Gestión inteligente de Transformadores estratégicos

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Ing. Ricardo Rivero

Energy Sector Power Distribution

Gestión inteligente de

Transformadores

estratégicos

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Página 2 15-Jun-2011 Ing. Ricardo Rivero Energy Sector / ED SE

Agenda

A) General information

B) Regular and Advanced Diagnostic

C) Strategic transformer management program

D) Monitoring system on line

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Mortality Rate by Age

•Source: CIGRÉ

0

5

10

15

20

0

10

20

30

40

50

60 Age of Transformer

% Failures

GSU

Network

A) General Information

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A) General Information

Transformer failures:

Winding insulation Bushings Tap changers Other areas of concern:

Pollution, dust & debris affecting bushings & cooling systems

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A) General Information

Brittle insulation increases failures

Overloading increases heat = aged insulation

O₂ & moisture in oil break down insulation

Short circuits ‘overpower’ older designs

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A) General Information

Bushings

Inherent design (Type U) Tracking (Dust)

Tap Changers

Mechanical linkages

Cooling Systems

Blockage leads to heating & inefficiency

Transformer not rated to nameplate

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B) Regular and Advanced Diagnostics

Regular and Advanced Diagnostics

Routine Electrical Testing

FRA (Mechanical movement of the windings)

DFR (Dielectric properties of insulation system)

ADGA (Dissolved gas analysis using design characteristics)

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Routine Electrical Testing

Insulation Power Factor

Insulation resistance of windings and core Transformer Turns Ratio (TTR)

CT ratio & polarity Winding Resistance Winding Excitation Infrared Scanning

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Routine Oil Analysis

General Chemistry

Dissolved Gas Analysis (DGA), Concentrations of H₂, ethane, ethylene, methane, & acetylene

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FRA

Frequency Response Analysis (FRA) is a method of measuring the

transfer function of the windings of a transformer. Changes in the

transfer function reveal a wide range of failure modes, for example:

Axial Winding Collapse Hoop Buckling

Shorted Turns

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FRA: Axial Collapse

Axial winding collapse is likely to have the following characteristics:

Produced within a transformer winding due to excessive axial forces during a fault Failure likely to be catastrophic if transformer continues in service

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FRA: Hoop Buckling

Hoop buckling is produced within a transformer winding due to

excessive compressive forces during a fault.

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FRA: Shorted Turns

Shorted turns in transformers are produced by turn-to-turn faults and may have the following characteristics:

Adjacent turns lose paper and braze/weld together

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DFR

The Dielectric Frequency Response (DFR) test is a series of power

factor measurements at multiple frequencies. It provides more

information about the dielectric behavior of the insulation system. The

method be used to diagnose the following conditions in transformers:

Moisture in the cellulose insulation

High oil conductivity due to aging or overheating of the oil

Chemical contamination of cellulose insulation

Carbon tracking in cellulose

High resistance in the magnetic core steel circuit

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60 Distinguishing Between Aged Oil and Moisture

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Fitting the Right Dielectric Parameters

60

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Dielectric Response Fingerprint Function caused by a High

Core to Ground Resistance in Auxiliary Transformer

.01 .10 1 10 100 1000

Frequency, Hz XV to Ground

XV to Ground after Repair

High Core Ground Resistance

DFR

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Adv DGA

Close observation of dissolved gases in the oil and other oil properties

provides the most valuable information about transformer health. DGA

analysis tools takes the following into considerations:

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3D Simulation Solutions of Field Problems

verifications of hot-spot verification of electric field analysis and solution of

overheated bus-duct in large GSU’s

determining overload-ability.

Electrical field distribution over the winding / HV

bushing insulation structures

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A series of assessments to provide optimal asset decisions …

Phase I – Fleet Risk Screening

Phase II – Condition & Design Evaluation of Critical assets

Phase III – Life Profiling Phase IV – Implementation Prioritization of critical assets Improved capital forecasting Reduced O&M spending

Improved availability and reliability Improved operational efficiencies

Improved environmental, public safety profile

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130 units total

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Plot of Risk of Failure versus Importance

Urgent = 10

Priority = 40

Normal = 80

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Página 25 15-Jun-2011 Ing. Ricardo Rivero Energy Sector / ED SE 30-50% OF MAINTENANCE ACTIVITY IS UNNECESSARY (CIGRE-2000) OVERSPENDING

OS

UNDERSPENDING

US

$

$ $

OS=US - balanced budget

OS>US - lower maintenance $$$

TRANSFORMERS

RISK OF FAILURE PER TRANSFORMER MAINTENANCE $$$ PER TRANSFORMER

Budget Expenditures vs. Risk

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Transformador Cromatógrafo de Gases

Análisis de Disolución de Gases

GAS-Guard 8

Internet

Cuarto de Control Existente

Sistema de Monitoreo Y Gestión de Activos Siemens

SMGAS

Gestión de Mantenimiento y Alarma en caso de contingencia

Avisos / Alarmas / Informes Acciona

F.O. ETHERNET ETHERNET DNP i Switch Firewall VPN Firewall VPN

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Transformador

Internet

Cuarto de Control Existente

Sistema de Monitoreo Y Gestión de Activos Siemens

SMGAS

Software WEB UI, con alarma Y recomendación de acciones

Avisos / Alarmas / Informes Acciona

F.O. ETHERNET RS485 _DNP3 Switch Firewall VPN Firewall VPN F.O. ETHERNET ETHERNET

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Respaldo de Monitoreo y en caso extremo respaldo de Control y Operación Hacia Acciona vía VPN

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E) References

Repair and retrofitting through - Transformer Lifecycle Management Siemens AG 2010 Sitram - Monitoring - Transformer Lifecycle Management Siemens AG 2010

Energy automation Siemens 2011

Service Handbook for Power Transformers ABB 2006

IEEE C57.125 – IEEE Guide for Failure Investigation, Documentation, and Analysis fro Power Transformers and Shunt Reactor

C. Sweeter and T. McGrail, “Sweep Frequency Response Analysis – A Technical Paper from Doble Engineering”, Ver. 1.0 January 2003

McNutt, W.J. “CIGRE Survey on maximum Safe Operating Hot Spot Temperature”, From EPRI Proceedings on Transformer Overload and Bubble Evolution, EL-5807-SR, Junio 1988, pp. 5.2.1-5.2.4