determined according to the electrical distance between the protection equipment and the controllable power electronic equipment, and the protection equipment is controlled to make protection action based on the action delay.
Optionally, the preset limit value is 70% of rated voltage of the power distribution network alternating current system.
Optionally, the obtaining the positive sequence fault component of the power distribution network, and judging whether the protection starting condition is met according to the positive sequence fault component, includes:
and acquiring a voltage component and a current component in the positive sequence fault component, calculating a phase difference between the voltage component and the current component, and judging that the protection starting condition is met when the phase difference is between-180 DEG and 180 deg.
Optionally, if the protection start condition is met, sending, by the controllable power electronic device, an active detection signal to a protection device in the power distribution network, including:
When the protection starting condition is met, superposing a phase jump trigger signal on an original control signal of the input end of the controllable power electronic equipment;
The switching-off of a switching element in the controllable power electronic equipment is controlled through a phase jump trigger signal, so that the phase jump of an output signal of the controllable converter occurs;
And sending the output signal with the phase jump to protection equipment in the power distribution network as an active detection signal.
Optionally, when the protection device receives the active detection signal, determining an action delay of the protection device according to an electrical distance between the protection device and the controllable power electronic device, and controlling the protection device to make a protection action based on the action delay, including:
determining the position of the protection equipment receiving the active detection signal in the power distribution network, and acquiring the electrical distance between the protection equipment and the controllable power electronic equipment by combining the position of the controllable power electronic equipment sending the active detection signal;
determining action delay corresponding to the electrical distance according to a preset inverse time limit action curve;
and according to the change condition of the phase jump variable of the line where the protection equipment receives the active detection signal, the protection equipment is controlled to make protection action by combining action delay.
Optionally, the step of controlling the protection device to perform a protection action in combination with action delay according to a change condition of a phase jump variable of a line where the protection device receives the active detection signal includes:
the protection equipment makes protection actions according to the action delay sequence, and when each protection action response is finished, the change condition of the phase jump variable of the line where the protection equipment which does not make the protection actions is located is detected respectively;
and if the phase jump variable is reduced to the preset amount, stopping the protection action of the protection equipment, otherwise, continuously controlling the protection equipment to make the protection action according to the action delay sequence.
The technical scheme provided by the invention has the beneficial effects that:
The method has the advantages that no additional equipment is needed, communication is not needed, the method is simple and convenient to realize, and the problem of insufficient current protection sensitivity caused by the weak feed characteristic of the power electronic equipment can be solved on the premise that normal operation of other irrelevant equipment of the power distribution network is not affected.
Drawings
In order to more clearly illustrate the technical solutions of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic flow chart of an active detection type power distribution network protection method based on action delay according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a typical structure of an ac/dc hybrid power distribution network;
fig. 3 is an inverse time-lapse action graph for setting an action delay.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terms "first," "second," "third," "fourth" and the like in the description and in the claims and in the above drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein.
It should be understood that, in various embodiments of the present invention, the sequence number of each process does not mean that the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.
It should be understood that in the present invention, "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements that are expressly listed or inherent to such process, method, article, or apparatus.
It should be understood that in the present invention, "plurality" means two or more. "and/or" is merely an association relationship describing an association object, and means that three relationships may exist, for example, and/or B may mean: a exists alone, A and B exist together, and B exists alone. The character "/" generally indicates that the context-dependent object is an "or" relationship. "comprising A, B and C", "comprising A, B, C" means that all three of A, B, C are comprised, "comprising A, B or C" means that one of A, B, C is comprised, "comprising A, B and/or C" means that any 1 or any 2 or 3 of A, B, C are comprised.
It should be understood that in the present invention, "B corresponding to a", "a corresponding to B", or "B corresponding to a" means that B is associated with a, from which B can be determined. Determining B from a does not mean determining B from a alone, but may also determine B from a and/or other information. The matching of A and B is that the similarity of A and B is larger than or equal to a preset threshold value.
As used herein, the term "if" may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context.
The technical scheme of the invention is described in detail below by specific examples. The following embodiments may be combined with each other, and some embodiments may not be repeated for the same or similar concepts or processes.
Example 1
As shown in fig. 1, this embodiment proposes an active detection type power distribution network protection method based on action delay, including:
S1: acquiring alternating voltage passing through controllable power electronic equipment, and judging that the power distribution network fails when the alternating voltage is smaller than a preset limit value;
s2: acquiring a positive sequence fault component of the power distribution network, and judging whether a protection starting condition is met or not according to the positive sequence fault component;
S3: if the protection starting condition is met, an active detection signal is sent to protection equipment in the power distribution network through controllable power electronic equipment;
S4: when the protection equipment receives the active detection signal, the action delay of the protection equipment is determined according to the electrical distance between the protection equipment and the controllable power electronic equipment, and the protection equipment is controlled to make protection action based on the action delay.
The controllable power electronic equipment refers to equipment for realizing alternating current-direct current conversion by adopting a power electronic technology, and comprises equipment such as a rectifier bridge, an inverter, a power electronic switch and the like. In the embodiment, on one hand, the problems that the weak feedback characteristic of controllable power electronic equipment will cause smaller outlet current, insufficient current protection sensitivity and the like are considered, and on the other hand, the flexible and controllable characteristic of more and more power electronic equipment in the power distribution network is considered, so that the embodiment proposes an active detection power distribution network protection method with definite characteristics, more sensitive and reliable structure, for generating an active detection signal after a system fails.
In this embodiment, taking the typical structure of the ac/dc hybrid power distribution network shown in fig. 2 as an example, the left side is an ac system, the right side is a dc system, the ac/dc system is connected by two 10kV ac dedicated lines, one is connected to a 220kV ac transformer station and a converter station a, and the other is connected to a 110kV transformer station and a converter station B. The converter station A and the converter station B are connected to the same direct current bus to supply power to the direct current load. As can be seen from the 10kV ac private lines L1, L2, L3 in fig. 2, there are also a plurality of ac outgoing lines of the 110kV substation.
In this embodiment, a 10kV ac private line is taken as an example, and it should be noted that the active detection protection method for a power distribution network provided in this embodiment is mainly aimed at faults occurring in an ac system in the power distribution network. Firstly, taking low voltage and direction elements in a power distribution network line as judging conditions for fault occurrence and protection starting, setting a preset limit value in S1 as 70% of rated voltage of an alternating current system of the power distribution network, considering that the power distribution network has faults when the alternating current voltage measured by a converter station B is lower than 70% of the rated voltage, and judging whether the faults occur in the alternating current system according to positive sequence fault components of the power distribution network. I.e. when the distribution network meets the criterionWhen the method is started, the active detection type power distribution network protection method is provided. Wherein U ac is the alternating voltage measured by the converter station B, U n is the rated voltage of the alternating system of the power distribution network, argRepresenting the phase difference between the voltage component deltau 1 and the current component deltai 1 in the positive sequence fault component.
Centering on the converter B in fig. 2, when a front fault, i.e., an ac system fault, occurs, the positive sequence impedance seen at the converter station B is a negative impedance; when a backside fault, i.e. a direct current system fault, occurs, the positive sequence impedance seen at the converter station B is a positive impedance. Therefore, the above criteria can be used for verifying that the distribution network has a fault and the alternating current system on the left side of the converter station B is in fault, so that the active detection type distribution network protection method is started.
After the active detection type power distribution network protection method is started, the converter transformer B is switched to a preset additional control strategy, and the additional control strategy is specifically as follows:
When the protection starting condition is met, superposing a phase jump trigger signal on an original control signal of the input end of the controllable power electronic equipment;
The switching element in the controllable power electronic equipment is controlled to be turned off through the phase jump trigger signal, so that the output signal of the controllable converter is subjected to phase jump, and the phase jump is taken by 90 degrees in the embodiment for facilitating detection on the premise that the normal operation of the power distribution network alternating current system is not influenced.
And sending the output signal with the phase jump to protection equipment in the power distribution network as an active detection signal.
The active detection signal generated by the converter station B can cause the phase jump of the electric signal in the L1 line where the protection devices K1, K2 and K3 are located, so that the protection devices K1, K2 and K3 can sensitively sense the occurrence of faults and make corresponding protection actions.
In order to ensure that the protection action of the protection device does not affect the normal operation of the ac line unrelated to the fault, in this embodiment, a corresponding action delay is set for each protection device that receives the active detection signal, which specifically includes:
Determining the position of the protection equipment receiving the active detection signal in the power distribution network, and combining the position of the controllable power electronic equipment sending the active detection signal; and determining action delay corresponding to the electrical distance according to a preset inverse time limit action curve. In this embodiment, the action delay is specifically determined according to a preset inverse time limit action curve shown in fig. 3, and it can be seen from fig. 3 that a position of the protection device, which is electrically close to the converter station B as the signal transmission source, adopts a larger action delay, and a position of the protection device, which is electrically far from the converter station B, adopts a smaller action delay.
The embodiment is based on the action delay control protection device to make a protection action, specifically, according to the change condition of the phase jump quantity of the line where the protection device receives the active detection signal, the protection action is made by combining the action delay control protection device, and the method specifically includes:
the protection equipment makes protection actions according to the action delay sequence, and when each protection action response is finished, the change condition of the phase jump variable of the line where the protection equipment which does not make the protection actions is located is detected respectively;
and if the phase jump variable is reduced to the preset amount, stopping the protection action of the protection equipment, otherwise, continuously controlling the protection equipment to make the protection action according to the action delay sequence.
Taking L1 in fig. 2 as an example, a protection zone is defined centering on the converter station B, f 1 denotes an out-of-zone fault for the converter station B, and f 2 denotes an in-zone fault for the converter station B. If the fault is an out-of-zone fault, that is, the fault occurs at the f 1, the K1, the K2 and the K3 can detect obvious phase jump, at the moment, the K1 acts before the K2 and the K3, after the K1 breaker is successfully tripped, the voltage at the K2 and the K3 is reduced, and the phase jump variable phase difference at the L1 is supposed to be reduced to a preset amount, so that the K2 and the K3 do not perform protection actions at the follow-up time, and the protection flow is ended, and the fault generated in the alternating current system is tripped through the K1 to realize fault isolation. If the fault is in the area, namely the fault occurs at the position f 2, the fault is influenced by the shunt effect of the fault branch, the phase detected by the K1 hardly changes, so the K1 does not make a protection action, the area irrelevant to the fault at the position f 2 can be ensured to normally operate, the K2 and the K3 detect obvious phase changes, and as the K3 is closer to the converter station B than the K2, the K3 firstly breaks away after a shorter action delay, and the K2 breaks away according to the traditional overcurrent protection after a longer action delay, so that fault isolation is completed.
The various numbers in the above embodiments are for illustration only and do not represent the order of assembly or use of the various components.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof, but rather, the present invention is to be construed as limited to the appended claims.
Claims (4)
1. An active detection type power distribution network protection method based on action delay is characterized by comprising the following steps:
Acquiring alternating voltage passing through controllable power electronic equipment, and judging that the power distribution network fails when the alternating voltage is smaller than a preset limit value;
acquiring a positive sequence fault component of the power distribution network, and judging whether a protection starting condition is met or not according to the positive sequence fault component;
if the protection starting condition is met, an active detection signal is sent to protection equipment in the power distribution network through controllable power electronic equipment;
When the protection equipment receives the active detection signal, determining action delay of the protection equipment according to the electrical distance between the protection equipment and the controllable power electronic equipment, and controlling the protection equipment to perform protection action based on the action delay;
When the protection equipment receives the active detection signal, determining action delay of the protection equipment according to the electrical distance between the protection equipment and the controllable power electronic equipment, and controlling the protection equipment to perform protection action based on the action delay, wherein the method comprises the following steps:
determining the position of the protection equipment receiving the active detection signal in the power distribution network, and acquiring the electrical distance between the protection equipment and the controllable power electronic equipment by combining the position of the controllable power electronic equipment sending the active detection signal;
determining action delay corresponding to the electrical distance according to a preset inverse time limit action curve;
According to the change condition of the phase jump variable of the line where the protection equipment receives the active detection signal, the protection equipment is controlled to make protection action by combining action delay;
According to the change condition of the phase jump quantity of the circuit where the protection equipment receives the active detection signal, the protection equipment is controlled to make protection action by combining action delay, and the protection equipment comprises:
The protection equipment makes protection actions according to the action delay sequence, and when each protection action response is finished, the change condition of phase jump variables of the alternating current voltage of the line where the protection equipment which does not make the protection actions is located is detected respectively;
and if the phase jump variable is reduced to the preset amount, stopping the protection action of the protection equipment, otherwise, continuously controlling the protection equipment to make the protection action according to the action delay sequence.
2. The method for protecting an active detection type power distribution network based on action delay according to claim 1, wherein the preset limit value is 70% of rated voltage of an ac system of the power distribution network.
3. The method for protecting an active detection type power distribution network based on action delay according to claim 1, wherein the step of obtaining a positive sequence fault component of the power distribution network and judging whether a protection starting condition is satisfied according to the positive sequence fault component comprises the steps of:
and acquiring a voltage component and a current component in the positive sequence fault component, calculating a phase difference between the voltage component and the current component, and judging that the protection starting condition is met when the phase difference is between-180 DEG and 180 deg.
4. The method for protecting an active detection type power distribution network based on action delay according to claim 1, wherein if the protection start condition is met, sending an active detection signal to a protection device in the power distribution network through a controllable power electronic device comprises:
When the protection starting condition is met, superposing a phase jump trigger signal on an original control signal of the input end of the controllable power electronic equipment;
The switching-off of a switching element in the controllable power electronic equipment is controlled through a phase jump trigger signal, so that the phase jump of an output signal of the controllable converter occurs;
And sending the output signal with the phase jump to protection equipment in the power distribution network as an active detection signal.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111489437.2A CN114374193B (en) | 2021-12-08 | Active detection type power distribution network protection method based on action delay |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111489437.2A CN114374193B (en) | 2021-12-08 | Active detection type power distribution network protection method based on action delay |
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| CN114374193A CN114374193A (en) | 2022-04-19 |
| CN114374193B true CN114374193B (en) | 2024-07-16 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108493907A (en) * | 2018-02-12 | 2018-09-04 | 国网山东省电力公司莱芜供电公司 | A kind of Amplitude Comparison guard method of adaptation active power distribution network |
| CN112952775A (en) * | 2021-02-26 | 2021-06-11 | 国网河南省电力公司电力科学研究院 | Method for protecting voltage quantity of power distribution network containing distributed photovoltaic power supply |
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108493907A (en) * | 2018-02-12 | 2018-09-04 | 国网山东省电力公司莱芜供电公司 | A kind of Amplitude Comparison guard method of adaptation active power distribution network |
| CN112952775A (en) * | 2021-02-26 | 2021-06-11 | 国网河南省电力公司电力科学研究院 | Method for protecting voltage quantity of power distribution network containing distributed photovoltaic power supply |
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