Project Overview
Three 500 kV substations operated by the ultra-high-voltage maintenance company of State Grid Hebei Electric Power are equipped with GIS partial discharge (PD) online monitoring systems supplied by Zhuhai Huawang Technology Co., Ltd. All three projects passed acceptance in 2022, and customer-stamped acceptance reports are on file.
In line with the company’s policy for public materials, substation names are omitted in this summary. The stamped acceptance documents can be presented to qualified customers and design institutes on request.
Why 500 kV GIS Monitoring Matters
GIS equipment is fully enclosed, so internal insulation defects are difficult to detect by visual inspection or routine shutdown tests. At 500 kV, a single GIS failure can affect a wide area of the transmission network, which makes early detection of partial discharge activity particularly valuable.
Online monitoring keeps sensors installed on the GIS enclosures during normal operation. Instead of collecting PD data only during scheduled outages, the system records signals continuously and accumulates a trend that maintenance personnel can review over time.
Detection Methods and Quantitative Basis
The monitoring system combines multiple PD detection methods so that electromagnetic and acoustic observations can be checked against each other:
- UHF (ultra-high frequency) sensing of electromagnetic signals emitted by discharge activity inside the GIS chambers.
- AE (contact ultrasonic) sensing of acoustic emissions transmitted through the enclosure.
- TEV (transient earth voltage) sensing as a supplementary method at suitable positions.
For quantitative assessment, Huawang’s PD measurement chain is based on the pulse current method defined in IEC 60270, which is the only method that yields a traceable apparent-charge value in picocoulombs (pC). Laboratory calibration results and online monitoring readings are always reported as separate values and are not mixed.
Acceptance and Operation Records
The three projects were accepted in 2022. Together with other projects, they form part of the more than 40 customer-stamped operation reports, acceptance reports and thank-you letters held by the company, covering 500 kV, 220 kV and 110 kV substations as well as distribution, generation and industrial applications.
Project Details
- Voltage level: 500 kV
- Equipment type: Gas-insulated switchgear (GIS)
- Scope: Partial discharge online monitoring at three substations
- Customer type: State Grid ultra-high-voltage operation company (Hebei, China)
- Acceptance: 2022, customer-stamped acceptance reports
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