Online Monitoring System For High-Frequency Partial Discharge in Cables

The MOEORW-W5086LF Cable High-Frequency Partial Discharge Online Monitoring System is independently developed and manufactured in strict accordance with two authoritative power industry standards: Q/GDW 11304.5-2015 Technical Specifications for Live Detection Instruments of Power Equipment Part 5: Technical Specifications for High-Frequency Partial Discharge Live Detection Instruments and DL/T 2271-2021 Technical Specifications for Cable High-Frequency Partial Discharge Online Monitoring Systems. It is specially developed for long-term online insulation condition monitoring of high-voltage cable lines.

Industry operation statistics show that over 90% of high-voltage cable failures are caused by partial discharge resulting from insulation defects on cable terminals and intermediate joints. This system installs high-frequency current sensors on cable grounding downleads to couple partial discharge pulse currents, realizes 24/7 uninterrupted monitoring of joint insulation aging, water tree defects and discharge faults, and gives early warnings against insulation breakdown and line short-circuit accidents.

Three transmission architectures are available for the system: wired optical fiber, wireless LoRa and 4G cloud platform, which support mass deployment in all scenarios including urban power grids, industrial & mining power distribution, rail transit cables and underground pipe galleries. A single system can support a maximum of 200 distributed acquisition units without pressure for expansion of large-scale projects.

The system adopts the mature and widely recognized High-Frequency Current Transformer (HFCT) detection principle in the power industry. When partial discharge occurs at cable joints, discharge pulse currents will propagate along the grounding wire of the cable metal sheath. Split open-type high-frequency CT sensors couple 0.3MHz~30MHz high-frequency discharge signals. The signals are filtered, converted via 14-bit AD modules and noise-reduced through FPGA parallel processing in the acquisition unit to filter out on-site interference such as sheath circulating currents and power frequency clutter.

The equipment is equipped with optical fiber time base synchronization technology, which achieves a synchronization time difference of less than 100ns among multiple acquisition units and realizes synchronous sampling of three-phase channels. Accurate positioning of faulty joints is completed based on the time difference of discharge signals. The algorithm can distinguish three types of grounding currents (capacitance current from single-end grounding, DC current induced by water trees and partial discharge pulse current), and separate interference signals through combined time-domain and frequency-domain analysis algorithms to eliminate false alarms caused by on-site electromagnetic noise.

Standard Configuration: Split Open-Type High-Frequency Current Sensor
Featuring a split open magnetic core structure, the sensor can be quickly installed without cutting off cable grounding downleads or power interruption. The whole unit is equipped with a full-metal electromagnetic shielding box to suppress clutter interference from on-site inverters and high-voltage lines. The magnetic core is made of high-permeability material for high frequencies, with a detection frequency band of 0.3~30MHz and a minimum detectable discharge signal of 5PC, meeting the industry high-sensitivity standard. Integrated waterproof and dustproof packaging enables long-term stable operation in outdoor cable ducts.

Optional Configuration: Low-Frequency Sheath Circulating Current Sensor
It can synchronously monitor 0~200A grounding circulating current of cable metal sheaths and identify faults such as sheath insulation damage, multi-point grounding and stolen grounding wires. One system realizes dual monitoring of insulation partial discharge and metal sheath health, enabling engineering contractors to supply complete packaged sets and improve quotation competitiveness for projects.

Core Host: 3-Channel Online Monitoring Acquisition Unit
It supports standard 3-channel synchronous sampling for Phase A/B/C, with an ultra-high sampling rate of 100MS/s and 14-bit high-precision AD conversion. Built-in FPGA realizes local edge computing, and signal noise reduction & feature value extraction are all completed on the terminal to reduce computing pressure on the background server. The aluminum alloy waterproof chassis operates stably under a wide temperature range of -25℃~50℃ with a total power consumption of only 16W, suitable for tunnels and outdoor environments without air conditioning. Standardized interfaces support pluggable replacement of optical fiber / LoRa / 4G communication modules for flexible selection according to bulk project demands.

Network Core: Data Concentrator
It supports data aggregation via multiple links including optical fiber, network cable, 4G and LoRa, with a maximum transmission distance of 20km between equipment nodes. A visualized configuration tool is matched, and network setup can be completed only by filling in IP addresses and server access URLs without professional programmers for on-site debugging. A single concentrator uniformly summarizes monitoring data from hundreds of acquisition units, suitable for centralized management projects of large cable tunnels and multi-station power grids, which significantly shortens construction and debugging man-hours.

Advantage 1: Ultra-Large Distributed Networking, Perfectly Adapted to Large-Scale Bulk Engineering Projects
A single system can connect 200 monitoring units for online operation simultaneously with TCP/IP optical fiber daisy-chain networking. The system automatically identifies and configures newly added or removed terminals without secondary manual settings. Independent optical subnets are isolated from each other, and multi-tunnel & multi-area stations can be uniformly managed on one single platform.

Advantage 2: Edge Computing & Powerful Anti-Interference Performance, Greatly Reducing After-Sales Maintenance Complaints
The acquisition unit is equipped with an FPGA local parallel computing chip, and dual time-domain & frequency-domain filtering algorithms accurately distinguish interference signals from real partial discharge. The whole equipment can withstand 600kV flashover impact without damage or loss of monitoring data under line fault surges. It can capture weak discharge signals as low as 5PC, meeting both requirements of zero missed alarms and zero false alarms.

Advantage 3: Full Coverage of Three Communication Architectures, Adaptable to All On-Site Working Conditions for Bidding & Higher Bid Winning Rate
Optical Fiber Mode: For long-distance underground tunnels and comprehensive pipe galleries, stable transmission up to 20km without signal attenuation;
LoRa Wireless Mode: For old cable duct renovation and sites without pipeline laying, eliminating construction costs of optical fiber wiring;
4G Cloud Platform Mode: For isolated field cables and cross-regional multi-station projects, supporting remote viewing of monitoring data anytime and anywhere via external network.

Advantage 4: WEB Cloud Software Without Client Installation, Lowering Operation Threshold for Clients' Maintenance Staff & Smoother Acceptance
Adopting B/S architecture web platform, users can log in and access via browsers on computers and mobile phones without separate downloading and installation of client programs. A large-capacity SQL Server database is built in to store full monitoring data for 10 years completely. It automatically generates partial discharge trend reports and graded early warning records, supports one-click export and printing, fully matching the filing specifications of power grid maintenance ledgers.

Advantage 5: Multi-Dimensional Standard Partial Discharge Spectrograms with Intuitive Fault Diagnosis, Extra Scoring Item for Technical Bidding Documents
Four types of standard spectrograms commonly used in the power industry are built in the system:
Long-Term Trend Line Chart: Track the long-term change trend of discharge capacity to predict the slow aging process of insulation;
PRPD 2D Phase Spectrogram: Distinguish different defect types such as internal discharge, surface discharge and floating discharge;
Phase Line Spectrogram: Intuitively display the distribution range of discharge signals on power frequency phases;
PRPS 3D Spectrogram: Statistical analysis of multi-cycle discharge to accurately judge the severity level of faults.

Advantage 6: Multi-Function Expandable Design for All-in-One Monitoring, Optional Sensors to Improve Cost Performance of Complete Set Procurement
The standard function is high-frequency partial discharge monitoring, with optional sheath circulating current and sheath voltage sensors available on demand. One set of equipment synchronously monitors three core hidden dangers of cables including partial discharge insulation defects, sheath damage and grounding loop faults, replacing multiple single-function monitoring equipment and lowering clients' comprehensive procurement cost for complete sets.

1)Real-Time Monitoring Dashboard: The home page summarizes the total number of stations, online/offline equipment quantity and statistics of daily/monthly abnormal early warnings. Fault sensor points are highlighted in red and yellow for maintenance staff to quickly locate fault areas.
2)Visualized Equipment Configuration Function: Custom aliases can be set for stations, acquisition units and sensors, and batch import of equipment ledgers is supported for unified ledger management of large multi-station projects.
3)Multi-Condition Data Query & Report Export: All historical sampling data can be filtered by time period, equipment serial number and early warning status. Standardized maintenance reports are automatically generated with one-click export and printing to meet the data requirements of power grid project acceptance.
4)Graded Early Warning Push Mechanism: Users can customize partial discharge thresholds to distinguish two levels of warnings (attention warning & alarm warning). Early warning messages are pushed synchronously on the cloud platform for maintenance staff to dispose of insulation hidden dangers remotely in advance.