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HITEC UNIVERSITY TAXILA
SIMULINK MODELLING OF SOLID
DIELECTRIC
PRESENTED BY: BASIT REHMAN HASHMI 21-MS-EE-004
PRESENTED TO: DR. KASHIF IMDAD
SUBJECT : DIELECTRIC MATERIAL AND ELECTRICAL INSULATIONS
SEMESTER: 2ND
CLASS: GRADUATE 1
RESEARCH PAPER
Modeling of Partial Discharge Mechanisms in Solid
Dielectric Material
by: Y. Z. Arief, W. A. Izzati, Z. Adzis
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ABSTRACT
• Partial discharge (PD) represents a physical phenomenon, in which discharges are involved in electrically weak
regions of solid insulation materials (mostly within gaseous or liquid inclusions).
• They cause damage to the insulation and often start from the enclosed voids and/or at interface defects. The
period in which the insulation is still in good operating condition is of great practical interest.
• This project was conducted by simulations based on an extended PD equivalent circuit in order to understand
the characteristics of PD in solid dielectric materials. In this project, PD mechanism in solid dielectric material
was modeled using Simulink in MATLAB .
• It is observed that the discharge current is proportional with the input voltage. The discharge current amplitude
for input 10 kV is half the input of 20 kV and a third of 30 kV input.
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INTRODUCTION
• Partial discharge (PD) is defined as localized electrical discharge within only a part of the insulation between two
separated conductors. In the real applications, PD is caused by the existence of voids in the insulation. Even if the local
electrical field in the void exceeds a threshold and a discharge occurs, it is limited within the void due to the strong
surrounding insulation, enough to avoid a complete breakdown. PD in voids is considered harmful, especially in high-
voltage systems from the engineering viewpoint as they cause energy loss and gradually degrade the insulation .
• PD may occur in solid, liquid and gaseous insulation media and are generally initiated by an excessive localized
electric field. The PD induced current in an external circuit depends on the nature of the discharge and the geometry of
the system
• PD phenomenon causes degradation in insulated materials. The investigation of insulated material behaviour under
electrical stress and the data obtained from PD measurements, provide the possibility to predict dielectric breakdown
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EQUIVALENT CRICUIT OF PARTIAL
DISCHARGE
• PD behaviour in inclusions (cavities, defects, etc.) in dielectrics can be represented by simple
equivalent circuit developed by Gemant & Philippoff in 1932, known as capacitance model. A
dielectric with an internal void is shown schematically .
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• U : applied voltage at power frequency
• C1 : capacitor representing the cavity
• C2 : capacitor representing insulating material around cavity
• C3 : capacitance of the remaining insulating material
• S : spark gap representing discharge of C1. C1 and C2 are generally not measurable.
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SIMULATION
• The PD circuit that has been used in this project came from a conventional circuit proposed by Gemant
& Philippoff in 1932. The circuit is also known as 3 Capacitance Model as shown in Fig. 1. The model
was then reconstructed in order to consider the additional electric field generated by preceding
discharges, as can be seen in Fig 2
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• Where: F : spark gap
• C1 : capacitance of defect (void, impulse)
• C2 : capacitance of the healthy series with the defect
• C3 : parallel capacitance in specimen
• C4 : capacitance of local charges accumulation.
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• The capacitor C4 is charged from the capacitor C1 during the PD process until the two voltages are
equal .
• The value of components in the circuit for the simulation is described in Table 1. This circuit was
implemented with Simulink application in MATLAB® software. The spark gap has been changed
with the breaker in simulation circuit as shown in Fig. below. This breaker is set with certain time
value to represent PD occurring time.
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THIS IS SIMULATED CIRCUIT ON MATLAB
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TABLE
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RESULTS AND DISCUSSION
• The simulation was run for 0.06 second. The applied voltage frequency was set to 50 Hz. The results of
the simulation are shown in Figs. 9 to 12 for each applied voltage (10, 15, 20, and 30 kV respectively)
which were observed from Scope. From the results, discharges vary at every input voltage. For an
increasing AC source, the amplitude of waveform in sampling resistance increased, as well as the
single discharges waveform in a void. We observed that the discharge current is proportional with the
input voltage
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INPUT VOLTAGE
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AT 10KV
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INPUT AT 20KV
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OUTPUT AT 20K
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INPUT AT 30KV
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OUTPUT AT 30KV
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IMPEDANCE MEASUREMENT
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CONCLUSION
• The simulation conducted showed that the extended PD equivalent circuit was able to represent the
behaviour of PD in solid dielectrics. This circuit is more accurate .
• There is a slight difference of voltage waveform and current discharges in the void from the original
model. This is due to the timing mode of the breaker. Breakers cannot simulate the perfect timing for
PD to occur. The breaker simulates the PD only once. The value of discharge current is dependent on
the input voltage. If the input voltage is increased then the discharge current will increase .
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REFERENCES
• [1] Kenroy Alexander Questelles, “Developing a Stochastic Model for Partial Discharge Detection In Voids of Polymeric Cable Insulation” University
Technology Malaysia: Master Thesis, 2006.
• [2] Boggs, S.A. “Partial discharge: overview and signal generation”, IEEE Electr. Insul. Mag., 1990, 6, (4), pp. 33–39.
• [3] A. L. Kupershtokh, C. P. Stamatelatos, and D. P. Agoris “Simulation of Partial Discharge Activity in Solid Dielectrics under AC Voltage” Vol. 32,
No. 8, pp. 680–683. © Pleiades Publishing, Inc., 2006.
• [4] M. G. Danikas, G. E. Vassiliadis, “Models of Partial Discharges (PD) in Enclosed Cavities in Solid Dielectrics: A Study of The Relationship of PD
Magnitudes to The Sensitivity of PD Detectors and Some Further Comments on Insulation Lifetime”, Journal of Electrical Engineering, vol. 54, No. 5-
6, pp. 132-135, 2003.
• [5] G. Chen, F. Baharudin, “Partial Discharge Modelling Based on a Cylindrical Model in Solid Dielectrics”, International Conference on Condition
Monitoring and Diagnosis, Beijing, China, pp. 1-5, Beijing, April 2008.
• [6] C.G. Karagiannopoulos, “A Model for Dielectrics Experiencing Partial Discharges under High Electric Fields”, Journal of Electrostatics 65, pp.
535–541, 2007.
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