Method for measuring alternating current resistance of overhead conductor

Abstract

The invention provides an overhead conductor alternating current resistance measuring method which comprises the following steps: S1, arranging a Rogowski coil on an overhead conductor, acquiring current flowing through the overhead conductor based on electromagnetic induction, sampling induced current of the Rogowski coil through a current sampling circuit, and outputting the sampled induced current to a processing unit; s2, a voltage transformer is arranged on the overhead conductor and used for obtaining the alternating voltage of the overhead conductor, and a voltage sampling circuit determines a voltage sampling signal and outputs the voltage sampling signal to a processing unit; s3, detecting the environment temperature of the current overhead conductor and outputting the environment temperature to a processing unit; and S4, the processing unit obtains the AC resistance of the current overhead conductor according to the current sampling signal, the voltage sampling signal, the conductor temperature and the environment temperature by adopting a least square method.

Description

Technical Field

[0001] The invention relates to a method for monitoring electric power equipment, and in particular to a method for measuring the AC resistance of an overhead conductor. Background Art

[0002] As a key factor affecting the operating efficiency of overhead conductors, the AC resistance of conductors is directly related to their power transmission capacity and resistance losses. Optimizing AC resistance can significantly improve power transmission efficiency, so accurate measurement is of both scientific value and practical importance.

[0003] Due to the complex structure, multi-layer and twisted conductors, the AC resistance is not only affected by the inherent characteristics of the conductor itself, but also by ambient temperature fluctuations, making it impossible to accurately measure. The measurement methods in the prior art do not take into account the impact of ambient temperature fluctuations. In addition, the existing voltage and current measurement methods require establishing an electrical connection between the conductors, which requires destroying the structure of the conductors themselves, thereby further reducing the measurement accuracy.

[0004] Therefore, in order to solve the above technical problems, it is urgent to propose a new technical means. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method for measuring the AC resistance of an overhead conductor, which performs sampling based on the principle of electromagnetic induction when obtaining the current and voltage signals of the overhead conductor, thereby reducing damage to the overhead conductor structure and taking into account the influence of ambient temperature at the same time. It can effectively ensure the final measurement accuracy of the AC resistance of the overhead conductor and provide accurate data support for subsequent power transmission.

[0006] The present invention provides a method for measuring AC resistance of an overhead conductor, comprising:

[0007] S1. A Rogowski coil is provided on the overhead conductor, and the current flowing through the overhead conductor is obtained based on electromagnetic induction. The induced current of the Rogowski coil is sampled by a current sampling circuit and output to a processing unit;

[0008] S2. A voltage transformer is provided on the overhead line for obtaining the AC voltage of the overhead conductor, and the voltage sampling circuit determines the voltage sampling signal and outputs it to the processing unit;

[0009] S3. Detect the current ambient temperature of the overhead wire and output it to the processing unit;

[0010] S4. The processing unit obtains the current AC resistance of the overhead conductor according to the current sampling signal, the voltage sampling signal, the conductor temperature and the ambient temperature by using the least square method.

[0011] Further, the current sampling circuit includes a rectifier circuit REC1, a resistor R1, a capacitor C1, a resistor R4, an operational amplifier U1, a resistor R2, a resistor R3 and a current sampling chip;

[0012] The positive input terminal and the negative input terminal of the rectifier circuit REC1 are respectively connected to the two ends of the Rogowski coil, the negative output terminal of the rectifier circuit REC1 is grounded, the positive output terminal of the rectifier circuit is connected to the ground after being connected in series with the resistor R1 and the resistor R4, the common connection point between the resistor R1 and the resistor R4 is connected to the in-phase terminal of the operational amplifier U1, the inverting terminal of the operational amplifier U1 is directly connected to the output terminal of the operational amplifier U1, the output terminal of the operational amplifier U1 is connected to the ground after being connected in series with the resistor R2 and the resistor R3, the common connection point between the resistor R2 and the resistor R3 is connected to the input terminal of the current sampling chip, and the output terminal of the current sampling chip is connected to the processing unit.

[0013] Further, the voltage sampling unit includes a rectifier circuit REC2, a capacitor C2, a voltage regulator tube DW2, an operational amplifier U2, a resistor R5, a resistor R6 and a capacitor C3;

[0014] The positive input terminal and the negative input terminal of the rectifier circuit REC2 are respectively connected to the two ends of the secondary winding of the voltage transformer, the negative output terminal of the rectifier circuit REC2 is grounded, the positive output terminal of the rectifier circuit REC2 is grounded through the capacitor C2, the positive output terminal of the rectifier circuit REC2 is connected to the negative electrode of the voltage regulator tube DW1, the positive electrode of the voltage regulator tube DW1 is grounded, the positive output terminal of the rectifier circuit REC2 is connected to the in-phase terminal of the operational amplifier U2, the inverting terminal of the operational amplifier U2 is directly connected to the output terminal of the operational amplifier U2, the output terminal of the operational amplifier U2 is connected in series with the resistor R6 and the resistor R5 and then grounded, the common connection point of the resistor R6 and the resistor R5 is grounded through the capacitor C3, the common connection point of the resistor R6 and the resistor R5 is connected to the input terminal of the voltage sampling chip, and the output terminal of the voltage sampling chip is connected to the processing unit.

[0015] Further, the processing unit includes a processing chip, a wireless communication module and a location module;

[0016] The input end of the processing chip is connected to the output end of the current sampling circuit, the voltage sampling circuit and the temperature sensor. The processing chip is connected to the remote monitoring host through the wireless communication module, and the position module is connected to the processing chip.

[0017] Furthermore, the wireless communication module is a 2.4G power wireless private network module or a 5G module.

[0018] Furthermore, the location module is a Beidou positioning module or a GPS positioning module.

[0019] The beneficial effects of the present invention are as follows: through the present invention, sampling is performed based on the principle of electromagnetic induction when obtaining current and voltage signals of overhead conductors, thereby reducing damage to the structure of the overhead conductors. Meanwhile, the influence of ambient temperature is taken into consideration, and the final measurement accuracy of the AC resistance of the overhead conductors can be effectively ensured, providing accurate data support for subsequent power transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0021] Figure 1 It is a flow chart of the present invention.

[0022] Figure 2 It is a structural block diagram of the present invention.

[0023] Figure 3 This is a schematic diagram of the current sampling circuit of the present invention.

[0024] Figure 4 It is the principle diagram of the voltage sampling circuit of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below:

[0026] The present invention provides a method for measuring AC resistance of an overhead conductor, comprising:

[0027] S1. A Rogowski coil is provided on the overhead conductor, and the current flowing through the overhead conductor is obtained based on electromagnetic induction. The induced current of the Rogowski coil is sampled by a current sampling circuit and output to a processing unit;

[0028] S2. A voltage transformer is provided on the overhead line for obtaining the AC voltage of the overhead conductor, and the voltage sampling circuit determines the voltage sampling signal and outputs it to the processing unit;

[0029] S3. Detect the current ambient temperature of the overhead wire and output it to the processing unit;

[0030] S4. The processing unit obtains the AC resistance of the current overhead conductor by the least square method according to the current sampling signal, the voltage sampling signal, the conductor temperature and the ambient temperature and uploads it to the remote monitoring host. The ambient temperature is obtained by the existing temperature sensor; the process of determining the AC resistance by the least square method can be carried out by the existing technology, which will not be described in detail here. Through the present invention, sampling is performed based on the principle of electromagnetic induction when obtaining the current and voltage signals of the overhead conductor, thereby reducing the damage to the overhead conductor structure, and taking into account the influence of the ambient temperature at the same time, it can effectively ensure the final measurement accuracy of the AC resistance of the overhead conductor and provide accurate data support for subsequent power transmission.

[0031] In this embodiment, the current sampling circuit includes a rectifier circuit REC1, a resistor R1, a capacitor C1, a resistor R4, an operational amplifier U1, a resistor R2, a resistor R3 and a current sampling chip;

[0032] The positive input terminal and the negative input terminal of the rectifier circuit REC1 are respectively connected to the two ends of the Rogowski coil, the negative output terminal of the rectifier circuit REC1 is grounded, the positive output terminal of the rectifier circuit is connected to the ground after being connected in series with the resistor R1 and the resistor R4, the common connection point between the resistor R1 and the resistor R4 is connected to the in-phase terminal of the operational amplifier U1, the inverting terminal of the operational amplifier U1 is directly connected to the output terminal of the operational amplifier U1, the output terminal of the operational amplifier U1 is connected to the ground after being connected in series with the resistor R2 and the resistor R3, the common connection point between the resistor R2 and the resistor R3 is connected to the input terminal of the current sampling chip, and the output terminal of the current sampling chip is connected to the processing unit. Through the above structure, the accurate current of the overhead wire can be determined for accurate sampling.

[0033] In this embodiment, the voltage sampling unit includes a rectifier circuit REC2, a capacitor C2, a voltage regulator tube DW2, an operational amplifier U2, a resistor R5, a resistor R6 and a capacitor C3;

[0034] The positive input terminal and the negative input terminal of the rectifier circuit REC2 are respectively connected to the two ends of the secondary winding of the voltage transformer, the negative output terminal of the rectifier circuit REC2 is grounded, the positive output terminal of the rectifier circuit REC2 is grounded through the capacitor C2, the positive output terminal of the rectifier circuit REC2 is connected to the negative electrode of the voltage regulator tube DW1, the positive electrode of the voltage regulator tube DW1 is grounded, the positive output terminal of the rectifier circuit REC2 is connected to the in-phase terminal of the operational amplifier U2, the inverting terminal of the operational amplifier U2 is directly connected to the output terminal of the operational amplifier U2, the output terminal of the operational amplifier U2 is connected in series with the resistor R6 and the resistor R5 and then grounded, the common connection point of the resistor R6 and the resistor R5 is grounded through the capacitor C3, the common connection point of the resistor R6 and the resistor R5 is connected to the input terminal of the voltage sampling chip, and the output terminal of the voltage sampling chip is connected to the processing unit. Through the above structure, the voltage signal of the overhead wire can be accurately sampled.

[0035] Among them, the current sampling chip and the voltage sampling chip can use existing sampling circuits, such as SC1281, SGM58601, etc., and can be selected according to actual needs.

[0036] In this embodiment, the processing unit includes a processing chip, a wireless communication module and a location module;

[0037] The input end of the processing chip is connected to the output end of the current sampling circuit, the voltage sampling circuit and the temperature sensor. The processing chip is connected to the remote monitoring host through a wireless communication module. The location module is connected to the processing chip. The processing chip uses an existing chip, such as an STM32 series chip. The wireless communication module is a 2.4G power wireless private network module or a 5G module. The location module is a Beidou positioning module or a GPS positioning module.

[0038] In the drawings, GA1 and GA2 are both air protection gaps.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for measuring AC resistance of an overhead conductor, characterized in that: include: S1. A Rogowski coil is provided on the overhead conductor, and the current flowing through the overhead conductor is obtained based on electromagnetic induction. The induced current of the Rogowski coil is sampled by a current sampling circuit and output to a processing unit; S2. A voltage transformer is provided on the overhead line for obtaining the AC voltage of the overhead conductor, and the voltage sampling circuit determines the voltage sampling signal and outputs it to the processing unit; S3. Detect the current ambient temperature of the overhead wire and output it to the processing unit; S4. The processing unit obtains the current AC resistance of the overhead conductor according to the current sampling signal, the voltage sampling signal, the conductor temperature and the ambient temperature by using the least square method.

2. The method for measuring AC resistance of an overhead conductor according to claim 1, characterized in that: The current sampling circuit includes a rectifier circuit REC1, a resistor R1, a capacitor C1, a resistor R4, an operational amplifier U1, a resistor R2, a resistor R3 and a current sampling chip; The positive input terminal and the negative input terminal of the rectifier circuit REC1 are respectively connected to the two ends of the Rogowski coil, the negative output terminal of the rectifier circuit REC1 is grounded, the positive output terminal of the rectifier circuit is connected to the ground after being connected in series with the resistor R1 and the resistor R4, the common connection point between the resistor R1 and the resistor R4 is connected to the in-phase terminal of the operational amplifier U1, the inverting terminal of the operational amplifier U1 is directly connected to the output terminal of the operational amplifier U1, the output terminal of the operational amplifier U1 is connected to the ground after being connected in series with the resistor R2 and the resistor R3, the common connection point between the resistor R2 and the resistor R3 is connected to the input terminal of the current sampling chip, and the output terminal of the current sampling chip is connected to the processing unit.

3. The method for measuring AC resistance of overhead conductor according to claim 1, characterized in that: The voltage sampling unit includes a rectifier circuit REC2, a capacitor C2, a voltage regulator tube DW2, an operational amplifier U2, a resistor R5, a resistor R6 and a capacitor C3; The positive input terminal and the negative input terminal of the rectifier circuit REC2 are respectively connected to the two ends of the secondary winding of the voltage transformer, the negative output terminal of the rectifier circuit REC2 is grounded, the positive output terminal of the rectifier circuit REC2 is grounded through the capacitor C2, the positive output terminal of the rectifier circuit REC2 is connected to the negative electrode of the voltage regulator tube DW1, the positive electrode of the voltage regulator tube DW1 is grounded, the positive output terminal of the rectifier circuit REC2 is connected to the in-phase terminal of the operational amplifier U2, the inverting terminal of the operational amplifier U2 is directly connected to the output terminal of the operational amplifier U2, the output terminal of the operational amplifier U2 is connected in series with the resistor R6 and the resistor R5 and then grounded, the common connection point of the resistor R6 and the resistor R5 is grounded through the capacitor C3, the common connection point of the resistor R6 and the resistor R5 is connected to the input terminal of the voltage sampling chip, and the output terminal of the voltage sampling chip is connected to the processing unit.

4. The method for measuring AC resistance of overhead conductor according to claim 1, characterized in that: The processing unit includes a processing chip, a wireless communication module and a location module; The input end of the processing chip is connected to the output end of the current sampling circuit, the voltage sampling circuit and the temperature sensor. The processing chip is connected to the remote monitoring host through the wireless communication module, and the position module is connected to the processing chip.

5. The method for measuring AC resistance of overhead conductor according to claim 4, characterized in that: The wireless communication module is a 2.4G power wireless private network module or a 5G module.

6. The method for measuring AC resistance of overhead conductor according to claim 4, characterized in that: The location module is a Beidou positioning module or a GPS positioning module.

Images