阅读说明：本技术 投切线路的实时短路电流计算方法及装置 (Real-time short-circuit current calculation method and device for switching line ) 是由 周丹 周原 杨贤 蔡玲珑 李兴旺 刘建明 于 2021-09-10 设计创作，主要内容包括：本申请公开了投切线路的实时短路电流计算方法及装置,其中,投切线路的实时短路电流计算方法包括：实时监测线路投入前或者切除前的母线电压；获得线路长度、波阻抗和相位系数,并根据线路长度、波阻抗和相位系数计算线路入口阻抗；根据母线电压以及线路入口阻抗计算得出母线的短路阻抗；根据短路阻抗以及母线电压,计算出实时短路电流。通过上述方式,本申请公开通过观测投空线前后电压幅值变化获取短路容量的监测方法,能够结合实际电网测试结果对投切线路引起的母线电压进行观测得出短路电流水平,更能反映实际运行情况。(The application discloses a method and a device for calculating the real-time short-circuit current of a switching line, wherein the method for calculating the real-time short-circuit current of the switching line comprises the following steps: monitoring the bus voltage before the circuit is put into or cut off in real time; obtaining the line length, the wave impedance and the phase coefficient, and calculating the line inlet impedance according to the line length, the wave impedance and the phase coefficient; calculating the short circuit impedance of the bus according to the bus voltage and the line inlet impedance; and calculating real-time short-circuit current according to the short-circuit impedance and the bus voltage. Through the mode, the monitoring method for acquiring the short-circuit capacity by observing the voltage amplitude change before and after the throwing line can be combined with the actual power grid test result to observe the bus voltage caused by the throwing line to obtain the short-circuit current level, and the actual operation condition can be reflected better.)

1. A real-time short-circuit current calculation method for switching lines is characterized by comprising the following steps:

monitoring the bus voltage before the circuit is put into or cut off in real time;

obtaining the line length, the wave impedance and the phase coefficient, and calculating the line inlet impedance according to the line length, the wave impedance and the phase coefficient;

calculating the short circuit impedance of the bus according to the bus voltage and the line inlet impedance;

and calculating real-time short-circuit current according to the short-circuit impedance and the bus voltage.

2. The method for calculating the short-circuit current of the switching line according to claim 1, wherein the real-time monitoring of the bus voltage before the switching line is switched on or switched off comprises:

switching on/off operation is carried out on a line on a bus needing short-circuit capacity testing, and bus voltage steady-state values before and after switching on/off of the line are tested

3. The method for calculating the short-circuit current of the switching line according to claim 2, wherein the calculating the line inlet impedance according to the line length, the wave impedance and the phase coefficient comprises:

the line inlet impedance Z_REComprises the following steps: z_RK＝z/tan(l×a)；

Wherein l is the line length, z is the wave impedance, and the phase coefficient is a.

4. The method for calculating the short-circuit current of the switching line according to claim 3, wherein the calculating the short-circuit impedance of the bus according to the bus voltage and the line inlet impedance comprises:

when the system performs no-load line switching-on/switching-off operation, the voltage before and after switching-on can be represented by a first formula, wherein the first formula is as follows:

wherein Z is_RKThe head end inlet impedance when the tail end of the line is open; x_SShort circuit impedance of the bus;

calculating the short-circuit impedance X of the bus according to the first formula_S(ii) a j is the imaginary part of the complex number.

5. The method for calculating the real-time short-circuit current of the switching line according to claim 4, wherein the calculating the real-time short-circuit current according to the short-circuit impedance and the bus voltage comprises:

dividing the bus voltage by the short circuit impedance of the bus and dividing byThereby obtaining the short circuit current value in the actual network state.

6. A real-time short-circuit current calculation device for switching lines is characterized by comprising:

the bus voltage module is used for monitoring the bus voltage before the circuit is put into use or cut off in real time;

the line entrance impedance module is used for obtaining the line length, the wave impedance and the phase coefficient and calculating the line entrance impedance according to the line length, the wave impedance and the phase coefficient;

the short-circuit impedance module is used for calculating the short-circuit impedance of the bus according to the bus voltage and the line inlet impedance;

and the short-circuit current module is used for calculating the real-time short-circuit current according to the short-circuit impedance and the bus voltage.

7. The real-time short-circuit current calculation device for switching lines according to claim 6,

the bus voltage module is also used for carrying out switching-on/switching-off operation on the line on the bus needing to test the short-circuit capacity and testing the bus voltage steady-state values before and after the switching-on/switching-off of the line

8. The real-time short-circuit current calculation device for switching lines according to claim 7,

in the inlet impedance module, the line inlet impedance Z_REComprises the following steps: z_RK＝z/tan(l×a)；

Wherein l is the line length, z is the wave impedance, and the phase coefficient is a.

9. The device for calculating the real-time short-circuit current of the switching line according to claim 8, wherein in the short-circuit impedance module, when the system performs the no-load line switching on/off operation, the voltage before and after switching on can be represented by a first formula, wherein the first formula is as follows:

wherein Z is_RKThe head end inlet impedance when the tail end of the line is open; x_SShort circuit impedance of the bus;

calculating the short-circuit impedance X of the bus according to the first formula_S。

10. The device for calculating the real-time short-circuit current of the switching line according to claim 9,

the short-circuit current module is also used for dividing the voltage of the bus by the short-circuit impedance of the bus and dividing the voltage by the short-circuit impedance of the busThereby obtaining the short circuit current value in the actual network state.

Technical Field

The application relates to the technical field, in particular to a real-time short-circuit current calculation method and device for switching lines.

Background

The short-circuit current is an important parameter related to the stable operation of an electric power system and electric power equipment, the level of the short-circuit current may change along with the continuous expansion of the scale of the electric power system, the operation reliability of the equipment needs to be evaluated, the short-circuit current is calculated in an off-line mode in the prior art, errors caused by an equivalent strategy exist in calculation, the workload of manual calculation is huge, the updating period is long every year, and the actual operation condition of the system is difficult to reflect. The method is used for reflecting the equivalent impedance of the system through the voltage rise caused by the closing no-load circuit, so that the short-circuit current parameter of the system is obtained, the monitoring method is simple, the timeliness and the accuracy of calculation are greatly improved, and the calculation cost is reduced.

The existing calculation is carried out in an off-line network model construction mode, the calculation strategy has errors, the updating period is long, the calculation amount is large, and the actual real-time short-circuit current level of a power grid cannot be reflected.

Disclosure of Invention

The application provides a real-time short-circuit current calculation method and device for switching lines, and aims to solve the problem that the actual real-time short-circuit current level of a power grid cannot be reflected in the prior art.

In order to solve the technical problem, the application provides a method for calculating a real-time short-circuit current of a switching line, which comprises the following steps: monitoring the bus voltage before the circuit is put into or cut off in real time; obtaining the line length, the wave impedance and the phase coefficient, and calculating the line inlet impedance according to the line length, the wave impedance and the phase coefficient; calculating the short circuit impedance of the bus according to the bus voltage and the line inlet impedance; and calculating real-time short-circuit current according to the short-circuit impedance and the bus voltage.

Optionally, the monitoring, in real time, the bus voltage before the line is put into or cut off includes: switching on/off operation is carried out on the line on the bus needing to test the short-circuit capacity, and the stable state value of the bus voltage before and after switching on/off of the line is tested

Optionally, calculating the line inlet impedance from the line length, the wave impedance and the phase coefficient comprises: line inlet impedance Z_REComprises the following steps: z_RK＝z/tan(l×a)；

Where l is the line length, z is the wave impedance, and the phase coefficient is a.

Optionally, calculating the short-circuit impedance of the bus according to the bus voltage and the line inlet impedance includes: when the system performs no-load line switching-on/switching-off operation, the voltage before and after switching-on can be represented by a first formula, wherein the first formula is as follows:

wherein Z is_RKThe head end inlet impedance when the tail end of the line is open; x_SShort circuit impedance of the bus; calculating the short circuit impedance X of the bus according to a first formula_S(ii) a j is the imaginary part of the complex number.

Optionally, calculating a real-time short-circuit current according to the short-circuit impedance and the bus voltage, including: by dividing the bus voltage by the short-circuit impedance of the bus and dividing byThereby obtaining the short circuit current value in the actual network state.

In order to solve the above technical problem, the present application provides a real-time short-circuit current calculating device for switching lines, including: the bus voltage module is used for monitoring the bus voltage before the circuit is put into use or cut off in real time; the line entrance impedance module is used for obtaining the line length, the wave impedance and the phase coefficient and calculating the line entrance impedance according to the line length, the wave impedance and the phase coefficient; the short-circuit impedance module is used for calculating the short-circuit impedance of the bus according to the bus voltage and the line inlet impedance; and the short-circuit current module is used for calculating the real-time short-circuit current according to the short-circuit impedance and the bus voltage.

Optionally, the bus voltage module is further configured to perform switching on/off operation on a line on the bus requiring short-circuit capacity test, and test a steady-state value of the bus voltage before and after switching on/off of the line

Optionally, in the ingress impedance module, the line ingress impedance Z_REComprises the following steps: z_RK＝z/tan(l×a)

Where l is the line length, z is the wave impedance, and the phase coefficient is a.

Optionally, in the short-circuit impedance module, when the system performs an idle line closing/opening operation, the voltage before and after closing of the system may be represented by a first formula, where the first formula is:

wherein Z is_RKThe head end inlet impedance when the tail end of the line is open; x_SShort circuit impedance of the bus; calculating the short circuit impedance X of the bus according to a first formula_S。

Optionally, the short-circuit current module is further configured to divide the bus voltage by the short-circuit impedance of the bus and divide byThereby obtaining the short circuit current value in the actual network state.

The method and the device for calculating the short-circuit current of the switching line are provided, the bus voltage before the switching line is switched on or before the switching line is cut off is monitored in real time, the line inlet impedance is obtained by obtaining the line length, the wave impedance and the phase coefficient, and the short-circuit impedance of the bus is obtained through the bus voltage and the line inlet impedance, so that the real-time short-circuit current is calculated. Through the mode, the monitoring method for acquiring the short-circuit capacity by observing the voltage amplitude change before and after the throwing line can be combined with the actual power grid test result to observe the bus voltage caused by the throwing line to obtain the short-circuit current level, and the actual operation condition can be reflected better.

Drawings

In order to more clearly illustrate the technical solution of the present application, the drawings needed to be used in 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 application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic flow chart of an embodiment of a method for calculating a real-time short-circuit current of a switching line according to the present application;

fig. 2 is a schematic structural diagram of an embodiment of a real-time short-circuit current calculation device for switching lines according to the present application.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present application, the following describes in detail the method and apparatus for calculating the real-time short-circuit current of the switching line provided by the present application with reference to the accompanying drawings and the detailed description.

Referring to fig. 1, fig. 1 is a schematic flow chart of an embodiment of a method for calculating a real-time short-circuit current of a switching line according to the present application, in this embodiment, the method for calculating a real-time short-circuit current of a switching line may include steps S110 to S140, and each step is as follows:

s110: and monitoring the bus voltage before the line is put into use or cut off in real time.

Switching on/off operation is carried out on the line on the bus needing to test the short-circuit capacity, and the stable state value of the bus voltage before and after switching on/off of the line is tested

S120: the line length, wave impedance and phase coefficient are obtained, and the line entrance impedance is calculated from the line length, wave impedance and phase coefficient.

Line inlet impedance Z_REComprises the following steps: z_RK＝z/tan(l×a)

Where l is the line length, z is the wave impedance, and the phase coefficient is a. And l is the line length, z is the wave impedance, and the phase coefficient a is a known parameter obtained by field measurement.

S130: and calculating the short-circuit impedance of the bus according to the bus voltage and the line inlet impedance.

When the system performs the closing/opening operation of the no-load line, the voltage before and after closing can be represented by a first formula:

wherein Z is_RKThe head end inlet impedance when the tail end of the line is open; x_SShort circuit impedance of the bus; calculating the short circuit impedance X of the bus according to a first formula_S(ii) a j is the imaginary part of the complex number.

S140: and calculating real-time short-circuit current according to the short-circuit impedance and the bus voltage.

By dividing the bus voltage by the short-circuit impedance of the bus and dividing byThereby obtaining the short circuit current value in the actual network state.

The inlet impedance of the line is constant after the line is built, so repeated measurement is not needed, and the actual system short-circuit current can be obtained only by monitoring the bus voltage change condition. In addition, the embodiment combines the actual power grid test result to observe the bus voltage caused by the switching circuit to obtain the short-circuit current level, and can better reflect the actual operation condition.

Based on the switching line real-time short-circuit current calculation method, the present application also provides a switching line real-time short-circuit current calculation device, please refer to fig. 2, and fig. 2 is a schematic structural diagram of an embodiment of the switching line real-time short-circuit current calculation device of the present application. In this embodiment, the real-time short-circuit current calculating device for the switching line may include:

the bus voltage module 110 is used for monitoring the bus voltage before the circuit is put into use or cut off in real time;

a line entrance impedance module 120, configured to obtain a line length, a wave impedance, and a phase coefficient, and calculate a line entrance impedance according to the line length, the wave impedance, and the phase coefficient;

a short-circuit impedance module 130, configured to calculate a short-circuit impedance of the bus according to the bus voltage and the line inlet impedance;

and a short-circuit current module 140, configured to calculate a real-time short-circuit current according to the short-circuit impedance and the bus voltage.

Optionally, the bus voltage module is further configured to perform switching on/off operation on a line on the bus requiring short-circuit capacity test, and test a steady-state value of the bus voltage before and after switching on/off of the line

Optionally, in the ingress impedance module, the line ingress impedance Z_REComprises the following steps: z_RK＝z/tan(l×a)

Where l is the line length, z is the wave impedance, and the phase coefficient is a.

Optionally, in the short-circuit impedance module, when the system performs an idle line closing/opening operation, the voltage before and after closing of the system may be represented by a first formula:

wherein Z is_RKThe head end inlet impedance when the tail end of the line is open; x_SShort circuit impedance of the bus; calculating the short circuit impedance X of the bus according to a first formula_S。

Optionally, the short-circuit current module is further used for utilizing the short-circuit impedance phase of the bus voltage and the busIs divided byThereby obtaining the short circuit current value in the actual network state.

The method and the device for calculating the short-circuit current of the switching line are provided, the bus voltage before the switching line is switched on or before the switching line is cut off is monitored in real time, the line inlet impedance is obtained by obtaining the line length, the wave impedance and the phase coefficient, and the short-circuit impedance of the bus is obtained through the bus voltage and the line inlet impedance, so that the real-time short-circuit current is calculated. Through the mode, the monitoring method for acquiring the short-circuit capacity by observing the voltage amplitude change before and after the throwing line can be combined with the actual power grid test result to observe the bus voltage caused by the throwing line to obtain the short-circuit current level, and the actual operation condition can be reflected better.

It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not limiting of the application. In addition, for convenience of description, only a part of structures related to the present application, not all of the structures, are shown in the drawings. The step numbers used herein are also for convenience of description only and are not intended as limitations on the order in which the steps are performed. 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 application.

The terms "first", "second", etc. in this application are used to distinguish between different objects and not to describe a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.