HJ International Latin America, Inc. New vision regarding the real average load of distribution transformers in Latinamerican electrical grids. The situation

HJ International Latin America, Inc.

New vision regarding the real average New vision regarding the real average load of distribution transformers in load of distribution transformers in

Latinamerican Latinamerican electrical grids.electrical grids.

The situation and the various paths to a The situation and the various paths to a soluction.soluction.

Arguments based on IEEE C57.91-1995 (R2004)Arguments based on IEEE C57.91-1995 (R2004)


DEFINITIONDEFINITION

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1 4 7

10

13

16

19

22

Load p.u.

rms equiv

Transf p.u.

Demand curve RMS value in kVADemand curve RMS value in kVA

Cm = ---------------------------------------------------- Cm = ----------------------------------------------------

Nominal kVA value of the Nominal kVA value of the transformer transformer


Regarding cycles of equivalent loadsRegarding cycles of equivalent loadsNote that the levels of overload and its duration are Note that the levels of overload and its duration are

extracted from the proper curves of the real load and extracted from the proper curves of the real load and not from a standard…!!not from a standard…!!

The accummulative concept of the loss of life…

…day, month, year, all its life…


Cycles of equivalent loadsCycles of equivalent loadsIEEE C57.91-1995IEEE C57.91-1995

A transformer subjected to any one of these 3 cycles will exhibit the same performance in terms of energy

While the RMS value of the load curve is below the nominal capacity of the transformer, the loss of life of the unit will be below the maximum

permitted!!


Diagram of temperaturesDiagram of temperatures

GRALTAGRUPO DE INVESTIGACION

EN ALTA TENSION


Diagram of temperaturesDiagram of temperatures

Direct measurement (thermocouples)

Indirect measurement (resistance)

Calculated(recomendations IEEE)

ΘSUP ΘTO

ΘINF

ΘA

Tanque Aceite Devanado

Temperatura [ºC]

Posición vertical

ΔΘW

ΔΘH

Nivel Superior Aceite

Nivel Superior Devanado

Nivel Inferior Devanado

ΔΘT

ΔΘT / 2

ΔΘAO

ΔΘTO

ΘAO

ΔΘW

ΘW

ΔΘBO

ΔΘT

Punto caliente

ΘH

GRALTAGRUPO DE INVESTIGACION

EN ALTA TENSION


Regarding the limits of load and Regarding the limits of load and temperaturetemperature

For operations above the nominal loadFor operations above the nominal loadPer IEEE C57.91 – Table 6Per IEEE C57.91 – Table 6

DISTRIBUTION TRANSFORMERSDISTRIBUTION TRANSFORMERS

Temperature of the hot spot of the conductor: 200degC

Short duration load (1/2 hour or less) 300%

Top oil temperature: 120degC


Regarding the limits of load and Regarding the limits of load and temperaturetemperature

For operation s above the nominal load For operation s above the nominal load Per IEEE C57.91 – Table 7Per IEEE C57.91 – Table 7POWER TRANSFORMERSPOWER TRANSFORMERS

Temperature of the hot spot of the conductor: 180degC

Short duration load (1/2 hour or less): 200%

Top oil temperature: 110degC


How a COMPLETE heat run should be done…How a COMPLETE heat run should be done…


DEFINITION:DEFINITION:Factor regarding energerized Factor regarding energerized

medium load medium load

• Annual invoicing in GWhAnnual invoicing in GWh

Fcme = --------------------------------------------------Fcme = --------------------------------------------------

CITD * fp * 24 * 360CITD * fp * 24 * 360

CITD: Installed capacity of Distribution Transformers, CITD: Installed capacity of Distribution Transformers, GVAGVA

fp: Global power factor of the systemfp: Global power factor of the system


Average loadability of Average loadability of distribution transformers en distribution transformers en

the system (Example)the system (Example)

0-10%>25%10-25%

• The average sizes in the grid can be reduced in factors of 2 to 5!!


For the losses and typically kVA cost that we found For the losses and typically kVA cost that we found throughout the Latinamerican grids, the minimum operative throughout the Latinamerican grids, the minimum operative

cost for Cm to be between 50% and 75% of the nominal cost for Cm to be between 50% and 75% of the nominal capacity of the distribution transformers. capacity of the distribution transformers.

OPTIMUM SIZING

0

20,000

40,000

60,000

80,000

100,000

120,000

15% 25% 60% 80% 110%

La

USD

Costo total

Costo energia

Costo activos


THE COMPROMISE…THE COMPROMISE…

WHERE WE ARE AT WHERE WE ARE AT TODAY:TODAY:

WHERE WE HAVE TO BE: WHERE WE HAVE TO BE:

Cm = 15 Cm = 15 %%

Cm = 60 to 75 Cm = 60 to 75 %%


Determination of the real demand Determination of the real demand

Indirect measurements – CEMIG (Gemini)

Administration of actives due to accummulated loss of life

Compare the energy sold to the end users connected to the transformer to the energy the transformer has the capacity to

deliver

The real losses at the sight of installation are not accounted for.


Direct measurement of energy Direct measurement of energy delivered by the transformerdelivered by the transformer

• The reading is compared to the energy sold to the end-users The reading is compared to the energy sold to the end-users connected to the unit. connected to the unit.

• If you compare the energy delivered by the transformer to a load If you compare the energy delivered by the transformer to a load profile, you will have a precise vision of the percentage of load. profile, you will have a precise vision of the percentage of load.

(Fuente: Redes de EEPPM)(Fuente: Redes de EEPPM)


Other variants practiced currentlyOther variants practiced currently

• Digital measurementsDigital measurements

• Remote readingsRemote readings

• Remote signalsRemote signals

(Fuente: Redes de EEPPM)(Fuente: Redes de EEPPM)


Distribution of loads in a grid with Distribution of loads in a grid with optimum sizingoptimum sizing

• CRITICAL ZONE WITH CRITICAL ZONE WITH THE NEED TO THE NEED TO ADEQUATE THERMO ADEQUATE THERMO PROTECTIONPROTECTION

• Example: Cm/Fd (0.60/0.65 Example: Cm/Fd (0.60/0.65 =0.92)=0.92)

CRITICALLOAD ZONE

AVERAGE LOAD 50 – 75 %


IS EVERYTHING CLEAR ?IS EVERYTHING CLEAR ?


Factors to consider for the optimum sizing Factors to consider for the optimum sizing based on the consumption of energybased on the consumption of energy

• REAL LOAD CURVE OR CHARACTERIZED AND 2 EQUIVALENT CYCLES.REAL LOAD CURVE OR CHARACTERIZED AND 2 EQUIVALENT CYCLES.

• DETERMINE THE RMS VALUE OF THE LOAD CURVE BASED ON THE DETERMINE THE RMS VALUE OF THE LOAD CURVE BASED ON THE ACTUAL CONSUMPTION.ACTUAL CONSUMPTION.

• LIMIT THE PROJECTION OF THE LOAD CURVE TO NO MORE THAN 5 LIMIT THE PROJECTION OF THE LOAD CURVE TO NO MORE THAN 5 YEARS. YEARS.

• DEFINED A UNTI SIZE THAT WILL REACH ITS OPTIMUM LOAD IN THE DEFINED A UNTI SIZE THAT WILL REACH ITS OPTIMUM LOAD IN THE PROJECTED TIME.PROJECTED TIME.

• SELECT AN APPROPRIATE THERMAL PROTECTIONSELECT AN APPROPRIATE THERMAL PROTECTION


The type of transformer to be used The type of transformer to be used in an optimized load environmentin an optimized load environment

To successfully operate distribution To successfully operate distribution transformers at Cm levels between 50% transformers at Cm levels between 50%

and 75%, it is considered imperative and 75%, it is considered imperative that the protective devices used for the that the protective devices used for the

transformer, identify those levels of transformer, identify those levels of overload in magnitud and duration that overload in magnitud and duration that cause loss of life above the maximum cause loss of life above the maximum

permitted. permitted.


The areas of Over-Current Protection in a The areas of Over-Current Protection in a transformer...transformer...


The type of transformer to be utilized on The type of transformer to be utilized on optimum load environments and optimum load environments and

THE DEFINITIONS OF THE PROTECTION TO BE THE DEFINITIONS OF THE PROTECTION TO BE UTILIZEDUTILIZED

• Emphasis on the control of the thermal compartment (following the load currents and the interior temperatures)

• Asset management of the gridAsset management of the grid

• Reduction of installation costs.Reduction of installation costs.

• Significant reductions of the global failure Significant reductions of the global failure indices of transformers in the distribution system.indices of transformers in the distribution system.


The type of transformer to be utilized in an The type of transformer to be utilized in an optimum load environment…optimum load environment…

Lighted signal

or

Information sent remotely

Priviledging the need to interrupt dangerous load y even finding a better solution, we are installing CSP type

transformers to provide an exact thermal protection and the capacity to interrupt at the site.


The solution that the CSP transformer offers…The solution that the CSP transformer offers…

SELF-SELF-PROTECTEDPROTECTED

CONVENTIONALCONVENTIONAL

CAJA NEGRA



HV ARRESTER

LV BREAKER

FUSES

LV ARRESTER



SIGNAL LIGHT

HANDLE AND EMERGENCY OVERLOAD LEVER


The signal lamp as an element in providing an The signal lamp as an element in providing an effective managemente of loads and assets effective managemente of loads and assets along with an important role in balancing along with an important role in balancing

loads.loads.

• LIGHT OFFLIGHT OFF

• STATUS OF GRID AND STATUS OF GRID AND LOAD ARE NORMALLOAD ARE NORMAL

• LIGHT ONLIGHT ON

• STATUS OF GRID AND STATUS OF GRID AND LOAD ARE ABNORMALLOAD ARE ABNORMAL


A practical application of the proposed A practical application of the proposed model model

Case CFE – Veracruz District/Division

Pilot grid used to size unit with an optimum Cm


Summary of the pilot project achieved Summary of the pilot project achieved in the City of Veracruz - Mexicoin the City of Veracruz - Mexico

1. GRID INSTALLED OPTIMIZED2. Number of units 39 393. Average kVA 43.1 16.84. Total KVA 1,722.5 6555. Kwh./year 1,012,283 1,012,2836. Fcme 15.2% 39%7. Capitalized cost US$65.8kUS$34.4k units + losses8. % Capitalized cost. 100% 52.2%9. Type of units Conventional CSP


Summary of the pilot project Summary of the pilot project achieved in the City of Veracruz - achieved in the City of Veracruz -

MexicoMexico


Important points for a successful Important points for a successful applicationapplication

COORDINATION OF PROTECTIVE DEVICES AND REAL COORDINATION OF PROTECTIVE DEVICES AND REAL EXERCISES OF OVERLOAD PROTECTIONEXERCISES OF OVERLOAD PROTECTION

kk TTTR

RT 0

0


When making an economic evaluation of a When making an economic evaluation of a project using conventional vs CSP type project using conventional vs CSP type

transformerstransformers

THE SIZE OF TRANSFORMER BEING COMPARED THE SIZE OF TRANSFORMER BEING COMPARED ARE DIFFERENTARE DIFFERENT

CONVENTIONALCONVENTIONAL

kVA = X kVA = X/2kVA = X/2


The experience in Mexico was worth The experience in Mexico was worth the effort… the effort…

Letter from the Sub-Director of CFE indicating all the benefits achieved.


ENDEND

NATALIA

Other recommendations:

The case of transformers in Distribution Substations

Primary and secondary distribution cables

Orlando Giraldo – Sales and Operations Manager - HJ International Latin Orlando Giraldo – Sales and Operations Manager - HJ International Latin [email protected] – USA (636) 677 3421 – (Colombia) 57 1 – USA (636) 677 3421 – (Colombia) 57 1 478 4141478 4141

Documents

HJ International Latin America, Inc. New vision regarding the real average load of distribution transformers in Latinamerican electrical grids. The situation