Existing Issues Associated With Electric Distribution System

Existing Issues Associated With Electric Distribution System

Sivaraman P. (TECH Engineering Service, Chennai, India) and Sharmeela C. (Department of Electrical and Electronics Engineering, College of Engineering, Anna University, Chennai, India)
DOI: 10.4018/978-1-7998-1230-2.ch002
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The common problems existing in electric distribution systems are: under voltage; overloading of distribution system components; unbalanced loading; transformer without OLTC operation; improper reactive power compensation; power theft; conversion of 3phase supply into 2phase supply; voltage sag; harmonics and system resonance condition; voltage fluctuations; problem in fault identification; transients; and renewable energy penetration, resulting in functional problems to both distribution power supply company as well as end user. This chapter discusses the various problems in the electric distribution system.
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The major components used in distribution systems are distribution transformers, distribution overhead lines, cables, switch gears like Air Circuit Breaker (ACB), Moulded Case Circuit Breaker (MCCB), Miniature Circuit Breakers (MCB), Residual Current Circuit Breaker (RCCB), fuses, etc., isolators, contactors, capacitor banks, harmonic filters, end user loads like motors, UPS systems, luminaries (incandescent lamps, florescent lamps, CFLs, LEDs, etc.), resistive loads (iron boxes, water heaters, etc.), electronic gadgets (laptops, mobile phones, digital watches, etc.) and diesel generators. Diesel generators in low voltage EDS are mostly standby generators and it will be in operation only if power grid supply is not available (Alhelou et al., 2019; Makdisie et al., 2018; Alhelou et al., 2018; Alhelou et al., 2016; Haes Alhelou et al., 2019; Njenda et al., 2018). These standby diesel generators are not operating parallel with the power grid at any point of time.

The distribution system is affected by various problems like voltage sag & swell, transients, under voltage & over voltage, unbalance, voltage fluctuations, harmonics, etc. Fault in transmission system have an impact in reduction of voltage in distribution system as voltage sag because transmission system prone to more numbers of transient faults (Sivaraman et al. 2017; Khan et al., 2019; Khan et al., 2018; Khan et al., 2017; Banteywalu et al., 2019; Anteneh et al., 2019; Molla et al., 2019, Molla et al., 2018, Jariso et al. 2018). The detailed explanation of problems in distribution systems are given in this chapter.


Problems In Electric Distribution System

The problems existing in EDS are

  • Under voltage

  • Overloading of distribution system components

  • Unbalanced loading

  • Transformer without OLTC operation

  • Improper reactive power compensation

  • Power theft

  • Conversion of 3 phase supply into 2 phase supply

  • Voltage sag

  • Harmonics and system resonance condition

  • Voltage fluctuations

  • Problem in fault identification

  • Transients

  • Renewable energy penetration

These problems are resulting in functional problems to both distribution power Supply Company as well as end user.

  • 1.

    Under Voltage: The under voltage is the one of the main problem of many low voltage public distribution systems. As per IEEE 1159-2009, under voltage is defined as reduction of voltage magnitude from 0.9pu to 0.1pu for the time duration greater than one minute. The causes of under voltage are sustained overloading of distribution circuit components, failure and inadequate reactive power compensation, switching on back to back higher capacity loads (IEEE Std, 2009, Chattopadhyay et al. 2011, Zobaa and Aleem, 2017). In India, there is no active voltage control in 66kV or 33kV below voltage level (GIZ, 2017).

Key Terms in this Chapter

Transient: It is a momentary variation in current, voltage, or frequency.

Unbalanced Loading: The imbalance occurs when an open or short circuit appears at the load.

Voltage Sag: A voltage sag or voltage dip is a short duration reduction in RMS voltage which can be caused by a short circuit, overload or starting of electric motors.

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