阅读说明：本技术 高压断路器短路开断能力评估及选相开断控制方法 (Short-circuit breaking capacity evaluation and phase selection breaking control method for high-voltage circuit breaker ) 是由 杨为 朱太云 田宇 柯艳国 朱胜龙 张国宝 赵恒阳 蔡梦怡 陈忠 李坚林 罗沙 于 2020-04-23 设计创作，主要内容包括：本发明实施方式提供一种高压断路器短路开断能力评估及选相开断控制方法,属于电网短路开断与智能测控技术领域。所述控制方法包括：将大电网网架分割为计算区域和外部区域；扫描形成计算区域内的各个节点的正序网络、负序网络以及零序网络；采用电磁暂态计算的方法获取每个节点的短路电流和直流时间常数；判断短路电流是否大于或等于节点对应的额定短路电流；在判断短路电流小于短路电流的情况下,判断直流时间常数是否小于或等于额定直流时间常数；在判断直流时间常数大于额定直流时间常数的情况下,对断路器的开断能力进行校核；判断开断能力是否大于短路电流；在判断开断能力小于或等于短路电流的情况下,采用选项开断控制方法控制断路器。(The embodiment of the invention provides a method for evaluating the short-circuit breaking capacity and controlling phase-selection breaking of a high-voltage circuit breaker, and belongs to the technical field of power grid short-circuit breaking and intelligent measurement and control. The control method comprises the following steps: dividing a large power grid network frame into a calculation area and an external area; scanning to form a positive sequence network, a negative sequence network and a zero sequence network of each node in a calculation region; acquiring the short-circuit current and the direct-current time constant of each node by adopting an electromagnetic transient calculation method; judging whether the short-circuit current is larger than or equal to the rated short-circuit current corresponding to the node; under the condition that the short-circuit current is judged to be smaller than the short-circuit current, judging whether the direct current time constant is smaller than or equal to a rated direct current time constant or not; checking the breaking capacity of the circuit breaker under the condition that the direct current time constant is judged to be larger than the rated direct current time constant; judging whether the on-off capacity is larger than the short-circuit current or not; and under the condition that the on-off capacity is judged to be less than or equal to the short-circuit current, controlling the circuit breaker by adopting an option on-off control method.)

1. A method for evaluating the short-circuit breaking capacity and controlling phase selection breaking of a high-voltage circuit breaker is characterized by comprising the following steps:

dividing a large power grid network frame into a calculation area and an external area based on real-time information data of the power flow of the large power grid network frame;

scanning and forming a positive sequence network, a negative sequence network and a zero sequence network of each node in the calculation region;

acquiring the short-circuit current and the direct-current time constant of each node by adopting an electromagnetic transient calculation method;

judging whether the short-circuit current is larger than or equal to the rated short-circuit current corresponding to the node;

sending an alarm to a system under the condition that the short-circuit current is judged to be greater than or equal to the rated short-circuit current;

under the condition that the short-circuit current is judged to be smaller than the short-circuit current, whether the direct-current time constant is smaller than or equal to a rated direct-current time constant corresponding to the node or not is judged;

under the condition that the direct current time constant is judged to be larger than the rated direct current time constant, checking the breaking capacity of the circuit breaker by adopting a method for checking the breaking capacity of the last half-wave energy equivalent principle of the short-circuit current;

judging whether the breaking capacity is larger than the short-circuit current or not;

and under the condition that the on-off capacity is judged to be less than or equal to the short-circuit current, a preset phase selection on-off control method is adopted to control the circuit breaker, so that the standard exceeding of the direct-current component of the short-circuit current under the condition of first opening of a large half-wave is avoided when the circuit breaker is in an on-off short-circuit fault.

2. The control method according to claim 1, characterized in that the control method further comprises:

and under the condition that the direct current time constant is judged to be less than or equal to the rated direct current time constant, determining that the circuit breaker is in a normal state.

3. The control method according to claim 1, characterized in that the control method further comprises:

and determining that the circuit breaker is in a normal working state under the condition that the breaking capacity is judged to be larger than the short-circuit current.

4. The control method of claim 1, wherein the checking the breaking capacity of the circuit breaker by using the breaking capacity checking method based on the energy equivalence principle of the last half wave of the short-circuit current further comprises:

calculating the occlusion coefficient according to the formula (1),

wherein K is the shielding coefficient, t_1N、t_2NRespectively the starting time, the ending time, t of the second large half-wave when the first large half-wave is at the maximum asymmetry under the rated direct current time constant₁、t₂Respectively the starting time and the ending time of the second large half-wave when the first large half-wave is at the maximum asymmetry degree under the direct current time constant_dNIs said nominal time constant, T_dcIs the dc time constant.

5. The control method according to claim 1, wherein determining whether the short-circuit current is greater than or equal to a rated short-circuit current corresponding to the node specifically comprises:

and inquiring the rated short-circuit current through the electric power Internet of things information public platform.

6. The control method according to claim 1, wherein determining whether the dc time constant is less than or equal to a rated dc time constant corresponding to the node specifically comprises:

and inquiring the rated direct current time constant through the electric power Internet of things information public platform.

7. A high voltage circuit breaker short circuit breaking capability evaluation and phase selection breaking control system, characterized in that the control system comprises a processor configured to execute the control method according to any one of claims 1 to 6.

8. A storage medium storing instructions for reading by a machine to cause the machine to perform a control method according to any one of claims 1 to 6.

Technical Field

The invention relates to the technical field of power grid short circuit breaking and intelligent measurement and control, in particular to a high-voltage circuit breaker short circuit breaking capacity evaluation and phase selection breaking control method.

Background

With the continuous increase of the capacity of a generator and the capacity of a transformer in a power system in China and the continuous improvement of the voltage grade of a transmission line, the short-circuit current of the system is larger than or close to the rated breaking capacity of a high-voltage alternating-current circuit breaker. At present, current limiting measures such as a high-impedance transformer and a series impedance are adopted for solving the problem of short-circuit current, and the short-circuit current is limited within the range of rated breaking capacity, but the ratio of reactance at a short-circuit node to resistance is increased, and a direct-current time constant exceeds a rated time constant of a circuit breaker, so that the actual breaking capacity of the circuit breaker is greatly influenced.

Therefore, it will happen that the short-circuit current approaches the rated breaking capacity of the high-voltage ac circuit breaker and the actual time constant is greater than the rated dc time constant, which will seriously affect the breaking capacity of the asymmetric short-circuit current of the high-voltage ac circuit breaker, the dc component of the expected zero crossing of the short-circuit current will exceed the value in the circuit breaker type test report, the asymmetric breaking capacity of the circuit breaker will not be guaranteed, which generally means that the breaking capacity of the circuit breaker will be reduced.

Disclosure of Invention

The invention aims to provide a method for evaluating the short-circuit breaking capacity and controlling the phase selection breaking of a high-voltage circuit breaker, which can control and correct the working condition of reduced breaking capacity of the circuit breaker in time so as to ensure the stable operation of a power system.

In order to achieve the above object, an embodiment of the present invention provides a method for evaluating short circuit breaking capability and controlling phase selection breaking of a high voltage circuit breaker, where the method includes:

dividing a large power grid network frame into a calculation area and an external area based on real-time information data of the power flow of the large power grid network frame;

scanning and forming a positive sequence network, a negative sequence network and a zero sequence network of each node in the calculation region;

acquiring the short-circuit current and the direct-current time constant of each node by adopting an electromagnetic transient calculation method;

judging whether the short-circuit current is larger than or equal to the rated short-circuit current corresponding to the node;

sending an alarm to a system under the condition that the short-circuit current is judged to be greater than or equal to the rated short-circuit current;

under the condition that the short-circuit current is judged to be smaller than the short-circuit current, whether the direct-current time constant is smaller than or equal to a rated direct-current time constant corresponding to the node or not is judged;

under the condition that the direct current time constant is judged to be larger than the rated direct current time constant, checking the breaking capacity of the circuit breaker by adopting a method for checking the breaking capacity of the last half-wave energy equivalent principle of the short-circuit current;

judging whether the breaking capacity is larger than the short-circuit current or not;

and under the condition that the on-off capacity is judged to be less than or equal to the short-circuit current, a preset phase selection on-off control method is adopted to control the circuit breaker, so that the standard exceeding of the direct-current component of the short-circuit current under the condition of first opening of a large half-wave is avoided when the circuit breaker is in an on-off short-circuit fault.

Optionally, the control method further comprises:

and under the condition that the direct current time constant is judged to be less than or equal to the rated direct current time constant, determining that the circuit breaker is in a normal state.

Optionally, the control method further comprises:

and determining that the circuit breaker is in a normal working state under the condition that the breaking capacity is judged to be larger than the short-circuit current.

Optionally, the checking the breaking capacity of the circuit breaker by using the breaking capacity checking method based on the short-circuit current last half-wave energy equivalence principle further includes:

calculating the occlusion coefficient according to the formula (1),

wherein K is the shielding coefficient, t_1N、t_2NRespectively the starting time, the ending time, t of the second large half-wave when the first large half-wave is at the maximum asymmetry under the rated direct current time constant₁、t₂Respectively the starting time and the ending time of the second large half-wave when the first large half-wave is at the maximum asymmetry degree under the direct current time constant_dNIs said nominal time constant, T_dcIs the dc time constant.

Optionally, the determining whether the short-circuit current is greater than or equal to the rated short-circuit current corresponding to the node specifically includes:

and inquiring the rated short-circuit current through the electric power Internet of things information public platform.

Optionally, the determining whether the dc time constant is less than or equal to the rated dc time constant corresponding to the node specifically includes:

and inquiring the rated direct current time constant through the electric power Internet of things information public platform.

In another aspect, the present invention further provides a short circuit breaking capability evaluation and phase selection breaking control system for a high voltage circuit breaker, where the control system includes a processor configured to execute any one of the control methods described above.

In yet another aspect, the present invention also provides a storage medium storing instructions for reading by a machine to cause the machine to perform the control method as described in any one of the above.

According to the technical scheme, the method for evaluating the short-circuit breaking capacity and controlling the phase selection breaking of the high-voltage circuit breaker divides the large power grid network frame into the calculation area and the external area on the basis of the real-time information data of the power flow of the large power grid network frame, and then respectively judges the relation between the actual short-circuit current and the rated short-circuit current, and the relation between the actual direct-current time constant and the rated direct-current time constant, so that the working state of the current circuit breaker is accurately obtained, corresponding control measures are made on the basis of the working state, and the stable operation of a power system is guaranteed.

Additional features and advantages of embodiments of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention without limiting the embodiments of the invention. In the drawings:

fig. 1 is a flow chart of a high voltage circuit breaker short circuit breaking capability evaluation and phase selection breaking control method according to an embodiment of the invention;

FIG. 2 is a waveform diagram of a first large half-wave before modulation using a predetermined phase selection on-off control method according to an embodiment of the present invention; and

fig. 3 is a waveform diagram of the first large half wave modulated by the preset phase selection on-off control method according to an embodiment of the invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration and explanation only, not limitation.

In the embodiments of the present invention, unless otherwise specified, the use of directional terms such as "upper, lower, top, and bottom" is generally used with respect to the orientation shown in the drawings or the positional relationship of the components with respect to each other in the vertical, or gravitational direction.

In addition, if there is a description of "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between the various embodiments can be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not be within the protection scope of the present invention.

Fig. 1 is a flow chart of a short-circuit breaking capability evaluation and phase selection breaking control method of a high-voltage circuit breaker according to an embodiment of the invention. In fig. 1, the control method may include:

in step S10, the large grid rack is divided into a calculation region and an external region based on the real-time information data of the large grid rack flow. The calculation region may be a region where a node corresponding to a circuit breaker for evaluation and control is located; the outer zone may then be a zone where no evaluation and control operations are currently required to be performed. Further, for this calculation region, a detailed circuit model can be built from the grid structure and load data. And for the outer region, an equivalent circuit may be used for representation.

In step S11, the scan forms a positive sequence network, a negative sequence network, and a zero sequence network for each node within the calculation region. Wherein the positive sequence network may be a computational network determined by the power system positive sequence network topology and the positive sequence parameters of the elements; the negative sequence network may be a computational network determined by the negative sequence network topology of the power system and the negative sequence parameters of the elements; the zero sequence network may be a computational network determined by the zero sequence network topology of the power system and the zero sequence parameters of the elements.

In step S12, the short-circuit current and the dc time constant of each node are obtained by using an electromagnetic transient calculation method. In this embodiment, the specific manner of the electromagnetic transient calculation method may be various manners known to those skilled in the art, and should be known to those skilled in the art, and therefore, will not be described herein again.

In step S13, it is determined whether the short-circuit current is greater than or equal to the rated short-circuit current corresponding to the node. The rated short-circuit current can be queried through an electric power internet of things information public platform, for example. The electric power internet of things information public platform stores a nameplate value of each breaker and is preset with an external network protocol, so that an electric power system can be directly connected through a network end to obtain the rated short-circuit current.

In step S14, when the short-circuit current is determined to be equal to or greater than the rated short-circuit current, an alarm is issued to the system. In this embodiment, when the short-circuit current is greater than or equal to the rated short-circuit current, the high-voltage circuit breaker cannot break the short-circuit fault current at the node of the power system, indicating that there is a fault at the node of the power system at that time. Thus, an alarm may be issued to the system. After the system receives the alarm, measures such as changing the operation mode (for example, reducing the current power transmission power) can be taken to deal with the alarm.

In step S15, when it is determined that the short-circuit current is smaller than the short-circuit current, it is determined whether or not the dc time constant is smaller than or equal to a rated dc time constant corresponding to the node. The rated direct current time constant can be queried through an electric power internet of things information public platform, for example.

In step S16, in the case where the dc time constant is judged to be less than or equal to the rated dc time constant, it is determined that the circuit breaker is in a normal state. In this embodiment, a dc time constant less than or equal to the nominal dc time constant for the node indicates that the circuit breaker is still able to break the short circuit fault current and the asymmetric short circuit fault current at the node of the power system at that time. Therefore, the circuit breaker is in a normal working state at this time, and may not be processed.

In step S17, when the dc time constant is determined to be greater than the rated dc time constant, the breaking capacity of the circuit breaker is checked by using the breaking capacity checking method based on the last half-wave energy equivalence principle of the short-circuit current. In particular, in this embodiment, the breaking capacity may be equal to the product of its rated short-circuit current and the breaking coefficient. Further, the occlusion coefficient may be calculated using equation (1),

wherein K is the coefficient of interruption, t_1N、t_2NRespectively the starting time, the ending time, t of the second large half-wave when the first large half-wave is at the maximum asymmetry under the rated direct current time constant₁、t₂Respectively the starting time and the ending time of the second large half-wave when the first large half-wave is at the maximum asymmetry degree under the direct current time constant_dNIs a rated time constant, T_dcIs a dc time constant.

In step S18, it is determined whether or not the breaking capability is larger than the short-circuit current.

In step S19, when the breaking capability is determined to be greater than the short-circuit current, it is determined that the circuit breaker is in a normal operating state.

In step S20, when the open-close capability is determined to be less than or equal to the short-circuit current, the circuit breaker is controlled by a preset phase-selection open-close control method, so that the standard exceeding of the short-circuit current dc component under the condition of the first large half-wave is avoided when the circuit breaker is open-close short-circuit fault. In this embodiment, as a specific mode of the phase-selection on-off control method, for example, a waveform of a short-circuit fault current is obtained through a power grid smart measurement and control layer, and an expected short-circuit fault current waveform and a dc component of each phase are derived, where an operation time of the process is less than or equal to 5 m. As shown in fig. 2, the a-phase dc component is maximum and 67.6%, which is the first large half wave. And then, a switching-off command is sent to an intelligent control element pre-installed on the circuit breaker, so that the first-opened phase appears in the C phase with the smaller direct-current component, and the later-opened phase appears in the A phase with the largest direct-current component. As shown in fig. 2, the first-phase dc component is reduced to 37%, which is much lower than the original 67.6%, so that the purpose of phase selection on-off control can be achieved.

In one example of the present invention, when the rated short-circuit current is 63kA and the rated dc time constant is 45ms, the calculated actual short-circuit current is 55kA and the dc time constant is 65 ms. Then, the breaking coefficient K calculated according to the formula (1) is 0.9086, and the actual breaking capacity of the circuit breaker is 57.2kA, which is greater than the actual short-circuit current 50 kA. Thus, the circuit breaker can successfully break the short circuit current without any treatment.

In another example of the invention, the calculated actual short-circuit current is 45kA and the dc time constant is 95ms at a rated short-circuit current of 50kA and a rated dc time constant of 45 ms. Then, the breaking coefficient K calculated according to the formula (1) is 0.8419, and the actual breaking capacity of the circuit breaker is 42.1kA, which is smaller than the actual short-circuit current 45 kA. Therefore, the circuit breaker cannot successfully cut off the short-circuit current, and a phase selection cut-off control method needs to be executed.

In another aspect, the present invention further provides a short circuit breaking capability evaluation and phase selection breaking control method for a high-voltage circuit breaker, where the control system may include a processor, and the processor may be configured to execute any one of the control methods described above.

In yet another aspect, the present invention also provides a storage medium which may store instructions which can be used to be read by a machine to cause the machine to perform the control method as any one of the above.

According to the technical scheme, the method, the system and the storage medium for evaluating the short-circuit breaking capacity and controlling the phase selection breaking of the high-voltage circuit breaker divide a large power grid network frame into a calculation area and an external area on the basis of real-time information data of the power flow of the large power grid network frame, and then respectively judge the relation between the actual short-circuit current and the rated short-circuit current, and the relation between the actual short-circuit current and the rated direct-current time constant, so that the working state of the current circuit breaker is accurately obtained, corresponding control measures are taken on the basis of the working state, and the.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the embodiments of the present invention are not limited to the details of the above embodiments, and various simple modifications can be made to the technical solution of the embodiments of the present invention within the technical idea of the embodiments of the present invention, and the simple modifications all belong to the protection scope of the embodiments of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, the embodiments of the present invention will not be described separately for the various possible combinations.

Those skilled in the art can understand that all or part of the steps in the method for implementing the above embodiments may be implemented by a program to instruct related hardware, where the program is stored in a storage medium and includes several instructions to enable a (may be a single chip, a chip, etc.) or a processor (processor) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

In addition, various different embodiments of the present invention may be arbitrarily combined with each other, and the embodiments of the present invention should be considered as disclosed in the disclosure of the embodiments of the present invention as long as the embodiments do not depart from the spirit of the embodiments of the present invention.