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TUDY ON THE IMPACT OF HARMONIC

DISTORTION IN CESC LT SYSTEM

MAINAK GHOSH, MOUSAM DUTTA, ARPAN KUMAR PRAMANICK

LT FAULT MANAGEMENT CENTRE, MAINS

Abstract

The concept of power quality, which had until a few years back, been too insigniﬁcant a topic to be considered

seriously from a utility perspective, will become as signiﬁcant an issue as the reliability of power supply in the

near future. The problems of neutral overloading, equipment overheating and system losses due to harmonic

proliferation will only increase from here on out due to increase in non-linear load drawn by electronic devices,

EV charging stations and distributed solar power generation. This paper gives an extensive overview of a series

of measurements done on CESC LT Distribution system to assess the signiﬁcance of harmonic impurity prevalent

in the network. It further explores the technical and economical aspects of the pollution injected into the power

system in a widely distributed manner by the 3.3 million LT consumers catered to by CESC and also brieﬂy

investigates about the possible remedial measures to the Harmonic problem.

Keywords: Power quality, Harmonics, system losses, remedial measures

INTRODUCTION ➣ A distorted current/voltage waveform

containing harmonics can be represented by

A harmonic is a signal or wave whose frequency is an a combination of the fundamental waveform

integral (whole-number) multiple of the frequency of and various other sinusoidal waveforms with

some reference signal or wave. diﬀerent frequencies. This is expressed by the

Fourier series stated below.

➤ Ideally, system voltage and current waveforms are

sinusoidal with presence of linear loads. Harmonics hf

are a distortion of the normal electrical current/

voltage waveform, generally transmitted by ¦y(t) Y0 Yh 2 sin(hwt Mh)

nonlinear loads, where the AC voltage is converted h1

to a DC voltage. The distortion travels back to the

power source and can aﬀect other equipment ➤ Where ω is the fundamental frequency (equal to 50

connected to the same source. Hz) in CESC system.

➤ Current harmonics are caused by the action of non- ➤ Odd harmonics have frequency which are odd

linear loads such as rectiﬁers, discharge lighting, or integer multiples of the fundamental frequency

saturated electric machines. Voltage harmonics are (h = 3,5,7,9,11,13,…) & even harmonics have

caused by the current harmonics ﬂowing through frequency which are even integer multiples of the

an impedance. Voltage distortion depends on fundamental frequency (h= 2,4,6,8,…)

System impedance and amount of distorted current.

➤ Harmonic number 0 is the constant or

DC component of the waveform. DC component

is the net diﬀerence between positive & negative

halves of complete waveform cycle.

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DISTORTION IN CESC LT SYSTEM

MAINAK GHOSH, MOUSAM DUTTA, ARPAN KUMAR PRAMANICK

LT FAULT MANAGEMENT CENTRE, MAINS

Abstract

The concept of power quality, which had until a few years back, been too insigniﬁcant a topic to be considered

seriously from a utility perspective, will become as signiﬁcant an issue as the reliability of power supply in the

near future. The problems of neutral overloading, equipment overheating and system losses due to harmonic

proliferation will only increase from here on out due to increase in non-linear load drawn by electronic devices,

EV charging stations and distributed solar power generation. This paper gives an extensive overview of a series

of measurements done on CESC LT Distribution system to assess the signiﬁcance of harmonic impurity prevalent

in the network. It further explores the technical and economical aspects of the pollution injected into the power

system in a widely distributed manner by the 3.3 million LT consumers catered to by CESC and also brieﬂy

investigates about the possible remedial measures to the Harmonic problem.

Keywords: Power quality, Harmonics, system losses, remedial measures

INTRODUCTION ➣ A distorted current/voltage waveform

containing harmonics can be represented by

A harmonic is a signal or wave whose frequency is an a combination of the fundamental waveform

integral (whole-number) multiple of the frequency of and various other sinusoidal waveforms with

some reference signal or wave. diﬀerent frequencies. This is expressed by the

Fourier series stated below.

➤ Ideally, system voltage and current waveforms are

sinusoidal with presence of linear loads. Harmonics hf

are a distortion of the normal electrical current/

voltage waveform, generally transmitted by ¦y(t) Y0 Yh 2 sin(hwt Mh)

nonlinear loads, where the AC voltage is converted h1

to a DC voltage. The distortion travels back to the

power source and can aﬀect other equipment ➤ Where ω is the fundamental frequency (equal to 50

connected to the same source. Hz) in CESC system.

➤ Current harmonics are caused by the action of non- ➤ Odd harmonics have frequency which are odd

linear loads such as rectiﬁers, discharge lighting, or integer multiples of the fundamental frequency

saturated electric machines. Voltage harmonics are (h = 3,5,7,9,11,13,…) & even harmonics have

caused by the current harmonics ﬂowing through frequency which are even integer multiples of the

an impedance. Voltage distortion depends on fundamental frequency (h= 2,4,6,8,…)

System impedance and amount of distorted current.

➤ Harmonic number 0 is the constant or

DC component of the waveform. DC component

is the net diﬀerence between positive & negative

halves of complete waveform cycle.

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