CN206832876U - A kind of DC earthing system power monitoring device - Google Patents

Abstract

The utility model discloses a kind of DC earthing system power monitoring device, it is related to power system measurement and on-line monitoring technique field.The DC earthing system power monitoring device, electric current in DC earthing system connectors is gathered by giant magnetoresistance sensor, and output difference signal is analyzed and processed for signal processing circuit, analysis result periodically or under abnormality is waken up into LoRa wireless communication modules and carries out remote data transmission, current information in DC earthing system connectors is sent to long-range transformer station, so that long-range transformer station monitors DC earthing system mode in real time；The DC earthing system power monitoring device internal structure is simple, and reliability is high, and measurement frequency, amplitude range are wide, batch making cost is cheap, long lifespan, and be hardly damaged under strong-electromagnetic field impact caused by high current effect, there is huge advantage in long-time monitors application scenario on-line.

Description

A current monitoring device for DC grounding system

technical field

The utility model belongs to the technical field of power system measurement and on-line monitoring, in particular to a current monitoring device for a DC grounding system.

Background technique

Commutation and grounding are the two most critical links in the DC transmission system, and they are also the link with the highest failure rate. The grounding system plays a vital role in the safe operation of the DC transmission system. There are usually two operating modes of the DC transmission system. One is bipolar operation. In this operating mode, the positive and negative bipolar lines form a complete circuit, and the current difference in the bipolar lines is an unbalanced current, which flows into the grounding system; the other is bipolar operation. The first is unipolar operation, including unipolar ground circuit operation and unipolar metal circuit operation. When unipolar metal circuit operation, one DC line acts as a pole line and another DC line forms a DC circuit. At this time, the current flowing into the grounding system Smaller, but in the operation of the single pole ground loop, the pole line and the ground form a loop, and a huge current of up to kA is injected into the ground at this time. According to the above operation mode, the grounding system mainly has two functions: 1) During bipolar operation, it clamps the neutral point potential of the converter station to prevent damage to the equipment of the converter station caused by the unbalanced voltage between the two poles and the ground; 2) The ground circuit of the single pole In operation, a DC link is provided. Regardless of the role, the ground electrode system plays a vital role in the DC transmission system.

Real-time online monitoring of the DC grounding system can effectively obtain key information of the DC grounding system, increase experience in DC operation, and prevent grounding system failures. The necessity of real-time on-line monitoring of DC system grounding electrodes is reflected in the following three aspects: 1) The current DC system has been put into operation for a short time, lacks operation and maintenance experience, and has no relevant standards and specifications for grounding electrode design and operation. Monitoring the system current can effectively accumulate relevant data and experience; 2) When the single pole ground loop is running, a huge current flows into the ground, which will cause serious step voltage problems and DC bias problems, the former will bring potential danger to people , the latter will cause the power equipment (transformer, generator, relay protection device and reactive power compensation device) near the ground electrode to vibrate and generate heat, reduce efficiency, and increase harmonics of the power grid under the influence of DC bias. Monitoring can quickly and accurately locate the cause of the fault and avoid potential risks; 3) Due to the effect of electrochemical corrosion, long-term current flowing into the ground will cause serious corrosion of the ground electrode and nearby pipelines. Long-term monitoring of the ground current can effectively evaluate the ground electrode and nearby pipelines. The degree of corrosion of the pipeline shall be timely taken protective measures (cathode protection and other measures).

Although the monitoring of the DC grounding system is very necessary, the current monitoring system still has many problems, which are mainly reflected in the following four aspects: 1) The mature and cheap current sensors on the market, such as CT coils and Rogowski coils, have a wide range of measurement frequencies. Including DC, and high-precision current sensors (such as photoelectric current transformers) whose measurement range includes DC are relatively expensive; 2) The current amplitude span to be measured is large, and the required current sensor needs to accurately measure unbalanced currents as small as 1A. The grounding current of a single pole earth loop up to several kA requires the current sensor to span at least 4 orders of magnitude; 3) The life of the current sensor is short, and the designed service life of the DC ground electrode is usually 30 years. The service life of the existing sensor It is rare for more than ten years, and the frequent maintenance of the ground electrode current monitoring system will bring a lot of additional operating costs; 4) Considering the huge ground current when the DC system single pole ground circuit is running, the ground electrode system is usually far away from the control center such as the substation (more than 10km), the current CAN bus monitoring system that has been put into use is complicated in wiring, and the long-distance wiring is expensive, with a high failure rate, using wireless communication, and ultra-long-distance wireless communication is a big problem.

Utility model content

Aiming at the deficiencies of the prior art, the utility model provides a current monitoring device for a DC grounding system.

The utility model solves the above-mentioned technical problems through the following technical solutions: a current monitoring device for a DC grounding system, including a giant magnetoresistance sensor, a signal processing circuit and a shielding insulation protection box; The through hole for the wires of the DC grounding system to pass through. The giant magnetoresistance sensor is connected with the signal processing circuit and fixed in the shielding insulation protection box; direction, so that the magnetic field in the direction of the sensitive axis is proportional to the current amplitude in the conductor of the DC grounding system;

The giant magnetoresistance sensor includes a micro piezoelectric bridge, a giant magnetic sensitive element, an insulating substrate and a gasket on the insulating substrate, the micro piezoelectric bridge includes a base, a bridge body and a piezoelectric sheet, and the base includes The first base and the second base are fixed on both ends of the insulating base by gaskets, the bridge body is connected between the first base and the second base, the piezoelectric sheet is arranged on the bridge body and Located between the first base and the second base; the giant magnetic sensitive elements are arranged under the bridge body and arranged symmetrically along the centerline of the bridge body, and the giant magnetic sensitive elements include giant magnetic sensitive elements connected in series through metal electrodes A magnetoresistance sensing unit and a giant magnetoresistance sensing unit, the other end of the giant magnetoresistance sensing unit has a first electrode as the input or output electrode of the entire giant magnetoresistance sensor, the other end of the giant magnetoresistance sensing unit One end has a second electrode as the output or input electrode of the entire giant magnetoresistance sensor.

Further, the piezoelectric sheet is made of a thin piezoelectric ceramic sheet with a rectangular shape, the width of the piezoelectric sheet is consistent with the width of the bridge body, and the two ends of the piezoelectric sheet are spaced from the base, and the distance is The bases are at equal distances.

Further, the thickness of the bridge body is half of the thickness of the base.

Further, the signal processing circuit includes an amplification module, a logic analysis module, and a LoRa wireless communication module connected in sequence, and the signal processing circuit also includes a power module and a clock module, and the power module is connected to the giant magnetoresistance sensor, Amplification module, logic analysis module, LoRa wireless communication module and clock module are connected, and described clock module is connected with logic analysis module and LoRa wireless communication module respectively; Suppress common mode interference; the logic analysis module is used for real-time analysis and processing of the signal flowing through the amplification module, restores the amplitude of the current flowing through the DC ground electrode, and packages the analysis results according to the LoRa wireless communication protocol and regularly or in an abnormal state Wake up the LoRa wireless communication module for long-distance data transmission, and send the current information in the wire of the DC grounding system to the remote substation; the power module is used to provide power supply voltage signals for all modules; the clock module is used for logic analysis The module and the LoRa wireless communication module provide clock signals.

Further, the shell of the shielding insulation protection box has a three-layer structure, the outermost layer uses a material with high electrical conductivity to shield the interference of high-frequency electromagnetic waves, and the innermost layer uses a material with high magnetic permeability to shield the magnetic field generated by the nearby DC wire; The middle layer is isolated by insulating materials; the shielding insulation protection box is used to provide mechanical protection, insulation protection and electromagnetic shielding for the internal structure, effectively ensuring that the current monitoring device of the DC grounding system works normally outdoors for a long time.

Compared with the prior art, the current monitoring device of the DC grounding system provided by the utility model collects the current in the wire of the DC grounding system through the giant magnetoresistive sensor, and outputs a differential signal for the signal processing circuit to analyze and process, and the analysis As a result, the LoRa wireless communication module is woken up regularly or in an abnormal state for long-distance data transmission, and the current information in the wire of the DC grounding system is sent to the remote substation, so that the remote substation can monitor the status of the DC grounding system in real time; the current monitoring device of the DC grounding system is internal The structure is simple, the reliability is high, the measurement frequency and amplitude range are wide, the cost of mass production is low, the service life is long, and it is not easy to be damaged under the impact of strong electromagnetic field generated by the action of large current. It has great advantages in long-term online monitoring applications.

Description of drawings

In order to illustrate the technical solution of the utility model more clearly, the accompanying drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only an embodiment of the utility model. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a structural schematic diagram of a DC grounding system current monitoring device of the present invention;

Fig. 2 is the structural representation of the giant magnetoresistance sensor of the present utility model;

Among them: 1-DC grounding system wire, 2-giant magnetoresistance sensor, 3-amplification module, 4-logic analysis module, 5-LoRa wireless communication module, 6-clock module, 7-power supply module, 8-signal processing circuit, 9-shielding insulation protection box, 10-first base, 11-second base, 12-piezoelectric sheet, 13-giant magnetoresistance sensing unit, 14-giant magnetoresistance sensing unit, 15-metal electrode, 16 - first electrode, 17 - second electrode.

detailed description

The technical solutions in this implementation model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

As shown in Figures 1 and 2, the DC grounding system current monitoring device provided by the utility model includes a giant magnetoresistance sensor 2, a signal processing circuit 8 and a shielding insulation protection box 9; There is a through hole for the DC grounding system wire 1 to pass through, the giant magnetoresistance sensor 2 is connected with the signal processing circuit 8, and is fixed in the shielding insulation protection box 9; the sensitive axis direction of the giant magnetoresistance sensor 2 is along the The tangential direction of the conductor 1 of the DC grounding system makes the magnetic field in the direction of the sensitive axis proportional to the current amplitude in the conductor 1 of the DC grounding system;

The giant magnetoresistive sensor 2 includes a micro piezoelectric bridge, a giant magnetic sensitive element, an insulating base and a gasket positioned on the insulating base, and the micro piezoelectric bridge includes a base, a bridge body and a piezoelectric sheet 12, and the base The seat includes a first base 10 and a second base 11, and is fixed on both ends of the insulating base by gaskets, the bridge body is connected between the first base 10 and the second base 11, and the piezoelectric The sheet 12 is arranged on the bridge body and is located between the first base 10 and the second base 11; the giant magnetic sensitive element is arranged under the bridge body and arranged symmetrically along the centerline of the bridge body, and the giant magnetic sensitive element The element includes a giant magnetoresistance sensing unit 13 and a giant magnetoresistance sensing unit 14 connected in series through a metal electrode 15, and the other end of the giant magnetoresistance sensing unit 13 has a first electrode 16 as the entire giant magnetoresistance sensor 2. As an input or output electrode, the other end of the giant magnetoresistance sensing unit 14 has a second electrode 17 as an output or input electrode of the entire giant magnetoresistance sensor 2 .

Described signal processing circuit 8 comprises amplification module 3, logical analysis module 4, LoRa wireless communication module 5 that are connected in sequence, and described signal processing circuit 8 also comprises power supply module 7 and clock module 6, and described power supply module 7 and described Giant magnetoresistance sensor 2, amplification module 3, logic analysis module 4, LoRa wireless communication module 5 and clock module 6 are connected, and described clock module 6 is connected with logic analysis module 4 and LoRa wireless communication module 5 respectively.

The shell of the shielding insulation protection box 9 is a three-layer structure, the outermost layer adopts a material with high electrical conductivity to shield the interference of high-frequency electromagnetic waves, and the innermost layer adopts a high magnetic permeability material to shield the magnetic field generated by the nearby DC wire; the middle layer Insulation material is used for isolation; the shielding insulation protection box 9 is used to provide mechanical protection, insulation protection and electromagnetic shielding for the internal structure, effectively ensuring that the current monitoring device of the DC grounding system works normally outdoors for a long time; The shielding insulation protection box 9 is flexibly fixed on the DC grounding system conductor 1, and the relative position of the two remains unchanged, effectively ensuring the stability of the measurement results.

The selected giant magnetoresistance sensor 2 measures the magnetic field within ±1000 Oe and has a sensitivity of 0.3 mV/V/Oe. Just fix the giant magnetoresistance sensor 2 at a position 2cm away from the DC grounding system conductor, and you can measure currents up to 10kA and as low as 1.5A. If you need to further expand the range, you only need to move the giant magnetoresistance sensor 2 further away from the DC grounding system Wire 1 is enough. The frequency measurement range of the selected giant magnetoresistance sensor 2 is from DC to 20 MHz, and the selected giant magnetoresistance sensor 2 can cover the measurement requirements in both the amplitude range and the frequency range.

What is disclosed above is only the specific embodiment of the present utility model, but the scope of protection of the present utility model is not limited thereto. Any skilled person familiar with the technical field can easily think of changes or modifications within the technical scope disclosed by the utility model. Variations should be covered within the protection scope of the present utility model.

Claims (6)

1. A current monitoring device for a DC grounding system, characterized in that it includes a giant magnetoresistance sensor (2), a signal processing circuit (8) and a shielding insulation protection box (9); on the shielding insulation protection box (9) There is a through hole for the DC grounding system wire (1) to pass through, the giant magnetoresistance sensor (2) is connected with the signal processing circuit (8), and is fixed in the shielding insulation protection box (9); The direction of the sensitive axis of the magnetoresistive sensor (2) is along the tangential direction of the conductor of the DC grounding system, so that the magnetic field in the direction of the sensitive axis is proportional to the current amplitude in the conductor (1) of the DC grounding system; The giant magnetoresistance sensor (2) includes a micro-piezoelectric bridge, a giant magnetic sensitive element, an insulating substrate, and a spacer on the insulating substrate, and the micro-piezoelectric bridge includes a base, a bridge body, and a piezoelectric sheet (12) , the base includes a first base (10) and a second base (11), and is fixed on both ends of the insulating base by gaskets, and the bridge body is connected to the first base (10) and the second base Between the bases (11), the piezoelectric sheet (12) is set on the bridge body and between the first base (10) and the second base (11); the giant magnetic sensitive element is set on the bridge body below and arranged symmetrically along the midline of the bridge body, the giant magnetic sensitive element includes a giant magnetoresistance sensing unit (13) and a giant magnetoresistance sensing unit (14) connected in series through a metal electrode (15). The other end of the giant magnetoresistance sensing unit (13) has a first electrode (16) as the input or output electrode of the entire giant magnetoresistance sensor (2), and the other end of the giant magnetoresistance sensing unit (14) has The second electrode (17) serves as the output or input electrode of the entire giant magnetoresistance sensor (2). 2. The current monitoring device for DC grounding system according to claim 1, characterized in that: the piezoelectric sheet (12) is made of a thin piezoelectric ceramic sheet with a rectangular shape, and the width of the piezoelectric sheet (12) is the same as that of the piezoelectric sheet (12). The width of the bridge body is consistent, and the two ends of the piezoelectric sheet (12) are spaced from the base, and the distance from the base is equal. 3. The current monitoring device for a DC grounding system according to claim 1, wherein the thickness of the bridge body is half of the thickness of the base. 4. The current monitoring device for DC grounding system according to claim 1, characterized in that: the signal processing circuit (8) includes an amplification module (3), a logic analysis module (4), a LoRa wireless communication module ( 5), the signal processing circuit (8) also includes a power module (7) and a clock module (6), the power module (7) is connected to the giant magnetoresistance sensor (2), the amplification module (3), The logic analysis module (4), the LoRa wireless communication module (5) and the clock module (6) are connected, and the clock module (6) is respectively connected with the logic analysis module (4) and the LoRa wireless communication module (5). 5. The current monitoring device for DC grounding system according to claim 1, characterized in that: the shell of the shielding insulation protection box (9) has a three-layer structure, and the outermost layer is made of a material with high conductivity to shield high-frequency electromagnetic waves Interference, the innermost layer uses high-permeability materials to shield the magnetic field generated by nearby DC wires; the middle layer uses insulating materials for isolation. 6. The current monitoring device for DC grounding system according to claim 1, characterized in that: the magnetic field measurement range of the giant magnetoresistance sensor (2) is ±1000 Oe, the sensitivity is 0.3 mV/V/Oe; the frequency measurement range is DC to 20MHz.