As a crucial component for ensuring the safe and stable operation of power grids, pilot protection not only requires the protection equipment itself to be reliable, but also demands that the transmission channel can transmit protection signals accurately and rapidly. When a system fault occurs, it is imperative to selectively and quickly remove the faulty line, preventing protection refusal to operate or maloperation. The full-line instantaneous pilot protection plays a vital role in the stable operation of high-voltage power grids.

Pilot protection mainly relies on channels to exchange measurement information of protection devices at both ends of the line, and distinguishes between internal faults and external faults through the variation of the exchanged information. The reliability of optical fiber differential protection devices largely depends on the reliability of the protection channel, and adopting a dual-channel mode is an effective means to improve channel reliability.

At present, the pilot protection with dual optical fiber channels for voltage classes of 220kV and above is often blocked due to channel faults, and it is difficult to quickly identify the root causes of the faults. The Relaystar-DFT20 Optical Fiber Differential Protection Dual-channel Comprehensive Tester, independently developed and produced by Wuhan Haomai, is a comprehensive tester integrating dual optical fiber channels, relay protection devices and intelligent terminals. It can track Beidou/GPS timing signals simultaneously, adopt Beidou/GPS dual-mode timing, and test the consistency of transmitting and receiving time delays of optical fiber pilot protection channels in relay protection systems.

△ Relaystar-DFT20 Optical Fiber Differential Protection Dual-channel Comprehensive Tester

This tester supports continuous recording and analysis of multiple time signal types (PPX, IRIG-B code, serial port message, NTP, PTP), and supports comparative testing of multi-channel time synchronization signals, monitors the time deviation of different time synchronization signals, and counts time deviation information. It can simulate abnormal time synchronization signals, facilitating the measurement of time response characteristics and stability of time-synchronized equipment. The device is equipped with hard contact inputs, outputs, and 100M/1000M optical ports. It supports importing the entire substation SCD file, can correctly configure the transmission and reception of corresponding GOOSE messages, conduct time response tests of intelligent terminals, and also supports SOE testing to continuously record the time accuracy of SOE.

△ Pilot Protection Channel Time Delay Test

Channel Time Delay Test: Supports testing the consistency of transmitting and receiving time delays of optical fiber pilot protection channels in relay protection systems.

Protection Function Test: Supports on-site protection commissioning and regular inspection tests of substations, and supports all general tests and special tests.

Network Message Analysis: Supports message receiving filtering, waveform, effective value, phase, angle and harmonic content analysis of SMV and FT3 messages, as well as parsing and analysis of GOOSE messages.

Merging Unit Test: Supports tests of merging unit discreteness, time delay, ratio error, angle error, etc.

Intelligent Terminal Test: Supports intelligent terminal response time test, including hard contact to GOOSE, GOOSE to hard contact conversion modes, etc.

One-click Automatic Test: Automatically matches the test template of the protection device with one click, and completes the full-function test of the protection device automatically.

Recently, during the maintenance of a 500kV substation of a provincial power company, the Relay Protection Star-DFT20 Optical Fiber Differential Protection Dual-channel Comprehensive Tester was used to test the pilot protection channel of Xudong Line 3. The measured transmission time delay was 348μs, which met the specification requirements and received unanimous praise from the user unit.