1. Product Overview

Operating system: real time Linux + RTOS. Real time operating system (real time operating system) is adopted to meet the requirements of national grid / Southern Power Grid for the operation system of line selection device, and the stability, security and real-time requirements of the line selection device are considered.

Hardware foundation: big data + strong computing power. The FPGA is used to realize up to 84 channels, synchronous 16 bit AD sampling, sampling frequency: 50kpps, which provides reliable data base for the related fault treatment such as grounding; High performance multi-core heterogeneous processor (dual floating point DSP c66x+ dual arm), high speed (dsp:750 MHz; ARM:1500MHz ）, and it is equipped with high-speed memory to provide computing power for data processing.

High accuracy of line selection: Based on big data + strong calculation force, steady state algorithm + transient algorithm, line selection learning algorithm, combined with effective field selection technology, and verification by "physical real type experimental system", can distinguish the complex grounding fault types such as metal grounding, transition resistance grounding less than 8000 ohm, intermittent arc grounding, etc.

The logic of line selection protection is complete: the device designs a complete logic for dealing with ground fault, which realizes the goal of accurate identification of instantaneous fault, fast isolation of permanent fault and quick recovery of power supply for non fault lines.

Powerful functions: line selection function, tripping (closing) gate, post acceleration trip, wheel cutting (leakage test) function, dual channel protection, phase determination, Pt line break judgment, fault recording, fault statistical analysis

Scalability: the device hardware design has margin, which can be used to extend the control function, and to realize the active line selection scheme similar to "resistance in parallel of arc suppression coil".

2. Product Features

Line selection function: the device has the function of grounding and line selection. When single-phase grounding occurs in the system, the device can make accurate judgment according to the acquired signal, select the fault line, and automatically return to the device after the device displays the name (number) of the grounding line and bus.

Tripping (closing) gate function: the device has the function of grounding protection tripping (closing) gate, and the tripping (closing) function can be realized by connecting the protection tripping (closing) circuit. The switching (closing) function of the device can be set independently according to different lines.

Wheel cutting function: the device has the function of wheel cutting. After the failure of the selected line trip, the device can directly start the wheel cutting function according to the device setting, and then act in sequence until the fault line is cut off to ensure the accuracy of the line selection. When the protection sensitivity is insufficient (line selection protection setting value > 3U0 > wheel cut setting value), the wheel cutting function (long time wheel cutting) can be started by delay. The function can be switched on and off, the delay can be set, and whether each line participates in wheel cutting can be set independently. The wheel cutting (leakage test) strategy can be adjusted, and it has two modes: fixed wheel cutting and automatic wheel cutting.

Post acceleration trip function: the device has the function of post acceleration tripping. When the selected line trips successfully and coincides with permanent fault (if line reclosing is put into operation), the device can accelerate tripping to cut off the fault line, and the function can be switched on and off.

Phase determination function: the device has the function of phase determination of single-phase ground fault, which can accurately judge the phase of ground fault.

PT break judgment function: the device has the function of Pt breaking, which can distinguish Pt primary break and PT secondary disconnection. The selection strategy under the condition of broken line can be set.

Ferroresonance alarm function: the device has the function of ferroresonance alarm. When the system has ferroresonance, the device can accurately identify and simultaneously alarm signal of ferroresonance.

Fault statistics function: the device has the statistical function of instantaneous grounding and permanent grounding times of each line, which provides the basis for analyzing the operation status of the line.

Adaptive function of operation condition: the device can make judgment according to the change of field operation condition, such as the position change of section switch and connecting switch of ring network structure, so as to ensure the correct action of the line selection device.

Self inspection function: the device has the function of online automatic detection. During normal operation, when a single electronic component in the device is damaged (except for the outlet relay), it sends out abnormal signal of the device without misoperation.

Fault recording function: the device has fault recording function. When the system has single-phase ground fault, the data of 80ms before the fault and 120ms after the fault occurs are taken. The data of 80ms before the first line selection trip and 120ms after the first line selection trip time are recorded with the recording resolution of 120 points per week; the recording format of the recording file adopts the standard comtrace99 format, which supports the Ethernet through Ethernet The recording file is extracted by the interface and debugging interface.

Communication function: the device adopts the communication protocol in accordance with dl/t 860 substation communication network and system (IEC 61850), and the code of implementation of DL / T860 project of relay protection information system main station sub station, and communicates with substation automation system and telecontrol equipment.

Time synchronization function: the device has the time synchronization function (including B code timing and network timing), and the error shall not be greater than 1 ms. If all the time synchronization signals disappear, the clock of the line selection device shall be adopted, and the 24-hour error shall not be more than ± 5 seconds. In case of power failure of the device, the clock chip inside the device can still continue to work.

Fault simulation function: the device can simulate, single-phase ground alarm signal output, jump (close) relay signal output, communication soft message output, easy to conduct joint commissioning test.

Dual channel protection function: the zero sequence voltage sampling circuit of the device uses dual a/d or dual channel structure to avoid device misoperation caused by single a/d damage.