issouribehere – argentina – rif session 2 – 0513

Frankfurt (Germany), 6-9 June 2011

ISSOURIBEHERE – Argentina – RIF Session 2 – 0513

PERTURBATION MEASUREMENTS ON OVERHEAD NETWORKS USING ELECTRIC FIELD SENSORS

Advantages

Access from public areas

Practical, low costs and time saving

Applications

Detection of disturbing loads

Statistical Control of Supply Quality

Objective Measuring voltage disturbances

referred to industrial frequency value,

such as flicker, harmonics, sags


ISSOURIBEHERE – Argentina – RIF Session 2 – 0513 2


Measuring an electric field between two electrodes.

It is similar to a capacitive voltage divider where the HV capacitor has been replaced by a parasitic one.

Principle used in HV Labs

C

V E G

u tu t

G k k

Where:u(t) = Potential to be determined [V].um(t) = Potential measured with the EFS [V].

GV = Voltage gain between the output of the electric

field sensor and the measurement equipment [V/V].kE = EFS transduction constant =

[m].kG = Geometric constant of physical installation [1/m].

0 BA C

For measuring perturbations - referred to the fundamental frequency voltage – It is only necessary to reproduce the waveshape. Due to this it is not necessary to know the constants GV, kE, kG, being enough to verify the linearity and the independence of the frequency.

1

hh

UD

U

1

UPst

U



PERTURBATION MEASUREMENTS ON OVERHEAD NETWORKS USING ELECTRIC FIELD SENSORSb ac

One channel EFS measurement reproduces + and – sequence but not 0

1 1 2 1 3 1m R Rh S Sh T ThU k U U k U U k U U

120º 120º

1 2 3

120º 120º1 1 1 2 3

jh jhh h

j jmeasured real

U U k k e k e

U U k k e k e

h seq V3Φ Vm

2 - 1 1

3 0 2 2.5

4 + 1 1

5 - 10 10

6 0 1 1.2

Solving equations, the mathematic result is:

Testing the circuit, the result is:




HV Lab experiences and contrastFlicker and harmonics were applied to a HV installation using a LV/HV transformer excited with an electronic power generator. IEC meters were used

Frequency Response. The transducer is installed inside a parallel plate capacitor. LV tracking generator

Measurement system EFS + recording equipment meet error 5 %, IEC 61000-4-15 Flicker standard and Class I IEC 61000-4-7 Harmonics standard.




Field measurements Flicker comparison: HV with EFS vs LV conventional Bragado City Flicker measurement (220 V)

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

5,5

6,0

17:30 20:50 00:10 03:30 06:50 10:10 13:30 16:50 20:10 23:30 02:50 06:10

Time

Pst

PstPst95%

Flicker in Bragado

LV conventional

measurements

Flicker

HV with EFS vs LV conventional

Subtransmission area explored

∆V/V




Field measurements Localizing flicker Sources




1.Flicker measurements in overhead lines with the EFS are feasible to perform in compliance with required uncertainties, according to International Standards.

2. The following steps shall be carried out to find the geographic location of the prevailing Flicker source:

Perform measurements with an EFS in different nodes of the power system – keeping one conventional Flicker measurement in a reference place –.

Obtain the topology and the electrical data of the power system to be inspected, and determine (by manual calculations or by computer simulations) the effects of a predominant Flicker source in different nodes of the power system.

Correlate both results and determine the geographic location of the predominant Flicker source.

Localizing flicker Sources Summary




Harmonic measurements Results obtained with the same EFS, during flicker measurements

Saladillo node was over the 5th harmonic limit

Chacabuco node should be checked longer

The other nodes are within the limits

The results for the 3rd harmonic and its multiples should be considered only as indicative 0.0

0.5

1.0

1.5

2.0

2.5

3.0

H3 H5 H7 H9 H11 H13 H15Harmonic order

Uh

/U1

[%

]

Bragado

Chivilcoy

Chacabuco

Saladillo




It is a practical way to measure harmonics, flicker and other perturbations related to industrial frequency voltage, in compliance with IEC rules under 1Φ/3Φ grids (+,- seq, not 0)

It can be used as a powerful tool for finding disturbing loads along aerial transmission / distribution grids by accessing from public areas

It is a useful tool for statistical inspection of PQ in widespread electrical systems

The EFS based measurement method is particularly useful where both cost and physical location drawbacks cannot be addressed

Remarks




[1] M.Del Pozo, D.Esteban, P.Issouribehere, G.Barbera (IITREE FI-UNLP) A. Funes, A. Ledezma (YACYLEC), 2010, "Field measurements and modelling of high frequency transients during disconnect switch operations in EHV Substations. Assessment of their effects on Current Transformers", International Congress of CIGRE (Conseil International des Grands Réseaux Electriques). Paper: A3_207_2010. Paris, France, Ag. 2010.

[2] G. Casas, P. Issouribehere “Aplicación de un medidor de campo eléctrico como transductor para mediciones de perturbaciones en redes”. II ERLAC CIGRE CE 36. Puerto Iguazú, Argentina, junio 1987.

[3] ENRE (Argentina) Resoluciones 184/00: “Base Metodológica para el Control de la Calidad del Producto Técnico. Etapa 2” y ENRE 99/97: “Base Metodológica para el Control de la Emisión de Perturbaciones. Producto Técnico - Etapa 2”

[……….] IEC EMC Standards

References




Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos IITREE-LAT)FACULTAD DE INGENIERÍA - UNIVERSIDAD NACIONAL DE LA PLATA - ARGENTINA

www.iitree-unlp.org.ar

Daniel Esteban, Fernando Issouribehere, Pedro Issouribehere

issouribehere – argentina – rif session 2 – 0513

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