CN111413893A - A wireless current acquisition system for startup and debugging of ultra-high voltage power transmission and transformation projects - Google Patents

Abstract

The invention discloses a wireless current acquisition system for starting and debugging an ultra-high voltage power transmission and transformation project, which comprises a current acquisition module, a power transmission and transformation circuit and a power transmission and transformation circuit, wherein the current acquisition module is used for sensing secondary current of a main transformer and outputting corresponding weak voltage signals; the signal acquisition module is used for sampling the voltage signal and converting the sampled signal into a data frame with a timestamp; and the data frame with the time stamp is sent to the user side by the wireless module. The wireless current acquisition device adopts the open-close type current probe and the wireless data transmission, replaces a cable used for measurement and transmission in the prior art, not only saves a large amount of paying-off work, but also avoids the safety risk of the traditional measurement mode and improves the safety.

Description

A wireless current acquisition system for startup and debugging of ultra-high voltage power transmission and transformation projects

technical field

The invention relates to a wireless current acquisition system for start-up and debugging of ultra-high voltage power transmission and transformation projects, belonging to the field of start-up and debugging of ultra-high-voltage power transmission and transformation projects.

Background technique

Before the new power transmission and transformation project is put into operation, in order to evaluate the insulation performance of the line and the substation and the performance of the transformer to avoid the inrush current, it is necessary to close and open the line and the transformer to simulate the electromagnetic transient process of the system operation. During the test, it is necessary to measure the closing inrush current of the line and the main transformer, so as to grasp the closing overcurrent of the line and the transformer, and evaluate the ability of the relevant protection to avoid the closing inrush current.

The traditional current measurement and recording device and method need to connect the current signal line in series to the CT secondary circuit in the station. This wiring method has the following problems: First, the wiring workload is large, time-consuming and laborious. If improper operation or accidental disconnection occurs, it can be The open circuit of the CT secondary circuit will seriously threaten the safety of personnel and equipment; the second is that the signal cables are all over the channels of the relay protection room, which are easily damaged and lead to the loss of transient signals, which will seriously affect the test process; Connection, the signal cable is easily pulled and the equipment in the relay protection room is damaged. The power transmission and transformation project start-up debugging test is the last stage of the equipment network test. The test results directly affect the safe operation of the equipment. The existing current measurement and recording methods have a great impact on the safety of personnel and power equipment.

SUMMARY OF THE INVENTION

Purpose of the invention: The present invention proposes a wireless current acquisition system for startup and debugging of ultra-high voltage power transmission and transformation projects, so as to improve the work efficiency and safety and reliability of the test.

Technical scheme: The technical scheme adopted in the present invention is a wireless current acquisition system for startup and debugging of ultra-ultra-high voltage power transmission and transformation projects, including a current acquisition module that senses the secondary current of power transmission and transformation lines or transformers and outputs corresponding weak voltage signals; The voltage signal is sampled, and the sampled signal is converted into a signal acquisition module with time-stamped data frames; the time-stamped data frames are sent to the user side.

Also includes a power module to power the current acquisition system.

The power module includes a built-in lithium battery and a remote switch module, and both the external power supply and the lithium battery are connected to the remote switch module.

The current acquisition module adopts a hybrid sampling probe composed of a transformer coil based on Faraday's law and a Hall sensor based on Hall effect, a resistive voltage divider network for phases A, B and C, and an isolated operational amplifier.

The signal acquisition module includes a signal conditioning module, an analog-to-digital converter, a control acquisition and time stamp unit, a framing and a sending unit.

The control acquisition and time stamping unit adopts a programmable on-chip system, which contains two modules of ARM and FPGA.

The framing and sending unit forms a data frame with time stamp by framing the acquired current data of the power transmission and transformation line or transformer and the time stamp.

It also includes a wireless module, and the data frame with time stamp is sent to the user side by the wireless module.

The wireless module is a 5Ghz wireless bridge.

Beneficial effects: The wireless current acquisition device of the present invention adopts an open-close current probe, which replaces the measurement in the prior art, avoids the safety risk of the traditional measurement method, and improves the safety. At the same time, the present invention also adopts wireless data transmission, which replaces the cables used for transmission and saves a lot of work of paying out the wires. In addition, because the present invention adopts wireless transmission and control mode, the work of manually connecting the current signal line in series to the CT secondary circuit in the station is avoided, and the work efficiency of the test is improved.

Description of drawings

1 is a structural block diagram of Embodiment 1;

Fig. 2 is the structural representation of embodiment 1;

3 is a structural block diagram of Embodiment 2;

FIG. 4 is a schematic structural diagram of Embodiment 2. FIG.

Detailed ways

Below in conjunction with the accompanying drawings and specific embodiments, the present invention will be further clarified. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Modifications of equivalent forms all fall within the scope defined by the appended claims of this application.

Example 1

As shown in FIG. 1 , the present invention includes a current acquisition module, a signal acquisition module, and a transmission module. The current acquisition module uses an open-close current probe to obtain the secondary current of the power transmission and transformation line or transformer, and the open-close current probe is a hybrid of a transformer coil based on Faraday's law and a Hall sensor based on the Hall effect. sampling probe. The open-close current probe has an openable and closeable measuring magnetic core. When measuring the current of power transmission and transformation lines or transformers, the magnetic core is sleeved on the secondary circuit of the corresponding current transformer. form a toroidal magnetic field. The Hall sensor is embedded in the magnetic core, and the strength of the fixed magnetic field and the low-frequency magnetic field in the magnetic core can be measured by measuring the voltage across the Hall crystal flowing through a certain current; The coil can measure the strength of the high-frequency magnetic field, and the output voltages of the two are mixed to form the final output. Therefore, the magnetic field strength in the original magnetic core can be measured by measuring the output voltage of the current probe, and the magnitude of the measured current can be obtained by inversely deriving the fixed ratio of the magnetic field strength of the magnetic core and the measured current. The open-close current probe is not physically connected to the power transmission line or the secondary circuit of the transformer, which avoids the risk of the secondary circuit being open. According to the aforementioned principles, the current acquisition module measures the currents of phases A, B and C of the grid. In addition, as shown in Figure 2, the current acquisition module also includes the resistive voltage divider network and isolation op amp for the A, B and C phases. The voltage signals of each phase output by the open-close current probe are then input to the signal acquisition module after passing through the resistor divider network and the isolation operational amplifier of the A, B and C phases in sequence.

The signal acquisition module includes a signal conditioning module, an analog-to-digital converter, a control acquisition and time stamp unit, and a framing and sending unit. The resistor divider network is used to adjust the amplitude of the input signal to match the input amplitude of the isolation operational amplifier. Isolation op amps prevent external high-voltage signals and surges from interfering with the work of internal equipment or causing damage to internal equipment. Then, the signal conditioning module in the signal acquisition module adjusts the amplitude of the voltage signal to match the input range of the subsequent analog-to-digital converter. Then, the analog-to-digital converter in the signal acquisition module samples the voltage signals of each phase after the amplitude adjustment to obtain a digital voltage signal, and then calculates the magnitude of the measured current from the transformation ratio of the current probe. The analog-to-digital converter uses AD7606.

The control acquisition and time stamping unit adopts SOPC (system on a programmable chip), which contains two modules of ARM and FPGA, wherein the FPGA module controls the analog-to-digital converter according to the time and second pulse signal provided by the GPS/Beidou module. The GPS/Beidou signal comes from an external GPS/Beidou antenna. The FPGA module controls the analog-to-digital converter to sample 200K times between the rising edges of two adjacent second pulses, that is, the sampling frequency of 200KHz, and at the same time marks each sampled signal and sends it to the ARM module. The ARM module runs the Linux operating system, and its built-in driver realizes reading the digital voltage signal obtained by sampling from the FPGA, receiving the control instructions controlled by the host computer, supporting RMS sudden change triggering, and triggering the signal threshold value as a trigger method to trigger the packaging and return of the digital voltage signal. , digital voltage signal data is packaged back to the host computer and other functions. When the GPS/Beidou signal is stably locked, it is used as the time reference source for synchronous acquisition between the acquisition devices, and the SOPC samples the A, B and C three-phase voltage signals according to the time reference. When the GPS/Beidou signal changes from a stable lock to an out-of-lock state, the time stamping unit can perform local self-locking based on the local high-precision crystal oscillator and algorithm, and the local 4-hour synchronization loss-of-lock error is controlled within 50us. The framing and sending unit will frame the current data of the transmission and transformation lines or transformers and the time stamp to form a data frame with a time stamp. At the same time, a data frame with the same content will be stored in the device and retained as a backup file.

The transmission module can be a wireless module, specifically, a 5Ghz wireless bridge can be used to transmit the time frame back to the central user side, and display the current waveform on the terminal display screen to realize distributed current collection. Therefore, the device realizes the functions of unmanned measurement and wireless transmission of current information of power transmission and transformation lines or transformers.

Example 2

As shown in FIG. 3 , this embodiment includes all the contents of Embodiment 1, in addition to which a power supply module is also provided. Specifically, as shown in FIG. 4 , the power module supplies power to the entire device, which includes a built-in 24V/10AH lithium battery and a remote switch module. Either a 24V/10AH lithium battery can be used, or an external power supply can be used as the power supply. The lithium battery and the external power supply are connected to the remote switch module through the power selection switch. When using the device, first select lithium battery or external power supply as the power supply through the local power selection switch. After the device is working, the user can control the remote switch module through the LORA communication protocol to control the system to stand by or work. The built-in lithium battery can support the device to work continuously on site for 20 hours and stand by for 70 hours.

Claims (9)

1. A wireless current collection system for starting debugging of an ultra-high voltage power transmission and transformation project is characterized by comprising a current collection module for sensing secondary current of a power transmission and transformation line or a main transformer and outputting corresponding weak voltage signals; the signal acquisition module is used for sampling the voltage signal and converting the sampled signal into a data frame with a timestamp; the time-stamped data frame is sent to the user side.

2. The wireless current collection system for starting debugging of extra-high voltage power transmission and transformation project of claim 1, further comprising a power module for supplying power to the current collection system.

3. The system for collecting radio current for starting and debugging of extra-high voltage power transmission and transformation project of claim 2, wherein the power module comprises a built-in lithium battery and a remote switch module, and an external power supply and the lithium battery are both connected to the remote switch module.

4. The wireless current collection system for starting and debugging of extra-high voltage power transmission and transformation engineering according to claim 1, wherein the current collection module adopts a mixed sampling probe formed by combining a mutual inductor coil based on Faraday's law and a Hall sensor based on Hall effect, A, B and a C-phase resistance voltage division network and an isolation operational amplifier.

5. The system for collecting radio current for startup debugging of extra-high voltage power transmission and transformation project of claim 1, wherein the signal collection module comprises a signal conditioning module, an analog-to-digital converter, a control collection and time scale unit, and a framing and sending unit.

6. The system for collecting radio current for starting debugging of extra-high voltage transmission and transformation project of claim 5, wherein the control collection and time scale unit is a programmable system on chip which contains two modules of ARM and FPGA.

7. The system of claim 5, wherein the framing and transmitting unit frames the acquired power transmission and transformation line current data and time stamps into time-stamped data frames.

8. The system for collecting radio current for startup debugging of extra-high voltage power transmission and transformation project of claim 1, further comprising a wireless module, wherein the data frame with the timestamp is sent to a user side by the wireless module.

9. The system for collecting radio current for startup debugging of ultra-high voltage electric transmission and transformation project of claim 8, wherein the wireless module is a 5Ghz wireless network bridge.

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