HV Testing Lab research

CEEX Modul III

Development of on-site partial discharge measuring methods for power and instrument transformers

Contracting authority: National Centre for Programs Management
Contractor: National Research Development and Testing Institute for Electrical Engineering – ICMET Craiova

Programul : CEEX – Excellence research
Project category / project type: module III

Project acronym: PDM
Period of project development: 30.07.2006 – 30.06.2008

Partners involved in the project: no partners
Project leader: National Research Development and Testing Institute for Electrical Engineering – ICMET Craiova
Project Manager : ing. Popa Dorin
Telephone: +0351 402425

Main objective:
Partnership development of on-site partial discharge measuring methods for power and instrument transformers.

Time table for project achievement:

2006 – Stage 1: Study of the partial discharge measuring techniques, in strong disturbances conditions, used at worldwide level at present.
Deadline: 30.11.2006

2007 – Stage 2: Achievement of partial discharge measuring system
Deadline: 30.06.2007

2007 – Stage 3:Experiment of the new technique for partial discharge measurement .
Deadline: 30.11.2007

2008 – Stage 4: Result dissemination and preparation for project result utilization.
Deadline: 30.06.2008

Potential users:

Manufacturers of power transformers from Romania: Electroputere Craiova, ELEROM Roman, RETRASIB Sibiu.
Utilities from the national power grid: Transelectrica si Electrica SA.
Electric power generation companies: Termoelectrica, Hidroelectrica, Nuclear Power Plant Cernavoda.

Social and economic impact:
The project approaches a topic that aims at implementing a new measuring method which enables the electric power utilities to monitor continuously or discretely the operation of the power and instrument transformers preventing in this way their unexpected outages which generate financial damages, social discomfort and in the end, air and soil pollution.

Project presentation:
Project "Development of on-site partial discharge measuring methods for power and instrument transformers" was finalised by the achievement of a: measuring and location system for partial discharge sources.
The novelty of the achieved solution consists of coupling an electric circuit for synchronous measurement of partial discharges from all investigated transformer phases with an acoustic measurement system.
In order to discriminate the useful electric signals from the electromagnetic disturbances existing in the electric substations where the transformer works, it was developed a software which filters the signals generated by the Corona effect and the ones characterised by a high energy on a fixed frequency ( radio, TV waves etc).
The acoustic measurement is not influenced by the external disturbances but signal reception time is influenced by the different propagation media existing inside the transformer. In order to use the advantages of each of the two methods the results were optimised by a software having as stable parameter the partial discharge appearance time related to the zero passing of the high voltage. To be noticed the cooperation with the company OMICRON - Austria who delivered the multichannel system for synchronous electric measurement of partial discharges and with the Technical University – Berlin for partial discharges comparative measurements in the electric substation Urechesti, Gorj district.
The new system was validated by laboratory and on-site measurements on power and instrument transformers.
The intellectual property and commercialization rights for the transformer operational condition diagnosis service based on partial discharge measurement and location belong to ICMET Craiova.

Information dissemination:
Popa Dorin - Transformer Diagnosis Correlating DGA with PD Measurement Results. In the annals of Craiova University, series Electrical Engineering, No. 30/2006, ISSN: 1842-4805 pg. 103-107
Popa Dorin - Localization of partial discharges sources in power transformers. In International Symposium SIMC-EE 2007, Baile Olanesti 26-28 November 2007
Popa Dorin, Nicoara Tania - Power transformer diagnosis using the numeric technique for partial discharge measurement. In: Conference "Present performances of power transformers. Trends in the fields concerning design, manufacturing, mounting, maintenance and exploitation" Craiova, 07-08 October 2008.
Popa Dorin, Nicoara Tania- Evaluation of transformer insulation operational condition on the basis of partial discharge measurement. In : Round table " Progresses and trends in electric equipment development and testing " , Craiova 25 November 2008
Popa Dorin, Nicoara Tania, Marinescu Andrei, Manta Alexandru- PD Location by Acoustic Emission Method and Optical Transmission at Instrument Transformers in Reversed Mounting , In OptoTech 2009 Symposium. Application of Optoelectronic Measuring and Monitoring Methods in Romanian Power Grid. Cheia 6-8 May 2009.

Project utilization:
During 2008 the partial discharge measuring and localisation system was used to diagnose 22 power transformers for: Electroputere Craiova, RETRASIB Sibiu and Transelectrica.
Due to offering this service, the following economic results were obtained:
- direct incomes with a value of 189.200 lei
- expenses reduction at beneficiaries 240.000 euro
In the first trimester of 2009 diagnosis works, with a value of 60.200 lei, were performed on 7 power transformers for: ROMAG-PROD Turnu Severin, RETRASIB Sibiu, Electroputere Craiova and CNE Cernavoda. Diagnosis works with a value of 34.000 lei were performed on 7 instrument transformers for Electroputere. We appreciate a reduction of 70.000 euro of the expenses at beneficiary.