On-line monitoring method for surface charge and surface discharge of direct-current GIL / GIS

Abstract

The invention relates to a direct current GIL / GIS surface charge and surface discharge on-line monitoring method, which is used for a direct current GIL / GIS, and comprises the following steps: S1, carrying out the corresponding division of the surface area of an insulator based on a number; s2, establishing a GIL / GIS model, and performing corresponding numbering and division; s3, the simulated induced voltage is calculated, and a contribution coefficient matrix is calculated based on the simulated induced voltage; s4, on the basis of the induction current, actual induction voltage is obtained through calculation in combination with the measurement resistance, and actual surface charge density is obtained through calculation; and S5, judging the position area of the creeping discharge point according to the amplitude of the pulse current on each segmented electrode. Compared with the prior art, the direct-current GIL / GIS basin-type insulator surface charge online measurement device has the advantages of realizing online measurement of the direct-current GIL / GIS basin-type insulator surface charge and the

Description

Technical Field

[0001] The invention relates to the technical field of electrical equipment status monitoring and fault diagnosis, and in particular to an online monitoring method for surface charge and surface discharge of a DC GIL / GIS. Background Art

[0002] Gas-insulated metal-enclosed switchgear and transmission line (GIS / GIL) have the advantages of strong anti-interference ability, compact structure, reliable operation, small footprint and long maintenance cycle, and are now widely used in various voltage levels between 66kV-550kV. Compared with conventional electrical equipment, it will not be greatly affected by changes in the external environment, has outstanding fire resistance, high safety performance, and maintenance work is nearly half less than other ordinary electrical appliances. With the vigorous development of high-voltage direct current transmission, the construction of direct current GIL / GIS has gradually received widespread attention and has been gradually applied to power grid systems, playing a vital role. However, for direct current GIL / GIS, due to the long-term exposure to unipolar voltage, the surface of the internal basin insulator is very easy to accumulate surface charge. The accumulation of surface charge will distort the electric field along the surface of the insulator, causing the surface flashover voltage to decrease, and may eventually induce surface discharge of the insulator, which greatly affects the safe and stable operation of the power grid system. Therefore, if the surface charge and surface discharge of DC GIL / GIS insulators can be monitored online before a fault occurs, the fault can be discovered and located in time, helping operation and maintenance personnel to eliminate the fault in time, thus avoiding major accidents.

[0003] The measurement technology of the surface charge of DC GIL / GIS pot-type insulators currently focuses on using electrostatic probes to scan and measure the surface area of ​​the insulator point by point. This method is limited by the probe measurement principle and requires the installation of a probe control system inside the GIL / GIS. It is also difficult to achieve online measurement of the charge density of the entire surface of the insulator under high voltage conditions. In addition, the probe inside the GIL / GIS is likely to affect the normal operation of the equipment. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide an online monitoring method for surface charge and surface discharge of DC GIL / GIS, which can simultaneously realize online monitoring and regional positioning of surface discharge of insulators, and solve the electrical safety problems of built-in discharge sensors and the inaccurate monitoring problems of external sensors in the prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A method for online monitoring of surface charge and surface discharge of a DC GIL / GIS is provided, which is used for the DC GIL / GIS. The DC GIL / GIS comprises an outer shell, and one end of the DC GIL / GIS is provided with a central conductor and an insulator, wherein the insulator is a pot-type insulator.

[0007] The annular segmented electrode is arranged at the junction of the insulator and the shell, is sleeved outside the shell, and is connected to one end of the measuring resistor through a shielded wire. The other end of the measuring resistor is connected to the current measuring device. The annular segmented electrode is composed of a plurality of segmented electrodes with equal arc length, equal intervals and centrally symmetrical arrangement.

[0008] The method comprises the following steps:

[0009] S1. Obtain the number of each segmented electrode, and divide the surface area of ​​the insulator accordingly based on the number;

[0010] S2. Establish a GIL / GIS model, and number and divide the segmented electrodes and insulators of the established model accordingly according to the segmented electrodes and insulators of S1;

[0011] S3, sequentially setting the unit surface charge density for the surface area of ​​the insulator of the model, simulating and calculating the simulated induced voltage of the annular segmented electrode after each setting of the unit surface charge density, and calculating the contribution coefficient matrix based on the simulated induced voltage;

[0012] S4. Based on the current measuring device, the actual induced current of the annular segmented electrode is obtained, and the actual induced voltage is calculated in combination with the measured resistance, and then the surface charge density of each divided area of ​​the insulator of the actual DC GIL / GIS is calculated in combination with the contribution coefficient matrix;

[0013] S5. When the current measuring device detects a pulse current waveform generated by surface discharge on the insulator surface on the annular segmented electrode, the location area of ​​the surface discharge point is determined according to the amplitude of the pulse current on each segmented electrode.

[0014] Furthermore, the simulated induced voltage is:

[0015]

[0016] Among them, V1 to V n are the simulated induced voltages corresponding to the segment electrodes from segment 1 to segment n, σ1 to σ n The surface areas of the insulators are divided from the first to the nth surface areas, H ij is the insulator surface σ i Region pair j segment electrode C j Upper induction voltage V j The contribution coefficient of .

[0017] Furthermore, the surface charge density of each divided area of ​​the insulator is:

[0018]

[0019] Among them, σ real1 to realn is the surface charge density corresponding to the divided area of ​​each insulator, H ij is the insulator surface σ i Region pair j segment electrode C j Upper induction voltage V j The contribution coefficient of arrive are the actual induced voltages corresponding to the segmented electrodes from the 1st segment to the nth segment, respectively. The actual induced voltages are calculated based on the resistance value of the measuring resistor and the measured actual induced current.

[0020] Furthermore, the location area of ​​the surface discharge point is: the surface sector area of ​​the insulator radiated by the segmented electrode with the largest pulse current amplitude.

[0021] Furthermore, each segmented electrode is isolated by a solid insulating material.

[0022] Furthermore, the annular segmented electrode is isolated from the shell by a solid insulating material.

[0023] Furthermore, the solid insulating material is epoxy resin.

[0024] Furthermore, a GIL / GIS model was established based on finite element software.

[0025] Furthermore, the established model is identical to the actual DC GIL / GIS configuration.

[0026] Furthermore, the housing is grounded.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention calculates the induced voltage corresponding to the annular segmented electrode outside the GIL / GIS, analyzes and obtains the surface charge density of each divided area of ​​the insulator, and realizes the online measurement of the surface charge of the DC GIL / GIS pot-type insulator, thereby avoiding the problem of using an electrostatic probe to scan the surface of the insulator one by one and the difficulty in realizing online measurement of the surface charge in the prior art. At the same time, it avoids the difficulty of placing the electrostatic probe inside the equipment in the prior art and the influence of the built-in partial discharge sensor on the normal operation of the equipment.

[0029] (2) When a pulse current waveform caused by surface discharge on the insulator is detected on the annular segmented electrode based on the current measurement device, the present invention determines the location area of ​​the surface discharge point according to the amplitude of the pulse current on each segmented electrode, thereby realizing online monitoring and regional positioning of the surface discharge of the insulator, solving the electrical safety problem of the built-in discharge sensor and the inaccurate monitoring problem of the external sensor in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a flow chart of the present invention;

[0031] Figure 2 It is a structural schematic diagram of the present invention;

[0032] Figure 3 This is the internal structure diagram of the DC GIL / GIS of the present invention;

[0033] Figure 4 A schematic diagram of the numbering of the annular segmented electrodes and the division of the surface areas of the insulators of the present invention;

[0034] In the figure, GIL / GIS 1, casing 2, insulator 3, center conductor 4, annular segmented electrode 5, shielding wire 6, measuring resistor 7, current measuring device 8, insulating material 9. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0036] The present invention proposes an online monitoring method for the surface charge and surface discharge of a DC GIL / GIS. The present invention adopts an online monitoring method for the surface charge and surface discharge of a DC GIL / GIS basin insulator based on an annular segmented electrode, which can not only realize real-time monitoring of the surface charge of a DC GIL / GIS basin insulator, but also monitor the surface discharge of the insulator. According to the monitoring results, a comprehensive and scientific judgment can be made on whether the monitored equipment can continue to operate safely and stably, its operating conditions and characteristic laws can be mastered, its existing faults and defects can be identified, and possible abnormal problems can be predicted and handled in time, so as to truly achieve the purpose of prevention first and truly meet the needs of smart grids. The present invention includes an annular segmented electrode design, induced current measurement, insulator surface charge distribution calculation and surface discharge area positioning. The annular segmented electrode design includes electrode shape design, segmentation design and installation design. The annular segmented electrode is connected to a measuring resistor through a shielded wire, and the other end of the measuring resistor is connected to an induced current measuring device. The insulator surface charge distribution calculation includes insulator surface area division, contribution coefficient calculation and surface charge density distribution inversion calculation. The discharge area positioning of the insulator surface is to collect the induced pulse voltage caused by the surface discharge by using the annular segmented electrode, and perform the discharge area positioning calculation according to the numerical value of the induced voltage of each segmented electrode.

[0037] The process of the method of the present invention is as follows Figure 1 The method is used for DC GIL / GIS1. The structure diagram of DC GIL / GIS is shown in Figure 2 The internal structure of DC GIL / GIS is shown in Figure 3 As shown. The DC GIL / GIS1 includes an external shell 2, and a central conductor 4 and an insulator 3 are provided at one end of the DC GIL / GIS1. The insulator 3 is a pot-type insulator. The annular segmented electrode 5 is provided at the junction of the insulator 3 and the shell 2, and is sleeved on the outside of the shell 2. It is connected to one end of the measuring resistor 7 through a shielding wire 6. The other end of the measuring resistor 7 is connected to a current measuring device 8. The annular segmented electrode 5 is composed of a plurality of segmented electrodes with equal arc length, equal intervals and centrally symmetrical arrangement. Each segmented electrode is isolated by a solid insulating material 9. The annular segmented electrode 5 is also isolated from the shell 2 by a solid insulating material 9. The insulating material 9 is epoxy resin. Based on the above structure, the method of the present invention includes the following steps:

[0038] S1. Obtain the serial number of each segmented electrode, and divide the surface area of ​​the insulator 3 accordingly based on the serial number;

[0039] S2, establish a model of GIL / GIS1, and number and divide the segmented electrodes and insulators of the established model accordingly according to the segmented electrodes and insulators 3 of S1;

[0040] S3, sequentially setting the unit surface charge density for the surface area of ​​the insulator 3 of the model, simulating and calculating the simulated induced voltage of the annular segmented electrode 5 after each setting of the unit surface charge density, and calculating the contribution coefficient matrix based on the simulated induced voltage;

[0041] S4, obtaining the actual induced current of the annular segmented electrode 5 based on the current measuring device 8, combining with the measuring resistor 7, calculating the actual induced voltage, and then calculating the actual surface charge density of each divided area of ​​the insulator 3 of the DC GIL / GIS1 in combination with the contribution coefficient matrix;

[0042] S5. When the current measuring device 8 detects a pulse current waveform generated by surface discharge on the insulator 3 on the annular segmented electrode 5, the location area of ​​the surface discharge point is determined according to the amplitude of the pulse current on each segmented electrode.

[0043] In S1, the annular segmented electrodes 5 are numbered in sequence, and the surface of the insulator is divided into regions according to the number of electrode segments. In some embodiments, the number of divisions may be 12. The schematic diagram of the division is shown in FIG. Figure 4 As shown, the annular segmented electrodes are numbered C1, C2, ... C 12 , the insulator surface is divided into areas numbered σ1, σ2, …σ 12 .

[0044] In S2, a model identical to the actual measurement equipment is established using finite element software, including the DC GIL / GIS cavity, insulator, center conductor, and annular segmented electrode, and the insulator surface is divided into the same area.

[0045] In S3, the simulated induced voltage is:

[0046]

[0047] Among them, V1 to V n are the simulated induced voltages corresponding to the segment electrodes from segment 1 to segment n, σ1 to σ n The first to nth surface areas of the insulator 3 are divided respectively, and H ij is the insulator surface σ i Region pair j segment electrode C j Upper induction voltage V j The contribution coefficient of .

[0048] If the number of divisions is 12, the finite element software is used to divide the insulator surface into regions σ1, σ2, …σ 12 Set the unit surface charge density to 1uC / m 2 , the simulation calculates the ring segmented electrodes C1, C2, ... C each time the unit surface charge density is set12 The induced voltages are recorded as V1, V2, ... V 12 , so each time we get:

[0049]

[0050] Among them, H ij is the insulator surface σ i Area to Ring Segmented Electrode C j Upper induction voltage V j After applying unit surface charge density simulation to all divided areas on the insulator surface, the contribution coefficient matrix H can be finally calculated.

[0051] In S4, the surface charge density of each divided area of ​​the insulator 3 is:

[0052]

[0053] Among them, σ real1 to realn is the surface charge density corresponding to the divided area of ​​each insulator 3, H ij is the insulator surface σ i Region pair j segment electrode C j Upper induction voltage V j The contribution coefficient of arrive are the actual induced voltages corresponding to the first to nth segment electrodes respectively, and the actual induced voltages are calculated based on the resistance value of the measuring resistor 7 and the measured actual induced current.

[0054] If the number of divisions is 12, then according to the actual measurement results of the induced current of the annular segmented electrode, the induced voltages of the annular segmented voltages calculated in combination with the measured resistance are Therefore, according to the contribution coefficient matrix H in S3, the surface charge density σ of each divided area of ​​the actual DC GIL / GIS pot insulator can be calculated real :

[0055]

[0056] In S5, the location area where the surface discharge point is located is the surface sector area of ​​the insulator 3 radiated by the segmented electrode with the largest pulse current amplitude.

[0057] The annular segmented electrode used in the present invention is installed on the outer shell of the GIL / GIS, which avoids the difficulty of placing the electrostatic probe inside the equipment in the prior art. At the same time, it avoids the influence of the built-in partial discharge sensor on the normal operation of the equipment, and solves the problem of poor monitoring effect of the external sensor. The present invention provides a method for calculating the surface charge distribution of the insulator based on the induced voltage of the annular segmented electrode. Compared with the prior art that requires scanning and measuring the surface of the insulator one by one through the electrostatic probe, the present invention can more conveniently realize the calculation of the surface charge distribution of the insulator. The present invention also provides a method for locating the surface discharge position of the insulator based on the induced voltage of the annular segmented electrode, which can monitor the surface discharge of the insulator in real time, and locate the surface discharge area of ​​the insulator according to the amplitude of the segmented electrode induced voltage.

[0058] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for online monitoring of surface charge and surface discharge of a DC GIL / GIS, characterized in that: Used for a DC GIL / GIS (1), the DC GIL / GIS (1) comprises an outer casing (2), one end of the DC GIL / GIS (1) is provided with a central conductor (4) and an insulator (3), the insulator (3) is a pot-type insulator, The annular segmented electrode (5) is arranged at the junction of the insulator (3) and the housing (2), is sleeved outside the housing (2), and is connected to one end of a measuring resistor (7) via a shielding wire (6), and the other end of the measuring resistor (7) is connected to a current measuring device (8), wherein the annular segmented electrode (5) is composed of a plurality of segmented electrodes of equal arc length, equal intervals, and arranged in a central symmetrical manner; The method comprises the following steps: S1, obtaining the serial number of each segmented electrode, and dividing the surface area of ​​the insulator (3) accordingly based on the serial number; S2, establishing a model of GIL / GIS (1), and numbering and dividing the segmented electrodes and insulators of the established model accordingly according to the segmented electrodes and insulators (3) of S1; S3, sequentially setting the unit surface charge density for the surface area of ​​the insulator (3) of the model, simulating and calculating the simulated induced voltage of the annular segmented electrode (5) after each setting of the unit surface charge density, and calculating the contribution coefficient matrix based on the simulated induced voltage; S4, obtaining the actual induced current of the annular segmented electrode (5) based on the current measuring device (8), combining with the measuring resistor (7), calculating the actual induced voltage, and then calculating the actual surface charge density of each divided area of ​​the insulator (3) of the DC GIL / GIS (1) in combination with the contribution coefficient matrix; S5. When the current measuring device (8) detects that a pulse current waveform is generated by the surface discharge on the insulator (3) and appears on the annular segmented electrode (5), the location area of ​​the surface discharge point is determined based on the amplitude of the pulse current on each segmented electrode.

2. The method for online monitoring of surface charge and surface discharge of a DC GIL / GIS according to claim 1, characterized in that: The simulated induced voltage is: Among them, V1 to V n are the simulated induced voltages corresponding to the segment electrodes from segment 1 to segment n, σ1 to σ n The first to nth surface areas of the divided insulator (3), H ij is the insulator surface σ i Region pair j segment electrode C j Upper induction voltage V j The contribution coefficient of .

3. The method for online monitoring of surface charge and surface discharge of a DC GIL / GIS according to claim 2, characterized in that: The surface charge density of each divided area of ​​the insulator (3) is: Among them, σ real1 to realn is the surface charge density corresponding to the divided area of ​​each insulator (3), H ij is the insulator surface σ i Region pair j segment electrode C j Upper induction voltage V j The contribution coefficient of arrive The actual induced voltages corresponding to the first to the nth segment electrodes are respectively obtained by calculation based on the resistance value of the measuring resistor (7) and the measured actual induced current.

4. The method for online monitoring of surface charge and surface discharge of a DC GIL / GIS according to claim 1, characterized in that: The location area of ​​the surface discharge point is: the surface sector area of ​​the insulator (3) radiated by the segmented electrode with the largest pulse current amplitude.

5. The method for online monitoring of surface charge and surface discharge of a DC GIL / GIS according to claim 1, characterized in that: Each segmented electrode is isolated by a solid insulating material (9).

6. The method for online monitoring of surface charge and surface discharge of a DC GIL / GIS according to claim 1, characterized in that: The annular segmented electrode (5) is isolated from the housing (2) by a solid insulating material (9).

7. A method for online monitoring of surface charge and surface discharge of a DC GIL / GIS according to claim 5 or 6, characterized in that: The solid insulating material (9) is epoxy resin.

8. The method for online monitoring of surface charge and surface discharge of a DC GIL / GIS according to claim 1, characterized in that: The GIL / GIS(1) model was established based on finite element software.

9. The method for online monitoring of surface charge and surface discharge of a DC GIL / GIS according to claim 8, characterized in that: The model established is identical to the actual DC GIL / GIS (1) structure.

10. The method for online monitoring of surface charge and surface discharge of a DC GIL / GIS according to claim 1, characterized in that: The housing (2) is grounded.

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