HYXJZ small current grounding intelligent line selection device

2021-03-11 09:07:40

Times

Content：

1. Introduction to the device

Single-phase grounding is the most common fault in medium-voltage distribution networks. Although the system can continue to operate with faults after grounding, due to the rise of non-faulty relative to ground voltage, it may develop into a non-faulty phase insulation damage relay if it is not handled in time. There is a threat of short-circuit between phases. Timely and accurately determining the ground loop is the basis for quickly eliminating single-phase ground faults. The protection device that realizes the determination of the ground fault loop is usually called the low-current grounding line selection device, but the early line selection devices often misselected and missed the selection. Unsatisfactory.

HYXJZ low current grounding line selection device is a supporting product of a new generation of substation automation system independently researched and developed by our company. The product adopts the comprehensive line selection theory based on the comparison of the transient zero sequence current amplitude, through high-speed sampling, extracts and analyzes the harmonic components of the transient zero sequence current at the moment of grounding, and uses the unique characteristics of the characteristic frequency band to identify the faulty line . This line selection theory requires strong hardware platform support, so this device adopts MCU+ARM structure, ARM is responsible for man-machine and communication management, and MCU completes line selection tasks.

2. Model description

3. Device features

3.1 Powerful and stable hardware platform; a) ARM system, protection and monitoring are relatively independent, more stable and reliable; b) Samsung mainstream 32-bit microprocessor, powerful data processing and logic operation capabilities; c) 12 16-bit AD, weekly wave 512 points simultaneous sampling; d) Powerful FPGA, which controls AD sampling and realizes logic programming export; e) Ethernet + RS485 communication mode, each communication channel is completely independent; f) With printing function, local printing can be realized (this function Optional); g) Full touch screen design, no buttons on the panel, more reliable.

3.2 Embedded real-time multi-tasking operating system; a) Using embedded real-time multi-tasking operating system linux, the most effective management of hardware resources; b) Fully meet the real-time requirements of the power system.

3.3 Humanized design concept; a) Full-Chinese touch color LCD screen display, simple and convenient operation, providing full online help menu and graphical, tabular output interface; b) Multiple sets of protection settings can be set independently. Online setting and switching are completely convenient; c) Plug-and-play design concept; d) Application of comprehensive process reproduction technology; e) Real-time voltage and current waveform display; f) Beautiful appearance design suitable for industry.

3.4 The conceptual design of adjustment-free and easy maintenance; a) The whole machine has no adjustable components, and selects high-precision, high-stability industrial-grade components to ensure high accuracy in normal operation and avoid increased sampling errors caused by environmental changes or long-term operation Large; b) With a complete self-check function, the device can be located abnormally to the chip;

3.5 Specialized structural design; a) The device adopts the whole panel back-plug structure design, the strong and the weak current are completely separated, and the electromagnetic compatibility is excellent; b) The whole machine has good sealing performance, and the careful dust-proof and seismic design can realize full dispersion. Installation does not require any external anti-jamming devices; c) Modular design of functions, the increase, decrease and movement of functions can be realized through plug-in plug-in, plug and play.

3.6 Wide application range

Suitable for neutral point ungrounded/grounded via arc suppression coil/grounded via high resistance system; suitable for overhead line/cable line system; unlimited long and short lines, unlimited number of wires running in parallel: line and bus grounding can be distinguished.

4. Technical indicators

5. Installation instructions

5.1 Device installation instructions: The device adopts a 4U high-strength chassis, and the screen installation method is embedded and rear wiring. In addition to meeting the requirements on the mechanical structure, the installation should also ensure the electrical installation requirements. Users are requested to read this section in detail.

5.1.1 Installation of zero-sequence current transformer: Most users of cable outlets use zero-sequence current transformer CT to obtain zero-sequence current. The installation of the transformer should ensure that the zero-sequence current signal is not short-circuited, as shown in the figure. The fixing bolts on the insulating board in the figure should ensure that the clip (ie, the cable sheath) is insulated from the ground. The grounding wire of the cable shell on the bus side should pass through the zero-sequence CT before grounding.

5.1.2 Three-phase CT connected to a zero-sequence filter: a. For users who have installed three-phase CT, to obtain zero-sequence current, they can be connected to a zero-sequence current filter method, because the current input loop of the device has extremely low The input impedance, therefore, does not affect the user to connect other current measurement components in series with the zero sequence current filter loop. b. For users who only have A and C two-phase CTs, B-phase CT must be installed, and its accuracy and transformation ratio must be the same as those of A and C phases, so that the device can be connected as a zero-sequence filter.

5.1.3 Requirements for the terminal with the same name (polarity): the device has no requirements for the zero-sequence voltage signal access to the terminal with the same name (except for the version containing the power direction and the integrated criterion algorithm), and the device has the same-named terminal for the zero-sequence current transformer (Also known as polarity) requires complete unanimous access to the machine. The three-phase CT is connected to the zero-sequence current filter with the same name and it is also required to be connected to the machine in unison. For systems with both zero-sequence CT and three-phase filters, the same-named terminal is also required to be completely connected to the device.

5.2 Device instructions: The device adopts a full touch screen design. Since the device uses a real-time multitasking operating system linux, it takes a long time to start up. After the device is started, it enters the main menu. The display interface will automatically close after 5 minutes without any operation. Tap the screen to automatically display it.

After the device is turned on, the interface as shown in the figure is displayed. Click any icon to enter the corresponding menu. The specific operations are as follows: